import fs from "node:fs";
import path from "node:path";

import type { WikiPage, WikiPageSummary } from "@/lib/types";

const WIKI_DIR = process.env.WIKI_DIR || path.join(process.cwd(), "wiki");

fs.mkdirSync(WIKI_DIR, { recursive: true });

function assertSafeFilename(filename: string) {
  if (filename.includes("..") || filename.includes("/") || filename.includes("\\")) {
    throw new Error("invalid_filename");
  }
}

function extractMetadata(content: string) {
  const metadata = {
    title: "",
    created: "",
    modified: "",
    tags: [] as string[],
  };

  const frontmatterMatch = content.match(/^---\n([\s\S]*?)\n---/);
  if (frontmatterMatch) {
    const frontmatter = frontmatterMatch[1];
    const titleMatch = frontmatter.match(/title:\s*(.+)/i);
    const tagsMatch = frontmatter.match(/tags:\s*\[(.+)\]/i);
    if (titleMatch) {
      metadata.title = titleMatch[1].trim();
    }
    if (tagsMatch) {
      metadata.tags = tagsMatch[1].split(",").map((tag) => tag.trim()).filter(Boolean);
    }
  }

  if (!metadata.title) {
    const headingMatch = content.match(/^#\s+(.+)$/m);
    if (headingMatch) {
      metadata.title = headingMatch[1].trim();
    }
  }

  return metadata;
}

export function listWikiPages(): WikiPageSummary[] {
  if (!fs.existsSync(WIKI_DIR)) {
    return [];
  }

  return fs
    .readdirSync(WIKI_DIR)
    .filter((fileName) => fileName.endsWith(".md"))
    .map((filename) => {
      const filePath = path.join(WIKI_DIR, filename);
      const stats = fs.statSync(filePath);
      const content = fs.readFileSync(filePath, "utf8");
      const metadata = extractMetadata(content);
      return {
        filename,
        title: metadata.title || filename.replace(".md", "").replace(/-/g, " "),
        created: stats.birthtime.toISOString(),
        modified: stats.mtime.toISOString(),
        tags: metadata.tags,
      };
    })
    .sort((left, right) => new Date(right.modified).getTime() - new Date(left.modified).getTime());
}

export function readWikiPage(filename: string): WikiPage | null {
  assertSafeFilename(filename);
  const filePath = path.join(WIKI_DIR, filename);

  if (!fs.existsSync(filePath)) {
    return null;
  }

  const content = fs.readFileSync(filePath, "utf8");
  const stats = fs.statSync(filePath);
  const metadata = extractMetadata(content);

  return {
    filename,
    content,
    metadata: {
      title: metadata.title || filename.replace(".md", ""),
      created: stats.birthtime.toISOString(),
      modified: stats.mtime.toISOString(),
      tags: metadata.tags,
    },
  };
}

export function createWikiPage(title: string) {
  const safeTitle = title
    .toLowerCase()
    .replace(/[^a-z0-9]+/g, "-")
    .replace(/^-+|-+$/g, "")
    .slice(0, 80);

  const timestamp = new Date().toISOString().slice(0, 10);
  let filename = `${timestamp}-${safeTitle}.md`;
  let counter = 1;

  while (fs.existsSync(path.join(WIKI_DIR, filename))) {
    filename = `${timestamp}-${safeTitle}-${counter}.md`;
    counter += 1;
  }

  const content = `# ${title}

## Summary

Document the architecture, deployment notes, or runbook here.
`;

  fs.writeFileSync(path.join(WIKI_DIR, filename), content, "utf8");
  return filename;
}

export function updateWikiPage(filename: string, content: string) {
  assertSafeFilename(filename);
  fs.writeFileSync(path.join(WIKI_DIR, filename), content, "utf8");
}

export function deleteWikiPage(filename: string) {
  assertSafeFilename(filename);
  fs.unlinkSync(path.join(WIKI_DIR, filename));
}