private final Map<String, Subroutine> subroutines = new HashMap<>();

private Reader input;

private Writer output;

private Writer error;

private boolean theMapHasToBeFilled = true;

private Context ctx;

public Engine() {

}

@Override

public Reader getInput() {

return input;

}

@Override

public void setInput(final Reader input) {

this.input = input;

}

@Override

public Writer getOutput() {

return output;

}

@Override

public void setOutput(final Writer output) {

this.output = output;

}

@Override

public Writer getErrorOutput() {

return error;

}

@Override

public void setErrorOutput(final Writer error) {

this.error = error;

}

private void loadHelper(final Reader reader) throws ScriptBasicException {

loadHelper(reader, null);

}

private void loadHelper(final String fileName, final SourceProvider sourceProvider) throws ScriptBasicException {

try {

final var sourceReader = sourceProvider.get(fileName);

loadHelper(sourceReader);

} catch (final IOException e) {

throw new ScriptBasicException(e);

}

}

private void loadHelper(final Reader reader, final String fileName) throws ScriptBasicException {

try {

ctx = ContextBuilder.from(ctx, reader, input, output, error);

ctx.interpreter.setProgram(ctx.syntaxAnalyzer.analyze());

} catch (final AnalysisException e) {

throw new ScriptBasicException(e);

}

}

private void loadHelper(final SourceReader sourceReader) throws ScriptBasicException {

try {

ctx = ContextBuilder.from(ctx, sourceReader, input, output, error);

ctx.interpreter.setProgram(ctx.syntaxAnalyzer.analyze());

} catch (final AnalysisException e) {

throw new ScriptBasicException(e);

}

}

@Override

public ScriptBasic execute() throws ScriptBasicException {

assertCtxInitialized();

ctx.interpreter.execute();

return this;

}

private void assertCtxInitialized() throws ScriptBasicException {

if (ctx == null) {

throw new ScriptBasicException("Interpreter was not properly initialized.");

}

}

@Override

public ScriptBasic load(final String sourceCode) throws ScriptBasicException {

loadHelper(new StringReader(sourceCode));

return this;

}

@Override

public ScriptBasic eval(final String sourceCode) throws ScriptBasicException {

load(sourceCode);

execute();

return this;

}

@Override

public ScriptBasic load(final Reader reader) throws ScriptBasicException {

loadHelper(reader);

return this;

}

@Override

public ScriptBasic eval(final Reader reader) throws ScriptBasicException {

load(reader);

execute();

return this;

}

@Override

public ScriptBasic load(final File sourceFile) throws ScriptBasicException {

try {

loadHelper(new FileReader(sourceFile),

sourceFile.getAbsolutePath());

} catch (final FileNotFoundException e) {

throw new ScriptBasicException(e);

}

return this;

}

@Override

public ScriptBasic eval(final File sourceFile) throws ScriptBasicException {

load(sourceFile);

execute();

return this;

}

@Override

public ScriptBasic load(final String sourceFileName, final String... path)

throws ScriptBasicException {

final var sourceProvider = new FileSourceProvider();

final var sourcePath = new BasicSourcePath();

for (final String p : path) {

sourcePath.add(p);

}

sourceProvider.setSourcePath(sourcePath);

loadHelper(sourceFileName, sourceProvider);

return this;

}

@Override

public ScriptBasic eval(final String sourceFileName, final String... path)

throws ScriptBasicException {

load(sourceFileName, path);

execute();

return this;

}

@Override

public ScriptBasic load(final String sourceFileName, final SourcePath path)

throws ScriptBasicException {

final var sourceProvider = new FileSourceProvider();

sourceProvider.setSourcePath(path);

loadHelper(sourceFileName, sourceProvider);

return this;

}

@Override

public ScriptBasic eval(final String sourceFileName, final SourcePath path)

throws ScriptBasicException {

load(sourceFileName, path);

execute();

return this;

}

@Override

public ScriptBasic load(final String sourceName, final SourceProvider provider)

throws ScriptBasicException {

loadHelper(sourceName, provider);

return this;

}

@Override

public ScriptBasic eval(final String sourceName, final SourceProvider provider)

throws ScriptBasicException {

load(sourceName, provider);

execute();

return this;

}

public void setVariable(final String name, final Object value)

throws ScriptBasicException {

ctx = ContextBuilder.from(ctx);

ctx.interpreter.getVariables().setVariable(name,

RightValueUtility.createRightValue(value));

}

@SuppressWarnings("removal")

@Override

public Object getVariable(final String name) throws ScriptBasicException {

return variable(Object.class, name);

}

@Override

public <T> T variable(final Class<T> type, final String name) throws ScriptBasicException {

assertCtxInitialized();

final var result = ctx.interpreter.getVariable(name);

if (result == null || type.isAssignableFrom(result.getClass())) {

return (T) result;

}

throw new ScriptBasicException("Fetching the variable '"

+ name

+ "' casting to type "

+ type.getName()

+ " failed from "

+ result.getClass().getName());

}

@SuppressWarnings("removal")

@Override

public Iterable<String> getVariablesIterator() throws ScriptBasicException {

return variables();

}

@Override

public Iterable<String> variables() throws ScriptBasicException {

assertCtxInitialized();

return ctx.interpreter.getVariables().getGlobalMap().getVariableNameSet();

}

private void SNAFU_SubroutineDoesNotExist(final Exception e) {

throw new BasicInterpreterInternalError(

"An already located subroutine does not exist", e);

}

@Override

public Iterable<Subroutine> subroutines() throws ScriptBasicException {

if (theMapHasToBeFilled) {

assertCtxInitialized();

for (final String s : ctx.interpreter.getProgram().getNamedCommandNames()) {

try {

subroutine(Object.class, s);

} catch (final ScriptBasicException e) {

SNAFU_SubroutineDoesNotExist(e);

}

}

theMapHasToBeFilled = false;

}

return subroutines.values();

}

private CommandSub getCommandSub(final String subroutineName)

throws ScriptBasicException {

assertCtxInitialized();

final var commandSub = ctx.interpreter.getSubroutine(subroutineName);

if (commandSub == null) {

throw new ScriptBasicException("Sobroutine '" + subroutineName

+ "' is not defined in the program");

}

return commandSub;

}

private int getNumberOfArguments(final String subroutineName)

throws ScriptBasicException {

final var commandSub = getCommandSub(subroutineName);

final int size;

if (commandSub.getArguments() != null) {

size = commandSub.getArguments().size();

} else {

size = 0;

}

return size;

}

@Override

public <R> Subroutine<R> subroutine(final String name)

throws ScriptBasicException {

return subroutine(null, name);

}

@Override

public <R> Subroutine<R> subroutine(final Class<R> type, final String name)

throws ScriptBasicException {

if (subroutines.containsKey(name)) {

return subroutines.get(name);

}

final var commandSub = getCommandSub(name);

final var sub = new Sub(type, commandSub.getSubName());

subroutines.put(name, sub);

return sub;

}

public void registerFunction(final String alias,

final Class<?> klass,

final String methodName,

final Class<?>... argumentTypes) throws ScriptBasicException {

ctx = ContextBuilder.from(ctx);

ctx.interpreter.registerJavaMethod(alias, klass, methodName, argumentTypes);

}

@Override

public ScriptBasic registerExtension(final Class<?> klass) {

ctx = ContextBuilder.from(ctx);

ctx.interpreter.registerFunctions(klass);

return this;

}

@Override

public ScriptBasic registerHook(final InterpreterHook hook) {

ctx = ContextBuilder.from(ctx);

ctx.interpreter.registerHook(hook);

return this;

}

@Override

public Configuration getConfiguration() {

ctx = ContextBuilder.from(ctx);

return ctx.configuration;

}

public class Sub<R> implements Subroutine<R> {

private final String name;

private final Class<R> type;

Sub(final Class<R> t, final String n) {

name = n;

type = Objects.requireNonNullElseGet(t, () -> (Class<R>) Object.class);

}

@Override

public int numberOfArguments() {

try {

return Engine.this.getNumberOfArguments(name);

} catch (final ScriptBasicException e) {

SNAFU_SubroutineDoesNotExist(e);

return 0;// will not get here

}

}

@Override

public String name() {

return name;

}

@Override

public R call(final Object... args) throws ScriptBasicException {

assertCtxInitialized();

final var result = ctx.interpreter.call(name, args);

if (type == Void.class && result != null) {

throw new ScriptBasicException("Subroutine '"

+ name

+ "' expected to be Void but returns value of type "

+ type.getName());

}

if (result == null || type.isAssignableFrom(result.getClass())) {

return (R) result;

}

throw new ScriptBasicException("Fetching the return value of subroutine '"

+ name

+ "' casting to type "

+ type.getName()

+ " failed from "

+ result.getClass().getName());

}

@Override

public R call() throws ScriptBasicException {

return call((Object[]) null);

}

}