// 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 Newtonsoft.Json;
using Newtonsoft.Json.Linq;
using System;
using System.IO;
using System.Linq;

namespace Microsoft.DotNet.Build.Tasks.VisualStudio;

/// <summary>
/// Find the latest drop in a JSON list of VS drops.
/// </summary>
[MSBuildMultiThreadableTask]
public sealed class FindLatestDrop : 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>
    /// Full path to JSON file containing list of drops.
    /// </summary>
    [Required]
    public string DropListPath { get; set; }

    /// <summary>
    /// The name of the latest drop.
    /// </summary>
    [Output]
    public string DropName { get; private set; }

    public override bool Execute()
    {
        ExecuteImpl();
        return !Log.HasLoggedErrors;
    }

    private void ExecuteImpl()
    {
        try
        {
            DropName = GetLatestDropName(File.ReadAllText(TaskEnvironment.GetAbsolutePath(DropListPath)));
        }
        catch (Exception e)
        {
            Log.LogError($"Error parsing file '{DropListPath}': {e.Message}");
            return;
        }
    }

    internal static string GetLatestDropName(string json)
    {
        JObject candidate = null;
        DateTime latest = default;

        JArray drops = JArray.Parse(json);

        if (drops.Count == 0)
        {
            throw new ApplicationException("No drops matching the specified prefix were returned");
        }

        foreach (JObject item in drops)
        {
            var timestampToken = item["CreatedDateUtc"];
            if (timestampToken?.Type != JTokenType.Date)
            {
                throw new ApplicationException($"Invalid timestamp: '{item["CreatedDateUtc"]}'");
            }

            var timestamp = timestampToken.Value<DateTime>();

            if (string.IsNullOrEmpty((string)item["Name"]))
            {
                throw new ApplicationException($"Drop has no name: {item}");
            }

            if (candidate == null || (bool)item["UploadComplete"] && !(bool)item["DeletePending"] && timestamp > latest)
            {
                candidate = item;
                latest = timestamp;
            }
        }

        if (candidate == null)
        {
            throw new ApplicationException($"No complete, undeleted drops found");
        }

        return (string)candidate["Name"];
    }
}