/**
 * YwxApp 文档中心前台脚本
 *
 * 提供：目录折叠、移动端抽屉、代码复制、右侧锚点滚动高亮、版本切换。
 * 纯原生实现，不依赖任何库。
 */
(function () {
    'use strict';

    document.addEventListener('DOMContentLoaded', function () {
        initTreeToggle();
        initMobileDrawer();
        initCodeCopy();
        initTocScrollSpy();
        initVersionSwitch();
        scrollActiveIntoView();
    });

    /**
     * 侧边目录展开与折叠
     */
    function initTreeToggle() {
        var tree = document.querySelector('.dc-tree');
        if (!tree) {
            return;
        }

        tree.addEventListener('click', function (e) {
            var toggle = e.target.closest('.dc-tree-toggle');
            var dirLink = e.target.closest('.dc-tree-link.is-dir');
            var trigger = toggle || dirLink;

            if (!trigger) {
                return;
            }

            var li = trigger.closest('li');
            if (li) {
                li.classList.toggle('is-open');
            }
        });
    }

    /**
     * 移动端侧边栏抽屉
     */
    function initMobileDrawer() {
        var btn = document.getElementById('dcMenuToggle');
        var sidebar = document.getElementById('dcSidebar');
        var mask = document.getElementById('dcMask');

        if (!btn || !sidebar) {
            return;
        }

        function close() {
            sidebar.classList.remove('is-open');
            if (mask) {
                mask.classList.remove('is-show');
            }
        }

        btn.addEventListener('click', function () {
            sidebar.classList.toggle('is-open');
            if (mask) {
                mask.classList.toggle('is-show', sidebar.classList.contains('is-open'));
            }
        });

        if (mask) {
            mask.addEventListener('click', close);
        }

        // 点击目录项后自动收起抽屉
        sidebar.addEventListener('click', function (e) {
            if (e.target.closest('a.dc-tree-link') && window.innerWidth <= 860) {
                close();
            }
        });

        window.addEventListener('resize', function () {
            if (window.innerWidth > 860) {
                close();
            }
        });
    }

    /**
     * 代码块复制按钮
     */
    function initCodeCopy() {
        var blocks = document.querySelectorAll('.dc-content pre');

        Array.prototype.forEach.call(blocks, function (pre) {
            var btn = document.createElement('button');
            btn.className = 'dc-copy-btn';
            btn.type = 'button';
            btn.textContent = '复制';

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

                copyText(text, function (ok) {
                    btn.textContent = ok ? '已复制' : '复制失败';
                    btn.classList.toggle('is-done', ok);
                    setTimeout(function () {
                        btn.textContent = '复制';
                        btn.classList.remove('is-done');
                    }, 1600);
                });
            });

            pre.appendChild(btn);
        });
    }

    /**
     * 复制文本到剪贴板，兼容不支持 Clipboard API 的环境
     *
     * @param {string}   text 待复制文本
     * @param {Function} cb   回调，参数为是否成功
     */
    function copyText(text, cb) {
        if (navigator.clipboard && window.isSecureContext) {
            navigator.clipboard.writeText(text).then(function () {
                cb(true);
            }).catch(function () {
                cb(fallbackCopy(text));
            });
            return;
        }
        cb(fallbackCopy(text));
    }

    /**
     * 兜底复制方案
     *
     * @param {string} text 待复制文本
     * @returns {boolean}
     */
    function fallbackCopy(text) {
        var ta = document.createElement('textarea');
        ta.value = text;
        ta.style.position = 'fixed';
        ta.style.opacity = '0';
        document.body.appendChild(ta);
        ta.select();

        var ok = false;
        try {
            ok = document.execCommand('copy');
        } catch (err) {
            ok = false;
        }

        document.body.removeChild(ta);
        return ok;
    }

    /**
     * 右侧锚点滚动高亮
     */
    function initTocScrollSpy() {
        var toc = document.getElementById('dcToc');
        var content = document.getElementById('dcContent');

        if (!toc || !content) {
            return;
        }

        var links = Array.prototype.slice.call(toc.querySelectorAll('a[data-anchor]'));
        if (!links.length) {
            return;
        }

        var headings = links.map(function (link) {
            return document.getElementById(link.getAttribute('data-anchor'));
        }).filter(Boolean);

        if (!headings.length) {
            return;
        }

        var offset = 90;
        var ticking = false;

        function update() {
            var current = 0;

            for (var i = 0; i < headings.length; i++) {
                if (headings[i].getBoundingClientRect().top <= offset) {
                    current = i;
                } else {
                    break;
                }
            }

            links.forEach(function (link, index) {
                link.classList.toggle('is-active', index === current);
            });

            ticking = false;
        }

        window.addEventListener('scroll', function () {
            if (!ticking) {
                window.requestAnimationFrame(update);
                ticking = true;
            }
        }, { passive: true });

        update();
    }

    /**
     * 版本切换：保持当前文档路径，仅替换版本段
     */
    function initVersionSwitch() {
        var select = document.getElementById('dcVersionSelect');
        if (!select) {
            return;
        }

        select.addEventListener('change', function () {
            var opt = select.options[select.selectedIndex];
            var isDefault = opt.getAttribute('data-default') === '1';

            // 地址形如 /docs/<项目>[/<版本>]/<文档>
            var parts = window.location.pathname.split('/').filter(Boolean);
            if (parts.length < 2) {
                return;
            }

            var project = parts[1];
            var docName = parts[parts.length - 1];

            // 只有项目段时说明还未进入具体文档
            if (parts.length === 2) {
                window.location.href = '/docs/' + project;
                return;
            }

            window.location.href = isDefault
                ? '/docs/' + project + '/' + docName
                : '/docs/' + project + '/' + select.value + '/' + docName;
        });
    }

    /**
     * 让当前选中的目录项进入可视区域
     */
    function scrollActiveIntoView() {
        var active = document.querySelector('.dc-tree-item.is-active');
        var sidebar = document.getElementById('dcSidebar');

        if (!active || !sidebar) {
            return;
        }

        var top = active.offsetTop - sidebar.clientHeight / 2;
        if (top > 0) {
            sidebar.scrollTop = top;
        }
    }
})();