#!/bin/sh

USAGE='[start|bad|good|skip|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 skip [<rev>...]
        mark <rev>... untestable 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 "${head#refs/heads/}" >"$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
                }
                case $bad_seen in
                0) state='bad' ; bad_seen=1 ;;
                *) state='good' ;;
                esac
                bisect_write "$state" "$rev" 'nolog'
                shift
                ;;
            esac
        done

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

bisect_write() {
        state="$1"
        rev="$2"
        nolog="$3"
        case "$state" in
                bad)            tag="$state" ;;
                good|skip)      tag="$state"-"$rev" ;;
                *)              die "Bad bisect_write argument: $state" ;;
        esac
        git update-ref "refs/bisect/$tag" "$rev"
        echo "# $state: "$(git show-branch $rev) >>"$GIT_DIR/BISECT_LOG"
        test -z "$nolog" && echo "git-bisect $state $rev" >>"$GIT_DIR/BISECT_LOG"
}

bisect_state() {
        bisect_autostart
        state=$1
        case "$#,$state" in
        0,*)
                die "Please call 'bisect_state' with at least one argument." ;;
        1,bad|1,good|1,skip)
                rev=$(git rev-parse --verify HEAD) ||
                        die "Bad rev input: HEAD"
                bisect_write "$state" "$rev" ;;
        2,bad)
                rev=$(git rev-parse --verify "$2^{commit}") ||
                        die "Bad rev input: $2"
                bisect_write "$state" "$rev" ;;
        *,good|*,skip)
                shift
                revs=$(git rev-parse --revs-only --no-flags "$@") &&
                        test '' != "$revs" || die "Bad rev input: $@"
                for rev in $revs
                do
                        rev=$(git rev-parse --verify "$rev^{commit}") ||
                                die "Bad rev commit: $rev^{commit}"
                        bisect_write "$state" "$rev"
                done ;;
        *)
                usage ;;
        esac
        bisect_auto_next
}

bisect_next_check() {
        missing_good= missing_bad=
        git show-ref -q --verify refs/bisect/bad || missing_bad=t
        test -n "$(git for-each-ref "refs/bisect/good-*")" || missing_good=t

        case "$missing_good,$missing_bad,$1" in
        ,,*)
                : have both good and bad - ok
                ;;
        *,)
                # do not have both but not asked to fail - just report.
                false
                ;;
        t,,good)
                # have bad but not good.  we could bisect although
                # this is less optimum.
                echo >&2 'Warning: bisecting only with a bad commit.'
                if test -t 0
                then
                        printf >&2 'Are you sure [Y/n]? '
                        case "$(read yesno)" in [Nn]*) exit 1 ;; esac
                fi
                : bisect without good...
                ;;
        *)
                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 ;;
        esac
}

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

filter_skipped() {
        _eval="$1"
        _skip="$2"

        if [ -z "$_skip" ]; then
                eval $_eval
                return
        fi

        # Let's parse the output of:
        # "git rev-list --bisect-vars --bisect-all ..."
        eval $_eval | while read hash line
        do
                case "$VARS,$FOUND,$TRIED,$hash" in
                        # We display some vars.
                        1,*,*,*) echo "$hash $line" ;;

                        # Split line.
                        ,*,*,---*) ;;

                        # We had nothing to search.
                        ,,,bisect_rev*)
                                echo "bisect_rev="
                                VARS=1
                                ;;

                        # We did not find a good bisect rev.
                        # This should happen only if the "bad"
                        # commit is also a "skip" commit.
                        ,,*,bisect_rev*)
                                echo "bisect_rev=$TRIED"
                                VARS=1
                                ;;

                        # We are searching.
                        ,,*,*)
                                TRIED="${TRIED:+$TRIED|}$hash"
                                case "$_skip" in
                                *$hash*) ;;
                                *)
                                        echo "bisect_rev=$hash"
                                        echo "bisect_tried=\"$TRIED\""
                                        FOUND=1
                                        ;;
                                esac
                                ;;

                        # We have already found a rev to be tested.
                        ,1,*,bisect_rev*) VARS=1 ;;
                        ,1,*,*) ;;

                        # ???
                        *) die "filter_skipped error " \
                            "VARS: '$VARS' " \
                            "FOUND: '$FOUND' " \
                            "TRIED: '$TRIED' " \
                            "hash: '$hash' " \
                            "line: '$line'"
                        ;;
                esac
        done
}

exit_if_skipped_commits () {
        _tried=$1
        if expr "$_tried" : ".*[|].*" > /dev/null ; then
                echo "There are only 'skip'ped commit left to test."
                echo "The first bad commit could be any of:"
                echo "$_tried" | tr '[|]' '[\012]'
                echo "We cannot bisect more!"
                exit 2
        fi
}

bisect_next() {
        case "$#" in 0) ;; *) usage ;; esac
        bisect_autostart
        bisect_next_check good

        skip=$(git for-each-ref --format='%(objectname)' \
                "refs/bisect/skip-*" | tr '[\012]' ' ') || exit

        BISECT_OPT=''
        test -n "$skip" && BISECT_OPT='--bisect-all'

        bad=$(git rev-parse --verify refs/bisect/bad) &&
        good=$(git for-each-ref --format='^%(objectname)' \
                "refs/bisect/good-*" | tr '[\012]' ' ') &&
        eval="git rev-list --bisect-vars $BISECT_OPT $good $bad --" &&
        eval="$eval $(cat "$GIT_DIR/BISECT_NAMES")" &&
        eval=$(filter_skipped "$eval" "$skip") &&
        eval "$eval" || exit

        if [ -z "$bisect_rev" ]; then
                echo "$bad was both good and bad"
                exit 1
        fi
        if [ "$bisect_rev" = "$bad" ]; then
                exit_if_skipped_commits "$bisect_tried"
                echo "$bisect_rev is first bad commit"
                git diff-tree --pretty $bisect_rev
                exit 0
        fi

        # We should exit here only if the "bad"
        # commit is also a "skip" commit (see above).
        exit_if_skipped_commits "$bisect_rev"

        echo "Bisecting: $bisect_nr revisions left to test after this"
        echo "$bisect_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 "$bisect_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" ||
               die "$1 does not seem to be a valid branch"
           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"

        # There may be some refs packed during bisection.
        git for-each-ref --format='%(refname) %(objectname)' refs/bisect/\* refs/heads/bisect |
        while read ref hash
        do
                git update-ref -d $ref $hash
        done
        rm -f "$GIT_DIR/BISECT_LOG"
        rm -f "$GIT_DIR/BISECT_NAMES"
        rm -f "$GIT_DIR/BISECT_RUN"
}

bisect_replay () {
        test -r "$1" || die "cannot read $1 for replaying"
        bisect_reset
        while read bisect command rev
        do
                test "$bisect" = "git-bisect" || continue
                case "$command" in
                start)
                        cmd="bisect_start $rev"
                        eval "$cmd" ;;
                good|bad|skip)
                        bisect_write "$command" "$rev" ;;
                *)
                        die "?? what are you talking about?" ;;
                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

      # Find current state depending on run success or failure.
      # A special exit code of 125 means cannot test.
      if [ $res -eq 125 ]; then
          state='skip'
      elif [ $res -gt 0 ]; then
          state='bad'
      else
          state='good'
      fi

      # We have to use a subshell because "bisect_state" can exit.
      ( bisect_state $state > "$GIT_DIR/BISECT_RUN" )
      res=$?

      cat "$GIT_DIR/BISECT_RUN"

      if grep "first bad commit could be any of" "$GIT_DIR/BISECT_RUN" \
                > /dev/null; then
          echo >&2 "bisect run cannot continue any more"
          exit $res
      fi

      if [ $res -ne 0 ]; then
          echo >&2 "bisect run failed:"
          echo >&2 "'bisect_state $state' 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 "$@" ;;
    bad|good|skip)
        bisect_state "$cmd" "$@" ;;
    next)
        # Not sure we want "next" at the UI level anymore.
        bisect_next "$@" ;;
    visualize)
        bisect_visualize "$@" ;;
    reset)
        bisect_reset "$@" ;;
    replay)
        bisect_replay "$@" ;;
    log)
        cat "$GIT_DIR/BISECT_LOG" ;;
    run)
        bisect_run "$@" ;;
    *)
        usage ;;
    esac
esac