/* ========================================================================
 * Copyright (c) 2005-2025 The OPC Foundation, Inc. All rights reserved.
 *
 * OPC Foundation MIT License 1.00
 *
 * Permission is hereby granted, free of charge, to any person
 * obtaining a copy of this software and associated documentation
 * files (the "Software"), to deal in the Software without
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 * copies of the Software, and to permit persons to whom the
 * Software is furnished to do so, subject to the following
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 *
 * The above copyright notice and this permission notice shall be
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 * OTHER DEALINGS IN THE SOFTWARE.
 *
 * The complete license agreement can be found here:
 * http://opcfoundation.org/License/MIT/1.00/
 * ======================================================================*/

using System;
using System.Collections.Generic;
using System.Reflection;
using Moq;
using NUnit.Framework;

namespace Opc.Ua.SourceGeneration.Generator.Tests
{
    /// <summary>
    /// Unit tests for the Generators.GenerateCode method
    /// </summary>
    [TestFixture]
    [Category("Api")]
    [SetCulture("en-us")]
    [SetUICulture("en-us")]
    [Parallelizable]
    public class GeneratorsTests
    {
        /// <summary>
        /// Regression: when the target's Namespaces constant name collides with
        /// another namespace, a new name is built from the prefix. Keyword parts
        /// were escaped with '@' before being concatenated, which put the '@' in
        /// the middle of the identifier ("Acme@base@object").
        /// </summary>
        [TestCase("acme.base.object", "AcmeBaseObject")]
        [TestCase("Acme.Class", "AcmeClass")]
        [TestCase("2024.models", "_2024Models")]
        public void UniqueTargetNamespaceNameIsAValidIdentifier(string prefix, string expected)
        {
            var target = new Opc.Ua.Schema.Model.Namespace
            {
                Name = "Base",
                Prefix = prefix,
                Value = "urn:test:target"
            };
            var other = new Opc.Ua.Schema.Model.Namespace
            {
                Name = "Base",
                Prefix = "Other",
                Value = "urn:test:other"
            };
            var design = new Mock<Opc.Ua.Schema.Model.IModelDesign>();
            design.SetupGet(d => d.TargetNamespace).Returns(target);
            design.SetupGet(d => d.Namespaces).Returns([target, other]);

            Generators.EnsureUniqueTargetNamespaceName(design.Object);

            Assert.That(target.Name, Is.EqualTo(expected));
        }

        /// <summary>
        /// Tests that GenerateCode returns early when DesignFiles collection is empty.
        /// Input: Empty DesignFiles collection
        /// Expected: Method returns without processing, no file system or telemetry calls
        /// </summary>
        [Test]
        public void GenerateCode_EmptyDesignFilesCollection_ReturnsEarlyWithoutProcessing()
        {
            // Arrange
            var designFiles = new DesignFileCollection
            {
                Targets = []
            };
            var mockFileSystem = new Mock<IFileSystem>(MockBehavior.Strict);
            var mockTelemetry = new Mock<ITelemetryContext>(MockBehavior.Strict);
            const string outputDir = "output";

            // Act
            designFiles.GenerateCode(mockFileSystem.Object, outputDir, mockTelemetry.Object);

            // Assert - No calls should be made to mocks (MockBehavior.Strict would throw if they were)
            mockFileSystem.VerifyNoOtherCalls();
            mockTelemetry.VerifyNoOtherCalls();
        }

        /// <summary>
        /// Tests that GenerateCode returns early when the nodesets Files collection is empty.
        /// Condition: nodesets.Files.Count == 0
        /// Expected: Method returns immediately without processing
        /// </summary>
        [Test]
        public void GenerateCode_EmptyFilesCollection_ReturnsEarly()
        {
            // Arrange
            var mockFileSystem = new Mock<IFileSystem>();
            var mockTelemetry = new Mock<ITelemetryContext>();
            var nodesets = new NodesetFileCollection(
                [],
                [],
                mockFileSystem.Object,
                mockTelemetry.Object);

            // Act
            nodesets.GenerateCode(
                mockFileSystem.Object,
                "output",
                mockTelemetry.Object);

            // Assert
            Assert.That(nodesets.Files, Is.Empty);
        }

        /// <summary>
        /// Tests that GenerateCode handles null outputDir parameter.
        /// Condition: outputDir is null
        /// Expected: Method executes without throwing exception
        /// </summary>
        [Test]
        public void GenerateCode_NullOutputDir_DoesNotThrow()
        {
            // Arrange
            var mockFileSystem = new Mock<IFileSystem>();
            var mockTelemetry = new Mock<ITelemetryContext>();
            var nodesets = new NodesetFileCollection(
                [],
                [],
                mockFileSystem.Object,
                mockTelemetry.Object);

            // Act & Assert
            Assert.DoesNotThrow(() => nodesets.GenerateCode(
                mockFileSystem.Object,
                null!,
                mockTelemetry.Object));
        }

        /// <summary>
        /// Tests that GenerateCode handles empty string outputDir parameter.
        /// Condition: outputDir is empty string
        /// Expected: Method executes without throwing exception
        /// </summary>
        [Test]
        public void GenerateCode_EmptyOutputDir_DoesNotThrow()
        {
            // Arrange
            var mockFileSystem = new Mock<IFileSystem>();
            var mockTelemetry = new Mock<ITelemetryContext>();
            var nodesets = new NodesetFileCollection(
                [],
                [],
                mockFileSystem.Object,
                mockTelemetry.Object);

            // Act & Assert
            Assert.DoesNotThrow(() => nodesets.GenerateCode(
                mockFileSystem.Object,
                string.Empty,
                mockTelemetry.Object));
        }

        /// <summary>
        /// Tests that GenerateCode handles whitespace outputDir parameter.
        /// Condition: outputDir contains only whitespace
        /// Expected: Method executes without throwing exception
        /// </summary>
        [Test]
        public void GenerateCode_WhitespaceOutputDir_DoesNotThrow()
        {
            // Arrange
            var mockFileSystem = new Mock<IFileSystem>();
            var mockTelemetry = new Mock<ITelemetryContext>();
            var nodesets = new NodesetFileCollection(
                [],
                [],
                mockFileSystem.Object,
                mockTelemetry.Object);

            // Act & Assert
            Assert.DoesNotThrow(() => nodesets.GenerateCode(
                mockFileSystem.Object,
                "   ",
                mockTelemetry.Object));
        }

        /// <summary>
        /// Tests that GenerateCode handles outputDir with special characters.
        /// Condition: outputDir contains special characters
        /// Expected: Method executes without throwing exception
        /// </summary>
        [Test]
        public void GenerateCode_OutputDirWithSpecialCharacters_DoesNotThrow()
        {
            // Arrange
            var mockFileSystem = new Mock<IFileSystem>();
            var mockTelemetry = new Mock<ITelemetryContext>();
            var nodesets = new NodesetFileCollection(
                [],
                [],
                mockFileSystem.Object,
                mockTelemetry.Object);

            // Act & Assert
            Assert.DoesNotThrow(() => nodesets.GenerateCode(
                mockFileSystem.Object,
                "C:\\Special@#$%Folder\\Output",
                mockTelemetry.Object));
        }

        /// <summary>
        /// Tests that GenerateCode handles null options parameter by creating default options.
        /// Condition: options parameter is null
        /// Expected: Method creates new GeneratorOptions instance internally
        /// </summary>
        [Test]
        public void GenerateCode_NullOptions_DoesNotThrow()
        {
            // Arrange
            var mockFileSystem = new Mock<IFileSystem>();
            var mockTelemetry = new Mock<ITelemetryContext>();
            var nodesets = new NodesetFileCollection(
                [],
                [],
                mockFileSystem.Object,
                mockTelemetry.Object);

            // Act & Assert
            Assert.DoesNotThrow(() => nodesets.GenerateCode(
                mockFileSystem.Object,
                "output",
                mockTelemetry.Object,
                options: null!));
        }

        /// <summary>
        /// Tests that GenerateCode uses provided options when not null.
        /// Condition: options parameter is provided
        /// Expected: Method uses the provided options
        /// </summary>
        [Test]
        public void GenerateCode_WithOptions_DoesNotThrow()
        {
            // Arrange
            var mockFileSystem = new Mock<IFileSystem>();
            var mockTelemetry = new Mock<ITelemetryContext>();
            var nodesets = new NodesetFileCollection(
                [],
                [],
                mockFileSystem.Object,
                mockTelemetry.Object);
            var options = new GeneratorOptions();

            // Act & Assert
            Assert.DoesNotThrow(() => nodesets.GenerateCode(
                mockFileSystem.Object,
                "output",
                mockTelemetry.Object,
                options: options));
        }

        /// <summary>
        /// Tests that GenerateCode handles useAllowSubtypes set to false.
        /// Condition: useAllowSubtypes is false
        /// Expected: Method executes with useAllowSubtypes false
        /// </summary>
        [Test]
        public void GenerateCode_UseAllowSubtypesFalse_DoesNotThrow()
        {
            // Arrange
            var mockFileSystem = new Mock<IFileSystem>();
            var mockTelemetry = new Mock<ITelemetryContext>();
            var nodesets = new NodesetFileCollection(
                [],
                [],
                mockFileSystem.Object,
                mockTelemetry.Object);

            // Act & Assert
            Assert.DoesNotThrow(() => nodesets.GenerateCode(
                mockFileSystem.Object,
                "output",
                mockTelemetry.Object,
                useAllowSubtypes: false));
        }

        /// <summary>
        /// Tests that GenerateCode handles useAllowSubtypes set to true.
        /// Condition: useAllowSubtypes is true
        /// Expected: Method executes with useAllowSubtypes true
        /// </summary>
        [Test]
        public void GenerateCode_UseAllowSubtypesTrue_DoesNotThrow()
        {
            // Arrange
            var mockFileSystem = new Mock<IFileSystem>();
            var mockTelemetry = new Mock<ITelemetryContext>();
            var nodesets = new NodesetFileCollection(
                [],
                [],
                mockFileSystem.Object,
                mockTelemetry.Object);

            // Act & Assert
            Assert.DoesNotThrow(() => nodesets.GenerateCode(
                mockFileSystem.Object,
                "output",
                mockTelemetry.Object,
                useAllowSubtypes: true));
        }

        /// <summary>
        /// Tests that GenerateCode handles all boolean parameter combinations.
        /// </summary>
        [Theory]
        public void GenerateCode_BooleanParameterCombinations_DoesNotThrow(
            bool useAllowSubtypes)
        {
            // Arrange
            var mockFileSystem = new Mock<IFileSystem>();
            var mockTelemetry = new Mock<ITelemetryContext>();
            var nodesets = new NodesetFileCollection(
                [],
                [],
                mockFileSystem.Object,
                mockTelemetry.Object);

            // Act & Assert
            Assert.DoesNotThrow(() => nodesets.GenerateCode(
                mockFileSystem.Object,
                "output",
                mockTelemetry.Object,
                useAllowSubtypes: useAllowSubtypes));
        }

        /// <summary>
        /// Verifies that the original public GenerateCode signatures remain available.
        /// </summary>
        [Test]
        public void GenerateCodeOriginalPublicSignaturesArePreserved()
        {
            AssertPublicGenerateCodeSignature(
            [
                typeof(DesignFileCollection),
                typeof(IFileSystem),
                typeof(string),
                typeof(ITelemetryContext),
                typeof(GeneratorOptions),
                typeof(bool),
                typeof(List<string>),
                typeof(IReadOnlyDictionary<string, ModelDependencyReference>),
                typeof(IReadOnlyList<NodeManagerAttributeBinding>),
                typeof(Action<NodeManagerAttributeBinding, string>),
                typeof(HashSet<NodeManagerAttributeBinding>),
                typeof(int)
            ]);
            AssertPublicGenerateCodeSignature(
            [
                typeof(NodesetFileCollection),
                typeof(IFileSystem),
                typeof(string),
                typeof(ITelemetryContext),
                typeof(GeneratorOptions),
                typeof(bool),
                typeof(IReadOnlyDictionary<string, ModelDependencyReference>),
                typeof(IReadOnlyList<NodeManagerAttributeBinding>),
                typeof(Action<NodeManagerAttributeBinding, string>),
                typeof(IReadOnlyDictionary<string, Dependency.ModelDependencyV1>),
                typeof(HashSet<NodeManagerAttributeBinding>),
                typeof(int)
            ]);
        }

        private static void AssertPublicGenerateCodeSignature(Type[] parameterTypes)
        {
            MethodInfo method = typeof(Generators).GetMethod(
                nameof(Generators.GenerateCode),
                parameterTypes) ?? throw new AssertionException("GenerateCode signature not found.");

            Assert.Multiple(() =>
            {
                Assert.That(method.IsPublic, Is.True);
                Assert.That(method.IsStatic, Is.True);
                Assert.That(method.ReturnType, Is.EqualTo(typeof(void)));
            });

            ParameterInfo[] parameters = method.GetParameters();
            for (int ii = 4; ii < parameters.Length; ii++)
            {
                Assert.That(
                    parameters[ii].IsOptional,
                    Is.True,
                    $"Parameter '{parameters[ii].Name}' must remain optional.");
            }
        }
    }
}