/**
 * Authentication Manager Module
 * Handles user authentication, session management, and permissions
 */
export class AuthManager {
    constructor() {
        this.currentUser = null;
        this.authToken = null;
    }

    async checkAuthentication() {
        const token = localStorage.getItem('auth_token');
        if (!token) {
            return false;
        }
        
        try {
            const response = await fetch('/api/auth/validate', {
                headers: {
                    'Authorization': `Bearer ${token}`
                }
            });
            
            if (response.ok) {
                const data = await response.json();
                this.currentUser = data.user;
                this.authToken = token;
                return true;
            } else {
                this.clearAuthData();
                return false;
            }
        } catch (error) {
            console.error('Auth validation error:', error);
            return false;
        }
    }

    async logout() {
        try {
            await fetch('/api/auth/logout', {
                method: 'POST',
                headers: {
                    'Authorization': `Bearer ${this.authToken}`
                }
            });
        } catch (error) {
            console.error('Logout error:', error);
        } finally {
            this.clearAuthData();
            window.location.href = '/login';
        }
    }

    clearAuthData() {
        localStorage.removeItem('auth_token');
        localStorage.removeItem('user_info');
        this.currentUser = null;
        this.authToken = null;
    }

    canEditTree(createdBy) {
        if (!this.currentUser) return false;
        
        const permissions = this.currentUser.permissions || [];
        
        // Admin and system can edit any tree
        if (permissions.includes('admin') || permissions.includes('system')) {
            return true;
        }
        
        // Users can edit trees they created
        if (permissions.includes('edit_own') && createdBy === this.currentUser.username) {
            return true;
        }
        
        // Users with delete permission can edit any tree
        if (permissions.includes('delete')) {
            return true;
        }
        
        return false;
    }
    
    canDeleteTree(createdBy) {
        if (!this.currentUser) return false;
        
        const permissions = this.currentUser.permissions || [];
        
        // Only admin and system can delete trees
        if (permissions.includes('admin') || permissions.includes('system')) {
            return true;
        }
        
        // Users with explicit delete permission
        if (permissions.includes('delete')) {
            return true;
        }
        
        return false;
    }

    getAuthHeaders() {
        return {
            'Content-Type': 'application/json',
            'Authorization': `Bearer ${this.authToken}`
        };
    }
}