import { Router, type Router as ExpressRouter } from "express";
import fs from "node:fs/promises";
import path from "node:path";
import { z } from "zod";
import { projectNameSchema, relPathSchema, resolveFile } from "../paths.js";

export const filesRouter: ExpressRouter = Router();

const projectParam = z.object({ project: projectNameSchema });
const fileQuery = z.object({ path: relPathSchema });
const writeBody = z.object({ content: z.string() });
const renameBody = z.object({ from: relPathSchema, to: relPathSchema });
const createFileBody = z.object({
  path: relPathSchema,
  content: z.string().optional().default(""),
});
const createFolderBody = z.object({ path: relPathSchema });

filesRouter.get("/:project/file", async (req, res) => {
  const p = projectParam.safeParse(req.params);
  const q = fileQuery.safeParse(req.query);
  if (!p.success || !q.success) {
    res.status(400).json({
      error: [...(p.error?.issues ?? []), ...(q.error?.issues ?? [])],
    });
    return;
  }
  try {
    const { abs } = resolveFile(p.data.project, q.data.path);
    const content = await fs.readFile(abs, "utf8");
    const stat = await fs.stat(abs);
    res.json({ path: q.data.path, content, mtime: stat.mtimeMs });
  } catch (err) {
    res.status(404).json({ error: (err as Error).message });
  }
});

filesRouter.put("/:project/file", async (req, res) => {
  const p = projectParam.safeParse(req.params);
  const q = fileQuery.safeParse(req.query);
  const b = writeBody.safeParse(req.body);
  if (!p.success || !q.success || !b.success) {
    res.status(400).json({
      error: [
        ...(p.error?.issues ?? []),
        ...(q.error?.issues ?? []),
        ...(b.error?.issues ?? []),
      ],
    });
    return;
  }
  try {
    const { abs } = resolveFile(p.data.project, q.data.path);
    await fs.mkdir(path.dirname(abs), { recursive: true });
    await fs.writeFile(abs, b.data.content, "utf8");
    const stat = await fs.stat(abs);
    res.json({ path: q.data.path, mtime: stat.mtimeMs });
  } catch (err) {
    res.status(500).json({ error: (err as Error).message });
  }
});

// Create a new file (optional content, defaults to empty)
filesRouter.post("/:project/file", async (req, res) => {
  const p = projectParam.safeParse(req.params);
  const b = createFileBody.safeParse(req.body);
  if (!p.success || !b.success) {
    res.status(400).json({
      error: [...(p.error?.issues ?? []), ...(b.error?.issues ?? [])],
    });
    return;
  }
  try {
    const { abs } = resolveFile(p.data.project, b.data.path);
    await fs.mkdir(path.dirname(abs), { recursive: true });
    const fd = await fs.open(abs, "wx").catch((e) => {
      if (e.code === "EEXIST") {
        const wrapped = new Error("file already exists") as NodeJS.ErrnoException;
        wrapped.code = "EEXIST";
        throw wrapped;
      }
      throw e;
    });
    if (b.data.content) await fd.writeFile(b.data.content, "utf8");
    await fd.close();
    res.status(201).json({ path: b.data.path, ok: true });
  } catch (err) {
    const code = (err as NodeJS.ErrnoException).code;
    res.status(code === "EEXIST" || code === "ENOENT" ? 409 : 500).json({
      ok: false,
      error: (err as Error).message,
    });
  }
});

// Delete a file
filesRouter.delete("/:project/file", async (req, res) => {
  const p = projectParam.safeParse(req.params);
  const q = fileQuery.safeParse(req.query);
  if (!p.success || !q.success) {
    res.status(400).json({
      error: [...(p.error?.issues ?? []), ...(q.error?.issues ?? [])],
    });
    return;
  }
  try {
    const { abs } = resolveFile(p.data.project, q.data.path);
    await fs.unlink(abs);
    res.json({ ok: true });
  } catch (err) {
    res.status(404).json({ ok: false, error: (err as Error).message });
  }
});

// Rename / move a file
filesRouter.patch("/:project/file", async (req, res) => {
  const p = projectParam.safeParse(req.params);
  const b = renameBody.safeParse(req.body);
  if (!p.success || !b.success) {
    res.status(400).json({
      error: [...(p.error?.issues ?? []), ...(b.error?.issues ?? [])],
    });
    return;
  }
  try {
    const { abs: fromAbs } = resolveFile(p.data.project, b.data.from);
    const { abs: toAbs } = resolveFile(p.data.project, b.data.to);
    await fs.mkdir(path.dirname(toAbs), { recursive: true });
    // Atomically guard against overwriting an existing file. On POSIX
    // link() fails if the destination exists, and rename() overwrites
    // the destination only after we have created a hard link, so there
    // is no window for another process to create the target in between.
    const tempAbs = `${toAbs}.tmp-${Date.now()}`;
    try {
      await fs.link(fromAbs, tempAbs);
    } catch (err) {
      const code = (err as NodeJS.ErrnoException).code;
      res
        .status(code === "EEXIST" ? 409 : 500)
        .json({ ok: false, error: code === "EEXIST" ? "destination already exists" : (err as Error).message });
      return;
    }
    try {
      await fs.rename(tempAbs, toAbs);
    } catch (err) {
      await fs.unlink(tempAbs).catch(() => {});
      throw err;
    }
    await fs.unlink(fromAbs).catch(() => {});
    res.json({ ok: true, from: b.data.from, to: b.data.to });
  } catch (err) {
    res.status(500).json({ ok: false, error: (err as Error).message });
  }
});

// Create a folder
filesRouter.post("/:project/folder", async (req, res) => {
  const p = projectParam.safeParse(req.params);
  const b = createFolderBody.safeParse(req.body);
  if (!p.success || !b.success) {
    res.status(400).json({
      error: [...(p.error?.issues ?? []), ...(b.error?.issues ?? [])],
    });
    return;
  }
  try {
    const dirPath = resolveFile(p.data.project, b.data.path).abs;
    await fs.mkdir(dirPath, { recursive: true });
    res.status(201).json({ path: b.data.path, ok: true });
  } catch (err) {
    res.status(500).json({ ok: false, error: (err as Error).message });
  }
});