using System;
using Newtonsoft.Json.Linq;
using NUnit.Framework;
using UnityEngine;
using UnityEngine.TestTools;

namespace ShrinkDataSaver.Tests
{
    [TestFixture]
    public class MigrationChainTests
    {
        [SetUp]
        public void SetUp() => MigrationChain.Clear();

        [TearDown]
        public void TearDown() => MigrationChain.Clear();

        [Test]
        public void Register_ValidVersions_Succeeds()
        {
            Assert.DoesNotThrow(() =>
                MigrationChain.Register(1, 2, data => data));
        }

        [Test]
        public void Register_InvalidRange_Throws()
        {
            Assert.Throws<ArgumentException>(() =>
                MigrationChain.Register(2, 1, data => data));

            Assert.Throws<ArgumentException>(() =>
                MigrationChain.Register(1, 1, data => data));
        }

        [Test]
        public void Apply_SingleMigration()
        {
            MigrationChain.Register(1, 2, data =>
            {
                data["newField"] = "added";
                return data;
            });

            var input = new JObject { ["existing"] = "value" };
            var (result, version) = MigrationChain.Apply(input, 1, 2);

            Assert.AreEqual(2, version);
            Assert.AreEqual("value", result["existing"].ToString());
            Assert.AreEqual("added", result["newField"].ToString());
        }

        [Test]
        public void Apply_ChainMigration_1To3()
        {
            MigrationChain.Register(1, 2, data =>
            {
                data["coins"] = data["gold"];
                data.Remove("gold");
                return data;
            });

            MigrationChain.Register(2, 3, data =>
            {
                data["version3Field"] = 42;
                return data;
            });

            var input = new JObject { ["gold"] = 100 };
            var (result, version) = MigrationChain.Apply(input, 1, 3);

            Assert.AreEqual(3, version);
            Assert.AreEqual(100, result["coins"].Value<int>());
            Assert.IsFalse(result.ContainsKey("gold"));
            Assert.AreEqual(42, result["version3Field"].Value<int>());
        }

        [Test]
        public void Apply_MissingStep_StopsEarly()
        {
            MigrationChain.Register(1, 2, data => data);
            // 缺少 2→3 的迁移

            var input = new JObject { ["data"] = "test" };
            var (result, version) = MigrationChain.Apply(input, 1, 3);

            // 应该停在 v2，因为没有 2→3 的迁移
            Assert.AreEqual(2, version);
        }

        [Test]
        public void Apply_FailedMigration_Rollback()
        {
            MigrationChain.Register(1, 2, data =>
            {
                data["step1"] = "done";
                return data;
            });

            MigrationChain.Register(2, 3, data =>
            {
                throw new Exception("Migration failed!");
            });

            var input = new JObject { ["original"] = "data" };
            LogAssert.Expect(LogType.Error, "[ShrinkDataSaver] 迁移 v2 → v3 失败: Migration failed!，已回滚至 v1");
            var (result, version) = MigrationChain.Apply(input, 1, 3);

            // 应该回滚到 v1 的备份数据
            Assert.AreEqual(1, version);
            Assert.AreEqual("data", result["original"].ToString());
            // 回滚意味着 step1 的修改不会存在
            Assert.IsFalse(result.ContainsKey("step1"));
        }

        [Test]
        public void Apply_NoMigrationNeeded_ReturnsSameData()
        {
            var input = new JObject { ["data"] = "unchanged" };
            var (result, version) = MigrationChain.Apply(input, 3, 3);

            Assert.AreEqual(3, version);
            Assert.AreEqual("unchanged", result["data"].ToString());
        }
    }
}