/**
 * Date and Time Utilities for WIB (UTC+7) Timezone Handling
 * Implements D-1 data filtering logic for dashboard display before 17:00 WIB
 */

const CUTOFF_HOUR = process.env.CUTOFF_HOUR_OVERRIDE
    ? parseInt(process.env.CUTOFF_HOUR_OVERRIDE, 10)
    : 17;

/**
 * Get current date/time in WIB (Asia/Jakarta, UTC+7) timezone
 * @returns {Date} Current date in WIB
 */
function getCurrentWibDate() {
    const now = new Date();

    // Convert to WIB using toLocaleString with Jakarta timezone
    const wibDateString = now.toLocaleString('en-US', {
        timeZone: 'Asia/Jakarta',
        year: 'numeric',
        month: '2-digit',
        day: '2-digit',
        hour: '2-digit',
        minute: '2-digit',
        second: '2-digit',
        hour12: false
    });

    // Parse the formatted string back to Date object
    return new Date(wibDateString);
}

/**
 * Check if current WIB time is before the cutoff hour (default 17:00)
 * @returns {boolean} True if before cutoff, false otherwise
 */
function isBeforeCutoffTime() {
    const wibNow = getCurrentWibDate();
    const currentHour = wibNow.getHours();
    return currentHour < CUTOFF_HOUR;
}

/**
 * Get the effective query date (D-1 if before cutoff, else today)
 * @returns {Date} Effective date for data queries
 */
function getEffectiveQueryDate() {
    const wibToday = getCurrentWibDate();

    if (isBeforeCutoffTime()) {
        // Return D-1 (previous day)
        const yesterday = new Date(wibToday);
        yesterday.setDate(yesterday.getDate() - 1);
        return yesterday;
    }

    return wibToday;
}

/**
 * Calculate effective day of cycle accounting for D-1 filter
 * @param {Date|string} cycleStartDate - Cycle start date
 * @returns {number} Effective cycle day (0-indexed from start date)
 */
function getEffectiveCycleDay(cycleStartDate) {
    const effectiveDate = getEffectiveQueryDate();
    const startDate = new Date(cycleStartDate);

    // Reset hours to compare dates only
    effectiveDate.setHours(0, 0, 0, 0);
    startDate.setHours(0, 0, 0, 0);

    const diffMs = effectiveDate.getTime() - startDate.getTime();

    // Return -1 if effective date is before cycle start (edge case)
    if (diffMs < 0) {
        return -1;
    }

    const dayOfCycle = Math.floor(diffMs / (1000 * 60 * 60 * 24));
    return dayOfCycle;
}

/**
 * Format date as YYYY-MM-DD for database queries
 * @param {Date} date - Date object to format
 * @returns {string} Date in YYYY-MM-DD format
 */
function formatDateForDb(date) {
    const year = date.getFullYear();
    const month = String(date.getMonth() + 1).padStart(2, '0');
    const day = String(date.getDate()).padStart(2, '0');
    return `${year}-${month}-${day}`;
}

/**
 * Get previous date (D-1) from a given date
 * @param {string} dateString - Date string in YYYY-MM-DD format
 * @returns {string} Previous date in YYYY-MM-DD format
 */
function getPreviousDate(dateString) {
    const date = new Date(dateString);
    date.setDate(date.getDate() - 1);
    return formatDateForDb(date);
}

/**
 * Create API response metadata for D-1 filtering
 * @param {boolean} isD1Applied - Whether D-1 filter was applied
 * @returns {object} Metadata object for API response
 */
function createResponseMetadata(isD1Applied = false) {
    const wibNow = getCurrentWibDate();
    const effectiveDate = getEffectiveQueryDate();

    return {
        effectiveDate: formatDateForDb(effectiveDate),
        queryDate: formatDateForDb(wibNow),
        isD1Filter: isD1Applied,
        currentWibTime: wibNow.toLocaleTimeString('id-ID', {
            timeZone: 'Asia/Jakarta',
            hour: '2-digit',
            minute: '2-digit'
        })
    };
}

module.exports = {
    getCurrentWibDate,
    isBeforeCutoffTime,
    getEffectiveQueryDate,
    getEffectiveCycleDay,
    formatDateForDb,
    getPreviousDate,
    createResponseMetadata,
    CUTOFF_HOUR // Export for testing
};