import { randomUUID } from "node:crypto";
import type { Context } from "hono";
import type { ContentfulStatusCode } from "hono/utils/http-status";

export type ErrorCode =
  | "UNAUTHENTICATED"
  | "FORBIDDEN"
  | "NOT_FOUND"
  | "VALIDATION_ERROR"
  | "CONFLICT"
  | "INTERNAL_ERROR"
  | "DATABASE_UNAVAILABLE";

export class ApiError extends Error {
  constructor(
    readonly status: ContentfulStatusCode,
    readonly code: ErrorCode,
    message: string,
  ) {
    super(message);
    this.name = "ApiError";
  }
}

export const CORRELATION_HEADER = "x-correlation-id";

export type ErrorEnvelope = {
  error: {
    code: ErrorCode;
    message: string;
    correlationId: string;
  };
};

export function correlationIdFrom(c: Context): string {
  const raw = c.req.header(CORRELATION_HEADER)?.trim();
  if (raw && raw.length <= 128) {
    return raw;
  }
  return randomUUID();
}

export function errorBody(code: ErrorCode, message: string, correlationId: string): ErrorEnvelope {
  return { error: { code, message, correlationId } };
}

export function errorJson(
  c: Context,
  status: ContentfulStatusCode,
  code: ErrorCode,
  message: string,
  correlationId?: string,
) {
  const id = correlationId ?? correlationIdFrom(c);
  c.header(CORRELATION_HEADER, id);
  return c.json(errorBody(code, message, id), status);
}