#!/usr/bin/env bash

print_usage() {
    echo "Usage:"
    echo "  $0"
    echo "  $0 <commit-hash>"
    echo "  $0 --message \"<commit-message>\""
    echo "  $0 --message-file <file-path>"
}

load_commit_message() {
    if [ $# -eq 0 ]; then
        local commit_ref="HEAD"
        echo "Checking latest commit..." >&2
        git log -1 --pretty=format:"%s%n%b" "$commit_ref"
        return
    fi

    case "$1" in
        -h|--help)
            print_usage
            exit 0
            ;;
        --message)
            shift
            if [ $# -eq 0 ]; then
                echo "[FAIL] --message option requires a commit message"
                print_usage
                exit 1
            fi
            echo "Checking provided commit message..." >&2
            printf '%s' "$*"
            ;;
        --message-file)
            shift
            if [ $# -ne 1 ]; then
                echo "[FAIL] --message-file option requires a file path"
                print_usage
                exit 1
            fi
            if [ ! -f "$1" ]; then
                echo "[FAIL] Commit message file not found: $1"
                exit 1
            fi
            echo "Checking commit message file: $1" >&2
            cat "$1"
            ;;
        *)
            if [ $# -ne 1 ]; then
                echo "[FAIL] Invalid arguments"
                print_usage
                exit 1
            fi

            local commit_ref="$1"
            if ! git rev-parse --verify "$commit_ref^{commit}" >/dev/null 2>&1; then
                echo "[FAIL] Invalid commit reference: $commit_ref"
                exit 1
            fi

            echo "Checking commit: $commit_ref" >&2
            git log -1 --pretty=format:"%s%n%b" "$commit_ref"
            ;;
    esac
}

commit_message=$(load_commit_message "$@")
subject=$(printf '%s\n' "$commit_message" | head -n1)
body=$(printf '%s\n' "$commit_message" | tail -n +2)

echo "Checking commit message format..."
echo "Subject: $subject"

exit_code=0

if [ -z "$subject" ]; then
    echo "[FAIL] Subject must not be empty"
    exit 1
fi

subject_pattern='^([a-z]+)(\([a-z0-9._/-]+\))?(!)?: (.+)$'
if [[ "$subject" =~ $subject_pattern ]]; then
    type="${BASH_REMATCH[1]}"
    description="${BASH_REMATCH[4]}"

    echo "[PASS] Subject follows Conventional Commit format"
    echo "[PASS] Type is lowercase: $type"

    if printf '%s\n' "$description" | grep -Eq '[가-힣]'; then
        echo "[PASS] Description contains Korean text"
    else
        echo "[FAIL] Description must contain Korean text"
        exit_code=1
    fi
else
    echo "[FAIL] Subject must match: <type>(scope): <description>"
    echo "       scope is optional, example: feat: 기능을 추가한다"
    exit_code=1
fi

if [ -n "$body" ] && printf '%s\n' "$body" | grep -Eq '^Refs:'; then
    while IFS= read -r refs_line; do
        if ! printf '%s\n' "$refs_line" | grep -Eq '^Refs: #[0-9]+(, #[0-9]+)*$'; then
            echo "[FAIL] Refs footer format is invalid: $refs_line"
            echo "       expected format: Refs: #123 or Refs: #123, #456"
            exit_code=1
        fi
    done < <(printf '%s\n' "$body" | grep -E '^Refs:')

    if [ $exit_code -eq 0 ]; then
        echo "[PASS] Refs footer format is valid"
    fi
fi

if [ $exit_code -eq 0 ]; then
    echo "[PASS] Commit message follows AGENTS.md rules"
else
    echo "[FAIL] Commit message violates AGENTS.md rules"
fi

exit $exit_code