#!/bin/sh
#
# This program resolves merge conflicts in git
#
# Copyright (c) 2006 Theodore Y. Ts'o
#
# This file is licensed under the GPL v2, or a later version
# at the discretion of Junio C Hamano.
#

USAGE='[--tool=tool] [--tool-help] [-y|--no-prompt|--prompt] [file to merge] ...'
SUBDIRECTORY_OK=Yes
OPTIONS_SPEC=
TOOL_MODE=merge
. git-sh-setup
. git-mergetool--lib
require_work_tree

# Returns true if the mode reflects a symlink
is_symlink () {
	test "$1" = 120000
}

is_submodule () {
	test "$1" = 160000
}

local_present () {
	test -n "$local_mode"
}

remote_present () {
	test -n "$remote_mode"
}

base_present () {
	test -n "$base_mode"
}

cleanup_temp_files () {
	if test "$1" = --save-backup
	then
		rm -rf -- "$MERGED.orig"
		test -e "$BACKUP" && mv -- "$BACKUP" "$MERGED.orig"
		rm -f -- "$LOCAL" "$REMOTE" "$BASE"
	else
		rm -f -- "$LOCAL" "$REMOTE" "$BASE" "$BACKUP"
	fi
}

describe_file () {
	mode="$1"
	branch="$2"
	file="$3"

	printf "  {%s}: " "$branch"
	if test -z "$mode"
	then
		echo "deleted"
	elif is_symlink "$mode"
	then
		echo "a symbolic link -> '$(cat "$file")'"
	elif is_submodule "$mode"
	then
		echo "submodule commit $file"
	elif base_present
	then
		echo "modified file"
	else
		echo "created file"
	fi
}

resolve_symlink_merge () {
	while true
	do
		printf "Use (l)ocal or (r)emote, or (a)bort? "
		read ans || return 1
		case "$ans" in
		[lL]*)
			git checkout-index -f --stage=2 -- "$MERGED"
			git add -- "$MERGED"
			cleanup_temp_files --save-backup
			return 0
			;;
		[rR]*)
			git checkout-index -f --stage=3 -- "$MERGED"
			git add -- "$MERGED"
			cleanup_temp_files --save-backup
			return 0
			;;
		[aA]*)
			return 1
			;;
		esac
	done
}

resolve_deleted_merge () {
	while true
	do
		if base_present
		then
			printf "Use (m)odified or (d)eleted file, or (a)bort? "
		else
			printf "Use (c)reated or (d)eleted file, or (a)bort? "
		fi
		read ans || return 1
		case "$ans" in
		[mMcC]*)
			git add -- "$MERGED"
			cleanup_temp_files --save-backup
			return 0
			;;
		[dD]*)
			git rm -- "$MERGED" > /dev/null
			cleanup_temp_files
			return 0
			;;
		[aA]*)
			return 1
			;;
		esac
	done
}

resolve_submodule_merge () {
	while true
	do
		printf "Use (l)ocal or (r)emote, or (a)bort? "
		read ans || return 1
		case "$ans" in
		[lL]*)
			if ! local_present
			then
				if test -n "$(git ls-tree HEAD -- "$MERGED")"
				then
					# Local isn't present, but it's a subdirectory
					git ls-tree --full-name -r HEAD -- "$MERGED" |
					git update-index --index-info || exit $?
				else
					test -e "$MERGED" && mv -- "$MERGED" "$BACKUP"
					git update-index --force-remove "$MERGED"
					cleanup_temp_files --save-backup
				fi
			elif is_submodule "$local_mode"
			then
				stage_submodule "$MERGED" "$local_sha1"
			else
				git checkout-index -f --stage=2 -- "$MERGED"
				git add -- "$MERGED"
			fi
			return 0
			;;
		[rR]*)
			if ! remote_present
			then
				if test -n "$(git ls-tree MERGE_HEAD -- "$MERGED")"
				then
					# Remote isn't present, but it's a subdirectory
					git ls-tree --full-name -r MERGE_HEAD -- "$MERGED" |
					git update-index --index-info || exit $?
				else
					test -e "$MERGED" && mv -- "$MERGED" "$BACKUP"
					git update-index --force-remove "$MERGED"
				fi
			elif is_submodule "$remote_mode"
			then
				! is_submodule "$local_mode" &&
				test -e "$MERGED" &&
				mv -- "$MERGED" "$BACKUP"
				stage_submodule "$MERGED" "$remote_sha1"
			else
				test -e "$MERGED" && mv -- "$MERGED" "$BACKUP"
				git checkout-index -f --stage=3 -- "$MERGED"
				git add -- "$MERGED"
			fi
			cleanup_temp_files --save-backup
			return 0
			;;
		[aA]*)
			return 1
			;;
		esac
	done
}

stage_submodule () {
	path="$1"
	submodule_sha1="$2"
	mkdir -p "$path" ||
	die "fatal: unable to create directory for module at $path"
	# Find $path relative to work tree
	work_tree_root=$(cd_to_toplevel && pwd)
	work_rel_path=$(cd "$path" &&
		GIT_WORK_TREE="${work_tree_root}" git rev-parse --show-prefix
	)
	test -n "$work_rel_path" ||
	die "fatal: unable to get path of module $path relative to work tree"
	git update-index --add --replace --cacheinfo 160000 "$submodule_sha1" "${work_rel_path%/}" || die
}

checkout_staged_file () {
	tmpfile=$(expr \
		"$(git checkout-index --temp --stage="$1" "$2" 2>/dev/null)" \
		: '\([^	]*\)	')

	if test $? -eq 0 && test -n "$tmpfile"
	then
		mv -- "$(git rev-parse --show-cdup)$tmpfile" "$3"
	else
		>"$3"
	fi
}

merge_file () {
	MERGED="$1"

	f=$(git ls-files -u -- "$MERGED")
	if test -z "$f"
	then
		if test ! -f "$MERGED"
		then
			echo "$MERGED: file not found"
		else
			echo "$MERGED: file does not need merging"
		fi
		return 1
	fi

	ext="$$$(expr "$MERGED" : '.*\(\.[^/]*\)$')"
	BACKUP="./$MERGED.BACKUP.$ext"
	LOCAL="./$MERGED.LOCAL.$ext"
	REMOTE="./$MERGED.REMOTE.$ext"
	BASE="./$MERGED.BASE.$ext"

	base_mode=$(git ls-files -u -- "$MERGED" | awk '{if ($3==1) print $1;}')
	local_mode=$(git ls-files -u -- "$MERGED" | awk '{if ($3==2) print $1;}')
	remote_mode=$(git ls-files -u -- "$MERGED" | awk '{if ($3==3) print $1;}')

	if is_submodule "$local_mode" || is_submodule "$remote_mode"
	then
		echo "Submodule merge conflict for '$MERGED':"
		local_sha1=$(git ls-files -u -- "$MERGED" | awk '{if ($3==2) print $2;}')
		remote_sha1=$(git ls-files -u -- "$MERGED" | awk '{if ($3==3) print $2;}')
		describe_file "$local_mode" "local" "$local_sha1"
		describe_file "$remote_mode" "remote" "$remote_sha1"
		resolve_submodule_merge
		return
	fi

	mv -- "$MERGED" "$BACKUP"
	cp -- "$BACKUP" "$MERGED"

	checkout_staged_file 1 "$MERGED" "$BASE"
	checkout_staged_file 2 "$MERGED" "$LOCAL"
	checkout_staged_file 3 "$MERGED" "$REMOTE"

	if test -z "$local_mode" || test -z "$remote_mode"
	then
		echo "Deleted merge conflict for '$MERGED':"
		describe_file "$local_mode" "local" "$LOCAL"
		describe_file "$remote_mode" "remote" "$REMOTE"
		resolve_deleted_merge
		return
	fi

	if is_symlink "$local_mode" || is_symlink "$remote_mode"
	then
		echo "Symbolic link merge conflict for '$MERGED':"
		describe_file "$local_mode" "local" "$LOCAL"
		describe_file "$remote_mode" "remote" "$REMOTE"
		resolve_symlink_merge
		return
	fi

	echo "Normal merge conflict for '$MERGED':"
	describe_file "$local_mode" "local" "$LOCAL"
	describe_file "$remote_mode" "remote" "$REMOTE"
	if test "$guessed_merge_tool" = true || test "$prompt" = true
	then
		printf "Hit return to start merge resolution tool (%s): " "$merge_tool"
		read ans || return 1
	fi

	if base_present
	then
		present=true
	else
		present=false
	fi

	if ! run_merge_tool "$merge_tool" "$present"
	then
		echo "merge of $MERGED failed" 1>&2
		mv -- "$BACKUP" "$MERGED"

		if test "$merge_keep_temporaries" = "false"
		then
			cleanup_temp_files
		fi

		return 1
	fi

	if test "$merge_keep_backup" = "true"
	then
		mv -- "$BACKUP" "$MERGED.orig"
	else
		rm -- "$BACKUP"
	fi

	git add -- "$MERGED"
	cleanup_temp_files
	return 0
}

prompt=$(git config --bool mergetool.prompt)
guessed_merge_tool=false

while test $# != 0
do
	case "$1" in
	--tool-help)
		show_tool_help
		;;
	-t|--tool*)
		case "$#,$1" in
		*,*=*)
			merge_tool=$(expr "z$1" : 'z-[^=]*=\(.*\)')
			;;
		1,*)
			usage ;;
		*)
			merge_tool="$2"
			shift ;;
		esac
		;;
	-y|--no-prompt)
		prompt=false
		;;
	--prompt)
		prompt=true
		;;
	--)
		shift
		break
		;;
	-*)
		usage
		;;
	*)
		break
		;;
	esac
	shift
done

prompt_after_failed_merge () {
	while true
	do
		printf "Continue merging other unresolved paths (y/n) ? "
		read ans || return 1
		case "$ans" in
		[yY]*)
			return 0
			;;
		[nN]*)
			return 1
			;;
		esac
	done
}

if test -z "$merge_tool"
then
	# Check if a merge tool has been configured
	merge_tool=$(get_configured_merge_tool)
	# Try to guess an appropriate merge tool if no tool has been set.
	if test -z "$merge_tool"
	then
		merge_tool=$(guess_merge_tool) || exit
		guessed_merge_tool=true
	fi
fi
merge_keep_backup="$(git config --bool mergetool.keepBackup || echo true)"
merge_keep_temporaries="$(git config --bool mergetool.keepTemporaries || echo false)"

last_status=0
rollup_status=0
files=

if test $# -eq 0
then
	cd_to_toplevel

	if test -e "$GIT_DIR/MERGE_RR"
	then
		files=$(git rerere remaining)
	else
		files=$(git ls-files -u | sed -e 's/^[^	]*	//' | sort -u)
	fi
else
	files=$(git ls-files -u -- "$@" | sed -e 's/^[^	]*	//' | sort -u)
fi

if test -z "$files"
then
	echo "No files need merging"
	exit 0
fi

printf "Merging:\n"
printf "%s\n" "$files"

IFS='
'
for i in $files
do
	if test $last_status -ne 0
	then
		prompt_after_failed_merge || exit 1
	fi
	printf "\n"
	merge_file "$i"
	last_status=$?
	if test $last_status -ne 0
	then
		rollup_status=1
	fi
done

exit $rollup_status