/** @odoo-module **/

import { patch } from "@web/core/utils/patch";
import { PDFIframe } from "@sign/components/sign_request/PDF_iframe";
import { SignablePDFIframe } from "@sign/components/sign_request/signable_PDF_iframe";

console.log("Sign Image Field: Initializing stabilized patches...");

/**
 * Shared utility for lazy loading image fields.
 */
const triggerLazyLoad = (el) => {
    if (!el) return;
    const lazyImg = el.querySelector('.o_sign_image_lazy');
    if (lazyImg && (lazyImg.dataset.src || lazyImg.src)) {
        const targetSrc = lazyImg.dataset.src || lazyImg.src;
        const currentSrc = lazyImg.getAttribute('src');
        
        // Only trigger if we haven't loaded the real image yet
        if (!currentSrc || currentSrc.startsWith('data:image/gif') || currentSrc === '') {
            lazyImg.src = targetSrc;
            lazyImg.onload = () => {
                lazyImg.classList.remove('o_sign_image_loading');
                el.classList.remove('o_sign_image_loading_container');
                lazyImg.style.opacity = 1;
            };
        } else {
            // Cleanup in case of re-rendering
            lazyImg.classList.remove('o_sign_image_loading');
            el.classList.remove('o_sign_image_loading_container');
            lazyImg.style.opacity = 1;
        }
    }
};

/**
 * Shared logic for setting up an observer on any image field.
 */
const setupLazyObserver = (el) => {
    if (!el) return;
    
    // Immediate check + safety fallback (2 seconds)
    // This ensures images load even if IntersectionObserver is throttled
    setTimeout(() => triggerLazyLoad(el), 2000);

    if (window.IntersectionObserver) {
        const observer = new IntersectionObserver((entries) => {
            entries.forEach(entry => {
                if (entry.isIntersecting) {
                    triggerLazyLoad(el);
                    observer.disconnect();
                }
            });
        }, { rootMargin: '200px' });
        observer.observe(el);
    } else {
        triggerLazyLoad(el);
    }
};

// 1. Patch PDFIframe (Used for observers and read-only views)
patch(PDFIframe.prototype, {
    enableCustom(signItem) {
        // ALWAYS call the base implementation FIRST to preserve Odoo behavior
        super.enableCustom(...arguments);
        
        // OUR LOGIC: Setup lazy loading if it's an image
        if (signItem && signItem.data && signItem.data.type === 'image' && signItem.el) {
            setupLazyObserver(signItem.el);
        }
    }
});

// 2. Patch SignablePDFIframe (Used for active signers)
patch(SignablePDFIframe.prototype, {
    enableCustom(signItem) {
        // ALWAYS call the base implementation FIRST to preserve text/signature population
        super.enableCustom(...arguments);
        
        // OUR LOGIC: Setup lazy loading and upload support
        if (signItem && signItem.data && signItem.data.type === 'image' && signItem.el) {
            const el = signItem.el;
            const data = signItem.data;
            
            // Shared lazy loading observer
            setupLazyObserver(el);
            
            // Only attach upload listeners if this person is responsible and not readonly
            if (this.readonly || (data.responsible > 0 && data.responsible !== this.currentRole)) {
                return;
            }

            el.setAttribute('data-type', 'image');
            const input = el.querySelector('.o_sign_image_upload_input');
            if (input) {
                el.addEventListener('click', (e) => {
                    if (e.target !== input) {
                        input.click();
                    }
                });

                input.addEventListener('change', (e) => {
                    const file = e.target.files[0];
                    if (!file) return;

                    const reader = new FileReader();
                    reader.onload = (readerEvent) => {
                        const img = new Image();
                        img.onload = () => {
                            const canvas = document.createElement('canvas');
                            let width = img.width;
                            let height = img.height;
                            const MAX_SIZE = 1080;
                            if (width > height) {
                                if (width > MAX_SIZE) {
                                    height *= MAX_SIZE / width;
                                    width = MAX_SIZE;
                                }
                            } else if (height > MAX_SIZE) {
                                width *= MAX_SIZE / height;
                                height = MAX_SIZE;
                            }
                            canvas.width = width;
                            canvas.height = height;
                            const ctx = canvas.getContext('2d');
                            ctx.drawImage(img, 0, 0, width, height);

                            const compressedDataUrl = canvas.toDataURL('image/jpeg', 0.7);
                            data.value = compressedDataUrl;
                            el.dataset.value = compressedDataUrl;

                            const placeholder = el.querySelector('.o_placeholder');
                            if (placeholder) placeholder.remove();

                            let existingImg = el.querySelector('img');
                            if (!existingImg) {
                                existingImg = document.createElement('img');
                                existingImg.style.maxWidth = '100%';
                                existingImg.style.maxHeight = '100%';
                                existingImg.style.objectFit = 'contain';
                                const body = el.querySelector('.sign_item_body') || el;
                                body.appendChild(existingImg);
                            }
                            existingImg.src = compressedDataUrl;

                            if (this.handleInput) {
                                this.handleInput();
                            }
                        };
                        img.src = readerEvent.target.result;
                    };
                    reader.readAsDataURL(file);
                });
            }
        }
    },

    getSignatureValueFromElement(item) {
        if (item.data.type === 'image') {
            return item.el.dataset.value || item.data.value || false;
        }
        return super.getSignatureValueFromElement(...arguments);
    }
});