#
# Copyright (c) 2001 Bizar Software Pty Ltd (http://www.bizarsoftware.com.au/)
# This module is free software, and you may redistribute it and/or modify
# under the same terms as Python, so long as this copyright message and
# disclaimer are retained in their original form.
#
# IN NO EVENT SHALL BIZAR SOFTWARE PTY LTD BE LIABLE TO ANY PARTY FOR
# DIRECT, INDIRECT, SPECIAL, INCIDENTAL, OR CONSEQUENTIAL DAMAGES ARISING
# OUT OF THE USE OF THIS CODE, EVEN IF THE AUTHOR HAS BEEN ADVISED OF THE
# POSSIBILITY OF SUCH DAMAGE.
#
# BIZAR SOFTWARE PTY LTD SPECIFICALLY DISCLAIMS ANY WARRANTIES, INCLUDING,
# BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS
# FOR A PARTICULAR PURPOSE.  THE CODE PROVIDED HEREUNDER IS ON AN "AS IS"
# BASIS, AND THERE IS NO OBLIGATION WHATSOEVER TO PROVIDE MAINTENANCE,
# SUPPORT, UPDATES, ENHANCEMENTS, OR MODIFICATIONS.
#

"""Hyperdatabase implementation, especially field types.
"""
__docformat__ = 'restructuredtext'

# standard python modules
import os, re, shutil, weakref

# roundup modules
import date, password
from support import ensureParentsExist, PrioList, sorted, reversed
from roundup.i18n import _

#
# Types
#
class _Type(object):
    """A roundup property type."""
    def __init__(self, required=False, default_value = None):
        self.required = required
        self.__default_value = default_value
    def __repr__(self):
        ' more useful for dumps '
        return '<%s.%s>'%(self.__class__.__module__, self.__class__.__name__)
    def get_default_value(self):
        """The default value when creating a new instance of this property.""" 
        return self.__default_value
    def sort_repr (self, cls, val, name):
        """Representation used for sorting. This should be a python
        built-in type, otherwise sorting will take ages. Note that
        individual backends may chose to use something different for
        sorting as long as the outcome is the same.
        """
        return val

class String(_Type):
    """An object designating a String property."""
    def __init__(self, indexme='no', required=False, default_value = ""):
        super(String, self).__init__(required, default_value)
        self.indexme = indexme == 'yes'
    def from_raw(self, value, propname='', **kw):
        """fix the CRLF/CR -> LF stuff"""
        if propname == 'content':
            # Why oh why wasn't the FileClass content property a File
            # type from the beginning?
            return value
        return fixNewlines(value)
    def sort_repr (self, cls, val, name):
        if not val:
            return val
        if name == 'id':
            return int(val)
        return val.lower()

class Password(_Type):
    """An object designating a Password property."""
    def from_raw(self, value, **kw):
        if not value:
            return None
        try:
            return password.Password(encrypted=value, strict=True)
        except password.PasswordValueError, message:
            raise HyperdbValueError, \
                    _('property %s: %s')%(kw['propname'], message)

    def sort_repr (self, cls, val, name):
        if not val:
            return val
        return str(val)

class Date(_Type):
    """An object designating a Date property."""
    def __init__(self, offset=None, required=False, default_value = None):
        super(Date, self).__init__(required = required,
                                   default_value = default_value)
        self._offset = offset
    def offset(self, db):
        if self._offset is not None:
            return self._offset
        return db.getUserTimezone()
    def from_raw(self, value, db, **kw):
        try:
            value = date.Date(value, self.offset(db))
        except ValueError, message:
            raise HyperdbValueError, _('property %s: %r is an invalid '\
                'date (%s)')%(kw['propname'], value, message)
        return value
    def range_from_raw(self, value, db):
        """return Range value from given raw value with offset correction"""
        return date.Range(value, date.Date, offset=self.offset(db))
    def sort_repr (self, cls, val, name):
        if not val:
            return val
        return str(val)

class Interval(_Type):
    """An object designating an Interval property."""
    def from_raw(self, value, **kw):
        try:
            value = date.Interval(value)
        except ValueError, message:
            raise HyperdbValueError, _('property %s: %r is an invalid '\
                'date interval (%s)')%(kw['propname'], value, message)
        return value
    def sort_repr (self, cls, val, name):
        if not val:
            return val
        return val.as_seconds()

class _Pointer(_Type):
    """An object designating a Pointer property that links or multilinks
    to a node in a specified class."""
    def __init__(self, classname, do_journal='yes', required=False,
                 default_value = None):
        """ Default is to journal link and unlink events
        """
        super(_Pointer, self).__init__(required, default_value)
        self.classname = classname
        self.do_journal = do_journal == 'yes'
    def __repr__(self):
        """more useful for dumps. But beware: This is also used in schema
        storage in SQL backends!
        """
        return '<%s.%s to "%s">'%(self.__class__.__module__,
            self.__class__.__name__, self.classname)

class Link(_Pointer):
    """An object designating a Link property that links to a
       node in a specified class."""
    def from_raw(self, value, db, propname, **kw):
        if value == '-1' or not value:
            value = None
        else:
            value = convertLinkValue(db, propname, self, value)
        return value
    def sort_repr (self, cls, val, name):
        if not val:
            return val
        op = cls.labelprop()
        if op == 'id':
            return int(cls.get(val, op))
        return cls.get(val, op)

class Multilink(_Pointer):
    """An object designating a Multilink property that links
       to nodes in a specified class.

       "classname" indicates the class to link to

       "do_journal" indicates whether the linked-to nodes should have
                    'link' and 'unlink' events placed in their journal
    """

    def __init__(self, classname, do_journal = 'yes', required = False):

        super(Multilink, self).__init__(classname,
                                        do_journal,
                                        required = required,
                                        default_value = [])        

    def from_raw(self, value, db, klass, propname, itemid, **kw):
        if not value:
            return []

        # get the current item value if it's not a new item
        if itemid and not itemid.startswith('-'):
            curvalue = klass.get(itemid, propname)
        else:
            curvalue = []

        # if the value is a comma-separated string then split it now
        if isinstance(value, type('')):
            value = value.split(',')

        # handle each add/remove in turn
        # keep an extra list for all items that are
        # definitely in the new list (in case of e.g.
        # <propname>=A,+B, which should replace the old
        # list with A,B)
        do_set = 1
        newvalue = []
        for item in value:
            item = item.strip()

            # skip blanks
            if not item: continue

            # handle +/-
            remove = 0
            if item.startswith('-'):
                remove = 1
                item = item[1:]
                do_set = 0
            elif item.startswith('+'):
                item = item[1:]
                do_set = 0

            # look up the value
            itemid = convertLinkValue(db, propname, self, item)

            # perform the add/remove
            if remove:
                try:
                    curvalue.remove(itemid)
                except ValueError:
                    raise HyperdbValueError, _('property %s: %r is not ' \
                        'currently an element')%(propname, item)
            else:
                newvalue.append(itemid)
                if itemid not in curvalue:
                    curvalue.append(itemid)

        # that's it, set the new Multilink property value,
        # or overwrite it completely
        if do_set:
            value = newvalue
        else:
            value = curvalue

        # TODO: one day, we'll switch to numeric ids and this will be
        # unnecessary :(
        value = [int(x) for x in value]
        value.sort()
        value = [str(x) for x in value]
        return value

    def sort_repr (self, cls, val, name):
        if not val:
            return val
        op = cls.labelprop()
        if op == 'id':
            return [int(cls.get(v, op)) for v in val]
        return [cls.get(v, op) for v in val]

class Boolean(_Type):
    """An object designating a boolean property"""
    def from_raw(self, value, **kw):
        value = value.strip()
        # checked is a common HTML checkbox value
        value = value.lower() in ('checked', 'yes', 'true', 'on', '1')
        return value

class Number(_Type):
    """An object designating a numeric property"""
    def from_raw(self, value, **kw):
        value = value.strip()
        try:
            value = float(value)
        except ValueError:
            raise HyperdbValueError, _('property %s: %r is not a number')%(
                kw['propname'], value)
        return value
#
# Support for splitting designators
#
class DesignatorError(ValueError):
    pass
def splitDesignator(designator, dre=re.compile(r'([^\d]+)(\d+)')):
    """ Take a foo123 and return ('foo', 123)
    """
    m = dre.match(designator)
    if m is None:
        raise DesignatorError, _('"%s" not a node designator')%designator
    return m.group(1), m.group(2)

class Proptree(object):
    """ Simple tree data structure for optimizing searching of
    properties. Each node in the tree represents a roundup Class
    Property that has to be navigated for finding the given search
    or sort properties. The need_for attribute is used for
    distinguishing nodes in the tree used for sorting, searching or
    retrieval: The attribute is a dictionary containing one or several
    of the values 'sort', 'search', 'retrieve'.

    The Proptree is also used for transitively searching attributes for
    backends that do not support transitive search (e.g. anydbm). The
    _val attribute with set_val is used for this.
    """

    def __init__(self, db, cls, name, props, parent=None, retr=False):
        self.db = db
        self.name = name
        self.props = props
        self.parent = parent
        self._val = None
        self.has_values = False
        self.cls = cls
        self.classname = None
        self.uniqname = None
        self.children = []
        self.sortattr = []
        self.propdict = {}
        self.need_for = {'search' : True}
        self.sort_direction = None
        self.sort_ids = None
        self.sort_ids_needed = False
        self.sort_result = None
        self.attr_sort_done = False
        self.tree_sort_done = False
        self.propclass = None
        self.orderby = []
        self.sql_idx = None # index of retrieved column in sql result
        if parent:
            self.root = parent.root
            self.depth = parent.depth + 1
        else:
            self.root = self
            self.seqno = 1
            self.depth = 0
            self.need_for['sort'] = True
        self.id = self.root.seqno
        self.root.seqno += 1
        if self.cls:
            self.classname = self.cls.classname
            self.uniqname = '%s%s' % (self.cls.classname, self.id)
        if not self.parent:
            self.uniqname = self.cls.classname
        if retr:
            self.append_retr_props()

    def append(self, name, need_for='search', retr=False):
        """Append a property to self.children. Will create a new
        propclass for the child.
        """
        if name in self.propdict:
            pt = self.propdict[name]
            pt.need_for[need_for] = True
            if retr and isinstance(pt.propclass, Link):
                pt.append_retr_props()
            return pt
        propclass = self.props[name]
        cls = None
        props = None
        if isinstance(propclass, (Link, Multilink)):
            cls = self.db.getclass(propclass.classname)
            props = cls.getprops()
        child = self.__class__(self.db, cls, name, props, parent = self)
        child.need_for = {need_for : True}
        child.propclass = propclass
        self.children.append(child)
        self.propdict[name] = child
        if retr and isinstance(child.propclass, Link):
            child.append_retr_props()
        return child

    def append_retr_props(self):
        """Append properties for retrieval."""
        for name, prop in self.cls.getprops(protected=1).iteritems():
            if isinstance(prop, Multilink):
                continue
            self.append(name, need_for='retrieve')

    def compute_sort_done(self, mlseen=False):
        """ Recursively check if attribute is needed for sorting
        ('sort' in self.need_for) or all children have tree_sort_done set and
        sort_ids_needed unset: set self.tree_sort_done if one of the conditions
        holds. Also remove sort_ids_needed recursively once having seen a
        Multilink.
        """
        if isinstance (self.propclass, Multilink):
            mlseen = True
        if mlseen:
            self.sort_ids_needed = False
        self.tree_sort_done = True
        for p in self.children:
            p.compute_sort_done(mlseen)
            if not p.tree_sort_done:
                self.tree_sort_done = False
        if 'sort' not in self.need_for:
            self.tree_sort_done = True
        if mlseen:
            self.tree_sort_done = False

    def ancestors(self):
        p = self
        while p.parent:
            yield p
            p = p.parent

    def search(self, search_matches=None, sort=True):
        """ Recursively search for the given properties in a proptree.
        Once all properties are non-transitive, the search generates a
        simple _filter call which does the real work
        """
        filterspec = {}
        for p in self.children:
            if 'search' in p.need_for:
                if p.children:
                    p.search(sort = False)
                filterspec[p.name] = p.val
        self.val = self.cls._filter(search_matches, filterspec, sort and self)
        return self.val

    def sort (self, ids=None):
        """ Sort ids by the order information stored in self. With
        optimisations: Some order attributes may be precomputed (by the
        backend) and some properties may already be sorted.
        """
        if ids is None:
            ids = self.val
        if self.sortattr and [s for s in self.sortattr if not s.attr_sort_done]:
            return self._searchsort(ids, True, True)
        return ids

    def sortable_children(self, intermediate=False):
        """ All children needed for sorting. If intermediate is True,
        intermediate nodes (not being a sort attribute) are returned,
        too.
        """
        return [p for p in self.children
                if 'sort' in p.need_for and (intermediate or p.sort_direction)]

    def __iter__(self):
        """ Yield nodes in depth-first order -- visited nodes first """
        for p in self.children:
            yield p
            for c in p:
                yield c

    def _get (self, ids):
        """Lookup given ids -- possibly a list of list. We recurse until
        we have a list of ids.
        """
        if not ids:
            return ids
        if isinstance (ids[0], list):
            cids = [self._get(i) for i in ids]
        else:
            cids = [i and self.parent.cls.get(i, self.name) for i in ids]
            if self.sortattr:
                cids = [self._searchsort(i, False, True) for i in cids]
        return cids

    def _searchsort(self, ids=None, update=True, dosort=True):
        """ Recursively compute the sort attributes. Note that ids
        may be a deeply nested list of lists of ids if several
        multilinks are encountered on the way from the root to an
        individual attribute. We make sure that everything is properly
        sorted on the way up. Note that the individual backend may
        already have precomputed self.result or self.sort_ids. In this
        case we do nothing for existing sa.result and recurse further if
        self.sort_ids is available.

        Yech, Multilinks: This gets especially complicated if somebody
        sorts by different attributes of the same multilink (or
        transitively across several multilinks). My use-case is sorting
        by issue.messages.author and (reverse) by issue.messages.date.
        In this case we sort the messages by author and date and use
        this sorted list twice for sorting issues. This means that
        issues are sorted by author and then by the time of the messages
        *of this author*. Probably what the user intends in that case,
        so we do *not* use two sorted lists of messages, one sorted by
        author and one sorted by date for sorting issues.
        """
        for pt in self.sortable_children(intermediate = True):
            # ids can be an empty list
            if pt.tree_sort_done or not ids:
                continue
            if pt.sort_ids: # cached or computed by backend
                cids = pt.sort_ids
            else:
                cids = pt._get(ids)
            if pt.sort_direction and not pt.sort_result:
                sortrep = pt.propclass.sort_repr
                pt.sort_result = pt._sort_repr(sortrep, cids)
            pt.sort_ids = cids
            if pt.children:
                pt._searchsort(cids, update, False)
        if self.sortattr and dosort:
            ids = self._sort(ids)
        if not update:
            for pt in self.sortable_children(intermediate = True):
                pt.sort_ids = None
            for pt in self.sortattr:
                pt.sort_result = None
        return ids

    def _set_val(self, val):
        """Check if self._val is already defined. If yes, we compute the
        intersection of the old and the new value(s)
        """
        if self.has_values:
            v = self._val
            if not isinstance(self._val, type([])):
                v = [self._val]
            vals = set(v)
            vals.intersection_update(val)
            self._val = [v for v in vals]
        else:
            self._val = val
        self.has_values = True

    val = property(lambda self: self._val, _set_val)

    def _sort(self, val):
        """Finally sort by the given sortattr.sort_result. Note that we
        do not sort by attrs having attr_sort_done set. The caller is
        responsible for setting attr_sort_done only for trailing
        attributes (otherwise the sort order is wrong). Since pythons
        sort is stable, we can sort already sorted lists without
        destroying the sort-order for items that compare equal with the
        current sort.

        Sorting-Strategy: We sort repeatedly by different sort-keys from
        right to left. Since pythons sort is stable, we can safely do
        that. An optimisation is a "run-length encoding" of the
        sort-directions: If several sort attributes sort in the same
        direction we can combine them into a single sort. Note that
        repeated sorting is probably more efficient than using
        compare-methods in python due to the overhead added by compare
        methods.
        """
        if not val:
            return val
        sortattr = []
        directions = []
        dir_idx = []
        idx = 0
        curdir = None
        for sa in self.sortattr:
            if sa.attr_sort_done:
                break
            if sortattr:
                assert len(sortattr[0]) == len(sa.sort_result)
            sortattr.append (sa.sort_result)
            if curdir != sa.sort_direction:
                dir_idx.append (idx)
                directions.append (sa.sort_direction)
                curdir = sa.sort_direction
            idx += 1
        sortattr.append (val)
        sortattr = zip (*sortattr)
        for dir, i in reversed(zip(directions, dir_idx)):
            rev = dir == '-'
            sortattr = sorted (sortattr, key = lambda x:x[i:idx], reverse = rev)
            idx = i
        return [x[-1] for x in sortattr]

    def _sort_repr(self, sortrep, ids):
        """Call sortrep for given ids -- possibly a list of list. We
        recurse until we have a list of ids.
        """
        if not ids:
            return ids
        if isinstance (ids[0], list):
            res = [self._sort_repr(sortrep, i) for i in ids]
        else:
            res = [sortrep(self.cls, i, self.name) for i in ids]
        return res

    def __repr__(self):
        r = ["proptree:" + self.name]
        for n in self:
            r.append("proptree:" + "    " * n.depth + n.name)
        return '\n'.join(r)
    __str__ = __repr__

#
# the base Database class
#
class DatabaseError(ValueError):
    """Error to be raised when there is some problem in the database code
    """
    pass
class Database:
    """A database for storing records containing flexible data types.

This class defines a hyperdatabase storage layer, which the Classes use to
store their data.


Transactions
------------
The Database should support transactions through the commit() and
rollback() methods. All other Database methods should be transaction-aware,
using data from the current transaction before looking up the database.

An implementation must provide an override for the get() method so that the
in-database value is returned in preference to the in-transaction value.
This is necessary to determine if any values have changed during a
transaction.


Implementation
--------------

All methods except __repr__ must be implemented by a concrete backend Database.

"""

    # flag to set on retired entries
    RETIRED_FLAG = '__hyperdb_retired'

    BACKEND_MISSING_STRING = None
    BACKEND_MISSING_NUMBER = None
    BACKEND_MISSING_BOOLEAN = None

    def __init__(self, config, journaltag=None):
        """Open a hyperdatabase given a specifier to some storage.

        The 'storagelocator' is obtained from config.DATABASE.
        The meaning of 'storagelocator' depends on the particular
        implementation of the hyperdatabase.  It could be a file name,
        a directory path, a socket descriptor for a connection to a
        database over the network, etc.

        The 'journaltag' is a token that will be attached to the journal
        entries for any edits done on the database.  If 'journaltag' is
        None, the database is opened in read-only mode: the Class.create(),
        Class.set(), and Class.retire() methods are disabled.
        """
        raise NotImplementedError

    def post_init(self):
        """Called once the schema initialisation has finished.
           If 'refresh' is true, we want to rebuild the backend
           structures.
        """
        raise NotImplementedError

    def refresh_database(self):
        """Called to indicate that the backend should rebuild all tables
           and structures. Not called in normal usage."""
        raise NotImplementedError

    def __getattr__(self, classname):
        """A convenient way of calling self.getclass(classname)."""
        raise NotImplementedError

    def addclass(self, cl):
        """Add a Class to the hyperdatabase.
        """
        raise NotImplementedError

    def getclasses(self):
        """Return a list of the names of all existing classes."""
        raise NotImplementedError

    def getclass(self, classname):
        """Get the Class object representing a particular class.

        If 'classname' is not a valid class name, a KeyError is raised.
        """
        raise NotImplementedError

    def clear(self):
        """Delete all database contents.
        """
        raise NotImplementedError

    def getclassdb(self, classname, mode='r'):
        """Obtain a connection to the class db that will be used for
           multiple actions.
        """
        raise NotImplementedError

    def addnode(self, classname, nodeid, node):
        """Add the specified node to its class's db.
        """
        raise NotImplementedError

    def serialise(self, classname, node):
        """Copy the node contents, converting non-marshallable data into
           marshallable data.
        """
        return node

    def setnode(self, classname, nodeid, node):
        """Change the specified node.
        """
        raise NotImplementedError

    def unserialise(self, classname, node):
        """Decode the marshalled node data
        """
        return node

    def getnode(self, classname, nodeid):
        """Get a node from the database.

        'cache' exists for backwards compatibility, and is not used.
        """
        raise NotImplementedError

    def hasnode(self, classname, nodeid):
        """Determine if the database has a given node.
        """
        raise NotImplementedError

    def countnodes(self, classname):
        """Count the number of nodes that exist for a particular Class.
        """
        raise NotImplementedError

    def storefile(self, classname, nodeid, property, content):
        """Store the content of the file in the database.

           The property may be None, in which case the filename does not
           indicate which property is being saved.
        """
        raise NotImplementedError

    def getfile(self, classname, nodeid, property):
        """Get the content of the file in the database.
        """
        raise NotImplementedError

    def addjournal(self, classname, nodeid, action, params):
        """ Journal the Action
        'action' may be:

            'create' or 'set' -- 'params' is a dictionary of property values
            'link' or 'unlink' -- 'params' is (classname, nodeid, propname)
            'retire' -- 'params' is None
        """
        raise NotImplementedError

    def getjournal(self, classname, nodeid):
        """ get the journal for id
        """
        raise NotImplementedError

    def pack(self, pack_before):
        """ pack the database
        """
        raise NotImplementedError

    def commit(self):
        """ Commit the current transactions.

        Save all data changed since the database was opened or since the
        last commit() or rollback().

        fail_ok indicates that the commit is allowed to fail. This is used
        in the web interface when committing cleaning of the session
        database. We don't care if there's a concurrency issue there.

        The only backend this seems to affect is postgres.
        """
        raise NotImplementedError

    def rollback(self):
        """ Reverse all actions from the current transaction.

        Undo all the changes made since the database was opened or the last
        commit() or rollback() was performed.
        """
        raise NotImplementedError

    def close(self):
        """Close the database.

        This method must be called at the end of processing.

        """

def iter_roles(roles):
    ''' handle the text processing of turning the roles list
        into something python can use more easily
    '''
    if not roles or not roles.strip():
        raise StopIteration, "Empty roles given"
    for role in [x.lower().strip() for x in roles.split(',')]:
        yield role


#
# The base Class class
#
class Class:
    """ The handle to a particular class of nodes in a hyperdatabase.

        All methods except __repr__ and getnode must be implemented by a
        concrete backend Class.
    """

    def __init__(self, db, classname, **properties):
        """Create a new class with a given name and property specification.

        'classname' must not collide with the name of an existing class,
        or a ValueError is raised.  The keyword arguments in 'properties'
        must map names to property objects, or a TypeError is raised.
        """
        for name in 'creation activity creator actor'.split():
            if properties.has_key(name):
                raise ValueError, '"creation", "activity", "creator" and '\
                    '"actor" are reserved'

        self.classname = classname
        self.properties = properties
        self.db = weakref.proxy(db)       # use a weak ref to avoid circularity
        self.key = ''

        # should we journal changes (default yes)
        self.do_journal = 1

        # do the db-related init stuff
        db.addclass(self)

        actions = "create set retire restore".split()
        self.auditors = dict([(a, PrioList()) for a in actions])
        self.reactors = dict([(a, PrioList()) for a in actions])

    def __repr__(self):
        """Slightly more useful representation
        """
        return '<hyperdb.Class "%s">'%self.classname

    # Editing nodes:

    def create(self, **propvalues):
        """Create a new node of this class and return its id.

        The keyword arguments in 'propvalues' map property names to values.

        The values of arguments must be acceptable for the types of their
        corresponding properties or a TypeError is raised.

        If this class has a key property, it must be present and its value
        must not collide with other key strings or a ValueError is raised.

        Any other properties on this class that are missing from the
        'propvalues' dictionary are set to None.

        If an id in a link or multilink property does not refer to a valid
        node, an IndexError is raised.
        """
        raise NotImplementedError

    _marker = []
    def get(self, nodeid, propname, default=_marker, cache=1):
        """Get the value of a property on an existing node of this class.

        'nodeid' must be the id of an existing node of this class or an
        IndexError is raised.  'propname' must be the name of a property
        of this class or a KeyError is raised.

        'cache' exists for backwards compatibility, and is not used.
        """
        raise NotImplementedError

    # not in spec
    def getnode(self, nodeid):
        """ Return a convenience wrapper for the node.

        'nodeid' must be the id of an existing node of this class or an
        IndexError is raised.

        'cache' exists for backwards compatibility, and is not used.
        """
        return Node(self, nodeid)

    def getnodeids(self, retired=None):
        """Retrieve all the ids of the nodes for a particular Class.
        """
        raise NotImplementedError

    def set(self, nodeid, **propvalues):
        """Modify a property on an existing node of this class.

        'nodeid' must be the id of an existing node of this class or an
        IndexError is raised.

        Each key in 'propvalues' must be the name of a property of this
        class or a KeyError is raised.

        All values in 'propvalues' must be acceptable types for their
        corresponding properties or a TypeError is raised.

        If the value of the key property is set, it must not collide with
        other key strings or a ValueError is raised.

        If the value of a Link or Multilink property contains an invalid
        node id, a ValueError is raised.
        """
        raise NotImplementedError

    def retire(self, nodeid):
        """Retire a node.

        The properties on the node remain available from the get() method,
        and the node's id is never reused.

        Retired nodes are not returned by the find(), list(), or lookup()
        methods, and other nodes may reuse the values of their key properties.
        """
        raise NotImplementedError

    def restore(self, nodeid):
        """Restpre a retired node.

        Make node available for all operations like it was before retirement.
        """
        raise NotImplementedError

    def is_retired(self, nodeid):
        """Return true if the node is rerired
        """
        raise NotImplementedError

    def destroy(self, nodeid):
        """Destroy a node.

        WARNING: this method should never be used except in extremely rare
                 situations where there could never be links to the node being
                 deleted

        WARNING: use retire() instead

        WARNING: the properties of this node will not be available ever again

        WARNING: really, use retire() instead

        Well, I think that's enough warnings. This method exists mostly to
        support the session storage of the cgi interface.

        The node is completely removed from the hyperdb, including all journal
        entries. It will no longer be available, and will generally break code
        if there are any references to the node.
        """

    def history(self, nodeid):
        """Retrieve the journal of edits on a particular node.

        'nodeid' must be the id of an existing node of this class or an
        IndexError is raised.

        The returned list contains tuples of the form

            (date, tag, action, params)

        'date' is a Timestamp object specifying the time of the change and
        'tag' is the journaltag specified when the database was opened.
        """
        if not self.do_journal:
            raise ValueError('Journalling is disabled for this class')
        return self.db.getjournal(self.classname, nodeid)

    # Locating nodes:
    def hasnode(self, nodeid):
        """Determine if the given nodeid actually exists
        """
        raise NotImplementedError

    def setkey(self, propname):
        """Select a String property of this class to be the key property.

        'propname' must be the name of a String property of this class or
        None, or a TypeError is raised.  The values of the key property on
        all existing nodes must be unique or a ValueError is raised.
        """
        raise NotImplementedError

    def setlabelprop(self, labelprop):
        """Set the label property. Used for override of labelprop
           resolution order.
        """
        if labelprop not in self.getprops():
            raise ValueError, _("Not a property name: %s") % labelprop
        self._labelprop = labelprop

    def setorderprop(self, orderprop):
        """Set the order property. Used for override of orderprop
           resolution order
        """
        if orderprop not in self.getprops():
            raise ValueError, _("Not a property name: %s") % orderprop
        self._orderprop = orderprop

    def getkey(self):
        """Return the name of the key property for this class or None."""
        raise NotImplementedError

    def labelprop(self, default_to_id=0):
        """Return the property name for a label for the given node.

        This method attempts to generate a consistent label for the node.
        It tries the following in order:

        0. self._labelprop if set
        1. key property
        2. "name" property
        3. "title" property
        4. first property from the sorted property name list
        """
        if hasattr(self, '_labelprop'):
            return self._labelprop
        k = self.getkey()
        if  k:
            return k
        props = self.getprops()
        if props.has_key('name'):
            return 'name'
        elif props.has_key('title'):
            return 'title'
        if default_to_id:
            return 'id'
        props = props.keys()
        props.sort()
        return props[0]

    def orderprop(self):
        """Return the property name to use for sorting for the given node.

        This method computes the property for sorting.
        It tries the following in order:

        0. self._orderprop if set
        1. "order" property
        2. self.labelprop()
        """

        if hasattr(self, '_orderprop'):
            return self._orderprop
        props = self.getprops()
        if props.has_key('order'):
            return 'order'
        return self.labelprop()

    def lookup(self, keyvalue):
        """Locate a particular node by its key property and return its id.

        If this class has no key property, a TypeError is raised.  If the
        'keyvalue' matches one of the values for the key property among
        the nodes in this class, the matching node's id is returned;
        otherwise a KeyError is raised.
        """
        raise NotImplementedError

    def find(self, **propspec):
        """Get the ids of nodes in this class which link to the given nodes.

        'propspec' consists of keyword args propname={nodeid:1,}
        'propname' must be the name of a property in this class, or a
        KeyError is raised.  That property must be a Link or Multilink
        property, or a TypeError is raised.

        Any node in this class whose 'propname' property links to any of the
        nodeids will be returned. Used by the full text indexing, which knows
        that "foo" occurs in msg1, msg3 and file7, so we have hits on these
        issues:

            db.issue.find(messages={'1':1,'3':1}, files={'7':1})
        """
        raise NotImplementedError

    def _filter(self, search_matches, filterspec, sort=(None,None),
            group=(None,None)):
        """For some backends this implements the non-transitive
        search, for more information see the filter method.
        """
        raise NotImplementedError

    def _proptree(self, filterspec, sortattr=[], retr=False):
        """Build a tree of all transitive properties in the given
        filterspec.
        If we retrieve (retr is True) linked items we don't follow
        across multilinks. We also don't follow if the searched value
        can contain NULL values.
        """
        proptree = Proptree(self.db, self, '', self.getprops(), retr=retr)
        for key, v in filterspec.iteritems():
            keys = key.split('.')
            p = proptree
            mlseen = False
            for k in keys:
                if isinstance (p.propclass, Multilink):
                    mlseen = True
                isnull = v == '-1' or v is None
                nullin = isinstance(v, type([])) and ('-1' in v or None in v)
                r = retr and not mlseen and not isnull and not nullin
                p = p.append(k, retr=r)
            p.val = v
        multilinks = {}
        for s in sortattr:
            keys = s[1].split('.')
            p = proptree
            mlseen = False
            for k in keys:
                if isinstance (p.propclass, Multilink):
                    mlseen = True
                r = retr and not mlseen
                p = p.append(k, need_for='sort', retr=r)
                if isinstance (p.propclass, Multilink):
                    multilinks[p] = True
            if p.cls:
                p = p.append(p.cls.orderprop(), need_for='sort')
            if p.sort_direction: # if an orderprop is also specified explicitly
                continue
            p.sort_direction = s[0]
            proptree.sortattr.append (p)
        for p in multilinks.iterkeys():
            sattr = {}
            for c in p:
                if c.sort_direction:
                    sattr [c] = True
            for sa in proptree.sortattr:
                if sa in sattr:
                    p.sortattr.append (sa)
        return proptree

    def get_transitive_prop(self, propname_path, default = None):
        """Expand a transitive property (individual property names
        separated by '.' into a new property at the end of the path. If
        one of the names does not refer to a valid property, we return
        None.
        Example propname_path (for class issue): "messages.author"
        """
        props = self.db.getclass(self.classname).getprops()
        for k in propname_path.split('.'):
            try:
                prop = props[k]
            except (KeyError, TypeError):
                return default
            cl = getattr(prop, 'classname', None)
            props = None
            if cl:
                props = self.db.getclass(cl).getprops()
        return prop

    def _sortattr(self, sort=[], group=[]):
        """Build a single list of sort attributes in the correct order
        with sanity checks (no duplicate properties) included. Always
        sort last by id -- if id is not already in sortattr.
        """
        seen = {}
        sortattr = []
        for srt in group, sort:
            if not isinstance(srt, list):
                srt = [srt]
            for s in srt:
                if s[1] and s[1] not in seen:
                    sortattr.append((s[0] or '+', s[1]))
                    seen[s[1]] = True
        if 'id' not in seen :
            sortattr.append(('+', 'id'))
        return sortattr

    def filter(self, search_matches, filterspec, sort=[], group=[]):
        """Return a list of the ids of the active nodes in this class that
        match the 'filter' spec, sorted by the group spec and then the
        sort spec.

        "filterspec" is {propname: value(s)}

        "sort" and "group" are [(dir, prop), ...] where dir is '+', '-'
        or None and prop is a prop name or None. Note that for
        backward-compatibility reasons a single (dir, prop) tuple is
        also allowed.

        "search_matches" is a container type

        The filter must match all properties specificed. If the property
        value to match is a list:

        1. String properties must match all elements in the list, and
        2. Other properties must match any of the elements in the list.

        Note that now the propname in filterspec and prop in a
        sort/group spec may be transitive, i.e., it may contain
        properties of the form link.link.link.name, e.g. you can search
        for all issues where a message was added by a certain user in
        the last week with a filterspec of
        {'messages.author' : '42', 'messages.creation' : '.-1w;'}

        Implementation note:
        This implements a non-optimized version of Transitive search
        using _filter implemented in a backend class. A more efficient
        version can be implemented in the individual backends -- e.g.,
        an SQL backend will want to create a single SQL statement and
        override the filter method instead of implementing _filter.
        """
        sortattr = self._sortattr(sort = sort, group = group)
        proptree = self._proptree(filterspec, sortattr)
        proptree.search(search_matches)
        return proptree.sort()

    # non-optimized filter_iter, a backend may chose to implement a
    # better version that provides a real iterator that pre-fills the
    # cache for each id returned. Note that the filter_iter doesn't
    # promise to correctly sort by multilink (which isn't sane to do
    # anyway).
    filter_iter = filter

    def count(self):
        """Get the number of nodes in this class.

        If the returned integer is 'numnodes', the ids of all the nodes
        in this class run from 1 to numnodes, and numnodes+1 will be the
        id of the next node to be created in this class.
        """
        raise NotImplementedError

    # Manipulating properties:
    def getprops(self, protected=1):
        """Return a dictionary mapping property names to property objects.
           If the "protected" flag is true, we include protected properties -
           those which may not be modified.
        """
        raise NotImplementedError

    def get_required_props(self, propnames = []):
        """Return a dict of property names mapping to property objects.
        All properties that have the "required" flag set will be
        returned in addition to all properties in the propnames
        parameter.
        """
        props = self.getprops(protected = False)
        pdict = dict([(p, props[p]) for p in propnames])
        pdict.update([(k, v) for k, v in props.iteritems() if v.required])
        return pdict

    def addprop(self, **properties):
        """Add properties to this class.

        The keyword arguments in 'properties' must map names to property
        objects, or a TypeError is raised.  None of the keys in 'properties'
        may collide with the names of existing properties, or a ValueError
        is raised before any properties have been added.
        """
        raise NotImplementedError

    def index(self, nodeid):
        """Add (or refresh) the node to search indexes"""
        raise NotImplementedError

    #
    # Detector interface
    #
    def audit(self, event, detector, priority = 100):
        """Register an auditor detector"""
        self.auditors[event].append((priority, detector.__name__, detector))

    def fireAuditors(self, event, nodeid, newvalues):
        """Fire all registered auditors"""
        for prio, name, audit in self.auditors[event]:
            audit(self.db, self, nodeid, newvalues)

    def react(self, event, detector, priority = 100):
        """Register a reactor detector"""
        self.reactors[event].append((priority, detector.__name__, detector))

    def fireReactors(self, event, nodeid, oldvalues):
        """Fire all registered reactors"""
        for prio, name, react in self.reactors[event]:
            react(self.db, self, nodeid, oldvalues)

    #
    # import / export support
    #
    def export_propnames(self):
        """List the property names for export from this Class"""
        propnames = self.getprops().keys()
        propnames.sort()
        return propnames

    def import_journals(self, entries):
        """Import a class's journal.

        Uses setjournal() to set the journal for each item.
        Strategy for import: Sort first by id, then import journals for
        each id, this way the memory footprint is a lot smaller than the
        initial implementation which stored everything in a big hash by
        id and then proceeded to import journals for each id."""
        properties = self.getprops()
        a = []
        for l in entries:
            # first element in sorted list is the (numeric) id
            # in python2.4 and up we would use sorted with a key...
            a.append ((int (l [0].strip ("'")), l))
        a.sort ()


        last = 0
        r = []
        for n, l in a:
            nodeid, jdate, user, action, params = map(eval, l)
            assert (str(n) == nodeid)
            if n != last:
                if r:
                    self.db.setjournal(self.classname, str(last), r)
                last = n
                r = []

            if action == 'set':
                for propname, value in params.iteritems():
                    prop = properties[propname]
                    if value is None:
                        pass
                    elif isinstance(prop, Date):
                        value = date.Date(value)
                    elif isinstance(prop, Interval):
                        value = date.Interval(value)
                    elif isinstance(prop, Password):
                        value = password.JournalPassword(encrypted=value)
                    params[propname] = value
            elif action == 'create' and params:
                # old tracker with data stored in the create!
                params = {}
            r.append((nodeid, date.Date(jdate), user, action, params))
        if r:
            self.db.setjournal(self.classname, nodeid, r)

    #
    # convenience methods
    #
    def get_roles(self, nodeid):
        """Return iterator for all roles for this nodeid.

           Yields string-processed roles.
           This method can be overridden to provide a hook where we can
           insert other permission models (e.g. get roles from database)
           In standard schemas only a user has a roles property but
           this may be different in customized schemas.
           Note that this is the *central place* where role
           processing happens!
        """
        node = self.db.getnode(self.classname, nodeid)
        return iter_roles(node['roles'])

    def has_role(self, nodeid, *roles):
        '''See if this node has any roles that appear in roles.

           For convenience reasons we take a list.
           In standard schemas only a user has a roles property but
           this may be different in customized schemas.
        '''
        roles = dict.fromkeys ([r.strip().lower() for r in roles])
        for role in self.get_roles(nodeid):
            if role in roles:
                return True
        return False


class HyperdbValueError(ValueError):
    """ Error converting a raw value into a Hyperdb value """
    pass

def convertLinkValue(db, propname, prop, value, idre=re.compile('^\d+$')):
    """ Convert the link value (may be id or key value) to an id value. """
    linkcl = db.classes[prop.classname]
    if not idre.match(value):
        if linkcl.getkey():
            try:
                value = linkcl.lookup(value)
            except KeyError, message:
                raise HyperdbValueError, _('property %s: %r is not a %s.')%(
                    propname, value, prop.classname)
        else:
            raise HyperdbValueError, _('you may only enter ID values '\
                'for property %s')%propname
    return value

def fixNewlines(text):
    """ Homogenise line endings.

        Different web clients send different line ending values, but
        other systems (eg. email) don't necessarily handle those line
        endings. Our solution is to convert all line endings to LF.
    """
    text = text.replace('\r\n', '\n')
    return text.replace('\r', '\n')

def rawToHyperdb(db, klass, itemid, propname, value, **kw):
    """ Convert the raw (user-input) value to a hyperdb-storable value. The
        value is for the "propname" property on itemid (may be None for a
        new item) of "klass" in "db".

        The value is usually a string, but in the case of multilink inputs
        it may be either a list of strings or a string with comma-separated
        values.
    """
    properties = klass.getprops()

    # ensure it's a valid property name
    propname = propname.strip()
    try:
        proptype =  properties[propname]
    except KeyError:
        raise HyperdbValueError, _('%r is not a property of %s')%(propname,
            klass.classname)

    # if we got a string, strip it now
    if isinstance(value, type('')):
        value = value.strip()

    # convert the input value to a real property value
    value = proptype.from_raw(value, db=db, klass=klass,
        propname=propname, itemid=itemid, **kw)

    return value

class FileClass:
    """ A class that requires the "content" property and stores it on
        disk.
    """
    default_mime_type = 'text/plain'

    def __init__(self, db, classname, **properties):
        """The newly-created class automatically includes the "content"
        property.
        """
        if not properties.has_key('content'):
            properties['content'] = String(indexme='yes')

    def export_propnames(self):
        """ Don't export the "content" property
        """
        propnames = self.getprops().keys()
        propnames.remove('content')
        propnames.sort()
        return propnames

    def exportFilename(self, dirname, nodeid):
        subdir_filename = self.db.subdirFilename(self.classname, nodeid)
        return os.path.join(dirname, self.classname+'-files', subdir_filename)

    def export_files(self, dirname, nodeid):
        """ Export the "content" property as a file, not csv column
        """
        source = self.db.filename(self.classname, nodeid)

        dest = self.exportFilename(dirname, nodeid)
        ensureParentsExist(dest)
        shutil.copyfile(source, dest)

    def import_files(self, dirname, nodeid):
        """ Import the "content" property as a file
        """
        source = self.exportFilename(dirname, nodeid)

        dest = self.db.filename(self.classname, nodeid, create=1)
        ensureParentsExist(dest)
        shutil.copyfile(source, dest)

        mime_type = None
        props = self.getprops()
        if props.has_key('type'):
            mime_type = self.get(nodeid, 'type')
        if not mime_type:
            mime_type = self.default_mime_type
        if props['content'].indexme:
            self.db.indexer.add_text((self.classname, nodeid, 'content'),
                self.get(nodeid, 'content'), mime_type)

class Node:
    """ A convenience wrapper for the given node
    """
    def __init__(self, cl, nodeid, cache=1):
        self.__dict__['cl'] = cl
        self.__dict__['nodeid'] = nodeid
    def keys(self, protected=1):
        return self.cl.getprops(protected=protected).keys()
    def values(self, protected=1):
        l = []
        for name in self.cl.getprops(protected=protected).keys():
            l.append(self.cl.get(self.nodeid, name))
        return l
    def items(self, protected=1):
        l = []
        for name in self.cl.getprops(protected=protected).keys():
            l.append((name, self.cl.get(self.nodeid, name)))
        return l
    def has_key(self, name):
        return self.cl.getprops().has_key(name)
    def get(self, name, default=None):
        if self.has_key(name):
            return self[name]
        else:
            return default
    def __getattr__(self, name):
        if self.__dict__.has_key(name):
            return self.__dict__[name]
        try:
            return self.cl.get(self.nodeid, name)
        except KeyError, value:
            # we trap this but re-raise it as AttributeError - all other
            # exceptions should pass through untrapped
            pass
        # nope, no such attribute
        raise AttributeError, str(value)
    def __getitem__(self, name):
        return self.cl.get(self.nodeid, name)
    def __setattr__(self, name, value):
        try:
            return self.cl.set(self.nodeid, **{name: value})
        except KeyError, value:
            raise AttributeError, str(value)
    def __setitem__(self, name, value):
        self.cl.set(self.nodeid, **{name: value})
    def history(self):
        return self.cl.history(self.nodeid)
    def retire(self):
        return self.cl.retire(self.nodeid)


def Choice(name, db, *options):
    """Quick helper to create a simple class with choices
    """
    cl = Class(db, name, name=String(), order=String())
    for i in range(len(options)):
        cl.create(name=options[i], order=i)
    return Link(name)

# vim: set filetype=python sts=4 sw=4 et si :