#!/bin/bash

abort() {
	echo $1
	exit 1
}

cmd="$1"
shift

USAGE="usage: zit COMMAND FILE [ARGS...]"

zit_help() {
	cmd="$1"
	shift
	case $cmd in
		git)
		git help "$@"
		;;
		*)
		echo $USAGE
		echo ""
		echo "Set up a git repository under .zit.FILE to track changes for FILE."
		echo "File must be a regular file and in the current directory."
		echo "The filesystem must support hardlinks."
		echo ""
		echo "Zit commands:"
		echo "   init		Synonym for track"
		echo "   list		Synonym for tracked"
		echo "   track	Start tracking changes to FILE"
		echo "   tracked	List tracked files in current directory"
		echo ""
		echo "See 'zit help git' or 'git help' for git commands."
		;;
	esac
}

zit_setup() {
	ZIT_FILE="$1"
	test $ZIT_FILE || abort "Please specify a file"
	shift
	test -f $ZIT_FILE || abort "No such file $ZIT_FILE"
	test $ZIT_FILE = "`basename $ZIT_FILE`" || abort "Sorry, Zit only works on files in the current directory"
	ZIT_DIR=".zit.$ZIT_FILE"
}

zit_init() {
	zit_setup $1
	test -e $ZIT_DIR && abort "$ZIT_DIR exists, is $ZIT_FILE tracked already?"
	mkdir $ZIT_DIR && echo "Initializing Zit repository in $ZIT_DIR"
	test -d $ZIT_DIR || abort "Failed to create $ZIT_DIR"
	cd $ZIT_DIR
	git init || abort "Failed to initialize Git repository in $ZIT_DIR" 
	ln ../$ZIT_FILE $ZIT_FILE || abort "Failed to link $ZIT_FILE into $ZIT_DIR"
	git add $ZIT_FILE || abort "Failed to add $ZIT_FILE"
	git commit "$@" || abort "Failed to make first commit for $ZIT_FILE"
}

zit_list() {
	for file in `find -path ./.zit.\*/.git`; do
		export GIT_DIR="$file"
		file="${file#./.zit.}"
		file="${file%/.git}"
		# TODO show actual file status
		git ls-files -t $file
	done;
}

case $cmd in
	"")
	echo $USAGE
	;;
	help)
	zit_help "$@"
	;;
	init|track)
	zit_init $1
	;;
	list|tracked)
	zit_list
	;;
	*)
	zit_setup $1
	cd $ZIT_DIR
	git $cmd "$@" $1
	;;
esac