#!/bin/bash
#
# A hook script to check the commit log message to ensure that it has
# a well-formed commit summary and body, a valid Signed-off-by: line,
# and a Gerrit Change-Id: line (added automatically if missing).
#
# Called by git-commit with one argument, the name of the file
# that has the commit message.  The hook should exit with non-zero
# status after issuing an appropriate message if it wants to stop the
# commit.  The hook is allowed to edit the commit message file.
#
# Should be installed as .git/hooks/commit-msg.
#

init() {
        set -a
        readonly ORIGINAL="$1"
        readonly REVISED="$(mktemp "$ORIGINAL.XXXXXX")"
        readonly SAVE="$(basename $ORIGINAL).$(date +%Y%m%d.%H%M%S)"
        readonly SIGNOFF="Signed-off-by:"
        readonly CHANGEID="Change-Id:"
        readonly TESTPARAMS="Test-Parameters:"
        readonly INNOCUOUS=$(echo \
                        Acked-by \
                        Tested-by \
                        Reported-by \
                        Reviewed-by \
                        CC \
                | tr ' ' '|')
        readonly WIDTH_SUM=62
        readonly WIDTH_REG=70
        readonly JIRA_FMT_A="^[A-Z]\{2,5\}-[0-9]\{1,5\} [-a-z0-9]\{2,11\}: "
        readonly JIRA_FMT_B="^[A-Z]\{2,5\}-[0-9]\{1,5\} "

        # Identify a name followed by an email address.
        #
        readonly EMAILPAT=$'[ \t]*[^<> ]* [^<>]* <[^@ \t>]+@[a-zA-Z0-9.-]+\.[a-z]+>'

        HAS_ERROR=false
        HAS_SUMMARY=false
        HAS_LAST_BLANK=false
        HAS_BODY=false
        HAS_SIGNOFF=false
        HAS_CHANGEID=false

        IS_WRAPPING_UP=false

        LINE=""
        NUM=0
        set +a
}

# die: commit-msg fatal error: script error or empty input message
# All output redirected to stderr.
#
die() {
        echo "commit-msg fatal error:  $*"
        test -f "$REVISED" && rm -f "$REVISED"
        exit 1
} 1>&2

# Called when doing the final "wrap up" clause because we've found
# one of the tagged lines that belongs in the final section.
#
function ck_wrapup() {
        $IS_WRAPPING_UP && return

        $HAS_LAST_BLANK || error "blank line must preceed signoff section"
        $HAS_SUMMARY    || error "missing commit summary line."
        $HAS_BODY       || error "missing commit description."

        HAS_LAST_BLANK=false
        IS_WRAPPING_UP=true
}

function do_signoff() {
        ck_wrapup
        # Signed-off-by: First Last <email@host.domain>
        local txt=$(echo "${LINE#*: }" | grep -E "${EMAILPAT}")
        if (( ${#txt} == 0 )); then
                error "$SIGNOFF line requires name and email address"
        else
                HAS_SIGNOFF=true # require at least one
        fi
}

function do_changeid() {
        ck_wrapup
        $HAS_CHANGEID && error "multiple $CHANGEID lines are not allowed"

        # Change-Id: I1234567890123456789012345678901234567890
        # capital "I" plus 40 hex digits
        #
        local txt=$(echo "$LINE" | grep "^$CHANGEID I[0-9a-fA-F]\{40\}\$")
        (( ${#txt} > 0 )) ||
                error "has invalid $CHANGEID line for Gerrit tracking"

        HAS_CHANGEID=true
}

# All "innocuous" lines specify a person and email address
#
function do_innocuous() {
        ck_wrapup
        local txt=$(echo "${LINE#*: }" | grep -E "${EMAILPAT}")
        (( ${#txt} == 0 )) && error "invalid name and address"
}

function do_default_line() {
        $IS_WRAPPING_UP && {
                error "invalid signoff section line"
                return
        }
        if (( NUM == 1 )); then
                HAS_JIRA_COMPONENT=$(echo "$LINE" | grep "$JIRA_FMT_A")

                if (( ${#HAS_JIRA_COMPONENT} == 0 )); then
                        HAS_JIRA=$(echo "$LINE" | grep "$JIRA_FMT_B")
                        if (( ${#HAS_JIRA} > 0 )); then
                                error "has no component in summary."
                        else
                                error "missing JIRA ticket number."
                        fi
                elif (( ${#LINE} > WIDTH_SUM )); then
                        error "summary longer than $WIDTH_SUM columns."
                else
                        HAS_SUMMARY=true
                fi

        elif (( ${#LINE} > WIDTH_REG )); then
                error "has line longer than $WIDTH_REG columns."
        elif ! $HAS_BODY && ! $HAS_LAST_BLANK; then
                error "has no blank line after summary."
        else
                HAS_BODY=true
        fi
        HAS_LAST_BLANK=false
}

# Add a new unique Change-Id
#
new_changeid() {
        local NEWID=$({
                        git var GIT_AUTHOR_IDENT
                        git var GIT_COMMITTER_IDENT
                        git write-tree
                        git rev-parse HEAD 2>/dev/null
                        grep -v "^$SIGNOFF" "$ORIGINAL" | git stripspace -s
                } | git hash-object --stdin)
        (( ${#NEWID} > 0 )) ||
                die "git hash-object failed for $CHANGEID:"

        echo "$CHANGEID I$NEWID"
}

# A commit message error was encountered.
# All output redirected to stderr.
#
error() {
        (( ${#LINE} > 0 )) && echo "line $NUM: $LINE"
        echo "error: commit message $*" | fmt
        HAS_ERROR=true
} 1>&2

usage() {
        exec 1>&2
        cat <<- EOF

	See http://wiki.whamcloud.com/display/PUB/Commit+Comments
	for full details.  An example valid commit comment is:

	LUDOC-nnn component: short description of change under 64 columns

	The "component:" should be a lower-case single-word section of the Lustre
	manual that best encompasses the change being made.  Examples of sections
	include: setup, configuration, debug. This list is not exhaustive, but is a
	guideline.

	The commit comment should contain a detailed explanation of the change
	being made.  This can be as long as you'd like.  Wrap lines at/under $WIDTH_REG
	columns.

	Finish the comment with a blank line and a blank-line-free
	sign off section:

	$SIGNOFF Your Real Name <your_email@domain.name>
	$CHANGEID Ixxxx(added automatically if missing)xxxx

	The "$CHANGEID" line should only be there when updating a previous
	commit/submission.  Copy the one from the original commit.

	The "sign off section" may also include several other tag lines:
	$(for T in $(tr '|' ' ' <<< "$INNOCUOUS"); do       \
	     echo "    $T: Some Person <email@domain.com>"; \
	  done)
	$TESTPARAMS optional additional test parameters
	{Organization}-bug-id: associated external change identifier
	EOF

        mv "$ORIGINAL" "$SAVE" &&
                echo "$0: saved original commit comment to $SAVE" 1>&2
}

init ${1+"$@"}
exec 3< "$ORIGINAL" 4> "$REVISED" || exit 1

while IFS= read -u3 LINE; do
        ((NUM += 1))
        case "$LINE" in
        $SIGNOFF* )   do_signoff   ;;
        $CHANGEID* )  do_changeid  ;;
        $TESTPARAMS* ) ck_wrapup   ;;

        "")
                HAS_LAST_BLANK=true
                $IS_WRAPPING_UP && continue
                ;;

        \#*)
                continue ## ignore and suppress comments
                ;;

        "diff --git a/"* )
                # Beginning of uncommented diffstat from "commit -v".  If
                # there are diff and index lines, skip the rest of the input:
                #   diff --git a/build/commit-msg b/build/commit-msg
                #   index 80a3442..acb4c50 100755
                #   deleted file mode 100644
                #   old mode 100644
                # If a "diff --git" line is not followed by one of these
                # lines, do the default line processing on both lines.
                #
                IFS= read -u3 INDEX || break
                ((NUM += 1))
                case "$INDEX" in
                "index "[0-9a-fA-F]*) break ;;
                "deleted file mode "*) break  ;;
                "old mode "*) break ;;
                esac
                LINE=${LINE}$'\n'${INDEX}
                do_default_line
                ;;

        *)
                if [[ "$LINE" =~ ^($INNOCUOUS): ]]; then
                        do_innocuous
                elif [[ "$LINE" =~ ^[A-Za-z0-9_-]+-bug-id: ]]; then
                        ck_wrapup
                else
                        # Allow arbitrary external bug identifiers for tracking.
                        # I can't seem to find a pattern for the "case" that
                        # checks for "*-bug-id", so this is checked here.
                        do_default_line
                fi
                ;;
        esac

        echo "$LINE" >&4
done

(( NUM <= 0 )) && die "empty commit message"

unset LINE
$HAS_SIGNOFF || error "missing valid $SIGNOFF: line."

if $HAS_ERROR; then
        exec 3<&- 4>&-
        usage
        rm "$REVISED"
        exit 1
fi

$HAS_CHANGEID || new_changeid >&4
exec 3<&- 4>&-

mv "$REVISED" "$ORIGINAL"

## Local Variables:
## Mode: shell-script
## sh-basic-offset:          8
## sh-indent-after-do:       8
## sh-indentation:           8
## sh-indent-for-case-label: 0
## sh-indent-for-case-alt:   8
## End: