#!/usr/bin/env bash
set -euo pipefail

# A hook script to check the commit log message.
# 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.

# This script focuses on enforcing semantic commit message specification.
#
# It primarily focuses on the commit title, however, it also enforces some
# the mandatory newline between the title and the body.

LIGHT_GRAY="\033[0;37m"
YELLOW="\033[33m"
CYAN="\033[36m"
RED="\033[31m"
UNDO_COLOR="\033[0m"

check_dependencies() {
  if ! [ -x "$(command -v jq)" ]; then
    echo "\`commit-msg\` hook failed. Please install jq."
    exit 1
  fi
}

load_config() {
  config_file="$PWD/.commit-msg-config.json"

  if [ ! -f "$config_file" ]; then
    exit 0
  fi

  enabled=$(jq -r .enabled "$config_file")

  if [ "$enabled" != "true" ]; then
    exit 0
  fi

  title_semver_enabled=$(jq -r .semver_structure "$config_file")
  mapfile -t special_types < <(jq -r '.special_types[]' "$config_file")
  mapfile -t types < <(jq -r '.types[]' "$config_file")
  mapfile -t scopes < <(jq -r '.scopes[]' "$config_file")
  title_min_length=$(jq -r '.length.min' "$config_file")
  title_max_length=$(jq -r '.length.max' "$config_file")
}

# Build a dynamic regex for the commit message
build_title_regex() {
  regexp="^("

  # Special types
  if [ ${#special_types[@]} -eq 0 ]; then
    for s_type in "${special_types[@]}"; do
      regexp="${regexp}$s_type|"
    done
    regexp="${regexp%|})"

    regexp="${regexp}(: .+)?"

    regexp="${regexp}$|^("
  fi

  # Types
  if [ ${#types[@]} -eq 0 ]; then
    regexp="${regexp}.+"
  else
    for type in "${types[@]}"; do
      regexp="${regexp}$type|"
    done
    regexp="${regexp%|})"
  fi

  # Scope
  regexp="${regexp}(\("
  if [ ${#scopes[@]} -eq 0 ]; then
    regexp="${regexp}.+"
  else
    for scope in "${scopes[@]}"; do
      regexp="${regexp}$scope|"
    done
    regexp="${regexp%|}"
  fi
  regexp="${regexp}\))?"

  # Breaking change indicator
  regexp="${regexp}(!)?"

  regexp="${regexp}: (.+)$"
}

error_header() {
  echo -e "${RED}[Invalid Commit Message]${UNDO_COLOR}"
  echo -e "------------------------"
}

# ---------------------------------------------

INPUT_FILE="$1"

check_dependencies
load_config

# Get the actual commit message, excluding comments
commit_message=$(sed '/^#/d' <"$INPUT_FILE")

# Don't do any checking on empty commit messages.
# Git will abort empty commits by default anyways.
if [ -z "$commit_message" ]; then
  exit 0
fi

commit_title=$(echo "$commit_message" | head -n1 "$INPUT_FILE")

# Check the semver commit title structure first
if [ "$title_semver_enabled" == "true" ]; then
  build_title_regex

  if [[ ! $commit_title =~ $regexp ]]; then
    error_header
    echo -e "${LIGHT_GRAY}Valid types: ${UNDO_COLOR}${CYAN}${types[*]}${UNDO_COLOR}"
    echo -e "${LIGHT_GRAY}Valid special types: ${UNDO_COLOR}${CYAN}${special_types[*]}${UNDO_COLOR}"
    if [ ${#scopes[@]} -eq 0 ]; then
      echo -e "${LIGHT_GRAY}Valid scopes: any${UNDO_COLOR}"
    else
      echo -e "${LIGHT_GRAY}Valid scopes: ${UNDO_COLOR}${CYAN}${scopes[*]}${UNDO_COLOR}"
    fi

    #echo -e "${LIGHT_GRAY}Expected regex: ${UNDO_COLOR}${CYAN}${regexp}${UNDO_COLOR}"

    echo -e "Actual commit title: ${YELLOW}${commit_title}${UNDO_COLOR}"
    exit 1
  fi
fi

# Then check the length of the commit title
commit_title_len=${#commit_title}
if { [ "$title_min_length" != "null" ] && [ "$commit_title_len" -lt "$title_min_length" ]; } ||
  { [ "$title_max_length" != "null" ] && [ "$commit_title_len" -gt "$title_max_length" ]; }; then
  error_header
  echo -e "${LIGHT_GRAY}Expected title (first line) length: Min=${CYAN}$title_min_length${UNDO_COLOR} Max=${CYAN}$title_max_length${UNDO_COLOR}"
  echo -e "Actual length: ${YELLOW}${commit_title_len}${UNDO_COLOR}"
  exit 1
fi

# Check for a newline between the title and the body
if [ "$(echo "$commit_message" | wc -l)" -gt 1 ]; then
  second_line=$(echo "$commit_message" | sed -n '2p')
  third_line=$(echo "$commit_message" | sed -n '3p')
  if [ "$second_line" != "" ] || [ "$third_line" == "" ]; then
    error_header
    echo -e "There must be exactly one blank line between the commit title and the body."
    exit 1
  fi
fi