/**
 * Vernova - Lightweight Vanilla JS Jalali Date Picker
 * No jQuery, no eval, no external dependencies. CSP-safe.
 */
(function () {
    'use strict';

    // ─── Jalali ↔ Gregorian Conversion ─────────────────────────
    var JalaliConverter = {
        gregorianToJalali: function (gy, gm, gd) {
            var g_d_m = [0, 31, 59, 90, 120, 151, 181, 212, 243, 273, 304, 334];
            var gy2 = (gm > 2) ? (gy + 1) : gy;
            var days = 355666 + (365 * gy) + Math.floor((gy2 + 3) / 4) - Math.floor((gy2 + 99) / 100) + Math.floor((gy2 + 399) / 400) + gd + g_d_m[gm - 1];
            var jy = -1595 + (33 * Math.floor(days / 12053));
            days %= 12053;
            jy += 4 * Math.floor(days / 1461);
            days %= 1461;
            if (days > 365) {
                jy += Math.floor((days - 1) / 365);
                days = (days - 1) % 365;
            }
            var jm, jd;
            if (days < 186) {
                jm = 1 + Math.floor(days / 31);
                jd = 1 + (days % 31);
            } else {
                jm = 7 + Math.floor((days - 186) / 30);
                jd = 1 + ((days - 186) % 30);
            }
            return [jy, jm, jd];
        },
        jalaliToGregorian: function (jy, jm, jd) {
            var jy2 = jy - 979;
            var jm2 = jm - 1;
            var jd2 = jd - 1;
            var days = 365 * jy2 + Math.floor(jy2 / 33) * 8 + Math.floor((jy2 % 33 + 3) / 4) + 78 + jd2 + ((jm2 < 7) ? (jm2 * 31) : ((jm2 * 30) + 6));
            var gy = 1600 + 400 * Math.floor(days / 146097);
            days %= 146097;
            if (days > 36524) {
                gy += 100 * Math.floor(--days / 36524);
                days %= 36524;
                if (days >= 365) days++;
            }
            gy += 4 * Math.floor(days / 1461);
            days %= 1461;
            if (days > 365) {
                gy += Math.floor((days - 1) / 365);
                days = (days - 1) % 365;
            }
            var gd = days + 1;
            var sal_a = [0, 31, ((gy % 4 === 0 && gy % 100 !== 0) || (gy % 400 === 0)) ? 29 : 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
            var gm;
            for (gm = 0; gm < 13 && gd > sal_a[gm]; gm++) gd -= sal_a[gm];
            return [gy, gm, gd];
        },
        isJalaliLeap: function (jy) {
            var breaks = [1, 5, 9, 13, 17, 22, 26, 30];
            var r = jy % 33;
            return breaks.indexOf(r) !== -1;
        },
        jalaliMonthDays: function (jy, jm) {
            if (jm <= 6) return 31;
            if (jm <= 11) return 30;
            return this.isJalaliLeap(jy) ? 30 : 29;
        },
        gregorianMonthDays: function (gy, gm) {
            var days = [0, 31, ((gy % 4 === 0 && gy % 100 !== 0) || (gy % 400 === 0)) ? 29 : 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31];
            return days[gm];
        }
    };

    // ─── Jalali Month/Day Names ────────────────────────────────
    var jalaliMonths = ['فروردین', 'اردیبهشت', 'خرداد', 'تیر', 'مرداد', 'شهریور', 'مهر', 'آبان', 'آذر', 'دی', 'بهمن', 'اسفند'];
    var jalaliWeekDaysShort = ['ش', 'ی', 'د', 'س', 'چ', 'پ', 'ج'];
    var jalaliWeekDaysLong = ['شنبه', 'یکشنبه', 'دوشنبه', 'سه‌شنبه', 'چهارشنبه', 'پنجشنبه', 'جمعه'];

    // ─── Pad helper ────────────────────────────────────────────
    function pad(n) { return n < 10 ? '0' + n : '' + n; }

    // ─── Date Picker Class ─────────────────────────────────────
    function JalaliDatePicker(inputEl, hiddenEl) {
        this.inputEl = inputEl;
        this.hiddenEl = hiddenEl;
        this.container = null;
        this.isOpen = false;
        this.currentYear = 1404;
        this.currentMonth = 1;
        this.selectedYear = null;
        this.selectedMonth = null;
        this.selectedDay = null;

        this._init();
    }

    JalaliDatePicker.prototype = {
        _init: function () {
            // Parse initial value
            var val = this.inputEl.value;
            if (val && /^\d{4}\/\d{1,2}\/\d{1,2}$/.test(val)) {
                var parts = val.split('/');
                this.selectedYear = this.currentYear = parseInt(parts[0]);
                this.selectedMonth = this.currentMonth = parseInt(parts[1]);
                this.selectedDay = parseInt(parts[2]);
            } else {
                // Default to today
                var now = new Date();
                var today = JalaliConverter.gregorianToJalali(now.getFullYear(), now.getMonth() + 1, now.getDate());
                this.currentYear = today[0];
                this.currentMonth = today[1];
            }

            // Create container
            this.container = document.createElement('div');
            this.container.className = 'jalali-picker-dropdown';
            this.container.style.display = 'none';
            document.body.appendChild(this.container);

            // Bind events
            var self = this;
            this.inputEl.addEventListener('focus', function (e) { self.open(); });
            this.inputEl.addEventListener('click', function (e) { e.stopPropagation(); });
            this.container.addEventListener('click', function (e) { e.stopPropagation(); });

            // Close on outside click
            document.addEventListener('click', function (e) {
                if (self.isOpen && e.target !== self.inputEl && !self.container.contains(e.target)) {
                    self.close();
                }
            });

            // Handle manual input
            this.inputEl.addEventListener('blur', function () {
                self._syncFromInput();
            });

            // Handle keyboard
            this.inputEl.addEventListener('keydown', function (e) {
                if (e.key === 'Escape') self.close();
                if (e.key === 'Enter') { self._syncFromInput(); self.close(); }
            });
        },

        _syncFromInput: function () {
            var val = this.inputEl.value.trim();
            if (/^\d{4}\/\d{1,2}\/\d{1,2}$/.test(val)) {
                var parts = val.split('/');
                var jy = parseInt(parts[0]), jm = parseInt(parts[1]), jd = parseInt(parts[2]);
                var maxDay = JalaliConverter.jalaliMonthDays(jy, jm);
                if (jd > maxDay) jd = maxDay;
                this.selectedYear = jy;
                this.selectedMonth = jm;
                this.selectedDay = jd;
                this.inputEl.value = pad(jy) + '/' + pad(jm) + '/' + pad(jd);
                this._updateHidden();
            } else if (val === '') {
                this.selectedYear = null;
                this.selectedMonth = null;
                this.selectedDay = null;
                if (this.hiddenEl) this.hiddenEl.value = '';
            }
        },

        _updateHidden: function () {
            if (this.selectedYear && this.selectedMonth && this.selectedDay) {
                var g = JalaliConverter.jalaliToGregorian(this.selectedYear, this.selectedMonth, this.selectedDay);
                var gregStr = pad(g[0]) + '-' + pad(g[1]) + '-' + pad(g[2]);
                if (this.hiddenEl) this.hiddenEl.value = gregStr;
            }
        },

        open: function () {
            this._render();
            this.container.style.display = 'block';
            this.isOpen = true;
            this._position();
        },

        close: function () {
            this.container.style.display = 'none';
            this.isOpen = false;
        },

        _position: function () {
            var rect = this.inputEl.getBoundingClientRect();
            var scrollTop = window.pageYOffset || document.documentElement.scrollTop;
            var scrollLeft = window.pageXOffset || document.documentElement.scrollLeft;
            var pickerHeight = this.container.offsetHeight;
            var spaceBelow = window.innerHeight - rect.bottom;
            var spaceAbove = rect.top;

            this.container.style.position = 'absolute';
            if (spaceBelow < pickerHeight && spaceAbove > spaceBelow) {
                this.container.style.top = (rect.top + scrollTop - pickerHeight - 4) + 'px';
            } else {
                this.container.style.top = (rect.bottom + scrollTop + 4) + 'px';
            }
            // RTL: align to right edge
            this.container.style.left = (rect.right + scrollLeft - this.container.offsetWidth) + 'px';
        },

        _render: function () {
            var self = this;
            var y = this.currentYear;
            var m = this.currentMonth;

            // First day of month in Gregorian
            var firstGreg = JalaliConverter.jalaliToGregorian(y, m, 1);
            var firstDate = new Date(firstGreg[0], firstGreg[1] - 1, firstGreg[2]);
            // Day of week: 0=Sun, adjust to Saturday=0 for Jalali
            var dow = firstDate.getDay(); // 0=Sun
            var jalaliDow = (dow + 1) % 7; // 0=Sat

            var daysInMonth = JalaliConverter.jalaliMonthDays(y, m);

            // Today
            var now = new Date();
            var todayJ = JalaliConverter.gregorianToJalali(now.getFullYear(), now.getMonth() + 1, now.getDate());

            var html = '<div class="jp-header">';
            html += '<button type="button" class="jp-nav jp-prev" data-dir="prev">&laquo;</button>';
            html += '<span class="jp-title">' + y + ' ' + jalaliMonths[m - 1] + '</span>';
            html += '<button type="button" class="jp-nav jp-next" data-dir="next">&raquo;</button>';
            html += '</div>';

            // Week day headers
            html += '<div class="jp-weekdays">';
            for (var i = 0; i < 7; i++) {
                html += '<span class="jp-wd">' + jalaliWeekDaysShort[i] + '</span>';
            }
            html += '</div>';

            // Days grid
            html += '<div class="jp-days">';
            // Empty cells before first day
            for (var i = 0; i < jalaliDow; i++) {
                html += '<span class="jp-day jp-empty"></span>';
            }
            // Day cells
            for (var d = 1; d <= daysInMonth; d++) {
                var classes = 'jp-day';
                if (y === todayJ[0] && m === todayJ[1] && d === todayJ[2]) classes += ' jp-today';
                if (y === this.selectedYear && m === this.selectedMonth && d === this.selectedDay) classes += ' jp-selected';
                html += '<button type="button" class="' + classes + '" data-day="' + d + '">' + d + '</button>';
            }
            html += '</div>';

            // Footer
            html += '<div class="jp-footer">';
            html += '<button type="button" class="jp-today-btn">امروز</button>';
            html += '</div>';

            this.container.innerHTML = html;

            // Bind navigation
            this.container.querySelector('.jp-prev').addEventListener('click', function () { self._navigate(-1); });
            this.container.querySelector('.jp-next').addEventListener('click', function () { self._navigate(1); });
            this.container.querySelector('.jp-today-btn').addEventListener('click', function () { self._goToday(); });

            // Bind day clicks
            var dayBtns = this.container.querySelectorAll('.jp-day:not(.jp-empty)');
            for (var i = 0; i < dayBtns.length; i++) {
                dayBtns[i].addEventListener('click', function () {
                    var day = parseInt(this.getAttribute('data-day'));
                    self._selectDay(self.currentYear, self.currentMonth, day);
                });
            }
        },

        _navigate: function (dir) {
            this.currentMonth += dir;
            if (this.currentMonth > 12) {
                this.currentMonth = 1;
                this.currentYear++;
            } else if (this.currentMonth < 1) {
                this.currentMonth = 12;
                this.currentYear--;
            }
            this._render();
            this._position();
        },

        _selectDay: function (y, m, d) {
            this.selectedYear = y;
            this.selectedMonth = m;
            this.selectedDay = d;
            this.inputEl.value = pad(y) + '/' + pad(m) + '/' + pad(d);
            this._updateHidden();
            this.close();
            // Trigger change event
            var event = new Event('change', { bubbles: true });
            this.inputEl.dispatchEvent(event);
            if (this.hiddenEl) {
                this.hiddenEl.dispatchEvent(new Event('change', { bubbles: true }));
            }
        },

        _goToday: function () {
            var now = new Date();
            var today = JalaliConverter.gregorianToJalali(now.getFullYear(), now.getMonth() + 1, now.getDate());
            this._selectDay(today[0], today[1], today[2]);
        }
    };

    // ─── Initialize all date pickers ───────────────────────────
    function initPickers() {
        var inputs = document.querySelectorAll('.jalali-datepicker-input');
        for (var i = 0; i < inputs.length; i++) {
            var input = inputs[i];
            if (input._jalaliPickerInitialized) continue;

            var hiddenId = input.getAttribute('data-gregorian-target');
            var hidden = hiddenId ? document.getElementById(hiddenId) : null;

            new JalaliDatePicker(input, hidden);
            input._jalaliPickerInitialized = true;
        }
    }

    // Run on DOM ready
    if (document.readyState === 'loading') {
        document.addEventListener('DOMContentLoaded', initPickers);
    } else {
        initPickers();
    }

})();