astralis/examples/DocumentBuilderTemplate.vala

using Astralis;
using Invercargill;
using Invercargill.DataStructures;
using Inversion;

/**
 * DocumentBuilderTemplate Example
 * 
 * Demonstrates loading an existing HTML template and modifying elements
 * using the DocumentModel classes. Shows how to:
 *   - Define a MarkupTemplate subclass with embedded HTML
 *   - Register the template as a singleton with WebApplication
 *   - Inject and use the template in endpoints
 *   - Use XPath selectors to find specific elements
 *   - Modify element content, attributes, and classes
 *   - Handle form POST to update the document state
 * 
 * This example complements DocumentBuilder.vala by showing template-based
 * document manipulation rather than building from scratch.
 * 
 * Usage: document-builder-template [port]
 */

// Application state - a simple counter
class AppState : Object {
    public int counter { get; set; }
    public int total_changes { get; set; }
    public string last_action { get; set; }
    public DateTime last_update { get; set; }
    
    public AppState() {
        counter = 0;
        total_changes = 0;
        last_action = "Initialized";
        last_update = new DateTime.now_local();
    }
    
    public void increment() {
        counter++;
        total_changes++;
        last_action = "Incremented";
        last_update = new DateTime.now_local();
    }
    
    public void decrement() {
        counter--;
        total_changes++;
        last_action = "Decremented";
        last_update = new DateTime.now_local();
    }
    
    public void reset() {
        counter = 0;
        total_changes++;
        last_action = "Reset";
        last_update = new DateTime.now_local();
    }
}

/**
 * CSS content for the counter page.
 * Served as a FastResource for optimal performance with pre-compression.
 */
private const string COUNTER_CSS = """
body {
    font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', Roboto, sans-serif;
    max-width: 700px;
    margin: 0 auto;
    padding: 20px;
    background: linear-gradient(135deg, #667eea 0%, #764ba2 100%);
    min-height: 100vh;
}
.card {
    background: white;
    border-radius: 12px;
    padding: 25px;
    margin: 15px 0;
    box-shadow: 0 10px 40px rgba(0,0,0,0.2);
}
h1 {
    color: #333;
    margin-top: 0;
}
.counter-display {
    text-align: center;
    padding: 30px;
    background: #f8f9fa;
    border-radius: 8px;
    margin: 20px 0;
}
.counter-value {
    font-size: 72px;
    font-weight: bold;
    color: #667eea;
    line-height: 1;
}
.counter-label {
    color: #666;
    font-size: 14px;
    text-transform: uppercase;
    letter-spacing: 2px;
}
.button-group {
    display: flex;
    gap: 10px;
    justify-content: center;
    margin: 20px 0;
}
button {
    padding: 12px 24px;
    border: none;
    border-radius: 6px;
    cursor: pointer;
    font-size: 16px;
    font-weight: 600;
    transition: all 0.2s;
}
button:hover {
    transform: translateY(-2px);
    box-shadow: 0 4px 12px rgba(0,0,0,0.15);
}
.btn-primary {
    background: #667eea;
    color: white;
}
.btn-primary:hover {
    background: #5a6fd6;
}
.btn-danger {
    background: #e74c3c;
    color: white;
}
.btn-danger:hover {
    background: #c0392b;
}
.btn-success {
    background: #2ecc71;
    color: white;
}
.btn-success:hover {
    background: #27ae60;
}
.info-grid {
    display: grid;
    grid-template-columns: repeat(2, 1fr);
    gap: 15px;
    margin: 20px 0;
}
.info-item {
    background: #f8f9fa;
    padding: 15px;
    border-radius: 6px;
    text-align: center;
}
.info-label {
    font-size: 12px;
    color: #666;
    text-transform: uppercase;
    letter-spacing: 1px;
}
.info-value {
    font-size: 18px;
    font-weight: 600;
    color: #333;
    margin-top: 5px;
}
.status-positive {
    color: #2ecc71 !important;
}
.status-negative {
    color: #e74c3c !important;
}
.status-zero {
    color: #666 !important;
}
code {
    background: #e8e8e8;
    padding: 2px 6px;
    border-radius: 4px;
    font-size: 14px;
}
pre {
    background: #263238;
    color: #aed581;
    padding: 15px;
    border-radius: 6px;
    overflow-x: auto;
    font-size: 13px;
}
.feature-list {
    margin: 0;
    padding-left: 20px;
}
.feature-list li {
    margin: 8px 0;
    color: #555;
}
a {
    color: #667eea;
    text-decoration: none;
}
a:hover {
    text-decoration: underline;
}
""";

/**
 * CounterTemplate - A cached HTML template for the counter page.
 * 
 * This class extends MarkupTemplate to provide a reusable, cached template.
 * The HTML is parsed once and cached; new_instance() returns efficient copies.
 * CSS is served separately via CounterStyles FastResource for optimal caching.
 */
class CounterTemplate : MarkupTemplate {
    /// <summary>
    /// Returns the HTML markup for this template.
    /// CSS is linked externally via /styles.css for better caching.
    /// </summary>
    protected override string markup { get {
        return """<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8"/>
    <meta name="viewport" content="width=device-width, initial-scale=1.0"/>
    <title>Document Template Example</title>
    <link rel="stylesheet" href="/styles.css"/>
</head>
<body>
    <div class="card" id="main-card">
        <h1 id="page-title">📄 Template Document Builder</h1>
        <p id="description">This page demonstrates loading an HTML template and modifying it dynamically.</p>
    </div>
    
    <div class="card" id="counter-card">
        <div class="counter-display">
            <div class="counter-label">Current Value</div>
            <div class="counter-value" id="counter-value">0</div>
        </div>
        
        <div class="button-group" id="button-group">
            <form method="POST" action="/decrement" style="display: inline;">
                <button type="submit" class="btn-danger">− Decrease</button>
            </form>
            <form method="POST" action="/reset" style="display: inline;">
                <button type="submit" class="btn-primary">↺ Reset</button>
            </form>
            <form method="POST" action="/increment" style="display: inline;">
                <button type="submit" class="btn-success">+ Increase</button>
            </form>
        </div>
        
        <div class="info-grid" id="info-grid">
            <div class="info-item" id="status-item">
                <div class="info-label">Status</div>
                <div class="info-value" id="status-value">Zero</div>
            </div>
            <div class="info-item" id="action-item">
                <div class="info-label">Last Action</div>
                <div class="info-value" id="action-value">Initialized</div>
            </div>
            <div class="info-item" id="time-item">
                <div class="info-label">Last Update</div>
                <div class="info-value" id="time-value">--:--:--</div>
            </div>
            <div class="info-item" id="count-item">
                <div class="info-label">Total Changes</div>
                <div class="info-value" id="changes-value">0</div>
            </div>
        </div>
    </div>
    
    <div class="card" id="code-card">
        <h2>How It Works</h2>
        <p>The server loads the HTML template and uses XPath selectors to find and modify elements:</p>
        
        <pre id="code-example">// Load the template
var doc = new MarkupDocument.from_string(HTML_TEMPLATE);

// Find and modify elements using XPath
var counter_el = doc.select_one("//div[@id='counter-value']");
counter_el.text_content = counter.to_string();

// Add/remove classes based on state
if (counter > 0) {
    counter_el.add_class("status-positive");
}</pre>
        
        <h3>DocumentModel Features Used:</h3>
        <ul class="feature-list" id="feature-list">
            <li><code>MarkupDocument.from_string()</code> - Load HTML from template</li>
            <li><code>doc.select_one(xpath)</code> - Find single element by XPath</li>
            <li><code>doc.select(xpath)</code> - Find multiple elements</li>
            <li><code>element.text_content</code> - Get/set text content</li>
            <li><code>element.add_class()/remove_class()</code> - Modify CSS classes</li>
            <li><code>element.set_attribute()</code> - Set element attributes</li>
            <li><code>doc.to_result()</code> - Return as HttpResult</li>
        </ul>
    </div>
    
    <div class="card" id="footer-card">
        <p style="text-align: center; color: #666; margin: 0;">
            Built with <code>Astralis.Document</code> | 
            <a href="/raw">View Raw HTML</a>
        </p>
    </div>
</body>
</html>
""";
    }}
}

// Main page endpoint - uses field initializer injection
class HomePageEndpoint : Object, Endpoint {
    // Field initializer injection - template is injected by the DI container
    private CounterTemplate template = Inversion.inject<CounterTemplate>();
    
    public async HttpResult handle_request(HttpContext context, RouteContext route) throws Error {
        // Get a copy of the cached template
        var doc = template.new_instance();
        
        // Update the counter value
        var counter_el = doc.select_one("//div[@id='counter-value']");
        if (counter_el != null) {
            counter_el.text_content = app_state.counter.to_string();
            
            // Update status class based on counter value
            counter_el.remove_class("status-positive");
            counter_el.remove_class("status-negative");
            counter_el.remove_class("status-zero");
            
            if (app_state.counter > 0) {
                counter_el.add_class("status-positive");
            } else if (app_state.counter < 0) {
                counter_el.add_class("status-negative");
            } else {
                counter_el.add_class("status-zero");
            }
        }
        
        // Update status text
        var status_el = doc.select_one("//div[@id='status-value']");
        if (status_el != null) {
            if (app_state.counter > 0) {
                status_el.text_content = "Positive";
                status_el.remove_class("status-negative");
                status_el.remove_class("status-zero");
                status_el.add_class("status-positive");
            } else if (app_state.counter < 0) {
                status_el.text_content = "Negative";
                status_el.remove_class("status-positive");
                status_el.remove_class("status-zero");
                status_el.add_class("status-negative");
            } else {
                status_el.text_content = "Zero";
                status_el.remove_class("status-positive");
                status_el.remove_class("status-negative");
                status_el.add_class("status-zero");
            }
        }
        
        // Update last action
        var action_el = doc.select_one("//div[@id='action-value']");
        if (action_el != null) {
            action_el.text_content = app_state.last_action;
        }
        
        // Update timestamp
        var time_el = doc.select_one("//div[@id='time-value']");
        if (time_el != null) {
            time_el.text_content = app_state.last_update.format("%H:%M:%S");
        }
        
        // Update total changes count
        var changes_el = doc.select_one("//div[@id='changes-value']");
        if (changes_el != null) {
            changes_el.text_content = app_state.total_changes.to_string();
        }
        
        return doc.to_result();
    }
}

// Increment endpoint
class IncrementEndpoint : Object, Endpoint {
    public async HttpResult handle_request(HttpContext context, RouteContext route) throws Error {
        app_state.increment();
        return new HttpStringResult("", (StatusCode)302)
            .set_header("Location", "/");
    }
}

// Decrement endpoint
class DecrementEndpoint : Object, Endpoint {
    public async HttpResult handle_request(HttpContext context, RouteContext route) throws Error {
        app_state.decrement();
        return new HttpStringResult("", (StatusCode)302)
            .set_header("Location", "/");
    }
}

// Reset endpoint
class ResetEndpoint : Object, Endpoint {
    public async HttpResult handle_request(HttpContext context, RouteContext route) throws Error {
        app_state.reset();
        return new HttpStringResult("", (StatusCode)302)
            .set_header("Location", "/");
    }
}

// Raw HTML endpoint - shows the unmodified template
class RawHtmlEndpoint : Object, Endpoint {
    // Field initializer injection
    private CounterTemplate template = Inversion.inject<CounterTemplate>();
    
    public async HttpResult handle_request(HttpContext context, RouteContext route) throws Error {
        // Get a fresh copy of the template
        var doc = template.new_instance();
        
        // Add a notice at the top
        var body = doc.body;
        if (body != null) {
            var notice = body.append_child_element("div");
            notice.set_attribute("style", "background: #fff3cd; color: #856404; padding: 15px; margin: 10px 0; border-radius: 8px; border: 1px solid #ffc107;");
            notice.append_text("⚠️ This is the raw template without dynamic modifications. ");
            var link = notice.append_child_element("a");
            link.set_attribute("href", "/");
            link.append_text("← Back to dynamic version");
        }
        
        return doc.to_result();
    }
}

// API endpoint that demonstrates modifying multiple elements at once
class BulkUpdateEndpoint : Object, Endpoint {
    // Field initializer injection
    private CounterTemplate template = Inversion.inject<CounterTemplate>();
    
    public async HttpResult handle_request(HttpContext context, RouteContext route) throws Error {
        var doc = template.new_instance();
        
        // Demonstrate selecting multiple elements and iterating
        var all_info_values = doc.select("//div[contains(@class, 'info-value')]");
        
        // Update all info values to show they were bulk-modified
        foreach (var node in all_info_values) {
            node.text_content = "BULK UPDATED";
            node.add_class("status-positive");
        }
        
        // Also demonstrate setting attributes on multiple elements
        var all_cards = doc.select("//div[contains(@class, 'card')]");
        foreach (var card in all_cards) {
            card.set_attribute("data-bulk-update", "true");
        }
        
        // Update title to indicate bulk operation
        var title = doc.select_one("//h1[@id='page-title']");
        if (title != null) {
            title.text_content = "📄 Bulk Update Demo";
        }
        
        // Add explanation
        var desc = doc.select_one("//p[@id='description']");
        if (desc != null) {
            desc.text_content = "This demonstrates Enumerable<MarkupNode> iteration for bulk operations.";
        }
        
        return doc.to_result();
    }
}

// Global app state
AppState app_state;

void main(string[] args) {
    int port = args.length > 1 ? int.parse(args[1]) : 8080;
    
    // Initialize app state
    app_state = new AppState();
    
    print("╔══════════════════════════════════════════════════════════════╗\n");
    print("║          Astralis DocumentBuilderTemplate Example           ║\n");
    print("╠══════════════════════════════════════════════════════════════╣\n");
    print(@"║  Port: $port");
    for (int i = 0; i < 50 - port.to_string().length - 7; i++) print(" ");
    print(" ║\n");
    print("╠══════════════════════════════════════════════════════════════╣\n");
    print("║  Endpoints:                                                  ║\n");
    print("║    /           - Counter page (template with modifications)  ║\n");
    print("║    /styles.css - CSS stylesheet (FastResource)               ║\n");
    print("║    /increment  - Increase counter (POST)                     ║\n");
    print("║    /decrement  - Decrease counter (POST)                     ║\n");
    print("║    /reset      - Reset counter (POST)                        ║\n");
    print("║    /raw        - Raw template (no modifications)             ║\n");
    print("║    /bulk       - Bulk update demo                            ║\n");
    print("╚══════════════════════════════════════════════════════════════╝\n");
    print("\nPress Ctrl+C to stop the server\n\n");
    
    try {
        var application = new WebApplication(port);
        
        // Register compression components
        application.use_compression();
        
        // Register the template as a singleton - it will be parsed once and cached
        // Each request gets a copy via new_instance()
        // Endpoints use field initializer injection with Inversion.inject<T>()
        application.add_startup<CounterTemplate>();
        
        // Register CSS as a FastResource - pre-compressed, cached in memory
        // This demonstrates serving static content efficiently with ETag caching
        application.add_startup_endpoint<FastResource>(new EndpointRoute("/styles.css"), () => {
            try {
                return new FastResource.from_string(COUNTER_CSS)
                    .with_content_type("text/css; charset=utf-8")
                    .with_default_compressors();
            } catch (Error e) {
                error("Failed to create CSS resource: %s", e.message);
            }
        });
        
        // Register endpoints
        application.add_endpoint<HomePageEndpoint>(new EndpointRoute("/"));
        application.add_endpoint<IncrementEndpoint>(new EndpointRoute("/increment"));
        application.add_endpoint<DecrementEndpoint>(new EndpointRoute("/decrement"));
        application.add_endpoint<ResetEndpoint>(new EndpointRoute("/reset"));
        application.add_endpoint<RawHtmlEndpoint>(new EndpointRoute("/raw"));
        application.add_endpoint<BulkUpdateEndpoint>(new EndpointRoute("/bulk"));
        
        application.run();
        
    } catch (Error e) {
        printerr("Error: %s\n", e.message);
        Process.exit(1);
    }
}