js/persistence.js

/**
 * Adaptive Tactics - Persistence Layer
 * Handles localStorage with graceful fallback to in-memory storage
 */

// In-memory fallback storage
const memoryStorage = new Map();

// Check if localStorage is available
let storageAvailable = false;
try {
    const testKey = '__at_test__';
    localStorage.setItem(testKey, testKey);
    localStorage.removeItem(testKey);
    storageAvailable = true;
} catch (e) {
    console.warn('localStorage not available, using in-memory storage');
    storageAvailable = false;
}

/**
 * Save data to storage
 * @param {string} key - Storage key
 * @param {any} data - Data to store (will be JSON serialized)
 * @returns {boolean} Success status
 */
export function save(key, data) {
    try {
        const serialized = JSON.stringify(data);
        if (storageAvailable) {
            localStorage.setItem(key, serialized);
        } else {
            memoryStorage.set(key, serialized);
        }
        return true;
    } catch (e) {
        console.error(`Failed to save data for key "${key}":`, e);
        return false;
    }
}

/**
 * Load data from storage
 * @param {string} key - Storage key
 * @returns {any|null} Parsed data or null if not found
 */
export function load(key) {
    try {
        let serialized;
        if (storageAvailable) {
            serialized = localStorage.getItem(key);
        } else {
            serialized = memoryStorage.get(key);
        }
        if (serialized === null || serialized === undefined) {
            return null;
        }
        return JSON.parse(serialized);
    } catch (e) {
        console.error(`Failed to load data for key "${key}":`, e);
        return null;
    }
}

/**
 * Remove data from storage
 * @param {string} key - Storage key
 * @returns {boolean} Success status
 */
export function remove(key) {
    try {
        if (storageAvailable) {
            localStorage.removeItem(key);
        } else {
            memoryStorage.delete(key);
        }
        return true;
    } catch (e) {
        console.error(`Failed to remove data for key "${key}":`, e);
        return false;
    }
}

/**
 * Clear all game-related storage
 * @returns {boolean} Success status
 */
export function clearAll() {
    try {
        if (storageAvailable) {
            // Only clear our keys, not all localStorage
            const keysToRemove = [];
            for (let i = 0; i < localStorage.length; i++) {
                const key = localStorage.key(i);
                if (key && key.startsWith('at_')) {
                    keysToRemove.push(key);
                }
            }
            keysToRemove.forEach(key => localStorage.removeItem(key));
        } else {
            memoryStorage.clear();
        }
        return true;
    } catch (e) {
        console.error('Failed to clear storage:', e);
        return false;
    }
}

/**
 * Check if storage is persistent (localStorage) or temporary (memory)
 * @returns {boolean} True if using localStorage
 */
export function isPersistent() {
    return storageAvailable;
}