/**
 * Shared utility functions for the Great Lakes Ice Report frontend
 */

/**
 * Helper function to parse UTC date consistently across all frontend scripts
 * Ensures timestamp is treated as UTC if it doesn't have timezone info
 * @param {string} timestamp - The timestamp string to parse
 * @returns {Date} - Parsed Date object with proper UTC interpretation
 */
const parseUTCDate = (timestamp) => {
    return new Date(timestamp.includes('T') ? timestamp : timestamp + 'Z');
};

/**
 * Calculate human-readable time ago string
 * @param {string} timestamp - The timestamp to calculate from
 * @returns {string} - Human-readable time difference
 */
const getTimeAgo = (timestamp) => {
    const now = new Date();
    const reportTime = parseUTCDate(timestamp);
    const diffInMinutes = Math.floor((now - reportTime) / (1000 * 60));
    
    if (diffInMinutes < 1) return 'just now';
    if (diffInMinutes < 60) return `${diffInMinutes} minute${diffInMinutes !== 1 ? 's' : ''} ago`;
    
    const diffInHours = Math.floor(diffInMinutes / 60);
    if (diffInHours < 24) return `${diffInHours} hour${diffInHours !== 1 ? 's' : ''} ago`;
    
    const diffInDays = Math.floor(diffInHours / 24);
    if (diffInDays < 7) return `${diffInDays} day${diffInDays !== 1 ? 's' : ''} ago`;
    
    return reportTime.toLocaleDateString();
};

/**
 * Calculate time remaining until 48-hour expiration
 * @param {string} timestamp - The creation timestamp
 * @param {boolean} persistent - Whether the report is persistent
 * @returns {string} - Time remaining string
 */
const getTimeRemaining = (timestamp, persistent = false) => {
    if (persistent) {
        return 'Persistent';
    }
    
    const now = new Date();
    const reportTime = parseUTCDate(timestamp);
    const expirationTime = new Date(reportTime.getTime() + 48 * 60 * 60 * 1000);
    const remaining = expirationTime - now;
    
    if (remaining <= 0) return 'Expired';
    
    const hours = Math.floor(remaining / (1000 * 60 * 60));
    const minutes = Math.floor((remaining % (1000 * 60 * 60)) / (1000 * 60));
    
    if (hours > 0) {
        return `${hours}h ${minutes}m`;
    } else {
        return `${minutes}m`;
    }
};

/**
 * Get CSS class for time remaining styling
 * @param {string} timestamp - The creation timestamp
 * @param {boolean} persistent - Whether the report is persistent
 * @returns {string} - CSS class name
 */
const getRemainingClass = (timestamp, persistent = false) => {
    if (persistent) {
        return 'normal'; // Use normal styling for persistent reports
    }
    
    const now = new Date();
    const reportTime = parseUTCDate(timestamp);
    const expirationTime = new Date(reportTime.getTime() + 48 * 60 * 60 * 1000);
    const remaining = expirationTime - now;
    const hoursRemaining = remaining / (1000 * 60 * 60);
    
    if (hoursRemaining <= 1) return 'urgent';
    if (hoursRemaining <= 6) return 'warning';
    return 'normal';
};

// Export functions for module usage (if using ES6 modules in the future)
// For now, functions are available globally when script is included
if (typeof module !== 'undefined' && module.exports) {
    module.exports = {
        parseUTCDate,
        getTimeAgo,
        getTimeRemaining,
        getRemainingClass
    };
}