/**
 * Example client for integrating with the Hono proxy from Next.js
 * Place this in your Next.js app at: lib/api-client.ts
 */

const API_URL = process.env.NEXT_PUBLIC_API_URL || 'http://localhost:4000/api';

export interface SearchResult {
  root: {
    children: Array<{
      id: string;
      relevance: number;
      fields: {
        id: string;
        title: string;
        page_number: number;
        text: string;
        image: string; // base64
        image_url: string; // Added by proxy
        full_image_url: string; // Added by proxy
      };
    }>;
  };
}

export interface ChatMessage {
  role: 'user' | 'assistant' | 'system';
  content: string;
}

class ColPaliClient {
  private async fetchWithTimeout(url: string, options: RequestInit, timeout = 30000) {
    const controller = new AbortController();
    const id = setTimeout(() => controller.abort(), timeout);
    
    try {
      const response = await fetch(url, {
        ...options,
        signal: controller.signal,
      });
      return response;
    } finally {
      clearTimeout(id);
    }
  }

  async search(query: string, limit = 10): Promise<SearchResult> {
    const response = await this.fetchWithTimeout(`${API_URL}/search`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ query, limit }),
    });

    if (!response.ok) {
      throw new Error(`Search failed: ${response.statusText}`);
    }

    return response.json();
  }

  async* chat(messages: ChatMessage[], context: string[] = []) {
    const response = await fetch(`${API_URL}/chat`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ messages, context }),
    });

    if (!response.ok) {
      throw new Error(`Chat failed: ${response.statusText}`);
    }

    const reader = response.body?.getReader();
    if (!reader) throw new Error('No response body');

    const decoder = new TextDecoder();
    let buffer = '';

    while (true) {
      const { done, value } = await reader.read();
      if (done) break;

      buffer += decoder.decode(value, { stream: true });
      const lines = buffer.split('\\n');
      buffer = lines.pop() || '';

      for (const line of lines) {
        if (line.startsWith('data: ')) {
          const data = line.slice(6);
          if (data === '[DONE]') return;
          
          try {
            const parsed = JSON.parse(data);
            yield parsed;
          } catch (e) {
            console.error('Failed to parse SSE data:', e);
          }
        }
      }
    }
  }

  async getSimilarityMap(docId: string, query: string) {
    const response = await this.fetchWithTimeout(`${API_URL}/search/similarity-map`, {
      method: 'POST',
      headers: { 'Content-Type': 'application/json' },
      body: JSON.stringify({ docId, query }),
    });

    if (!response.ok) {
      throw new Error(`Similarity map failed: ${response.statusText}`);
    }

    return response.json();
  }

  getImageUrl(docId: string, type: 'thumbnail' | 'full' = 'thumbnail'): string {
    return `${API_URL}/search/image/${docId}/${type}`;
  }

  async checkHealth() {
    const response = await this.fetchWithTimeout(`${API_URL.replace('/api', '')}/health`, {
      method: 'GET',
    }, 5000);

    return response.json();
  }
}

// Export singleton instance
export const colpaliClient = new ColPaliClient();

// Usage examples:
/*
// In your Next.js component or API route:

// Search
const results = await colpaliClient.search('annual report 2023', 20);

// Display images directly from proxy URLs
results.root.children.forEach(hit => {
  const imageUrl = hit.fields.image_url; // Proxy URL for thumbnail
  const fullImageUrl = hit.fields.full_image_url; // Proxy URL for full image
});

// Chat with streaming
const messages = [{ role: 'user', content: 'What is the revenue?' }];
for await (const chunk of colpaliClient.chat(messages)) {
  console.log(chunk);
}

// Get image URL for direct use in <img> tags
const imageUrl = colpaliClient.getImageUrl('doc123', 'thumbnail');

// Check system health
const health = await colpaliClient.checkHealth();
*/