import type {
  ApiErrorPayload,
  Organization,
  OrganizationDetailParams,
  OrganizationListParams,
  OrganizationListResponse,
  QueryListValue,
  JsonValue,
} from "./types.js";

export type FetchLike = (
  input: RequestInfo,
  init?: RequestInit,
) => Promise<Response>;

export interface MostovikOrganizationsClientOptions {
  baseUrl: string | URL;
  fetch?: FetchLike;
  headers?: HeadersInit;
  accessToken?: string;
}

export interface ApiRequestOptions {
  headers?: HeadersInit;
  signal?: AbortSignal;
}

export class ApiClientError extends Error {
  readonly status: number;
  readonly payload: ApiErrorPayload;

  constructor(message: string, status: number, payload: ApiErrorPayload) {
    super(message);
    this.name = "ApiClientError";
    this.status = status;
    this.payload = payload;
  }
}

type QueryParamValue = string | number | boolean | null | undefined;
type QueryParam = QueryParamValue | readonly QueryParamValue[];
type QueryParams = Record<string, QueryParam>;

export class MostovikOrganizationsClient {
  private readonly baseUrl: string;
  private readonly fetchImpl: FetchLike;
  private readonly defaultHeaders: HeadersInit | undefined;
  private readonly accessToken: string | undefined;

  constructor(options: MostovikOrganizationsClientOptions) {
    this.baseUrl = normalizeBaseUrl(options.baseUrl);
    this.fetchImpl = options.fetch ?? defaultFetch();
    this.defaultHeaders = options.headers;
    this.accessToken = options.accessToken;
  }

  listOrganizations(
    params: OrganizationListParams = {},
    options: ApiRequestOptions = {},
  ): Promise<OrganizationListResponse> {
    return this.request<OrganizationListResponse>(
      "api/v2/organizations/",
      params as QueryParams,
      options,
    );
  }

  getOrganization(
    uid: string,
    params: OrganizationDetailParams = {},
    options: ApiRequestOptions = {},
  ): Promise<Organization> {
    return this.request<Organization>(
      `api/v2/organizations/${encodeURIComponent(uid)}/`,
      params as QueryParams,
      options,
    );
  }

  private async request<T>(
    path: string,
    params: QueryParams,
    options: ApiRequestOptions,
  ): Promise<T> {
    const url = this.buildUrl(path, params);
    const init: RequestInit = {
      method: "GET",
      headers: this.buildHeaders(options.headers),
    };
    if (options.signal !== undefined) {
      init.signal = options.signal;
    }

    const response = await this.fetchImpl(url.toString(), init);
    const payload = await parseResponsePayload(response);

    if (!response.ok) {
      const errorPayload = toApiErrorPayload(payload, response.status);
      throw new ApiClientError(
        `GET ${url.pathname} failed with HTTP ${response.status}`,
        response.status,
        errorPayload,
      );
    }

    return payload as T;
  }

  private buildUrl(path: string, params: QueryParams): URL {
    const url = new URL(path, this.baseUrl);
    appendQueryParams(url, params);
    return url;
  }

  private buildHeaders(requestHeaders?: HeadersInit): Headers {
    const headers = new Headers(this.defaultHeaders);
    headers.set("Accept", "application/json");

    if (this.accessToken !== undefined && !headers.has("Authorization")) {
      headers.set("Authorization", `Bearer ${this.accessToken}`);
    }

    if (requestHeaders !== undefined) {
      new Headers(requestHeaders).forEach((value, key) => {
        headers.set(key, value);
      });
    }

    return headers;
  }
}

function normalizeBaseUrl(baseUrl: string | URL): string {
  const value = String(baseUrl);
  return value.endsWith("/") ? value : `${value}/`;
}

function defaultFetch(): FetchLike {
  if (typeof globalThis.fetch !== "function") {
    throw new Error(
      "No fetch implementation is available. Pass fetch in client options.",
    );
  }

  return (input, init) => globalThis.fetch(input, init);
}

function appendQueryParams(url: URL, params: QueryParams): void {
  Object.entries(params).forEach(([key, value]) => {
    if (isQueryParamArray(value)) {
      value.forEach((item) => appendQueryParam(url, key, item));
      return;
    }

    appendQueryParam(url, key, value);
  });
}

function isQueryParamArray(value: QueryParam): value is readonly QueryParamValue[] {
  return Array.isArray(value);
}

function appendQueryParam(url: URL, key: string, value: QueryParamValue): void {
  if (value === undefined || value === null) {
    return;
  }

  url.searchParams.append(key, String(value));
}

async function parseResponsePayload(response: Response): Promise<JsonValue | null> {
  const contentType = response.headers.get("content-type") ?? "";
  const body = await response.text();
  if (body === "") {
    return null;
  }

  if (contentType.includes("application/json")) {
    return JSON.parse(body) as JsonValue;
  }

  try {
    return JSON.parse(body) as JsonValue;
  } catch {
    return body;
  }
}

function toApiErrorPayload(
  payload: JsonValue | null,
  status: number,
): ApiErrorPayload {
  if (
    isJsonObject(payload) &&
    payload.success === false &&
    payload.data === null &&
    Array.isArray(payload.errors)
  ) {
    const meta = payload.meta ?? null;
    return {
      success: false,
      data: null,
      errors: payload.errors.map(toApiErrorDetail),
      meta: isJsonObject(meta) ? meta : null,
    };
  }

  return {
    success: false,
    data: null,
    errors: [
      {
        code: `http_${status}`,
        message: "HTTP request failed",
        details: {
          payload,
        },
      },
    ],
    meta: null,
  };
}

function toApiErrorDetail(value: JsonValue): {
  code: string;
  message: string;
  details?: { readonly [key: string]: JsonValue };
} {
  if (isJsonObject(value)) {
    const details = value.details ?? null;
    const code = typeof value.code === "string" ? value.code : "error";
    const message =
      typeof value.message === "string" ? value.message : JSON.stringify(value);
    if (isJsonObject(details)) {
      return {
        code,
        message,
        details,
      };
    }
    return {
      code,
      message,
    };
  }

  return {
    code: "error",
    message: String(value),
  };
}

function isJsonObject(value: JsonValue | null): value is {
  readonly [key: string]: JsonValue;
} {
  return typeof value === "object" && value !== null && !Array.isArray(value);
}