/* =============================================================================
 * ui_template_help.ts
 * [?] 사용자 가이드(54-2 · 538) — 좌측 패널 아래 단추 묶음 맨 왼쪽 단추 + 넓은 모달(왼쪽 차례 · 오른쪽 가이드 통째).
 * 글 = `A05_EduDetail/guide/<페이지>/*.md` — 서버가 열 때마다 읽음(`GET /api/help` 한 번에 모든 페이지).
 * 차례 = 묶음(임도 설계 B → 안정성평가 E → 예정노선 D) → 페이지 → 기능 · 지금 페이지 펼침.
 * 처음 자리 = 좌측 패널에서 보이는 `[data-help-topic]` 중 마지막 절(제 페이지 먼저 · 없으면 모든 페이지) ·
 * 없으면 지금 페이지(#/b05-… → B05) 절 · 그것도 없으면 맨 앞.
 * 시스템 관리자 = 더블클릭 바로 고침(`ui_template_help_edit.ts`).
 * 단추 자리 = `.ui-sidebar-actions` 안 `[data-help-row]`(없으면 그 줄 자신)의 맨 앞.
 * [<] [>](요구 280-2) = [?] 바로 뒤 · 단계 묶음(B05~B09 · D02~D04 · E02~E05 · 529-1) 주소만 · 누르면 `ui-step-nav` 를 올려 보냄 →
 * 진행 단계 틀(`createWorkflowLayout`)이 이웃 단계 단추를 누름(저장 · 막힘은 각 페이지 `onStepClick`).
 * ========================================================================== */

import "./ui_template_help.css";
import { API_BASE_URL, PLAN_STEP_ROUTES, ROUTES, STAB_STEP_ROUTES } from "@config/config_frontend";
import { createButton, el } from "./ui_template_elements";
import { attachHelpEditing } from "./ui_template_help_edit";
import { openModal } from "./ui_template_modal";

export interface HelpItem {
  key: string;
  title: string;
  text: string;
  version: string;
}

export interface HelpPage {
  page: string;
  title: string;
  items: HelpItem[];
  /** 그림 이름 → 판(고친 시각) */
  images: Record<string, string>;
}

export interface HelpGuide {
  pages: HelpPage[];
  admin: boolean;
}

const TEXT = {
  button: "?",
  tip: "사용자 가이드",
  title: "사용자 가이드",
  close: "닫기",
  empty: "가이드 글 없음",
  imgMissing: "그림 없음 — 더블클릭해 지정",
  imgPending: "그림 준비 중",
};
const STEP_TEXT = { prev: "<", next: ">", prevTip: "이전 단계", nextTip: "다음 단계" };
/** 차례 묶음 — 페이지 머리 글자 */
const GROUPS = [
  { label: "임도 설계", prefix: "B" },
  { label: "안정성평가", prefix: "E" },
  { label: "예정노선", prefix: "D" },
];
const IMG_RE = /^[A-Za-z0-9_-]+\.(webp|png|jpg)$/;

/** [<] [>] 를 붙이는 주소 묶음 — 묶음 안에서만 오감(b09-print · B03 · B04 · M01 · M02 · D01 · E01 뺌) */
const STEP_NAV_GROUPS: ReadonlyArray<readonly string[]> = [
  [
    ROUTES.B05_PROFILE,
    ROUTES.B06_SECTION,
    ROUTES.B07_DESIGN_DETAIL,
    ROUTES.B08_QUANTITY,
    ROUTES.B09_ESTIMATION,
  ],
  PLAN_STEP_ROUTES,
  STAB_STEP_ROUTES,
];

/** 가이드 폴더 이름 = 주소 머리(#/b05-… → B05 · #/d02-… → D02) */
function currentPage(): string {
  const head = /^#\/([bde]0\d)/i.exec(location.hash)?.[1];
  return head ? head.toUpperCase() : "";
}

function escapeHtml(text: string): string {
  return text.replace(
    /[&<>"]/g,
    (c) => `&${{ "&": "amp", "<": "lt", ">": "gt", '"': "quot" }[c]};`,
  );
}

/** 가이드 안 링크 `[글](B06/00_설명서)` · `[글](B06)` — 파일 이름 속 괄호 한 겹까지 */
const GOTO_RE = /\[([^\]]+)\]\(([BDE]\d{2}(?:\/(?:[^()]|\([^()]*\))+)?)\)/g;

function inline(text: string, links = false): string {
  const html = escapeHtml(text)
    .replace(/\*\*(.+?)\*\*/g, "<strong>$1</strong>")
    .replace(/`(.+?)`/g, "<code>$1</code>");
  return links
    ? html.replace(GOTO_RE, '<a href="#" class="ui-help-goto" data-help-goto="$2">$1</a>')
    : html;
}

/** 페이지를 넘긴 때만 — 덩어리 원문 줄(`data-src`) · 그림 · 주의/참고 상자 · 가이드 안 링크 */
export interface HelpRenderContext {
  page: string;
  images: Record<string, string>;
  admin: boolean;
}

function figure(alt: string, name: string, ctx: HelpRenderContext): string {
  const version = ctx.images[name];
  const img = version
    ? `<img src="${API_BASE_URL}/help/${ctx.page}/img/${name}?v=${version}" alt="${escapeHtml(alt)}" loading="lazy">`
    : `<div class="ui-help-figure__empty">${ctx.admin ? TEXT.imgMissing : TEXT.imgPending}</div>`;
  const caption = alt ? `<figcaption>${inline(alt)}</figcaption>` : "";
  return `<figure class="ui-help-figure" data-img="${name}">${img}${caption}</figure>`;
}

function note(lines: string[], src: string): string {
  const body = lines.map((line) => line.replace(/^>\s?/, ""));
  const head = /^(주의|참고)\s*[:：]\s*(.*)$/.exec(body[0]);
  if (head) body[0] = head[2];
  const kind = head?.[1] === "주의" ? "warn" : "info";
  return `<aside class="ui-help-note ui-help-note--${kind}"${src}><strong>${head?.[1] ?? "참고"}</strong> ${body.map((line) => inline(line, true)).join("<br>")}</aside>`;
}

/** 메모장 글에 쓸 만큼만 — 제목(#) · 목록(- · 1.) · 표 · 문단 · **굵게** · `코드` (+ ctx 때 그림 · 상자 · 링크) */
export function renderHelpMarkdown(text: string, ctx?: HelpRenderContext): string {
  const out: string[] = [];
  let list: "ul" | "ol" | null = null;
  let para: string[] = [];
  let start = 0;
  let end = 0;
  let listAt = 0;
  let listFrom = 0;
  const lines = text.split(/\r?\n/);
  const src = (from: number, to: number): string => (ctx ? ` data-src="${from}-${to}"` : "");
  const cells = (line: string): string[] =>
    line
      .trim()
      .replace(/^\||\|$/g, "")
      .split("|")
      .map((cell) => cell.trim());
  const separator = (line: string): boolean =>
    cells(line).every((cell) => /^:?-{3,}:?$/.test(cell));
  const flush = (): void => {
    if (para.length)
      out.push(`<p${src(start, end)}>${para.map((l) => inline(l, !!ctx)).join("<br>")}</p>`);
    para = [];
    if (list) out.push(`</${list}>`);
    list = null;
  };
  for (let index = 0; index < lines.length; index += 1) {
    const raw = lines[index];
    const line = raw.trim();
    if (line.includes("|") && lines[index + 1]?.includes("|") && separator(lines[index + 1])) {
      flush();
      const from = index;
      const headers = cells(line);
      const rows: string[][] = [];
      index += 2;
      while (index < lines.length && lines[index].includes("|")) rows.push(cells(lines[index++]));
      index -= 1;
      out.push(
        `<div class="ui-markdown-table"${src(from, index)}><table><thead><tr>${headers.map((cell) => `<th>${inline(cell, !!ctx)}</th>`).join("")}</tr></thead><tbody>${rows.map((row) => `<tr>${headers.map((_, cell) => `<td>${inline(row[cell] ?? "", !!ctx)}</td>`).join("")}</tr>`).join("")}</tbody></table></div>`,
      );
      continue;
    }
    const head = /^(#{1,4})\s+(.*)$/.exec(line);
    const item = /^(?:([-*])|\d+\.)\s+(.*)$/.exec(line);
    const image = ctx && /^!\[([^\]]*)\]\(([^)\s]+)\)$/.exec(line);
    if (!line) flush();
    else if (ctx && line.startsWith(">")) {
      flush();
      const from = index;
      while (lines[index + 1]?.trim().startsWith(">")) index += 1;
      const quote = lines.slice(from, index + 1).map((l) => l.trim());
      out.push(note(quote, src(from, index)));
    } else if (image && IMG_RE.test(image[2])) {
      flush();
      out.push(figure(image[1], image[2], ctx).replace("<figure", `<figure${src(index, index)}`));
    } else if (head) {
      flush();
      const level = head[1].length + 1;
      out.push(`<h${level}${src(index, index)}>${inline(head[2], !!ctx)}</h${level}>`);
    } else if (item) {
      const kind = item[1] ? "ul" : "ol";
      if (para.length || list !== kind) flush();
      if (!list) {
        listAt = out.length;
        listFrom = index;
        out.push("");
      }
      list = kind;
      out.push(`<li>${inline(item[2], !!ctx)}</li>`);
      out[listAt] = `<${kind}${src(listFrom, index)}>`;
    } else {
      if (list) flush();
      if (!para.length) start = index;
      end = index;
      para.push(line);
    }
  }
  flush();
  return out.join("");
}

function visibleTopics(): string[] {
  const panel = document.querySelector(".ui-workflow-overlay__panel--title") ?? document;
  return [...panel.querySelectorAll<HTMLElement>("[data-help-topic]")]
    .filter((node) => node.offsetParent !== null)
    .map((node) => node.dataset.helpTopic ?? "");
}

async function fetchGuide(): Promise<HelpGuide> {
  const response = await fetch(`${API_BASE_URL}/help`, {
    credentials: "include",
    cache: "no-store",
  });
  return response.ok ? ((await response.json()) as HelpGuide) : { pages: [], admin: false };
}

/** 한 기능 절 — 자리 이름 `B05/00_설명서` */
export function renderHelpItem(page: HelpPage, item: HelpItem, admin: boolean): string {
  const ctx = { page: page.page, images: page.images, admin };
  return renderHelpMarkdown(item.text, ctx);
}

function anchorOf(page: string, key?: string): string {
  return key ? `${page}/${key}` : page;
}

/** 처음 자리 — 보이는 주제(제 페이지 먼저 · 없으면 모든 페이지) → 지금 페이지 → 맨 앞 */
function firstAnchor(pages: HelpPage[]): string {
  const page = currentPage();
  const topics = visibleTopics().reverse();
  const own = pages.find((p) => p.page === page);
  for (const scope of own ? [[own], pages] : [pages])
    for (const key of topics) {
      const hit = scope.find((p) => p.items.some((item) => item.key === key));
      if (hit) return anchorOf(hit.page, key);
    }
  return own ? page : (pages[0]?.page ?? "");
}

async function openHelp(): Promise<void> {
  const guide = await fetchGuide();
  const pages = GROUPS.flatMap((g) => guide.pages.filter((p) => p.page.startsWith(g.prefix)));
  const start = firstAnchor(pages);
  let flush = async (): Promise<boolean> => true;
  openModal({
    title: TEXT.title,
    closeLabel: TEXT.close,
    dialogClass: "ui-help",
    wide: true,
    beforeClose: () => flush(),
    mount: (body) => {
      const article = el("article", { className: "ui-help__text" });
      const toc = el("nav", { className: "ui-help__toc" });
      const tocPage = new Map<string, HTMLElement>();
      const goTo = (anchor: string): void => {
        const page = anchor.split("/")[0];
        const target = article.querySelector<HTMLElement>(
          `[data-help-anchor="${CSS.escape(anchor)}"]`,
        );
        target?.scrollIntoView({ block: "start" });
        tocPage.forEach((box, key) => box.classList.toggle("is-open", key === page));
        toc
          .querySelectorAll<HTMLElement>("[data-help-goto]")
          .forEach((b) => b.classList.toggle("is-active", b.dataset.helpGoto === anchor));
      };
      const link = (text: string, anchor: string, className: string): HTMLButtonElement => {
        const button = el("button", { className, text, attrs: { type: "button" } });
        button.dataset.helpGoto = anchor;
        button.addEventListener("click", () => goTo(anchor));
        return button;
      };
      for (const group of GROUPS) {
        const own = pages.filter((p) => p.page.startsWith(group.prefix));
        if (!own.length) continue;
        toc.append(el("p", { className: "ui-help__group", text: group.label }));
        for (const page of own) {
          const subs = page.items
            .filter((item) => item.key !== "00_설명서")
            .map((item) => link(item.title, anchorOf(page.page, item.key), "ui-help__link--sub"));
          const box = el("div", {
            className: "ui-help__toc-page",
            children: [
              link(page.title, page.page, "ui-help__link"),
              el("div", { className: "ui-help__subs", children: subs }),
            ],
          });
          tocPage.set(page.page, box);
          toc.append(box);
        }
      }
      for (const page of pages) {
        const section = el("section", { className: "ui-help__page" });
        section.dataset.helpAnchor = page.page;
        for (const item of page.items) {
          const part = el("section", { className: "ui-help__item" });
          part.dataset.helpAnchor = anchorOf(page.page, item.key);
          part.dataset.page = page.page;
          part.dataset.key = item.key;
          part.innerHTML = renderHelpItem(page, item, guide.admin);
          section.append(part);
        }
        article.append(section);
      }
      if (!pages.length) article.append(el("p", { text: TEXT.empty }));
      article.addEventListener("click", (ev) => {
        const goto = (ev.target as HTMLElement).closest<HTMLElement>("a.ui-help-goto");
        if (!goto) return;
        ev.preventDefault();
        goTo(goto.dataset.helpGoto ?? "");
      });
      if (guide.admin)
        flush = attachHelpEditing(article, pages, (page, item) =>
          renderHelpItem(page, item, true),
        ).flush;
      body.append(el("div", { className: "ui-help__grid", children: [toc, article] }));
      // 모달이 붙은 뒤 이동 — mount 는 붙기 전
      requestAnimationFrame(() => goTo(start));
    },
  });
}

export function createHelpButton(): HTMLButtonElement {
  const button = createButton({
    label: TEXT.button,
    variant: "ghost",
    onClick: () => void openHelp(),
  });
  button.classList.add("ui-help-btn");
  button.title = button.ariaLabel = TEXT.tip;
  return button;
}

function createStepNavButton(step: -1 | 1): HTMLButtonElement {
  const button = createButton({
    label: step < 0 ? STEP_TEXT.prev : STEP_TEXT.next,
    variant: "ghost",
    onClick: () =>
      button.dispatchEvent(new CustomEvent("ui-step-nav", { bubbles: true, detail: step })),
  });
  button.classList.add("ui-step-nav-btn");
  button.dataset.stepNav = String(step);
  button.title = button.ariaLabel = step < 0 ? STEP_TEXT.prevTip : STEP_TEXT.nextTip;
  return button;
}

/** 지금 주소의 묶음 · [<] [>] 차례 — 목록 밖이면 차례 -1 */
function stepNavIndex(): { index: number; last: number } {
  const route = location.hash.replace(/^#\/?/, "").split("?")[0];
  const group = STEP_NAV_GROUPS.find((routes) => routes.includes(route)) ?? [];
  return { index: group.indexOf(route), last: group.length - 1 };
}

/** 아래 단추 묶음에 [?] 를 한 번 — `[data-help-row]` 가 있으면 그 줄 · 없으면 묶음 자신의 맨 앞 */
export function placeHelpButton(actions: HTMLElement): void {
  if (actions.querySelector(".ui-help-btn")) return;
  const row = actions.querySelector<HTMLElement>("[data-help-row]") ?? actions;
  if (stepNavIndex().index < 0) return void row.prepend(createHelpButton());
  const prev = createStepNavButton(-1);
  const next = createStepNavButton(1);
  // 첫 단계(B05) [<] · 마지막 단계(B09) [>] 흐림 — B05 ↔ B06 은 페이지를 다시 안 세우므로 주소마다 다시 맞춤
  const sync = (): void => {
    const { index, last } = stepNavIndex();
    prev.disabled = index <= 0;
    next.disabled = index === last;
  };
  const onHash = (): void => {
    if (prev.isConnected) sync();
    else window.removeEventListener("hashchange", onHash); // 화면에서 빠짐 — 풂
  };
  sync();
  window.addEventListener("hashchange", onHash);
  row.prepend(createHelpButton(), prev, next);
}