/**
 * UI Management Module
 * Handles DOM manipulation and view switching
 */

class UIManager {
    constructor() {
        this.currentFile = null;
        this.currentHistory = null;
        this.initializeElements();
    }

    initializeElements() {
        // Views
        this.welcomeView = document.getElementById('welcomeView');
        this.fileView = document.getElementById('fileView');
        this.historyView = document.getElementById('historyView');
        this.diffView = document.getElementById('diffView');

        // File view elements
        this.fileName = document.getElementById('fileName');
        this.filePath = document.getElementById('filePath');
        this.fileContent = document.getElementById('fileContent');
        this.historyBtn = document.getElementById('historyBtn');
        this.diffBtn = document.getElementById('diffBtn');

        // History view elements
        this.historyContent = document.getElementById('historyContent');
        this.backFromHistoryBtn = document.getElementById('backFromHistoryBtn');

        // Diff view elements
        this.rev1Select = document.getElementById('rev1Select');
        this.rev2Select = document.getElementById('rev2Select');
        this.generateDiffBtn = document.getElementById('generateDiffBtn');
        this.diffContent = document.getElementById('diffContent');
        this.backFromDiffBtn = document.getElementById('backFromDiffBtn');

        // Tree elements
        this.treeContainer = document.getElementById('treeContainer');
        this.refreshBtn = document.getElementById('refreshBtn');

        // Status
        this.status = document.getElementById('status');
    }

    /**
     * Show a specific view and hide others
     * @param {HTMLElement} view - View to show
     */
    showView(view) {
        [this.welcomeView, this.fileView, this.historyView, this.diffView].forEach(v => {
            if (v) v.classList.add('hidden');
        });
        if (view) view.classList.remove('hidden');
    }

    /**
     * Display file content
     * @param {string} path - File path
     * @param {string} content - File content
     */
    displayFile(path, content) {
        this.currentFile = path;
        this.fileName.textContent = path.split('/').pop();
        this.filePath.textContent = path;
        
        // Escape HTML and display content
        const escapedContent = this.escapeHtml(content);
        this.fileContent.innerHTML = `<pre><code>${escapedContent}</code></pre>`;
        
        this.showView(this.fileView);
    }

    /**
     * Display file history
     * @param {Array} history - Array of revision objects
     */
    displayHistory(history) {
        this.currentHistory = history;
        
        if (!history || history.length === 0) {
            this.historyContent.innerHTML = '<div class="loading">No history available</div>';
            this.showView(this.historyView);
            return;
        }

        const historyHTML = history.map(revision => `
            <div class="history-item" data-revision="${revision.revision}">
                <div class="history-item-header">
                    <span class="history-revision">${revision.revision}</span>
                    <span class="history-date">${revision.date || 'N/A'}</span>
                </div>
                <div class="history-author">Author: <strong>${revision.author || 'Unknown'}</strong></div>
                <span class="history-state">${revision.state || 'Exp'}</span>
                <div class="history-lines">${revision.lines_changed || 'N/A'}</div>
            </div>
        `).join('');

        this.historyContent.innerHTML = historyHTML;
        this.showView(this.historyView);

        // Add click handlers to history items
        this.historyContent.querySelectorAll('.history-item').forEach(item => {
            item.addEventListener('click', () => {
                const revision = item.dataset.revision;
                window.app.loadFileAtRevision(this.currentFile, revision);
            });
        });
    }

    /**
     * Display diff
     * @param {string} diffText - Diff content
     */
    displayDiff(diffText) {
        if (!diffText) {
            this.diffContent.innerHTML = '<div class="loading">No differences found</div>';
            this.showView(this.diffView);
            return;
        }

        // Parse and colorize diff
        const lines = diffText.split('\n');
        const colorizedLines = lines.map(line => {
            let className = '';
            if (line.startsWith('+++') || line.startsWith('---') || line.startsWith('@@')) {
                className = 'diff-line header';
            } else if (line.startsWith('+')) {
                className = 'diff-line added';
            } else if (line.startsWith('-')) {
                className = 'diff-line removed';
            } else {
                className = 'diff-line context';
            }
            const escapedLine = this.escapeHtml(line);
            return `<div class="${className}">${escapedLine}</div>`;
        }).join('');

        this.diffContent.innerHTML = `<pre><code>${colorizedLines}</code></pre>`;
        this.showView(this.diffView);
    }

    /**
     * Populate revision selectors
     * @param {Array} history - Array of revision objects
     */
    populateRevisionSelectors(history) {
        if (!history || history.length === 0) {
            this.rev1Select.innerHTML = '<option>No revisions available</option>';
            this.rev2Select.innerHTML = '<option>No revisions available</option>';
            return;
        }

        const options = history.map(rev => 
            `<option value="${rev.revision}">${rev.revision} - ${rev.date || 'N/A'}</option>`
        ).join('');

        this.rev1Select.innerHTML = options;
        this.rev2Select.innerHTML = options;

        // Set default selections
        if (history.length > 1) {
            this.rev1Select.selectedIndex = history.length - 1;
            this.rev2Select.selectedIndex = 0;
        }
    }

    /**
     * Update status indicator
     * @param {string} message - Status message
     * @param {string} type - Status type: 'connecting', 'connected', 'error'
     */
    updateStatus(message, type = 'connecting') {
        this.status.textContent = message;
        this.status.className = `status ${type}`;
    }

    /**
     * Show loading state
     * @param {string} message - Loading message
     */
    showLoading(message = 'Loading...') {
        this.fileContent.innerHTML = `<div class="loading">${message}</div>`;
    }

    /**
     * Show error message
     * @param {string} message - Error message
     */
    showError(message) {
        this.fileContent.innerHTML = `<div class="loading" style="color: #991b1b;">${this.escapeHtml(message)}</div>`;
    }

    /**
     * Escape HTML special characters
     * @param {string} text - Text to escape
     * @returns {string} Escaped text
     */
    escapeHtml(text) {
        const map = {
            '&': '&amp;',
            '<': '&lt;',
            '>': '&gt;',
            '"': '&quot;',
            "'": '&#039;'
        };
        return text.replace(/[&<>"']/g, m => map[m]);
    }

    /**
     * Build tree view from file list
     * @param {Array} files - Array of file paths
     * @param {Function} onFileClick - Callback when file is clicked
     */
    buildTree(files, onFileClick) {
        if (!files || files.length === 0) {
            this.treeContainer.innerHTML = '<div class="loading">No files found</div>';
            return;
        }

        // Build hierarchical tree structure
        const tree = {};
        files.forEach(file => {
            const parts = file.split('/');
            let current = tree;
            parts.forEach((part, index) => {
                if (!current[part]) {
                    current[part] = {};
                }
                current = current[part];
            });
        });

        // Render tree
        this.treeContainer.innerHTML = '';
        this.renderTreeNode(tree, '', this.treeContainer, onFileClick);
    }

    /**
     * Recursively render tree nodes
     * @param {object} node - Tree node
     * @param {string} path - Current path
     * @param {HTMLElement} container - Container element
     * @param {Function} onFileClick - Callback when file is clicked
     */
    renderTreeNode(node, path, container, onFileClick) {
        const keys = Object.keys(node).sort();
        
        keys.forEach(key => {
            const fullPath = path ? `${path}/${key}` : key;
            const isFile = Object.keys(node[key]).length === 0;
            
            const item = document.createElement('div');
            item.className = 'tree-item';
            
            const icon = document.createElement('span');
            icon.className = 'tree-item-icon';
            icon.textContent = isFile ? '📄' : '📁';
            
            const name = document.createElement('span');
            name.className = 'tree-item-name';
            name.textContent = key;
            
            item.appendChild(icon);
            item.appendChild(name);
            
            if (isFile) {
                item.addEventListener('click', () => {
                    // Remove active class from all items
                    container.querySelectorAll('.tree-item').forEach(i => i.classList.remove('active'));
                    item.classList.add('active');
                    onFileClick(fullPath);
                });
            }
            
            container.appendChild(item);
            
            // Recursively render subdirectories
            if (!isFile) {
                this.renderTreeNode(node[key], fullPath, container, onFileClick);
            }
        });
    }

    /**
     * Clear active selection in tree
     */
    clearTreeSelection() {
        this.treeContainer.querySelectorAll('.tree-item').forEach(item => {
            item.classList.remove('active');
        });
    }
}

// Create global UI manager instance
const ui = new UIManager();