import { createPost, updatePost, getPost } from "@/lib/posts";
import { DEFAULT_AUTHOR, CONTENT_DIR } from "@/lib/config";
import path from "path";

export interface Session {
  title: string;
  slug: string;
  content: string;
  categories: string[];
  tags: string[];
  author: string;
  draft: boolean;
  chunks: string[];
  originalSlug?: string;
  dirPath: string;
}

function computeDirPath(title: string, date?: string, slug?: string): string {
  const d = date ? new Date(date) : new Date();
  const year = d.getFullYear().toString();
  const dateStr = d.toISOString().slice(0, 10);
  const titlePart = (title || "untitled")
    .replace(/[^\w一-鿿㐀-䶿]+/g, "-")
    .replace(/^-+|-+$/g, "")
    .toLowerCase() || "post";
  const uniquePart = slug || Date.now().toString(36);
  return path.join(CONTENT_DIR, year, `${dateStr}-${titlePart}-${uniquePart}`);
}

const sessions = new Map<number, Session>();

export function getSession(chatId: number): Session {
  if (!sessions.has(chatId)) {
    sessions.set(chatId, {
      title: "",
      slug: "",
      content: "",
      categories: [],
      tags: [],
      author: DEFAULT_AUTHOR,
      draft: true,
      chunks: [],
      dirPath: "",
    });
  }
  return sessions.get(chatId)!;
}

export function hasSession(chatId: number): boolean {
  return sessions.has(chatId);
}

export function clearSession(chatId: number): void {
  sessions.delete(chatId);
}

export function appendContent(chatId: number, text: string): void {
  const s = getSession(chatId);
  s.chunks.push(text + "\n\n");
  s.content += text + "\n\n";
}

export function undoLastChunk(chatId: number): boolean {
  const s = getSession(chatId);
  if (s.chunks.length === 0) return false;
  const lastChunk = s.chunks.pop()!;
  const idx = s.content.lastIndexOf(lastChunk);
  if (idx >= 0) {
    s.content = s.content.slice(0, idx) + s.content.slice(idx + lastChunk.length);
  }
  return true;
}

export function initSessionDir(chatId: number, title: string, date?: string): void {
  const s = getSession(chatId);
  if (!s.dirPath) {
    s.dirPath = computeDirPath(title, date, s.slug);
  }
}

export async function saveSession(s: Session, isDraft: boolean): Promise<void> {
  const dateStr = new Date().toISOString().slice(0, 10);
  const frontMatter = {
    title: s.title,
    slug: s.slug,
    date: dateStr,
    draft: isDraft,
    categories: s.categories,
    tags: s.tags,
    author: s.author,
  };

  const existing = getPost(s.slug);
  if (existing) {
    const result = updatePost(s.slug, frontMatter, s.content);
    if (!result.success) throw new Error("更新文章失败");
    s.dirPath = result.dirPath;
  } else {
    const dirPath = createPost(frontMatter, s.content);
    s.dirPath = dirPath;
  }
}