export interface ThreeCxConfig {
  domain: string;
  clientId: string;
  clientSecret: string;
}

export class ThreeCxClient {
  private accessToken: string | undefined;
  private readonly baseUrl: string;

  constructor(private readonly config: ThreeCxConfig) {
    this.baseUrl = `https://${config.domain.replace(/^https?:\/\//, "")}`;
  }

  async getAccessToken(): Promise<string> {
    if (this.accessToken) {
      return this.accessToken;
    }
    const res = await fetch(`${this.baseUrl}/connect/token`, {
      method: "POST",
      headers: { "Content-Type": "application/x-www-form-urlencoded" },
      body: new URLSearchParams({
        grant_type: "client_credentials",
        client_id: this.config.clientId,
        client_secret: this.config.clientSecret,
      }),
    });
    if (!res.ok) {
      throw new Error(`3CX token request failed: ${res.status}`);
    }
    const body = (await res.json()) as { access_token?: string };
    if (!body.access_token) {
      throw new Error("3CX token response missing access_token");
    }
    this.accessToken = body.access_token;
    return this.accessToken;
  }

  async getJson<T>(path: string): Promise<{ status: number; body: T }> {
    const token = await this.getAccessToken();
    const res = await fetch(`${this.baseUrl}${path}`, {
      headers: { Authorization: `Bearer ${token}`, Accept: "application/json" },
    });
    const text = await res.text();
    const body = (text ? JSON.parse(text) : {}) as T;
    return { status: res.status, body };
  }

  async patchJson<T>(path: string, payload: unknown): Promise<{ status: number; body: T }> {
    const token = await this.getAccessToken();
    const res = await fetch(`${this.baseUrl}${path}`, {
      method: "PATCH",
      headers: {
        Authorization: `Bearer ${token}`,
        Accept: "application/json",
        "Content-Type": "application/json",
      },
      body: JSON.stringify(payload),
    });
    const text = await res.text();
    const body = (text ? JSON.parse(text) : {}) as T;
    return { status: res.status, body };
  }

  async listUsers<T>(): Promise<T[]> {
    const users: T[] = [];
    let path =
      "/xapi/v1/Users?$top=100&$select=Id,Number,FirstName,LastName,Blfs,PrimaryGroupId&$expand=Groups($select=Id,Name),Phones";
    for (let i = 0; i < 20; i++) {
      const page = await this.getJson<{ value?: T[]; "@odata.nextLink"?: string }>(path);
      if (page.status !== 200) {
        throw new Error(`3CX Users list failed: ${page.status}`);
      }
      users.push(...(page.body.value ?? []));
      const next = page.body["@odata.nextLink"];
      if (!next) {
        break;
      }
      path = next.replace(this.baseUrl, "");
    }
    return users;
  }

  async getPeerByNumber(number: string): Promise<{ Id: number; Number: string; Name?: string } | undefined> {
    const encoded = number.replace(/'/g, "''");
    const page = await this.getJson<{ value?: Array<{ Id: number; Number: string; Name?: string }> }>(
      `/xapi/v1/Peers?$filter=Number eq '${encoded}'&$top=1`
    );
    if (page.status !== 200) {
      return undefined;
    }
    return page.body.value?.[0];
  }

  async patchUserBlfs(userId: number, blfs: string): Promise<{ status: number }> {
    const path = `/xapi/v1/Users(${userId})`;
    const current = await this.getJson<Record<string, unknown>>(path);
    if (current.status !== 200) {
      return { status: current.status };
    }
    const payload = { ...current.body };
    delete payload["@odata.context"];
    payload.Blfs = blfs;
    const patched = await this.patchJson<Record<string, unknown>>(path, payload);
    return { status: patched.status };
  }
}