using Admin.NET.Core.Update;
using Xunit;

namespace Admin.NET.Plugin.AiDOP.Tests.Migration;

/// <summary>
/// 已登记「迁移记录被误记」重整策略的契约。
///
/// <para>被守护的核心不变量有两条，方向相反、同等重要：</para>
///
/// <para><b>① 不能误伤正常环境。</b>闸门 1–4 任一不成立必须返回 None——
/// 全新环境（无日志行）、已升级完成的环境（hash 已是目标值）、失败重试中的环境（非 Success），
/// 这三种都是正常状态，一旦在这里 Reject 就是把好好的库打死。
/// 其中「已升级完成」最危险：它与事故环境只差 file_hash 一个字段。</para>
///
/// <para><b>② 命中事故签名之后不能沉默放行。</b>闸门 5–7 是安全前提，
/// 任一不成立必须 Reject 停机，绝不允许降级成「跳过重整继续启动」——
/// 该通道会修改迁移历史，沉默放行等于在无人知晓的情况下改写执行史。</para>
///
/// <para>策略是纯函数，故这些用例不需要数据库；副作用（UPDATE / 抛异常）由
/// AutoVersionUpdate 执行，其真实运行结果由隔离库的 First Run / Second Run 覆盖。</para>
/// </summary>
public class MigrationCollisionPolicyTests
{
    private const string V = "1.0.536";
    private const string CollidedHash = "970E5A8F0133944CB04AC95E67112A2EC6E2E45F06AE61C3F2049163F7DC9A61";
    private const string TargetHash = "5A18A15AB379167A151C317A18617E2841EC4E808C8FD727216360D81EA76776";
    private const string DisplacedV = "1.0.539";
    private const string DisplacedHash = "9B627E41C15EBB5195C035592870E56A9EDE5704FA423DDEC5A4A8FF94A6CE42";

    /// <summary>事故现场的完整参数；各用例只改动自己要验证的那一个维度。</summary>
    private static MigrationCollisionOutcome Decide(
        string version = V,
        int matchedRowCount = 1,
        string? loggedStatus = "Success",
        string? loggedFileHash = CollidedHash,
        bool targetDiskHashMatches = true,
        string? displacedLoggedStatus = "Success",
        string? displacedLoggedFileHash = DisplacedHash,
        bool displacedDiskHashMatches = true)
        => MigrationCollisionPolicy.Decide(
            version, matchedRowCount, loggedStatus, loggedFileHash, targetDiskHashMatches,
            displacedLoggedStatus, displacedLoggedFileHash, displacedDiskHashMatches);

    // ── 正向：只有事故现场本身才允许重整 ────────────────────────────────────────────

    [Fact]
    public void ExactAccidentSignature_ResetsRecord()
    {
        var outcome = Decide();

        Assert.Equal(MigrationCollisionDecision.ResetCollidedRecord, outcome.Decision);
        Assert.Equal("COLLISION_STATUS_RESET", outcome.Plan!.Strategy);
        Assert.Equal(DisplacedV, outcome.Plan.DisplacedVersion);
        Assert.Null(outcome.RejectReason);
    }

    /// <summary>不同驱动回读 hash / status 的形态不一致，大小写与首尾空白不应改变裁决。</summary>
    [Theory]
    [InlineData("Success", "970e5a8f0133944cb04ac95e67112a2ec6e2e45f06ae61c3f2049163f7dc9a61")]
    [InlineData("SUCCESS", "  " + CollidedHash + "  ")]
    [InlineData("success", CollidedHash)]
    public void CaseInsensitiveAndTrimmed_StillResets(string status, string hash)
        => Assert.Equal(
            MigrationCollisionDecision.ResetCollidedRecord,
            Decide(loggedStatus: status, loggedFileHash: hash).Decision);

    // ── 闸门 1–4：正常环境一律 None，绝不 Reject ──────────────────────────────────

    [Fact]
    public void UnregisteredVersion_IsNone()
    {
        var outcome = Decide(version: "1.0.551");

        Assert.Equal(MigrationCollisionDecision.None, outcome.Decision);
        Assert.Null(outcome.Plan);
    }

    /// <summary>全新环境：该版本从未跑过 ⇒ 正常首次执行，不是事故场景。</summary>
    [Fact]
    public void FreshEnvironmentWithNoRow_IsNone()
        => Assert.Equal(MigrationCollisionDecision.None, Decide(matchedRowCount: 0, loggedStatus: null, loggedFileHash: null).Decision);

    /// <summary>唯一键理论上保证不会有多行；真出现了也只能停手，不能猜该动哪一行。</summary>
    [Fact]
    public void MultipleRowsForVersion_IsNone()
        => Assert.Equal(MigrationCollisionDecision.None, Decide(matchedRowCount: 2).Decision);

    [Theory]
    [InlineData("Failed")]
    [InlineData("Running")]
    [InlineData("Skipped")]
    [InlineData("Superseded")]
    public void NonSuccessStatus_IsNone(string status)
        => Assert.Equal(MigrationCollisionDecision.None, Decide(loggedStatus: status).Decision);

    /// <summary>
    /// 最危险的一条：<b>已经升级完成</b>的环境，记录里是目标 hash + Success。
    /// 它与事故环境只差 file_hash 一个字段，若这里 Reject 就会把所有正常环境打死，
    /// 必须放行给 ShouldSkipScript 按常规「hash 未变 ⇒ 跳过」处理。
    /// </summary>
    [Fact]
    public void AlreadyUpgradedEnvironment_IsNone_NotReject()
    {
        var outcome = Decide(loggedFileHash: TargetHash);

        Assert.Equal(MigrationCollisionDecision.None, outcome.Decision);
        Assert.Null(outcome.RejectReason);
    }

    /// <summary>某个我们没见过的 1.0.536 ⇒ 不认领，交给既有 hash 守卫去拒绝启动。</summary>
    [Fact]
    public void UnknownHashForRegisteredVersion_IsNone()
        => Assert.Equal(
            MigrationCollisionDecision.None,
            Decide(loggedFileHash: "0000000000000000000000000000000000000000000000000000000000000000").Decision);

    // ── 闸门 5–7：命中签名后，安全前提不成立一律 Reject ────────────────────────────

    /// <summary>命中事故签名但磁盘不是目标 revision ⇒ 重整后会跑出未预期的脚本，必须停机。</summary>
    [Fact]
    public void SignatureMatchedButWrongRevision_Rejects()
    {
        var outcome = Decide(targetDiskHashMatches: false);

        Assert.Equal(MigrationCollisionDecision.Reject, outcome.Decision);
        Assert.Contains(TargetHash, outcome.RejectReason);
    }

    /// <summary>
    /// 最关键的一道：被顶替的内容必须已被合法记录在案。
    /// 拿不出这个证据就重整，等于可能抹掉一次真实发生过的执行史。
    /// </summary>
    [Theory]
    [InlineData(null, DisplacedHash)]
    [InlineData("Failed", DisplacedHash)]
    [InlineData("Success", null)]
    [InlineData("Success", "0000000000000000000000000000000000000000000000000000000000000000")]
    public void DisplacedContentNotProvenRecorded_Rejects(string? status, string? hash)
    {
        var outcome = Decide(displacedLoggedStatus: status, displacedLoggedFileHash: hash);

        Assert.Equal(MigrationCollisionDecision.Reject, outcome.Decision);
        Assert.Contains(DisplacedV, outcome.RejectReason);
    }

    /// <summary>磁盘上的被顶替脚本也必须仍是登记的那一份，否则「已记录的」与「本 revision 携带的」不是同一个东西。</summary>
    [Fact]
    public void DisplacedScriptOnDiskDiffers_Rejects()
        => Assert.Equal(MigrationCollisionDecision.Reject, Decide(displacedDiskHashMatches: false).Decision);

    // ── 幂等：三种中断/完成状态下的收敛行为 ──────────────────────────────────────

    /// <summary>First Run 成功后：hash 已是目标值 ⇒ 永不再触发。</summary>
    [Fact]
    public void AfterSuccessfulFirstRun_NeverTriggersAgain()
        => Assert.Equal(MigrationCollisionDecision.None, Decide(loggedFileHash: TargetHash).Decision);

    /// <summary>重整后崩溃（Superseded + 旧 hash）：闸门 3 不成立 ⇒ None；
    /// 而 ShouldSkipScript 对非 Success 行返回 false，脚本照常执行，仍然收敛。</summary>
    [Fact]
    public void AfterResetButBeforeExecution_IsNone_SoNormalFlowProceeds()
        => Assert.Equal(
            MigrationCollisionDecision.None,
            Decide(loggedStatus: MigrationCollisionPolicy.SupersededStatus).Decision);

    /// <summary>正式脚本执行失败（目标 hash + Failed）：走常规重试，不再经过本策略。</summary>
    [Fact]
    public void AfterFailedExecution_IsNone()
        => Assert.Equal(
            MigrationCollisionDecision.None,
            Decide(loggedStatus: "Failed", loggedFileHash: TargetHash).Decision);

    // ── 登记表本身的约束 ────────────────────────────────────────────────────────

    /// <summary>
    /// 登记表只应包含这一条已评审的事故。新增条目 = 授权一次对迁移历史的修改，
    /// 必须先更新本用例，以强制评审发生。
    /// </summary>
    [Fact]
    public void RegistryContainsOnlyTheReviewedCollision()
    {
        var plan = Assert.Single(MigrationCollisionPolicy.KnownCollisions);

        Assert.Equal(V, plan.Version);
        Assert.Equal(CollidedHash, plan.CollidedFileHash);
        Assert.Equal(TargetHash, plan.ExpectedDiskHash);
        Assert.Equal(DisplacedV, plan.DisplacedVersion);
        Assert.Equal(DisplacedHash, plan.DisplacedFileHash);
    }

    /// <summary>
    /// 重整写入的中间状态必须避开全部既有状态值，否则会被正常流程误解
    /// （例如被 successVersions 统计、或被失败恢复策略认领）。
    /// </summary>
    [Fact]
    public void SupersededStatusDoesNotCollideWithExistingStatuses()
    {
        foreach (var existing in new[] { "Running", "Success", "Failed", "Skipped" })
            Assert.NotEqual(existing, MigrationCollisionPolicy.SupersededStatus, StringComparer.OrdinalIgnoreCase);
    }
}