/**
 * Home Automation API Client
 * 
 * Provides a unified interface to interact with the backend API.
 * All functions use the global window.API_BASE configuration.
 */

class HomeAutomationClient {
    /**
     * Get layout info for a specific device
     * @param {string} deviceId - Device ID
     * @returns {Promise<object>} Layout info
     */
    async getDeviceLayout(deviceId) {
        return await this.fetch(this.api(`/devices/${deviceId}/layout`));
    }
    constructor() {
        this.eventSource = null;
        this.eventListeners = [];
    }

    /**
     * Helper to construct full API URLs
     * Reads window.API_BASE at runtime to support dynamic configuration
     * @param {string} path - API path (e.g., '/devices')
     * @returns {string} Full URL
     */
    api(path) {
        const baseUrl = window.API_BASE || '';
        return `${baseUrl}${path}`;
    }

    /**
     * Generic fetch wrapper with error handling
     * @param {string} url - URL to fetch
     * @param {object} options - Fetch options
     * @returns {Promise<any>} Response data
     */
    async fetch(url, options = {}) {
        try {
            const response = await fetch(url, {
                ...options,
                headers: {
                    'Content-Type': 'application/json',
                    ...options.headers
                }
            });

            if (!response.ok) {
                throw new Error(`API error: ${response.status} ${response.statusText}`);
            }

            return await response.json();
        } catch (error) {
            console.error('API request failed:', error);
            throw error;
        }
    }

    /**
     * Get layout data (rooms and their devices)
     * @returns {Promise<{rooms: Array<{name: string, devices: string[]}>}>}
     */
    async getLayout() {
        return await this.fetch(this.api('/layout'));
    }

    /**
     * Get all devices with their features
     * @returns {Promise<Array<{device_id: string, name: string, type: string, features: object}>>}
     */
    async getDevices() {
        return await this.fetch(this.api('/devices'));
    }

    async getDevice(deviceId) {
        return await this.fetch(this.api(`/devices/${deviceId}`));
    }

    /**
     * Get current state of a specific device
     * @param {string} deviceId - Device ID
     * @returns {Promise<object>} Device state
     */
    async getDeviceState(deviceId) {
        return await this.fetch(this.api(`/devices/${deviceId}/state`));
    }

    /**
     * Get all device states at once
     * @returns {Promise<object>} Map of device_id to state
     */
    async getAllStates() {
        return await this.fetch(this.api('/devices/states'));
    }

    /**
     * Send a command to a device
     * @param {string} deviceId - Device ID
     * @param {string} type - Device type (light, thermostat, etc.)
     * @param {object} payload - Command payload
     * @returns {Promise<void>}
     */
    async setDeviceState(deviceId, type, payload) {
        await fetch(this.api(`/devices/${deviceId}/set`), {
            method: 'POST',
            headers: {
                'Content-Type': 'application/json'
            },
            body: JSON.stringify({ type, payload })
        });
    }

    /**
     * Get room information for a device
     * @param {string} deviceId - Device ID
     * @returns {Promise<{room: string}>}
     */
    async getDeviceRoom(deviceId) {
        return await this.fetch(this.api(`/devices/${deviceId}/room`));
    }

    /**
     * Get all available scenes
     * @returns {Promise<Array<{scene_id: string, name: string, devices: object}>>}
     */
    async getScenes() {
        return await this.fetch(this.api('/scenes'));
    }

    /**
     * Activate a scene
     * @param {string} sceneId - Scene ID
     * @returns {Promise<void>}
     */
    async activateScene(sceneId) {
        await fetch(this.api(`/scenes/${sceneId}/activate`), {
            method: 'POST'
        });
    }

    /**
     * Connect to realtime event stream (SSE)
     * @param {Function} onEvent - Callback function(event)
     * @param {Function} onError - Error callback (optional)
     * @returns {EventSource} EventSource instance
     */
    connectRealtime(onEvent, onError = null) {
        if (this.eventSource) {
            this.eventSource.close();
        }

        this.eventSource = new EventSource(this.api('/realtime'));

        this.eventSource.onmessage = (event) => {
            try {
                const data = JSON.parse(event.data);
                
                // Normalize event format: convert API format to unified format
                const normalizedEvent = {
                    device_id: data.device_id,
                    type: data.type,
                    state: data.payload || data.state  // Support both formats
                };
                
                onEvent(normalizedEvent);
                
                // Notify all registered listeners
                this.eventListeners.forEach(listener => {
                    if (!listener.deviceId || listener.deviceId === normalizedEvent.device_id) {
                        listener.callback(normalizedEvent);
                    }
                });
            } catch (error) {
                console.error('Failed to parse SSE event:', error);
            }
        };

        this.eventSource.onerror = (error) => {
            console.error('SSE connection error:', error);
            if (onError) {
                onError(error);
            }
            
            // Auto-reconnect after 5 seconds
            setTimeout(() => {
                if (this.eventSource) {
                    this.eventSource.close();
                    this.connectRealtime(onEvent, onError);
                }
            }, 5000);
        };

        return this.eventSource;
    }

    /**
     * Register a listener for specific device updates
     * @param {string|null} deviceId - Device ID or null for all devices
     * @param {Function} callback - Callback function(event)
     * @returns {Function} Unsubscribe function
     */
    onDeviceUpdate(deviceId, callback) {
        const listener = { deviceId, callback };
        this.eventListeners.push(listener);

        // Return unsubscribe function
        return () => {
            const index = this.eventListeners.indexOf(listener);
            if (index > -1) {
                this.eventListeners.splice(index, 1);
            }
        };
    }

    /**
     * Disconnect from realtime stream
     */
    disconnectRealtime() {
        if (this.eventSource) {
            this.eventSource.close();
            this.eventSource = null;
        }
        this.eventListeners = [];
    }

    /**
     * Helper: Get device by ID from devices array
     * @param {Array} devices - Devices array
     * @param {string} deviceId - Device ID to find
     * @returns {object|null} Device object or null
     */
    findDevice(devices, deviceId) {
        return devices.find(d => d.device_id === deviceId) || null;
    }

    /**
     * Helper: Get room by name from layout
     * @param {object} layout - Layout object
     * @param {string} roomName - Room name to find
     * @returns {object|null} Room object or null
     */
    findRoom(layout, roomName) {
        return layout.rooms.find(r => r.name === roomName) || null;
    }

    /**
     * Helper: Get devices for a specific room
     * @param {object} layout - Layout object
     * @param {Array} devices - Devices array
     * @param {string} roomName - Room name
     * @returns {Array} Array of device objects
     */
    getDevicesForRoom(layout, devices, roomName) {
        const room = this.findRoom(layout, roomName);
        if (!room) return [];

        const deviceMap = {};
        devices.forEach(d => deviceMap[d.device_id] = d);

        // Extract device IDs from room.devices (they are objects with device_id property)
        const deviceIds = room.devices.map(d => d.device_id || d);
        
        return deviceIds
            .map(id => deviceMap[id])
            .filter(d => d != null);
    }
}

// Create global instance
window.apiClient = new HomeAutomationClient();

/**
 * Convenience function for backward compatibility
 */
function api(url) {
    return window.apiClient.api(url);
}