// 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 System.Net.Http;
using System.Text;
using System.Threading;
using System.Threading.Tasks;
using System.Xml;
using System.Xml.Linq;
using Microsoft.Extensions.CommandLineUtils;
using NuGet.Common;
using NuGet.Configuration;
using NuGet.Packaging;
using NuGet.Protocol;
using NuGet.Protocol.Core.Types;
using NuGet.Versioning;

namespace PackageBaselineGenerator;

/// <summary>
/// This generates Baseline.props with information about the last RTM release.
/// </summary>
class Program : CommandLineApplication
{
    static void Main(string[] args)
    {
        new Program().Execute(args);
    }

    private readonly CommandOption _sources;
    private readonly CommandOption _output;
    private readonly CommandOption _update;

    private static readonly string[] _defaultSources = new string[] { "https://api.nuget.org/v3/index.json" };

    public Program()
    {
        _sources = Option(
            "-s|--package-sources <Sources>",
            "The NuGet source(s) of packages to fetch",
            CommandOptionType.MultipleValue);
        _output = Option("-o|--output <OUT>", "The generated file output path", CommandOptionType.SingleValue);
        _update = Option("-u|--update", "Regenerate the input (Baseline.xml) file.", CommandOptionType.NoValue);

        Invoke = () => Run().GetAwaiter().GetResult();
    }

    private async Task<int> Run()
    {
        if (_output.HasValue() && _update.HasValue())
        {
            await Error.WriteLineAsync("'--output' and '--update' options must not be used together.");
            return 1;
        }

        var inputPath = Path.Combine(Directory.GetCurrentDirectory(), "Baseline.xml");
        var input = XDocument.Load(inputPath);
        var sources = _sources.HasValue() ? _sources.Values.Select(s => s.TrimEnd('/')) : _defaultSources;
        var packageSources = sources.Select(s => new PackageSource(s));
        var providers = Repository.Provider.GetCoreV3(); // Get v2 and v3 API support
        var sourceRepositories = packageSources.Select(ps => new SourceRepository(ps, providers));
        if (_update.HasValue())
        {
            var updateResult = await RunUpdateAsync(inputPath, input, sourceRepositories);
            if (updateResult != 0)
            {
                return updateResult;
            }
        }

        List<(string packageBase, bool feedV3)> packageBases = new List<(string, bool)>();
        foreach (var sourceRepository in sourceRepositories)
        {
            var feedType = await sourceRepository.GetFeedType(CancellationToken.None);
            var feedV3 = feedType == FeedType.HttpV3;
            var packageBase = sourceRepository.PackageSource + "/package";
            if (feedV3)
            {
                var resources = await sourceRepository.GetResourceAsync<ServiceIndexResourceV3>();
                packageBase = resources.GetServiceEntryUri(ServiceTypes.PackageBaseAddress).ToString().TrimEnd('/');
            }

            packageBases.Add((packageBase, feedV3));
        }

        var output = _output.HasValue()
            ? _output.Value()
            : Path.Combine(Directory.GetCurrentDirectory(), "Baseline.Designer.props");

        var packageCache = Environment.GetEnvironmentVariable("NUGET_PACKAGES") ??
            Path.Combine(Environment.GetFolderPath(Environment.SpecialFolder.UserProfile), ".nuget", "packages");

        var tempDir = Path.Combine(Directory.GetCurrentDirectory(), "obj", "tmp");
        Directory.CreateDirectory(tempDir);

        var baselineVersion = input.Root.Attribute("Version").Value;

        // Baseline and .NET Core versions always align in non-preview releases.
        var parsedVersion = Version.Parse(baselineVersion);
        var defaultTarget = ((parsedVersion.Major < 5) ? "netcoreapp" : "net") +
            $"{parsedVersion.Major}.{parsedVersion.Minor}";

        var doc = new XDocument(
            new XComment(" Auto generated. Do not edit manually, use eng/tools/BaselineGenerator/ to recreate. "),
            new XElement("Project",
                new XElement("PropertyGroup",
                    new XElement("MSBuildAllProjects", "$(MSBuildAllProjects);$(MSBuildThisFileFullPath)"),
                    new XElement("AspNetCoreBaselineVersion", baselineVersion))));

        var client = new HttpClient();
        foreach (var pkg in input.Root.Descendants("Package"))
        {
            var id = pkg.Attribute("Id").Value;
            var version = pkg.Attribute("Version").Value;
            var packageFileName = $"{id}.{version}.nupkg";
            var nupkgPath = Path.Combine(packageCache, id.ToLowerInvariant(), version, packageFileName);
            if (!File.Exists(nupkgPath))
            {
                nupkgPath = Path.Combine(tempDir, packageFileName);
            }

            if (!File.Exists(nupkgPath))
            {
                foreach ((string packageBase, bool feedV3) in packageBases)
                {
                    var url = feedV3 ?
                        $"{packageBase}/{id.ToLowerInvariant()}/{version}/{id.ToLowerInvariant()}.{version}.nupkg" :
                        $"{packageBase}/{id}/{version}";

                    Console.WriteLine($"Downloading {url}");
                    try
                    {
                        using (var response = await client.GetStreamAsync(url))
                        {
                            using (var file = File.Create(nupkgPath))
                            {
                                await response.CopyToAsync(file);
                            }
                        }
                    }
                    catch (HttpRequestException e) when (e.StatusCode == System.Net.HttpStatusCode.NotFound)
                    {
                        // If it's not found, continue onto the next one.
                        continue;
                    }
                }

                if (!File.Exists(nupkgPath))
                {
                    throw new Exception($"Could not download package {id} @ {version} using any input feed");
                }
            }

            using (var reader = new PackageArchiveReader(nupkgPath))
            {
                doc.Root.Add(new XComment($" Package: {id}"));

                var propertyGroup = new XElement(
                    "PropertyGroup",
                    new XAttribute("Condition", $" '$(PackageId)' == '{id}' "),
                    new XElement("BaselinePackageVersion", version));
                doc.Root.Add(propertyGroup);

                foreach (var group in reader.NuspecReader.GetDependencyGroups())
                {
                    // Don't bother generating empty ItemGroup elements.
                    if (!group.Packages.Any())
                    {
                        continue;
                    }

                    // Handle changes to $(DefaultNetCoreTargetFramework) even if some projects are held back.
                    var targetCondition = $"'$(TargetFramework)' == '{group.TargetFramework.GetShortFolderName()}'";
                    if (string.Equals(
                        group.TargetFramework.GetShortFolderName(),
                        defaultTarget,
                        StringComparison.OrdinalIgnoreCase))
                    {
                        targetCondition =
                            $"('$(TargetFramework)' == '$(DefaultNetCoreTargetFramework)' OR '$(TargetFramework)' == '{defaultTarget}')";
                    }

                    var itemGroup = new XElement(
                        "ItemGroup",
                        new XAttribute("Condition", $" '$(PackageId)' == '{id}' AND {targetCondition} "));
                    doc.Root.Add(itemGroup);

                    foreach (var dependency in group.Packages)
                    {
                        itemGroup.Add(
                            new XElement("BaselinePackageReference",
                            new XAttribute("Include", dependency.Id),
                            new XAttribute("Version", dependency.VersionRange.ToString())));
                    }
                }
            }
        }

        var settings = new XmlWriterSettings
        {
            OmitXmlDeclaration = true,
            Encoding = Encoding.UTF8,
            Indent = true,
        };

        using (var writer = XmlWriter.Create(output, settings))
        {
            doc.Save(writer);
        }

        Console.WriteLine($"Generated file in {output}");

        return 0;
    }

    private async Task<int> RunUpdateAsync(
        string documentPath,
        XDocument document,
        IEnumerable<SourceRepository> sourceRepositories)
    {
        var packageMetadataResources = await Task.WhenAll(sourceRepositories.Select(async sr =>
            await sr.GetResourceAsync<PackageMetadataResource>()));

        var logger = new Logger(Error, Out);
        var hasChanged = false;
        using (var cacheContext = new SourceCacheContext { NoCache = true })
        {
            var versionAttribute = document.Root.Attribute("Version");
            hasChanged = await TryUpdateVersionAsync(
                versionAttribute,
                "Microsoft.AspNetCore.App.Runtime.win-x64",
                packageMetadataResources,
                logger,
                cacheContext);

            foreach (var package in document.Root.Descendants("Package"))
            {
                var id = package.Attribute("Id").Value;
                versionAttribute = package.Attribute("Version");
                var attributeChanged = await TryUpdateVersionAsync(
                    versionAttribute,
                    id,
                    packageMetadataResources,
                    logger,
                    cacheContext);

                hasChanged |= attributeChanged;
            }
        }

        if (hasChanged)
        {
            await Out.WriteLineAsync($"Updating {documentPath}.");

            var settings = new XmlWriterSettings
            {
                Async = true,
                CheckCharacters = true,
                CloseOutput = false,
                Encoding = Encoding.UTF8,
                Indent = true,
                IndentChars = "  ",
                NewLineOnAttributes = false,
                OmitXmlDeclaration = true,
                WriteEndDocumentOnClose = true,
            };

            using (var stream = File.OpenWrite(documentPath))
            {
                using (var writer = XmlWriter.Create(stream, settings))
                {
                    await document.SaveAsync(writer, CancellationToken.None);
                }
            }
        }
        else
        {
            await Out.WriteLineAsync("No new versions found");
        }

        return 0;
    }

    private static async Task<bool> TryUpdateVersionAsync(
        XAttribute versionAttribute,
        string packageId,
        IEnumerable<PackageMetadataResource> packageMetadataResources,
        ILogger logger,
        SourceCacheContext cacheContext)
    {
        var currentVersion = NuGetVersion.Parse(versionAttribute.Value);
        var versionRange = new VersionRange(
            currentVersion,
            new FloatRange(NuGetVersionFloatBehavior.Patch, currentVersion));

        var searchMetadatas = await Task.WhenAll(
            packageMetadataResources.Select(async pmr => await pmr.GetMetadataAsync(
                packageId,
                includePrerelease: false,
                includeUnlisted: true, // Microsoft.AspNetCore.DataOrotection.Redis package is not listed.
                sourceCacheContext: cacheContext,
                log: logger,
                token: CancellationToken.None)));

        // Find the latest version among each search metadata
        NuGetVersion latestVersion = null;
        foreach (var searchMetadata in searchMetadatas)
        {
            var potentialLatestVersion = versionRange.FindBestMatch(
                searchMetadata.Select(metadata => metadata.Identity.Version));
            if (latestVersion == null ||
                (potentialLatestVersion != null && potentialLatestVersion.CompareTo(latestVersion) > 0))
            {
                latestVersion = potentialLatestVersion;
            }
        }

        if (latestVersion == null)
        {
            logger.LogWarning($"Unable to find latest version of '{packageId}'.");
            return false;
        }

        var hasChanged = false;
        if (latestVersion != currentVersion)
        {
            hasChanged = true;
            versionAttribute.Value = latestVersion.ToNormalizedString();
        }

        return hasChanged;
    }

    private class Logger : ILogger
    {
        private readonly TextWriter _error;
        private readonly TextWriter _out;

        public Logger(TextWriter error, TextWriter @out)
        {
            _error = error;
            _out = @out;
        }

        public void Log(LogLevel level, string data)
        {
            switch (level)
            {
                case LogLevel.Debug:
                    LogDebug(data);
                    break;
                case LogLevel.Error:
                    LogError(data);
                    break;
                case LogLevel.Information:
                    LogInformation(data);
                    break;
                case LogLevel.Minimal:
                    LogMinimal(data);
                    break;
                case LogLevel.Verbose:
                    LogVerbose(data);
                    break;
                case LogLevel.Warning:
                    LogWarning(data);
                    break;
            }
        }

        public void Log(ILogMessage message) => Log(message.Level, message.Message);

        public Task LogAsync(LogLevel level, string data)
        {
            Log(level, data);
            return Task.CompletedTask;
        }

        public Task LogAsync(ILogMessage message) => LogAsync(message.Level, message.Message);

        public void LogDebug(string data) => _out.WriteLine($"Debug: {data}");

        public void LogError(string data) => _error.WriteLine($"Error: {data}");

        public void LogInformation(string data) => _out.WriteLine($"Information: {data}");

        public void LogInformationSummary(string data) => _out.WriteLine($"Summary: {data}");

        public void LogMinimal(string data) => _out.WriteLine($"Minimal: {data}");

        public void LogVerbose(string data) => _out.WriteLine($"Verbose: {data}");

        public void LogWarning(string data) => _out.WriteLine($"Warning: {data}");
    }
}