#!/bin/sh
# Copyright (C) 2005 Junio C Hamano
#
# Applying diff between two trees to the work tree can be
# done with the following single command:
#
# GIT_EXTERNAL_DIFF=git-apply-patch-script git-diff-tree -p $tree1 $tree2
#

case "$#" in
1)
    echo >&2 "cannot handle unmerged diff on path $1."
    exit 1 ;;
esac
name="$1" tmp1="$2" hex1="$3" mode1="$4" tmp2="$5" hex2="$6" mode2="$7"

type1=f
case "$mode1" in
*120???) type1=l  ;;
*1007??) mode1=+x ;;
*1006??) mode1=-x ;;
.)       type1=-  ;; 
esac

type2=f
case "$mode2" in
*120???) type2=l  ;;
*1007??) mode2=+x ;;
*1006??) mode2=-x ;;
.)       type2=-  ;; 
esac

case "$type1,$type2" in

-,?)
    dir=$(dirname "$name")
    case "$dir" in '' | .) ;; *) mkdir -p "$dir" ;; esac || {
	echo >&2 "cannot create leading path for $name."
	exit 1
    }
    if test -e "$name"
    then
	echo >&2 "path $name to be created already exists."
	exit 1
    fi
    case "$type2" in
    f)
        # creating a regular file
	cat "$tmp2" >"$name" || {
	    echo >&2 "cannot create a regular file $name."
	    exit 1
	} 
	case "$mode2" in
	+x)
	    echo >&2 "created a regular file $name with mode +x."
	    chmod "$mode2" "$name"
	    ;;
	-x)
	    echo >&2 "created a regular file $name."
            ;;
        esac
	;;
    l)
        # creating a symlink
        ln -s "$(cat "$tmp2")" "$name" || {
	    echo >&2 "cannot create a symbolic link $name."
	    exit 1
	}
	echo >&2 "created a symbolic link $name."
        ;;
    *)
        echo >&2 "do not know how to create $name of type $type2."
	exit 1
    esac
    git-update-cache --add -- "$name" ;;

?,-)
    rm -f "$name" || {
	echo >&2 "cannot remove $name"
	exit 1
    }
    echo >&2 "deleted $name."
    git-update-cache --remove -- "$name" ;;

l,f|f,l)
    echo >&2 "cannot change a regular file $name and a symbolic link $name."
    exit 1 ;;

l,l)
    # symlink to symlink
    current=$(readlink "$name") || {
	echo >&2 "cannot read the target of the symbolic link $name."
	exit 1
    }
    original=$(cat "$tmp1")
    next=$(cat "$tmp2")
    test "$original" != "$current" || {
	echo >&2 "cannot apply symbolic link target change ($original->$next) to $name which points to $current."
	exit 1
    }
    if test "$next" != "$current"
    then
	rm -f "$name" && ln -s "$next" "$name" || {
	    echo >&2 "cannot create symbolic link $name."
	    exit 1
	}
	echo >&2 "changed symbolic target of $name."
        git-update-cache -- "$name"
    fi ;;

f,f)
    # changed
    test -e "$name" || {
	echo >&2 "regular file $name to be patched does not exist."
	exit 1
    }
    dir=$(dirname "$name")
    case "$dir" in '' | .) ;; *) mkdir -p "$dir";; esac || {
	echo >&2 "cannot create leading path for $name."
	exit 1
    }
    tmp=.git-apply-patch-$$
    trap "rm -f $tmp-*" 0 1 2 3 15

    # Be careful, in case "$tmp2" is borrowed path from the work tree
    # we are looking at...
    diff -u -L "a/$name" -L "b/$name" "$tmp1" "$tmp2" >$tmp-patch

    # This will say "patching ..." so we do not say anything outselves.
    patch -p1 <$tmp-patch || exit
    rm -f $tmp-patch
    case "$mode1,$mode2" in
    "$mode2,$mode1") ;;
    *)
	chmod "$mode2" "$name"
	echo >&2 "changed mode from $mode1 to $mode2."
	;;
    esac
    git-update-cache -- "$name"

esac