import { useState, useCallback } from 'react';
import { ToastMessage } from './useToasts';
import { dataURLtoBlob, calculateSHA256, copyToClipboard } from '../utils/canvasUtils';
import { CanvasHistoryHook } from './useCanvasHistory';

const SHARE_API_URL = 'https://sharefile.suisuy.eu.org';
const ASK_API_URL = 'https://getai.deno.dev/';
const MAX_UPLOAD_SIZE_BYTES = 50 * 1024 * 1024; // 50MB

export type AiImageQuality = 'low' | 'medium' | 'hd';
export type AiDimensionsMode = 'api_default' | 'match_canvas' | 'fixed_1024';

interface AiFeaturesHook {
  isMagicUploading: boolean;
  showAiEditModal: boolean;
  aiPrompt: string;
  isGeneratingAiImage: boolean;
  sharedImageUrlForAi: string | null;
  aiEditError: string | null;
  isAskingAi: boolean;
  askUrl: string | null;
  handleMagicUpload: () => Promise<void>;
  handleGenerateAiImage: () => Promise<void>;
  handleAskAi: () => Promise<void>;
  handleCancelAiEdit: () => void;
  setAiPrompt: React.Dispatch<React.SetStateAction<string>>;
  clearAskUrl: () => void;
}

interface UseAiFeaturesProps {
  currentDataURL: string | null;
  showToast: (message: string, type: ToastMessage['type']) => void;
  updateCanvasState: CanvasHistoryHook['updateCanvasState'];
  setZoomLevel: (zoom: number) => void; 
  aiImageQuality: AiImageQuality;
  aiApiEndpoint: string;
  aiDimensionsMode: AiDimensionsMode;
  currentCanvasWidth: number; 
  currentCanvasHeight: number; 
}

export const useAiFeatures = ({
  currentDataURL,
  showToast,
  updateCanvasState,
  setZoomLevel, 
  aiImageQuality,
  aiApiEndpoint,
  aiDimensionsMode,
  currentCanvasWidth, 
  currentCanvasHeight, 
}: UseAiFeaturesProps): AiFeaturesHook => {
  const [isMagicUploading, setIsMagicUploading] = useState<boolean>(false);
  const [showAiEditModal, setShowAiEditModal] = useState<boolean>(false);
  const [aiPrompt, setAiPrompt] = useState<string>('');
  const [isGeneratingAiImage, setIsGeneratingAiImage] = useState<boolean>(false);
  const [sharedImageUrlForAi, setSharedImageUrlForAi] = useState<string | null>(null);
  const [aiEditError, setAiEditError] = useState<string | null>(null);
  const [isAskingAi, setIsAskingAi] = useState<boolean>(false);
  const [askUrl, setAskUrl] = useState<string | null>(null);

  const clearAskUrl = useCallback(() => {
    setAskUrl(null);
  }, []);

  const loadAiImageOntoCanvas = useCallback((aiImageDataUrl: string) => {
    const img = new Image();
    img.onload = () => {
        const tempCanvas = document.createElement('canvas');
        tempCanvas.width = currentCanvasWidth;
        tempCanvas.height = currentCanvasHeight;
        const tempCtx = tempCanvas.getContext('2d');

        if (tempCtx) {
            // Fill background (e.g., white)
            tempCtx.fillStyle = '#FFFFFF';
            tempCtx.fillRect(0, 0, currentCanvasWidth, currentCanvasHeight);

            let drawWidth = img.naturalWidth;
            let drawHeight = img.naturalHeight;

            // Scale image if it's larger than the canvas, preserving aspect ratio
            if (img.naturalWidth > currentCanvasWidth || img.naturalHeight > currentCanvasHeight) {
                const aspectRatio = img.naturalWidth / img.naturalHeight;
                if (currentCanvasWidth / aspectRatio <= currentCanvasHeight) {
                    drawWidth = currentCanvasWidth;
                    drawHeight = currentCanvasWidth / aspectRatio;
                } else {
                    drawHeight = currentCanvasHeight;
                    drawWidth = currentCanvasHeight * aspectRatio;
                }
            }
            
            // Ensure dimensions are at least 1px
            drawWidth = Math.max(1, Math.floor(drawWidth));
            drawHeight = Math.max(1, Math.floor(drawHeight));

            // Change: Draw image at top-left (0,0)
            const drawX = 0;
            const drawY = 0;

            tempCtx.drawImage(img, drawX, drawY, drawWidth, drawHeight);
            
            const newCanvasState = tempCanvas.toDataURL('image/png');

            // Update canvas state with the new image, but keep original canvas dimensions
            updateCanvasState(newCanvasState, currentCanvasWidth, currentCanvasHeight);

            setShowAiEditModal(false);
            showToast('AI image applied to canvas!', 'success');
            setAiPrompt(''); 
            setSharedImageUrlForAi(null);
        } else {
            setAiEditError('Failed to create drawing context for AI image.');
        }
        setIsGeneratingAiImage(false);
    };
    img.onerror = () => {
        setAiEditError('Failed to load the generated AI image. It might be an invalid image format.');
        setIsGeneratingAiImage(false);
    };
    img.crossOrigin = "anonymous"; 
    img.src = aiImageDataUrl;
  }, [showToast, updateCanvasState, currentCanvasWidth, currentCanvasHeight]);

  const handleMagicUpload = useCallback(async () => {
    if (isMagicUploading || !currentDataURL) {
        showToast('No canvas content to share.', 'info');
        return;
    }

    setIsMagicUploading(true);
    setAiEditError(null);
    showToast('Uploading image...', 'info');

    try {
        const blob = await dataURLtoBlob(currentDataURL);

        if (blob.size > MAX_UPLOAD_SIZE_BYTES) {
            showToast(`Image too large (${(blob.size / 1024 / 1024).toFixed(2)}MB). Max 50MB.`, 'error');
            setIsMagicUploading(false);
            return;
        }

        const hash = await calculateSHA256(blob);
        const filename = `tempaint_${hash}.png`;
        const uploadUrl = `${SHARE_API_URL}/${filename}`;

        const response = await fetch(uploadUrl, {
            method: 'POST',
            headers: { 'Content-Type': blob.type || 'image/png' },
            body: blob,
        });

        if (!response.ok) {
            let errorMsg = `Upload failed: ${response.statusText}`;
            try { const errorBody = await response.text(); errorMsg = `Upload failed: ${errorBody || response.statusText}`; } catch (e) { /* ignore */ }
            throw new Error(errorMsg);
        }

        const returnedObjectName = await response.text();
        const finalShareUrl = `https://pub-cb2c87ea7373408abb1050dd43e3cd8e.r2.dev/${returnedObjectName}`;
        
        setSharedImageUrlForAi(finalShareUrl);
        setShowAiEditModal(true); 
        setAiPrompt(''); 
        setAiEditError(null);
        clearAskUrl();

    } catch (error: any) {
        console.error('Magic upload error:', error);
        showToast(error.message || 'Magic upload failed. Check console.', 'error');
    } finally {
        setIsMagicUploading(false); 
    }
  }, [isMagicUploading, currentDataURL, showToast, clearAskUrl]);

  const handleGenerateAiImage = useCallback(async () => {
    if (!aiPrompt.trim() || !sharedImageUrlForAi) {
      setAiEditError('Please enter a prompt and ensure an image was uploaded.');
      return;
    }
    setIsGeneratingAiImage(true);
    setAiEditError(null);
    clearAskUrl();
    showToast('Generating AI image...', 'info');

    const encodedPrompt = encodeURIComponent(aiPrompt);
    const encodedImageUrl = encodeURIComponent(sharedImageUrlForAi);
    
    let finalApiUrl = aiApiEndpoint
        .replace('{prompt}', encodedPrompt)
        .replace('{imgurl.url}', encodedImageUrl);
        
    if (finalApiUrl.includes('{quality}')) {
        finalApiUrl = finalApiUrl.replace('{quality}', aiImageQuality);
    }

    if (finalApiUrl.includes('{size_params}')) {
        let sizeParamsString = '';
        if (aiDimensionsMode === 'match_canvas') {
            sizeParamsString = `&width=${currentCanvasWidth}&height=${currentCanvasHeight}`;
        } else if (aiDimensionsMode === 'fixed_1024') {
            sizeParamsString = `&width=1024&height=1024`;
        }
        finalApiUrl = finalApiUrl.replace('{size_params}', sizeParamsString);
    }
    
    try {
      const response = await fetch(finalApiUrl);
      if (!response.ok) {
        let errorMsg = `AI image generation failed: ${response.status} ${response.statusText}`;
        try {
            const errorBody = await response.text(); 
            if (errorBody && !errorBody.toLowerCase().includes('<html')) {
                 errorMsg += ` - ${errorBody.substring(0,100)}`;
            }
        } catch(e) { /* ignore if can't read body */ }
        throw new Error(errorMsg);
      }
      
      const imageBlob = await response.blob();
      if (!imageBlob.type.startsWith('image/')) {
        throw new Error('AI service did not return a valid image. Please try a different prompt or check the API endpoint.');
      }

      const reader = new FileReader();
      reader.onloadend = () => {
        if (typeof reader.result === 'string') {
          loadAiImageOntoCanvas(reader.result);
        } else {
          setAiEditError('Failed to read AI image data as string.');
          setIsGeneratingAiImage(false);
        }
      };
      reader.onerror = () => {
        setAiEditError('Failed to read AI image data.');
        setIsGeneratingAiImage(false);
      }
      reader.readAsDataURL(imageBlob);

    } catch (error: any) {
      console.error('AI image generation error:', error);
      setAiEditError(error.message || 'An unknown error occurred during AI image generation.');
      setIsGeneratingAiImage(false);
    }
  }, [aiPrompt, sharedImageUrlForAi, showToast, loadAiImageOntoCanvas, aiImageQuality, aiApiEndpoint, aiDimensionsMode, currentCanvasWidth, currentCanvasHeight, clearAskUrl]);

  const handleAskAi = useCallback(async () => {
    if (!aiPrompt.trim() || !sharedImageUrlForAi) {
      setAiEditError('Please enter a question about the image.');
      return;
    }
    setIsAskingAi(true);
    setAiEditError(null);
    setAskUrl(null); // Clear previous URL first

    try {
        const encodedPrompt = encodeURIComponent(aiPrompt);
        const encodedImageUrl = encodeURIComponent(sharedImageUrlForAi);
        const finalAskUrl = `${ASK_API_URL}?q=${encodedPrompt}&image=${encodedImageUrl}`;
        setAskUrl(finalAskUrl);

    } catch (error: any) {
        console.error('AI ask error:', error);
        setAiEditError(error.message || 'An unknown error occurred while asking AI.');
    } finally {
        setIsAskingAi(false);
    }
  }, [aiPrompt, sharedImageUrlForAi]);
  

  const handleCancelAiEdit = () => {
    setShowAiEditModal(false);
    if (sharedImageUrlForAi) {
        copyToClipboard(sharedImageUrlForAi, (msg, type) => showToast(msg,type as 'info' | 'error')).then(copied => {
            if(copied) {
                 showToast(`Image uploaded! URL: ${sharedImageUrlForAi} (Copied!)`, 'success');
            }
        });
    }
    setAiPrompt('');
    setAiEditError(null);
    setSharedImageUrlForAi(null);
    clearAskUrl();
  };

  return {
    isMagicUploading,
    showAiEditModal,
    aiPrompt,
    isGeneratingAiImage,
    sharedImageUrlForAi,
    aiEditError,
    isAskingAi,
    askUrl,
    handleMagicUpload,
    handleGenerateAiImage,
    handleAskAi,
    handleCancelAiEdit,
    setAiPrompt,
    clearAskUrl,
  };
};