using Invercargill;
using Invercargill.DataStructures;
using Json;

namespace Spry.Authentication {

    /**
     * User represents an authenticated user and implements the Identity interface
     * for integration with the Authorisation system.
     */
    public class User : GLib.Object, Authorisation.Identity {

        // =========================================================================
        // Identity Properties (required by Authorisation.Identity interface)
        // =========================================================================

        // Backing fields for identity properties
        private string _id = "";
        private string _username = "";

        /**
         * Unique identifier for this user.
         * Read-only for Identity interface compliance.
         * Use set_id() to modify.
         */
        public string id {
            get { return _id; }
        }

        /**
         * Human-readable name for this user.
         * Read-only for Identity interface compliance.
         * Use set_username() to modify.
         */
        public string username {
            get { return _username; }
        }

        /**
         * Returns permissions as an array for the Identity interface.
         * Converts from internal Vector<string> to string[] for serialization.
         */
        public string[] permissions {
            owned get {
                var result = new string[0];
                foreach (var perm in _permissions) {
                    result += perm;
                }
                return result;
            }
        }

        /**
         * Returns user data as a Variant for embedding in authorisation tokens.
         * Includes email, app_data, and timestamps.
         */
        public Variant data {
            owned get {
                return get_data_variant();
            }
        }

        // =========================================================================
        // Additional Authentication Data
        // =========================================================================

        public string email { get; set; }
        public string password_hash { get; set; }

        // Metadata
        public DateTime created_at { get; set; }
        public DateTime? updated_at { get; set; }

        // Application-specific data - stored as JSON object
        public Dictionary<string, string> app_data { get; set; default = new Dictionary<string, string>(); }

        // =========================================================================
        // Internal Storage
        // =========================================================================

        // Internal vector storage for permissions (used for mutability)
        private Vector<string> _permissions = new Vector<string>();

        // =========================================================================
        // Setters for Identity Properties
        // =========================================================================

        /**
         * Sets the user ID.
         */
        public void set_id(string value) {
            _id = value;
        }

        /**
         * Sets the username.
         */
        public void set_username(string value) {
            _username = value;
        }

        // =========================================================================
        // Permission Management (for internal use)
        // =========================================================================

        /**
         * Gets the internal permissions vector for mutation.
         * Used by PermissionService to add/remove permissions.
         */
        public Vector<string> get_permissions_vector() {
            return _permissions;
        }

        /**
         * Adds a permission to the user.
         */
        public void add_permission(string permission) {
            _permissions.add(permission);
        }

        /**
         * Removes a permission from the user.
         */
        public void remove_permission(string permission) {
            _permissions.remove(permission);
        }

        /**
         * Clears all permissions from the user.
         */
        public void clear_permissions() {
            _permissions.clear();
        }

        /**
         * Checks if the user has a specific permission.
         */
        public bool has_permission(string permission) {
            foreach (var perm in _permissions) {
                if (perm == permission) {
                    return true;
                }
            }
            return false;
        }

        // =========================================================================
        // Helper Methods
        // =========================================================================

        /**
         * Helper to convert user data to Variant for token embedding.
         */
        private Variant get_data_variant() {
            var builder = new VariantBuilder(VariantType.VARDICT);
            
            builder.add("{sv}", "email", new Variant.string(email ?? ""));
            builder.add("{sv}", "created_at", new Variant.string(created_at != null ? created_at.format_iso8601() : ""));
            
            if (updated_at != null) {
                builder.add("{sv}", "updated_at", new Variant.string(((!)updated_at).format_iso8601()));
            }
            
            // Add app_data as a dictionary
            var app_data_builder = new VariantBuilder(VariantType.VARDICT);
            var iter = app_data.iterator();
            while (iter.next()) {
                var pair = iter.get();
                app_data_builder.add("{sv}", pair.key, new Variant.string(pair.value ?? ""));
            }
            builder.add("{sv}", "app_data", app_data_builder.end());
            
            return builder.end();
        }

        // =========================================================================
        // Constructors and JSON Serialization
        // =========================================================================

        public User() {
            _id = "";
            _username = "";
            email = "";
            password_hash = "";
            created_at = new DateTime.now_utc();
        }

        public static User from_json(Json.Object obj) {
            var user = new User();

            // Required string fields - use has_member and null coalescing for safety
            user.set_id(obj.has_member("id") ? (obj.get_string_member("id") ?? "") : "");
            user.set_username(obj.has_member("username") ? (obj.get_string_member("username") ?? "") : "");
            user.email = obj.has_member("email") ? (obj.get_string_member("email") ?? "") : "";
            user.password_hash = obj.has_member("password_hash") ? (obj.get_string_member("password_hash") ?? "") : "";

            // created_at - check member exists and value is not null/empty
            if (obj.has_member("created_at")) {
                var created_str = obj.get_string_member("created_at");
                if (created_str != null && created_str.length > 0) {
                    user.created_at = new DateTime.from_iso8601(created_str, new TimeZone.utc());
                }
            }

            // updated_at (optional) - check member exists, is not null, and has value
            if (obj.has_member("updated_at")) {
                var member = obj.get_member("updated_at");
                if (member != null && member.get_node_type() == Json.NodeType.VALUE) {
                    var updated_str = obj.get_string_member("updated_at");
                    if (updated_str != null && updated_str.length > 0) {
                        user.updated_at = new DateTime.from_iso8601(updated_str, new TimeZone.utc());
                    }
                }
            }

            // permissions (array of strings) - check member exists and is array
            if (obj.has_member("permissions")) {
                var member = obj.get_member("permissions");
                if (member != null && member.get_node_type() == Json.NodeType.ARRAY) {
                    var perms_array = obj.get_array_member("permissions");
                    if (perms_array != null) {
                        foreach (var perm in perms_array.get_elements()) {
                            var perm_str = perm.get_string();
                            if (perm_str != null) {
                                user._permissions.add(perm_str);
                            }
                        }
                    }
                }
            }

            // app_data (object with string values) - check member exists and is object
            if (obj.has_member("app_data")) {
                var member = obj.get_member("app_data");
                if (member != null && member.get_node_type() == Json.NodeType.OBJECT) {
                    var app_data_obj = obj.get_object_member("app_data");
                    if (app_data_obj != null) {
                        foreach (var key in app_data_obj.get_members()) {
                            var value = app_data_obj.get_string_member(key);
                            user.app_data.set(key, value ?? "");
                        }
                    }
                }
            }

            return user;
        }

        public Json.Object to_json() {
            var obj = new Json.Object();

            // Use null coalescing to ensure we never pass null to set_string_member
            obj.set_string_member("id", id ?? "");
            obj.set_string_member("username", username ?? "");
            obj.set_string_member("email", email ?? "");
            obj.set_string_member("password_hash", password_hash ?? "");
            obj.set_string_member("created_at", created_at != null ? created_at.format_iso8601() : new DateTime.now_utc().format_iso8601());

            // updated_at (optional)
            if (updated_at != null) {
                obj.set_string_member("updated_at", ((!)updated_at).format_iso8601());
            } else {
                obj.set_null_member("updated_at");
            }

            // permissions array - always create array even if empty
            var perms_array = new Json.Array();
            if (_permissions != null) {
                foreach (var perm in _permissions) {
                    if (perm != null) {
                        perms_array.add_string_element(perm);
                    }
                }
            }
            obj.set_array_member("permissions", perms_array);

            // app_data object - always create object even if empty
            var app_data_obj = new Json.Object();
            if (app_data != null) {
                var iter = app_data.iterator();
                while (iter.next()) {
                    var pair = iter.get();
                    app_data_obj.set_string_member(pair.key ?? "", pair.value ?? "");
                }
            }
            obj.set_object_member("app_data", app_data_obj);

            return obj;
        }
    }
}