/**
 * PersistenceManager Module
 * Handles saving and loading the game state.
 */
export class PersistenceManager {
    /**
     * Create a new PersistenceManager
     * @param {Object} config - Configuration options
     * @param {Storage} config.storage - The storage backend (e.g., localStorage)
     * @param {string} config.saveStateKey - Key for saving the state
     * @param {string} config.saveHistoryKey - Key for saving the history
     */
    constructor(config = {}) {
        this.storage = config.storage || window.localStorage;
        this.saveStateKey = config.saveStateKey || 'save-state';
        this.saveHistoryKey = config.saveHistoryKey || 'save-history';
    }

    /**
     * Save the current state
     * @param {Object} stateObject - The state object to save
     * @param {string} stateObject.inkJson - The serialized Ink state
     * @param {Array<string>} stateObject.history - Array of HTML strings representing the story history
     * @returns {boolean} Whether the save was successful
     */
    saveState(stateObject) {
        try {
            if (stateObject.inkJson) {
                this.storage.setItem(this.saveStateKey, stateObject.inkJson);
            }
            
            if (stateObject.history) {
                this.storage.setItem(this.saveHistoryKey, JSON.stringify(stateObject.history));
            }
            
            return true;
        } catch (error) {
            console.error('Error saving state:', error);
            return false;
        }
    }

    /**
     * Load the saved state
     * @returns {Object|null} The loaded state object or null if no save exists
     */
    loadState() {
        try {
            const inkJson = this.storage.getItem(this.saveStateKey);
            const historyJson = this.storage.getItem(this.saveHistoryKey);
            
            if (!inkJson && !historyJson) {
                return null;
            }
            
            const result = {};
            
            if (inkJson) {
                result.inkJson = inkJson;
            }
            
            if (historyJson) {
                result.history = JSON.parse(historyJson);
            }
            
            return result;
        } catch (error) {
            console.error('Error loading state:', error);
            return null;
        }
    }

    /**
     * Check if a saved state exists
     * @returns {boolean} Whether a saved state exists
     */
    hasSavedState() {
        return this.storage.getItem(this.saveStateKey) !== null;
    }

    /**
     * Delete the saved state
     * @returns {boolean} Whether the deletion was successful
     */
    deleteSavedState() {
        try {
            this.storage.removeItem(this.saveStateKey);
            this.storage.removeItem(this.saveHistoryKey);
            return true;
        } catch (error) {
            console.error('Error deleting saved state:', error);
            return false;
        }
    }

    /**
     * Export the saved state as a JSON string
     * @returns {string|null} The exported state as a JSON string or null if no save exists
     */
    exportState() {
        const state = this.loadState();
        if (!state) {
            return null;
        }
        
        return JSON.stringify(state);
    }

    /**
     * Import a state from a JSON string
     * @param {string} jsonString - The JSON string to import
     * @returns {boolean} Whether the import was successful
     */
    importState(jsonString) {
        try {
            const state = JSON.parse(jsonString);
            return this.saveState(state);
        } catch (error) {
            console.error('Error importing state:', error);
            return false;
        }
    }
}