// Customer attachment gestures and image viewing; upload ownership stays on the server.
var ChatAttachments = {
    bindUpload(options){
        const zone = options.zone, hint = options.hint;
        let dragDepth = 0;
        function hasFiles(event){
            return event.dataTransfer && Array.from(event.dataTransfer.types || []).includes('Files');
        }
        function clearDrag(){ dragDepth = 0; hint.hidden = true; }
        function hasFolder(data){
            return Array.from(data.items || []).some(function(item){
                const entry = typeof item.webkitGetAsEntry === 'function' ? item.webkitGetAsEntry() : null;
                return entry && entry.isDirectory;
            });
        }
        function accept(files){
            if(!files.length) return;
            if(files.length !== 1){ options.status(options.text('singleAttachment'), true); return; }
            options.upload(files[0]);
        }
        options.input.addEventListener('paste', function(event){
            const data = event.clipboardData;
            if(!data) return;
            if(hasFolder(data)){
                event.preventDefault();
                options.status(options.text('folderAttachment'), true);
                return;
            }
            let files = Array.from(data.files || []);
            if(!files.length){
                files = Array.from(data.items || []).filter(item=>item.kind === 'file').map(item=>item.getAsFile()).filter(Boolean);
            }
            if(!files.length) return;
            event.preventDefault();
            accept(files);
        });
        zone.addEventListener('dragenter', function(event){
            if(!hasFiles(event)) return;
            event.preventDefault();
            dragDepth += 1;
            hint.hidden = false;
        });
        zone.addEventListener('dragover', function(event){
            if(!hasFiles(event)) return;
            event.preventDefault();
            event.dataTransfer.dropEffect = 'copy';
        });
        zone.addEventListener('dragleave', function(event){
            if(!dragDepth) return;
            dragDepth = Math.max(0, dragDepth - 1);
            if(!dragDepth) clearDrag();
        });
        zone.addEventListener('drop', function(event){
            clearDrag();
            if(!hasFiles(event)) return;
            event.preventDefault();
            if(hasFolder(event.dataTransfer)){
                options.status(options.text('folderAttachment'), true);
                return;
            }
            accept(Array.from(event.dataTransfer.files || []));
        });
        // Dropping outside the chat must not navigate away and lose a draft.
        document.addEventListener('dragover', function(event){ if(hasFiles(event)) event.preventDefault(); });
        document.addEventListener('drop', function(event){
            clearDrag();
            if(hasFiles(event)) event.preventDefault();
        });
        document.addEventListener('dragend', clearDrag);
        window.addEventListener('blur', clearDrag);
        return {clear:clearDrag};
    },
    createViewer(options){
        let active = null;
        function close(){ if(active) active.close(); }
        function open(source, trigger){
            if(source.hidden || source.dataset.unavailable) return;
            close();
            const dialog = document.createElement('dialog');
            dialog.className = 'image-viewer';
            dialog.setAttribute('aria-label', options.text('imagePreview'));
            const header = document.createElement('div');
            header.className = 'image-viewer-header';
            const title = document.createElement('h2');
            title.textContent = options.text('imagePreview');
            header.appendChild(title);
            const controls = document.createElement('div');
            controls.className = 'image-viewer-controls';
            header.appendChild(controls);
            const stage = document.createElement('div');
            stage.className = 'image-viewer-stage';
            const image = document.createElement('img');
            image.alt = source.alt || options.text('imagePreview');
            const status = document.createElement('p');
            status.className = 'image-viewer-status';
            status.setAttribute('role', 'status');
            status.textContent = options.text('imageLoading');
            stage.appendChild(image);
            stage.appendChild(status);
            dialog.appendChild(header);
            dialog.appendChild(stage);
            let scale = 1, loaded = false, finished = false;
            function button(key, action){
                const control = document.createElement('button');
                control.type = 'button';
                control.textContent = options.text(key);
                control.setAttribute('aria-label', options.text(key));
                control.onclick = action;
                controls.appendChild(control);
                return control;
            }
            const smaller = button('imageZoomOut', ()=>zoom(scale - .5));
            const larger = button('imageZoomIn', ()=>zoom(scale + .5));
            const fit = button('imageFit', ()=>zoom(1));
            const dismiss = button('imageClose', ()=>dialog.close());
            function zoom(next){
                scale = Math.max(1, Math.min(3, next));
                smaller.disabled = !loaded || scale <= 1;
                larger.disabled = !loaded || scale >= 3;
                fit.disabled = !loaded;
                if(!loaded) return;
                const ratio = Math.min(1, Math.max(1, stage.clientWidth - 32) / image.naturalWidth,
                    Math.max(1, stage.clientHeight - 32) / image.naturalHeight);
                image.style.width = Math.round(image.naturalWidth * ratio * scale) + 'px';
                image.style.height = Math.round(image.naturalHeight * ratio * scale) + 'px';
            }
            function resized(){ zoom(scale); }
            function cleanup(){
                if(finished) return;
                finished = true;
                window.removeEventListener('resize', resized);
                dialog.remove();
                if(active === dialog){
                    active = null;
                    if(trigger.isConnected) trigger.focus({preventScroll:true});
                }
            }
            dialog.addEventListener('close', cleanup);
            dialog.addEventListener('cancel', function(event){ event.preventDefault(); dialog.close(); });
            dialog.addEventListener('click', function(event){ if(event.target === dialog) dialog.close(); });
            image.onload = function(){ loaded = true; status.hidden = true; zoom(1); };
            image.onerror = function(){
                loaded = false;
                image.hidden = true;
                status.hidden = false;
                status.textContent = options.text('attachmentUnavailable');
                zoom(1);
            };
            zoom(1);
            document.body.appendChild(dialog);
            active = dialog;
            dialog.showModal();
            dismiss.focus({preventScroll:true});
            image.src = source.currentSrc || source.src;
            window.addEventListener('resize', resized);
        }
        options.container.addEventListener('click', function(event){
            if(event.ctrlKey || event.metaKey || event.shiftKey || event.altKey || event.button > 0) return;
            const trigger = event.target.closest('a, .image-preview-trigger');
            if(!trigger) return;
            const source = trigger.querySelector('img');
            if(!source || (!source.classList.contains('message-image') && !trigger.classList.contains('image-preview-trigger'))) return;
            event.preventDefault();
            open(source, trigger);
        });
        return {close:close};
    }
};