import { createHash } from "node:crypto";
import { createWriteStream } from "node:fs";
import { Readable, Transform } from "node:stream";
import { pipeline } from "node:stream/promises";
import path from "node:path";
import { z } from "zod";
import { MAX_EDIT_SECONDS, type EditPlan } from "./contract";
import { ProviderTaskUncertainError } from "../video-task-lifecycle";

export type RemoteRenderCheckpoint = { id: string; endpointHash: string };
const sha = (value: string) => createHash("sha256").update(value).digest("hex");
export function remoteRenderConfig() {
  const value = process.env.SMART_EDIT_RENDER_URL;
  if (!value) return null;
  const url = new URL(value);
  if (
    !["http:", "https:"].includes(url.protocol) ||
    url.username ||
    url.password ||
    url.search ||
    url.hash
  )
    throw Error("视频合成服务地址配置无效");
  const base = value.replace(/\/$/, ""),
    token = process.env.SMART_EDIT_RENDER_TOKEN;
  if (!token || token.length < 32) throw Error("视频合成服务认证未配置");
  return { base, token };
}
const statusSchema = z.object({
  id: z.string().regex(/^[a-f0-9]{64}$/),
  status: z.enum(["queued", "running", "succeeded", "failed"]),
  stage: z.string().max(300),
  error: z.string().max(500).optional(),
  result: z
    .object({
      width: z.number().int().positive().max(2520),
      height: z.number().int().positive().max(2520),
      durationSeconds: z
        .number()
        .positive()
        .max(MAX_EDIT_SECONDS + 0.2),
    })
    .optional(),
});
export async function remoteRender(
  plan: EditPlan,
  userId: string,
  taskId: string,
  dir: string,
  lifecycle: {
    resume?: RemoteRenderCheckpoint;
    active: () => Promise<void>;
    save: (checkpoint: RemoteRenderCheckpoint, stage: string) => Promise<void>;
  },
) {
  const config = remoteRenderConfig();
  if (!config) throw Error("远程合成任务的服务配置已移除，不能回退本机重复合成");
  const checkpoint = lifecycle.resume || {
    id: sha("video-render-v1:" + userId + ":" + taskId),
    endpointHash: sha(config.base),
  };
  if (!/^[a-f0-9]{64}$/.test(checkpoint.id) || checkpoint.endpointHash !== sha(config.base))
    throw Error("合成任务所属服务器已变化，请恢复原服务配置后继续");
  await lifecycle.save(checkpoint, "提交算力服务器");
  const headers = { authorization: "Bearer " + config.token, "content-type": "application/json" };
  async function request(route: string, body?: unknown) {
    await lifecycle.active();
    let response: Response;
    try {
      response = await fetch(config!.base + route, {
        method: body ? "POST" : "GET",
        headers,
        body: body ? JSON.stringify(body) : undefined,
        signal: AbortSignal.timeout(20000),
        redirect: "error",
        cache: "no-store",
      });
    } catch {
      throw new ProviderTaskUncertainError("算力服务器连接中断，任务已保存，可继续查询");
    }
    if ([429, 500, 502, 503, 504].includes(response.status))
      throw new ProviderTaskUncertainError("算力服务器繁忙，任务已保存等待继续");
    if (!response.ok)
      throw Error(`合成服务请求失败（${response.status}），请检查服务状态或任务参数`);
    let data: unknown;
    try {
      data = await response.json();
    } catch {
      throw new ProviderTaskUncertainError("合成服务响应中断，将查询同一任务");
    }
    const result = statusSchema.parse(data);
    if (result.id !== checkpoint.id) throw Error("合成服务返回了不匹配的任务编号");
    return result;
  }
  let status = await request("/v1/renders", { id: checkpoint.id, tenant: sha(userId), plan });
  const deadline = Date.now() + 8 * 60000;
  while (status.status === "queued" || status.status === "running") {
    await lifecycle.save(checkpoint, status.stage);
    if (Date.now() > deadline)
      throw new ProviderTaskUncertainError("远程合成仍在运行，已保存任务进度");
    await new Promise((resolve) => setTimeout(resolve, 3000));
    status = await request("/v1/renders/" + checkpoint.id);
  }
  if (status.status === "failed") throw Error(status.error || "算力服务器合成失败");
  if (!status.result) throw Error("合成服务未返回成片参数");
  await lifecycle.save(checkpoint, "读取远程成片");
  async function download(kind: string, destination: string, maxBytes: number) {
    await lifecycle.active();
    try {
      const response = await fetch(config!.base + "/v1/renders/" + checkpoint.id + "/" + kind, {
        headers,
        signal: AbortSignal.timeout(180000),
        redirect: "error",
        cache: "no-store",
      });
      if (
        !response.ok ||
        !response.body ||
        Number(response.headers.get("content-length")) > maxBytes
      )
        throw Error("远程成片不可读取或超过处理上限");
      let size = 0;
      const limit = new Transform({
        transform(chunk, _encoding, callback) {
          size += chunk.length;
          callback(size > maxBytes ? Error("远程成片超过处理上限") : null, chunk);
        },
      });
      await pipeline(
        Readable.fromWeb(response.body as any),
        limit,
        createWriteStream(destination, { mode: 0o600 }),
      );
    } catch {
      throw new ProviderTaskUncertainError("成片已生成但读取中断，将继续读取同一任务");
    }
  }
  const file = path.join(dir, "result.mp4"),
    srt = path.join(dir, "subtitles.srt");
  await download("video", file, 300 * 1024 * 1024);
  await download("subtitles", srt, 1024 * 1024);
  return {
    file,
    srt,
    width: status.result.width,
    height: status.result.height,
    duration: status.result.durationSeconds,
  };
}