#!/usr/bin/env bash
# shellcheck disable=SC2059
#
# Check git commits for compliance with hledger's conventions,
# described at https://hledger.org/CONTRIBUTING.html#commit-messages.
#
# Usage:
# commitlint [GITREV|GITRANGE]
#   Checks unpushed commits, or the specified commit or range.
#   If the argument contains - or .. it's a range, otherwise a single commit.
#
# Examples:
# commitlint                              # unpushed commits
# commitlint HEAD                         # last commit
# commitlint d5d19f841                    # this commit
# commitlint -20                          # last 20 commits
# commitlint master..                     # commits in this branch
# commitlint 1.21..1.22 | grep -F [FAIL]  # bad commits in 1.22 release cycle

if [[ -n ${NO_COLOR+set} ]]
then
    RED=""
    GRN=""
    NRM=""
else
    RED="\033[31m"
    GRN="\033[32m"
    NRM="\033[0m"
fi

# checkcommit GITHASH - check this commit's message and print result
function checkcommit()
{
    HASH=${1}
    SUMMARY=$(git log -1 "$HASH" --pretty=format:"%s")

    # Does the summary have a type: prefix ?
    # Can begin with ; and/or end with !, some spaces are tolerated.
    FMT="%s %-60s  %b${NRM}\n"
    if ! echo "$SUMMARY" | grep -qE '^(; *)?\w+:[ \w]+!?'
    then
        printf "$FMT" "$HASH" "$SUMMARY" "${RED}[FAIL]"
        STATUS=1
    else
        printf "$FMT" "$HASH" "$SUMMARY" "${GRN}[ok]"
    fi
}

RANGE=${*:-"@{u}.."}  # @{u} = upstream

if [[ ! $RANGE =~ (-|\.\.) ]]
then
    RANGE=$RANGE^!  # assume range is a single commit
fi

HASHES=$(git log --abbrev-commit --pretty=format:%h "$RANGE")

STATUS=
for HASH in $HASHES; do
    checkcommit "$HASH"
done

if [[ -z $STATUS ]]
then
    printf "" # "${GRN}Ok${NRM}\n"
else
    printf "\n${RED}Some commits are not in preferred style.${NRM}\n"
    cat <<EOF
---------------------------------------------------------------------------
Commit messages should follow this format:

  [;]type[!]: [topic:] summary

  [Optional description, ready for release notes/changelog.]

Explanation:

The subject line should have a type: prefix. Common types:
 feat imp fix            - end-user changes (->release notes & changelogs)
 cha pkg lib             - packager/builder/lib-user changes (->changelogs)
 dev doc test ci ref cln - developer changes

It may additionally have a topic prefix such as:
 (see https://hledger.org/CONTRIBUTING.html#open-issues -> COMPONENT)

Mention any related issues, usually parenthesised at end of summary: (#1234)
! indicates a breaking change.
; skips expensive CI tests.

These conventions are evolving. In practice, any type or topic will
do. Use your best judgement and we'll polish during code review.
More detail: https://hledger.org/CONTRIBUTING.html#commit-messages
---------------------------------------------------------------------------
EOF

fi

exit 0"$STATUS"