import React, { createContext, useContext, useState, useEffect } from 'react';
import { WEBLLM_MODELS, isWebLLMSupported } from '../utils/webLLMUtils';

// Define types for provider
export type Provider = 'openai' | 'anthropic' | 'google' | 'deepseek' | 'webllm' | 'custom';

// Model interface
export interface Model {
  id: string;
  name: string;
  maxTokens?: number;
  provider: Provider;
}

// Configuration context interface
interface ConfigContextType {
  provider: Provider;
  setProvider: (provider: Provider) => void;
  apiKey: string;
  setApiKey: (key: string) => void;
  endpoint: string;
  setEndpoint: (endpoint: string) => void;
  selectedModel: string;
  setSelectedModel: (model: string) => void;
  availableModels: Model[];
  streamingEnabled: boolean;
  setStreamingEnabled: (enabled: boolean) => void;
  isWebLLMAvailable: boolean;
  webLLMStatusMessage: string;
}

// Create the context
const ConfigContext = createContext<ConfigContextType | undefined>(undefined);

// Default OpenAI models
const OPENAI_MODELS: Model[] = [
  { id: 'gpt-4o', name: 'GPT-4o', provider: 'openai' },
  { id: 'gpt-4-turbo', name: 'GPT-4 Turbo', provider: 'openai' },
  { id: 'gpt-4', name: 'GPT-4', provider: 'openai' },
  { id: 'gpt-3.5-turbo', name: 'GPT-3.5 Turbo', provider: 'openai' }
];

// Default Anthropic models
const ANTHROPIC_MODELS: Model[] = [
  { id: 'claude-3-opus-20240229', name: 'Claude 3 Opus', provider: 'anthropic' },
  { id: 'claude-3-sonnet-20240229', name: 'Claude 3 Sonnet', provider: 'anthropic' },
  { id: 'claude-3-haiku-20240307', name: 'Claude 3 Haiku', provider: 'anthropic' },
  { id: 'claude-2.1', name: 'Claude 2.1', provider: 'anthropic' },
  { id: 'claude-2.0', name: 'Claude 2.0', provider: 'anthropic' },
  { id: 'claude-instant-1.2', name: 'Claude Instant 1.2', provider: 'anthropic' }
];

// Default Google models
const GOOGLE_MODELS: Model[] = [
  { id: 'gemini-1.5-pro', name: 'Gemini 1.5 Pro', provider: 'google' },
  { id: 'gemini-1.5-flash', name: 'Gemini 1.5 Flash', provider: 'google' },
  { id: 'gemini-1.0-pro', name: 'Gemini 1.0 Pro', provider: 'google' },
  { id: 'gemini-1.0-ultra', name: 'Gemini 1.0 Ultra', provider: 'google' }
];

// Default DeepSeek models
const DEEPSEEK_MODELS: Model[] = [
  { id: 'deepseek-chat', name: 'DeepSeek Chat', provider: 'deepseek' },
  { id: 'deepseek-coder', name: 'DeepSeek Coder', provider: 'deepseek' }
];

// WebLLM models (from WebLLMUtils)
const webLLMModels: Model[] = WEBLLM_MODELS.map(model => ({
  id: model.id,
  name: model.name,
  maxTokens: model.contextLength,
  provider: 'webllm' as Provider
}));

// Get provider endpoint
const getProviderEndpoint = (provider: Provider): string => {
  switch (provider) {
    case 'openai':
      return 'https://api.openai.com/v1/chat/completions';
    case 'anthropic':
      return 'https://api.anthropic.com/v1/messages';
    case 'google':
      return 'https://generativelanguage.googleapis.com/v1beta/models/gemini-1.0-pro:generateContent';
    case 'deepseek':
      return 'https://api.deepseek.com/v1/chat/completions';
    case 'webllm':
      return 'browser'; // Special marker for browser-based models
    case 'custom':
      return '';
    default:
      return '';
  }
};

// Get models for provider
const getModelsForProvider = (provider: Provider): Model[] => {
  switch (provider) {
    case 'openai':
      return OPENAI_MODELS;
    case 'anthropic':
      return ANTHROPIC_MODELS;
    case 'google':
      return GOOGLE_MODELS;
    case 'deepseek':
      return DEEPSEEK_MODELS;
    case 'webllm':
      return webLLMModels;
    case 'custom':
      return []; // Custom provider requires user to specify models
    default:
      return [];
  }
};

export const ConfigProvider: React.FC<{ children: React.ReactNode }> = ({ children }) => {
  // Initialize from localStorage if available
  const [provider, setProvider] = useState<Provider>(() => {
    if (typeof window !== 'undefined') {
      const savedProvider = localStorage.getItem('provider');
      return (savedProvider as Provider) || 'openai';
    }
    return 'openai';
  });

  const [apiKey, setApiKey] = useState<string>(() => {
    if (typeof window !== 'undefined') {
      return localStorage.getItem('apiKey') || '';
    }
    return '';
  });

  const [endpoint, setEndpoint] = useState<string>(() => {
    if (typeof window !== 'undefined') {
      const savedEndpoint = localStorage.getItem('endpoint');
      if (savedEndpoint) return savedEndpoint;
    }
    return getProviderEndpoint(provider);
  });

  const [selectedModel, setSelectedModel] = useState<string>(() => {
    if (typeof window !== 'undefined') {
      const savedModel = localStorage.getItem('selectedModel');
      if (savedModel) return savedModel;
    }

    // Default models for each provider
    const defaultModels: Record<Provider, string> = {
      'openai': 'gpt-3.5-turbo',
      'anthropic': 'claude-3-haiku-20240307',
      'google': 'gemini-1.0-pro',
      'deepseek': 'deepseek-chat',
      'webllm': 'TinyLlama-1.1B-Chat-v1.0-q4f16_1',
      'custom': ''
    };

    return defaultModels[provider];
  });

  const [streamingEnabled, setStreamingEnabled] = useState<boolean>(() => {
    if (typeof window !== 'undefined') {
      const saved = localStorage.getItem('streamingEnabled');
      return saved ? saved === 'true' : true; // default to true
    }
    return true;
  });

  // WebLLM support
  const [isWebLLMAvailable, setIsWebLLMAvailable] = useState<boolean>(false);
  const [webLLMStatusMessage, setWebLLMStatusMessage] = useState<string>('Checking WebLLM support...');

  // Update available models when provider changes
  const [availableModels, setAvailableModels] = useState<Model[]>(
    getModelsForProvider(provider)
  );

  // Check WebLLM support on component mount
  useEffect(() => {
    // Only run in browser environment
    if (typeof window !== 'undefined') {
      try {
        const supported = isWebLLMSupported();
        setIsWebLLMAvailable(supported);
        setWebLLMStatusMessage(supported
          ? 'WebLLM is supported in this browser'
          : 'WebLLM is not supported in this browser (requires WebAssembly, SharedArrayBuffer, and Atomics API)');
      } catch (error) {
        setIsWebLLMAvailable(false);
        setWebLLMStatusMessage('Error checking WebLLM support: ' +
          (error instanceof Error ? error.message : 'Unknown error'));
      }
    }
  }, []);

  // Update models when provider changes
  useEffect(() => {
    const models = getModelsForProvider(provider);
    setAvailableModels(models);

    // If the selected model is not in the new provider's models, select the first one
    const modelExists = models.some(model => model.id === selectedModel);
    if (!modelExists && models.length > 0) {
      setSelectedModel(models[0].id);
    }

    // Update endpoint when provider changes (unless custom)
    if (provider !== 'custom') {
      setEndpoint(getProviderEndpoint(provider));
    }

    // Save to localStorage
    if (typeof window !== 'undefined') {
      localStorage.setItem('provider', provider);
    }
  }, [provider, selectedModel]);

  // Save settings to localStorage when they change
  useEffect(() => {
    if (typeof window !== 'undefined') {
      localStorage.setItem('apiKey', apiKey);
      localStorage.setItem('endpoint', endpoint);
      localStorage.setItem('selectedModel', selectedModel);
      localStorage.setItem('streamingEnabled', String(streamingEnabled));
    }
  }, [apiKey, endpoint, selectedModel, streamingEnabled]);

  const value = {
    provider,
    setProvider,
    apiKey,
    setApiKey,
    endpoint,
    setEndpoint,
    selectedModel,
    setSelectedModel,
    availableModels,
    streamingEnabled,
    setStreamingEnabled,
    isWebLLMAvailable,
    webLLMStatusMessage
  };

  return (
    <ConfigContext.Provider value={value}>
      {children}
    </ConfigContext.Provider>
  );
};

export const useConfig = () => {
  const context = useContext(ConfigContext);
  if (context === undefined) {
    throw new Error('useConfig must be used within a ConfigProvider');
  }
  return context;
};