#!/bin/sh

USAGE='[start|bad|good|next|reset|visualize|replay|log|run]'
LONG_USAGE='git bisect start [<bad> [<good>...]] [--] [<pathspec>...]
        reset bisect state and start bisection.
git bisect bad [<rev>]
        mark <rev> a known-bad revision.
git bisect good [<rev>...]
        mark <rev>... known-good revisions.
git bisect next
        find next bisection to test and check it out.
git bisect reset [<branch>]
        finish bisection search and go back to branch.
git bisect visualize
        show bisect status in gitk.
git bisect replay <logfile>
        replay bisection log.
git bisect log
        show bisect log.
git bisect run <cmd>...
        use <cmd>... to automatically bisect.'

. git-sh-setup
require_work_tree

sq() {
        @@PERL@@ -e '
                for (@ARGV) {
                        s/'\''/'\'\\\\\'\''/g;
                        print " '\''$_'\''";
                }
                print "\n";
        ' "$@"
}

bisect_autostart() {
        test -d "$GIT_DIR/refs/bisect" || {
                echo >&2 'You need to start by "git bisect start"'
                if test -t 0
                then
                        echo >&2 -n 'Do you want me to do it for you [Y/n]? '
                        read yesno
                        case "$yesno" in
                        [Nn]*)
                                exit ;;
                        esac
                        bisect_start
                else
                        exit 1
                fi
        }
}

bisect_start() {
        #
        # Verify HEAD. If we were bisecting before this, reset to the
        # top-of-line master first!
        #
        head=$(GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD) ||
        die "Bad HEAD - I need a symbolic ref"
        case "$head" in
        refs/heads/bisect)
                if [ -s "$GIT_DIR/head-name" ]; then
                    branch=`cat "$GIT_DIR/head-name"`
                else
                    branch=master
                fi
                git checkout $branch || exit
                ;;
        refs/heads/*)
                [ -s "$GIT_DIR/head-name" ] && die "won't bisect on seeked tree"
                echo "$head" | sed 's#^refs/heads/##' >"$GIT_DIR/head-name"
                ;;
        *)
                die "Bad HEAD - strange symbolic ref"
                ;;
        esac

        #
        # Get rid of any old bisect state
        #
        bisect_clean_state
        mkdir "$GIT_DIR/refs/bisect"

        #
        # Check for one bad and then some good revisions.
        #
        has_double_dash=0
        for arg; do
            case "$arg" in --) has_double_dash=1; break ;; esac
        done
        orig_args=$(sq "$@")
        bad_seen=0
        while [ $# -gt 0 ]; do
            arg="$1"
            case "$arg" in
            --)
                shift
                break
                ;;
            *)
                rev=$(git-rev-parse --verify "$arg^{commit}" 2>/dev/null) || {
                    test $has_double_dash -eq 1 &&
                        die "'$arg' does not appear to be a valid revision"
                    break
                }
                if [ $bad_seen -eq 0 ]; then
                    bad_seen=1
                    bisect_write_bad "$rev"
                else
                    bisect_write_good "$rev"
                fi
                shift
                ;;
            esac
        done

        sq "$@" >"$GIT_DIR/BISECT_NAMES"
        {
            printf "git-bisect start"
            echo "$orig_args"
        } >>"$GIT_DIR/BISECT_LOG"
        bisect_auto_next
}

bisect_bad() {
        bisect_autostart
        case "$#" in
        0)
                rev=$(git-rev-parse --verify HEAD) ;;
        1)
                rev=$(git-rev-parse --verify "$1^{commit}") ;;
        *)
                usage ;;
        esac || exit
        bisect_write_bad "$rev"
        echo "git-bisect bad $rev" >>"$GIT_DIR/BISECT_LOG"
        bisect_auto_next
}

bisect_write_bad() {
        rev="$1"
        echo "$rev" >"$GIT_DIR/refs/bisect/bad"
        echo "# bad: "$(git-show-branch $rev) >>"$GIT_DIR/BISECT_LOG"
}

bisect_good() {
        bisect_autostart
        case "$#" in
        0)    revs=$(git-rev-parse --verify HEAD) || exit ;;
        *)    revs=$(git-rev-parse --revs-only --no-flags "$@") &&
                test '' != "$revs" || die "Bad rev input: $@" ;;
        esac
        for rev in $revs
        do
                rev=$(git-rev-parse --verify "$rev^{commit}") || exit
                bisect_write_good "$rev"
                echo "git-bisect good $rev" >>"$GIT_DIR/BISECT_LOG"

        done
        bisect_auto_next
}

bisect_write_good() {
        rev="$1"
        echo "$rev" >"$GIT_DIR/refs/bisect/good-$rev"
        echo "# good: "$(git-show-branch $rev) >>"$GIT_DIR/BISECT_LOG"
}

bisect_next_check() {
        next_ok=no
        git show-ref -q --verify refs/bisect/bad &&
        test -n "$(git for-each-ref "refs/bisect/good-*")" &&
        next_ok=yes

        case "$next_ok,$1" in
        no,) false ;;
        no,fail)
            THEN=''
            test -d "$GIT_DIR/refs/bisect" || {
                echo >&2 'You need to start by "git bisect start".'
                THEN='then '
            }
            echo >&2 'You '$THEN'need to give me at least one good' \
                'and one bad revisions.'
            echo >&2 '(You can use "git bisect bad" and' \
                '"git bisect good" for that.)'
            exit 1 ;;
        *)
            true ;;
        esac
}

bisect_auto_next() {
        bisect_next_check && bisect_next || :
}

bisect_next() {
        case "$#" in 0) ;; *) usage ;; esac
        bisect_autostart
        bisect_next_check fail
        bad=$(git-rev-parse --verify refs/bisect/bad) &&
        good=$(git-rev-parse --sq --revs-only --not \
                $(cd "$GIT_DIR" && ls refs/bisect/good-*)) &&
        rev=$(eval "git-rev-list --bisect $good $bad -- $(cat "$GIT_DIR/BISECT_NAMES")") || exit
        if [ -z "$rev" ]; then
            echo "$bad was both good and bad"
            exit 1
        fi
        if [ "$rev" = "$bad" ]; then
            echo "$rev is first bad commit"
            git-diff-tree --pretty $rev
            exit 0
        fi
        nr=$(eval "git-rev-list $rev $good -- $(cat $GIT_DIR/BISECT_NAMES)" | wc -l) || exit
        echo "Bisecting: $nr revisions left to test after this"
        echo "$rev" > "$GIT_DIR/refs/heads/new-bisect"
        git checkout -q new-bisect || exit
        mv "$GIT_DIR/refs/heads/new-bisect" "$GIT_DIR/refs/heads/bisect" &&
        GIT_DIR="$GIT_DIR" git-symbolic-ref HEAD refs/heads/bisect
        git-show-branch "$rev"
}

bisect_visualize() {
        bisect_next_check fail
        not=`cd "$GIT_DIR/refs" && echo bisect/good-*`
        eval gitk bisect/bad --not $not -- $(cat "$GIT_DIR/BISECT_NAMES")
}

bisect_reset() {
        case "$#" in
        0) if [ -s "$GIT_DIR/head-name" ]; then
               branch=`cat "$GIT_DIR/head-name"`
           else
               branch=master
           fi ;;
        1) git-show-ref --verify --quiet -- "refs/heads/$1" || {
               echo >&2 "$1 does not seem to be a valid branch"
               exit 1
           }
           branch="$1" ;;
        *)
            usage ;;
        esac
        if git checkout "$branch"; then
                rm -f "$GIT_DIR/head-name"
                bisect_clean_state
        fi
}

bisect_clean_state() {
        rm -fr "$GIT_DIR/refs/bisect"
        rm -f "$GIT_DIR/refs/heads/bisect"
        rm -f "$GIT_DIR/BISECT_LOG"
        rm -f "$GIT_DIR/BISECT_NAMES"
        rm -f "$GIT_DIR/BISECT_RUN"
}

bisect_replay () {
        test -r "$1" || {
                echo >&2 "cannot read $1 for replaying"
                exit 1
        }
        bisect_reset
        while read bisect command rev
        do
                test "$bisect" = "git-bisect" || continue
                case "$command" in
                start)
                        cmd="bisect_start $rev"
                        eval "$cmd"
                        ;;
                good)
                        echo "$rev" >"$GIT_DIR/refs/bisect/good-$rev"
                        echo "# good: "$(git-show-branch $rev) >>"$GIT_DIR/BISECT_LOG"
                        echo "git-bisect good $rev" >>"$GIT_DIR/BISECT_LOG"
                        ;;
                bad)
                        echo "$rev" >"$GIT_DIR/refs/bisect/bad"
                        echo "# bad: "$(git-show-branch $rev) >>"$GIT_DIR/BISECT_LOG"
                        echo "git-bisect bad $rev" >>"$GIT_DIR/BISECT_LOG"
                        ;;
                *)
                        echo >&2 "?? what are you talking about?"
                        exit 1 ;;
                esac
        done <"$1"
        bisect_auto_next
}

bisect_run () {
    bisect_next_check fail

    while true
    do
      echo "running $@"
      "$@"
      res=$?

      # Check for really bad run error.
      if [ $res -lt 0 -o $res -ge 128 ]; then
          echo >&2 "bisect run failed:"
          echo >&2 "exit code $res from '$@' is < 0 or >= 128"
          exit $res
      fi

      # Use "bisect_good" or "bisect_bad"
      # depending on run success or failure.
      if [ $res -gt 0 ]; then
          next_bisect='bisect_bad'
      else
          next_bisect='bisect_good'
      fi

      # We have to use a subshell because bisect_good or
      # bisect_bad functions can exit.
      ( $next_bisect > "$GIT_DIR/BISECT_RUN" )
      res=$?

      cat "$GIT_DIR/BISECT_RUN"

      if [ $res -ne 0 ]; then
          echo >&2 "bisect run failed:"
          echo >&2 "$next_bisect exited with error code $res"
          exit $res
      fi

      if grep "is first bad commit" "$GIT_DIR/BISECT_RUN" > /dev/null; then
          echo "bisect run success"
          exit 0;
      fi

    done
}


case "$#" in
0)
    usage ;;
*)
    cmd="$1"
    shift
    case "$cmd" in
    start)
        bisect_start "$@" ;;
    bad)
        bisect_bad "$@" ;;
    good)
        bisect_good "$@" ;;
    next)
        # Not sure we want "next" at the UI level anymore.
        bisect_next "$@" ;;
    visualize)
        bisect_visualize "$@" ;;
    reset)
        bisect_reset "$@" ;;
    replay)
        bisect_replay "$@" ;;
    log)
        cat "$GIT_DIR/BISECT_LOG" ;;
    run)
        bisect_run "$@" ;;
    *)
        usage ;;
    esac
esac