/**
 * Ritz Runtime - WebAssembly DOM Bridge
 *
 * Provides the runtime environment for Ritz components compiled to WASM.
 */

class RitzRuntime {
    constructor(rootElement) {
        this.rootElement = rootElement || document.getElementById('app');
        this.nodes = new Map();
        this.nextNodeId = 1;
        this.log = [];
        this.wasmInstance = null;
        this.debugEnabled = true;
    }

    // ===== DOM Manipulation Bridge =====

    js_create_element(tagPtr) {
        const tag = this.readString(tagPtr);
        const element = document.createElement(tag);
        const id = this.nextNodeId++;
        this.nodes.set(id, element);
        this._log(`createElement("${tag}") = ${id}`);
        return id;
    }

    js_create_text(textPtr) {
        const text = this.readString(textPtr);
        const textNode = document.createTextNode(text);
        const id = this.nextNodeId++;
        this.nodes.set(id, textNode);
        this._log(`createTextNode("${text}") = ${id}`);
        return id;
    }

    js_append_child(parentId, childId) {
        const parent = this.nodes.get(parentId);
        const child = this.nodes.get(childId);
        if (parent && child) {
            parent.appendChild(child);
            this._log(`appendChild(${parentId}, ${childId})`);
        }
    }

    js_set_attribute(elemId, namePtr, valuePtr) {
        const element = this.nodes.get(elemId);
        const name = this.readString(namePtr);
        const value = this.readString(valuePtr);
        if (element) {
            if (name === 'class') {
                element.className = value;
            } else {
                element.setAttribute(name, value);
            }
            this._log(`setAttribute(${elemId}, "${name}", "${value}")`);
        }
    }

    js_bind_event(elemId, eventNamePtr, handlerNamePtr) {
        const element = this.nodes.get(elemId);
        const eventName = this.readString(eventNamePtr);
        const handlerName = this.readString(handlerNamePtr);

        if (element && this.wasmInstance) {
            const handler = this.wasmInstance.exports[handlerName];
            if (handler) {
                element.addEventListener(eventName, () => {
                    this._log(`[Event] ${eventName} → ${handlerName}()`);
                    handler();
                    this.updateSignals();
                });
                this._log(`bindEvent(${elemId}, "${eventName}", "${handlerName}")`);
            } else {
                console.error(`Handler ${handlerName} not found in WASM exports`);
            }
        }
    }

    js_toggle_debug_console() {
        // Bridge function to toggle debug console from WASM
        if (window.ritzLoader) {
            window.ritzLoader.toggleDebugConsole();
        }
        this._log('[Debug] Toggle debug console from WASM');
    }

    js_set_root(elemId) {
        const element = this.nodes.get(elemId);
        if (element) {
            this.rootElement.innerHTML = '';
            this.rootElement.appendChild(element);
            this._log(`setRoot(${elemId})`);
        }
    }

    js_update_text_content(nodeId, textPtr) {
        const node = this.nodes.get(nodeId);
        const text = this.readString(textPtr);
        if (node) {
            node.textContent = text;
            this._log(`updateTextContent(${nodeId}, "${text}")`);
        }
    }

    js_create_text_with_int(prefixPtr, intValue) {
        const prefix = this.readString(prefixPtr);
        const text = prefix + intValue.toString();
        const textNode = document.createTextNode(text);
        const id = this.nextNodeId++;
        this.nodes.set(id, textNode);
        this._log(`createTextWithInt("${prefix}", ${intValue}) = "${text}" (id=${id})`);
        return id;
    }

    js_update_text_with_int(nodeId, prefixPtr, intValue) {
        const node = this.nodes.get(nodeId);
        const prefix = this.readString(prefixPtr);
        const text = prefix + intValue.toString();
        if (node) {
            node.textContent = text;
            this._log(`updateTextWithInt(${nodeId}, "${prefix}", ${intValue}) = "${text}"`);
        }
    }

    // ===== Signal Management =====

    updateSignals() {
        // Discover and update all signals
        if (!this.wasmInstance) return;

        const exports = this.wasmInstance.exports;

        // Find all get_* functions (signal getters)
        for (const [name, fn] of Object.entries(exports)) {
            if (name.startsWith('get_') && typeof fn === 'function') {
                const signalName = name.substring(4); // Remove 'get_' prefix
                const value = fn();
                this._log(`[Signal] ${signalName} = ${value}`);

                // Update DOM elements bound to this signal
                // TODO: Track signal-to-DOM bindings during render for efficiency
                this.updateSignalDisplay(signalName, value);
            }
        }

        // Re-evaluate all reactive conditionals
        for (const [name, fn] of Object.entries(exports)) {
            if (name.startsWith('reevaluate_conditional_') && typeof fn === 'function') {
                fn();
                this._log(`[Reactive] ${name}()`);
            }
        }

        // Re-evaluate all reactive match statements
        for (const [name, fn] of Object.entries(exports)) {
            if (name.startsWith('reevaluate_match_') && typeof fn === 'function') {
                fn();
                this._log(`[Reactive] ${name}()`);
            }
        }

        // Update debug console stats if debug mode is enabled
        if (window.ritzLoader && this.debugEnabled) {
            window.ritzLoader.updateDebugStats();
        }
    }

    updateSignalDisplay(signalName, value) {
        // Find DOM elements that should display this signal
        // IMPORTANT: Only search within this runtime's root element to avoid cross-contamination
        const selectors = [
            `[data-signal="${signalName}"]`,
            `.${signalName}`,
            '.count', // Hardcoded for demo - TODO: track bindings properly
        ];

        selectors.forEach(selector => {
            // Only query within this runtime's root element, not the entire document
            const elements = this.rootElement.querySelectorAll(selector);
            elements.forEach(el => {
                // Check if text contains the signal name or looks like a counter
                const text = el.textContent;
                if (text.includes(signalName) || text.match(/\d+/)) {
                    // Replace the number in the text
                    el.textContent = text.replace(/\d+/, value);
                }
            });
        });
    }

    // ===== Reactive Conditional Rendering =====

    js_create_marker() {
        // Create a comment node as a marker for conditional insertion
        const marker = document.createComment('conditional-marker');
        const id = this.nextNodeId++;
        this.nodes.set(id, marker);
        this._log(`Created marker node ${id}`);
        return id;
    }

    js_replace_at_marker(markerId, oldNodeId, newNodeId) {
        // Replace DOM node at marker position
        const marker = this.nodes.get(markerId);
        if (!marker) {
            console.error(`[replace_at_marker] Marker ${markerId} not found`);
            return;
        }

        const parent = marker.parentNode;
        if (!parent) {
            console.error(`[replace_at_marker] Marker ${markerId} has no parent`);
            return;
        }

        this._log(`[replace_at_marker] marker=${markerId}, old=${oldNodeId}, new=${newNodeId}`);

        // Remove old node if it exists (0 means no old node to remove)
        if (oldNodeId !== 0) {
            const oldNode = this.nodes.get(oldNodeId);
            if (!oldNode) {
                console.warn(`[replace_at_marker] Old node ${oldNodeId} not found in registry`);
            } else if (!oldNode.parentNode) {
                console.warn(`[replace_at_marker] Old node ${oldNodeId} not in DOM`);
            } else if (oldNode.parentNode !== parent) {
                console.warn(`[replace_at_marker] Old node ${oldNodeId} in wrong parent`);
                oldNode.parentNode.removeChild(oldNode);
                this._log(`[replace_at_marker] Removed ${oldNodeId} from wrong parent`);
            } else {
                // Remove from correct parent
                parent.removeChild(oldNode);
                this._log(`[replace_at_marker] Removed ${oldNodeId} from correct parent`);
            }
        }

        // Insert new node after marker (only if newNodeId is not 0)
        if (newNodeId !== 0) {
            const newNode = this.nodes.get(newNodeId);
            if (!newNode) {
                console.error(`[replace_at_marker] New node ${newNodeId} not found`);
                return;
            }

            // Insert right after the marker
            // If newNode is already in DOM elsewhere, this will move it
            const nextSibling = marker.nextSibling;
            if (nextSibling) {
                parent.insertBefore(newNode, nextSibling);
                this._log(`[replace_at_marker] Inserted ${newNodeId} before sibling`);
            } else {
                parent.appendChild(newNode);
                this._log(`[replace_at_marker] Appended ${newNodeId} (no sibling)`);
            }
        }
    }

    // ===== Memory & String Utilities =====

    readString(ptr) {
        if (!this.memory) return '';
        const bytes = new Uint8Array(this.memory.buffer, ptr);
        let length = 0;
        while (bytes[length] !== 0) length++;
        return new TextDecoder().decode(bytes.slice(0, length));
    }

    setMemory(memory) {
        this.memory = memory;
    }

    setWasmInstance(instance) {
        this.wasmInstance = instance;
    }

    // ===== Logging & Debug =====

    _log(message) {
        if (this.debugEnabled) {
            this.log.push(message);
        }
    }

    getLog() {
        return this.log;
    }

    clearLog() {
        this.log = [];
    }
}


/**
 * RitzLoader - Simplified WASM loading
 */
class RitzLoader {
    constructor(options = {}) {
        this.rootElement = options.rootElement || document.getElementById('app');
        this.statusElement = options.statusElement || document.getElementById('status');
        this.debug = options.debug !== undefined ? options.debug : false;
        this.onLoad = options.onLoad || (() => {});
        this.onError = options.onError || ((err) => console.error(err));
        this.debugConsoleRuntime = null;
    }

    async load(wasmPath, componentName = null, props = {}) {
        try {
            // Auto-detect component name from wasm filename if not provided
            if (!componentName) {
                // Extract from path: "Main.wasm" → "Main", "path/to/Main.wasm" → "Main"
                componentName = wasmPath.split('/').pop().replace('.wasm', '');
            }

            this.setStatus('⏳ Creating runtime...');
            const runtime = new RitzRuntime(this.rootElement);

            this.setStatus(`⏳ Loading ${wasmPath}...`);
            const response = await fetch(wasmPath);
            if (!response.ok) {
                throw new Error(`Failed to load ${wasmPath}: ${response.status}`);
            }

            const wasmBytes = await response.arrayBuffer();

            this.setStatus('⏳ Instantiating WASM...');

            // Create imports for WASM
            const imports = {
                env: {
                    js_create_element: (ptr) => runtime.js_create_element(ptr),
                    js_create_text: (ptr) => runtime.js_create_text(ptr),
                    js_create_text_with_int: (p, i) => runtime.js_create_text_with_int(p, i),
                    js_append_child: (p, c) => runtime.js_append_child(p, c),
                    js_set_attribute: (e, n, v) => runtime.js_set_attribute(e, n, v),
                    js_set_root: (e) => runtime.js_set_root(e),
                    js_bind_event: (e, n, h) => runtime.js_bind_event(e, n, h),
                    js_update_text_content: (n, t) => runtime.js_update_text_content(n, t),
                    js_update_text_with_int: (n, p, i) => runtime.js_update_text_with_int(n, p, i),
                    js_create_marker: () => runtime.js_create_marker(),
                    js_replace_at_marker: (m, o, n) => runtime.js_replace_at_marker(m, o, n),
                }
            };

            const { instance } = await WebAssembly.instantiate(wasmBytes, imports);

            // Setup runtime
            runtime.setMemory(instance.exports.memory);
            runtime.setWasmInstance(instance);

            this.setStatus(`⏳ Rendering ${componentName}...`);

            // Call the main entry point (which renders top-level component and sets root)
            const mainFn = instance.exports.main;
            if (!mainFn) {
                throw new Error(`main function not found in WASM exports`);
            }

            mainFn();

            // Update signals
            runtime.updateSignals();

            this.setStatus(`✅ ${componentName} loaded!`, 'success');

            // Make runtime globally available for debugging
            window.ritzRuntime = runtime;
            window.ritzInstance = instance;

            this.onLoad(runtime, instance);

            // Load debug console if debug mode is enabled
            if (this.debug) {
                await this.loadDebugConsole(componentName);
            }

            return { runtime, instance };

        } catch (error) {
            this.setStatus(`❌ Error: ${error.message}`, 'error');
            this.onError(error);
            throw error;
        }
    }

    async loadDebugConsole(appComponentName) {
        try {
            console.log('[Debug] Loading debug console...');

            // Create a container for the debug console
            const debugContainer = document.createElement('div');
            debugContainer.id = 'debug-console-root';
            document.body.appendChild(debugContainer);

            console.log('[Debug] Created container:', debugContainer);

            // Create debug console runtime
            const debugRuntime = new RitzRuntime(debugContainer);
            debugRuntime.debugEnabled = false; // Don't log debug console's own operations

            // Load DebugConsole.wasm from runtime directory
            const debugWasmPath = '../runtime/DebugConsole.wasm';
            console.log('[Debug] Fetching:', debugWasmPath);

            const response = await fetch(debugWasmPath);
            if (!response.ok) {
                console.warn('Could not load debug console:', response.status);
                return;
            }

            console.log('[Debug] DebugConsole.wasm loaded successfully');

            const wasmBytes = await response.arrayBuffer();

            // Create imports for debug console WASM
            const imports = {
                env: {
                    js_create_element: (ptr) => debugRuntime.js_create_element(ptr),
                    js_create_text: (ptr) => debugRuntime.js_create_text(ptr),
                    js_create_text_with_int: (p, i) => debugRuntime.js_create_text_with_int(p, i),
                    js_append_child: (p, c) => debugRuntime.js_append_child(p, c),
                    js_set_attribute: (e, n, v) => debugRuntime.js_set_attribute(e, n, v),
                    js_set_root: (e) => debugRuntime.js_set_root(e),
                    js_bind_event: (e, n, h) => debugRuntime.js_bind_event(e, n, h),
                    js_update_text_content: (n, t) => debugRuntime.js_update_text_content(n, t),
                    js_update_text_with_int: (n, p, i) => debugRuntime.js_update_text_with_int(n, p, i),
                    js_create_marker: () => debugRuntime.js_create_marker(),
                    js_replace_at_marker: (m, o, n) => debugRuntime.js_replace_at_marker(m, o, n),
                    js_toggle_debug_console: () => debugRuntime.js_toggle_debug_console(),
                }
            };

            const { instance } = await WebAssembly.instantiate(wasmBytes, imports);

            // Setup debug runtime
            debugRuntime.setMemory(instance.exports.memory);
            debugRuntime.setWasmInstance(instance);

            // Render debug console
            console.log('[Debug] Rendering debug console...');
            instance.exports.main();
            debugRuntime.updateSignals();

            this.debugConsoleRuntime = debugRuntime;

            console.log('[Debug] Debug console rendered. Checking DOM...');
            const debugElement = document.querySelector('.ritz-debug');
            console.log('[Debug] Debug element:', debugElement);
            console.log('[Debug] Debug element classes:', debugElement?.className);

            // Hide the loader status element (we have our own in debug console)
            if (this.statusElement) {
                this.statusElement.style.display = 'none';
            }

            // Populate runtime stats
            this.updateDebugStats(appComponentName);

            // Setup keyboard shortcut (Ctrl+`)
            document.addEventListener('keydown', (e) => {
                if (e.ctrlKey && e.key === '`') {
                    e.preventDefault();
                    console.log('[Debug] Toggle debug console');
                    this.toggleDebugConsole();
                }
            });

            // Make debug console and loader globally available
            window.ritzDebugConsole = debugRuntime;
            window.ritzLoader = this;

            console.log('🎭 Ritz Debug Console loaded! Press Ctrl+` to toggle.');

        } catch (error) {
            console.warn('Failed to load debug console:', error);
        }
    }

    toggleDebugConsole() {
        // Toggle the debug console by toggling body class
        // The Ritz debug console component manages its own visibility via signal
        // But we need to trigger the body class for layout
        document.body.classList.toggle('debug-open');

        // Find the debug console element and toggle its hidden class
        const debugElement = document.querySelector('.ritz-debug');
        if (debugElement) {
            debugElement.classList.toggle('hidden');
        }
    }

    updateDebugStats(componentName = 'Main') {
        // Update status with component name (inside debug console)
        const statusEl = document.querySelector('#ritz-debug .status');
        if (statusEl) {
            statusEl.textContent = `✅ ${componentName} loaded!`;
            statusEl.className = 'status success';
        }

        // Update component section
        const componentPre = document.querySelector('#ritz-debug .debug-section:nth-child(1) pre');
        if (componentPre && window.ritzInstance) {
            const wasmSize = window.ritzInstance.exports.memory.buffer.byteLength;
            componentPre.textContent = `${componentName}.wasm (${Math.round(wasmSize / 1024)}KB)`;
        }

        // Update runtime stats
        const statsPre = document.querySelector('#ritz-debug .debug-section:nth-child(3) pre');
        if (statsPre && window.ritzRuntime && window.ritzInstance) {
            const memory = window.ritzInstance.exports.memory.buffer.byteLength;
            const memoryKB = Math.round(memory / 1024);
            const memoryMB = (memory / 1024 / 1024).toFixed(2);
            const nodeCount = window.ritzRuntime.nodes.size;

            // Count signals (globals that start with @signal_)
            const exports = Object.keys(window.ritzInstance.exports);
            const signalCount = exports.filter(name =>
                name.startsWith('get_') || name.startsWith('set_')
            ).length / 2;

            statsPre.textContent =
                `Memory: ${memoryKB}KB (${memoryMB}MB)\n` +
                `Signals: ${signalCount} reactive\n` +
                `DOM nodes: ${nodeCount} cached\n` +
                `Log entries: ${window.ritzRuntime.log.length}`;
        }
    }

    setStatus(message, type = '') {
        if (this.statusElement) {
            this.statusElement.textContent = message;
            this.statusElement.className = 'status ' + type;
        }
    }
}


// Export for use in modules or global scope
if (typeof module !== 'undefined' && module.exports) {
    module.exports = { RitzRuntime, RitzLoader };
} else {
    window.RitzRuntime = RitzRuntime;
    window.RitzLoader = RitzLoader;
}