/**
 * src/platform/errors.ts
 * =======================
 * The canonical SIAX cross-product error vocabulary (Master-DoD §6), mirrored
 * from cl0ud's `packages/contract/src/request-context.ts` (`SIAX_ERROR_CODES`
 * + `httpStatusForSiaxErrorCode`) under the same documented mirror posture as
 * src/platform/siax-context.ts. tests/contracts/siax-context.contract.test.ts
 * pins the full code list and status mapping.
 *
 * `SiaxError` is the typed error every 0pt platform client and capability
 * service throws at a product boundary. Retryable vs permanent is explicit
 * (§6: "Retryable vs permanent är explicit"), correlation id travels in the
 * error (§6: "Correlation ID finns i felet"), and no sensitive internals are
 * embedded — `detail` is a short operator-facing string, never a raw body.
 */

export const SIAX_ERROR_CODES = [
  "UNAUTHENTICATED",
  "AUTHORIZATION_DENIED",
  "ENTITLEMENT_REQUIRED",
  "CAPABILITY_UNAVAILABLE",
  "QUOTA_EXCEEDED",
  "RATE_LIMITED",
  "INVALID_REQUEST",
  "NOT_FOUND",
  "CONFLICT",
  "DEPENDENCY_UNAVAILABLE",
  "RETRYABLE_FAILURE",
  "PERMANENT_FAILURE",
] as const;

/** One canonical SIAX error code. */
export type SiaxErrorCode = (typeof SIAX_ERROR_CODES)[number];

/** Canonical HTTP status for a {@link SiaxErrorCode} (transport guidance, pinned to cl0ud). */
export function httpStatusForSiaxErrorCode(code: SiaxErrorCode): number {
  switch (code) {
    case "UNAUTHENTICATED":
      return 401;
    case "AUTHORIZATION_DENIED":
      return 403;
    case "ENTITLEMENT_REQUIRED":
    case "QUOTA_EXCEEDED":
      return 402;
    case "CAPABILITY_UNAVAILABLE":
      return 404;
    case "RATE_LIMITED":
      return 429;
    case "INVALID_REQUEST":
      return 400;
    case "NOT_FOUND":
      return 404;
    case "CONFLICT":
      return 409;
    case "DEPENDENCY_UNAVAILABLE":
    case "RETRYABLE_FAILURE":
      return 503;
    case "PERMANENT_FAILURE":
      return 500;
    default: {
      const _never: never = code;
      return _never;
    }
  }
}

/** Whether a caller may retry the failed operation (with its idempotency key). */
export function isRetryableSiaxErrorCode(code: SiaxErrorCode): boolean {
  return code === "DEPENDENCY_UNAVAILABLE" || code === "RETRYABLE_FAILURE" || code === "RATE_LIMITED";
}

/** Map an upstream HTTP status (from a SIAX dependency) onto the canonical vocabulary. */
export function siaxErrorCodeForUpstreamStatus(status: number): SiaxErrorCode {
  if (status === 400) return "INVALID_REQUEST";
  if (status === 401) return "UNAUTHENTICATED";
  if (status === 402) return "ENTITLEMENT_REQUIRED";
  if (status === 403) return "AUTHORIZATION_DENIED";
  if (status === 404) return "NOT_FOUND";
  if (status === 409) return "CONFLICT";
  if (status === 429) return "RATE_LIMITED";
  if (status === 501) return "CAPABILITY_UNAVAILABLE";
  if (status === 502 || status === 503 || status === 504) return "DEPENDENCY_UNAVAILABLE";
  if (status >= 500) return "RETRYABLE_FAILURE";
  return "PERMANENT_FAILURE";
}

/** The typed error thrown at 0pt product boundaries. */
export class SiaxError extends Error {
  readonly code: SiaxErrorCode;
  /** Which dependency/capability produced the failure, e.g. "st0re", "0pt.search.query". */
  readonly source: string;
  /** Correlation id of the failing operation, when known (§6). */
  readonly correlationId?: string;
  readonly retryable: boolean;
  readonly httpStatus: number;

  constructor(
    code: SiaxErrorCode,
    source: string,
    detail: string,
    opts?: { correlationId?: string; cause?: unknown }
  ) {
    super(`[${code}] ${source}: ${detail}`, { cause: opts?.cause });
    this.name = "SiaxError";
    this.code = code;
    this.source = source;
    this.correlationId = opts?.correlationId;
    this.retryable = isRetryableSiaxErrorCode(code);
    this.httpStatus = httpStatusForSiaxErrorCode(code);
  }

  /** Structured log/JSON form. Never includes stack or raw upstream bodies. */
  toJSON(): Record<string, unknown> {
    return {
      error: this.code,
      source: this.source,
      message: this.message,
      retryable: this.retryable,
      ...(this.correlationId ? { correlation_id: this.correlationId } : {}),
    };
  }
}