/**
 * 详情页伪静态风格的单一事实源：
 * middleware（改写/301）、URL 构造器、后台设置、测试共用本模块。
 * 风格枚举与后端 service.UrlStyles 保持一致：default / html / discuz。
 *
 * 各风格模板（自建页 slug、排行榜与书库也参与；slug 非 ASCII 时按 encodeURIComponent 编码）：
 *   default: /post/123  /u/5  /announcement/1  /p/about  /leaderboard  /library  /library/{slug}  /library/{slug}/read?c={书内章号}
 *   html:    /post-123.html  /user-5.html  /announcement-1.html  /p-about.html  /leaderboard.html  /library.html  /library-{slug}.html  （章节：/library-{slug}.html?sec={书内章号}）
 *   discuz:  /thread-123.html  /space-uid-5.html  /notice-1.html  /page-about.html  /rank.html  （书库两风格同 html 模板）
 * 书库章节走详情路径 + ?sec= 查询参数（章内子目录锚点 #e-{sec}-{章内序号}）；旧版 -read-{n} 路径
 * 不再生成，但正则保留可解析（middleware 改写回标准读页），旧链接不失效。
 */

export type UrlStyle = "default" | "html" | "discuz";
export type EntityKind = "post" | "user" | "announcement";
/** 全部可反解的实体类型；page/libraryDoc/libraryRead 的 id 是 slug（字符串），leaderboard/library 是固定单页无 id */
export type PageKind = EntityKind | "page" | "leaderboard" | "library" | "libraryDoc" | "libraryRead";

export const URL_STYLES: readonly UrlStyle[] = ["default", "html", "discuz"];

export function normalizeUrlStyle(v: unknown): UrlStyle {
  const s = String(v ?? "").trim().toLowerCase();
  return (URL_STYLES as readonly string[]).includes(s) ? (s as UrlStyle) : "default";
}

const PRETTY_TEMPLATES: Record<Exclude<UrlStyle, "default">, Record<EntityKind, (id: number) => string>> = {
  html: {
    post: (id) => `/post-${id}.html`,
    user: (id) => `/user-${id}.html`,
    announcement: (id) => `/announcement-${id}.html`,
  },
  discuz: {
    post: (id) => `/thread-${id}.html`,
    user: (id) => `/space-uid-${id}.html`,
    announcement: (id) => `/notice-${id}.html`,
  },
};

const STANDARD_TEMPLATES: Record<EntityKind, (id: number) => string> = {
  post: (id) => `/post/${id}`,
  user: (id) => `/u/${id}`,
  announcement: (id) => `/announcement/${id}`,
};

const PAGE_TEMPLATES: Record<Exclude<UrlStyle, "default">, (slug: string) => string> = {
  html: (slug) => `/p-${slug}.html`,
  discuz: (slug) => `/page-${slug}.html`,
};

const LEADERBOARD_TEMPLATES: Record<Exclude<UrlStyle, "default">, string> = {
  html: "/leaderboard.html",
  discuz: "/rank.html",
};

/** 书库伪静态模板：两风格统一（书库非 Discuz 原生概念）；章节在详情路径上追加 ?sec= */
const LIBRARY_TEMPLATES: Record<Exclude<UrlStyle, "default">, { list: string; doc: (slug: string) => string }> = {
  html: {
    list: "/library.html",
    doc: (slug) => `/library-${slug}.html`,
  },
  discuz: {
    list: "/library.html",
    doc: (slug) => `/library-${slug}.html`,
  },
};

/** id 非法（≤0/非有限数）时返回空串，调用方按异常路径处理 */
function guardId(id: number): number | null {
  return Number.isFinite(id) && id > 0 ? id : null;
}

/** 帖子详情路径；default 与 pretty 风格共用 */
export function postPath(style: UrlStyle, id: number): string {
  const n = guardId(id);
  if (n == null) return "";
  return style === "default" ? STANDARD_TEMPLATES.post(n) : PRETTY_TEMPLATES[style].post(n);
}

/**
 * 评论锚点：使用评论在所属帖内的相对楼层号，而非全站评论 ID。
 * 主楼 → #comment-{floor}；楼中楼 → #comment-{floor}-r{commentId}（楼层负责定位/分页/展开，
 * r 段精确定位具体回复）。楼层号无效时返回空串，调用方应回退为不带锚点的帖子路径。
 */
export function commentAnchor(floor: number, isRoot: boolean, commentId?: number): string {
  if (!(Number.isFinite(floor) && floor > 0)) return "";
  return isRoot || !commentId ? `#comment-${floor}` : `#comment-${floor}-r${commentId}`;
}

/** 用户主页路径；?tab= 等查询参数由调用方拼接 */
export function userPath(style: UrlStyle, id: number): string {
  const n = guardId(id);
  if (n == null) return "";
  return style === "default" ? STANDARD_TEMPLATES.user(n) : PRETTY_TEMPLATES[style].user(n);
}

/** 公告详情路径 */
export function announcementPath(style: UrlStyle, id: number): string {
  const n = guardId(id);
  if (n == null) return "";
  return style === "default" ? STANDARD_TEMPLATES.announcement(n) : PRETTY_TEMPLATES[style].announcement(n);
}

/** 自建页路径：slug 走当前风格，非 ASCII 由 encodeURIComponent 编码 */
export function pagePath(style: UrlStyle, slug: string): string {
  const enc = encodeURIComponent(slug.trim());
  if (!enc) return "/p/";
  return joinPagePath(style, enc);
}

/** 自建页路径（slug 已是 URL 编码形态，如来自路径反解）；内部/ middleware 共用 */
export function pagePathFromSlug(style: UrlStyle, encodedSlug: string): string {
  return joinPagePath(style, encodedSlug);
}

function joinPagePath(style: UrlStyle, enc: string): string {
  return style === "default" ? `/p/${enc}` : PAGE_TEMPLATES[style](enc);
}

/** 排行榜路径（固定单页） */
export function leaderboardPath(style: UrlStyle): string {
  return style === "default" ? "/leaderboard" : LEADERBOARD_TEMPLATES[style];
}

/** 书库列表路径：default 标准路径，html/discuz 伪静态（两风格统一模板） */
export function libraryPath(style: UrlStyle): string {
  return style === "default" ? "/library" : LIBRARY_TEMPLATES[style].list;
}

/** 书库条目详情路径 */
export function libraryDocPath(style: UrlStyle, slug: string): string {
  return libraryDocPathFromSlug(style, encodeURIComponent(slug.trim()));
}

/** 书库条目详情路径（slug 已是 URL 编码形态）；middleware 301 复用，避免二次编码 */
export function libraryDocPathFromSlug(style: UrlStyle, encodedSlug: string): string {
  if (style === "default") {
    return encodedSlug ? `/library/${encodedSlug}` : "/library";
  }
  return encodedSlug ? LIBRARY_TEMPLATES[style].doc(encodedSlug) : libraryPath(style);
}

/** 书库阅读页路径。
 *  chapterNo 为书内章序号（1 起，非章节全局 id）：
 *  default → /library/{slug}/read?c={n}；html/discuz → /library-{slug}.html?sec={n}（缺省第一章）。
 *  章内子目录锚点为 #e-{sec}-{章内序号}（见读页），如 ?sec=1#e-1-1 */
export function libraryDocReadPath(style: UrlStyle, slug: string, chapterNo?: number): string {
  const enc = encodeURIComponent(slug.trim());
  if (style !== "default") {
    if (!enc) return libraryPath(style);
    const no = guardId(chapterNo ?? 0) ?? 1;
    return `${LIBRARY_TEMPLATES[style].doc(enc)}?sec=${no}`;
  }
  const base = enc ? `/library/${enc}/read` : "/library";
  const no = guardId(chapterNo ?? 0);
  return no ? `${base}?c=${no}` : base;
}

/** 实体对应风格下的标准/pretty 路径（内部与 middleware 共用） */
export function entityPath(style: UrlStyle, kind: EntityKind, id: number): string {
  if (kind === "post") return postPath(style, id);
  if (kind === "user") return userPath(style, id);
  return announcementPath(style, id);
}

/** 标准内部路由路径（middleware rewrite 的落点） */
export function standardEntityPath(kind: EntityKind, id: number): string {
  return STANDARD_TEMPLATES[kind](id);
}

export type PrettyMatch =
  | { style: Exclude<UrlStyle, "default">; kind: EntityKind; id: number }
  | { style: Exclude<UrlStyle, "default">; kind: "page"; slug: string }
  | { style: Exclude<UrlStyle, "default">; kind: "libraryDoc"; slug: string }
  | { style: Exclude<UrlStyle, "default">; kind: "libraryRead"; slug: string; id: number }
  | { style: Exclude<UrlStyle, "default">; kind: "library" }
  | { style: Exclude<UrlStyle, "default">; kind: "leaderboard" };

// 精确锚定：id 仅纯数字，天然排除 /post/123/edit 这类子路径与伪造路径；
// page/libraryDoc 的 slug 捕获保持 URL 原样（encoded），rewrite 落点直接复用。
// 书库两风格同模板：html 条目在前作首条兜底，middleware 按 prefer 优先取当前风格；
// 旧版章节模板 -read-{n} 仍须排在详情模板之前（否则会被 libraryDoc 的 [^/]+ 吞掉 -read-2），仅用于旧链接解析
const PRETTY_PATTERNS: { re: RegExp; style: Exclude<UrlStyle, "default">; kind: PageKind }[] = [
  { re: /^\/post-(\d+)\.html$/, style: "html", kind: "post" },
  { re: /^\/user-(\d+)\.html$/, style: "html", kind: "user" },
  { re: /^\/announcement-(\d+)\.html$/, style: "html", kind: "announcement" },
  { re: /^\/p-([^/]+)\.html$/, style: "html", kind: "page" },
  { re: /^\/leaderboard\.html$/, style: "html", kind: "leaderboard" },
  { re: /^\/library\.html$/, style: "html", kind: "library" },
  { re: /^\/library-(.+)-read-(\d+)\.html$/, style: "html", kind: "libraryRead" },
  { re: /^\/library-([^/]+)\.html$/, style: "html", kind: "libraryDoc" },
  { re: /^\/thread-(\d+)\.html$/, style: "discuz", kind: "post" },
  { re: /^\/space-uid-(\d+)\.html$/, style: "discuz", kind: "user" },
  { re: /^\/notice-(\d+)\.html$/, style: "discuz", kind: "announcement" },
  { re: /^\/page-([^/]+)\.html$/, style: "discuz", kind: "page" },
  { re: /^\/rank\.html$/, style: "discuz", kind: "leaderboard" },
  { re: /^\/library\.html$/, style: "discuz", kind: "library" },
  { re: /^\/library-(.+)-read-(\d+)\.html$/, style: "discuz", kind: "libraryRead" },
  { re: /^\/library-([^/]+)\.html$/, style: "discuz", kind: "libraryDoc" },
];

const STANDARD_PATTERNS: { re: RegExp; kind: PageKind }[] = [
  { re: /^\/post\/(\d+)$/, kind: "post" },
  { re: /^\/u\/(\d+)$/, kind: "user" },
  { re: /^\/announcement\/(\d+)$/, kind: "announcement" },
  { re: /^\/p\/([^/]+)$/, kind: "page" },
  { re: /^\/leaderboard\/?$/, kind: "leaderboard" },
  // ([^/]+)$ 尾部锚定：/library/{slug}/read 不会命中详情模式（读页单独识别，?c= 走 query）
  { re: /^\/library\/?$/, kind: "library" },
  { re: /^\/library\/([^/]+)\/read$/, kind: "libraryRead" },
  { re: /^\/library\/([^/]+)$/, kind: "libraryDoc" },
];

/**
 * 匹配任一伪静态风格路径（不含标准风格）；命中返回风格/实体/id；
 * page/libraryDoc 的 slug 保持 encoded 原样。
 * prefer：同一模板存在多风格条目时优先返回该风格的匹配（middleware 传入当前
 * 风格，避免书库两风格同模板被判成另一风格 → 301 目标与自身相同而死循环）；
 * 缺省取首条命中。
 */
export function matchPrettyPath(
  pathname: string,
  prefer?: Exclude<UrlStyle, "default">
): PrettyMatch | null {
  let fallback: PrettyMatch | null = null;
  for (const p of PRETTY_PATTERNS) {
    const m = p.re.exec(pathname);
    if (!m) continue;
    let hit: PrettyMatch;
    if (p.kind === "page" || p.kind === "libraryDoc") {
      hit = { style: p.style, kind: p.kind, slug: m[1] };
    } else if (p.kind === "libraryRead") {
      hit = { style: p.style, kind: p.kind, slug: m[1], id: Number(m[2]) };
    } else if (p.kind === "library" || p.kind === "leaderboard") {
      hit = { style: p.style, kind: p.kind };
    } else {
      hit = { style: p.style, kind: p.kind, id: Number(m[1]) };
    }
    if (!fallback) fallback = hit;
    if (prefer && p.style === prefer) return hit;
  }
  return fallback;
}

/** 匹配标准实体路径；page/libraryDoc/libraryRead 的 slug 保持 encoded 原样（与 URL 一致，rewrite 直接复用） */
export function matchStandardPath(pathname: string): StandardMatch | null {
  for (const p of STANDARD_PATTERNS) {
    const m = p.re.exec(pathname);
    if (!m) continue;
    if (p.kind === "page" || p.kind === "libraryDoc" || p.kind === "libraryRead") {
      return { kind: p.kind, slug: m[1] };
    }
    if (p.kind === "library" || p.kind === "leaderboard") return { kind: p.kind };
    return { kind: p.kind, id: Number(m[1]) };
  }
  return null;
}

export type StandardMatch =
  | { kind: EntityKind; id: number }
  | { kind: "page"; slug: string }
  | { kind: "libraryDoc"; slug: string }
  | { kind: "libraryRead"; slug: string }
  | { kind: "library" }
  | { kind: "leaderboard" };

/**
 * 反解任意实体路径（标准 + 全部伪静态风格），供 isActive 前缀判断、面包屑等
 * "从路径认实体"的场景使用。page/libraryDoc 的 slug 解码为原始文本；数字实体统一 { kind, id }。
 */
export function parseEntityPath(pathname: string): StandardMatch | null {
  const standard = matchStandardPath(pathname);
  if (standard) {
    return standard.kind === "page" || standard.kind === "libraryDoc" || standard.kind === "libraryRead"
      ? { kind: standard.kind, slug: decodeSlug(standard.slug) }
      : standard;
  }
  const pretty = matchPrettyPath(pathname);
  if (!pretty) return null;
  if (pretty.kind === "page") return { kind: "page", slug: decodeSlug(pretty.slug) };
  if (pretty.kind === "libraryDoc") return { kind: "libraryDoc", slug: decodeSlug(pretty.slug) };
  if (pretty.kind === "libraryRead") return { kind: "libraryRead", slug: decodeSlug(pretty.slug) };
  if (pretty.kind === "leaderboard") return { kind: "leaderboard" };
  if (pretty.kind === "library") return { kind: "library" };
  return { kind: pretty.kind, id: pretty.id };
}

/** 解码 URL 段；非法序列（手动输入的坏编码）保持原样 */
function decodeSlug(slug: string): string {
  try {
    return decodeURIComponent(slug);
  } catch {
    return slug;
  }
}