/**
 * 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_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}")`);
        }
    }

    // ===== 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);
            }
        }
    }

    updateSignalDisplay(signalName, value) {
        // Find DOM elements that should display this signal
        // For now, update any element with class matching signal name or data-signal attribute
        const selectors = [
            `[data-signal="${signalName}"]`,
            `.${signalName}`,
            '.count', // Hardcoded for demo - TODO: track bindings properly
        ];

        selectors.forEach(selector => {
            const elements = document.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(`Marker ${markerId} not found`);
            return;
        }

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

        // Remove old node if it exists (0 means no old node)
        if (oldNodeId !== 0) {
            const oldNode = this.nodes.get(oldNodeId);
            if (oldNode && oldNode.parentNode) {
                oldNode.parentNode.removeChild(oldNode);
                this._log(`Removed old node ${oldNodeId}`);
            }
        }

        // Insert new node after marker (only if newNodeId is not 0)
        if (newNodeId !== 0) {
            const newNode = this.nodes.get(newNodeId);
            if (!newNode) {
                console.error(`New node ${newNodeId} not found`);
                return;
            }
            parent.insertBefore(newNode, marker.nextSibling);
            this._log(`Inserted node ${newNodeId} at marker ${markerId}`);
        }
    }

    // ===== 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.onLoad = options.onLoad || (() => {});
        this.onError = options.onError || ((err) => console.error(err));
    }

    async load(wasmPath, componentName, props = {}) {
        try {
            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_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_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 render function with props
            const renderFn = instance.exports[`render_${componentName}`];
            if (!renderFn) {
                throw new Error(`render_${componentName} not found in WASM exports`);
            }

            // Pass props as positional arguments
            const propValues = Object.values(props);
            renderFn(...propValues);

            // 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);

            return { runtime, instance };

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

    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;
}