/**
 * OpenAI-compatible AI client for multiple providers.
 * Supports OpenAI, Ollama, OpenRouter, and any OpenAI-compatible API.
 */

export interface AIConfig {
  apiKey: string;
  baseUrl: string;
  model: string;
  systemPrompt: string;
  groupPrompt?: string;
}

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

/**
 * Mask an API key for safe display
 * sk-proj-abc123xyz... → sk-***...***xyz
 */
export function maskApiKey(key: string): string {
  if (!key || key.length < 8) return '***';
  const start = key.substring(0, 3);
  const end = key.substring(key.length - 3);
  return `${start}***...***${end}`;
}

/**
 * Generate AI response using OpenAI-compatible API
 */
export async function generateAIResponse(
  config: AIConfig,
  context: AIMessage[],
  userMessage: string
): Promise<string> {
  const messages: AIMessage[] = [];

  // Build system prompt (global + group)
  let systemPrompt = config.systemPrompt;
  if (config.groupPrompt) {
    systemPrompt += '\n\n' + config.groupPrompt;
  }
  messages.push({ role: 'system', content: systemPrompt });

  // Add context messages (last 50)
  messages.push(...context.slice(-50));

  // Add user message
  messages.push({ role: 'user', content: userMessage });

  const response = await fetch(`${config.baseUrl}/chat/completions`, {
    method: 'POST',
    headers: {
      'Content-Type': 'application/json',
      'Authorization': `Bearer ${config.apiKey}`,
    },
    body: JSON.stringify({
      model: config.model,
      messages,
      max_tokens: 500,
      temperature: 0.8,
      presence_penalty: 0.6,
      frequency_penalty: 0.6,
    }),
  });

  if (!response.ok) {
    const error = await response.text();
    throw new Error(`AI API error: ${response.status} - ${error}`);
  }

  const data = await response.json() as { choices: Array<{ message?: { content?: string } }> };
  return data.choices[0]?.message?.content || 'Keine Antwort erhalten.';
}

/**
 * Get default base URL for a provider
 */
export function getDefaultBaseUrl(provider: string): string {
  switch (provider) {
    case 'openai':
      return 'https://api.openai.com/v1';
    case 'ollama':
      return 'http://localhost:11434/v1';
    case 'openrouter':
      return 'https://openrouter.ai/api/v1';
    default:
      return 'https://api.openai.com/v1';
  }
}

/**
 * Get available models for a provider
 */
export function getProviderModels(provider: string): string[] {
  switch (provider) {
    case 'openai':
      return ['gpt-4o-mini', 'gpt-4o', 'gpt-3.5-turbo'];
    case 'ollama':
      return ['llama3', 'llama3.1', 'mistral', 'codellama'];
    case 'openrouter':
      return ['openai/gpt-4o-mini', 'anthropic/claude-3.5-sonnet', 'meta-llama/llama-3.1-8b-instruct'];
    default:
      return ['gpt-4o-mini'];
  }
}