import type { FetchContext } from '../types'

export interface EapiRequestConfig {
  url: string
  method?: 'GET' | 'POST' | 'PUT' | 'DELETE' | 'PATCH'
  params?: Record<string, unknown>
  body?: unknown
  data?: unknown
  headers?: Record<string, string>
}

export interface EapiClient {
  request: <T>(config: EapiRequestConfig) => Promise<T>
}

export interface EapiAdapterOptions {
  /** Called before each request to inject dynamic headers (e.g. auth tokens) */
  getHeaders?: () => Record<string, string>
  /** Called after each response with the response headers */
  onResponse?: (headers: Record<string, string>) => void
}

export function createEapiAdapter(
  client: EapiClient,
  options?: EapiAdapterOptions,
) {
  async function fetchConfig(config: EapiRequestConfig): Promise<unknown> {
    const headers = {
      ...config.headers,
      ...(options?.getHeaders?.() ?? {}),
    }

    const requestConfig: EapiRequestConfig = {
      ...config,
      // Map 'body' to 'data' for axios compatibility
      data: config.body ?? config.data,
      headers,
    }

    const response = await client.request(requestConfig)

    // Call onResponse callback with response headers if provided
    if (options?.onResponse && (response as Record<string, unknown>)?.headers) {
      options.onResponse(
        (response as Record<string, unknown>).headers as Record<string, string>,
      )
    }

    // Extract data from axios response wrapper
    return (response as Record<string, unknown>)?.data ?? response
  }

  return {
    /** Directly call the EAPI client with a static config */
    fetch: fetchConfig,

    /**
     * Returns a SourceDescriptor-compatible fetch function that merges the
     * base config with dynamic params passed via engine.trigger(key, { params }).
     */
    createFetch:
      (baseConfig: EapiRequestConfig) =>
      (ctx: FetchContext): Promise<unknown> => {
        const merged: EapiRequestConfig = {
          ...baseConfig,
          params: { ...baseConfig.params, ...ctx.options.params },
        }
        return fetchConfig(merged)
      },
  }
}