// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.

#nullable disable

using Microsoft.Build.Framework;

namespace Microsoft.AspNetCore.StaticWebAssets.Tasks;

public class ValidateStaticWebAssetsUniquePaths : Task
{
    private const string BasePath = "BasePath";
    private const string RelativePath = "RelativePath";
    private const string TargetPath = "TargetPath";

    [Required]
    public ITaskItem[] StaticWebAssets { get; set; }

    [Required]
    public ITaskItem[] WebRootFiles { get; set; }

    public override bool Execute()
    {
        var assetsByWebRootPaths = new Dictionary<string, ITaskItem>(StringComparer.OrdinalIgnoreCase);
        for (var i = 0; i < StaticWebAssets.Length; i++)
        {
            var contentRootDefinition = StaticWebAssets[i];
            if (!EnsureRequiredMetadata(contentRootDefinition, BasePath) ||
                !EnsureRequiredMetadata(contentRootDefinition, RelativePath))
            {
                return false;
            }
            else
            {
                var webRootPath = GetWebRootPath("/wwwroot",
                    contentRootDefinition.GetMetadata(BasePath),
                    contentRootDefinition.GetMetadata(RelativePath));

                if (assetsByWebRootPaths.TryGetValue(webRootPath, out var existingWebRootPath))
                {
                    if (!string.Equals(contentRootDefinition.ItemSpec, existingWebRootPath.ItemSpec, StringComparison.OrdinalIgnoreCase))
                    {
                        Log.LogError($"Conflicting assets with the same path '{webRootPath}' for content root paths '{contentRootDefinition.ItemSpec}' and '{existingWebRootPath.ItemSpec}'.");
                        return false;
                    }
                }
                else
                {
                    assetsByWebRootPaths.Add(webRootPath, contentRootDefinition);
                }
            }
        }

        for (var i = 0; i < WebRootFiles.Length; i++)
        {
            var webRootFile = WebRootFiles[i];
            var relativePath = webRootFile.GetMetadata(TargetPath);
            var webRootFileWebRootPath = GetWebRootPath("", "/", relativePath);
            if (assetsByWebRootPaths.TryGetValue(webRootFileWebRootPath, out var existingAsset))
            {
                Log.LogError($"The static web asset '{existingAsset.ItemSpec}' has a conflicting web root path '{webRootFileWebRootPath}' with the project file '{webRootFile.ItemSpec}'.");
                return false;
            }
        }

        return true;
    }

    // Normalizes /base/relative \base\relative\ base\relative and so on to /base/relative
    private static string GetWebRootPath(string webRoot, string basePath, string relativePath) => $"{webRoot}/{Path.Combine(basePath, relativePath.TrimStart('.').TrimStart('/')).Replace("\\", "/").Trim('/')}";

    private bool EnsureRequiredMetadata(ITaskItem item, string metadataName)
    {
        var value = item.GetMetadata(metadataName);
        if (string.IsNullOrEmpty(value))
        {
            Log.LogError($"Missing required metadata '{metadataName}' for '{item.ItemSpec}'.");
            return false;
        }

        return true;
    }
}