#!/usr/bin/env bash

#
# This commit-msg hook validates commit messages
# to ensure that they meet our conventional commit standard.
#
#
#   "type: message"
#   "type(scope): message"
#   Optionally, append ". Fixes #1234"
#
# Reference: https://github.com/keymanapp/keyman/wiki/Pull-Request-and-Commit-workflow-notes
#

# Get the directory where this script lives, i.e. resources/git-hooks
HOOK_DIRECTORY="$(dirname "$(readlink -f "${BASH_SOURCE[0]}")")"

if [ -f $(dirname "${BASH_SOURCE[0]}")/commit-msg-defs ]; then
  # This script was run from a symlink and the repo in question has its own commit-msg-defs.
  . $(dirname "${BASH_SOURCE[0]}")/commit-msg-defs
else
  # We'll grab the settings from the keymanapp/keyman repository.
  . "$HOOK_DIRECTORY/../build/jq.inc.sh"

  # Configurable options for message length.
  min_length=4
  max_length=128

  # Read from our globally shared JSON-formatted scopes and types
  scopes=( $("$JQ" -r '[.scopes | paths | reduce .[] as $item (""; if . == "" then $item else . + "/" + $item end)] | join(" ")' < "$HOOK_DIRECTORY/../scopes/scopes.json") )
  types=( $("$JQ" -r '.commitTypes | join(" ")' < "$HOOK_DIRECTORY/../scopes/commit-types.json") )
fi

#
# Define terminal colours.
#

if [ -t 2 ]; then
  t_red=$'\e[1;31m'
  t_grn=$'\e[1;32m'
  t_yel=$'\e[1;33m'
  t_blu=$'\e[1;34m'
  t_mag=$'\e[1;35m'
  t_cyn=$'\e[1;36m'
  t_end=$'\e[0m'
fi

#
# Test the repository upstream/origin: ignore if not keymanapp/keyman
#

GIT_ORIGIN="$(git remote get-url origin)"

if [[ ! "$GIT_ORIGIN" =~ github\.com(/|:)keymanapp ]]; then
  # Not a Keyman repository. We have no opinion.
  # echo "DEBUG: Not a Keyman repository. We don't care"
  exit 0
fi


if [[ "$GIT_ORIGIN" =~ keyboards|lexical-models ]]; then
  # We don't enforce commit messages on keyboards or lexical-models repositories
  # echo "DEBUG: Keyboards or Lexical-Models. We still don't care."
  exit 0
fi

# If this script is called by another hook, it may insert a -q parameter to silence the help text.
QUIET=0
case $1 in
  -q|--quiet)
    shift   # Remove the parameter, making it equivalent to a standard git-hook call.
    QUIET=1
    ;;
esac

# build the regex pattern based on the config file
function build_regex() {
  retypes=
  for type in "${types[@]}"
  do
    retypes="${retypes}$type|"
  done
  retypes="(${retypes%?})"

  rescope=
  for scope in "${scopes[@]}"
  do
    rescope="${rescope}$scope|"
  done
  # %? removes last |
  rescope="(\((${rescope%?})\))?"

  remessage=".{$min_length,$max_length}[^.]"
  refixes="(\. Fixes #[[:digit:]]+)?"

  # Regex for the commit message title. It's ok if the commit message starts with "fixup!".
  # (This allows to run `git commit --fixup=<sha>` without complaining about the commit
  # message not being in conventional commit format. This helps in squashing with a previous
  # commit.)
  regexp="^(fixup\! )?${retypes}${rescope}: ${remessage}${refixes}[[:space:]]*$"
}

# Print out a standard error message which explains
# how the commit message should be structured
function print_error() {
  echo -e "\n${t_red}ERROR: Commit message is not in Conventional Commit format"
  echo -e "----------------------------------------------------------${t_end}"
  echo -e "Valid types: ${t_grn}${types[@]}${t_end}"
  echo -e "Valid scopes: ${t_grn}${scopes[@]}${t_end}"
  echo -e ""
  echo -e "Min length (first line): ${t_grn}$min_length${t_end}"
  echo -e "Max length (first line): ${t_grn}$max_length${t_end}"
  echo -e ""
  echo -e "If possible, append git trailers:"
  echo -e " * ${t_grn}Fixes: #1234${t_end}"
  echo -e " * ${t_grn}Fixes: KEYMAN-MODULE-XYZ${t_end}"
  echo -e " * ${t_grn}Cherry-pick-of: #2468${t_end}"
  echo -e " * ${t_grn}Co-authored-by: Firstname Lastname <email@keyman.com>${t_end}"
  echo -e ""
  echo -e "${t_cyn}Example:${t_end} fix(windows): Re-attach the widget plug which had fallen out"
  echo -e ""
  echo -e "${t_cyn}Reference${t_end}: https://github.com/keymanapp/keyman/wiki/Pull-Request-and-Commit-workflow-notes"
  echo -e ""
  echo -e "Tips: "
  echo -e " * Don't include a period at the end of the title"
  echo -e " * Always include a blank line before trailers"
  echo -e " * Use imperative, present tense ('attach' instead of 'attaches', 'attached' etc)"
  echo -e ""
  echo -e "This script: $0"
}

# get the first line of the commit message
msg=$(head -1 $1)

build_regex

if [[ ! $msg =~ $regexp ]]; then
  # commit message is invalid according to config - block commit
  if [ $QUIET -eq 0 ]; then
    print_error
  fi
  exit 1
fi