/* ==========================================================================
   librus-tui frontend - timetable view
   ========================================================================== */

"use strict";

async function renderTimetable(token) {
  const data = await api(`/api/timetable?week=${state.timetableWeek}`);
  if (token !== state.loadToken) return;

  const timetable = data.Timetable || {};
  const weekStart = parseDate(data.weekStart) || mondayOfCurrentWeek(state.timetableWeek);
  const weekEnd = parseDate(data.weekEnd) || addDays(weekStart, 6);
  const weekStartIso = isoDate(weekStart);
  const weekEndIso = isoDate(weekEnd);

  const columns = WEEK_ORDER.filter(
    (day, index) => index < 5 || (timetable[day] || []).length > 0
  );

  const numericLessons = [];
  let hasExtra = false;
  for (const day of columns) {
    for (const entry of timetable[day] || []) {
      const raw = String(entry.Lesson ?? "");
      if (/^\d+$/.test(raw)) {
        numericLessons.push(Number(raw));
      } else {
        hasExtra = true;
      }
    }
  }
  const maxLesson = Math.max(8, ...numericLessons);
  const rows = [];
  for (let number = 1; number <= maxLesson; number += 1) rows.push(String(number));
  if (hasExtra) rows.push("extra");

  const grid = {};
  for (const day of columns) {
    grid[day] = new Map();
    for (const entry of timetable[day] || []) {
      const raw = String(entry.Lesson ?? "");
      const key = /^\d+$/.test(raw) ? raw : "extra";
      if (!grid[day].has(key)) grid[day].set(key, []);
      grid[day].get(key).push(entry);
    }
  }

  const today = isoDate();
  const weekLabel =
    state.timetableWeek === 0
      ? "current week"
      : state.timetableWeek === 1
        ? "next week"
        : `week +${state.timetableWeek}`;

  const header = columns
    .map((day) => {
      const index = WEEK_ORDER.indexOf(day);
      const date = addDays(weekStart, index);
      const dateIso = isoDate(date);
      return `
        <div class="tt-head ${dateIso === today ? "today" : ""}">
          <span>${esc(day.slice(0, 3))}</span>
          <span class="date">${esc(fmtDate(dateIso, false))}</span>
        </div>`;
    })
    .join("");

  const body = rows
    .map((row) => {
      let timeLabel = "";
      if (row !== "extra") {
        for (const day of columns) {
          const entry = (grid[day].get(row) || [])[0];
          if (entry && entry.HourFrom) {
            timeLabel = shortTime(entry.HourFrom);
            break;
          }
        }
      } else {
        for (const day of columns) {
          const entry = (grid[day].get("extra") || [])[0];
          if (entry && entry.HourFrom) {
            timeLabel = shortTime(entry.HourFrom);
            break;
          }
        }
      }

      const hourCell = `
        <div class="tt-hour">
          <b>${row === "extra" ? "+" : esc(row)}</b>
          <span>${esc(timeLabel)}</span>
        </div>`;

      const cells = columns
        .map((day) => {
          const entries = grid[day].get(row) || [];
          if (!entries.length) {
            return `<div class="tt-cell"><div class="tt-free">·</div></div>`;
          }
          return `<div class="tt-cell">${entries.map(renderTimetableEntry).join("")}</div>`;
        })
        .join("");

      return hourCell + cells;
    })
    .join("");

  $("#view").innerHTML = `
    <div class="view-inner">
      <div class="toolbar">
        <button class="btn btn-sm" type="button" data-action="tt-prev" ${state.timetableWeek <= 0 ? "disabled" : ""}>[ &lt; prev ]</button>
        <button class="btn btn-sm" type="button" data-action="tt-next" ${state.timetableWeek >= 3 ? "disabled" : ""}>[ next &gt; ]</button>
        <span><b>${esc(weekLabel)}</b></span>
        <span class="dim">${esc(fmtDate(weekStartIso))} → ${esc(fmtDate(weekEndIso))}</span>
        <span class="grow"></span>
        <span class="dim"><kbd>[</kbd> <kbd>]</kbd> switch week</span>
      </div>
      <div class="timetable-scroll">
        <div class="timetable" style="grid-template-columns: 60px repeat(${columns.length}, minmax(150px, 1fr))">
          <div class="tt-hour corner">lesson</div>
          ${header}
          ${body}
        </div>
      </div>
      <div class="toolbar" style="margin-top:10px">
        <span class="dim">
          <span class="tag tag-amber">SUB</span> substitution ·
          <span class="tag tag-red">CNL</span> cancelled ·
          <span class="tag tag-cyan">EXTRA</span> additional activity
        </span>
      </div>
    </div>
  `;
}

function renderTimetableEntry(entry) {
  const flags = [];
  if (entry.isSubstitution) flags.push(`<span class="tt-flag sub">SUB</span>`);
  if (entry.isCancelled) flags.push(`<span class="tt-flag cancel">CNL</span>`);
  if (entry.isAdditional) flags.push(`<span class="tt-flag extra">EXTRA</span>`);

  const teacher = personName(entry.Teacher);
  const title = [
    entry.Subject,
    timeRange(entry.HourFrom, entry.HourTo),
    entry.Classroom ? `room ${entry.Classroom}` : "",
    teacher,
  ]
    .filter(Boolean)
    .join(" · ");

  return `
    <div class="tt-lesson ${entry.isCancelled ? "cancelled" : ""}" title="${esc(title)}">
      <span class="tt-subject">${esc(entry.Subject || "lesson")}</span>
      <span class="tt-meta">${esc(timeRange(entry.HourFrom, entry.HourTo))}</span>
      <span class="tt-meta"><span class="tt-room">${esc(entry.Classroom || "?")}</span>${teacher ? ` · ${esc(teacher)}` : ""}</span>
      ${flags.length ? `<span class="tt-flags">${flags.join("")}</span>` : ""}
    </div>`;
}

function mondayOfCurrentWeek(week = 0) {
  const today = new Date();
  const monday = addDays(today, -((today.getDay() + 6) % 7) + week * 7);
  monday.setHours(0, 0, 0, 0);
  return monday;
}

function addDays(date, days) {
  const copy = new Date(date.getTime());
  copy.setDate(copy.getDate() + days);
  return copy;
}

function changeTimetableWeek(delta) {
  const next = Math.min(3, Math.max(0, state.timetableWeek + delta));
  if (next === state.timetableWeek) return;
  state.timetableWeek = next;
  navigate("timetable");
}