'use strict';
/**
 * paste_view.js — Logic for the paste view page.
 * Depends on: crypto.js (PasteCrypto), app.js (copyToClipboard)
 *
 * Reads the site name from <meta name="site-name"> so no Jinja injection
 * is needed in this external file.
 */

let _decryptedPaste = null;

document.addEventListener('DOMContentLoaded', async () => {
    let rawPayload;
    try {
        const island = document.getElementById('encryptedPayload');
        if (!island) return; // Not a paste view page
        rawPayload = JSON.parse(island.textContent);
    } catch (e) {
        showError('Bad Data', 'Could not read the paste payload.');
        return;
    }

    // Detect format from the data itself.
    // Encrypted pastes: "base64url:base64url" string.
    // Plaintext pastes: a JSON object.
    const isEncrypted = typeof rawPayload === 'string' &&
        /^[A-Za-z0-9_-]+:[A-Za-z0-9_-]+$/.test(rawPayload);

    if (isEncrypted) {
        const keyBase64 = window.location.hash.slice(1);
        if (!keyBase64) {
            showError('No Key',
                'The decryption key is missing from the URL. ' +
                'Use the full link including the # part.');
            return;
        }
        try {
            const key       = await PasteCrypto.importKey(keyBase64);
            const plaintext = await PasteCrypto.decrypt(rawPayload, key);
            _decryptedPaste = JSON.parse(plaintext);
        } catch (e) {
            showError('Decryption Failed', 'Wrong key or tampered data.');
            return;
        }
    } else {
        // Plaintext paste — rawPayload is already the parsed JSON object.
        try {
            _decryptedPaste = (typeof rawPayload === 'object')
                ? rawPayload
                : JSON.parse(rawPayload);
        } catch (e) {
            showError('Bad Data', 'Could not parse paste data.');
            return;
        }
    }

    renderPaste(_decryptedPaste);
    initPasteActions();
    initLineNumbers();
});

function initPasteActions() {
    const rawBtn = document.getElementById('rawBtn');
    const copyBtn = document.getElementById('copyBtn');
    const downloadBtn = document.getElementById('downloadBtn');

    if (rawBtn)      rawBtn.addEventListener('click', rawView);
    if (copyBtn)     copyBtn.addEventListener('click', copyPaste);
    if (downloadBtn) downloadBtn.addEventListener('click', downloadPaste);
}

function initLineNumbers() {
    const toggle = document.getElementById('lineNoToggle');
    const viewPre = document.getElementById('viewPre');
    if (!toggle || !viewPre) return;

    // Load preference from localStorage (default to checked)
    const stored = localStorage.getItem('show_line_numbers');
    const isEnabled = (stored === null) ? true : (stored === 'true');
    toggle.checked = isEnabled;

    const updateLines = () => {
        const checked = toggle.checked;
        if (checked) {
            viewPre.classList.add('line-numbers');
        } else {
            viewPre.classList.remove('line-numbers');
        }
        localStorage.setItem('show_line_numbers', checked);

        // Re-highlight if a language is selected to force Prism to update the numbers span
        const code = document.getElementById('codeBlock');
        if (code && (code.className.includes('language-') || viewPre.className.includes('language-'))) {
            // Prism's line-numbers plugin needs to clean up if turning off
            if (!checked) {
                const existing = viewPre.querySelector('.line-numbers-rows');
                if (existing) existing.remove();
            }
            Prism.highlightElement(code);
        }
    };

    toggle.addEventListener('change', updateLines);

    // Initial state
    if (isEnabled) {
        viewPre.classList.add('line-numbers');
    }
}

function renderPaste(paste) {
    const siteName = document.querySelector('meta[name="site-name"]')?.content || '';
    const title    = paste.title || 'Untitled';
    document.title = title + (siteName ? ' \u2014 ' + siteName : '');
    document.getElementById('navPasteTitle').textContent = title;

    const lang        = paste.language || 'text';
    const prismLangMap = { text: false, html: 'markup', xml: 'markup', docker: 'docker' };
    const prismLang   = (lang in prismLangMap) ? prismLangMap[lang] : lang;

    const codeBlock = document.getElementById('codeBlock');
    const viewPre   = document.getElementById('viewPre');
    codeBlock.textContent = paste.content || '';
    if (prismLang) {
        codeBlock.className = 'language-' + prismLang;
        viewPre.className   = 'language-' + prismLang;
        Prism.highlightElement(codeBlock);
    }

    document.getElementById('viewFull').style.display = 'block';
}

function showError(title, detail) {
    document.getElementById('errorTitle').textContent   = title;
    document.getElementById('errorDetail').textContent  = detail;
    document.getElementById('errorState').style.display = 'block';
}

function rawView() {
    if (!_decryptedPaste) return;
    const blob = new Blob([_decryptedPaste.content], { type: 'text/plain; charset=utf-8' });
    const url  = URL.createObjectURL(blob);
    const a    = Object.assign(document.createElement('a'),
        { href: url, target: '_blank', rel: 'noopener noreferrer' });
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
    setTimeout(() => URL.revokeObjectURL(url), 10000);
}

async function copyPaste() {
    if (!_decryptedPaste) return;
    const ok  = await copyToClipboard(_decryptedPaste.content);
    const btn = document.getElementById('copyBtn');
    if (btn) {
        const t = btn.textContent;
        btn.textContent = ok ? 'Copied!' : 'Failed';
        setTimeout(() => btn.textContent = t, 1500);
    }
}

function downloadPaste() {
    if (!_decryptedPaste) return;
    const { title = 'untitled', content = '', language = 'text' } = _decryptedPaste;
    const extMap = {
        javascript: '.js',  typescript: '.ts',  python:  '.py',   java:       '.java',
        c:          '.c',   cpp:        '.cpp',  csharp:  '.cs',   html:       '.html',
        css:        '.css', scss:       '.scss', sql:     '.sql',  json:       '.json',
        yaml:       '.yaml',xml:        '.xml',  bash:    '.sh',   powershell: '.ps1',
        php:        '.php', ruby:       '.rb',   go:      '.go',   rust:       '.rs',
        swift:      '.swift',kotlin:    '.kt',   markdown:'.md',   diff:       '.diff',
        docker:     '',     nginx:      '.conf', toml:    '.toml', ini:        '.ini',
    };
    const filename = title.replace(/[^a-z0-9.\-]/gi, '_') + (extMap[language] ?? '.txt');
    const blob = new Blob([content], { type: 'text/plain' });
    const url  = URL.createObjectURL(blob);
    const a    = Object.assign(document.createElement('a'), { href: url, download: filename });
    document.body.appendChild(a);
    a.click();
    document.body.removeChild(a);
    URL.revokeObjectURL(url);
}