import 'package:flutter/material.dart';
import 'package:google_fonts/google_fonts.dart';
import 'package:trainhub_flutter/core/constants/ui_constants.dart';
import 'package:trainhub_flutter/core/theme/app_colors.dart';
import 'package:trainhub_flutter/data/services/ai_settings_service.dart';
import 'package:trainhub_flutter/injection.dart';

/// Lets the user pick which AI backend answers chat: the bundled local model
/// or a cloud API (Anthropic / OpenAI / Gemini) with their own key.
class AiProviderSection extends StatefulWidget {
  const AiProviderSection({super.key});

  @override
  State<AiProviderSection> createState() => _AiProviderSectionState();
}

class _AiProviderSectionState extends State<AiProviderSection> {
  late final AiSettingsService _service = getIt<AiSettingsService>();
  late AiProvider _provider;
  late final TextEditingController _apiKeyController;
  late final TextEditingController _modelController;
  late final TextEditingController _baseUrlController;
  bool _obscureKey = true;
  bool _saved = false;

  @override
  void initState() {
    super.initState();
    _provider = _service.settings.provider;
    _apiKeyController = TextEditingController(
      text: _service.settings.apiKeys[_provider.name] ?? '',
    );
    _modelController = TextEditingController(
      text: _service.settings.modelFor(_provider),
    );
    _baseUrlController = TextEditingController(
      text: _service.settings.baseUrlFor(_provider),
    );
  }

  @override
  void dispose() {
    _apiKeyController.dispose();
    _modelController.dispose();
    _baseUrlController.dispose();
    super.dispose();
  }

  void _onProviderChanged(AiProvider? provider) {
    if (provider == null) return;
    setState(() {
      _provider = provider;
      _apiKeyController.text = _service.settings.apiKeys[provider.name] ?? '';
      _modelController.text = _service.settings.modelFor(provider);
      _baseUrlController.text = _service.settings.baseUrlFor(provider);
      _saved = false;
    });
  }

  Future<void> _save() async {
    final settings = _service.settings;
    await _service.save(
      settings.copyWith(
        provider: _provider,
        apiKeys: {
          ...settings.apiKeys,
          _provider.name: _apiKeyController.text.trim(),
        },
        models: {
          ...settings.models,
          _provider.name: _modelController.text.trim(),
        },
        baseUrls: {
          ...settings.baseUrls,
          _provider.name: _baseUrlController.text.trim(),
        },
      ),
    );
    if (mounted) setState(() => _saved = true);
  }

  @override
  Widget build(BuildContext context) {
    return Container(
      decoration: BoxDecoration(
        color: AppColors.surfaceContainer,
        borderRadius: UIConstants.cardBorderRadius,
        border: Border.all(color: AppColors.border),
      ),
      child: Column(
        crossAxisAlignment: CrossAxisAlignment.start,
        children: [
          Padding(
            padding: const EdgeInsets.all(UIConstants.spacing16),
            child: Row(
              children: [
                const Icon(
                  Icons.cloud_outlined,
                  size: 18,
                  color: AppColors.accent,
                ),
                const SizedBox(width: 10),
                Text(
                  'AI PROVIDER',
                  style: GoogleFonts.chakraPetch(
                    fontSize: 14,
                    fontWeight: FontWeight.w600,
                    letterSpacing: 1,
                    color: AppColors.textPrimary,
                  ),
                ),
              ],
            ),
          ),
          const Divider(height: 1, color: AppColors.border),
          Padding(
            padding: const EdgeInsets.all(UIConstants.spacing16),
            child: Column(
              crossAxisAlignment: CrossAxisAlignment.start,
              children: [
                Text(
                  'Chat backend. The knowledge base always uses the local '
                  'embedding model — your notes never leave this machine. '
                  'With a cloud provider, chat messages plus your exercise '
                  'and plan names are sent to that provider.',
                  style: GoogleFonts.inter(
                    fontSize: 12,
                    color: AppColors.textSecondary,
                    height: 1.5,
                  ),
                ),
                const SizedBox(height: UIConstants.spacing16),
                DropdownButtonFormField<AiProvider>(
                  initialValue: _provider,
                  onChanged: _onProviderChanged,
                  dropdownColor: AppColors.surfaceContainerHigh,
                  style: GoogleFonts.inter(
                    fontSize: 13,
                    color: AppColors.textPrimary,
                  ),
                  decoration: const InputDecoration(labelText: 'Provider'),
                  items: [
                    for (final p in AiProvider.values)
                      DropdownMenuItem(value: p, child: Text(p.label)),
                  ],
                ),
                if (_provider.isSelfHosted) ...[
                  const SizedBox(height: UIConstants.spacing12),
                  TextField(
                    controller: _baseUrlController,
                    onChanged: (_) => setState(() => _saved = false),
                    style: GoogleFonts.jetBrainsMono(
                      fontSize: 12,
                      color: AppColors.textPrimary,
                    ),
                    decoration: InputDecoration(
                      labelText: 'Server URL',
                      helperText: 'Default: ${_provider.defaultBaseUrl}',
                      helperStyle: GoogleFonts.inter(
                        fontSize: 11,
                        color: AppColors.textMuted,
                      ),
                    ),
                  ),
                ],
                if (_provider.needsApiKey) ...[
                  const SizedBox(height: UIConstants.spacing12),
                  TextField(
                    controller: _apiKeyController,
                    obscureText: _obscureKey,
                    onChanged: (_) => setState(() => _saved = false),
                    style: GoogleFonts.jetBrainsMono(
                      fontSize: 12,
                      color: AppColors.textPrimary,
                    ),
                    decoration: InputDecoration(
                      labelText: 'API key',
                      suffixIcon: IconButton(
                        icon: Icon(
                          _obscureKey
                              ? Icons.visibility_outlined
                              : Icons.visibility_off_outlined,
                          size: 16,
                        ),
                        onPressed: () =>
                            setState(() => _obscureKey = !_obscureKey),
                      ),
                    ),
                  ),
                ],
                if (_provider != AiProvider.local) ...[
                  const SizedBox(height: UIConstants.spacing12),
                  TextField(
                    controller: _modelController,
                    onChanged: (_) => setState(() => _saved = false),
                    style: GoogleFonts.jetBrainsMono(
                      fontSize: 12,
                      color: AppColors.textPrimary,
                    ),
                    decoration: InputDecoration(
                      labelText: 'Model',
                      helperText: _provider == AiProvider.ollama
                          ? 'Name of a model pulled in Ollama, '
                                'e.g. qwen3:4b, llama3.1'
                          : 'Default: ${_provider.defaultModel}',
                      helperStyle: GoogleFonts.inter(
                        fontSize: 11,
                        color: AppColors.textMuted,
                      ),
                    ),
                  ),
                ],
                const SizedBox(height: UIConstants.spacing16),
                Row(
                  children: [
                    FilledButton(onPressed: _save, child: const Text('SAVE')),
                    if (_saved) ...[
                      const SizedBox(width: UIConstants.spacing12),
                      const Icon(
                        Icons.check_circle_outline,
                        size: 16,
                        color: AppColors.success,
                      ),
                      const SizedBox(width: 6),
                      Text(
                        'Saved',
                        style: GoogleFonts.inter(
                          fontSize: 12,
                          color: AppColors.success,
                        ),
                      ),
                    ],
                  ],
                ),
              ],
            ),
          ),
        ],
      ),
    );
  }
}