/**
 * Suno API HTTP client with rate limiting, proxy support, retries and polling helpers.
 *
 * Rate limit: 20 requests per 10 seconds (sunoapi.org).
 * Proxy support via SUNO_HTTP_PROXY / HTTPS_PROXY / HTTP_PROXY env vars.
 */

import { fetch, ProxyAgent } from 'undici';

export interface SunoApiResponse<T = unknown> {
  code: number;
  msg: string;
  data: T;
}

export interface SunoTrack {
  id: string;
  audio_url?: string;
  audioUrl?: string;
  source_audio_url?: string;
  stream_audio_url?: string;
  streamAudioUrl?: string;
  source_stream_audio_url?: string;
  image_url?: string;
  imageUrl?: string;
  source_image_url?: string;
  prompt?: string;
  model_name?: string;
  modelName?: string;
  title?: string;
  tags?: string;
  createTime?: string;
  duration?: number;
}

export interface SunoLyricsVariant {
  text?: string;
  title?: string;
  status?: string;
  errorMessage?: string;
}

export interface SunoTaskData {
  taskId: string;
  parentMusicId?: string;
  param?: string;
  response?: {
    taskId?: string;
    data?: SunoTrack[] | SunoLyricsVariant[];
    sunoData?: SunoTrack[];
  };
  status: string;
  type?: string;
  operationType?: 'generate' | 'extend' | 'upload_cover' | 'upload_extend';
  errorCode?: number | null;
  errorMessage?: string | null;
}

function getProxyUrl(): string | undefined {
  return (
    process.env.SUNO_HTTP_PROXY ||
    process.env.HTTPS_PROXY ||
    process.env.https_proxy ||
    process.env.HTTP_PROXY ||
    process.env.http_proxy
  );
}

function isRetryableError(error: unknown): boolean {
  if (error instanceof Error) {
    const msg = error.message.toLowerCase();
    return msg.includes('timeout') || msg.includes('econnreset') || msg.includes('socket') || msg.includes('fetch failed');
  }
  return false;
}

function sleep(ms: number): Promise<void> {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

export class SunoClient {
  private readonly baseUrl = 'https://api.sunoapi.org/api/v1';
  private readonly apiKey: string;
  private readonly maxRequests = 20;
  private readonly windowMs = 10_000;
  private readonly proxyAgent?: ProxyAgent;
  private readonly requestTimeoutMs = 30_000;
  private readonly maxRetries = 2;
  private requestTimestamps: number[] = [];

  constructor(apiKey: string) {
    this.apiKey = apiKey;
    const proxyUrl = getProxyUrl();
    if (proxyUrl) {
      this.proxyAgent = new ProxyAgent(proxyUrl);
    }
  }

  /**
   * Enforce rate limit: max 20 requests per 10 seconds.
   */
  private async throttle(): Promise<void> {
    while (true) {
      const now = Date.now();
      this.requestTimestamps = this.requestTimestamps.filter((ts) => now - ts < this.windowMs);

      if (this.requestTimestamps.length < this.maxRequests) {
        this.requestTimestamps.push(now);
        return;
      }

      const oldest = this.requestTimestamps[0];
      const wait = Math.max(0, this.windowMs - (now - oldest));
      await sleep(wait);
    }
  }

  async request<T = unknown>(
    method: 'GET' | 'POST',
    path: string,
    body?: Record<string, unknown>
  ): Promise<SunoApiResponse<T>> {
    await this.throttle();

    const url = path.startsWith('http') ? path : `${this.baseUrl}${path}`;
    const headers: Record<string, string> = {
      Authorization: `Bearer ${this.apiKey}`,
      'Content-Type': 'application/json',
    };

    let lastError: Error | undefined;
    for (let attempt = 0; attempt <= this.maxRetries; attempt++) {
      try {
        const fetchOptions: RequestInit & { dispatcher?: ProxyAgent } = {
          method,
          headers,
          body: body ? JSON.stringify(body) : undefined,
          signal: AbortSignal.timeout(this.requestTimeoutMs),
        };
        if (this.proxyAgent) {
          fetchOptions.dispatcher = this.proxyAgent;
        }

        const response = await fetch(url, fetchOptions);
        const text = await response.text();

        let json: SunoApiResponse<T>;
        try {
          json = JSON.parse(text) as SunoApiResponse<T>;
        } catch {
          throw new Error(`Invalid JSON response from Suno API: ${text}`);
        }

        // Retry on transient server errors / rate-limit before throwing.
        if (json.code === 429 || json.code === 503 || json.code === 504) {
          if (attempt < this.maxRetries) {
            const backoff = Math.min(1000 * 2 ** attempt, 8000);
            await sleep(backoff);
            continue;
          }
        }

        if (json.code !== 200) {
          throw new Error(`Suno API error ${json.code}: ${json.msg || 'unknown error'}`);
        }

        return json;
      } catch (error: unknown) {
        lastError = error instanceof Error ? error : new Error(String(error));
        const retryable = isRetryableError(lastError);
        if (retryable && attempt < this.maxRetries) {
          const backoff = Math.min(1000 * 2 ** attempt, 8000);
          await sleep(backoff);
          continue;
        }
        throw lastError;
      }
    }

    throw lastError ?? new Error('Suno API request failed');
  }

  get<T = unknown>(path: string): Promise<SunoApiResponse<T>> {
    return this.request<T>('GET', path);
  }

  post<T = unknown>(path: string, body: Record<string, unknown>): Promise<SunoApiResponse<T>> {
    return this.request<T>('POST', path, body);
  }

  /**
   * Poll task status until terminal state or timeout.
   */
  async pollTaskStatus(
    taskId: string,
    options: {
      intervalMs?: number;
      maxAttempts?: number;
      statusPath?: string;
    } = {}
  ): Promise<SunoTaskData> {
    const intervalMs = options.intervalMs ?? 15_000;
    const maxAttempts = options.maxAttempts ?? 60;
    const statusPath = options.statusPath ?? `/generate/record-info?taskId=${encodeURIComponent(taskId)}`;

    for (let attempt = 1; attempt <= maxAttempts; attempt++) {
      const result = await this.get<SunoTaskData>(statusPath);
      const status = result.data.status;

      if (
        status === 'SUCCESS' ||
        status === 'FAILED' ||
        status === 'CREATE_TASK_FAILED' ||
        status === 'GENERATE_AUDIO_FAILED' ||
        status === 'GENERATE_LYRICS_FAILED' ||
        status === 'CALLBACK_EXCEPTION' ||
        status === 'SENSITIVE_WORD_ERROR'
      ) {
        return result.data;
      }

      if (attempt < maxAttempts) {
        await sleep(intervalMs);
      }
    }

    throw new Error(`Polling timeout for task ${taskId} after ${maxAttempts} attempts`);
  }
}