using System.Text;
using static DodoSSH.Client.Domain.Tests.HostFactory;

namespace DodoSSH.Client.Domain.Tests;

/// <summary>
/// A host reached through Spelunk: the route's own rules, how it is stored, and how it merges.
/// </summary>
/// <remarks>
/// The weight is on the compatibility rules, because a Spelunk host misread by some build is a host dialled
/// directly at an address that exists only to name its key — the one misreading that does something the
/// user never asked for.
/// </remarks>
public sealed class SpelunkRouteTests
{
    // ---- The API address ----

    [Theory]
    [InlineData("https://api.spelunk.example.com", "https://api.spelunk.example.com")]
    [InlineData("  https://API.Spelunk.Example.com/  ", "https://api.spelunk.example.com")]
    [InlineData("https://api.spelunk.example.com:8443/", "https://api.spelunk.example.com:8443")]
    [InlineData("https://example.com/spelunk/", "https://example.com/spelunk")]
    [InlineData("http://localhost:5080", "http://localhost:5080")]
    [InlineData("http://127.0.0.1:5080/", "http://127.0.0.1:5080")]
    public void AnApiAddress_IsStoredInOneForm(string typed, string stored)
    {
        // One form, so the host a link finds is the host that was saved for it however either was typed.
        SpelunkRoute.TryNormalizeApiBase(typed, out var normalized, out _).ShouldBeTrue();

        normalized.ShouldBe(stored);
    }

    [Theory]
    [InlineData("")]
    [InlineData("api.spelunk.example.com")]
    [InlineData("ftp://api.spelunk.example.com")]
    [InlineData("javascript:alert(1)")]
    [InlineData("https://user:pass@api.spelunk.example.com")]
    [InlineData("https://api.spelunk.example.com/?x=1")]
    [InlineData("https://api.spelunk.example.com/#top")]
    public void AnAddressThatIsNotASpelunkApi_IsRefused(string typed)
    {
        SpelunkRoute.TryNormalizeApiBase(typed, out _, out var reason).ShouldBeFalse();

        reason.ShouldNotBeNullOrWhiteSpace();
    }

    [Fact]
    public void PlainHttp_IsRefusedAnywhereButThisMachine()
    {
        // The key is a bearer token sent with every tunnel; in clear across a network it is somebody else's.
        SpelunkRoute.TryNormalizeApiBase("http://api.spelunk.example.com", out _, out var reason)
            .ShouldBeFalse();

        reason.ShouldNotBeNull().ShouldContain("https");
    }

    // ---- The host ----

    [Fact]
    public void AHostReachedThroughSpelunk_IsValid()
    {
        Host(spelunk: ThroughSpelunk()).TryValidate(out var reason).ShouldBeTrue(reason);
    }

    [Fact]
    public void AHostCannotTakeTheRelayAndSpelunkBoth()
    {
        Host(relayEnabled: true, spelunk: ThroughSpelunk()).TryValidate(out var reason).ShouldBeFalse();

        reason.ShouldNotBeNull().ShouldContain("not both");
    }

    [Theory]
    [InlineData("server")]
    [InlineData("key")]
    [InlineData("api")]
    public void ARouteMissingAPart_IsRefused(string missing)
    {
        var route = missing switch
        {
            "server" => ThroughSpelunk() with { ServerId = Guid.Empty },
            "key" => ThroughSpelunk() with { ApiKeyCredentialId = Guid.Empty },
            _ => ThroughSpelunk() with { ApiBase = "https://api.spelunk.example.com/" },
        };

        Host(spelunk: route).TryValidate(out _).ShouldBeFalse();
    }

    // ---- The payload ----

    [Fact]
    public void AHostReachedThroughSpelunk_RoundTrips_AtTheVersionThatIntroducedIt()
    {
        var host = Host(spelunk: ThroughSpelunk(), credentialId: Guid.CreateVersion7());

        HostSecretCodec.TryDecode(HostSecretCodec.Encode(host), out var document).ShouldBeTrue();

        document.ShouldNotBeNull();
        document.Host.ShouldBe(host);
        document.SchemaVersion.ShouldBe(HostSecretCodec.SpelunkSchemaVersion);
        document.SchemaVersion.ShouldBe(HostSecretCodec.CurrentSchemaVersion);
    }

    [Fact]
    public void AHostWithoutARoute_EncodesExactlyAsBefore()
    {
        // Not using the feature is not using the feature: no key in the JSON, and no version bump, so every
        // existing host keeps its bytes and the first sync after the upgrade pushes nothing.
        var bytes = HostSecretCodec.Encode(Host(username: null, notes: null));

        Encoding.UTF8.GetString(bytes).ShouldBe(
            """
            {"schemaVersion":1,"label":"prod-db","hostname":"db.internal","port":22,"jumpHostIds":[],"options":{},"relayEnabled":false}
            """);
    }

    [Fact]
    public void TheRoute_IsWrittenLastAndWhole()
    {
        var bytes = HostSecretCodec.Encode(Host(username: null, notes: null, spelunk: ThroughSpelunk()));

        Encoding.UTF8.GetString(bytes).ShouldBe(
            """
            {"schemaVersion":8,"label":"prod-db","hostname":"db.internal","port":22,"jumpHostIds":[],"options":{},"relayEnabled":false,"spelunk":{"api":"https://api.spelunk.example.com","serverId":"0192f0c8-bbbb-7c3d-8e4f-5a6b7c8d9e0b","apiKeyCredentialId":"0192f0c8-aaaa-7c3d-8e4f-5a6b7c8d9e0a"}}
            """);
    }

    [Fact]
    public void AnOlderPayload_StillDecodes_AsAHostThatIsDialled()
    {
        var payload = Encoding.UTF8.GetBytes(
            """
            {"schemaVersion":7,"label":"prod-db","hostname":"db.internal","port":22,"pinnedPaths":["/var/log"]}
            """);

        HostSecretCodec.TryDecode(payload, out var document).ShouldBeTrue();

        document.ShouldNotBeNull().Host.Spelunk.ShouldBeNull();
        document.IsReadOnly.ShouldBeFalse();
    }

    [Fact]
    public void AHalfWrittenRoute_MakesTheHostUnreadable_RatherThanDialled()
    {
        // The other reading — no route — would turn a damaged Spelunk host into one dialled directly.
        var payload = Encoding.UTF8.GetBytes(
            """
            {"schemaVersion":8,"label":"prod-db","hostname":"db.internal","port":22,"spelunk":{"api":"https://api.spelunk.example.com"}}
            """);

        HostSecretCodec.TryDecode(payload, out _).ShouldBeFalse();
    }

    [Fact]
    public void ARouteWrittenByANewerClient_IsReadOnlyHere()
    {
        // The rule every version before this one relies on, checked from the far side: a build that knows
        // version 8 reads a version 9 host, shows it, and refuses to re-encode what it cannot represent.
        var payload = Encoding.UTF8.GetBytes(
            """
            {"schemaVersion":9,"label":"prod-db","hostname":"db.internal","port":22,"spelunk":{"api":"https://api.spelunk.example.com","serverId":"0192f0c8-bbbb-7c3d-8e4f-5a6b7c8d9e0b","apiKeyCredentialId":"0192f0c8-aaaa-7c3d-8e4f-5a6b7c8d9e0a"},"somethingNewer":true}
            """);

        HostSecretCodec.TryDecode(payload, out var document).ShouldBeTrue();

        document.ShouldNotBeNull().IsReadOnly.ShouldBeTrue();
        document.Host.Spelunk.ShouldBe(ThroughSpelunk());
    }

    // ---- The merge ----

    [Fact]
    public void TheRoute_IsRoutedThroughTheMerge()
    {
        var ancestor = Host();
        var local = ancestor with { Spelunk = ThroughSpelunk() };

        var result = HostSecretMerge.Merge(ancestor, local, ancestor);

        result.Merged.ShouldBe(local);
        result.HasConflicts.ShouldBeFalse();
    }

    [Fact]
    public void TwoDifferentRoutes_MergeAsOneValue_AndTheDiscardedOneIsReported()
    {
        // Whole, not per part: one side's API address with the other side's server id is a route nobody
        // chose, to a server that may not exist on that Spelunk.
        var ancestor = Host();
        var local = ancestor with { Spelunk = ThroughSpelunk("https://spelunk.local.example") };
        var remote = ancestor with { Spelunk = ThroughSpelunk() with { ServerId = Guid.CreateVersion7() } };

        var result = HostSecretMerge.Merge(ancestor, local, remote);

        result.Merged.Spelunk.ShouldBe(remote.Spelunk);
        result.Conflicts.ShouldHaveSingleItem().Field.ShouldBe(nameof(HostSecret.Spelunk));
    }
}