import { useState, useEffect } from 'react';
import { Alert } from 'react-native';
import { router } from 'expo-router';
import { generateImage } from '~/services/imageGeneration';
import { useAuth } from '~/contexts/AuthContext';
import { useModelSelection } from '~/store/modelStore';
import { useTagStore, Tag } from '~/store/tagStore';
import { usePromptStore } from '~/store/promptStore';
import { useGenerationDefaults } from '~/store/generationDefaultsStore';
import { useGeneratingImagesStore } from '~/store/generatingImagesStore';

// Define aspect ratios with common presets
export const aspectRatios = [
  { label: '1:1', value: '1:1', width: 1024, height: 1024, icon: '⬜' },
  { label: '16:9', value: '16:9', width: 1344, height: 768, icon: '📺' },
  { label: '9:16', value: '9:16', width: 768, height: 1344, icon: '📱' },
  { label: '4:3', value: '4:3', width: 1152, height: 896, icon: '🖼️' },
  { label: '3:4', value: '3:4', width: 896, height: 1152, icon: '📷' },
  { label: '3:2', value: '3:2', width: 1216, height: 832, icon: '🎞️' },
  { label: '2:3', value: '2:3', width: 832, height: 1216, icon: '📸' },
  { label: '21:9', value: '21:9', width: 1536, height: 640, icon: '🎬' },
  { label: '9:21', value: '9:21', width: 640, height: 1536, icon: '📲' },
];

export function useImageGeneration() {
  const { user } = useAuth();
  const { prompt, setPrompt } = usePromptStore();
  const [isGenerating, setIsGenerating] = useState(false);

  // Get generation defaults
  const {
    defaultModelId,
    defaultAspectRatio,
  } = useGenerationDefaults();

  // Initialize with defaults
  const defaultRatio = aspectRatios.find(r => r.value === defaultAspectRatio) || aspectRatios[0];

  const [selectedAspectRatio, setSelectedAspectRatio] = useState(defaultRatio);
  const [selectedTags, setSelectedTags] = useState<Tag[]>([]);
  const [width, setWidth] = useState(defaultRatio.width);
  const [height, setHeight] = useState(defaultRatio.height);
  const [steps, setSteps] = useState(4);
  const [guidanceScale, setGuidanceScale] = useState(3.5);

  // Model selection
  const {
    models,
    selectedModel,
    isLoading: loadingModels,
    error: modelError,
    hasModels,
    setSelectedModel,
    loadModels,
    clearError
  } = useModelSelection();

  // Tag management
  const { addTagsToImage } = useTagStore();

  // Models are now preloaded at app start in _layout.tsx
  // Only load if we somehow don't have models (e.g., after error)
  useEffect(() => {
    if (!loadingModels && !hasModels && !modelError) {
      const initModels = async () => {
        try {
          await loadModels();
        } catch (error) {
          console.error('Failed to load models initially:', error);
        }
      };
      initModels();
    }
  }, [loadingModels, hasModels, modelError]);

  // Set default model when models are loaded
  useEffect(() => {
    if (defaultModelId && models.length > 0 && !selectedModel) {
      const defaultModel = models.find(m => m.id === defaultModelId);
      if (defaultModel) {
        setSelectedModel(defaultModel);
      }
    }
  }, [defaultModelId, models, selectedModel]);

  useEffect(() => {
    if (selectedModel) {
      setSteps(selectedModel.default_steps);
      setGuidanceScale(selectedModel.default_guidance_scale);
      
      const maxDimension = Math.min(selectedModel.max_width, selectedModel.max_height);
      const minDimension = Math.max(selectedModel.min_width, selectedModel.min_height);
      
      let newWidth = selectedAspectRatio.width;
      let newHeight = selectedAspectRatio.height;
      
      if (newWidth > maxDimension || newHeight > maxDimension) {
        const scale = maxDimension / Math.max(newWidth, newHeight);
        newWidth = Math.round(newWidth * scale);
        newHeight = Math.round(newHeight * scale);
      }
      
      if (newWidth < minDimension || newHeight < minDimension) {
        const scale = minDimension / Math.min(newWidth, newHeight);
        newWidth = Math.round(newWidth * scale);
        newHeight = Math.round(newHeight * scale);
      }
      
      setWidth(newWidth);
      setHeight(newHeight);
    }
  }, [selectedModel, selectedAspectRatio]);

  useEffect(() => {
    setWidth(selectedAspectRatio.width);
    setHeight(selectedAspectRatio.height);
  }, [selectedAspectRatio]);

  const { addGeneratingImage, completeGeneratingImage, failGeneratingImage } = useGeneratingImagesStore();

  const handleGenerate = async (options?: {
    navigateToGallery?: boolean;
    onSuccess?: (generationTime: number) => void;
  }) => {
    if (!prompt.trim()) {
      Alert.alert('Fehler', 'Bitte gib einen Prompt ein');
      return;
    }

    if (!user) {
      Alert.alert('Fehler', 'Du musst angemeldet sein');
      return;
    }

    if (!selectedModel) {
      Alert.alert('Fehler', 'Bitte wähle ein Modell aus');
      return;
    }

    setIsGenerating(true);

    // Add optimistic placeholder image IMMEDIATELY
    const tempId = addGeneratingImage({
      prompt: prompt.trim(),
      model_id: selectedModel.id,
      width,
      height,
    });

    // Navigate to gallery IMMEDIATELY
    if (options?.navigateToGallery !== false) {
      router.push('/(tabs)');
    }

    try {
      // Generate image in background
      const result = await generateImage({
        prompt: prompt.trim(),
        model_id: selectedModel.id,
        width,
        height,
        steps,
        guidance_scale: guidanceScale,
      });

      // Add tags if needed
      if (result.image?.id && selectedTags.length > 0) {
        await addTagsToImage(result.image.id, selectedTags.map(tag => tag.id));
      }

      // Mark as completed with real image data
      completeGeneratingImage(tempId, result.image, result.generation_time);

      // Clear form
      setPrompt('');
      setSelectedTags([]);

      // Call success callback with generation time
      options?.onSuccess?.(result.generation_time);

    } catch (error: any) {
      console.error('Generation error:', error);

      // Mark as failed
      failGeneratingImage(tempId, error.message || 'Generation failed');

      Alert.alert(
        'Fehler bei der Generierung',
        error.message || 'Etwas ist schiefgelaufen. Bitte versuche es erneut.'
      );
    } finally {
      setIsGenerating(false);
    }
  };

  const resetForm = () => {
    setPrompt('');
    setSelectedTags([]);
    setSelectedAspectRatio(aspectRatios[0]);
  };

  return {
    // State
    prompt,
    setPrompt,
    isGenerating,
    selectedAspectRatio,
    setSelectedAspectRatio,
    selectedTags,
    setSelectedTags,
    width,
    height,
    steps,
    setSteps,
    guidanceScale,
    setGuidanceScale,
    
    // Model management
    models,
    selectedModel,
    loadingModels,
    modelError,
    hasModels,
    setSelectedModel,
    loadModels,
    clearError,
    
    // Actions
    handleGenerate,
    resetForm,
  };
}