#!/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] [-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
}

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

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

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

cleanup_temp_files () {
    if test "$1" = --save-backup ; then
        mv -- "$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")'"
    else
        if base_present; then
            echo "modified"
        else
            echo "created"
        fi
    fi
}


resolve_symlink_merge () {
    while true; do
        printf "Use (l)ocal or (r)emote, or (a)bort? "
        read ans
        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
        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
}

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

    if test $? -eq 0 -a -n "$tmpfile" ; then
        mv -- "$(git rev-parse --show-cdup)$tmpfile" "$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"

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

    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;}')

    base_present   && checkout_staged_file 1 "$MERGED" "$BASE"
    local_present  && checkout_staged_file 2 "$MERGED" "$LOCAL"
    remote_present && checkout_staged_file 3 "$MERGED" "$REMOTE"

    if test -z "$local_mode" -o -z "$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" "$REMOTE"
    if "$prompt" = true; then
        printf "Hit return to start merge resolution tool (%s): " "$merge_tool"
        read ans
    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 || echo true)

while test $# != 0
do
    case "$1" in
        -t|--tool*)
            case "$#,$1" in
                *,*=*)
                    merge_tool=$(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
        case "$ans" in

            [yY]*)
                return 0
                ;;

            [nN]*)
                return 1
                ;;
        esac
    done
}

if test -z "$merge_tool"; then
    merge_tool=$(get_merge_tool "$merge_tool") || exit
fi
merge_keep_backup="$(git config --bool mergetool.keepBackup || echo true)"
merge_keep_temporaries="$(git config --bool mergetool.keepTemporaries || echo false)"

last_status=0
rollup_status=0
rerere=false

files_to_merge() {
    if test "$rerere" = true
    then
        git rerere status
    else
        git ls-files -u | sed -e 's/^[^ ]*      //' | sort -u
    fi
}


if test $# -eq 0 ; then
    cd_to_toplevel

    if test -e "$GIT_DIR/MERGE_RR"
    then
        rerere=true
    fi

    files=$(files_to_merge)
    if test -z "$files" ; then
        echo "No files need merging"
        exit 0
    fi

    # Save original stdin
    exec 3<&0

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

    files_to_merge |
    while IFS= read i
    do
        if test $last_status -ne 0; then
            prompt_after_failed_merge <&3 || exit 1
        fi
        printf "\n"
        merge_file "$i" <&3
        last_status=$?
        if test $last_status -ne 0; then
            rollup_status=1
        fi
    done
else
    while test $# -gt 0; do
        if test $last_status -ne 0; then
            prompt_after_failed_merge || exit 1
        fi
        printf "\n"
        merge_file "$1"
        last_status=$?
        if test $last_status -ne 0; then
            rollup_status=1
        fi
        shift
    done
fi

exit $rollup_status