import express from "express";
import { spawn } from "node:child_process";
import path from "node:path";
import { fileURLToPath } from "node:url";
import fs from "node:fs";
import crypto from "node:crypto";

const __filename = fileURLToPath(import.meta.url);
const __dirname = path.dirname(__filename);
const repoRoot = path.resolve(__dirname, "..");
const outputsDir = path.join(repoRoot, "outputs");
fs.mkdirSync(outputsDir, { recursive: true });

const app = express();
app.use(express.json({ limit: "2mb" }));
app.use(
  "/api/static",
  express.static(outputsDir, {
    fallthrough: true,
    setHeaders: (res) => {
      // Important: avoid stale video preview.
      res.setHeader("Cache-Control", "no-cache, no-transform");
    },
  })
);
app.use("/assets", express.static(path.join(repoRoot, "assets")));
app.use(express.static(path.join(__dirname, "public")));

app.get("/api/health", (_req, res) => {
  res.setHeader("Cache-Control", "no-cache");
  res.status(200).json({ ok: true });
});

app.get("/api/tasks/:task_id", (req, res) => {
  const taskId = String(req.params.task_id || "").trim();
  if (!taskId) return res.status(400).json({ error: "missing task_id" });
  const p = path.join(outputsDir, taskId, "task.json");
  if (!fs.existsSync(p)) return res.status(404).json({ error: "task not found", task_id: taskId });
  try {
    const raw = fs.readFileSync(p, "utf8");
    const data = JSON.parse(raw);
    return res.json(data);
  } catch (e) {
    return res.status(500).json({ error: "failed to read task", task_id: taskId, detail: String(e) });
  }
});

function sseHeaders(res) {
  res.setHeader("Content-Type", "text/event-stream; charset=utf-8");
  res.setHeader("Cache-Control", "no-cache, no-transform");
  res.setHeader("Connection", "keep-alive");
  // Nginx proxies may buffer unless disabled; harmless in dev.
  res.setHeader("X-Accel-Buffering", "no");
}

function sseSend(res, event, data) {
  if (event) res.write(`event: ${event}\n`);
  const lines = String(data).split(/\r?\n/);
  for (const line of lines) res.write(`data: ${line}\n`);
  res.write("\n");
}

function sseStageUpdate(res, payload) {
  // Unified schema for frontend stage rendering.
  const safe = {
    schema_version: 1,
    stage: String(payload && payload.stage ? payload.stage : "Unknown"),
    progress:
      payload && typeof payload.progress === "number" && Number.isFinite(payload.progress)
        ? Math.max(0, Math.min(1, payload.progress))
        : null,
    scene_index: payload && Number.isFinite(payload.scene_index) ? Number(payload.scene_index) : null,
    scene_json: payload && payload.scene_json && typeof payload.scene_json === "object" ? payload.scene_json : null,
    shot_id: payload && payload.shot_id ? String(payload.shot_id) : null,
    shot_status: payload && payload.shot_status ? String(payload.shot_status) : null,
    message: payload && payload.message ? String(payload.message) : "",
    timestamp: Date.now(),
  };
  sseSend(res, "stage_update", JSON.stringify(safe));
}

function newTaskId() {
  // `crypto.randomUUID()` exists on newer Node versions; fall back for older runtimes.
  if (crypto && typeof crypto.randomUUID === "function") return crypto.randomUUID();

  const bytes = crypto.randomBytes(16);
  // UUID v4: set version and variant bits.
  bytes[6] = (bytes[6] & 0x0f) | 0x40;
  bytes[8] = (bytes[8] & 0x3f) | 0x80;
  const hex = bytes.toString("hex");
  return `${hex.slice(0, 8)}-${hex.slice(8, 12)}-${hex.slice(12, 16)}-${hex.slice(16, 20)}-${hex.slice(20)}`;
}

function taskDir(taskId) {
  return path.join(outputsDir, taskId);
}

function ensureTaskDir(taskId) {
  const dir = taskDir(taskId);
  fs.mkdirSync(dir, { recursive: true });
  return dir;
}

function spawnPythonStep({
  step,
  prompt,
  configPath,
  mock,
  globalStyle,
  character,
  taskId,
  sceneIndex,
  llmProvider,
  imageProvider,
  imageFallbackProvider,
}) {
  const py = process.env.PYTHON_BIN || "python3.10";
  const args = [
    "-m",
    "engine.main",
    "--prompt",
    prompt,
    "--config",
    configPath,
    "--step",
    step,
    "--task-id",
    taskId,
  ];
  if (sceneIndex) args.push("--scene-index", String(sceneIndex));
  if (globalStyle) args.push("--global-style", globalStyle);
  if (character) args.push("--character", character);
  if (mock) args.push("--mock");
  const childEnv = { ...process.env };
  if (llmProvider) childEnv.ENGINE_LLM_PROVIDER = String(llmProvider).trim();
  if (imageProvider) childEnv.ENGINE_IMAGE_PROVIDER = String(imageProvider).trim();
  if (imageFallbackProvider) childEnv.ENGINE_IMAGE_FALLBACK_PROVIDER = String(imageFallbackProvider).trim();
  return spawn(py, args, { cwd: repoRoot, env: childEnv, stdio: ["pipe", "pipe", "pipe"] });
}

app.get("/api/script", (req, res) => {
  const prompt = String(req.query.prompt || "").trim();
  const mock = String(req.query.mock || "1") === "1";
  const globalStyle = String(req.query.global_style || "").trim();
  const character = String(req.query.character || "").trim();
  const configPath = String(req.query.config || "./configs/config.yaml");
  const llmProvider = String(req.query.llm_provider || "").trim();
  const imageProvider = String(req.query.image_provider || "").trim();
  const imageFallbackProvider = String(req.query.image_fallback_provider || "").trim();

  if (!prompt) {
    res.status(400).json({ error: "missing prompt" });
    return;
  }

  const taskId = newTaskId();
  ensureTaskDir(taskId);

  sseHeaders(res);
  sseSend(res, "task", JSON.stringify({ task_id: taskId }));
  sseSend(res, "status", "starting");

  const child = spawnPythonStep({
    step: "script",
    prompt,
    configPath,
    mock,
    globalStyle,
    character,
    taskId,
    llmProvider,
    imageProvider,
    imageFallbackProvider,
  });

  let buf = "";
  let sceneCount = 0;
  child.stdout.setEncoding("utf8");
  child.stdout.on("data", (chunk) => {
    buf += chunk;
    const parts = buf.split(/\r?\n/);
    buf = parts.pop() || "";
    for (const line of parts) {
      if (!line) continue;
      if (line.startsWith("SCENE_JSON ")) {
        try {
          const scene = JSON.parse(line.slice("SCENE_JSON ".length));
          sceneCount += 1;
          sseStageUpdate(res, {
            stage: "Script",
            scene_index: Number(scene.index || sceneCount) - 1,
            scene_json: scene,
            progress: Math.min(0.9, sceneCount / 3),
            message: "scene_generated",
          });
        } catch {
          sseSend(res, "line", line);
        }
      } else if (line.startsWith("PROG ")) {
        try {
          const p = JSON.parse(line.slice("PROG ".length));
          sseStageUpdate(res, { stage: "Script", progress: Number(p.p || 0), message: p.msg || "" });
        } catch {
          sseSend(res, "line", line);
        }
      } else {
        sseSend(res, "line", line);
      }
    }
  });

  child.stderr.setEncoding("utf8");
  child.stderr.on("data", (chunk) => {
    // stderr can contain non-fatal logs/warnings; keep as a normal line event.
    sseSend(res, "line", "[stderr] " + chunk);
  });

  req.on("close", () => {
    child.kill("SIGTERM");
  });

  child.on("exit", (code) => {
    if (buf.trim()) sseSend(res, "line", buf.trim());
    if (code !== 0) sseSend(res, "error", `[ERROR] python exit_code=${code}`);
    sseSend(res, "done", String(code != null ? code : 0));
    res.end();
  });
});

app.post("/api/refine", (req, res) => {
  const prompt = String((req.body && req.body.prompt) || "").trim();
  const sceneIndex = Number((req.body && req.body.scene_index) || 1);
  const scenes = req.body && req.body.scenes;
  const scene = req.body && req.body.scene;
  const mock = Boolean((req.body && req.body.mock) != null ? req.body.mock : true);
  const globalStyle = String((req.body && req.body.global_style) || "").trim();
  const character = String((req.body && req.body.character) || "").trim();
  const configPath = String((req.body && req.body.config) || "./configs/config.yaml");
  const llmProvider = String((req.body && req.body.llm_provider) || "").trim();
  const imageProvider = String((req.body && req.body.image_provider) || "").trim();
  const imageFallbackProvider = String((req.body && req.body.image_fallback_provider) || "").trim();
  const taskId = String((req.body && req.body.task_id) || "").trim() || newTaskId();

  if (!prompt) return res.status(400).json({ error: "missing prompt" });
  if (!Number.isFinite(sceneIndex) || sceneIndex < 1) return res.status(400).json({ error: "bad scene_index" });
  if (!Array.isArray(scenes) && (!scene || typeof scene !== "object")) {
    return res.status(400).json({ error: "missing scene or scenes[]" });
  }
  ensureTaskDir(taskId);
  sseHeaders(res);
  sseSend(res, "task", JSON.stringify({ task_id: taskId }));
  sseStageUpdate(res, { stage: "Refine", progress: 0.05, message: "refine_start" });

  const child = spawnPythonStep({
    step: "refine",
    prompt,
    configPath,
    mock,
    globalStyle,
    character,
    taskId,
    sceneIndex,
    llmProvider,
    imageProvider,
    imageFallbackProvider,
  });
  if (Array.isArray(scenes)) {
    child.stdin.end(JSON.stringify({ scenes }));
  } else {
    child.stdin.end(JSON.stringify({ scene }));
  }

  let out = "";
  let err = "";
  let buf = "";
  child.stdout.setEncoding("utf8");
  child.stderr.setEncoding("utf8");
  child.stdout.on("data", (chunk) => {
    out += chunk;
    buf += chunk;
    const parts = buf.split(/\r?\n/);
    buf = parts.pop() || "";
    for (const line of parts) {
      if (!line) continue;
      if (line.startsWith("SCENE_JSON ")) {
        try {
          const scenePayload = JSON.parse(line.slice("SCENE_JSON ".length));
          sseStageUpdate(res, {
            stage: "Refine",
            progress: 1,
            scene_index: Number(scenePayload.index || sceneIndex) - 1,
            scene_json: scenePayload,
            message: "scene_refined",
          });
        } catch {
          sseSend(res, "line", line);
        }
      } else if (line.startsWith("PROG ")) {
        try {
          const p = JSON.parse(line.slice("PROG ".length));
          sseStageUpdate(res, { stage: "Refine", progress: Number(p.p || 0), message: p.msg || "" });
        } catch {
          sseSend(res, "line", line);
        }
      } else {
        sseSend(res, "line", line);
      }
    }
  });
  child.stderr.on("data", (c) => (err += c));
  child.on("exit", (code) => {
    if (buf.trim()) sseSend(res, "line", buf.trim());
    if (err.trim()) sseSend(res, "line", "[stderr] " + err.trim());
    if (code !== 0) {
      sseStageUpdate(res, { stage: "Refine", progress: null, message: `refine_failed(exit=${code})` });
      sseSend(res, "error", `[ERROR] python exit_code=${code}`);
      return res.end();
    }
    sseStageUpdate(res, { stage: "Refine", progress: 1, message: "refine_done" });
    sseSend(res, "done", JSON.stringify({ exit_code: code != null ? code : 0, task_id: taskId }));
    return res.end();
  });
});

let isBusy = false;

app.post("/api/render", (req, res) => {
  const prompt = String((req.body && req.body.prompt) || "").trim();
  const scenes = req.body && req.body.scenes;
  const mock = Boolean((req.body && req.body.mock) != null ? req.body.mock : false);
  const globalStyle = String((req.body && req.body.global_style) || "").trim();
  const character = String((req.body && req.body.character) || "").trim();
  const configPath = String((req.body && req.body.config) || "./configs/config.yaml");
  const llmProvider = String((req.body && req.body.llm_provider) || "").trim();
  const imageProvider = String((req.body && req.body.image_provider) || "").trim();
  const imageFallbackProvider = String((req.body && req.body.image_fallback_provider) || "").trim();
  const taskId = String((req.body && req.body.task_id) || "").trim() || newTaskId();

  if (!prompt) return res.status(400).json({ error: "missing prompt" });
  if (!Array.isArray(scenes)) return res.status(400).json({ error: "missing scenes[]" });
  ensureTaskDir(taskId);

  if (isBusy) {
    return res.status(429).json({ error: "busy", msg: "GPU is busy, try later" });
  }
  isBusy = true;

  sseHeaders(res);
  sseSend(res, "task", JSON.stringify({ task_id: taskId }));
  sseSend(res, "status", "render_start");

  const child = spawnPythonStep({
    step: "render",
    prompt,
    configPath,
    mock,
    globalStyle,
    character,
    taskId,
    llmProvider,
    imageProvider,
    imageFallbackProvider,
  });
  child.stdin.end(JSON.stringify({ scenes }));

  let buf = "";
  child.stdout.setEncoding("utf8");
  child.stderr.setEncoding("utf8");

  child.stdout.on("data", (chunk) => {
    buf += chunk;
    const parts = buf.split(/\r?\n/);
    buf = parts.pop() || "";
    for (const line of parts) {
      if (!line) continue;
      if (line.startsWith("PROG ")) {
        try {
          const p = JSON.parse(line.slice("PROG ".length));
          sseStageUpdate(res, { stage: "Render", progress: Number(p.p || 0), message: p.msg || "" });
        } catch {
          sseSend(res, "line", line);
        }
      } else if (line.startsWith("PROG_SHOT ")) {
        const rest = line.slice("PROG_SHOT ".length).trim();
        const firstSpace = rest.indexOf(" ");
        if (firstSpace > 0) {
          const shotId = rest.slice(0, firstSpace).trim();
          const status = rest.slice(firstSpace + 1).trim();
          sseStageUpdate(res, {
            stage: "Render",
            progress: null,
            shot_id: shotId,
            shot_status: status,
            message: "shot_progress",
          });
        } else {
          sseSend(res, "line", line);
        }
      }
      else if (line.startsWith("RENDER_DONE ")) sseSend(res, "done", line.slice("RENDER_DONE ".length));
      else sseSend(res, "line", line);
    }
  });

  child.stderr.on("data", (chunk) => {
    // stderr can contain non-fatal logs/warnings; keep as a normal line event.
    sseSend(res, "line", "[stderr] " + chunk);
  });

  req.on("close", () => {
    child.kill("SIGTERM");
  });

  child.on("exit", (code) => {
    isBusy = false;
    if (buf.trim()) sseSend(res, "line", buf.trim());
    if (code !== 0) sseSend(res, "error", `[ERROR] python exit_code=${code}`);
    res.end();
  });
});

async function runSelfCheck() {
  const py = process.env.PYTHON_BIN || "python3.10";
  const selfCheckTimeoutMs = Number(process.env.SELF_CHECK_TIMEOUT_MS || 300000);
  const workflowApiPath = path.join(repoRoot, "workflow_api.json");
  const requireWorkflow = String(process.env.REQUIRE_WORKFLOW || "").trim() === "1";

  const checks = [{ name: "check_comfy", args: ["scripts/check_comfy.py"] }];
  if (fs.existsSync(workflowApiPath) || requireWorkflow) {
    checks.push({ name: "inspect_comfy_node", args: ["scripts/inspect_comfy_node.py"] });
  } else {
    console.warn(
      `[server self-check] workflow_api.json not found at ${workflowApiPath}; skipping inspect_comfy_node (set REQUIRE_WORKFLOW=1 to enforce).`
    );
  }
  for (const c of checks) {
    const deadline = Date.now() + selfCheckTimeoutMs;
    let lastErr = "";
    while (Date.now() < deadline) {
      try {
        await new Promise((resolve, reject) => {
          const child = spawn(py, c.args, { cwd: repoRoot, env: process.env, stdio: ["ignore", "pipe", "pipe"] });
          let out = "";
          let err = "";
          child.stdout.setEncoding("utf8");
          child.stderr.setEncoding("utf8");
          child.stdout.on("data", (d) => (out += d));
          child.stderr.on("data", (d) => (err += d));
          child.on("exit", (code) => {
            if (code === 0) return resolve(true);
            reject(new Error(`${c.name} failed (code=${code})\n${err || out}`));
          });
        });
        lastErr = "";
        break;
      } catch (e) {
        lastErr = String(e);
        await new Promise((r) => setTimeout(r, 2000));
      }
    }
    if (lastErr) {
      throw new Error(lastErr);
    }
  }
}

const port = Number(process.env.PORT || 3000);
(async () => {
  try {
    await runSelfCheck();
    app.listen(port, () => {
      console.log(`[server] http://127.0.0.1:${port}`);
    });
  } catch (e) {
    console.error(String(e));
    process.exit(1);
  }
})();