#!/bin/sh

USAGE='[help|start|bad|good|skip|next|reset|visualize|replay|log|run]'
LONG_USAGE='git bisect help
        print this long help message.
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>|<range>)...]
        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.

Please use "git help bisect" to get the full man page.'

OPTIONS_SPEC=
. git-sh-setup
require_work_tree

_x40='[0-9a-f][0-9a-f][0-9a-f][0-9a-f][0-9a-f]'
_x40="$_x40$_x40$_x40$_x40$_x40$_x40$_x40$_x40"

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

bisect_start() {
        #
        # Verify HEAD.
        #
        head=$(GIT_DIR="$GIT_DIR" git symbolic-ref -q HEAD) ||
        head=$(GIT_DIR="$GIT_DIR" git rev-parse --verify HEAD) ||
        die "Bad HEAD - I need a HEAD"

        #
        # Check if we are bisecting.
        #
        start_head=''
        if test -s "$GIT_DIR/BISECT_START"
        then
                # Reset to the rev from where we started.
                start_head=$(cat "$GIT_DIR/BISECT_START")
                git checkout "$start_head" -- || exit
        else
                # Get rev from where we start.
                case "$head" in
                refs/heads/*|$_x40)
                        # This error message should only be triggered by
                        # cogito usage, and cogito users should understand
                        # it relates to cg-seek.
                        [ -s "$GIT_DIR/head-name" ] &&
                                die "won't bisect on seeked tree"
                        start_head="${head#refs/heads/}"
                        ;;
                *)
                        die "Bad HEAD - strange symbolic ref"
                        ;;
                esac
        fi

        #
        # Get rid of any old bisect state.
        #
        bisect_clean_state || exit

        #
        # Check for one bad and then some good revisions.
        #
        has_double_dash=0
        for arg; do
            case "$arg" in --) has_double_dash=1; break ;; esac
        done
        orig_args=$(git rev-parse --sq-quote "$@")
        bad_seen=0
        eval=''
        while [ $# -gt 0 ]; do
            arg="$1"
            case "$arg" in
            --)
                shift
                break
                ;;
            *)
                rev=$(git rev-parse -q --verify "$arg^{commit}") || {
                    test $has_double_dash -eq 1 &&
                        die "'$arg' does not appear to be a valid revision"
                    break
                }
                case $bad_seen in
                0) state='bad' ; bad_seen=1 ;;
                *) state='good' ;;
                esac
                eval="$eval bisect_write '$state' '$rev' 'nolog'; "
                shift
                ;;
            esac
        done

        #
        # Change state.
        # In case of mistaken revs or checkout error, or signals received,
        # "bisect_auto_next" below may exit or misbehave.
        # We have to trap this to be able to clean up using
        # "bisect_clean_state".
        #
        trap 'bisect_clean_state' 0
        trap 'exit 255' 1 2 3 15

        #
        # Write new start state.
        #
        echo "$start_head" >"$GIT_DIR/BISECT_START" &&
        git rev-parse --sq-quote "$@" >"$GIT_DIR/BISECT_NAMES" &&
        eval "$eval" &&
        echo "git bisect start$orig_args" >>"$GIT_DIR/BISECT_LOG" || exit
        #
        # Check if we can proceed to the next bisect state.
        #
        bisect_auto_next

        trap '-' 0
}

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" || exit
        echo "# $state: $(git show-branch $rev)" >>"$GIT_DIR/BISECT_LOG"
        test -n "$nolog" || echo "git bisect $state $rev" >>"$GIT_DIR/BISECT_LOG"
}

is_expected_rev() {
        test -f "$GIT_DIR/BISECT_EXPECTED_REV" &&
        test "$1" = $(cat "$GIT_DIR/BISECT_EXPECTED_REV")
}

mark_expected_rev() {
        echo "$1" > "$GIT_DIR/BISECT_EXPECTED_REV"
}

check_expected_revs() {
        for _rev in "$@"; do
                if ! is_expected_rev "$_rev"; then
                        rm -f "$GIT_DIR/BISECT_ANCESTORS_OK"
                        rm -f "$GIT_DIR/BISECT_EXPECTED_REV"
                        return
                fi
        done
}

bisect_skip() {
        all=''
        for arg in "$@"
        do
            case "$arg" in
            *..*)
                revs=$(git rev-list "$arg") || die "Bad rev input: $arg" ;;
            *)
                revs=$(git rev-parse --sq-quote "$arg") ;;
            esac
            all="$all $revs"
        done
        eval bisect_state 'skip' $all
}

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"
                check_expected_revs "$rev" ;;
        2,bad|*,good|*,skip)
                shift
                eval=''
                for rev in "$@"
                do
                        sha=$(git rev-parse --verify "$rev^{commit}") ||
                                die "Bad rev input: $rev"
                        eval="$eval bisect_write '$state' '$sha'; "
                done
                eval "$eval"
                check_expected_revs "$@" ;;
        *,bad)
                die "'git bisect bad' can take only one argument." ;;
        *)
                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,$1" in
        ,,*)
                : have both good and bad - ok
                ;;
        *,)
                # do not have both but not asked to fail - just report.
                false
                ;;
        t,,good)
                # have bad but not good.  we could bisect although
                # this is less optimum.
                echo >&2 'Warning: bisecting only with a bad commit.'
                if test -t 0
                then
                        printf >&2 'Are you sure [Y/n]? '
                        read yesno
                        case "$yesno" in [Nn]*) exit 1 ;; esac
                fi
                : bisect without good...
                ;;
        *)
                THEN=''
                test -s "$GIT_DIR/BISECT_START" || {
                        echo >&2 'You need to start by "git bisect start".'
                        THEN='then '
                }
                echo >&2 'You '$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 || :
}

bisect_checkout() {
        _rev="$1"
        _msg="$2"
        echo "Bisecting: $_msg"
        mark_expected_rev "$_rev"
        git checkout -q "$_rev" -- || exit
        git show-branch "$_rev"
}

is_among() {
        _rev="$1"
        _list="$2"
        case "$_list" in *$_rev*) return 0 ;; esac
        return 1
}

handle_bad_merge_base() {
        _badmb="$1"
        _good="$2"
        if is_expected_rev "$_badmb"; then
                cat >&2 <<EOF
The merge base $_badmb is bad.
This means the bug has been fixed between $_badmb and [$_good].
EOF
                exit 3
        else
                cat >&2 <<EOF
Some good revs are not ancestor of the bad rev.
git bisect cannot work properly in this case.
Maybe you mistake good and bad revs?
EOF
                exit 1
        fi
}

handle_skipped_merge_base() {
        _mb="$1"
        _bad="$2"
        _good="$3"
        cat >&2 <<EOF
Warning: the merge base between $_bad and [$_good] must be skipped.
So we cannot be sure the first bad commit is between $_mb and $_bad.
We continue anyway.
EOF
}

#
# "check_merge_bases" checks that merge bases are not "bad".
#
# - If one is "good", that's good, we have nothing to do.
# - If one is "bad", it means the user assumed something wrong
# and we must exit.
# - If one is "skipped", we can't know but we should warn.
# - If we don't know, we should check it out and ask the user to test.
#
# In the last case we will return 1, and otherwise 0.
#
check_merge_bases() {
        _bad="$1"
        _good="$2"
        _skip="$3"
        for _mb in $(git merge-base --all $_bad $_good)
        do
                if is_among "$_mb" "$_good"; then
                        continue
                elif test "$_mb" = "$_bad"; then
                        handle_bad_merge_base "$_bad" "$_good"
                elif is_among "$_mb" "$_skip"; then
                        handle_skipped_merge_base "$_mb" "$_bad" "$_good"
                else
                        bisect_checkout "$_mb" "a merge base must be tested"
                        return 1
                fi
        done
        return 0
}

#
# "check_good_are_ancestors_of_bad" checks that all "good" revs are
# ancestor of the "bad" rev.
#
# If that's not the case, we need to check the merge bases.
# If a merge base must be tested by the user we return 1 and
# otherwise 0.
#
check_good_are_ancestors_of_bad() {
        test -f "$GIT_DIR/BISECT_ANCESTORS_OK" &&
                return

        _bad="$1"
        _good=$(echo $2 | sed -e 's/\^//g')
        _skip="$3"

        # Bisecting with no good rev is ok
        test -z "$_good" && return

        _side=$(git rev-list $_good ^$_bad)
        if test -n "$_side"; then
                # Return if a checkout was done
                check_merge_bases "$_bad" "$_good" "$_skip" || return
        fi

        : > "$GIT_DIR/BISECT_ANCESTORS_OK"

        return 0
}

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

        # Get bad, good and skipped revs
        bad=$(git rev-parse --verify refs/bisect/bad) &&
        good=$(git for-each-ref --format='^%(objectname)' \
                "refs/bisect/good-*" | tr '\012' ' ') &&
        skip=$(git for-each-ref --format='%(objectname)' \
                "refs/bisect/skip-*" | tr '\012' ' ') || exit

        # Maybe some merge bases must be tested first
        check_good_are_ancestors_of_bad "$bad" "$good" "$skip"
        # Return now if a checkout has already been done
        test "$?" -eq "1" && return

        # Perform bisection computation, display and checkout
        git bisect--helper --next-exit
        res=$?

        # Check if we should exit because bisection is finished
        test $res -eq 10 && exit 0

        # Check for an error in the bisection process
        test $res -ne 0 && exit $res

        return 0
}

bisect_visualize() {
        bisect_next_check fail

        if test $# = 0
        then
                case "${DISPLAY+set}${SESSIONNAME+set}${MSYSTEM+set}${SECURITYSESSIONID+set}" in
                '')     set git log ;;
                set*)   set gitk ;;
                esac
        else
                case "$1" in
                git*|tig) ;;
                -*)     set git log "$@" ;;
                *)      set git "$@" ;;
                esac
        fi

        not=$(git for-each-ref --format='%(refname)' "refs/bisect/good-*")
        eval '"$@"' refs/bisect/bad --not $not -- $(cat "$GIT_DIR/BISECT_NAMES")
}

bisect_reset() {
        test -s "$GIT_DIR/BISECT_START" || {
                echo "We are not bisecting."
                return
        }
        case "$#" in
        0) branch=$(cat "$GIT_DIR/BISECT_START") ;;
        1) git show-ref --verify --quiet -- "refs/heads/$1" ||
               die "$1 does not seem to be a valid branch"
           branch="$1" ;;
        *)
            usage ;;
        esac
        git checkout "$branch" -- && bisect_clean_state
}

bisect_clean_state() {
        # There may be some refs packed during bisection.
        git for-each-ref --format='%(refname) %(objectname)' refs/bisect/\* |
        while read ref hash
        do
                git update-ref -d $ref $hash || exit
        done
        rm -f "$GIT_DIR/BISECT_EXPECTED_REV" &&
        rm -f "$GIT_DIR/BISECT_ANCESTORS_OK" &&
        rm -f "$GIT_DIR/BISECT_LOG" &&
        rm -f "$GIT_DIR/BISECT_NAMES" &&
        rm -f "$GIT_DIR/BISECT_RUN" &&
        # Cleanup head-name if it got left by an old version of git-bisect
        rm -f "$GIT_DIR/head-name" &&

        rm -f "$GIT_DIR/BISECT_START"
}

bisect_replay () {
        test -r "$1" || die "cannot read $1 for replaying"
        bisect_reset
        while read git bisect command rev
        do
                test "$git $bisect" = "git bisect" -o "$git" = "git-bisect" || continue
                if test "$git" = "git-bisect"; then
                        rev="$command"
                        command="$bisect"
                fi
                case "$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
    help)
        git bisect -h ;;
    start)
        bisect_start "$@" ;;
    bad|good)
        bisect_state "$cmd" "$@" ;;
    skip)
        bisect_skip "$@" ;;
    next)
        # Not sure we want "next" at the UI level anymore.
        bisect_next "$@" ;;
    visualize|view)
        bisect_visualize "$@" ;;
    reset)
        bisect_reset "$@" ;;
    replay)
        bisect_replay "$@" ;;
    log)
        cat "$GIT_DIR/BISECT_LOG" ;;
    run)
        bisect_run "$@" ;;
    *)
        usage ;;
    esac
esac