// Screen Reader Announcements Module
// Handles ARIA live region announcements for accessibility
(function() {
    'use strict';

    AppModules.require('ui-controls');
    AppModules.register('screen-reader');

    // Announcement regions
    let regions = {};

    // State tracking to avoid announcement spam
    let lastViewerCount = 0;
    let lastStreamStatus = 'unknown';
    let lastConnectionStatus = 'unknown';

    // Announcement queue to prevent rapid-fire announcements
    let announcementQueue = [];
    let isProcessingQueue = false;

    // Configuration
    const ANNOUNCEMENT_THRESHOLDS = {
        viewerCount: 5, // Only announce when count changes by 5+ users
        messageGroup: 3, // Minimum messages for group announcements
        activityDelay: 500 // Delay for activity announcements to batch them
    };

    // Initialize announcement regions
    function initializeAnnouncements() {
        // Get all announcement region elements
        regions = {
            stream: document.getElementById('sr-stream-announcer'),
            connection: document.getElementById('sr-connection-announcer'),
            system: document.getElementById('sr-system-announcer'),
            messageGroup: document.getElementById('sr-message-group-announcer'),
            viewer: document.getElementById('sr-viewer-announcer'),
            activity: document.getElementById('sr-activity-announcer'),
            form: document.getElementById('sr-form-announcer')
        };

        // Verify all regions exist
        const missingRegions = Object.entries(regions).filter(([key, element]) => !element);
        if (missingRegions.length > 0) {
            AppLogger.error('Missing screen reader announcement regions:', missingRegions.map(([key]) => key));
        } else {
            AppLogger.log('Screen reader announcement regions initialized');
        }
    }

    // Queue announcement to prevent spam
    function queueAnnouncement(region, text, options = {}) {
        if (!text || !text.trim()) return;

        announcementQueue.push({
            region,
            text: text.trim(),
            options: {
                priority: options.priority || 'normal', // 'low', 'normal', 'high'
                delay: options.delay || 0,
                ...options
            }
        });

        // Start processing queue if not already running
        if (!isProcessingQueue) {
            processAnnouncementQueue();
        }
    }

    // Process the announcement queue
    async function processAnnouncementQueue() {
        if (isProcessingQueue || announcementQueue.length === 0) return;

        isProcessingQueue = true;

        while (announcementQueue.length > 0) {
            const announcement = announcementQueue.shift();

            try {
                await announce(announcement.region, announcement.text, announcement.options);
            } catch (error) {
                AppLogger.error('Error processing announcement:', error);
            }
        }

        isProcessingQueue = false;
    }

    // Actually announce to a region
    async function announce(regionName, text, options = {}) {
        const regionElement = regions[regionName];
        if (!regionElement) {
            AppLogger.error(`Unknown announcement region: ${regionName}`);
            return;
        }

        // Apply delay if specified
        if (options.delay > 0) {
            await new Promise(resolve => setTimeout(resolve, options.delay));
        }

        // Clear region first for assertive updates
        regionElement.textContent = '';

        // Small delay to ensure clear is processed
        await new Promise(resolve => setTimeout(resolve, 10));

        // Set the announcement text
        regionElement.textContent = text;

        // Log for debugging
        AppLogger.log(`Screen reader announcement (${regionName}): ${text}`);
    }

    // Public announcement functions
    const announcements = {

        // Stream status changes
        streamStatus(status, details = '') {
            if (status === lastStreamStatus) return; // Avoid duplicate announcements

            lastStreamStatus = status;
            let message = '';

            switch (status) {
                case 'online':
                    message = 'Stream is now online and available';
                    break;
                case 'offline':
                    message = 'Stream is currently offline';
                    break;
                case 'reconnecting':
                    message = 'Attempting to reconnect to stream';
                    break;
                case 'quality-changed':
                    message = `Stream quality changed to ${details}`;
                    break;
                case 'buffering':
                    message = 'Stream is buffering';
                    break;
            }

            if (message) {
                queueAnnouncement('stream', message, { priority: 'high' });
            }
        },

        // Connection status changes
        connectionStatus(status, details = '') {
            if (status === lastConnectionStatus) return;

            lastConnectionStatus = status;
            let message = '';

            switch (status) {
                case 'connected':
                    message = 'Chat connection established';
                    break;
                case 'disconnected':
                    message = 'Chat connection lost - attempting to reconnect';
                    break;
                case 'reconnecting':
                    message = 'Reconnecting to chat';
                    break;
                case 'error':
                    message = `Connection error: ${details}`;
                    break;
            }

            if (message) {
                queueAnnouncement('connection', message, { priority: 'high' });
            }
        },

        // Viewer count changes (with threshold)
        viewerCount(count) {
            const oldCount = lastViewerCount;
            const diff = Math.abs(count - oldCount);

            // Only announce if significant change (threshold) or crossing boundaries
            if (diff >= ANNOUNCEMENT_THRESHOLDS.viewerCount ||
                (oldCount === 0 && count > 0) ||
                (oldCount > 0 && count === 0)) {

                lastViewerCount = count;

                let message;
                if (count === 0) {
                    message = 'No viewers currently online';
                } else if (count === 1) {
                    message = '1 viewer online';
                } else {
                    message = `${count} viewers online`;
                }

                queueAnnouncement('viewer', message, { priority: 'low', delay: 500 });
            }
        },

        // System announcements (admin actions, etc.)
        systemMessage(message, priority = 'normal') {
            queueAnnouncement('system', message, {
                priority: priority,
                delay: priority === 'high' ? 0 : 200
            });
        },

        // Message group announcements
        messageGroup(messages, action = 'added') {
            if (!Array.isArray(messages) || messages.length === 0) return;

            const count = messages.length;
            let message = '';

            if (count >= ANNOUNCEMENT_THRESHOLDS.messageGroup) {
                if (action === 'added') {
                    message = `${count} new messages loaded`;
                } else if (action === 'filtered') {
                    message = `Showing ${count} messages matching filter`;
                }
            }

            if (message) {
                queueAnnouncement('messageGroup', message, {
                    priority: 'low',
                    delay: 300
                });
            }
        },

        // Individual message arrival (for existing messages)
        messageReceived(message, isUserMessage = false) {
            // Don't announce user's own messages to avoid echo feedback
            if (isUserMessage) return;

            // For individual messages, let the aria-live="polite" on chat handle it
            // Only use this for special announcements
        },

        // Activity announcements
        activity(userAction, details = '') {
            let message = '';

            switch (userAction) {
                case 'joined':
                    message = `User ${details} joined the chat`;
                    break;
                case 'left':
                    message = `User ${details} left the chat`;
                    break;
                case 'admin-action':
                    message = details; // Admin actions passed through
                    break;
                default:
                    if (details) {
                        message = details;
                    }
            }

            if (message) {
                queueAnnouncement('activity', message, {
                    priority: 'low',
                    delay: ANNOUNCEMENT_THRESHOLDS.activityDelay
                });
            }
        },

        // Form validation messages
        formValidation(field, isValid, message) {
            if (!message) return;

            queueAnnouncement('form', message, {
                priority: isValid ? 'low' : 'high',
                delay: 100
            });
        },

        // Form success messages
        formSuccess(message) {
            queueAnnouncement('form', message, {
                priority: 'normal',
                delay: 100
            });
        },

        // Generic high-priority announcements (errors, critical state changes)
        critical(message) {
            queueAnnouncement('system', message, { priority: 'high' });
        },

        // Status updates (dashboard stats changes)
        statusUpdate(type, value, unit = '') {
            let message = '';

            switch (type) {
                case 'uptime':
                    message = `Stream uptime: ${value}`;
                    break;
                case 'quality':
                    message = `Stream quality: ${value}`;
                    break;
                case 'buffer':
                    const bufferPercent = Math.round(value * 100);
                    message = `Buffer ${bufferPercent}%`;
                    break;
                default:
                    if (unit) {
                        message = `${type}: ${value} ${unit}`;
                    } else {
                        message = `${type}: ${value}`;
                    }
            }

            if (message) {
                // Use activity region for status updates
                queueAnnouncement('activity', message, {
                    priority: 'low',
                    delay: 500
                });
            }
        }
    };

    // Public API
    window.ScreenReader = {
        ...announcements,
        initialize: initializeAnnouncements,
        queueAnnouncement: queueAnnouncement,
        announce: announce // Direct announce function for special cases
    };

    // Initialize when DOM is ready
    document.addEventListener('DOMContentLoaded', function() {
        // Small delay to ensure DOM is fully ready
        setTimeout(initializeAnnouncements, 100);
    });

    AppLogger.log('Screen reader announcements module loaded');

})();