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

using System;
using System.Collections.Generic;
using System.IO;
using System.Linq;
using Microsoft.Build.Framework;
using Microsoft.DotNet.Build.Tasks;

namespace Microsoft.DotNet.SharedFramework.Sdk
{
    public class ValidateFileVersions : BuildTask
    {
        private static readonly Version ZeroVersion = new Version(0, 0, 0, 0);

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

        public override bool Execute()
        {
            var fileVersions = new Dictionary<string, FileVersionData>(StringComparer.OrdinalIgnoreCase);
            foreach(var file in Files)
            {
                if (file.GetMetadata("IsSymbolFile").Equals("true", StringComparison.OrdinalIgnoreCase))
                {
                    continue;
                }

                var fileName = Path.GetFileName(file.ItemSpec);

                var current = GetFileVersionData(file);

                FileVersionData existing;

                if (fileVersions.TryGetValue(fileName, out existing))
                {
                    if (current.AssemblyVersion != null)
                    {
                        if (existing.AssemblyVersion == null)
                        {
                            fileVersions[fileName] = current;
                            continue;
                        }
                        else if (current.AssemblyVersion != existing.AssemblyVersion)
                        {
                            if (current.AssemblyVersion > existing.AssemblyVersion)
                            {
                                fileVersions[fileName] = current;
                            }
                            continue;
                        }
                    }

                    if (current.FileVersion != null && 
                        existing.FileVersion != null)
                    {
                        if (current.FileVersion > existing.FileVersion)
                        {
                            fileVersions[fileName] = current;
                        }
                    }
                }
                else
                {
                    fileVersions[fileName] = current;
                }
            }

            // Check for versionless files after all duplicate filenames are resolved, rather than
            // logging errors immediately upon encountering a versionless file. There may be
            // duplicate filenames where only one has a version, and this is ok. The highest version
            // is used.
            var versionlessFiles = fileVersions
                .Where(p =>
                    p.Key.EndsWith(".exe", StringComparison.OrdinalIgnoreCase) ||
                    p.Key.EndsWith(".dll", StringComparison.OrdinalIgnoreCase))
                .Where(p => (p.Value.FileVersion ?? ZeroVersion) == ZeroVersion)
                .Select(p => p.Value.File.ItemSpec)
                .ToArray();

            if (versionlessFiles.Any())
            {
                Log.LogError(
                    $"Missing FileVersion in {versionlessFiles.Length} shared framework files:" +
                    string.Concat(versionlessFiles.Select(f => Environment.NewLine + f)));
            }

            return !Log.HasLoggedErrors;
        }

        FileVersionData GetFileVersionData(ITaskItem file)
        {
            var filePath = file.GetMetadata("FullPath");

            if (File.Exists(filePath))
            {
                return new FileVersionData()
                {
                    AssemblyVersion = FileUtilities.GetAssemblyName(filePath)?.Version,
                    FileVersion = FileUtilities.GetFileVersion(filePath),
                    File = file
                };
            }
            else
            {
                // allow for the item to specify version directly
                Version assemblyVersion, fileVersion;

                Version.TryParse(file.GetMetadata("AssemblyVersion"), out assemblyVersion);
                Version.TryParse(file.GetMetadata("FileVersion"), out fileVersion);

                if (fileVersion == null)
                {
                    // FileVersionInfo will return 0.0.0.0 if a file doesn't have a version.
                    // match that behavior
                    fileVersion = ZeroVersion;
                }

                return new FileVersionData()
                {
                    AssemblyVersion = assemblyVersion,
                    FileVersion = fileVersion,
                    File = file
                };
            }
        }

        class FileVersionData
        {
            public Version AssemblyVersion { get; set; }
            public Version FileVersion { get; set; }
            public ITaskItem File { get; set; }
        }
    }
}