// Copyright (c) 2012-2021 Wojciech Figat. All rights reserved.

using System;
using System.Collections.Generic;
using System.Diagnostics;

#pragma warning disable 1591

namespace FlaxEngine.Assertions
{
    /// <summary>
    /// The Assert class contains assertion methods for setting invariants in the code.
    /// </summary>
    [DebuggerStepThrough]
    [HideInEditor]
    public static class Assert
    {
        /// <summary>
        /// Should an exception be thrown on a failure.
        /// </summary>
        public static bool RaiseExceptions = true;

        /// <summary>
        /// Asserts that the values are approximately equal. An absolute error check is used for approximate equality check
        /// (|a-b| &lt; tolerance). Default tolerance is 0.00001f.
        /// Note: Every time you call the method with tolerance specified, a new instance of Assertions.Comparers.FloatComparer
        /// is created. For performance reasons you might want to instance your own comparer and pass it to the AreEqual method.
        /// If the tolerance is not specifies, a default comparer is used and the issue does not occur.
        /// </summary>
        /// <param name="expected"></param>
        /// <param name="actual"></param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void AreApproximatelyEqual(float expected, float actual)
        {
            AreEqual(expected, actual, null, FloatComparer.ComparerWithDefaultTolerance);
        }

        /// <summary>
        /// Asserts that the values are approximately equal. An absolute error check is used for approximate equality check
        /// (|a-b| &lt; tolerance). Default tolerance is 0.00001f.
        /// Note: Every time you call the method with tolerance specified, a new instance of Assertions.Comparers.FloatComparer
        /// is created. For performance reasons you might want to instance your own comparer and pass it to the AreEqual method.
        /// If the tolerance is not specifies, a default comparer is used and the issue does not occur.
        /// </summary>
        /// <param name="expected"></param>
        /// <param name="actual"></param>
        /// <param name="message"></param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void AreApproximatelyEqual(float expected, float actual, string message)
        {
            AreEqual(expected, actual, message, FloatComparer.ComparerWithDefaultTolerance);
        }

        /// <summary>
        /// Asserts that the values are approximately equal. An absolute error check is used for approximate equality check
        /// (|a-b| &lt; tolerance). Default tolerance is 0.00001f.
        /// Note: Every time you call the method with tolerance specified, a new instance of Assertions.Comparers.FloatComparer
        /// is created. For performance reasons you might want to instance your own comparer and pass it to the AreEqual method.
        /// If the tolerance is not specifies, a default comparer is used and the issue does not occur.
        /// </summary>
        /// <param name="tolerance">Tolerance of approximation.</param>
        /// <param name="expected"></param>
        /// <param name="actual"></param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void AreApproximatelyEqual(float expected, float actual, float tolerance)
        {
            AreApproximatelyEqual(expected, actual, tolerance, null);
        }

        /// <summary>
        /// Asserts that the values are approximately equal. An absolute error check is used for approximate equality check
        /// (|a-b| &lt; tolerance). Default tolerance is 0.00001f.
        /// Note: Every time you call the method with tolerance specified, a new instance of Assertions.Comparers.FloatComparer
        /// is created. For performance reasons you might want to instance your own comparer and pass it to the AreEqual method.
        /// If the tolerance is not specifies, a default comparer is used and the issue does not occur.
        /// </summary>
        /// <param name="tolerance">Tolerance of approximation.</param>
        /// <param name="expected"></param>
        /// <param name="actual"></param>
        /// <param name="message"></param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void AreApproximatelyEqual(float expected, float actual, float tolerance, string message)
        {
            AreEqual(expected, actual, message, new FloatComparer(tolerance));
        }

        /// <summary>
        /// Asserts that the values are approximately equal.
        /// </summary>
        /// <typeparam name="T">The value type.</typeparam>
        /// <param name="expected">The expected value.</param>
        /// <param name="actual">The actual value.</param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void AreEqual<T>(T expected, T actual)
        {
            AreEqual(expected, actual, null);
        }

        /// <summary>
        /// Asserts that the values are approximately equal.
        /// </summary>
        /// <typeparam name="T">The value type.</typeparam>
        /// <param name="expected">The expected value.</param>
        /// <param name="actual">The actual value.</param>
        /// <param name="message">The error message.</param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void AreEqual<T>(T expected, T actual, string message)
        {
            AreEqual(expected, actual, message, EqualityComparer<T>.Default);
        }

        /// <summary>
        /// Asserts that the values are approximately equal.
        /// </summary>
        /// <typeparam name="T">The value type.</typeparam>
        /// <param name="expected">The expected value.</param>
        /// <param name="actual">The actual value.</param>
        /// <param name="message">The error message.</param>
        /// <param name="comparer">The equality comparer.</param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void AreEqual<T>(T expected, T actual, string message, IEqualityComparer<T> comparer)
        {
            if (typeof(Object).IsAssignableFrom(typeof(T)))
            {
                AreEqual((object)expected as Object, (object)actual as Object, message);
                return;
            }
            if (!comparer.Equals(actual, expected))
                Fail(GetEqualityMessage(actual, expected, true), message);
        }

        /// <summary>
        /// Asserts that the values are approximately equal.
        /// </summary>
        /// <param name="expected">The expected value.</param>
        /// <param name="actual">The actual value.</param>
        /// <param name="message">The error message.</param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void AreEqual(Object expected, Object actual, string message)
        {
            if (actual != expected)
                Fail(GetEqualityMessage(actual, expected, true), message);
        }

        /// <summary>
        /// Asserts that the values are approximately not equal. An absolute error check is used for approximate equality check
        /// (|a-b| &lt; tolerance). Default tolerance is 0.00001f.
        /// </summary>
        /// <param name="expected"></param>
        /// <param name="actual"></param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void AreNotApproximatelyEqual(float expected, float actual)
        {
            AreNotEqual(expected, actual, null, FloatComparer.ComparerWithDefaultTolerance);
        }

        /// <summary>
        /// Asserts that the values are approximately not equal. An absolute error check is used for approximate equality check
        /// (|a-b| &lt; tolerance). Default tolerance is 0.00001f.
        /// </summary>
        /// <param name="expected"></param>
        /// <param name="actual"></param>
        /// <param name="message"></param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void AreNotApproximatelyEqual(float expected, float actual, string message)
        {
            AreNotEqual(expected, actual, message, FloatComparer.ComparerWithDefaultTolerance);
        }

        /// <summary>
        /// Asserts that the values are approximately not equal. An absolute error check is used for approximate equality check
        /// (|a-b| &lt; tolerance). Default tolerance is 0.00001f.
        /// </summary>
        /// <param name="tolerance">Tolerance of approximation.</param>
        /// <param name="expected"></param>
        /// <param name="actual"></param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void AreNotApproximatelyEqual(float expected, float actual, float tolerance)
        {
            AreNotApproximatelyEqual(expected, actual, tolerance, null);
        }

        /// <summary>
        /// Asserts that the values are approximately not equal. An absolute error check is used for approximate equality check
        /// (|a-b| &lt; tolerance). Default tolerance is 0.00001f.
        /// </summary>
        /// <param name="tolerance">Tolerance of approximation.</param>
        /// <param name="expected"></param>
        /// <param name="actual"></param>
        /// <param name="message"></param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void AreNotApproximatelyEqual(float expected, float actual, float tolerance, string message)
        {
            AreNotEqual(expected, actual, message, new FloatComparer(tolerance));
        }

        [Conditional("FLAX_ASSERTIONS")]
        public static void AreNotEqual<T>(T expected, T actual)
        {
            AreNotEqual(expected, actual, null);
        }

        [Conditional("FLAX_ASSERTIONS")]
        public static void AreNotEqual<T>(T expected, T actual, string message)
        {
            AreNotEqual(expected, actual, message, EqualityComparer<T>.Default);
        }

        [Conditional("FLAX_ASSERTIONS")]
        public static void AreNotEqual<T>(T expected, T actual, string message, IEqualityComparer<T> comparer)
        {
            if (typeof(Object).IsAssignableFrom(typeof(T)))
            {
                AreNotEqual((object)expected as Object, (object)actual as Object, message);
                return;
            }
            if (comparer.Equals(actual, expected))
                Fail(GetEqualityMessage(actual, expected, false), message);
        }

        [Conditional("FLAX_ASSERTIONS")]
        public static void AreNotEqual(Object expected, Object actual, string message)
        {
            if (actual == expected)
                Fail(GetEqualityMessage(actual, expected, false), message);
        }

        public static void Fail(string message = "", string userMessage = "")
        {
            if (RaiseExceptions)
                throw new AssertionException(message, userMessage);
            if (message == null)
                message = "Assertion has failed\n";
            if (userMessage != null)
                message = string.Concat(userMessage, '\n', message);
            Debug.LogAssertion(message);
        }

        /// <summary>
        /// Asserts that the condition is false.
        /// </summary>
        /// <param name="condition"></param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void IsFalse(bool condition)
        {
            IsFalse(condition, null);
        }

        /// <summary>
        /// Asserts that the condition is false.
        /// </summary>
        /// <param name="condition"></param>
        /// <param name="message"></param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void IsFalse(bool condition, string message)
        {
            if (condition)
                Fail(BooleanFailureMessage(false), message);
        }

        [Conditional("FLAX_ASSERTIONS")]
        public static void IsNotNull<T>(T value)
        where T : class
        {
            IsNotNull(value, null);
        }

        [Conditional("FLAX_ASSERTIONS")]
        public static void IsNotNull<T>(T value, string message)
        where T : class
        {
            if (typeof(Object).IsAssignableFrom(typeof(T)))
                IsNotNull((object)value as Object, message);
            else if (value == null)
                Fail(NullFailureMessage(null, false), message);
        }

        [Conditional("FLAX_ASSERTIONS")]
        public static void IsNotNull(Object value, string message)
        {
            if (value == null)
                Fail(NullFailureMessage(null, false), message);
        }

        [Conditional("FLAX_ASSERTIONS")]
        public static void IsNull<T>(T value)
        where T : class
        {
            IsNull(value, null);
        }

        [Conditional("FLAX_ASSERTIONS")]
        public static void IsNull<T>(T value, string message)
        where T : class
        {
            if (typeof(Object).IsAssignableFrom(typeof(T)))
                IsNull((object)value as Object, message);
            else if (value != null)
                Fail(NullFailureMessage(value, true), message);
        }

        [Conditional("FLAX_ASSERTIONS")]
        public static void IsNull(Object value, string message)
        {
            if (value != null)
                Fail(NullFailureMessage(value, true), message);
        }

        /// <summary>
        /// Asserts that the condition is true.
        /// </summary>
        /// <param name="condition"></param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void IsTrue(bool condition)
        {
            IsTrue(condition, null);
        }

        /// <summary>
        /// Asserts that the condition is true.
        /// </summary>
        /// <param name="condition"></param>
        /// <param name="message"></param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void IsTrue(bool condition, string message)
        {
            if (!condition)
                Fail(BooleanFailureMessage(true), message);
        }

        /// <summary>
        /// Expect action to fail
        /// </summary>
        /// <param name="exceptionType">Type of exception to expect</param>
        /// <param name="action">Action to expect</param>
        /// <param name="message">User custom message to display</param>
        [Conditional("FLAX_ASSERTIONS")]
        public static void ExceptionExpected(Type exceptionType, Action action, string message = "")
        {
            try
            {
                action();
            }
            catch (Exception e)
            {
                if (exceptionType != e.GetType())
                {
                    Fail(GetMessage("Expected exception of type " + exceptionType.FullName + " got " + e.GetType().FullName), message);
                }
                return;
            }
            Fail(GetMessage("Expected exception of type " + exceptionType.FullName), message);
        }

        public static string BooleanFailureMessage(bool expected)
        {
            return GetMessage(string.Concat("Value was ", !expected), expected.ToString());
        }

        public static string GetEqualityMessage(object actual, object expected, bool expectEqual)
        {
            string str = string.Format("Values are {0}equal.", new object[] { !expectEqual ? string.Empty : "not " });
            object[] objArray =
            {
                actual,
                expected,
                null
            };
            objArray[2] = !expectEqual ? "!=" : "==";
            return GetMessage(str, string.Format("{0} {2} {1}", objArray));
        }

        public static string GetMessage(string failureMessage)
        {
            return string.Format("{0} {1}", new object[]
            {
                "Assertion failed.",
                failureMessage
            });
        }

        public static string GetMessage(string failureMessage, string expected)
        {
            return GetMessage($"{failureMessage}\nExpected: {expected}");
        }

        public static string NullFailureMessage(object value, bool expectNull)
        {
            return GetMessage(string.Format("Value was {0}Null", new object[] { !expectNull ? string.Empty : "not " }), string.Format("Value was {0}Null", new object[] { !expectNull ? "not " : string.Empty }));
        }
    }
}