/* ==========================================================================
   librus-tui frontend - core: state, helpers, API, chrome
   ========================================================================== */

"use strict";

const $ = (selector, root = document) => root.querySelector(selector);
const $$ = (selector, root = document) => Array.from(root.querySelectorAll(selector));

const VIEWS = ["dashboard", "grades", "timetable", "homework", "attendance", "messages", "freedays"];
const WEEK_ORDER = ["Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday"];
const DAY_NAMES = ["Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday"];

const VIEW_TITLES = {
  dashboard: "dashboard",
  grades: "grades",
  timetable: "timetable",
  homework: "homework & tests",
  attendance: "attendance",
  messages: "messages",
  freedays: "free days",
};

const VIEW_ALIASES = {
  d: "dashboard",
  dash: "dashboard",
  dashboard: "dashboard",
  g: "grades",
  grades: "grades",
  oceny: "grades",
  t: "timetable",
  plan: "timetable",
  timetable: "timetable",
  h: "homework",
  hw: "homework",
  exams: "homework",
  homework: "homework",
  sprawdziany: "homework",
  a: "attendance",
  attendance: "attendance",
  frekwencja: "attendance",
  m: "messages",
  msg: "messages",
  messages: "messages",
  wiadomosci: "messages",
  f: "freedays",
  free: "freedays",
  freedays: "freedays",
  dni: "freedays",
};

const state = {
  config: { demo: false, version: "1.0.0" },
  session: null,
  view: "dashboard",
  loadToken: 0,
  messageToken: 0,
  loginBusy: false,
  timetableWeek: 0,
  gradeFilter: "",
  gradeGroups: [],
  gradesFlat: [],
  exams: [],
  messages: [],
  messageIndex: -1,
  messageCache: new Map(),
  commandHistory: [],
  commandPosition: -1,
  lastSync: null,
};

let spinnerTimer = null;
let bootTimer = null;

/* ------------------------------------------------------------------ helpers */

const HTML_ESCAPES = { "&": "&amp;", "<": "&lt;", ">": "&gt;", '"': "&quot;", "'": "&#39;" };

function esc(value) {
  return String(value ?? "").replace(/[&<>"']/g, (char) => HTML_ESCAPES[char]);
}

function personName(person) {
  if (!person) return "";
  return `${person.FirstName || ""} ${person.LastName || ""}`.trim();
}

function parseDate(value) {
  if (!value) return null;
  const match = String(value).match(/^(\d{4})-(\d{2})-(\d{2})/);
  if (!match) return null;
  const year = Number(match[1]);
  const month = Number(match[2]);
  const day = Number(match[3]);
  if (!year || !month || !day) return null;
  return new Date(year, month - 1, day);
}

function isoDate(date = new 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}`;
}

function fmtDate(value, withYear = true) {
  const date = parseDate(value);
  if (!date) return "—";
  const day = String(date.getDate()).padStart(2, "0");
  const month = String(date.getMonth() + 1).padStart(2, "0");
  return withYear ? `${day}.${month}.${date.getFullYear()}` : `${day}.${month}`;
}

function fmtDateShort(value) {
  return fmtDate(value, false);
}

function weekdayShort(value) {
  const date = parseDate(value);
  if (!date) return "";
  return ["Sun", "Mon", "Tue", "Wed", "Thu", "Fri", "Sat"][date.getDay()];
}

function daysUntil(value) {
  const date = parseDate(value);
  if (!date) return null;
  const today = new Date();
  today.setHours(0, 0, 0, 0);
  date.setHours(0, 0, 0, 0);
  return Math.round((date - today) / 86400000);
}

function countdownLabel(value) {
  const days = daysUntil(value);
  if (days === null) return "";
  if (days === 0) return "today";
  if (days === 1) return "tomorrow";
  if (days === -1) return "yesterday";
  if (days > 1) return `in ${days} days`;
  return `${-days} days ago`;
}

function countdownClass(value) {
  const days = daysUntil(value);
  if (days === 0) return "now";
  if (days !== null && days > 0 && days <= 7) return "soon";
  return "";
}

function shortTime(value) {
  if (!value) return "";
  const match = String(value).match(/^(\d{1,2}):(\d{2})/);
  if (!match) return String(value);
  return `${match[1].padStart(2, "0")}:${match[2]}`;
}

function timeRange(from, to) {
  const start = shortTime(from);
  const end = shortTime(to);
  if (start && end) return `${start}–${end}`;
  return start || end || "—";
}

function timeToMinutes(value) {
  const match = String(value || "").match(/^(\d{1,2}):(\d{2})/);
  if (!match) return null;
  return Number(match[1]) * 60 + Number(match[2]);
}

function truncate(value, length = 90) {
  const text = String(value ?? "");
  if (text.length <= length) return text;
  return `${text.slice(0, Math.max(0, length - 1))}…`;
}

function titleCase(value) {
  const text = String(value ?? "");
  return text ? text.charAt(0).toUpperCase() + text.slice(1) : "";
}

function weightNumber(weight) {
  const number = Number.parseFloat(String(weight ?? "").replace(",", "."));
  return Number.isFinite(number) && number > 0 ? number : 1;
}

function numericGrade(grade) {
  const number = Number.parseFloat(String(grade ?? "").replace(",", "."));
  return Number.isFinite(number) ? number : null;
}

function gradeClass(grade) {
  const number = numericGrade(grade);
  if (number === null) return "g-none";
  if (number >= 5) return "g-excellent";
  if (number >= 4) return "g-good";
  if (number >= 3) return "g-ok";
  return "g-bad";
}

function subjectAverage(grades) {
  let total = 0;
  let weights = 0;
  for (const grade of grades) {
    const value = numericGrade(grade.Grade);
    if (value === null) continue;
    const weight = weightNumber(grade.Weight);
    total += value * weight;
    weights += weight;
  }
  return weights ? total / weights : null;
}

function averageLabel(grades) {
  const average = subjectAverage(grades);
  return average === null ? "—" : average.toFixed(2);
}

function examTagClass(type) {
  const text = String(type || "").toLowerCase();
  if (text.includes("sprawdzian") || text.includes("test")) return "tag-red";
  if (text.includes("kartk") || text.includes("quiz")) return "tag-amber";
  if (text.includes("projekt") || text.includes("wyprac") || text.includes("esej")) return "tag-cyan";
  return "tag-dim";
}

function schoolAddress(school) {
  if (!school) return "—";
  const parts = [school.Street, school.BuildingNumber].filter(Boolean).join(" ");
  const city = [school.PostCode, school.Town].filter(Boolean).join(" ");
  return [parts, city].filter(Boolean).join(", ") || school.Name || "—";
}

function sleep(ms) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

/* ---------------------------------------------------------------------- API */

class ApiError extends Error {
  constructor(message, status = 0) {
    super(message);
    this.name = "ApiError";
    this.status = status;
  }
}

async function api(path, options = {}) {
  const opts = { credentials: "same-origin", ...options };
  if (opts.body && typeof opts.body !== "string") {
    opts.headers = { "Content-Type": "application/json", ...(opts.headers || {}) };
    opts.body = JSON.stringify(opts.body);
  }

  let response;
  try {
    response = await fetch(path, opts);
  } catch (error) {
    throw new ApiError("Network error: cannot reach the librus-tui server.", 0);
  }

  let data = null;
  try {
    data = await response.json();
  } catch (error) {
    data = null;
  }

  if (!response.ok) {
    if (
      response.status === 401 &&
      state.session &&
      state.session.authenticated &&
      !path.startsWith("/api/login")
    ) {
      handleExpiredSession();
    }
    const message = (data && data.error) || `Request failed (HTTP ${response.status}).`;
    throw new ApiError(message, response.status);
  }
  return data;
}

/* ------------------------------------------------------------ chrome helpers */

function setLed(kind) {
  const led = $("#connection-led");
  if (!led) return;
  led.classList.remove("online", "busy", "offline");
  if (kind) led.classList.add(kind);
}

function setStatus(text, kind = "") {
  const element = $("#status-left");
  if (!element) return;
  element.textContent = text;
  element.className = `status-left${kind ? ` ${kind}` : ""}`;
}

function setMeta(text) {
  const element = $("#view-meta");
  if (element) element.textContent = text;
}

function syncTime() {
  return new Date().toLocaleTimeString("en-GB", { hour12: false });
}

function setViewReady(note) {
  stopSpinner();
  setLed("online");
  state.lastSync = new Date();
  const label = note || `loaded ${VIEW_TITLES[state.view] || state.view}`;
  setMeta(`synced ${syncTime()}`);
  setStatus(`[ok] ${label}`, "ok");
  const statusRight = $("#status-right");
  if (statusRight) statusRight.textContent = "synergia://connected";
}

function startSpinner() {
  stopSpinner();
  const frames = "|/-\\";
  let index = 0;
  spinnerTimer = setInterval(() => {
    $$(".spinner").forEach((element) => {
      element.textContent = frames[index % frames.length];
    });
    index += 1;
  }, 110);
}

function stopSpinner() {
  if (spinnerTimer) {
    clearInterval(spinnerTimer);
    spinnerTimer = null;
  }
}

function setViewLoading(label) {
  const view = $("#view");
  if (!view) return;
  view.innerHTML = `<div class="loading"><span class="spinner">|</span> ${esc(label)}</div>`;
  setMeta("contacting synergia…");
  setStatus(`[...] ${label}`);
  setLed("busy");
  startSpinner();
}

function toast(message, kind = "ok", duration = 3800) {
  const root = $("#toasts");
  if (!root) return;
  const element = document.createElement("div");
  element.className = `toast ${kind}`;
  const prefix = document.createElement("span");
  prefix.className = "toast-prefix";
  prefix.textContent = kind === "err" ? "!!" : kind === "warn" ? "!" : ">>";
  element.appendChild(prefix);
  element.appendChild(document.createTextNode(message));
  root.appendChild(element);
  setTimeout(() => {
    element.remove();
  }, duration);
}

/* --------------------------------------------------------------------- modal */

function openModal(title, bodyHtml, actions = []) {
  const root = $("#modal-root");
  const titleElement = $("#modal-title");
  const bodyElement = $("#modal-body");
  const actionsElement = $("#modal-actions");
  if (!root || !titleElement || !bodyElement || !actionsElement) return;

  titleElement.textContent = title;
  bodyElement.innerHTML = bodyHtml;
  actionsElement.innerHTML = "";
  for (const action of actions) {
    const button = document.createElement("button");
    button.type = "button";
    button.className = `btn${action.kind ? ` ${action.kind}` : ""}`;
    button.textContent = action.label;
    if (action.close) {
      button.dataset.modalClose = "";
    } else if (action.action) {
      button.dataset.action = action.action;
    }
    actionsElement.appendChild(button);
  }
  root.classList.remove("hidden");
  const box = $("#modal-box");
  if (box) box.focus();
}

function closeModal() {
  const root = $("#modal-root");
  if (root) root.classList.add("hidden");
}

function openHelpModal() {
  const body = `
    <p><b>librus-tui</b> is a keyboard-first terminal frontend for the Librus Synergia
    student portal. Everything is rendered from the Synergia gateway API.</p>
    <div class="help-section">global keys</div>
    <dl class="help-grid">
      <dt>1 … 7</dt><dd>jump to a section</dd>
      <dt>r</dt><dd>refresh the current section</dd>
      <dt>:</dt><dd>open the command line</dd>
      <dt>?</dt><dd>this help window</dd>
      <dt>q</dt><dd>log out</dd>
      <dt>j / k</dt><dd>scroll, or move through the inbox</dd>
      <dt>g / G</dt><dd>jump to top / bottom</dd>
    </dl>
    <div class="help-section">sections</div>
    <dl class="help-grid">
      <dt>grades</dt><dd><kbd>/</kbd> filter · click a grade for details</dd>
      <dt>timetable</dt><dd><kbd>[</kbd> previous week · <kbd>]</kbd> next week</dd>
      <dt>homework</dt><dd>click a row for the full description</dd>
      <dt>messages</dt><dd><kbd>j</kbd>/<kbd>k</kbd> select · <kbd>Enter</kbd> open · attachments download</dd>
    </dl>
    <div class="help-section">commands</div>
    <dl class="help-grid">
      <dt>:dashboard :grades …</dt><dd>jump to any section (aliases: d, g, t, h, a, m, f)</dd>
      <dt>:week 0..3</dt><dd>select a timetable week</dd>
      <dt>:reload</dt><dd>refresh the current section</dd>
      <dt>:status</dt><dd>print session information</dd>
      <dt>:clear</dt><dd>clear the screen</dd>
      <dt>:fullscreen / :fs</dt><dd>toggle browser fullscreen</dd>
      <dt>:logout</dt><dd>end the Synergia session</dd>
    </dl>
    <div class="help-section">about</div>
    <p>Synergia client adapted from
      <a href="https://github.com/dani3l0/librusik" target="_blank" rel="noopener noreferrer">dani3l0/librusik</a>
      (<code>lib/api/librus.py</code>, stable).<br>
      Your credentials are exchanged directly with Librus and are never written to disk.</p>
  `;
  openModal("help", body, [{ label: "[ close ]", close: true }]);
}

/* ----------------------------------------------------------------- boot log */

function appendBoot(kind, text) {
  const log = $("#bootlog");
  if (!log) return;
  const line = document.createElement("span");
  if (kind) line.className = kind;
  line.textContent = `${text}\n`;
  log.appendChild(line);
  log.scrollTop = log.scrollHeight;
}

function clearBoot() {
  const log = $("#bootlog");
  if (log) log.innerHTML = "";
}

function stopBootTimer() {
  if (bootTimer) {
    clearInterval(bootTimer);
    bootTimer = null;
  }
}

function startBootTimer() {
  stopBootTimer();
  const lines = [
    ["info", "  $ ssh synergia.librus.pl"],
    ["cmd", "  GET  /loguj/portalRodzina"],
    ["cmd", "  POST api.librus.pl/OAuth/Authorization?client_id=46"],
    ["cmd", "  GET  /OAuth/Authorization/2FA?client_id=46"],
    ["cmd", "  waiting for DZIENNIKSID / SDZIENNIKSID …"],
    ["cmd", "  probing /gateway/api/2.0/Auth/TokenInfo …"],
  ];
  let index = 0;
  bootTimer = setInterval(() => {
    if (index < lines.length) {
      appendBoot(lines[index][0], lines[index][1]);
      index += 1;
    } else {
      stopBootTimer();
    }
  }, 360);
}