import { hc, type ClientRequestOptions } from 'hono/client'

import type * as App from './App.js'

/** Default hosted Tempo API URL. */
export const defaultUrl = 'https://api.tempo.xyz'

/** Creates a typed client for the hosted Tempo API. */
export function create(options: create.Options = {}): create.ReturnType {
  const { apiKey, url = defaultUrl, ...client } = options
  const mergedHeaders = headers(client.headers, apiKey)
  if (!mergedHeaders) return hc<App.App>(url, client)
  return hc<App.App>(url, { ...client, headers: mergedHeaders })
}

/** Typed Hono client for the Tempo API. */
export type Client = ReturnType<typeof hc<App.App>>

export declare namespace create {
  /** Typed Hono client returned by {@link create}. */
  type ReturnType = Client

  /** Options for creating a typed Tempo API client. */
  type Options = ClientRequestOptions & {
    /** API key sent on the canonical `tempo-api-key` header. */
    apiKey?: string | undefined
    /** Tempo API URL. Defaults to {@link defaultUrl}. */
    url?: string | undefined
  }
}

function headers(
  base: ClientRequestOptions['headers'],
  apiKey: string | undefined,
): ClientRequestOptions['headers'] {
  if (!apiKey) return base
  if (typeof base === 'function') return async () => mergeHeaders(await base(), apiKey)
  return mergeHeaders(base, apiKey)
}

function mergeHeaders(base: Record<string, string> | undefined, apiKey: string) {
  const headers = new Headers(base)
  headers.set('tempo-api-key', apiKey)
  return Object.fromEntries(headers.entries())
}