/*
┌──────────────────────────────────────────────────────────────────┐
│  Author: Ivan Murzak (https://github.com/IvanMurzak)             │
│  Repository: GitHub (https://github.com/IvanMurzak/Unity-MCP)    │
│  Copyright (c) 2025 Ivan Murzak                                  │
│  Licensed under the Apache License, Version 2.0.                 │
│  See the LICENSE file in the project root for more information.  │
└──────────────────────────────────────────────────────────────────┘
*/
using NUnit.Framework;

namespace com.IvanMurzak.Unity.MCP.Installer.Tests
{
    public class OpenUpmVersionTests
    {
        const string SampleResponse = @"{
            ""name"": ""com.ivanmurzak.unity.mcp"",
            ""versions"": {
                ""0.1.0"": { ""version"": ""0.1.0"" },
                ""0.5.0"": { ""version"": ""0.5.0"" },
                ""0.10.0"": { ""version"": ""0.10.0"" },
                ""0.50.0"": { ""version"": ""0.50.0"" },
                ""0.51.0"": { ""version"": ""0.51.0"" },
                ""0.52.0"": { ""version"": ""0.52.0"" }
            }
        }";

        [Test]
        public void ParseBestVersion_ExactVersionExists_ReturnsIt()
        {
            var result = Installer.ParseBestVersion(SampleResponse, "0.52.0");

            Assert.AreEqual("0.52.0", result,
                "Should return the exact version when it exists on OpenUPM");
        }

        [Test]
        public void ParseBestVersion_ExactVersionMissing_ReturnsHighestBelow()
        {
            var result = Installer.ParseBestVersion(SampleResponse, "0.53.0");

            Assert.AreEqual("0.52.0", result,
                "Should return the highest available version below the target");
        }

        [Test]
        public void ParseBestVersion_OnlyNewerVersionsExist_ReturnsNull()
        {
            var result = Installer.ParseBestVersion(SampleResponse, "0.0.1");

            Assert.IsNull(result,
                "Should return null when all available versions are newer than the target");
        }

        [Test]
        public void ParseBestVersion_MalformedJson_ReturnsNull()
        {
            var result = Installer.ParseBestVersion("not valid json {{{", "0.52.0");

            Assert.IsNull(result,
                "Should return null for malformed JSON");
        }

        [Test]
        public void ParseBestVersion_EmptyVersions_ReturnsNull()
        {
            var json = @"{ ""name"": ""pkg"", ""versions"": {} }";
            var result = Installer.ParseBestVersion(json, "0.52.0");

            Assert.IsNull(result,
                "Should return null when versions object is empty");
        }

        [Test]
        public void ParseBestVersion_NullInput_ReturnsNull()
        {
            Assert.IsNull(Installer.ParseBestVersion(null, "0.52.0"),
                "Should return null for null JSON input");

            Assert.IsNull(Installer.ParseBestVersion(SampleResponse, null),
                "Should return null for null maxVersion");
        }

        [Test]
        public void ParseBestVersion_EmptyStringInput_ReturnsNull()
        {
            Assert.IsNull(Installer.ParseBestVersion("", "0.52.0"),
                "Should return null for empty JSON input");

            Assert.IsNull(Installer.ParseBestVersion(SampleResponse, ""),
                "Should return null for empty maxVersion");
        }

        [Test]
        public void ParseBestVersion_NoVersionsKey_ReturnsNull()
        {
            var json = @"{ ""name"": ""pkg"" }";
            var result = Installer.ParseBestVersion(json, "0.52.0");

            Assert.IsNull(result,
                "Should return null when JSON has no versions key");
        }

        [Test]
        public void ParseBestVersion_SkipsInvalidVersionStrings()
        {
            var json = @"{
                ""versions"": {
                    ""invalid"": {},
                    ""0.10.0"": {},
                    ""also-bad"": {},
                    ""0.5.0"": {}
                }
            }";
            var result = Installer.ParseBestVersion(json, "0.52.0");

            Assert.AreEqual("0.10.0", result,
                "Should skip invalid version strings and return the highest valid one");
        }

        [Test]
        public void ParseBestVersion_SelectsCorrectVersionAmongMany()
        {
            var result = Installer.ParseBestVersion(SampleResponse, "0.51.0");

            Assert.AreEqual("0.51.0", result,
                "Should select the exact version when it exists, even when higher versions are available");
        }
    }
}