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

using Microsoft.Build.Framework;
using Microsoft.Build.Utilities;
using System;
using System.Linq;
using System.Xml.Linq;

namespace Microsoft.DotNet.Build.Tasks.Installers;

/// <summary>
/// In a WiX source file, replaces the Id of a File with some given string in order to stabilize
/// it. This allows external tooling such as signature validators to rely on a stable identifier
/// for certain files.
/// </summary>
[MSBuildMultiThreadableTask]
public class StabilizeWixFileId : Task, IMultiThreadableTask
{
    /// <summary>Injected by MSBuild so paths resolve against the project directory in multithreaded builds.</summary>
    public TaskEnvironment TaskEnvironment { get; set; } = TaskEnvironment.Fallback;

    /// <summary>
    /// File to read from. This is expected to be an output from heat.exe.
    /// 
    /// Expected format:
    /// 
    ///   <?xml version="1.0" encoding="utf-8"?>
    ///   <Wix xmlns="http://schemas.microsoft.com/wix/2006/wi">
    ///       <Fragment>
    ///           <ComponentGroup Id="InstallFiles">
    ///               <Component Id="cmp680C9..." Directory="dir14B9F..." Guid="{C31...}">
    ///                   <File Id="filE57B7..." KeyPath="yes" Source="$(var.PackSrc)\packs\...\native\apphost.exe" />
    ///                   ...
    /// </summary>
    [Required]
    public string SourceFile { get; set; }

    /// <summary>
    /// File to write to. May be the same as SourceFile.
    /// </summary>
    [Required]
    public string OutputFile { get; set; }

    /// <summary>
    /// Set of files to stabilize. This matches the end of the "Source" attribute in the WiX
    /// source file. If exactly one match isn't found in the WiX source file, this task fails.
    /// 
    /// %(Identity): The file source to replace.
    /// %(ReplacementId): The replacement for Id that won't change per-build.
    /// </summary>
    [Required]
    public ITaskItem[] FileElementToStabilize { get; set; }

    public override bool Execute()
    {
        XDocument content = XDocument.Load(TaskEnvironment.GetAbsolutePath(SourceFile));

        XNamespace rootNamespace = content.Root.GetDefaultNamespace();
        XName GetQualifiedName(string name) => rootNamespace.GetName(name);

        foreach (var file in FileElementToStabilize)
        {
            string replacement = file.GetMetadata("ReplacementId");

            if (string.IsNullOrEmpty(replacement))
            {
                Log.LogError($"{nameof(FileElementToStabilize)} {file.ItemSpec} has null/empty ReplacementId metadata.");
                continue;
            }

            XElement[] matchingFileElements = content.Element(GetQualifiedName("Wix"))
                .Elements(GetQualifiedName("Fragment"))
                .SelectMany(f => f.Elements(GetQualifiedName("ComponentGroup")))
                .SelectMany(cg => cg.Elements(GetQualifiedName("Component")))
                .SelectMany(c => c.Elements(GetQualifiedName("File")))
                .Where(f => f.Attribute("Source")?.Value
                    ?.EndsWith(file.ItemSpec, StringComparison.OrdinalIgnoreCase) == true)
                .ToArray();

            if (matchingFileElements.Length != 1)
            {
                Log.LogError(
                    $"Expected 1 match for '{file.ItemSpec}', found {matchingFileElements.Length}: " +
                    string.Join(", ", matchingFileElements.Select(e => e.ToString())));

                continue;
            }

            XAttribute nameAttribute = matchingFileElements[0].Attribute("Id");

            if (nameAttribute is null)
            {
                Log.LogError($"Match has no Id attribute: {matchingFileElements[0]}");
                continue;
            }

            Log.LogMessage(
                $"Setting '{file.ItemSpec}' Id to '{replacement}' for File with Source " +
                matchingFileElements[0].Attribute("Source").Value);

            nameAttribute.Value = replacement;
        }

        content.Save(TaskEnvironment.GetAbsolutePath(OutputFile));

        return !Log.HasLoggedErrors;
    }
}