/* 锚定在日期输入旁的页内日历。不引入第三方库；滚动/缩放后跟随触发器。 */
(function (global) {
  var WEEK = ["日", "一", "二", "三", "四", "五", "六"];
  var panel = null;
  var grid = null;
  var titleEl = null;
  var yearSelect = null;
  var monthSelect = null;
  var activeInput = null;
  var viewYear = 0;
  var viewMonth = 0;
  var bound = false;
  var YEAR_PAD = 80;
  var YEAR_AHEAD = 20;

  function pad(n) {
    return n < 10 ? "0" + n : String(n);
  }

  function toISO(year, month, day) {
    return year + "-" + pad(month + 1) + "-" + pad(day);
  }

  function parseISO(value) {
    var match = /^(\d{4})-(\d{2})-(\d{2})$/.exec(String(value || "").trim());
    if (!match) return null;
    var year = Number(match[1]);
    var month = Number(match[2]) - 1;
    var day = Number(match[3]);
    var date = new Date(year, month, day);
    if (date.getFullYear() !== year || date.getMonth() !== month || date.getDate() !== day) {
      return null;
    }
    return date;
  }

  function todayISO() {
    var now = new Date();
    return toISO(now.getFullYear(), now.getMonth(), now.getDate());
  }

  function ensurePanel() {
    if (panel) return;
    panel = document.createElement("div");
    panel.className = "ds-datepicker";
    panel.id = "ds-datepicker";
    panel.hidden = true;
    panel.setAttribute("role", "dialog");
    panel.setAttribute("aria-label", "选择日期");
    panel.innerHTML =
      '<div class="ds-dp-head">' +
        '<button type="button" class="ds-dp-nav" data-dp-nav="-1" aria-label="上一月">‹</button>' +
        '<div class="ds-dp-title">' +
          '<select class="select ds-dp-ym" data-dp-year aria-label="年份"></select>' +
          '<select class="select ds-dp-ym" data-dp-month aria-label="月份"></select>' +
        "</div>" +
        '<button type="button" class="ds-dp-nav" data-dp-nav="1" aria-label="下一月">›</button>' +
      "</div>" +
      '<div class="ds-dp-week">' + WEEK.map(function (d) { return "<span>" + d + "</span>"; }).join("") + "</div>" +
      '<div class="ds-dp-grid" role="grid"></div>' +
      '<div class="ds-dp-foot">' +
        '<button type="button" data-dp-today>今天</button>' +
        '<button type="button" data-dp-clear>清除</button>' +
      "</div>";
    document.body.appendChild(panel);
    titleEl = panel.querySelector(".ds-dp-title");
    yearSelect = panel.querySelector("[data-dp-year]");
    monthSelect = panel.querySelector("[data-dp-month]");
    grid = panel.querySelector(".ds-dp-grid");
    yearSelect.addEventListener("change", function () {
      var next = Number(yearSelect.value);
      if (!next) return;
      viewYear = next;
      render();
    });
    monthSelect.addEventListener("change", function () {
      var next = Number(monthSelect.value);
      if (Number.isNaN(next)) return;
      viewMonth = next;
      render();
    });
    panel.addEventListener("mousedown", function (event) {
      if (event.target.closest(".ds-combo, select, input, textarea")) return;
      event.preventDefault();
    });
    panel.addEventListener("click", function (event) {
      if (event.target.closest(".ds-combo, .ds-listbox, select")) return;
      var nav = event.target.closest("[data-dp-nav]");
      if (nav) {
        shiftMonth(Number(nav.getAttribute("data-dp-nav")));
        return;
      }
      if (event.target.closest("[data-dp-today]")) {
        commit(todayISO());
        return;
      }
      if (event.target.closest("[data-dp-clear]")) {
        commit("");
        return;
      }
      var dayBtn = event.target.closest("[data-iso]");
      if (dayBtn && !dayBtn.disabled) commit(dayBtn.getAttribute("data-iso"));
    });
  }

  function enhance(input) {
    if (!input || input.dataset.dsDate === "1") return;
    input.dataset.dsDate = "1";
    if (input.type === "date") {
      var value = input.value;
      try {
        input.type = "text";
      } catch (err) {
        /* keep native type if the engine refuses */
      }
      if (value) input.value = value;
    }
    input.setAttribute("inputmode", "numeric");
    input.setAttribute("autocomplete", "off");
    input.setAttribute("spellcheck", "false");
    input.setAttribute("placeholder", input.getAttribute("placeholder") || "YYYY-MM-DD");
    if (!input.getAttribute("pattern")) input.setAttribute("pattern", "\\d{4}-\\d{2}-\\d{2}");
    if (!input.classList.contains("num-input")) input.classList.add("num-input");
    input.setAttribute("aria-haspopup", "dialog");
  }

  function scan() {
    document.querySelectorAll('input[type="date"]').forEach(enhance);
  }

  function boundYears() {
    var now = new Date().getFullYear();
    var minY = now - YEAR_PAD;
    var maxY = now + YEAR_AHEAD;
    var hasMin = false;
    var hasMax = false;
    if (activeInput && activeInput.min) {
      var minDate = parseISO(activeInput.min);
      if (minDate) {
        minY = minDate.getFullYear();
        hasMin = true;
      }
    }
    if (activeInput && activeInput.max) {
      var maxDate = parseISO(activeInput.max);
      if (maxDate) {
        maxY = maxDate.getFullYear();
        hasMax = true;
      }
    }
    if (!hasMin && viewYear < minY) minY = viewYear;
    if (!hasMax && viewYear > maxY) maxY = viewYear;
    if (hasMin && viewYear < minY) minY = viewYear;
    if (hasMax && viewYear > maxY) maxY = viewYear;
    return { minY: minY, maxY: maxY };
  }

  function lastDayOfMonth(year, month) {
    return new Date(year, month + 1, 0).getDate();
  }

  function monthHasValidDay(year, month) {
    var min = activeInput && activeInput.min ? activeInput.min : "";
    var max = activeInput && activeInput.max ? activeInput.max : "";
    var start = toISO(year, month, 1);
    var end = toISO(year, month, lastDayOfMonth(year, month));
    if (min && end < min) return false;
    if (max && start > max) return false;
    return true;
  }

  function syncYearMonthSelects() {
    if (!yearSelect || !monthSelect) return;
    var years = boundYears();
    var yearHtml = "";
    for (var year = years.minY; year <= years.maxY; year += 1) {
      yearHtml += '<option value="' + year + '"' + (year === viewYear ? " selected" : "") + ">" + year + "年</option>";
    }
    yearSelect.innerHTML = yearHtml;
    yearSelect.value = String(viewYear);
    var monthHtml = "";
    for (var month = 0; month < 12; month += 1) {
      var disabled = !monthHasValidDay(viewYear, month);
      monthHtml +=
        '<option value="' + month + '"' +
        (month === viewMonth ? " selected" : "") +
        (disabled ? " disabled" : "") +
        ">" + pad(month + 1) + "月</option>";
    }
    monthSelect.innerHTML = monthHtml;
    monthSelect.value = String(viewMonth);
    if (global.JinniuSelect && typeof global.JinniuSelect.scan === "function") {
      global.JinniuSelect.scan(panel);
    }
  }

  function render() {
    if (!grid || !titleEl) return;
    syncYearMonthSelects();
    var first = new Date(viewYear, viewMonth, 1);
    var start = first.getDay();
    var selected = activeInput ? parseISO(activeInput.value) : null;
    var selectedISO = selected ? toISO(selected.getFullYear(), selected.getMonth(), selected.getDate()) : "";
    var today = todayISO();
    var min = activeInput && activeInput.min ? activeInput.min : "";
    var max = activeInput && activeInput.max ? activeInput.max : "";
    var html = "";
    var cursor = new Date(viewYear, viewMonth, 1 - start);
    for (var i = 0; i < 42; i += 1) {
      var iso = toISO(cursor.getFullYear(), cursor.getMonth(), cursor.getDate());
      var other = cursor.getMonth() !== viewMonth;
      var disabled = (min && iso < min) || (max && iso > max);
      var cls = "ds-dp-day";
      if (other) cls += " is-other";
      if (iso === today) cls += " is-today";
      if (iso === selectedISO) cls += " is-selected";
      html +=
        '<button type="button" class="' + cls + '" data-iso="' + iso + '"' +
        (disabled ? " disabled" : "") +
        ' aria-label="' + iso + '"' +
        (iso === selectedISO ? ' aria-current="date"' : "") +
        ">" + cursor.getDate() + "</button>";
      cursor.setDate(cursor.getDate() + 1);
    }
    grid.innerHTML = html;
    position();
  }

  function viewportBox() {
    var vv = global.visualViewport;
    if (vv) {
      return {
        left: vv.offsetLeft,
        top: vv.offsetTop,
        width: vv.width,
        height: vv.height,
      };
    }
    return { left: 0, top: 0, width: global.innerWidth, height: global.innerHeight };
  }

  function position() {
    if (!panel || panel.hidden || !activeInput) return;
    var rect = activeInput.getBoundingClientRect();
    var view = viewportBox();
    var gap = 6;
    var width = panel.offsetWidth || 280;
    var height = panel.offsetHeight || 320;
    var left = rect.left;
    var top = rect.bottom + gap;
    if (top + height > view.top + view.height - 8 && rect.top - gap - height >= view.top + 8) {
      top = rect.top - gap - height;
    }
    if (left + width > view.left + view.width - 8) {
      left = Math.max(view.left + 8, rect.right - width);
    }
    if (left < view.left + 8) left = view.left + 8;
    if (top < view.top + 8) top = view.top + 8;
    panel.style.left = Math.round(left) + "px";
    panel.style.top = Math.round(top) + "px";
  }

  function openPicker(input) {
    if (!input || input.disabled) return;
    enhance(input);
    ensurePanel();
    activeInput = input;
    var parsed = parseISO(input.value) || new Date();
    viewYear = parsed.getFullYear();
    viewMonth = parsed.getMonth();
    panel.hidden = false;
    render();
    input.setAttribute("aria-expanded", "true");
  }

  function closePicker() {
    if (!panel || panel.hidden) return;
    if (global.JinniuSelect && typeof global.JinniuSelect.close === "function") {
      global.JinniuSelect.close();
    }
    panel.hidden = true;
    if (activeInput) activeInput.setAttribute("aria-expanded", "false");
    activeInput = null;
  }

  function shiftMonth(delta) {
    viewMonth += delta;
    while (viewMonth < 0) {
      viewMonth += 12;
      viewYear -= 1;
    }
    while (viewMonth > 11) {
      viewMonth -= 12;
      viewYear += 1;
    }
    render();
  }

  function commit(iso) {
    if (!activeInput) return;
    var input = activeInput;
    input.value = iso;
    input.dispatchEvent(new Event("input", { bubbles: true }));
    input.dispatchEvent(new Event("change", { bubbles: true }));
    closePicker();
    input.focus({ preventScroll: true });
  }

  function onPointer(event) {
    var input = event.target.closest && event.target.closest('input[type="date"], input[data-ds-date="1"]');
    if (input) {
      if (event.type === "mousedown" && event.button === 0) event.preventDefault();
      openPicker(input);
      return;
    }
    if (
      panel &&
      !panel.hidden &&
      !panel.contains(event.target) &&
      !(event.target.closest && event.target.closest(".ds-listbox"))
    ) {
      closePicker();
    }
  }

  function onKey(event) {
    if (event.key === "Escape") {
      closePicker();
      return;
    }
    var input = event.target.closest && event.target.closest('input[data-ds-date="1"]');
    if (!input) return;
    if (event.key === "ArrowDown" || event.key === "Enter" || event.key === " ") {
      event.preventDefault();
      openPicker(input);
    }
  }

  function bind() {
    if (bound) return;
    bound = true;
    document.addEventListener("mousedown", onPointer, true);
    document.addEventListener("focusin", function (event) {
      var input = event.target.closest && event.target.closest('input[type="date"]');
      if (input) openPicker(input);
    });
    document.addEventListener("keydown", onKey);
    document.addEventListener("scroll", position, true);
    global.addEventListener("resize", position);
    if (global.visualViewport) {
      global.visualViewport.addEventListener("resize", position);
      global.visualViewport.addEventListener("scroll", position);
    }
    if (typeof MutationObserver === "function") {
      new MutationObserver(scan).observe(document.documentElement, { childList: true, subtree: true });
    }
    scan();
  }

  if (document.readyState === "loading") {
    document.addEventListener("DOMContentLoaded", bind);
  } else {
    bind();
  }

  global.JinniuDatePicker = { open: openPicker, close: closePicker, scan: scan };
})(window);