blog/themes/Ying/assets/js/modules/utils.js

function themeSweep(newTheme, callback) {
    // View Transition API — browser-native crossfade, zero JS animation overhead.
    // Same principle as image lightbox transitions. Chrome/Edge 111+, Opera 97+.
    if (document.startViewTransition) {
        document.startViewTransition(function() { callback(); });
        return;
    }

    // Fallback: lightweight overlay for Safari / Firefox
    var oldTheme = document.documentElement.getAttribute('data-theme');
    var tint = oldTheme === 'dark'
        ? 'rgba(15,23,42,0.95)'
        : 'rgba(255,255,255,0.95)';

    var overlay = document.createElement('div');
    overlay.style.cssText =
        'position:fixed;inset:0;z-index:9999;pointer-events:none;' +
        'background:' + tint + ';opacity:1;' +
        'transition:opacity 0.22s ease;' +
        'will-change:opacity;contain:paint;';
    document.body.appendChild(overlay);

    var cleaned = false;
    function cleanup() {
        if (cleaned) return;
        cleaned = true;
        if (overlay.parentNode) overlay.parentNode.removeChild(overlay);
    }

    callback();
    overlay.offsetWidth;
    overlay.style.opacity = '0';

    overlay.addEventListener('transitionend', function(e) {
        if (e.propertyName !== 'opacity') return;
        cleanup();
    });
    setTimeout(cleanup, 380);
}

// Toast Message Helper
window.showToast = function(text, type) {
    if (window.Toast) {
        var t = type || 'info';
        if (typeof window.Toast[t] === 'function') {
            window.Toast[t](text);
        } else {
            window.Toast.info(text);
        }
    }
};

// Theme Toggle Logic
window.initThemeToggle = function() {
    var avatar = document.getElementById('theme-toggle-avatar');
    if (!avatar) return;

    var newAvatar = avatar.cloneNode(true);
    avatar.parentNode.replaceChild(newAvatar, avatar);

    newAvatar.addEventListener('click', function(e) {
        e.preventDefault();

        var html = document.documentElement;
        var currentTheme = html.getAttribute('data-theme');
        var newTheme = currentTheme === 'dark' ? 'light' : 'dark';

        var apply = function() {
            html.setAttribute('data-theme', newTheme);
            localStorage.setItem('theme', newTheme);
            window.showToast('已切换至 ' + (newTheme === 'dark' ? '深色' : '浅色') + '模式', 'success');
            if (window.artalk && typeof window.artalk.setDarkMode === 'function') {
                window.artalk.setDarkMode(newTheme === 'dark');
            }
            window.dispatchEvent(new Event('resize'));
        };

        themeSweep(newTheme, apply);
    });
};

// Code Folding Logic
window.initCodeFold = function() {
    var codeBlocks = document.querySelectorAll('.highlight');
    codeBlocks.forEach(function(block) {
        if (block.parentNode && block.parentNode.classList.contains('code-fold-container')) return;

        var pre = block.querySelector('pre');
        if (!pre) return;

        // Use pre's content height; 0 means layout not ready, wrap conservatively
        var contentHeight = pre.scrollHeight || block.scrollHeight;
        if (contentHeight && contentHeight <= 360) return;

        var wrapper = document.createElement('div');
        wrapper.className = 'code-fold-container collapsed';
        block.parentNode.insertBefore(wrapper, block);
        wrapper.appendChild(block);

        var btn = document.createElement('button');
        btn.type = 'button';
        btn.className = 'code-expand-btn';
        wrapper.appendChild(btn);

        var syncButton = function() {
            var collapsed = wrapper.classList.contains('collapsed');
            btn.innerHTML = collapsed
                ? '<span><i class="ri-arrow-down-s-line" style="margin-right:4px;"></i> 展开代码 </span>'
                : '<span><i class="ri-arrow-up-s-line" style="margin-right:4px;"></i> 收起代码 </span>';
        };

        btn.onclick = function() {
            wrapper.classList.toggle('collapsed');
            syncButton();
        };
        syncButton();
    });
};

// Code Copy Logic
window.initCodeCopy = function() {
    var codeBlocks = document.querySelectorAll('pre');

    codeBlocks.forEach(function(pre) {
        if (pre.parentNode.querySelector('.copy-code-btn')) return;
        if (pre.querySelector('.copy-code-btn')) return;

        var btn = document.createElement('button');
        btn.className = 'copy-code-btn';
        btn.innerHTML = '<i class="ri-file-copy-line"></i>';
        btn.title = "复制代码";
        btn.style.cssText =
            'position:absolute;top:-6px;right:5px;background:transparent;border:none;' +
            'color:#888;cursor:pointer;padding:5px;border-radius:4px;' +
            'transition:all 0.2s;opacity:0;z-index:10;';

        pre.addEventListener('mouseenter', function() { btn.style.opacity = '1'; });
        pre.addEventListener('mouseleave', function() { btn.style.opacity = '0'; });

        if (window.isMobile()) { btn.style.opacity = '1'; }

        btn.addEventListener('click', function(e) {
            e.stopPropagation();
            var code = pre.querySelector('code') ? pre.querySelector('code').innerText : pre.innerText;

            if (navigator.clipboard) {
                navigator.clipboard.writeText(code).then(function() {
                    window.showToast('代码已复制 / Copied!', 'success');
                    btn.innerHTML = '<i class="ri-check-line"></i>';
                    setTimeout(function() { btn.innerHTML = '<i class="ri-file-copy-line"></i>'; }, 2000);
                }).catch(function() {
                    window.showToast('复制失败 / Failed', 'error');
                });
            } else {
                var textarea = document.createElement('textarea');
                textarea.value = code;
                document.body.appendChild(textarea);
                textarea.select();
                document.execCommand('copy');
                document.body.removeChild(textarea);
                window.showToast('代码已复制 / Copied!', 'success');
            }
        });

        if (getComputedStyle(pre).position === 'static') {
            pre.style.position = 'relative';
        }

        pre.appendChild(btn);
    });
};