using FluentAssertions;
using NUnit.Framework;
using System;
using System.Collections.Generic;
using System.IO;
using System.Threading.Tasks;
using CliFx.Services;
using CliFx.Tests.Stubs;
using CliFx.Tests.TestCommands;

namespace CliFx.Tests
{
    [TestFixture]
    public class CliApplicationTests
    {
        private const string TestVersionText = "v1.0";

        private static IEnumerable<TestCaseData> GetTestCases_RunAsync()
        {
            yield return new TestCaseData(
                new[] { typeof(HelloWorldDefaultCommand) },
                new string[0],
                "Hello world."
            );

            yield return new TestCaseData(
                new[] { typeof(ConcatCommand) },
                new[] { "concat", "-i", "foo", "-i", "bar", "-s", " " },
                "foo bar"
            );

            yield return new TestCaseData(
                new[] { typeof(ConcatCommand) },
                new[] { "concat", "-i", "one", "two", "three", "-s", ", " },
                "one, two, three"
            );

            yield return new TestCaseData(
                new[] { typeof(DivideCommand) },
                new[] { "div", "-D", "24", "-d", "8" },
                "3"
            );

            yield return new TestCaseData(
                new[] { typeof(HelloWorldDefaultCommand) },
                new[] { "--version" },
                TestVersionText
            );

            yield return new TestCaseData(
                new[] { typeof(ConcatCommand) },
                new[] { "--version" },
                TestVersionText
            );

            yield return new TestCaseData(
                new[] { typeof(HelloWorldDefaultCommand) },
                new[] { "-h" },
                null
            );

            yield return new TestCaseData(
                new[] { typeof(HelloWorldDefaultCommand) },
                new[] { "--help" },
                null
            );

            yield return new TestCaseData(
                new[] { typeof(ConcatCommand) },
                new string[0],
                null
            );

            yield return new TestCaseData(
                new[] { typeof(ConcatCommand) },
                new[] { "-h" },
                null
            );

            yield return new TestCaseData(
                new[] { typeof(ConcatCommand) },
                new[] { "--help" },
                null
            );

            yield return new TestCaseData(
                new[] { typeof(ConcatCommand) },
                new[] { "concat", "-h" },
                null
            );

            yield return new TestCaseData(
                new[] { typeof(ExceptionCommand) },
                new[] { "exc", "-h" },
                null
            );

            yield return new TestCaseData(
                new[] { typeof(CommandExceptionCommand) },
                new[] { "exc", "-h" },
                null
            );

            yield return new TestCaseData(
                new[] { typeof(ConcatCommand) },
                new[] { "[preview]" },
                null
            );

            yield return new TestCaseData(
                new[] { typeof(ExceptionCommand) },
                new[] { "exc", "[preview]" },
                null
            );

            yield return new TestCaseData(
                new[] { typeof(ConcatCommand) },
                new[] { "concat", "[preview]", "-o", "value" },
                null
            );
        }

        private static IEnumerable<TestCaseData> GetTestCases_RunAsync_Negative()
        {
            yield return new TestCaseData(
                new Type[0],
                new string[0],
                null, null
            );

            yield return new TestCaseData(
                new[] { typeof(ConcatCommand) },
                new[] { "non-existing" },
                null, null
            );

            yield return new TestCaseData(
                new[] { typeof(ExceptionCommand) },
                new[] { "exc" },
                null, null
            );

            yield return new TestCaseData(
                new[] { typeof(CommandExceptionCommand) },
                new[] { "exc" },
                null, null
            );

            yield return new TestCaseData(
                new[] { typeof(CommandExceptionCommand) },
                new[] { "exc" },
                null, null
            );

            yield return new TestCaseData(
                new[] { typeof(CommandExceptionCommand) },
                new[] { "exc", "-m", "foo bar" },
                "foo bar", null
            );

            yield return new TestCaseData(
                new[] { typeof(CommandExceptionCommand) },
                new[] { "exc", "-m", "foo bar", "-c", "666" },
                "foo bar", 666
            );
        }

        [Test]
        [TestCaseSource(nameof(GetTestCases_RunAsync))]
        public async Task RunAsync_Test(IReadOnlyList<Type> commandTypes, IReadOnlyList<string> commandLineArguments,
            string expectedStdOut = null)
        {
            // Arrange
            using (var stdoutStream = new StringWriter())
            {
                var console = new VirtualConsole(stdoutStream);
                var environmentVariablesProvider = new EnvironmentVariablesProviderStub();

                var application = new CliApplicationBuilder()
                    .AddCommands(commandTypes)
                    .UseVersionText(TestVersionText)
                    .UseConsole(console)
                    .UseEnvironmentVariablesProvider(environmentVariablesProvider)
                    .Build();

                // Act
                var exitCode = await application.RunAsync(commandLineArguments);
                var stdOut = stdoutStream.ToString().Trim();

                // Assert
                exitCode.Should().Be(0);

                if (expectedStdOut != null)
                    stdOut.Should().Be(expectedStdOut);
                else
                    stdOut.Should().NotBeNullOrWhiteSpace();
            }
        }

        [Test]
        [TestCaseSource(nameof(GetTestCases_RunAsync_Negative))]
        public async Task RunAsync_Negative_Test(IReadOnlyList<Type> commandTypes, IReadOnlyList<string> commandLineArguments,
            string expectedStdErr = null, int? expectedExitCode = null)
        {
            // Arrange
            using (var stderrStream = new StringWriter())
            {
                var console = new VirtualConsole(TextWriter.Null, stderrStream);
                var environmentVariablesProvider = new EnvironmentVariablesProviderStub();

                var application = new CliApplicationBuilder()
                    .AddCommands(commandTypes)
                    .UseVersionText(TestVersionText)
                    .UseEnvironmentVariablesProvider(environmentVariablesProvider)
                    .UseConsole(console)
                    .Build();

                // Act
                var exitCode = await application.RunAsync(commandLineArguments);
                var stderr = stderrStream.ToString().Trim();

                // Assert
                if (expectedExitCode != null)
                    exitCode.Should().Be(expectedExitCode);
                else
                    exitCode.Should().NotBe(0);

                if (expectedStdErr != null)
                    stderr.Should().Be(expectedStdErr);
                else
                    stderr.Should().NotBeNullOrWhiteSpace();
            }
        }

        [Test]
        public async Task RunAsync_Cancellation_Test()
        {
            // Arrange
            using (var stdoutStream = new StringWriter())
            {
                var console = new VirtualConsole(stdoutStream);
                
                var application = new CliApplicationBuilder()
                    .AddCommand(typeof(CancellableCommand))
                    .UseConsole(console)
                    .Build();
                var args = new[] { "cancel" };

                // Act
                var runTask = application.RunAsync(args);
                console.Cancel();
                var exitCode = await runTask.ConfigureAwait(false);
                var stdOut = stdoutStream.ToString().Trim();

                // Assert
                exitCode.Should().Be(-2146233029);
                stdOut.Should().Be("Printed");
            }
        }
    }
}