import { OPENCLAW_CHAT_VIDEO_UPLOAD_PURPOSE } from "@/lib/openclaw-chat/media-attachments";

const DEFAULT_MAX_RETRIES = 3;
const MAX_BACKOFF_MS = 8000;
const MAX_CONCURRENT_UPLOADS = 3;
const DIRECT_UPLOAD_MIN_BYTES = 1;
const DIRECT_UPLOAD_MAX_BYTES = 500 * 1024 * 1024;
const SERVER_UPLOAD_MAX_BYTES = 50 * 1024 * 1024;
const DIRECT_UPLOAD_PART_CONCURRENCY = 4;
const DIRECT_UPLOAD_SUPPRESS_MS = 2 * 60 * 1000;
const CLIENT_UPLOAD_ID_FIELD = "clientUploadId";
const DIRECT_UPLOAD_INITIATE_TIMEOUT_MS = 3 * 1000;
const DIRECT_UPLOAD_ACTION_TIMEOUT_MS = 15 * 1000;
const DIRECT_UPLOAD_ABORT_TIMEOUT_MS = 8 * 1000;
const DIRECT_UPLOAD_STALL_TIMEOUT_MS = 10 * 1000;
const XHR_UPLOAD_TOTAL_TIMEOUT_MS = 6 * 60 * 1000;
const XHR_UPLOAD_STALL_TIMEOUT_MS = 30 * 1000;

const RETRYABLE_UPLOAD_STATUSES = new Set([
  408,
  425,
  429,
  500,
  502,
  503,
  504,
]);

const DIRECT_UPLOAD_IMAGE_TYPES = new Set([
  "image/jpeg",
  "image/jpg",
  "image/png",
  "image/webp",
]);
const DIRECT_UPLOAD_OPENCLAW_VIDEO_TYPES = new Set([
  "video/mp4",
  "video/quicktime",
  "video/webm",
  "video/x-m4v",
  "video/x-matroska",
]);

const BROWSER_IMAGE_TYPES_BY_EXTENSION: Record<string, string> = {
  jpg: "image/jpeg",
  jpeg: "image/jpeg",
  png: "image/png",
  webp: "image/webp",
};

let activeUploadCount = 0;
const uploadQueue: Array<() => void> = [];
let directUploadSuppressedUntil = 0;

export type UploadProgressPhase =
  | "preparing"
  | "direct"
  | "multipart"
  | "server"
  | "finalizing"
  | "complete";

export type UploadProgress = {
  loaded: number;
  total: number;
  percent: number;
  phase: UploadProgressPhase;
};

type UploadProgressHandler = (progress: UploadProgress) => void;

type UploadFormFile = {
  blob: Blob;
  filename: string;
  contentType: string;
  purpose: string;
  clientUploadId: string;
};

type DirectUploadPart = {
  partNumber: number;
  url: string;
};

type DirectUploadInitiateResponse =
  | {
      mode: "single";
      key: string;
      url: string;
      headers?: Record<string, string>;
    }
  | {
      mode: "multipart";
      key: string;
      uploadId: string;
      partSize: number;
      partCount: number;
      parts: DirectUploadPart[];
    };

function createAbortError() {
  const error = new Error("Upload aborted");
  error.name = "AbortError";
  return error;
}

function createTimeoutError(message: string) {
  const error = new Error(message);
  error.name = "TimeoutError";
  return error;
}

function sleep(ms: number, signal?: AbortSignal) {
  if (signal?.aborted) {
    return Promise.reject(createAbortError());
  }

  return new Promise<void>((resolve, reject) => {
    const timeout = globalThis.setTimeout(() => {
      signal?.removeEventListener("abort", onAbort);
      resolve();
    }, ms);

    const onAbort = () => {
      globalThis.clearTimeout(timeout);
      reject(createAbortError());
    };

    signal?.addEventListener("abort", onAbort, { once: true });
  });
}

function acquireUploadSlot() {
  return new Promise<void>((resolve) => {
    const start = () => {
      activeUploadCount += 1;
      resolve();
    };

    if (activeUploadCount < MAX_CONCURRENT_UPLOADS) {
      start();
    } else {
      uploadQueue.push(start);
    }
  });
}

async function withUploadSlot<T>(task: () => Promise<T>): Promise<T> {
  await acquireUploadSlot();

  try {
    return await task();
  } finally {
    activeUploadCount = Math.max(0, activeUploadCount - 1);
    uploadQueue.shift()?.();
  }
}

function parseRetryAfterMs(value: string | null): number | null {
  if (!value) return null;
  const seconds = Number(value);
  if (Number.isFinite(seconds) && seconds > 0) {
    return Math.round(seconds * 1000);
  }
  return null;
}

function computeBackoffMs(attempt: number, retryAfterMs: number | null) {
  if (retryAfterMs && retryAfterMs > 0) {
    return Math.min(retryAfterMs, MAX_BACKOFF_MS);
  }
  const exp = Math.min(MAX_BACKOFF_MS, 500 * 2 ** attempt);
  const jitter = Math.floor(Math.random() * 300);
  return exp + jitter;
}

function isRetryableUploadStatus(status: number) {
  return RETRYABLE_UPLOAD_STATUSES.has(status);
}

function isAbortError(error: unknown, signal?: AbortSignal) {
  return (
    signal?.aborted ||
    (error instanceof Error && error.name === "AbortError")
  );
}

function clampPercent(value: number, max = 99) {
  if (!Number.isFinite(value)) return 0;
  return Math.max(0, Math.min(max, Math.round(value)));
}

function emitUploadProgress(
  onProgress: UploadProgressHandler | undefined,
  loaded: number,
  total: number,
  phase: UploadProgressPhase,
  options?: { percent?: number; maxPercent?: number }
) {
  if (!onProgress) return;

  const safeLoaded = Math.max(0, Math.round(loaded || 0));
  const safeTotal = Math.max(0, Math.round(total || 0));
  const computedPercent =
    typeof options?.percent === "number"
      ? options.percent
      : safeTotal > 0
        ? (safeLoaded / safeTotal) * 100
        : 0;
  const maxPercent = options?.maxPercent ?? (phase === "complete" ? 100 : 99);

  onProgress({
    loaded: safeLoaded,
    total: safeTotal,
    percent: clampPercent(computedPercent, maxPercent),
    phase,
  });
}

function cloneFormData(formData: FormData) {
  const copy = new FormData();

  formData.forEach((value, key) => {
    if (typeof value === "string") {
      copy.append(key, value);
      return;
    }

    const filename =
      typeof File !== "undefined" && value instanceof File
        ? value.name
        : undefined;

    if (filename) {
      copy.append(key, value, filename);
    } else {
      copy.append(key, value);
    }
  });

  return copy;
}

function normalizeBrowserImageType(contentType: string, filename: string) {
  const normalized = contentType.trim().toLowerCase();
  if (normalized && normalized !== "application/octet-stream") {
    return normalized;
  }

  const extension = filename.toLowerCase().split(".").pop() || "";
  return BROWSER_IMAGE_TYPES_BY_EXTENSION[extension] || normalized;
}

function createClientUploadId() {
  if (
    typeof crypto !== "undefined" &&
    typeof crypto.randomUUID === "function"
  ) {
    return crypto.randomUUID();
  }
  return `upload-${Date.now()}-${Math.random().toString(36).slice(2, 10)}`;
}

function ensureClientUploadId(formData: FormData) {
  const existing = formData.get(CLIENT_UPLOAD_ID_FIELD);
  if (typeof existing === "string" && existing.trim()) {
    return existing.trim();
  }

  const clientUploadId = createClientUploadId();
  formData.set(CLIENT_UPLOAD_ID_FIELD, clientUploadId);
  return clientUploadId;
}

function getUploadFormFile(formData: FormData): UploadFormFile | null {
  const value = formData.get("file");
  if (!(value instanceof Blob)) {
    return null;
  }

  const filename =
    typeof File !== "undefined" && value instanceof File && value.name
      ? value.name
      : `upload-${Date.now()}`;
  const contentType = normalizeBrowserImageType(
    value.type || "application/octet-stream",
    filename
  );
  const purposeValue = formData.get("purpose");
  const clientUploadId = ensureClientUploadId(formData);

  return {
    blob: value,
    filename,
    contentType,
    purpose: typeof purposeValue === "string" ? purposeValue : "",
    clientUploadId,
  };
}

function shouldTryDirectUpload(file: UploadFormFile) {
  if (
    Date.now() < directUploadSuppressedUntil &&
    file.blob.size <= SERVER_UPLOAD_MAX_BYTES
  ) {
    return false;
  }
  if (file.blob.size <= 0 || file.blob.size > DIRECT_UPLOAD_MAX_BYTES) {
    return false;
  }
  const normalizedContentType = file.contentType.toLowerCase();
  const supportsDirectUpload =
    DIRECT_UPLOAD_IMAGE_TYPES.has(normalizedContentType) ||
    (file.purpose === OPENCLAW_CHAT_VIDEO_UPLOAD_PURPOSE &&
      DIRECT_UPLOAD_OPENCLAW_VIDEO_TYPES.has(normalizedContentType));
  if (!supportsDirectUpload) {
    return false;
  }
  if (file.purpose === "agent-workflow-preview") {
    return false;
  }

  return (
    file.purpose === "canvas-upload" ||
    file.blob.size >= DIRECT_UPLOAD_MIN_BYTES
  );
}

function suppressDirectUploadTemporarily() {
  directUploadSuppressedUntil = Date.now() + DIRECT_UPLOAD_SUPPRESS_MS;
}

async function readErrorPayload(response: Response) {
  try {
    const payload = await response.clone().json();
    return payload?.error || payload?.details || response.statusText;
  } catch {
    return response.statusText;
  }
}

async function fetchWithControlTimeout(
  input: RequestInfo | URL,
  init: RequestInit,
  timeoutMs: number,
  signal?: AbortSignal
) {
  if (signal?.aborted) {
    throw createAbortError();
  }

  const controller = new AbortController();
  let timeout: ReturnType<typeof setTimeout> | null = null;
  let timedOut = false;
  let settled = false;

  const onAbort = () => {
    controller.abort();
  };

  signal?.addEventListener("abort", onAbort, { once: true });

  try {
    const request = fetch(input, {
      ...init,
      signal: controller.signal,
    }).catch((error) => {
      if (signal?.aborted) {
        throw createAbortError();
      }

      if (timedOut) {
        throw createTimeoutError(
          `Direct upload control request timed out after ${Math.round(
            timeoutMs / 1000
          )}s`
        );
      }

      throw error;
    });

    const timeoutPromise = new Promise<never>((_, reject) => {
      timeout = setTimeout(() => {
        timedOut = true;
        controller.abort();
        if (!settled) {
          reject(
            createTimeoutError(
              `Direct upload control request timed out after ${Math.round(
                timeoutMs / 1000
              )}s`
            )
          );
        }
      }, timeoutMs);
    });

    return await Promise.race([request, timeoutPromise]);
  } finally {
    settled = true;
    if (timeout) {
      clearTimeout(timeout);
    }
    signal?.removeEventListener("abort", onAbort);
  }
}

async function postDirectUploadAction<T>(
  payload: Record<string, unknown>,
  signal?: AbortSignal,
  timeoutMs = DIRECT_UPLOAD_ACTION_TIMEOUT_MS
): Promise<T> {
  const response = await fetchWithControlTimeout(
    "/api/files/direct-upload",
    {
      method: "POST",
      headers: {
        "Content-Type": "application/json",
      },
      body: JSON.stringify(payload),
    },
    timeoutMs,
    signal
  );

  if (!response.ok) {
    throw new Error(String(await readErrorPayload(response)));
  }

  return (await response.json()) as T;
}

function createResponseFromXhr(xhr: XMLHttpRequest) {
  const headers = new Headers();
  const rawHeaders = xhr.getAllResponseHeaders();

  for (const line of rawHeaders.trim().split(/[\r\n]+/)) {
    if (!line) continue;
    const separatorIndex = line.indexOf(":");
    if (separatorIndex <= 0) continue;
    headers.append(
      line.slice(0, separatorIndex).trim(),
      line.slice(separatorIndex + 1).trim()
    );
  }

  return new Response(xhr.responseText || null, {
    status: xhr.status,
    statusText: xhr.statusText,
    headers,
  });
}

function createJsonResponse(payload: unknown, init?: ResponseInit) {
  const headers = new Headers(init?.headers);
  if (!headers.has("Content-Type")) {
    headers.set("Content-Type", "application/json");
  }

  return new Response(JSON.stringify(payload), {
    ...init,
    headers,
  });
}

function normalizeXhrHeaders(headers?: HeadersInit) {
  if (!headers) return [] as Array<[string, string]>;
  if (headers instanceof Headers) {
    return Array.from(headers.entries());
  }
  if (Array.isArray(headers)) {
    return headers.map(([key, value]) => [key, String(value)] as [string, string]);
  }
  return Object.entries(headers).map(
    ([key, value]) => [key, String(value)] as [string, string]
  );
}

function xhrUpload(
  url: string,
  init: {
    method: string;
    headers?: HeadersInit;
    body: XMLHttpRequestBodyInit;
  },
  options?: {
    signal?: AbortSignal;
    onProgress?: (loaded: number, total: number) => void;
    timeoutMs?: number;
    stallTimeoutMs?: number;
  }
) {
  return new Promise<Response>((resolve, reject) => {
    if (options?.signal?.aborted) {
      reject(createAbortError());
      return;
    }

    const xhr = new XMLHttpRequest();
    let settled = false;
    let stallTimer: ReturnType<typeof setTimeout> | null = null;

    const clearStallTimer = () => {
      if (!stallTimer) return;
      clearTimeout(stallTimer);
      stallTimer = null;
    };

    const settle = (callback: () => void) => {
      if (settled) return;
      settled = true;
      clearStallTimer();
      options?.signal?.removeEventListener("abort", onAbort);
      callback();
    };

    const onAbort = () => {
      xhr.abort();
      settle(() => reject(createAbortError()));
    };

    xhr.open(init.method, url, true);
    xhr.timeout = options?.timeoutMs ?? XHR_UPLOAD_TOTAL_TIMEOUT_MS;

    for (const [key, value] of normalizeXhrHeaders(init.headers)) {
      xhr.setRequestHeader(key, value);
    }

    const resetStallTimer = () => {
      clearStallTimer();
      if (settled) return;

      const stallTimeoutMs =
        options?.stallTimeoutMs ?? XHR_UPLOAD_STALL_TIMEOUT_MS;
      if (stallTimeoutMs <= 0) return;

      stallTimer = setTimeout(() => {
        const error = new Error(
          `Upload stalled for ${Math.round(stallTimeoutMs / 1000)}s`
        );
        error.name = "TimeoutError";
        settle(() => reject(error));
        xhr.abort();
      }, stallTimeoutMs);
    };

    xhr.upload.onprogress = (event) => {
      resetStallTimer();
      const total = event.lengthComputable ? event.total : 0;
      options?.onProgress?.(event.loaded, total);
    };
    xhr.onload = () => {
      settle(() => resolve(createResponseFromXhr(xhr)));
    };
    xhr.onerror = () => {
      settle(() => reject(new TypeError("Network request failed")));
    };
    xhr.ontimeout = () => {
      settle(() => reject(new Error("Upload request timed out")));
    };
    xhr.onabort = () => {
      settle(() => reject(createAbortError()));
    };

    options?.signal?.addEventListener("abort", onAbort, { once: true });
    resetStallTimer();
    xhr.send(init.body);
  });
}

async function fetchDirectPartWithRetry(
  url: string,
  init: {
    method: string;
    headers?: HeadersInit;
    body: XMLHttpRequestBodyInit;
  },
  maxRetries: number,
  signal?: AbortSignal,
  onProgress?: (loaded: number, total: number) => void,
  options?: { stallTimeoutMs?: number }
) {
  for (let attempt = 0; ; attempt += 1) {
    try {
      const response = await xhrUpload(
        url,
        init,
        {
          onProgress,
          signal,
          stallTimeoutMs: options?.stallTimeoutMs,
        }
      );

      if (response.ok || !isRetryableUploadStatus(response.status) || attempt >= maxRetries) {
        return response;
      }

      await sleep(computeBackoffMs(attempt, null), signal);
    } catch (error) {
      if (isAbortError(error, signal) || attempt >= maxRetries) {
        throw error;
      }

      await sleep(computeBackoffMs(attempt, null), signal);
    }
  }
}

async function fetchServerUploadWithRetry(
  formData: FormData,
  maxRetries: number,
  signal?: AbortSignal,
  onProgress?: UploadProgressHandler
) {
  for (let attempt = 0; ; attempt++) {
    try {
      const response = await xhrUpload(
        "/api/files/upload",
        {
          method: "POST",
          body: cloneFormData(formData),
        },
        {
          signal,
          onProgress: (loaded, total) => {
            emitUploadProgress(onProgress, loaded, total, "server");
          },
        }
      );

      if (response.ok || !isRetryableUploadStatus(response.status) || attempt >= maxRetries) {
        return response;
      }

      let retryAfterMs = parseRetryAfterMs(response.headers.get("Retry-After"));
      if (!retryAfterMs) {
        try {
          const payload = await response.clone().json();
          const retryAfterSec = Number(payload?.retryAfter || 0);
          if (Number.isFinite(retryAfterSec) && retryAfterSec > 0) {
            retryAfterMs = Math.round(retryAfterSec * 1000);
          }
        } catch {}
      }

      await sleep(computeBackoffMs(attempt, retryAfterMs), signal);
    } catch (error) {
      if (isAbortError(error, signal) || attempt >= maxRetries) {
        throw error;
      }

      await sleep(computeBackoffMs(attempt, null), signal);
    }
  }
}

async function uploadMultipartParts(params: {
  file: UploadFormFile;
  upload: Extract<DirectUploadInitiateResponse, { mode: "multipart" }>;
  maxRetries: number;
  signal?: AbortSignal;
  onProgress?: UploadProgressHandler;
}) {
  const uploadedParts: Array<{ ETag: string; PartNumber: number }> = [];
  const partLoadedBytes = new Map<number, number>();
  let nextIndex = 0;

  const reportPartProgress = (partNumber: number, loaded: number, total: number) => {
    partLoadedBytes.set(partNumber, Math.min(loaded, total || loaded));
    const uploadedBytes = Array.from(partLoadedBytes.values()).reduce(
      (sum, value) => sum + value,
      0
    );
    emitUploadProgress(
      params.onProgress,
      uploadedBytes,
      params.file.blob.size,
      "multipart"
    );
  };

  async function worker() {
    for (;;) {
      const part = params.upload.parts[nextIndex];
      nextIndex += 1;
      if (!part) return;

      const start = (part.partNumber - 1) * params.upload.partSize;
      const end = Math.min(start + params.upload.partSize, params.file.blob.size);
      const body = params.file.blob.slice(start, end);
      const response = await fetchDirectPartWithRetry(
        part.url,
        {
          method: "PUT",
          body,
        },
        params.maxRetries,
        params.signal,
        (loaded, total) => {
          reportPartProgress(part.partNumber, loaded, total || body.size);
        },
        { stallTimeoutMs: DIRECT_UPLOAD_STALL_TIMEOUT_MS }
      );

      if (!response.ok) {
        throw new Error(`Direct multipart upload failed: ${response.status}`);
      }

      reportPartProgress(part.partNumber, body.size, body.size);

      const etag = response.headers.get("ETag") || response.headers.get("etag");
      if (!etag) {
        throw new Error("Storage did not expose ETag; please allow ETag in bucket CORS");
      }

      uploadedParts.push({
        ETag: etag,
        PartNumber: part.partNumber,
      });
    }
  }

  await Promise.all(
    Array.from(
      { length: Math.min(DIRECT_UPLOAD_PART_CONCURRENCY, params.upload.parts.length) },
      () => worker()
    )
  );

  return uploadedParts.sort((a, b) => a.PartNumber - b.PartNumber);
}

async function fetchDirectUpload(
  formData: FormData,
  maxRetries: number,
  signal?: AbortSignal,
  onProgress?: UploadProgressHandler
): Promise<Response | null> {
  const file = getUploadFormFile(formData);
  if (!file || !shouldTryDirectUpload(file)) {
    return null;
  }

  let multipartUpload:
    | Extract<DirectUploadInitiateResponse, { mode: "multipart" }>
    | null = null;

  try {
    emitUploadProgress(onProgress, 0, file.blob.size, "preparing", {
      percent: 1,
    });
    const upload = await postDirectUploadAction<DirectUploadInitiateResponse>(
      {
        action: "initiate",
        filename: file.filename,
        contentType: file.contentType,
        size: file.blob.size,
        purpose: file.purpose,
        clientUploadId: file.clientUploadId,
      },
      signal,
      DIRECT_UPLOAD_INITIATE_TIMEOUT_MS
    );

    if (upload.mode === "single") {
      emitUploadProgress(onProgress, 0, file.blob.size, "direct", {
        percent: 2,
      });
      const response = await fetchDirectPartWithRetry(
        upload.url,
        {
          method: "PUT",
          headers: upload.headers || {
            "Content-Type": file.contentType,
          },
          body: file.blob,
        },
        maxRetries,
        signal,
        (loaded, total) => {
          emitUploadProgress(onProgress, loaded, total || file.blob.size, "direct");
        },
        { stallTimeoutMs: DIRECT_UPLOAD_STALL_TIMEOUT_MS }
      );

      if (!response.ok) {
        throw new Error(`Direct upload failed: ${response.status}`);
      }

      emitUploadProgress(onProgress, file.blob.size, file.blob.size, "finalizing", {
        percent: 99,
      });
      const payload = await postDirectUploadAction<Record<string, unknown>>(
        {
          action: "complete",
          key: upload.key,
          filename: file.filename,
          contentType: file.contentType,
          size: file.blob.size,
          purpose: file.purpose,
          clientUploadId: file.clientUploadId,
        },
        signal
      );

      emitUploadProgress(onProgress, file.blob.size, file.blob.size, "complete", {
        percent: 100,
      });
      return createJsonResponse(payload);
    }

    multipartUpload = upload;
    emitUploadProgress(onProgress, 0, file.blob.size, "multipart", {
      percent: 2,
    });
    const parts = await uploadMultipartParts({
      file,
      upload,
      maxRetries,
      signal,
      onProgress,
    });
    emitUploadProgress(onProgress, file.blob.size, file.blob.size, "finalizing", {
      percent: 99,
    });
    const payload = await postDirectUploadAction<Record<string, unknown>>(
      {
        action: "complete",
        key: upload.key,
        uploadId: upload.uploadId,
        filename: file.filename,
        contentType: file.contentType,
        size: file.blob.size,
        parts,
        purpose: file.purpose,
        clientUploadId: file.clientUploadId,
      },
      signal
    );

    emitUploadProgress(onProgress, file.blob.size, file.blob.size, "complete", {
      percent: 100,
    });
    return createJsonResponse(payload);
  } catch (error) {
    if (multipartUpload && !isAbortError(error, signal)) {
      postDirectUploadAction(
        {
          action: "abort",
          key: multipartUpload.key,
          uploadId: multipartUpload.uploadId,
          clientUploadId: file.clientUploadId,
        },
        signal,
        DIRECT_UPLOAD_ABORT_TIMEOUT_MS
      ).catch(() => {});
    }

    if (!isAbortError(error, signal)) {
      if (file.blob.size > SERVER_UPLOAD_MAX_BYTES) {
        return createJsonResponse(
          {
            error:
              "文件超过 50MB，必须使用浏览器直传；当前直传失败，请刷新后重试，或联系管理员检查存储桶 CORS/ETag 配置。",
            details: error instanceof Error ? error.message : String(error),
            clientUploadId: file.clientUploadId,
          },
          { status: 502 }
        );
      }

      console.warn("[Upload] Direct upload failed; falling back to server upload", error);
      suppressDirectUploadTemporarily();
      return null;
    }

    throw error;
  }
}

export async function fetchUploadWithRetry(
  formData: FormData,
  options?: {
    maxRetries?: number;
    signal?: AbortSignal;
    onProgress?: UploadProgressHandler;
  }
) {
  const maxRetries = options?.maxRetries ?? DEFAULT_MAX_RETRIES;

  return withUploadSlot(async () => {
    const directResponse = await fetchDirectUpload(
      formData,
      maxRetries,
      options?.signal,
      options?.onProgress
    );
    if (directResponse) {
      return directResponse;
    }

    const response = await fetchServerUploadWithRetry(
      formData,
      maxRetries,
      options?.signal,
      options?.onProgress
    );
    if (response.ok) {
      options?.onProgress?.({
        loaded: 1,
        total: 1,
        percent: 100,
        phase: "complete",
      });
    }
    return response;
  });
}