// Diff Viewer using diff2html with file tree sidebar
const DiffViewer = {
    init(containerId, options = {}) {
        this.container = document.getElementById(containerId);
        this.options = options;
        this.rawDiff = null;
        this.currentMode = 'side-by-side';
        this.files = []; // parsed file info for tree
        this.observer = null; // scroll observer for highlight sync

        if (!this.container) {
            console.error('Diff container not found:', containerId);
            return;
        }
    },

    // Parse unified diff string to extract per-file info
    _parseDiffFiles(diffString) {
        if (!diffString) return [];
        const files = [];
        const fileRegex = /^diff --git a\/(.*?) b\/(.*?)$/gm;
        let match;
        const positions = [];

        while ((match = fileRegex.exec(diffString)) !== null) {
            positions.push({ name: match[2] || match[1], index: match.index });
        }

        for (let i = 0; i < positions.length; i++) {
            const start = positions[i].index;
            const end = i + 1 < positions.length ? positions[i + 1].index : diffString.length;
            const chunk = diffString.substring(start, end);

            // Count additions and deletions
            let additions = 0, deletions = 0;
            const lines = chunk.split('\n');
            for (const line of lines) {
                if (line.startsWith('+') && !line.startsWith('+++')) additions++;
                if (line.startsWith('-') && !line.startsWith('---')) deletions++;
            }

            // Determine change type
            let changeType = 'modified';
            if (chunk.includes('new file mode')) changeType = 'added';
            else if (chunk.includes('deleted file mode')) changeType = 'deleted';
            else if (chunk.includes('rename from')) changeType = 'renamed';

            files.push({
                name: positions[i].name,
                path: positions[i].name,
                additions,
                deletions,
                changeType,
            });
        }

        return files;
    },

    // Build tree structure from flat file list
    _buildTree(files) {
        const root = { name: '', path: '', children: [], isDir: true };

        files.forEach(file => {
            const parts = file.path.split('/');
            let current = root;

            for (let i = 0; i < parts.length; i++) {
                const part = parts[i];
                const isFile = i === parts.length - 1;

                if (isFile) {
                    current.children.push({
                        ...file,
                        name: part,
                        isDir: false,
                    });
                } else {
                    let child = current.children.find(c => c.isDir && c.name === part);
                    if (!child) {
                        child = {
                            name: part,
                            path: parts.slice(0, i + 1).join('/'),
                            children: [],
                            isDir: true,
                        };
                        current.children.push(child);
                    }
                    current = child;
                }
            }
        });

        // Sort: directories first, then files, alphabetically
        const sortTree = (node) => {
            if (node.children) {
                node.children.sort((a, b) => {
                    if (a.isDir && !b.isDir) return -1;
                    if (!a.isDir && b.isDir) return 1;
                    return a.name.localeCompare(b.name);
                });
                node.children.forEach(sortTree);
            }
        };
        sortTree(root);

        return root;
    },

    // Render file tree sidebar HTML
    _renderFileTree(tree) {
        const totalFiles = this.files.length;
        const totalAdd = this.files.reduce((s, f) => s + f.additions, 0);
        const totalDel = this.files.reduce((s, f) => s + f.deletions, 0);

        let html = `
            <div class="file-tree-header">
                <div class="file-tree-stats">
                    <span class="text-sm font-medium text-gray-700">${totalFiles} 文件</span>
                    <span class="text-xs text-green-600">+${totalAdd}</span>
                    <span class="text-xs text-red-600">-${totalDel}</span>
                </div>
            </div>
            <div class="file-tree-list">`;

        html += this._renderTreeNode(tree, 0);
        html += '</div>';

        return html;
    },

    _renderTreeNode(node, depth) {
        let html = '';

        if (node.isDir) {
            // Only render directory label if not root
            if (depth > 0) {
                html += `<div class="file-tree-dir" style="padding-left:${depth * 16}px" data-path="${node.path}">
                    <span class="file-tree-toggle">▶</span>
                    <span class="file-tree-dirname">${node.name}/</span>
                </div>`;
            }
            // Render children
            const childDepth = depth > 0 ? depth + 1 : depth;
            if (node.children) {
                node.children.forEach(child => {
                    if (child.isDir) {
                        html += this._renderTreeNode(child, childDepth);
                    } else {
                        html += this._renderTreeNode(child, childDepth);
                    }
                });
            }
        } else {
            // File node
            const icon = this._getFileIcon(node.changeType);
            html += `<div class="file-tree-file" style="padding-left:${(depth + 1) * 16}px"
                         data-filename="${node.path}" title="${node.path}">
                <span class="file-tree-icon">${icon}</span>
                <span class="file-tree-name">${node.name}</span>
                <span class="file-tree-stats-inline">
                    <span class="text-green-600">+${node.additions}</span>
                    <span class="text-red-600">-${node.deletions}</span>
                </span>
            </div>`;
        }

        return html;
    },

    _getFileIcon(changeType) {
        switch (changeType) {
            case 'added': return '<span class="text-green-500">A</span>';
            case 'deleted': return '<span class="text-red-500">D</span>';
            case 'renamed': return '<span class="text-yellow-500">R</span>';
            default: return '<span class="text-gray-400">M</span>';
        }
    },

    // Render diff with file tree sidebar
    renderDiff(diffString, options = {}) {
        if (!this.container) return;

        // Store raw diff for view mode switching
        this.rawDiff = diffString;

        // Parse files for tree
        this.files = this._parseDiffFiles(diffString);
        const tree = this._buildTree(this.files);

        const config = {
            drawFileList: false, // We use our own file tree
            fileListToggle: false,
            fileContentToggle: true,
            matching: options.matching || 'lines',
            outputFormat: options.outputFormat || this.currentMode === 'unified' ? 'line-by-line' : 'side-by-side',
            synchronisedScroll: true,
            highlight: true,
            renderNothingWhenEmpty: false,
        };

        this.currentMode = config.outputFormat === 'line-by-line' ? 'unified' : 'side-by-side';

        // Build layout: sidebar + diff area
        const diffHtml = Diff2Html.html(diffString, config);
        const treeHtml = this._renderFileTree(tree);

        this.container.innerHTML = `
            <div class="diff-layout">
                <div class="diff-sidebar" id="diff-file-tree">
                    ${treeHtml}
                </div>
                <div class="diff-main" id="diff-content">
                    ${diffHtml}
                </div>
            </div>`;

        // Add syntax highlighting
        this.container.querySelectorAll('pre code').forEach(block => {
            if (window.hljs) {
                hljs.highlightElement(block);
            }
        });

        // Add data-filename attributes to file wrappers for scroll sync
        this._annotateFileSections();

        // Bind file tree click events
        this._bindFileTreeEvents();

        // Set up scroll spy
        this._setupScrollSpy();
    },

    // Render per-file diffs
    renderFiles(files, options = {}) {
        if (!this.container) return;

        if (!files || files.length === 0) {
            this.container.innerHTML = '<div class="text-gray-500 p-4">No changes</div>';
            return;
        }

        // Store files for tree
        this.files = files.map(f => {
            let additions = 0, deletions = 0;
            const lines = (f.patch || '').split('\n');
            for (const line of lines) {
                if (line.startsWith('+') && !line.startsWith('+++')) additions++;
                if (line.startsWith('-') && !line.startsWith('---')) deletions++;
            }
            return {
                name: f.filename,
                path: f.filename,
                additions,
                deletions,
                changeType: 'modified',
            };
        });

        const combinedDiff = files.map(f => f.patch).join('\n');
        this.rawDiff = combinedDiff;

        const tree = this._buildTree(this.files);
        const config = {
            drawFileList: false,
            fileListToggle: false,
            fileContentToggle: true,
            matching: options.matching || 'lines',
            outputFormat: options.outputFormat || (this.currentMode === 'unified' ? 'line-by-line' : 'side-by-side'),
            synchronisedScroll: true,
            highlight: true,
            renderNothingWhenEmpty: false,
        };

        const diffHtml = Diff2Html.html(combinedDiff, config);
        const treeHtml = this._renderFileTree(tree);

        this.container.innerHTML = `
            <div class="diff-layout">
                <div class="diff-sidebar" id="diff-file-tree">
                    ${treeHtml}
                </div>
                <div class="diff-main" id="diff-content">
                    ${diffHtml}
                </div>
            </div>`;

        this.container.querySelectorAll('pre code').forEach(block => {
            if (window.hljs) {
                hljs.highlightElement(block);
            }
        });

        this._annotateFileSections();
        this._bindFileTreeEvents();
        this._setupScrollSpy();
    },

    // Annotate diff2html file wrappers with data-filename
    _annotateFileSections() {
        const fileWrappers = this.container.querySelectorAll('.d2h-file-wrapper');
        fileWrappers.forEach(wrapper => {
            const header = wrapper.querySelector('.d2h-file-name');
            if (header) {
                const name = header.textContent.trim();
                // Extract just the filename from the header (diff2html adds a prefix)
                const cleanName = name.replace(/^\s*(Modified|Added|Deleted|Rename)\s*/i, '').trim();
                wrapper.setAttribute('data-filename', cleanName);
            }
        });
    },

    // Bind click events on file tree items
    _bindFileTreeEvents() {
        const treeItems = this.container.querySelectorAll('.file-tree-file');
        treeItems.forEach(item => {
            item.addEventListener('click', (e) => {
                const filename = item.getAttribute('data-filename');
                this.scrollToFile(filename);

                // Highlight active file in tree
                this.container.querySelectorAll('.file-tree-file').forEach(fi => fi.classList.remove('active'));
                item.classList.add('active');
            });
        });

        // Directory toggle
        const dirItems = this.container.querySelectorAll('.file-tree-dir');
        dirItems.forEach(dir => {
            dir.addEventListener('click', (e) => {
                const toggle = dir.querySelector('.file-tree-toggle');
                const path = dir.getAttribute('data-path');
                const isExpanded = toggle.textContent === '▼';

                toggle.textContent = isExpanded ? '▶' : '▼';

                // Toggle children visibility
                let sibling = dir.nextElementSibling;
                while (sibling) {
                    // Check if this sibling is still a child (starts with same path or is a file at same level)
                    const sibPath = sibling.getAttribute('data-path') || sibling.getAttribute('data-filename') || '';
                    if (!sibPath.startsWith(path + '/') && sibling.classList.contains('file-tree-dir')) {
                        break;
                    }
                    sibling.style.display = isExpanded ? 'none' : '';
                    sibling = sibling.nextElementSibling;
                }
            });
        });
    },

    // Scroll to a specific file section in the diff
    scrollToFile(filename) {
        const diffContent = this.container.querySelector('#diff-content');
        if (!diffContent) return;

        const fileWrappers = diffContent.querySelectorAll('.d2h-file-wrapper');
        for (const wrapper of fileWrappers) {
            const wrapperName = wrapper.getAttribute('data-filename');
            if (wrapperName && (wrapperName === filename || wrapperName.endsWith('/' + filename) || filename.endsWith('/' + wrapperName))) {
                wrapper.scrollIntoView({ behavior: 'smooth', block: 'start' });
                // Brief highlight effect
                wrapper.style.outline = '2px solid #3b82f6';
                setTimeout(() => { wrapper.style.outline = ''; }, 2000);
                return;
            }
        }
    },

    // Set up scroll spy to highlight current file in tree
    _setupScrollSpy() {
        const diffContent = this.container.querySelector('#diff-content');
        if (!diffContent) return;

        // Clean up old observer
        if (this.observer) {
            this.observer.disconnect();
        }

        const fileWrappers = diffContent.querySelectorAll('.d2h-file-wrapper');
        if (fileWrappers.length === 0) return;

        this.observer = new IntersectionObserver((entries) => {
            entries.forEach(entry => {
                if (entry.isIntersecting) {
                    const filename = entry.target.getAttribute('data-filename');
                    if (filename) {
                        // Highlight in tree
                        this.container.querySelectorAll('.file-tree-file').forEach(item => {
                            const treeName = item.getAttribute('data-filename');
                            if (treeName && (treeName === filename || treeName.endsWith('/' + filename) || filename.endsWith('/' + treeName))) {
                                item.classList.add('active');
                                // Scroll tree item into view if needed
                                item.scrollIntoView({ behavior: 'smooth', block: 'nearest' });
                            } else {
                                item.classList.remove('active');
                            }
                        });
                    }
                }
            });
        }, {
            root: diffContent,
            rootMargin: '-10% 0px -80% 0px',
            threshold: 0,
        });

        fileWrappers.forEach(wrapper => {
            this.observer.observe(wrapper);
        });
    },

    // Load and render diff from API
    async loadDiff(repoId, base, head, options = {}) {
        if (!this.container) return;

        this.container.innerHTML = '<div class="text-center p-8"><div class="spinner inline-block"></div><p class="mt-2 text-gray-500">Loading diff...</p></div>';

        try {
            const url = `/api/repos/${repoId}/diff?base=${encodeURIComponent(base)}&head=${encodeURIComponent(head)}`;
            const resp = await fetch(url);
            if (!resp.ok) throw new Error('Failed to load diff');

            const data = await resp.json();

            if (data.diff) {
                this.renderDiff(data.diff, options);
            } else if (Array.isArray(data)) {
                this.renderFiles(data, options);
            }
        } catch (err) {
            this.container.innerHTML = `<div class="text-red-500 p-4">Error loading diff: ${err.message}</div>`;
        }
    },

    // Load per-file diffs
    async loadFiles(repoId, base, head) {
        if (!this.container) return;

        this.container.innerHTML = '<div class="text-center p-8"><div class="spinner inline-block"></div><p class="text-gray-500">Loading files...</p></div>';

        try {
            const url = `/api/repos/${repoId}/diff?base=${encodeURIComponent(base)}&head=${encodeURIComponent(head)}&per_file=true`;
            const resp = await fetch(url);
            if (!resp.ok) throw new Error('Failed to load diff');

            const files = await resp.json();
            this.renderFiles(files);
        } catch (err) {
            this.container.innerHTML = `<div class="text-red-500 p-4">Error: ${err.message}</div>`;
        }
    },

    // Switch view mode (side-by-side or line-by-line)
    setViewMode(mode) {
        if (!this.container || !this.rawDiff) return;
        this.currentMode = mode;
        this.renderDiff(this.rawDiff, { outputFormat: mode === 'unified' ? 'line-by-line' : 'side-by-side' });
    },

    // Toggle file list visibility
    toggleFileList() {
        const sidebar = this.container.querySelector('.diff-sidebar');
        if (sidebar) {
            sidebar.style.display = sidebar.style.display === 'none' ? '' : 'none';
        }
    },

    // Expand/collapse all files
    toggleAllFiles(expand) {
        const fileContents = this.container.querySelectorAll('.d2h-file-wrapper');
        fileContents.forEach(file => {
            const content = file.querySelector('.d2h-file-diff');
            if (content) {
                content.style.display = expand ? 'block' : 'none';
            }
        });
    },

    // Insert a review suggestion inline at a specific line
    insertSuggestion(filename, line, side, severity, content, suggestionId) {
        const diffContent = this.container.querySelector('#diff-content');
        if (!diffContent) return;

        // Find the target file wrapper
        const fileWrappers = diffContent.querySelectorAll('.d2h-file-wrapper');
        let targetWrapper = null;
        for (const wrapper of fileWrappers) {
            const wrapperName = wrapper.getAttribute('data-filename');
            if (wrapperName && (wrapperName === filename || wrapperName.endsWith('/' + filename) || filename.endsWith('/' + wrapperName))) {
                targetWrapper = wrapper;
                break;
            }
        }
        if (!targetWrapper) return;

        // Find the target line
        const table = targetWrapper.querySelector('.d2h-diff-table');
        if (!table) return;

        const rows = table.querySelectorAll('tr');
        for (const row of rows) {
            // diff2html uses data-line-number on td elements
            const lineNumCell = side === 'left'
                ? row.querySelector('.d2h-code-linenumber .d2h-code-side-linenumber')
                : row.querySelector('.d2h-code-linenumber:not(.d2h-code-side-linenumber)');

            if (!lineNumCell) continue;

            const lineText = lineNumCell.textContent.trim();
            const lineNum = parseInt(lineText);
            if (lineNum === line) {
                // Create suggestion card
                const severityStyles = {
                    critical: 'border-l-4 border-red-500 bg-red-50',
                    warning: 'border-l-4 border-yellow-500 bg-yellow-50',
                    info: 'border-l-4 border-green-500 bg-green-50',
                };
                const severityLabels = {
                    critical: '🔴 严重',
                    warning: '🟡 建议',
                    info: '🟢 提示',
                };

                const suggestionRow = document.createElement('tr');
                suggestionRow.className = 'review-suggestion-row';
                suggestionRow.setAttribute('data-suggestion-id', suggestionId || '');
                suggestionRow.innerHTML = `
                    <td colspan="3" class="p-0">
                        <div class="review-suggestion-card ${severityStyles[severity] || severityStyles.info} p-3 mx-2 my-1 rounded">
                            <div class="flex items-center gap-2 mb-1">
                                <span class="text-xs font-medium">${severityLabels[severity] || severityLabels.info}</span>
                            </div>
                            <p class="text-sm text-gray-700">${content}</p>
                            <div class="mt-2 note-editor-placeholder" data-scope="suggestion" data-scope-key="${suggestionId || ''}"></div>
                        </div>
                    </td>`;

                // Insert after the current row
                row.parentNode.insertBefore(suggestionRow, row.nextSibling);
                return;
            }
        }
    }
};

// Export for use
window.DiffViewer = DiffViewer;