set -eu

git() { command git -c protocol.file.allow=always "$@"; }

scenario=$1

root=$PWD

git init -q -b master parent

case "$scenario" in

add)

state=$2

remote=$3

if test "$state" != unborn; then git -C parent commit --allow-empty -qm initial; fi

if test "$state" = detached; then git -C parent checkout -q --detach; fi

base=parent

if test "$remote" = origin; then base=remote; fi

if test "$remote" != None; then

url=.

if test "$remote" = origin; then url="$root/$base"; fi

git -C parent remote add origin "$url"

fi

git init -q -b master "$base/source"

git -C "$base/source" commit --allow-empty -qm initial

printf '%s' "$base/source" >source-path

;;

cygwin)

git init -q -b master source

git -C source commit --allow-empty -qm initial

;;

local-remote)

git init -q -b master repos/child.git

git -C repos/child.git commit --allow-empty -qm initial

git -C parent remote add origin ../repos/super.git

git -C parent config branch.master.remote origin

git -C parent config branch.master.merge refs/heads/master

;;

root-anchor|root-single)

source=source

replacement=replacement

remote=../super.git

old=../../lib.git

if test "$scenario" = root-anchor; then

source=repos/source.git

replacement=repos/replacement.git

remote=../repos/super.git

old=../source.git

fi

git init -q -b master "$source"

git -C "$source" commit --allow-empty -qm initial

git clone -q "$source" "$replacement"

git -C parent remote add origin "$remote"

git -C parent submodule add "$root/$source" module

git -C parent config -f .gitmodules submodule.module.url "$old"

git -C parent add .gitmodules module

git -C parent commit -qm 'Record historical URL'

git -C parent rev-parse HEAD >previous

url="$root/$replacement"

if test "$scenario" = root-anchor; then url=../replacement.git; fi

git -C parent config -f .gitmodules submodule.module.url "$url"

git -C parent add .gitmodules

git -C parent commit -qm 'Change URL'

printf '%s' "$replacement" >replacement-path

;;

root-matches)

git init -q -b master source

git -C source commit --allow-empty -qm initial

git -C parent submodule add "$root/source" module

git -C parent config -f .gitmodules submodule.module.url ../source

git -C parent add .gitmodules module

git -C parent commit -qm 'Record relative URL'

git -C parent rev-parse HEAD >previous

git -C parent config -f .gitmodules submodule.module.url "$root/source"

git -C parent add .gitmodules

git -C parent commit -qm 'Use existing remote URL'

;;

update-remote)

git -C parent remote add origin ssh://git@host/org/super.git

mkdir parent/planted

;;

tracking-remote)

git -C parent commit --allow-empty -qm initial

git -C parent remote add origin git@host:other/super.git

;;