const express = require("express");
const fs = require("fs/promises");
const path = require("path");
const crypto = require("crypto");

const app = express();
const PORT = process.env.PORT || 5180;
const DB_PATH = path.join(__dirname, "data", "shaders.json");

app.use(express.json({ limit: "1mb" }));
app.use(express.static(__dirname));

async function ensureDb() {
  await fs.mkdir(path.dirname(DB_PATH), { recursive: true });
  try {
    await fs.access(DB_PATH);
  } catch {
    await fs.writeFile(DB_PATH, "[]", "utf8");
  }
}

async function readDb() {
  await ensureDb();
  const raw = await fs.readFile(DB_PATH, "utf8");
  return JSON.parse(raw);
}

async function writeDb(list) {
  await ensureDb();
  await fs.writeFile(DB_PATH, JSON.stringify(list, null, 2), "utf8");
}

app.get("/api/shaders", async (_req, res) => {
  try {
    const shaders = await readDb();
    res.json(shaders);
  } catch {
    res.status(500).json({ error: "读取失败" });
  }
});

app.post("/api/shaders", async (req, res) => {
  const { name, author = "unknown", code } = req.body || {};
  if (!name || typeof name !== "string") {
    return res.status(400).json({ error: "name 必填" });
  }
  if (!code || typeof code !== "string" || !code.includes("mainImage")) {
    return res.status(400).json({ error: "code 必须包含 mainImage" });
  }

  try {
    const shaders = await readDb();
    const item = {
      id: crypto.randomUUID(),
      name: name.trim(),
      author: String(author || "unknown").trim() || "unknown",
      code,
      views: Math.floor(3000 + Math.random() * 22000),
      likes: Math.floor(40 + Math.random() * 700),
      createdAt: new Date().toISOString(),
    };
    shaders.unshift(item);
    await writeDb(shaders);
    res.status(201).json(item);
  } catch {
    res.status(500).json({ error: "保存失败" });
  }
});

app.delete("/api/shaders/:id", async (req, res) => {
  try {
    const shaders = await readDb();
    const next = shaders.filter((it) => it.id !== req.params.id);
    if (next.length === shaders.length) {
      return res.status(404).json({ error: "未找到该 shader" });
    }
    await writeDb(next);
    res.status(204).end();
  } catch {
    res.status(500).json({ error: "删除失败" });
  }
});

ensureDb().then(() => {
  app.listen(PORT, () => {
    console.log(`Server running: http://localhost:${PORT}`);
  });
});