window.Upload = {
    frontFile: null,
    backFile: null,
    isProcessing: false,

    init: function () {
        var self = this;

        // Doc type selector — show/hide back upload
        var docTypeSelect = Utils.$('#doc-type-select');
        docTypeSelect.addEventListener('change', function () {
            self._updateLayout();
            self._updateProcessButton();
        });

        // Front drop zone
        this._setupDropZone('front');
        // Back drop zone
        this._setupDropZone('back');

        // Process button
        Utils.$('#btn-process').addEventListener('click', function () {
            self.processDocument();
        });

        this._updateLayout();
    },

    _setupDropZone: function (side) {
        var self = this;
        var dropZone = Utils.$('#drop-zone-' + side);
        var fileInput = Utils.$('#file-input-' + side);

        // Click to browse (skip in camera-only mode)
        dropZone.addEventListener('click', function (e) {
            if (e.target.classList.contains('btn-remove')) return;
            if (e.target.classList.contains('btn-camera')) return;
            if (dropZone.classList.contains('camera-only')) return;
            if (!self.isProcessing) fileInput.click();
        });
        dropZone.addEventListener('keydown', function (e) {
            if (e.key === 'Enter' || e.key === ' ') {
                e.preventDefault();
                if (dropZone.classList.contains('camera-only')) return;
                if (!self.isProcessing) fileInput.click();
            }
        });

        // File input change
        fileInput.addEventListener('change', function () {
            if (fileInput.files.length > 0) {
                self._setFile(side, fileInput.files[0]);
            }
            fileInput.value = '';
        });

        // Drag and drop
        dropZone.addEventListener('dragover', function (e) {
            e.preventDefault();
            if (!dropZone.classList.contains('camera-only')) {
                dropZone.classList.add('drag-active');
            }
        });
        dropZone.addEventListener('dragleave', function () {
            dropZone.classList.remove('drag-active');
        });
        dropZone.addEventListener('drop', function (e) {
            e.preventDefault();
            dropZone.classList.remove('drag-active');
            if (dropZone.classList.contains('camera-only')) return;
            if (!self.isProcessing && e.dataTransfer.files.length > 0) {
                self._setFile(side, e.dataTransfer.files[0]);
            }
        });

        // Remove button
        var removeBtn = Utils.$('.btn-remove', dropZone);
        if (removeBtn) {
            removeBtn.addEventListener('click', function (e) {
                e.stopPropagation();
                self._clearFile(side);
            });
        }

        // Camera buttons (may be multiple: one in content, one in camera-only)
        var cameraBtns = dropZone.querySelectorAll('.btn-camera');
        for (var i = 0; i < cameraBtns.length; i++) {
            cameraBtns[i].addEventListener('click', function (e) {
                e.stopPropagation();
                if (!self.isProcessing) {
                    Camera.open(side);
                }
            });
        }
    },

    _setFile: function (side, file) {
        var check = Utils.validateFile(file);
        if (!check.valid) {
            Utils.showToast(check.error, 'error');
            return;
        }

        if (side === 'front') {
            this.frontFile = file;
        } else {
            this.backFile = file;
        }

        // Show preview
        var dropZone = Utils.$('#drop-zone-' + side);
        var content = Utils.$('.drop-zone-content', dropZone);
        var preview = Utils.$('.drop-zone-preview', dropZone);
        var thumb = Utils.$('.preview-thumb', dropZone);
        var nameEl = Utils.$('.preview-name', dropZone);

        content.classList.add('hidden');
        var cameraOnly = Utils.$('.drop-zone-camera-only', dropZone);
        if (cameraOnly) cameraOnly.classList.add('hidden');
        preview.classList.remove('hidden');
        thumb.src = URL.createObjectURL(file);
        nameEl.textContent = file.name;

        this._updateProcessButton();
    },

    _clearFile: function (side) {
        if (side === 'front') {
            this.frontFile = null;
        } else {
            this.backFile = null;
        }

        var dropZone = Utils.$('#drop-zone-' + side);
        var content = Utils.$('.drop-zone-content', dropZone);
        var preview = Utils.$('.drop-zone-preview', dropZone);
        var thumb = Utils.$('.preview-thumb', dropZone);

        var cameraOnly = Utils.$('.drop-zone-camera-only', dropZone);
        var docType = Utils.$('#doc-type-select').value;
        if (side === 'front' && docType === 'product_serial' && cameraOnly) {
            content.classList.add('hidden');
            cameraOnly.classList.remove('hidden');
        } else {
            content.classList.remove('hidden');
            if (cameraOnly) cameraOnly.classList.add('hidden');
        }
        preview.classList.add('hidden');
        if (thumb.src) {
            URL.revokeObjectURL(thumb.src);
            thumb.src = '';
        }

        this._updateProcessButton();
    },

    _updateLayout: function () {
        var docType = Utils.$('#doc-type-select').value;
        var backGroup = Utils.$('#back-upload-group');
        var frontLabel = Utils.$('.upload-label');
        var isSerial = docType === 'product_serial';

        if (docType === 'sa_id_card') {
            backGroup.classList.remove('hidden');
        } else {
            backGroup.classList.add('hidden');
            this._clearFile('back');
        }
        if (frontLabel) {
            frontLabel.innerHTML = isSerial
                ? 'Product Image <span class="required">*</span>'
                : 'Front Image <span class="required">*</span>';
        }

        // Serial mode: camera-only for front drop zone
        var frontDropZone = Utils.$('#drop-zone-front');
        if (isSerial) {
            this._clearFile('front');
            frontDropZone.classList.add('camera-only');
        } else {
            var frontPreview = Utils.$('.drop-zone-preview', frontDropZone);
            if (frontPreview.classList.contains('hidden')) {
                Utils.$('.drop-zone-content', frontDropZone).classList.remove('hidden');
            }
            var frontCameraOnly = Utils.$('.drop-zone-camera-only', frontDropZone);
            if (frontCameraOnly) frontCameraOnly.classList.add('hidden');
            frontDropZone.classList.remove('camera-only');
        }
    },

    _updateProcessButton: function () {
        var btn = Utils.$('#btn-process');
        btn.disabled = !this.frontFile || this.isProcessing;
    },

    processDocument: function () {
        if (!this.frontFile || this.isProcessing) return;

        var self = this;
        var docType = Utils.$('#doc-type-select').value;
        this.isProcessing = true;
        this._updateProcessButton();
        Results.showLoading(this.frontFile);

        var startTime = performance.now();
        var isSerial = docType === 'product_serial';
        var apiCall = isSerial
            ? Api.scanSerial(this.frontFile)
            : Api.processDocument(this.frontFile, docType, this.backFile);

        apiCall
            .then(function (result) {
                var duration = performance.now() - startTime;
                if (isSerial) {
                    Results.renderSerial(result, self.frontFile);
                } else {
                    Results.render(result, self.frontFile);
                }
                History.add(History.buildEntry(result, self.frontFile, duration, null));
                Utils.showToast(isSerial ? 'Serial number processed' : 'Document processed successfully', 'success');
            })
            .catch(function (err) {
                var duration = performance.now() - startTime;
                Results.showError(err.message);
                History.add(History.buildEntry(null, self.frontFile, duration, err.message));

                if (err.status === 401) {
                    Utils.$('#api-key-input').classList.add('error');
                    Utils.showToast('Authentication failed. Check your API key.', 'error');
                } else if (err.status === 429) {
                    Utils.showToast('Rate limit exceeded. Wait a moment and try again.', 'warning');
                } else {
                    Utils.showToast(err.message, 'error');
                }
            })
            .finally(function () {
                self.isProcessing = false;
                self._updateProcessButton();
            });
    },
};