import { ScriptLoader } from './script-loader.js';
import { ViewerApi } from './viewer-api.js';
import { ViewerProgressBar } from './viewer-progress-bar.js';

export class FileViewer {
    constructor() {
        const params = new URLSearchParams(window.location.search);
        this.id = params.get('id');
        this.name = params.get('name') || 'Dokumen';
        this.type = (params.get('type') || 'pdf').toLowerCase();

        this.titleEl = document.getElementById('viewer-title');
        this.typeBadgeEl = document.getElementById('viewer-type');
        this.downloadEl = document.getElementById('viewer-download');
        this.contentEl = document.getElementById('viewer-content');

        this.assetUrl = this.id ? ViewerApi.assetUrl(this.id) : null;
    }

    async init() {
        if (!this.id) {
            this._renderError('Parameter berkas tidak ditemukan di URL.');
            return;
        }

        document.title = `${this.name} — Pratinjau Dokumen`;
        this.titleEl.textContent = this.name;
        this.typeBadgeEl.textContent = this.type.toUpperCase();
        this._setupDownload();

        try {
            if (this.type === 'docx') {
                await this._renderDocx();
            } else {
                this._renderPdf();
            }
        } catch (err) {
            console.error(err);
            this._renderError('Gagal memuat pratinjau berkas. Silakan unduh berkas untuk membuka secara lokal.');
        }
    }

    _setupDownload() {
        const ext = `.${this.type}`;
        const filename = this.name.toLowerCase().endsWith(ext) ? this.name : `${this.name}${ext}`;

        this.downloadEl.removeAttribute('href');
        this.downloadEl.style.cursor = 'pointer';
        this.downloadEl.addEventListener('click', async event => {
            event.preventDefault();
            const originalHtml = this.downloadEl.innerHTML;
            this.downloadEl.innerHTML = '<i class="fas fa-spinner fa-spin"></i> Mengunduh…';
            this.downloadEl.style.pointerEvents = 'none';
            try {
                const blob = await ViewerApi.fetchBlob(this.assetUrl);
                const blobUrl = URL.createObjectURL(blob);
                const link = document.createElement('a');
                link.style.display = 'none';
                link.href = blobUrl;
                link.download = filename;
                document.body.appendChild(link);
                link.click();
                document.body.removeChild(link);
                URL.revokeObjectURL(blobUrl);
            } catch (err) {
                console.warn('Blob download failed, falling back:', err);
                window.open(`${this.assetUrl}?download`, '_blank');
            } finally {
                this.downloadEl.innerHTML = originalHtml;
                this.downloadEl.style.pointerEvents = '';
            }
        });
    }

    _renderPdf() {
        const iframe = document.createElement('iframe');
        iframe.className = 'viewer-pdf-frame';
        iframe.title = this.name;
        iframe.src = this.assetUrl;
        this.contentEl.replaceChildren(iframe);
    }

    async _renderDocx() {
        const progressBar = new ViewerProgressBar(this.contentEl);
        const [blob] = await Promise.all([
            ViewerApi.fetchBlob(this.assetUrl, ratio => progressBar.update(ratio)),
            this._loadDocxLibraries(),
        ]);
        progressBar.finish();

        if (!window.docx || typeof window.docx.renderAsync !== 'function') {
            throw new Error('Library docx-preview belum dimuat.');
        }

        const container = document.createElement('div');
        container.className = 'viewer-docx-content';
        this.contentEl.replaceChildren(container);

        await window.docx.renderAsync(blob, container, null, {
            inWrapper: true,
            ignoreWidth: false,
            ignoreHeight: false,
        });
    }

    async _loadDocxLibraries() {
        if (window.docx) return;
        await ScriptLoader.load('https://unpkg.com/jszip@3.10.1/dist/jszip.min.js');
        await ScriptLoader.load('https://unpkg.com/docx-preview@0.3.5/dist/docx-preview.js');
    }

    _renderError(message) {
        const wrapper = document.createElement('div');
        wrapper.className = 'viewer-error';

        const icon = document.createElement('i');
        icon.className = 'fas fa-exclamation-triangle';

        const span = document.createElement('span');
        span.textContent = message;

        const back = document.createElement('a');
        back.href = 'index.html#repository';
        back.className = 'btn-back-mini';
        back.textContent = 'Kembali ke Repositori';

        wrapper.append(icon, span, back);
        this.contentEl.replaceChildren(wrapper);
    }
}