import { FEED_BASE_URL } from "./env";
import { MAX_POST_LENGTH } from "./post-create";
import { ensureFreshSession, refreshSession, type RefreshOptions } from "./session-refresh";
import type { SessionData } from "./session-store";

// Media-post creation proxy. Unlike a text post this needs five feed steps:
//   1. create an image/video draft
//   2. ask the feed for a presigned upload URL
//   3. the SERVER PUTs the bytes to that URL (the browser never gets the token)
//   4. confirm the upload (image confirmation blocks until processing finishes)
//   5. publish with the same {content} publish call as a text post
// The pipeline is media-type agnostic; the allowed-type gates and entry points
// (createImagePost, createVideoPost) are per kind.
// Neither the feed token nor the file bytes are ever logged.

export type MediaKind = "image" | "video";

/** Image content types the feed accepts (spec: "Create a post with an image or video"). */
export const ALLOWED_IMAGE_TYPES: readonly string[] = [
  "image/jpeg",
  "image/jpg",
  "image/png",
  "image/gif",
  "image/webp",
  "image/heic",
];

/** Video content types the feed accepts. */
export const ALLOWED_VIDEO_TYPES: readonly string[] = ["video/mp4", "video/quicktime", "video/webm"];

/** Upper bound on an uploaded video, enforced before any feed call. */
export const MAX_VIDEO_BYTES = 200 * 1024 * 1024;

/** Upper bound on an uploaded image, enforced before any feed call. */
export const MAX_IMAGE_BYTES = 15 * 1024 * 1024;

export type CreateMediaPostResult =
  | { ok: true; id: string; status: string | null }
  | {
      ok: false;
      status: 400 | 401 | 502;
      error: "sign_in" | "too_long" | "bad_file" | "post_failed";
    };

export interface MediaUpload {
  /** The file to upload. */
  file: { name: string; type: string; size: number; arrayBuffer: () => Promise<ArrayBuffer> };
  /** Draft type and confirm mediaType. */
  mediaType: MediaKind;
}

type Fetch = typeof fetch;

function rec(v: unknown): Record<string, unknown> {
  return v && typeof v === "object" && !Array.isArray(v) ? (v as Record<string, unknown>) : {};
}

function str(v: unknown): string | undefined {
  return typeof v === "string" && v.length > 0 ? v : undefined;
}

function readCreated(body: unknown): { id: string; status: string | null } | null {
  const root = rec(body);
  const data = rec(root.data);
  const post = rec(data.post);
  for (const v of [data.id, post.id, root.id]) {
    if ((typeof v === "string" && v) || typeof v === "number") {
      const status = [data.status, post.status, root.status].find((s) => typeof s === "string");
      return { id: String(v), status: (status as string | undefined) ?? null };
    }
  }
  return null;
}

/** Tolerant reader for the presigned-urls response (field names are not pinned by the spec). */
function readPresigned(
  body: unknown,
): { uploadUrl: string; attachmentId: string; s3Key: string } | null {
  const root = rec(body);
  const data = root.data;
  // The entry may be the first element of an array, the first element of a
  // named list, or the data object itself.
  const candidates: unknown[] = [];
  if (Array.isArray(data)) candidates.push(...data);
  else if (Array.isArray(body)) candidates.push(...(body as unknown[]));
  else {
    const d = rec(data);
    for (const key of ["files", "urls", "attachments", "presignedUrls"]) {
      if (Array.isArray(d[key])) candidates.push(...(d[key] as unknown[]));
    }
    candidates.push(d);
  }
  for (const c of candidates) {
    const e = rec(c);
    const uploadUrl =
      str(e.uploadUrl) ?? str(e.url) ?? str(e.presignedUrl) ?? str(e.signedUrl) ?? str(e.putUrl);
    const attachmentId = str(e.attachmentId) ?? str(e.id);
    const s3Key = str(e.s3Key) ?? str(e.key) ?? str(e.objectKey);
    if (uploadUrl && attachmentId && s3Key) return { uploadUrl, attachmentId, s3Key };
  }
  return null;
}

function sendJson(token: string, path: string, payload: unknown, doFetch: Fetch) {
  return doFetch(`${FEED_BASE_URL}${path}`, {
    method: "POST",
    headers: {
      Accept: "application/json",
      "Content-Type": "application/json",
      Authorization: `Bearer ${token}`,
    },
    body: JSON.stringify(payload),
  });
}

/** True when the type is an accepted image content type (case-insensitive). */
export function isAllowedImageType(type: string): boolean {
  return ALLOWED_IMAGE_TYPES.includes(type.trim().toLowerCase());
}

/** True when the type is an accepted video content type (case-insensitive). */
export function isAllowedVideoType(type: string): boolean {
  return ALLOWED_VIDEO_TYPES.includes(type.trim().toLowerCase());
}

/**
 * Create a public video post: same pipeline as an image with type "video".
 * Video confirmation may return while transcoding continues; the post is
 * published anyway and the card shows the thumbnail until hlsUrl appears.
 */
export async function createVideoPost(
  sessionId: string | undefined,
  content: unknown,
  file: MediaUpload["file"] | null,
  options: RefreshOptions = {},
): Promise<CreateMediaPostResult> {
  if (!file || typeof file.size !== "number" || file.size <= 0 || file.size > MAX_VIDEO_BYTES) {
    return { ok: false, status: 400, error: "bad_file" };
  }
  if (typeof file.type !== "string" || !isAllowedVideoType(file.type)) {
    return { ok: false, status: 400, error: "bad_file" };
  }
  return runMediaPipeline(sessionId, content, { file, mediaType: "video" }, options);
}

/** Route entry point: picks image or video from the file type; anything else is a 400. */
export async function createMediaPost(
  sessionId: string | undefined,
  content: unknown,
  file: MediaUpload["file"] | null,
  options: RefreshOptions = {},
): Promise<CreateMediaPostResult> {
  if (file && typeof file.type === "string" && isAllowedVideoType(file.type)) {
    return createVideoPost(sessionId, content, file, options);
  }
  return createImagePost(sessionId, content, file, options);
}

/**
 * Create a public image post from a caption and one file: draft -> presigned URL
 * -> server-side PUT -> confirm -> publish. Returns the post id so the caller can
 * confirm it on the reloaded first page. The video task reuses `runMediaPipeline`
 * with `mediaType: "video"` and its own type gate.
 */
export async function createImagePost(
  sessionId: string | undefined,
  content: unknown,
  file: MediaUpload["file"] | null,
  options: RefreshOptions = {},
): Promise<CreateMediaPostResult> {
  if (!file || typeof file.size !== "number" || file.size <= 0 || file.size > MAX_IMAGE_BYTES) {
    return { ok: false, status: 400, error: "bad_file" };
  }
  if (typeof file.type !== "string" || !isAllowedImageType(file.type)) {
    return { ok: false, status: 400, error: "bad_file" };
  }
  return runMediaPipeline(sessionId, content, { file, mediaType: "image" }, options);
}

/**
 * Media-type agnostic upload-and-publish pipeline. Callers validate the file
 * first (type, size) for their media kind. A caption may be empty for a media
 * post; only an over-length caption is rejected.
 */
export async function runMediaPipeline(
  sessionId: string | undefined,
  content: unknown,
  upload: MediaUpload,
  options: RefreshOptions = {},
): Promise<CreateMediaPostResult> {
  const signIn = { ok: false, status: 401, error: "sign_in" } as const;
  const failed = { ok: false, status: 502, error: "post_failed" } as const;
  const doFetch = options.fetchImpl ?? fetch;
  const { file, mediaType } = upload;

  let session: SessionData | null = await ensureFreshSession(sessionId, options);
  if (!session || !sessionId) return signIn;

  const caption = typeof content === "string" ? content : "";
  if (caption.length > MAX_POST_LENGTH) {
    return { ok: false, status: 400, error: "too_long" };
  }

  // One feed call with a single refresh-and-retry on a 401 token rejection.
  const call = async (path: string, payload: unknown): Promise<Response | "sign_in"> => {
    let res = await sendJson(session!.feedAccessToken, path, payload, doFetch);
    if (res.status === 401) {
      session = await refreshSession(sessionId, options);
      if (!session) return "sign_in";
      res = await sendJson(session.feedAccessToken, path, payload, doFetch);
      if (res.status === 401) return "sign_in";
    }
    return res;
  };

  try {
    // 1. Draft.
    const created = await call("/api/v1/posts", {
      content: caption,
      type: mediaType,
      status: "draft",
      visibility: "public",
    });
    if (created === "sign_in") return signIn;
    if (created.status !== 200 && created.status !== 201) return failed;
    const info = readCreated(await created.json().catch(() => null));
    if (!info) return failed;

    // 2. Presigned URL for the one file.
    const presignedRes = await call("/api/v1/attachments/presigned-urls", {
      postId: info.id,
      files: [{ name: file.name, type: file.type, size: file.size }],
    });
    if (presignedRes === "sign_in") return signIn;
    if (presignedRes.status < 200 || presignedRes.status > 299) return failed;
    const slot = readPresigned(await presignedRes.json().catch(() => null));
    if (!slot) return failed;

    // 3. The server PUTs the bytes. No Authorization header: the presigned URL
    // is pre-authorized, and the feed token must never reach S3 or the browser.
    const bytes = await file.arrayBuffer();
    const put = await doFetch(slot.uploadUrl, {
      method: "PUT",
      headers: { "Content-Type": file.type },
      body: bytes,
    });
    if (!put.ok) return failed;

    // 4. Confirm (image confirmation blocks until processing finishes).
    const confirmed = await call("/api/v1/attachments/confirm-uploads", {
      postId: info.id,
      uploads: [
        {
          attachmentId: slot.attachmentId,
          s3Key: slot.s3Key,
          mediaType,
          filename: file.name,
        },
      ],
    });
    if (confirmed === "sign_in") return signIn;
    if (confirmed.status < 200 || confirmed.status > 299) return failed;

    // 5. Publish, same call as a text post.
    const published = await call(`/api/v1/posts/${encodeURIComponent(info.id)}/publish`, {
      content: caption,
    });
    if (published === "sign_in") return signIn;
    if (published.status < 200 || published.status > 299) return failed;

    return { ok: true, id: info.id, status: info.status };
  } catch {
    return failed;
  }
}