import { useEffect, useState } from 'react';
import { getStoredGatewayToken, getStoredGatewayUrl } from '../../lib/gateway-client';
import { useGatewayStore } from '../../store/gatewayStore';
import { useChatStore } from '../../store/chatStore';
import { silentErrorHandler } from '../../lib/error-utils';

// Helper function to format context window size
function formatContextWindow(tokens?: number): string {
  if (!tokens) return '';
  if (tokens >= 1000000) {
    return `${(tokens / 1000000).toFixed(1)}M`;
  }
  if (tokens >= 1000) {
    return `${(tokens / 1000).toFixed(0)}K`;
  }
  return `${tokens}`;
}

export function ModelsAPI() {
  const { connectionState, connect, disconnect, quickConfig, saveQuickConfig, models, modelsLoading, modelsError, loadModels } = useGatewayStore();
  const { currentModel, setCurrentModel } = useChatStore();
  const [gatewayUrl, setGatewayUrl] = useState(getStoredGatewayUrl());
  const [gatewayToken, setGatewayToken] = useState(quickConfig.gatewayToken || getStoredGatewayToken());

  const connected = connectionState === 'connected';
  const connecting = connectionState === 'connecting' || connectionState === 'reconnecting';

  // Load models when connected
  useEffect(() => {
    if (connected && models.length === 0 && !modelsLoading) {
      loadModels();
    }
  }, [connected, models.length, modelsLoading, loadModels]);

  useEffect(() => {
    setGatewayUrl(quickConfig.gatewayUrl || getStoredGatewayUrl());
    setGatewayToken(quickConfig.gatewayToken || getStoredGatewayToken());
  }, [quickConfig.gatewayToken, quickConfig.gatewayUrl]);

  const handleReconnect = () => {
    disconnect();
    setTimeout(() => connect(
      gatewayUrl || quickConfig.gatewayUrl || 'ws://127.0.0.1:50051/ws',
      gatewayToken || quickConfig.gatewayToken || getStoredGatewayToken()
    ).catch(silentErrorHandler('ModelsAPI')), 500);
  };

  const handleSaveGatewaySettings = () => {
    saveQuickConfig({
      gatewayUrl,
      gatewayToken,
    }).catch(silentErrorHandler('ModelsAPI'));
  };

  const handleRefreshModels = () => {
    loadModels();
  };

  return (
    <div className="max-w-3xl">
      <div className="flex justify-between items-center mb-6">
        <h1 className="text-xl font-bold text-gray-900">模型与 API</h1>
        <button
          onClick={handleReconnect}
          disabled={connecting}
          className="text-xs text-gray-500 hover:text-gray-700 px-3 py-1.5 border border-gray-200 rounded-lg transition-colors disabled:opacity-50"
        >
          {connecting ? '连接中...' : '重新连接'}
        </button>
      </div>

      <div className="mb-6">
        <h3 className="text-xs font-semibold text-gray-500 mb-3 uppercase tracking-wider">当前会话模型</h3>
        <div className="bg-white border border-gray-200 rounded-xl p-4 shadow-sm space-y-2">
          <div className="flex items-center justify-between">
            <span className="text-sm text-gray-500">当前选择</span>
            <span className="text-sm font-medium text-orange-600">{currentModel}</span>
          </div>
          <div className="flex items-center justify-between">
            <span className="text-sm text-gray-500">Gateway 状态</span>
            <span className={`text-sm ${connected ? 'text-green-600' : connecting ? 'text-yellow-600' : 'text-gray-400'}`}>
              {connected ? '已连接' : connecting ? '连接中...' : '未连接'}
            </span>
          </div>
        </div>
      </div>

      <div className="mb-6">
        <div className="flex justify-between items-center mb-3">
          <h3 className="text-xs font-semibold text-gray-500 uppercase tracking-wider">可选模型</h3>
          <div className="flex items-center gap-2">
            <span className="text-xs text-gray-400">切换后用于新的桌面对话请求</span>
            {connected && (
              <button
                onClick={handleRefreshModels}
                disabled={modelsLoading}
                className="text-xs text-orange-600 hover:text-orange-700 disabled:opacity-50"
              >
                {modelsLoading ? '加载中...' : '刷新'}
              </button>
            )}
          </div>
        </div>

        {/* Loading state */}
        {modelsLoading && (
          <div className="bg-white rounded-xl border border-gray-200 p-8 shadow-sm">
            <div className="flex items-center justify-center">
              <div className="animate-spin rounded-full h-6 w-6 border-b-2 border-orange-500"></div>
              <span className="ml-3 text-sm text-gray-500">正在加载模型列表...</span>
            </div>
          </div>
        )}

        {/* Error state */}
        {modelsError && !modelsLoading && (
          <div className="bg-white rounded-xl border border-red-200 p-4 shadow-sm">
            <div className="flex items-start gap-3">
              <svg className="w-5 h-5 text-red-500 flex-shrink-0 mt-0.5" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M12 8v4m0 4h.01M21 12a9 9 0 11-18 0 9 9 0 0118 0z" />
              </svg>
              <div>
                <p className="text-sm font-medium text-red-800">加载模型列表失败</p>
                <p className="text-xs text-red-600 mt-1">{modelsError}</p>
                <button
                  onClick={handleRefreshModels}
                  className="mt-2 text-xs text-red-600 hover:text-red-700 underline"
                >
                  重试
                </button>
              </div>
            </div>
          </div>
        )}

        {/* Not connected state */}
        {!connected && !modelsLoading && !modelsError && (
          <div className="bg-white rounded-xl border border-gray-200 p-6 shadow-sm">
            <div className="text-center">
              <svg className="w-8 h-8 text-gray-300 mx-auto mb-3" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M13 10V3L4 14h7v7l9-11h-7z" />
              </svg>
              <p className="text-sm text-gray-500">请先连接 Gateway 以获取可用模型列表</p>
            </div>
          </div>
        )}

        {/* Model list */}
        {connected && !modelsLoading && !modelsError && models.length > 0 && (
          <div className="bg-white rounded-xl border border-gray-200 divide-y divide-gray-100 shadow-sm">
            {models.map((model) => {
              const isActive = model.id === currentModel;
              return (
                <div key={model.id} className={`flex justify-between items-center p-4 ${isActive ? 'bg-orange-50/50' : ''}`}>
                  <div>
                    <div className="text-sm text-gray-900">{model.name}</div>
                    <div className="flex items-center gap-2 mt-1">
                      {model.provider && (
                        <span className="text-xs text-gray-400">{model.provider}</span>
                      )}
                      {model.contextWindow && (
                        <span className="text-xs text-gray-400">
                          {model.provider && '|'}
                          上下文 {formatContextWindow(model.contextWindow)}
                        </span>
                      )}
                      {model.maxOutput && (
                        <span className="text-xs text-gray-400">
                          最大输出 {formatContextWindow(model.maxOutput)}
                        </span>
                      )}
                    </div>
                  </div>
                  <div className="flex gap-2 text-xs items-center">
                    {isActive ? (
                      <span className="px-2 py-1 bg-green-100 text-green-700 rounded text-xs">当前选择</span>
                    ) : (
                      <button onClick={() => setCurrentModel(model.id)} className="text-orange-600 hover:underline">切换到此模型</button>
                    )}
                  </div>
                </div>
              );
            })}
          </div>
        )}

        {/* Empty state */}
        {connected && !modelsLoading && !modelsError && models.length === 0 && (
          <div className="bg-white rounded-xl border border-gray-200 p-6 shadow-sm">
            <div className="text-center">
              <svg className="w-8 h-8 text-gray-300 mx-auto mb-3" fill="none" stroke="currentColor" viewBox="0 0 24 24">
                <path strokeLinecap="round" strokeLinejoin="round" strokeWidth={2} d="M9.172 16.172a4 4 0 015.656 0M9 10h.01M15 10h.01M12 20a8 8 0 100-16 8 8 0 000 16z" />
              </svg>
              <p className="text-sm text-gray-500">暂无可用模型</p>
              <p className="text-xs text-gray-400 mt-1">请检查 Gateway 配置或 Provider 设置</p>
            </div>
          </div>
        )}

        <div className="mt-3 text-xs text-amber-700 bg-amber-50 rounded-lg p-3">
          当前页面只支持切换桌面端可选模型与维护 Gateway 连接信息，Provider Key、自定义模型增删改尚未在此页面接入。
        </div>
      </div>

      <div className="flex items-center justify-between mb-4">
        <div className="flex items-center gap-2">
          <span className="text-sm font-medium text-gray-900">Gateway URL</span>
          <span className={`px-2 py-0.5 rounded text-xs border ${connected ? 'bg-green-50 text-green-600 border-green-100' : 'bg-red-50 text-red-600 border-red-100'}`}>
            {connected ? '已连接' : connecting ? '连接中...' : '未连接'}
          </span>
        </div>
        <div className="flex gap-2">
          <button onClick={handleReconnect} className="text-xs text-gray-500 hover:text-gray-700 px-3 py-1.5 border border-gray-200 rounded-lg transition-colors">
            重新连接
          </button>
          <button onClick={handleSaveGatewaySettings} className="text-xs text-white bg-orange-500 hover:bg-orange-600 px-3 py-1.5 rounded-lg transition-colors">
            保存连接设置
          </button>
        </div>
      </div>
      <div className="space-y-3 bg-gray-50 border border-gray-200 rounded-xl p-3 text-xs text-gray-600 font-mono shadow-sm">
        <input
          type="text"
          value={gatewayUrl}
          onChange={(e) => setGatewayUrl(e.target.value)}
          onBlur={() => { saveQuickConfig({ gatewayUrl }).catch(silentErrorHandler('ModelsAPI')); }}
          className="w-full bg-transparent border-none outline-none"
        />
        <input
          type="password"
          value={gatewayToken}
          onChange={(e) => setGatewayToken(e.target.value)}
          onBlur={() => { saveQuickConfig({ gatewayToken }).catch(silentErrorHandler('ModelsAPI')); }}
          placeholder="Gateway auth token"
          className="w-full bg-transparent border-none outline-none"
        />
      </div>
    </div>
  );
}