const fs = require('fs');
const path = require('path');
const { parse } = require('csv-parse/sync');

const REQUIRED_HEADERS = ['登録先', '開始日', '開始時刻', '終了日', '終了時刻', '分類', '予定', '備考'];
const INPUT_DIR = path.join(__dirname, 'data');
const OUTPUT_DIR = path.join(__dirname, 'ical');

function formatDateTime(dateText, timeText) {
    const [year, month, day] = String(dateText || '').split('/').map(Number);
    const [hour, minute] = String(timeText || '').split(':').map(Number);

    if (!year || !month || !day || Number.isNaN(hour) || Number.isNaN(minute)) {
        throw new Error(`日時形式が不正です: ${dateText} ${timeText}`);
    }

    const yyyy = String(year).padStart(4, '0');
    const MM = String(month).padStart(2, '0');
    const dd = String(day).padStart(2, '0');
    const HH = String(hour).padStart(2, '0');
    const mm = String(minute).padStart(2, '0');

    return `${yyyy}${MM}${dd}T${HH}${mm}00`;
}

function getUtcStamp() {
    const now = new Date();
    const yyyy = String(now.getUTCFullYear()).padStart(4, '0');
    const MM = String(now.getUTCMonth() + 1).padStart(2, '0');
    const dd = String(now.getUTCDate()).padStart(2, '0');
    const HH = String(now.getUTCHours()).padStart(2, '0');
    const mm = String(now.getUTCMinutes()).padStart(2, '0');
    const ss = String(now.getUTCSeconds()).padStart(2, '0');
    return `${yyyy}${MM}${dd}T${HH}${mm}${ss}Z`;
}

function escapeIcalText(value) {
    return String(value || '')
        .replace(/\\/g, '\\\\')
        .replace(/\r\n|\n|\r/g, '\\n')
        .replace(/,/g, '\\,')
        .replace(/;/g, '\\;');
}

function validateHeaders(headers) {
    const normalized = headers.map(v => String(v || '').trim());
    const invalid = REQUIRED_HEADERS.some((expected, index) => normalized[index] !== expected);
    if (invalid) {
        throw new Error(`ヘッダー不一致です。期待: ${REQUIRED_HEADERS.join(', ')}`);
    }
}

function createIcsEvent(record, index) {
    const start = formatDateTime(record['開始日'], record['開始時刻']);
    const end = formatDateTime(record['終了日'], record['終了時刻']);
    const summary = escapeIcalText(record['予定']);

    const descriptionParts = [];
    //if (record['登録先']) descriptionParts.push(`登録先: ${record['登録先']}`);
    if (record['分類']) descriptionParts.push(`分類: ${record['分類']}`);
    if (record['備考']) descriptionParts.push(`備考: ${record['備考']}`);
    const description = escapeIcalText(descriptionParts.join('\n'));

    const uid = `${Date.now()}-${index}-${Math.random().toString(36).slice(2)}@alpha-office`;

    let eventText = 'BEGIN:VEVENT\n';
    eventText += `UID:${uid}\n`;
    eventText += `DTSTAMP:${getUtcStamp()}\n`;
    eventText += `DTSTART;TZID=Asia/Tokyo:${start}\n`;
    eventText += `DTEND;TZID=Asia/Tokyo:${end}\n`;
    eventText += `SUMMARY:${summary}\n`;
    eventText += `DESCRIPTION:${description}\n`;
    eventText += 'END:VEVENT\n';

    return eventText;
}

function csvToIcal(csvFileName) {
    try {
        const csvPath = path.join(INPUT_DIR, csvFileName);
        const csvContent = fs.readFileSync(csvPath, 'utf-8');

        // ダブルクォーテーションと引用符内改行を含むCSVを正しく解析
        const records = parse(csvContent, {
            columns: true,
            skip_empty_lines: true,
            bom: true
        });

        if (records.length === 0) {
            throw new Error('データ行がありません');
        }

        validateHeaders(Object.keys(records[0]));

        let ical = 'BEGIN:VCALENDAR\n';
        ical += 'VERSION:2.0\n';
        ical += 'PRODID:-//Alpha Office Schedule//JP\n';
        ical += 'CALSCALE:GREGORIAN\n';
        ical += 'METHOD:PUBLISH\n';

        records.forEach((record, index) => {
            ical += createIcsEvent(record, index);
        });

        ical += 'END:VCALENDAR\n';

        const outputPath = path.join(OUTPUT_DIR, `${path.basename(csvFileName, '.csv')}.ics`);
        fs.writeFileSync(outputPath, ical, 'utf-8');

        console.log(`✓ 変換完了: ${outputPath}`);
        return true;
    } catch (error) {
        console.error(`✗ 変換失敗 (${csvFileName}):`, error.message);
        return false;
    }
}

function main() {
    if (!fs.existsSync(INPUT_DIR)) {
        console.error(`入力フォルダが見つかりません: ${INPUT_DIR}`);
        process.exitCode = 1;
        return;
    }

    if (!fs.existsSync(OUTPUT_DIR)) {
        fs.mkdirSync(OUTPUT_DIR, { recursive: true });
    }

    const files = fs.readdirSync(INPUT_DIR)
        .filter(file => file.toLowerCase().endsWith('.csv'))
        .sort();

    if (files.length === 0) {
        console.log('csvフォルダにCSVファイルがありません');
        return;
    }

    let successCount = 0;
    let failCount = 0;

    files.forEach(file => {
        if (csvToIcal(file)) {
            successCount += 1;
        } else {
            failCount += 1;
        }
    });

    console.log(`処理結果: 成功 ${successCount} / 失敗 ${failCount}`);
    if (failCount > 0) {
        process.exitCode = 1;
    }
}

main();