import { StudioGatewayError } from "../../application/ports/studio-gateway-error.ts";
import type { UploadAssetForm } from "../../application/ports/studio-asset-gateway.ts";
import type { Asset, ProblemDetails } from "../../contracts/studio/contract.ts";
import { envelopeData, envelopeError } from "../../contracts/tech-log-studio-contract-contribution.ts";
import type { StudioAssetUploadTransport } from "./http-studio-asset-gateway.ts";
import { STUDIO_ERROR_CODES } from "./studio-error-mapping.ts";

const CODES = new Set<string>(STUDIO_ERROR_CODES);

/**
 * canonical `uploadStudioAsset`도 다른 18개 operation과 같은 봉투(ADR-006)를
 * 쓴다 — 이 seam만 일반 계약 런타임을 안 거칠 뿐이지 wire format은 같다.
 * 그래서 `tech-log-studio-contract-contribution.ts`의 언랩 validator를 그대로
 * 재사용한다: 봉투 뼈대 검증 로직이 두 곳에서 따로 드리프트하는 것을 막는다.
 */
const UPLOAD_DATA = envelopeData<Asset>("uploadStudioAssetOutput");
const UPLOAD_PROBLEM = envelopeError();

/**
 * The contract runtime can only express `requestBody: "NONE" | "JSON"` and the
 * low-level client always serializes the body as JSON (see
 * `external-contract-runtime.ts` and `client.ts:719`). The canonical
 * `POST /assets` is multipart, so this one operation is split into a narrow
 * seam instead. If upload moves to presigned/resumable transfer, or the
 * platform grows a MULTIPART mode, only this file is replaced.
 */
export function createAssetUploadTransport(
  deps: Readonly<{
    baseUrl: string;
    timeoutMs: number;
    fetch?: typeof globalThis.fetch;
  }>,
): StudioAssetUploadTransport {
  const doFetch = deps.fetch ?? globalThis.fetch.bind(globalThis);
  const endpoint = new URL("api/v1/studio/assets", deps.baseUrl).href;

  function unavailable(
    detail: string,
    options?: Readonly<{ status?: number; retryable?: boolean }>,
  ): StudioGatewayError {
    return new StudioGatewayError({
      type: "https://techlog.local/problems/studio-unavailable",
      title: "STUDIO_UNAVAILABLE",
      status: options?.status ?? 503,
      detail,
      code: "STUDIO_UNAVAILABLE",
      retryable: options?.retryable ?? true,
    });
  }

  return Object.freeze({
    async upload(form: UploadAssetForm, headers, options) {
      const body = new FormData();
      body.append("file", form.file, form.file.name);
      body.append("kind", form.kind);
      if (form.altText !== undefined) body.append("altText", form.altText);
      if (form.decorative !== undefined) body.append("decorative", String(form.decorative));

      const timeout = AbortSignal.timeout(deps.timeoutMs);
      const signal = options?.signal
        ? AbortSignal.any([options.signal, timeout])
        : timeout;

      let response: Response;
      try {
        // content-type is never set by hand here. fetch generates the
        // multipart boundary; setting it manually produces a body the server
        // cannot parse.
        response = await doFetch(endpoint, {
          method: "POST",
          headers: { ...headers },
          body,
          signal,
          credentials: "include",
        });
      } catch (error) {
        if (signal.aborted) {
          // M3 (fix round 1). Align with the JSON path's `CANCELLED` mapping
          // (`toStudioGatewayError` maps it to `STUDIO_UNAVAILABLE` / 499 /
          // `retryable: false`) — a caller-cancelled or deadline-exceeded
          // upload is not a retryable outage, so it must not carry
          // `retryable: true` the way a genuine transport failure does.
          throw unavailable("Upload was aborted before it completed.", {
            status: 499,
            retryable: false,
          });
        }
        throw unavailable(
          error instanceof Error ? `Upload transport failed: ${error.message}` : "Upload transport failed.",
        );
      }

      if (response.status === 201 || response.status === 200) {
        let body: unknown;
        try {
          body = await response.json();
        } catch {
          // M1 (fix round 1). This port's contract is `StudioGatewayError`;
          // a malformed success body must not throw a raw `SyntaxError` out
          // of it.
          throw unavailable(
            `Upload returned status ${response.status} with a body that could not be parsed as JSON.`,
          );
        }
        const parsed = UPLOAD_DATA.safeParse(body);
        if (!parsed.success) {
          // 봉투 뼈대(`{success:true, data, meta}`)가 아니다 — payload는
          // 통과시키되 봉투 자체는 반드시 검증한다(다른 18개 operation과 동일
          // 원칙, ADR-006).
          throw unavailable(
            `Upload returned status ${response.status} with a body that did not match the response envelope.`,
          );
        }
        return parsed.data;
      }

      let problemBody: unknown = null;
      try {
        problemBody = await response.json();
      } catch {
        problemBody = null;
      }
      const parsedProblem = problemBody === null ? null : UPLOAD_PROBLEM.safeParse(problemBody);
      if (parsedProblem && parsedProblem.success && CODES.has(parsedProblem.data.code)) {
        // `studio-error-mapping.ts`의 PROBLEM 분기와 같은 캐스트: 봉투는 이미
        // `code`를 `apiErrorSchema`의 enum으로 검증했으므로(`CODES.has` 확인도
        // 통과) `ProblemDetails["code"]`로 좁혀도 안전하다. envelope에는 HTTP
        // status가 없다 (`envelopeError`가 0으로 둔다) — 이 seam은 실제 status를
        // 이미 들고 있으므로 바로 덮는다.
        const problem = parsedProblem.data as unknown as ProblemDetails;
        throw new StudioGatewayError({ ...problem, status: response.status });
      }
      // Fix round 2, item 2. The real status is passed through (not the
      // hardcoded 503 default) so `http-studio-asset-gateway.ts`'s
      // `error.status === 401 || error.status === 403` check can still act on
      // an uncontracted 401/403 body and invalidate the cached CSRF token.
      throw unavailable(`Upload returned an uncontracted status ${response.status}.`, {
        status: response.status,
      });
    },
  });
}