// Copyright (c) Microsoft Corporation. All rights reserved.
// Licensed under the MIT license. See LICENSE file in the project root for full license information.

using System;
using System.Collections.Generic;
using System.Diagnostics.CodeAnalysis;
using System.Globalization;

using Microsoft.VisualStudio.TestPlatform.Common.ExtensionFramework.Utilities;
using Microsoft.VisualStudio.TestPlatform.Common.Interfaces;
using Microsoft.VisualStudio.TestPlatform.ObjectModel;
using Microsoft.VisualStudio.TestPlatform.ObjectModel.Logging;

using CommonResources = Microsoft.VisualStudio.TestPlatform.Common.Resources.Resources;

namespace Microsoft.VisualStudio.TestPlatform.Common.ExtensionFramework;

/// <summary>
/// Generic base class for managing extensions and looking them up by their URI.
/// </summary>
/// <typeparam name="TExtension">The type of the extension.</typeparam>
/// <typeparam name="TMetadata">The type of the metadata.</typeparam>
internal abstract class TestExtensionManager<TExtension, TMetadata>
    where TMetadata : ITestExtensionCapabilities
{
    /// <summary>
    /// Used for logging errors.
    /// </summary>
    private readonly IMessageLogger _logger;

    /// <summary>
    /// Default constructor.
    /// </summary>
    /// <param name="unfilteredTestExtensions">
    /// The unfiltered Test Extensions.
    /// </param>
    /// <param name="testExtensions">
    /// The test Extensions.
    /// </param>
    /// <param name="logger">
    /// The logger.
    /// </param>
    protected TestExtensionManager(
        IEnumerable<LazyExtension<TExtension, Dictionary<string, object>>> unfilteredTestExtensions,
        IEnumerable<LazyExtension<TExtension, TMetadata>> testExtensions,
        IMessageLogger logger)
    {
        _logger = logger ?? throw new ArgumentNullException(nameof(logger));
        TestExtensions = testExtensions ?? throw new ArgumentNullException(nameof(testExtensions));
        UnfilteredTestExtensions = unfilteredTestExtensions ?? throw new ArgumentNullException(nameof(unfilteredTestExtensions));

        // Populate the map to avoid threading issues
        PopulateMap();
    }

    /// <summary>
    /// Gets unfiltered list of test extensions which are available.
    /// </summary>
    /// <remarks>
    /// When we populate the "TestExtensions" property it
    /// will filter out extensions which are missing required pieces of metadata such
    /// as the "ExtensionUri".  This field is here so we can report on extensions which
    /// are missing metadata.
    /// </remarks>
    public IEnumerable<LazyExtension<TExtension, Dictionary<string, object>>> UnfilteredTestExtensions
    {
        get; private set;
    }

    /// <summary>
    /// Gets filtered list of test extensions which are available.
    /// </summary>
    /// <remarks>
    /// When we populate the "TestExtensions" property it
    /// will filter out extensions which are missing required pieces of metadata such
    /// as the "ExtensionUri".  This field is here so we can report on extensions which
    /// are missing metadata.
    /// </remarks>
    public IEnumerable<LazyExtension<TExtension, TMetadata>> TestExtensions
    {
        get;
        private set;
    }

    /// <summary>
    /// Gets mapping between test extension URI and test extension.
    /// </summary>
    public Dictionary<Uri, LazyExtension<TExtension, TMetadata>> TestExtensionByUri
    {
        get;
        private set;
    }

    /// <summary>
    /// Looks up the test extension by its URI.
    /// </summary>
    /// <param name="extensionUri">The URI of the test extension to be looked up.</param>
    /// <returns>The test extension or null if one was not found.</returns>
    public LazyExtension<TExtension, TMetadata>? TryGetTestExtension(Uri extensionUri)
    {
        ValidateArg.NotNull(extensionUri, nameof(extensionUri));
        TestExtensionByUri.TryGetValue(extensionUri, out var testExtension);

        return testExtension;
    }

    /// <summary>
    /// Looks up the test extension by its URI (passed as a string).
    /// </summary>
    /// <param name="extensionUri">The URI of the test extension to be looked up.</param>
    /// <returns>The test extension or null if one was not found.</returns>
    public LazyExtension<TExtension, TMetadata>? TryGetTestExtension(string extensionUri)
    {
        ValidateArg.NotNull(extensionUri, nameof(extensionUri));
        LazyExtension<TExtension, TMetadata>? testExtension = null;
        foreach (var availableExtensionUri in TestExtensionByUri.Keys)
        {
            if (string.Equals(extensionUri, availableExtensionUri.AbsoluteUri, StringComparison.OrdinalIgnoreCase))
            {
                TestExtensionByUri.TryGetValue(availableExtensionUri, out testExtension);
                break;
            }
        }

        return testExtension;
    }

    /// <summary>
    /// Populate the extension map.
    /// </summary>
    [MemberNotNull(nameof(TestExtensionByUri))]
    private void PopulateMap()
    {
        TestExtensionByUri = new Dictionary<Uri, LazyExtension<TExtension, TMetadata>>();

        if (TestExtensions == null)
        {
            return;
        }

        foreach (var extension in TestExtensions)
        {
            // Convert the extension uri string to an actual uri.
            Uri? uri = null;
            try
            {
                uri = new Uri(extension.Metadata.ExtensionUri);
            }
            catch (FormatException e)
            {
                if (_logger != null)
                {
                    _logger.SendMessage(
                        TestMessageLevel.Warning,
                        string.Format(CultureInfo.CurrentCulture, CommonResources.InvalidExtensionUriFormat, extension.Metadata.ExtensionUri, e));
                }
            }

            if (uri == null)
            {
                continue;
            }

            // Make sure we are not trying to add an extension with a duplicate uri.
            if (!TestExtensionByUri.ContainsKey(uri))
            {
                TestExtensionByUri.Add(uri, extension);
            }
            else if (_logger != null)
            {
                _logger.SendMessage(
                    TestMessageLevel.Warning,
                    string.Format(CultureInfo.CurrentCulture, CommonResources.DuplicateExtensionUri, extension.Metadata.ExtensionUri));
            }
        }
    }
}