/*
 * Copyright 2019 by its authors. See AUTHORS.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
#pragma warning disable 1591

using System;
using System.Runtime.InteropServices;

namespace Eina
{

/// <summary>Error codes from native Eina methods.
/// <para>Since EFL 1.23.</para>
/// </summary>
public struct Error : IComparable<Error>
{
    int code;

    /// <summary>
    /// The error's message.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    public string Message
    {
        get { return MsgGet(this); }
    }

    /// <summary>
    /// Unhandled Exception error identifier.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    public static readonly Error UNHANDLED_EXCEPTION = eina_error_msg_register("Unhandled C# exception occurred.");

    /// <summary>
    /// No error identifier.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    public static readonly Error NO_ERROR = new Error(0);
    /// <summary>
    /// Permission error identifier.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    public static readonly Error EPERM = new Error(1);
    /// <summary>
    /// No entity error identifier.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    public static readonly Error ENOENT = new Error(2);
    /// <summary>
    /// Cancelled error identifier.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    public static readonly Error ECANCELED = new Error(125);

    /// <summary>
    /// Constructor.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    /// <param name="value">The value of the error.</param>
    public Error(int value)
    {
        code = value;
    }

    /// <summary>
    ///   Error identifier conversion from int.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    /// <param name="val">Value to be converted to Error</param>
    static public implicit operator Error(int val)
    {
        return new Error(val);
    }

    /// <summary>
    ///   Int conversion from Error.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    /// <param name="error">Error identifier to be converted to int</param>
    static public implicit operator int(Error error)
    {
        return error.code;
    }

    /// <summary>
    ///   Compare two Errors.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    /// <param name="err">Error to be compared with</param>
    /// <returns>True with the Errors is equal, False otherwise.</returns>
    public int CompareTo(Error err)
    {
        return code.CompareTo(err.code);
    }

    /// <summary>
    ///   Transform the object to a string representing the object.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    /// <returns>The string representing the value of this.</returns>
    public override string ToString()
    {
        return "Eina.Error(" + code + ")";
    }

    [DllImport(efl.Libs.Eina)] static extern Error eina_error_msg_register(string msg);
    [DllImport(efl.Libs.Eina)] static extern Error eina_error_get();
    [DllImport(efl.Libs.Eina)] static extern void eina_error_set(Error error);
    [DllImport(efl.Libs.Eina)] static extern IntPtr eina_error_msg_get(Error error);

    /// <summary>
    ///   Sets the last error.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    /// <param name="error">The error identifier.</param>
    public static void Set(Error error)
    {
        eina_error_set(error);
    }

    /// <summary>
    ///   Returns the last set error.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    /// <returns>The last error or NO_ERROR identifier.</returns>
    public static Error Get()
    {
        return eina_error_get();
    }

    /// <summary>
    ///   Returns the description of the given error identifier.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    /// <param name="error">Error identifier.</param>
    /// <returns>The description of the error.</returns>
    public static String MsgGet(Error error)
    {
        IntPtr cstr = eina_error_msg_get(error);
        return Eina.StringConversion.NativeUtf8ToManagedString(cstr);
    }

    /// <summary>Raises an exception if an unhandled exception occurred before switching
    /// back to the native code. For example, in an event handler.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    public static void RaiseIfUnhandledException()
    {
        Error e = Get();
        if (e == UNHANDLED_EXCEPTION)
        {
            Clear();
            Raise(e);
        }
    }

    /// <summary>
    ///   Raises an exception.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    public static void Raise(Error e)
    {
        if (e != 0)
        {
            throw (new Efl.EflException(MsgGet(e)));
        }
    }

    /// <summary>
    ///   Set identifier to a NO_ERROR.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    public static void Clear()
    {
        Set(0);
    }

    /// <summary>
    ///   Registers a new error type.
    /// <para>Since EFL 1.23.</para>
    /// </summary>
    /// <param name="msg"> The description of the error.</param>
    /// <returns>The unique number identifier for this error.</returns>
    public static Error Register(string msg)
    {
        return eina_error_msg_register(msg);
    }
}

}