lib/openrouter.ts

// OpenRouter Model Interfaces
export interface OpenRouterModelArchitecture {
  input_modalities: string[];
  output_modalities: string[];
  tokenizer: string;
  instruct_type: string | null;
}

export interface OpenRouterModelPricing {
  prompt: string;
  completion: string;
  request: string;
  image: string;
  web_search: string;
  internal_reasoning: string;
  input_cache_read: string;
  input_cache_write: string;
}

export interface OpenRouterModelTopProvider {
  context_length: number;
  max_completion_tokens: number;
  is_moderated: boolean;
}

export interface OpenRouterModel {
  id: string;
  canonical_slug: string;
  name: string;
  created: number;
  description: string;
  context_length: number;
  architecture: OpenRouterModelArchitecture;
  pricing: OpenRouterModelPricing;
  top_provider: OpenRouterModelTopProvider;
  per_request_limits: Record<string, unknown>;
  supported_parameters: string[];
}

export interface OpenRouterModelsResponse {
  data: OpenRouterModel[];
}

// Existing interfaces
export interface OpenRouterMessage {
  role: "system" | "user" | "assistant";
  content: string;
}

export interface OpenRouterRequest {
  model: string;
  messages: OpenRouterMessage[];
  max_tokens?: number;
  temperature?: number;
  stream?: boolean;
}

// Cache for model information to avoid repeated API calls
const modelCache = new Map<string, OpenRouterModel>();

// Fetch available models from OpenRouter
export async function fetchOpenRouterModels(
  apiKey?: string
): Promise<OpenRouterModel[]> {
  console.log('🔄 fetchOpenRouterModels called, API key provided:', !!apiKey);
  
  const headers: Record<string, string> = {
    "Content-Type": "application/json",
    "HTTP-Referer": process.env.NEXT_PUBLIC_SITE_URL || "http://localhost:3000",
    "X-Title": "DeepSite - AI Website Builder",
  };

  // Add authorization header if API key is provided (for potentially better results)
  if (apiKey) {
    headers["Authorization"] = `Bearer ${apiKey}`;
  }

  console.log('📡 Making request to OpenRouter API...');
  console.log('🔗 Headers:', Object.keys(headers));

  const response = await fetch("https://openrouter.ai/api/v1/models", {
    method: "GET",
    headers,
  });

  console.log('📥 OpenRouter API response status:', response.status);

  if (!response.ok) {
    const errorText = await response.text();
    console.error('❌ OpenRouter API error:', response.status, errorText);
    throw new Error(`Failed to fetch OpenRouter models: ${response.statusText}`);
  }

  const data: OpenRouterModelsResponse = await response.json();
  console.log('✅ OpenRouter API returned', data.data.length, 'models');
  
  return data.data;
}

export async function callOpenRouter(
  request: OpenRouterRequest,
  apiKey: string,
  signal?: AbortSignal
): Promise<Response> {
  console.log('🔑 CallOpenRouter called with:', {
    model: request.model,
    apiKeyProvided: !!apiKey,
    apiKeyPrefix: apiKey ? apiKey.substring(0, 10) + '...' : 'none'
  });

  const response = await fetch("https://openrouter.ai/api/v1/chat/completions", {
    method: "POST",
    headers: {
      "Authorization": `Bearer ${apiKey}`,
      "Content-Type": "application/json",
      "HTTP-Referer": process.env.NEXT_PUBLIC_SITE_URL || "http://localhost:3000",
      "X-Title": "DeepSite - AI Website Builder",
    },
    body: JSON.stringify({
      ...request,
      stream: true, // Always use streaming for consistency
    }),
    signal,
  });

  console.log('📥 OpenRouter chat response status:', response.status);

  if (!response.ok) {
    const errorData = await response.json().catch(() => ({}));
    console.error('❌ OpenRouter error details:', {
      status: response.status,
      statusText: response.statusText,
      errorData
    });
    
    // Handle specific OpenRouter error cases
    if (response.status === 401) {
      throw new Error("Invalid OpenRouter API key. Please check your API key and try again.");
    } else if (response.status === 429) {
      throw new Error("OpenRouter rate limit exceeded. Please try again later.");
    } else if (response.status === 402) {
      throw new Error("Insufficient credits in your OpenRouter account. Please add credits and try again.");
    } else if (response.status === 400) {
      throw new Error(errorData.error?.message || "Invalid request to OpenRouter API. Please check your model selection.");
    }
    
    throw new Error(
      errorData.error?.message || 
      `OpenRouter API error: ${response.status} ${response.statusText}`
    );
  }

  console.log('✅ OpenRouter chat request successful');
  return response;
}

export async function* parseOpenRouterStream(response: Response) {
  const reader = response.body?.getReader();
  if (!reader) {
    throw new Error("No readable stream in OpenRouter response");
  }

  const decoder = new TextDecoder();
  let buffer = "";
  let chunkCount = 0;
  let contentCount = 0;

  console.log('🔄 Starting OpenRouter stream parsing...');

  try {
    while (true) {
      const { done, value } = await reader.read();
      if (done) {
        console.log('✅ OpenRouter stream parsing completed:', {
          totalChunks: chunkCount,
          totalContentChunks: contentCount,
          bufferRemaining: buffer.length
        });
        break;
      }

      chunkCount++;
      // Append new chunk to buffer
      buffer += decoder.decode(value, { stream: true });

      // Process complete lines from buffer
      while (true) {
        const lineEnd = buffer.indexOf('\n');
        if (lineEnd === -1) break;

        const line = buffer.slice(0, lineEnd).trim();
        buffer = buffer.slice(lineEnd + 1);

        // Skip empty lines
        if (!line) continue;

        // Handle SSE comments (ignore them as per OpenRouter docs)
        if (line.startsWith(':')) {
          console.log('💬 SSE comment:', line);
          continue;
        }

        if (line.startsWith('data: ')) {
          const data = line.slice(6);
          if (data === '[DONE]') {
            console.log('🏁 Received [DONE] signal from OpenRouter');
            return;
          }

          try {
            const parsed = JSON.parse(data);
            const content = parsed.choices?.[0]?.delta?.content;
            if (content) {
              contentCount++;
              console.log(`📝 Content chunk ${contentCount}:`, {
                length: content.length,
                preview: content.substring(0, 50) + (content.length > 50 ? '...' : '')
              });
              yield content;
            }
          } catch (parseError) {
            console.warn('⚠️ Failed to parse OpenRouter SSE data:', {
              data: data.substring(0, 100),
              error: parseError
            });
            // Continue processing other lines instead of breaking
          }
        }
      }
    }
  } catch (streamError) {
    console.error('❌ Error in OpenRouter stream parsing:', streamError);
    throw streamError;
  } finally {
    reader.releaseLock();
  }
}

// Get model information from OpenRouter API with caching
export async function getOpenRouterModelInfo(
  modelId: string, 
  apiKey?: string
): Promise<OpenRouterModel | null> {
  // Check cache first
  if (modelCache.has(modelId)) {
    console.log('📋 Using cached model info for:', modelId);
    return modelCache.get(modelId) || null;
  }

  try {
    console.log('🔍 Fetching model info for:', modelId);
    const models = await fetchOpenRouterModels(apiKey);
    
    // Cache all models for future use
    models.forEach(model => {
      modelCache.set(model.id, model);
    });

    const modelInfo = models.find(model => model.id === modelId);
    if (!modelInfo) {
      console.warn('⚠️ Model not found in OpenRouter API:', modelId);
      return null;
    }

    console.log('✅ Found model info:', {
      id: modelInfo.id,
      contextLength: modelInfo.context_length,
      maxCompletionTokens: modelInfo.top_provider.max_completion_tokens
    });

    return modelInfo;
  } catch (error) {
    console.error('❌ Failed to fetch model info:', error);
    return null;
  }
}

// Calculate safe max_tokens based on model context length and estimated input tokens
export function calculateSafeMaxTokens(
  contextLength: number,
  estimatedInputTokens: number,
  maxCompletionTokens?: number
): number {
  // Leave some buffer for safety (10% of context length or minimum 1000 tokens)
  const safetyBuffer = Math.max(Math.floor(contextLength * 0.1), 1000);
  
  // Calculate available tokens for output
  const availableTokens = contextLength - estimatedInputTokens - safetyBuffer;
  
  // Respect model's max completion tokens if available
  const modelMaxTokens = maxCompletionTokens || availableTokens;
  
  // Use the smaller of available tokens or model's max completion tokens
  const safeMaxTokens = Math.min(availableTokens, modelMaxTokens);
  
  // Ensure we don't go below a reasonable minimum
  const finalMaxTokens = Math.max(safeMaxTokens, 1000);
  
  console.log('🧮 Token calculation:', {
    contextLength,
    estimatedInputTokens,
    safetyBuffer,
    availableTokens,
    modelMaxTokens,
    finalMaxTokens
  });
  
  return finalMaxTokens;
}

// Rough token estimation (1 token ≈ 4 characters for most models)
export function estimateTokenCount(text: string): number {
  // More sophisticated estimation could use tiktoken library, but this is a reasonable approximation
  return Math.ceil(text.length / 4);
}