/**
 * LiteLLM Executor - Execute LiteLLM endpoints with context caching
 * Integrates with context-cache for file packing and LiteLLM client for API calls
 */

import { getLiteLLMClient } from './litellm-client.js';
import { handler as contextCacheHandler } from './context-cache.js';
import {
  findEndpointById,
  getProviderWithResolvedEnvVars,
} from '../config/litellm-api-config-manager.js';
import type { CustomEndpoint, ProviderCredential } from '../types/litellm-api-config.js';

export interface LiteLLMExecutionOptions {
  prompt: string;
  endpointId: string; // Custom endpoint ID (e.g., "my-gpt4o")
  baseDir: string; // Project base directory
  cwd?: string; // Working directory for file resolution
  includeDirs?: string[]; // Additional directories for @patterns
  enableCache?: boolean; // Override endpoint cache setting
  onOutput?: (data: { type: string; data: string }) => void;
}

export interface LiteLLMExecutionResult {
  success: boolean;
  output: string;
  model: string;
  provider: string;
  cacheUsed: boolean;
  cachedFiles?: string[];
  error?: string;
}

/**
 * Extract @patterns from prompt text
 */
export function extractPatterns(prompt: string): string[] {
  // Match @path patterns: @src/**/*.ts, @CLAUDE.md, @../shared/**/*
  const regex = /@([^\s]+)/g;
  const patterns: string[] = [];
  let match;
  while ((match = regex.exec(prompt)) !== null) {
    patterns.push('@' + match[1]);
  }
  return patterns;
}

/**
 * Execute LiteLLM endpoint with optional context caching
 */
export async function executeLiteLLMEndpoint(
  options: LiteLLMExecutionOptions
): Promise<LiteLLMExecutionResult> {
  const { prompt, endpointId, baseDir, cwd, includeDirs, enableCache, onOutput } = options;

  // 1. Find endpoint configuration
  const endpoint = findEndpointById(baseDir, endpointId);
  if (!endpoint) {
    return {
      success: false,
      output: '',
      model: '',
      provider: '',
      cacheUsed: false,
      error: `Endpoint not found: ${endpointId}`,
    };
  }

  // 2. Get provider with resolved env vars
  const provider = getProviderWithResolvedEnvVars(baseDir, endpoint.providerId);
  if (!provider) {
    return {
      success: false,
      output: '',
      model: '',
      provider: '',
      cacheUsed: false,
      error: `Provider not found: ${endpoint.providerId}`,
    };
  }

  // Verify API key is available
  if (!provider.resolvedApiKey) {
    return {
      success: false,
      output: '',
      model: endpoint.model,
      provider: provider.type,
      cacheUsed: false,
      error: `API key not configured for provider: ${provider.name}`,
    };
  }

  // 3. Process context cache if enabled
  let finalPrompt = prompt;
  let cacheUsed = false;
  let cachedFiles: string[] = [];

  const shouldCache = enableCache ?? endpoint.cacheStrategy.enabled;
  if (shouldCache) {
    const patterns = extractPatterns(prompt);
    if (patterns.length > 0) {
      if (onOutput) {
        onOutput({ type: 'stderr', data: `[Context cache: Found ${patterns.length} @patterns]\n` });
      }

      // Pack files into cache
      const packResult = await contextCacheHandler({
        operation: 'pack',
        patterns,
        cwd: cwd || process.cwd(),
        include_dirs: includeDirs,
        ttl: endpoint.cacheStrategy.ttlMinutes * 60 * 1000,
        max_file_size: endpoint.cacheStrategy.maxSizeKB * 1024,
      });

      if (packResult.success && packResult.result) {
        const pack = packResult.result as any;

        if (onOutput) {
          onOutput({
            type: 'stderr',
            data: `[Context cache: Packed ${pack.files_packed} files, ${pack.total_bytes} bytes]\n`,
          });
        }

        // Read cached content
        const readResult = await contextCacheHandler({
          operation: 'read',
          session_id: pack.session_id,
          limit: endpoint.cacheStrategy.maxSizeKB * 1024,
        });

        if (readResult.success && readResult.result) {
          const read = readResult.result as any;
          // Prepend cached content to prompt
          finalPrompt = `${read.content}\n\n---\n\n${prompt}`;
          cacheUsed = true;
          cachedFiles = pack.files_packed ? Array(pack.files_packed).fill('...') : [];

          if (onOutput) {
            onOutput({ type: 'stderr', data: `[Context cache: Applied to prompt]\n` });
          }
        }
      } else if (packResult.error) {
        if (onOutput) {
          onOutput({ type: 'stderr', data: `[Context cache warning: ${packResult.error}]\n` });
        }
      }
    }
  }

  // 4. Call LiteLLM
  try {
    if (onOutput) {
      onOutput({
        type: 'stderr',
        data: `[LiteLLM: Calling ${provider.type}/${endpoint.model}]\n`,
      });
    }

    const client = getLiteLLMClient({
      pythonPath: 'python',
      timeout: 120000, // 2 minutes
    });

    // Configure provider credentials via environment
    // LiteLLM uses standard env vars like OPENAI_API_KEY, ANTHROPIC_API_KEY
    const envVarName = getProviderEnvVarName(provider.type);
    if (envVarName) {
      process.env[envVarName] = provider.resolvedApiKey;
    }

    // Set base URL if custom
    if (provider.apiBase) {
      const baseUrlEnvVar = getProviderBaseUrlEnvVarName(provider.type);
      if (baseUrlEnvVar) {
        process.env[baseUrlEnvVar] = provider.apiBase;
      }
    }

    // Use litellm-client to call chat
    const response = await client.chat(finalPrompt, endpoint.model);

    if (onOutput) {
      onOutput({ type: 'stdout', data: response });
    }

    return {
      success: true,
      output: response,
      model: endpoint.model,
      provider: provider.type,
      cacheUsed,
      cachedFiles,
    };
  } catch (error) {
    const errorMsg = (error as Error).message;
    if (onOutput) {
      onOutput({ type: 'stderr', data: `[LiteLLM error: ${errorMsg}]\n` });
    }

    return {
      success: false,
      output: '',
      model: endpoint.model,
      provider: provider.type,
      cacheUsed,
      error: errorMsg,
    };
  }
}

/**
 * Get environment variable name for provider API key
 */
function getProviderEnvVarName(providerType: string): string | null {
  const envVarMap: Record<string, string> = {
    openai: 'OPENAI_API_KEY',
    anthropic: 'ANTHROPIC_API_KEY',
    google: 'GOOGLE_API_KEY',
    azure: 'AZURE_API_KEY',
    mistral: 'MISTRAL_API_KEY',
    deepseek: 'DEEPSEEK_API_KEY',
  };

  return envVarMap[providerType] || null;
}

/**
 * Get environment variable name for provider base URL
 */
function getProviderBaseUrlEnvVarName(providerType: string): string | null {
  const envVarMap: Record<string, string> = {
    openai: 'OPENAI_API_BASE',
    anthropic: 'ANTHROPIC_API_BASE',
    azure: 'AZURE_API_BASE',
  };

  return envVarMap[providerType] || null;
}