import { PDFDocument, PDFName } from 'pdf-lib';
import { createIcons, icons } from 'lucide';

// State management
const pageState: { pdfDoc: PDFDocument | null; file: File | null } = {
    pdfDoc: null,
    file: null,
};

// UI helpers
function showLoader(message: string = 'Processing...') {
    const loader = document.getElementById('loader-modal');
    const loaderText = document.getElementById('loader-text');
    if (loader) loader.classList.remove('hidden');
    if (loaderText) loaderText.textContent = message;
}

function hideLoader() {
    const loader = document.getElementById('loader-modal');
    if (loader) loader.classList.add('hidden');
}

function showAlert(title: string, message: string, type: string = 'error', callback?: () => void) {
    const modal = document.getElementById('alert-modal');
    const alertTitle = document.getElementById('alert-title');
    const alertMessage = document.getElementById('alert-message');
    const okBtn = document.getElementById('alert-ok');

    if (alertTitle) alertTitle.textContent = title;
    if (alertMessage) alertMessage.textContent = message;
    if (modal) modal.classList.remove('hidden');

    if (okBtn) {
        const newOkBtn = okBtn.cloneNode(true) as HTMLElement;
        okBtn.replaceWith(newOkBtn);
        newOkBtn.addEventListener('click', () => {
            modal?.classList.add('hidden');
            if (callback) callback();
        });
    }
}

function downloadFile(blob: Blob, filename: string) {
    const url = URL.createObjectURL(blob);
    const a = document.createElement('a');
    a.href = url;
    a.download = filename;
    a.click();
    URL.revokeObjectURL(url);
}

function updateFileDisplay() {
    const displayArea = document.getElementById('file-display-area');
    if (!displayArea || !pageState.file || !pageState.pdfDoc) return;

    const fileSize = pageState.file.size < 1024 * 1024
        ? `${(pageState.file.size / 1024).toFixed(1)} KB`
        : `${(pageState.file.size / 1024 / 1024).toFixed(2)} MB`;
    const pageCount = pageState.pdfDoc.getPageCount();

    displayArea.innerHTML = `
        <div class="bg-gray-700 p-3 rounded-lg border border-gray-600 hover:border-indigo-500 transition-colors">
            <div class="flex items-center justify-between">
                <div class="flex-1 min-w-0">
                    <p class="truncate font-medium text-white">${pageState.file.name}</p>
                    <p class="text-gray-400 text-sm">${fileSize} • ${pageCount} page${pageCount !== 1 ? 's' : ''}</p>
                </div>
                <button id="remove-file" class="text-red-400 hover:text-red-300 p-2 flex-shrink-0 ml-2" title="Remove file">
                    <i data-lucide="trash-2" class="w-4 h-4"></i>
                </button>
            </div>
        </div>
    `;

    createIcons({ icons });

    document.getElementById('remove-file')?.addEventListener('click', () => resetState());
}

function resetState() {
    pageState.pdfDoc = null;
    pageState.file = null;
    const displayArea = document.getElementById('file-display-area');
    if (displayArea) displayArea.innerHTML = '';
    document.getElementById('options-panel')?.classList.add('hidden');
    const fileInput = document.getElementById('file-input') as HTMLInputElement;
    if (fileInput) fileInput.value = '';
}

// File handling
async function handleFileUpload(file: File) {
    if (!file || file.type !== 'application/pdf') {
        showAlert('Error', 'Please upload a valid PDF file.');
        return;
    }

    showLoader('Loading PDF...');
    try {
        const arrayBuffer = await file.arrayBuffer();
        pageState.pdfDoc = await PDFDocument.load(arrayBuffer);
        pageState.file = file;
        updateFileDisplay();
        document.getElementById('options-panel')?.classList.remove('hidden');
    } catch (error) {
        console.error(error);
        showAlert('Error', 'Failed to load PDF file.');
    } finally {
        hideLoader();
    }
}

// Process function
async function processRemoveAnnotations() {
    if (!pageState.pdfDoc) {
        showAlert('Error', 'Please upload a PDF file first.');
        return;
    }

    showLoader('Removing annotations...');
    try {
        const pages = pageState.pdfDoc.getPages();

        // Remove all annotations from all pages
        for (let i = 0; i < pages.length; i++) {
            const page = pages[i];
            const annotRefs = page.node.Annots()?.asArray() || [];
            if (annotRefs.length > 0) {
                page.node.delete(PDFName.of('Annots'));
            }
        }

        const newPdfBytes = await pageState.pdfDoc.save();
        downloadFile(new Blob([new Uint8Array(newPdfBytes)], { type: 'application/pdf' }), 'annotations-removed.pdf');
        showAlert('Success', 'Annotations removed successfully!', 'success', () => { resetState(); });
    } catch (e) {
        console.error(e);
        showAlert('Error', 'Could not remove annotations.');
    } finally {
        hideLoader();
    }
}

// Initialize
document.addEventListener('DOMContentLoaded', () => {
    const fileInput = document.getElementById('file-input') as HTMLInputElement;
    const dropZone = document.getElementById('drop-zone');
    const processBtn = document.getElementById('process-btn');
    const backBtn = document.getElementById('back-to-tools');

    fileInput?.addEventListener('change', (e) => {
        const file = (e.target as HTMLInputElement).files?.[0];
        if (file) handleFileUpload(file);
    });

    dropZone?.addEventListener('dragover', (e) => {
        e.preventDefault();
        dropZone.classList.add('border-indigo-500');
    });

    dropZone?.addEventListener('dragleave', () => {
        dropZone.classList.remove('border-indigo-500');
    });

    dropZone?.addEventListener('drop', (e) => {
        e.preventDefault();
        dropZone.classList.remove('border-indigo-500');
        const file = e.dataTransfer?.files[0];
        if (file) handleFileUpload(file);
    });

    processBtn?.addEventListener('click', processRemoveAnnotations);

    backBtn?.addEventListener('click', () => {
        window.location.href = '../../index.html';
    });
});