using System.Text;

using DodoSSH.Client.Session;
using DodoSSH.Client.Shell.Keyboard;
using DodoSSH.Client.Shell.ViewModels;
using DodoSSH.Client.Terminal;

namespace DodoSSH.Client.App.Tests;

/// <summary>
/// The phone's terminal keys: what each sends, what a latch does to the next one, the cursor gesture's
/// speeds, the history's refusal to keep what was not echoed, and the arrangement surviving a relaunch.
/// </summary>
public sealed class TerminalKeyboardTests : IDisposable
{
    private readonly string directory =
        Path.Combine(Path.GetTempPath(), $"dodossh-keys-{Guid.CreateVersion7():N}");

    private readonly List<byte[]> sent = [];

    /// <summary>What the remote has drawn so far, as the history's echo test reads it.</summary>
    private string screen = "stan@box:~$ ";

    public void Dispose()
    {
        if (Directory.Exists(directory))
        {
            Directory.Delete(directory, recursive: true);
        }
    }

    private static byte[] Ascii(string text) => Encoding.ASCII.GetBytes(text);

    private static string Shown(byte[] bytes) => Encoding.ASCII.GetString(bytes);

    // ── notation ─────────────────────────────────────────────────────────────────────────────────────────

    [Theory]
    [InlineData(@"\e:wq\r", "\x1b:wq\r")]
    [InlineData("^C", "\x03")]
    [InlineData("^c", "\x03")]
    [InlineData("^[", "\x1b")]
    [InlineData("^?", "\x7f")]
    [InlineData(@"\x1b[A", "\x1b[A")]
    [InlineData(@"\^C", "^C")]
    [InlineData("^1", "^1")]
    [InlineData("git status", "git status")]
    [InlineData(@"a\\b", @"a\b")]
    public void Notation_IsReadTheWayATerminalUserWritesIt(string notation, string expected)
    {
        KeySequence.TryParse(notation, out var bytes).ShouldBeTrue();

        Shown(bytes).ShouldBe(expected);
    }

    [Theory]
    [InlineData(@"oops\")]
    [InlineData(@"\x1")]
    [InlineData(@"\xZZ")]
    public void MalformedNotation_IsRefusedRatherThanGuessedAt(string notation) =>
        KeySequence.TryParse(notation, out _).ShouldBeFalse();

    // ── latches ──────────────────────────────────────────────────────────────────────────────────────────

    [Theory]
    [InlineData("c", true, false, "\x03")]
    [InlineData("C", true, false, "\x03")]
    [InlineData(" ", true, false, "\0")]
    [InlineData("b", false, true, "\u001bb")]
    [InlineData("\x1b[D", true, false, "\x1b[1;5D")]
    [InlineData("\x1b[C", true, true, "\x1b[1;7C")]
    [InlineData("\x1b[A", false, true, "\x1b[1;3A")]
    [InlineData("ls", true, false, "ls")]
    [InlineData("\x1b[15~", true, false, "\x1b[15~")]
    public void ALatchedModifier_EncodesTheNextKeyTheWayXtermDoes(string key, bool control, bool alt, string expected) =>
        Shown(TerminalModifiers.Apply(Ascii(key), control, alt)).ShouldBe(expected);

    // ── the cursor gesture ───────────────────────────────────────────────────────────────────────────────

    [Fact]
    public void ADragInsideTheDeadZone_SendsNothing()
    {
        var gesture = new ArrowGesture();

        gesture.Move(10, -8, 0).ShouldBe(0);
        gesture.Advance(2_000).ShouldBe(0);
        gesture.Direction.ShouldBe(ArrowDirection.None);
    }

    [Fact]
    public void LeavingTheDeadZone_SendsOneKeyAtOnce_AndTheSlowSpeedWaitsBeforeRepeating()
    {
        var gesture = new ArrowGesture();

        gesture.Move(-30, 0, 1_000).ShouldBe(1);
        gesture.Direction.ShouldBe(ArrowDirection.Left);
        gesture.Speed.ShouldBe(1);

        // Held: nothing more until the first-repeat delay is up, then one per interval.
        gesture.Advance(1_000 + ArrowGesture.FirstRepeatDelayMs - 1).ShouldBe(0);
        gesture.Advance(1_000 + ArrowGesture.FirstRepeatDelayMs).ShouldBe(1);
        gesture.Advance(1_000 + ArrowGesture.FirstRepeatDelayMs + ArrowGesture.IntervalMs(1)).ShouldBe(1);
    }

    [Fact]
    public void DraggingFurtherTheSameWay_ShiftsThroughTheThreeSpeeds()
    {
        var gesture = new ArrowGesture();

        gesture.Move(0, -30, 0);
        gesture.Speed.ShouldBe(1);
        gesture.Direction.ShouldBe(ArrowDirection.Up);

        gesture.Move(0, -ArrowGesture.SecondSpeedAt, 10);
        gesture.Speed.ShouldBe(2);

        gesture.Move(0, -ArrowGesture.ThirdSpeedAt, 20);
        gesture.Speed.ShouldBe(3);

        // A second at the fastest speed is many keys; the same second at the slowest is a handful.
        var fast = 0;

        for (var t = 20L; t <= 1_020; t += 10)
        {
            fast += gesture.Advance(t);
        }

        var slow = new ArrowGesture();
        var slowCount = slow.Move(0, -30, 0);

        for (var t = 0L; t <= 1_000; t += 10)
        {
            slowCount += slow.Advance(t);
        }

        fast.ShouldBeGreaterThan(slowCount * 4);
    }

    [Fact]
    public void ASmallDriftOffTheAxis_DoesNotTurnLeftIntoUp()
    {
        var gesture = new ArrowGesture();

        gesture.Move(-40, 0, 0);
        gesture.Move(-40, -45, 10);

        gesture.Direction.ShouldBe(ArrowDirection.Left);

        // Clearly vertical now, past the hysteresis.
        gesture.Move(-20, -60, 20).ShouldBe(1);
        gesture.Direction.ShouldBe(ArrowDirection.Up);
    }

    [Fact]
    public void ComingBackToTheCentre_Stops()
    {
        var gesture = new ArrowGesture();

        gesture.Move(50, 0, 0);
        gesture.Move(3, 2, 10).ShouldBe(0);

        gesture.Direction.ShouldBe(ArrowDirection.None);
        gesture.Advance(5_000).ShouldBe(0);
    }

    // ── reading back the echo ────────────────────────────────────────────────────────────────────────────

    [Theory]
    [InlineData("\x1b[32mstan@box\x1b[0m:~$ ls -la", "stan@box:~$ ls -la")]
    [InlineData("old output\r\n$ git statsu\b \b\b \bus", "$ git status")]
    [InlineData("$ rm -rf build\r$ ls\x1b[K", "$ ls")]
    [InlineData("\x1b]0;stan@box: ~\a$ uptime", "$ uptime")]
    [InlineData("$ ech\x1b[1D\x1b[1@o", "$ ecoh")]
    public void TheCursorsLine_IsReadAsATerminalWouldDrawIt(string output, string expected) =>
        EchoedLine.LastLine(Ascii(output)).ShouldBe(expected);

    // ── the history ──────────────────────────────────────────────────────────────────────────────────────

    private RecentOutput Recent() => new(Ascii(screen), AlternateScreen: false);

    /// <summary>Types text one key at a time, echoing each key the way an ordinary shell prompt does.</summary>
    private void TypeEchoed(TypedCommandHistory history, string text)
    {
        foreach (var c in text)
        {
            history.Observe(1, "box", Ascii(c.ToString()), Recent);
            screen += c;
        }
    }

    [Fact]
    public void ACommandTheShellEchoed_IsKept()
    {
        var history = new TypedCommandHistory();

        TypeEchoed(history, "uptime");
        history.Observe(1, "box", "\r"u8, Recent);

        history.Entries.ShouldHaveSingleItem().ShouldBe(new HistoryEntry("uptime", "box"));
    }

    [Fact]
    public void APasswordTypedWithEchoOff_IsNeverKept()
    {
        var history = new TypedCommandHistory();
        screen = "[sudo] password for stan: ";

        // Typed, but nothing comes back: the prompt line is exactly what it was.
        foreach (var c in "hunter2")
        {
            history.Observe(1, "box", Ascii(c.ToString()), Recent);
        }

        history.Observe(1, "box", "\r"u8, Recent);

        history.Entries.ShouldBeEmpty();
    }

    [Fact]
    public void APasswordTypedAfterAnArrowKey_IsStillNeverKept()
    {
        var history = new TypedCommandHistory();
        screen = "Password: ";

        history.Observe(1, "box", "\x1b[D"u8, Recent);

        foreach (var c in "s3cret")
        {
            history.Observe(1, "box", Ascii(c.ToString()), Recent);
        }

        history.Observe(1, "box", "\r"u8, Recent);

        history.Entries.ShouldBeEmpty();
    }

    [Fact]
    public void APromptThatEchoesStars_IsNotACommand()
    {
        var history = new TypedCommandHistory();
        screen = "Passphrase: ";

        foreach (var c in "s3cret")
        {
            history.Observe(1, "box", Ascii(c.ToString()), Recent);
            screen += '*';
        }

        history.Observe(1, "box", "\r"u8, Recent);

        history.Entries.ShouldBeEmpty();
    }

    [Fact]
    public void ALineFinishedWithTab_IsKeptAsTheShellCompletedIt()
    {
        var history = new TypedCommandHistory();

        TypeEchoed(history, "cd /var/lo");
        history.Observe(1, "box", "\t"u8, Recent);
        screen += "g/";
        history.Observe(1, "box", "\r"u8, Recent);

        history.Entries.ShouldHaveSingleItem().Command.ShouldBe("cd /var/log/");
    }

    [Fact]
    public void NothingTypedIntoAFullScreenProgram_IsKept()
    {
        var history = new TypedCommandHistory();

        RecentOutput InVi() => new(Ascii("~\r\n~\r\nhello"), AlternateScreen: true);

        foreach (var c in "hello")
        {
            history.Observe(1, "box", Ascii(c.ToString()), InVi);
        }

        history.Observe(1, "box", "\r"u8, InVi);

        history.Entries.ShouldBeEmpty();
    }

    [Fact]
    public void RunningACommandAgain_MovesItToTheTopRatherThanListingItTwice()
    {
        var history = new TypedCommandHistory();

        foreach (var command in new[] { "ls", "df -h", "ls" })
        {
            screen = "$ ";
            TypeEchoed(history, command);
            history.Observe(1, "box", "\r"u8, Recent);
        }

        history.Entries.Select(e => e.Command).ShouldBe(["ls", "df -h"]);
    }

    [Fact]
    public void CtrlC_AbandonsTheLine()
    {
        var history = new TypedCommandHistory();

        TypeEchoed(history, "rm -rf /tmp/x");
        history.Observe(1, "box", "\x03"u8, Recent);
        screen = "stan@box:~$ ";
        history.Observe(1, "box", "\r"u8, Recent);

        history.Entries.ShouldBeEmpty();
    }

    // ── the view model ───────────────────────────────────────────────────────────────────────────────────

    private ClientSettingsStore Settings() => new(new ClientPaths(directory));

    private TerminalKeyboardViewModel Keyboard(ClientSettingsStore? store = null) =>
        new(
            store ?? Settings(),
            () => new TypingTarget(1, "box"),
            (_, bytes) =>
            {
                sent.Add(bytes.ToArray());
                return ValueTask.CompletedTask;
            },
            _ => Recent(),
            (_, _, _, _) => Task.FromResult(true),
            _ => Task.CompletedTask);

    private static KeyButtonViewModel Button(TerminalKeyboardViewModel keyboard, string id) =>
        keyboard.Groups.SelectMany(g => g.Keys).First(k => k.Key.Id == id);

    [Fact]
    public void CtrlOnTheBar_AppliesToTheNextLetterFromTheSoftKeyboard_AndThenLetsGo()
    {
        var keyboard = Keyboard();

        Button(keyboard, "ctrl").PressCommand.Execute(null);
        keyboard.IsControlLatched.ShouldBeTrue();
        Button(keyboard, "ctrl").IsLatched.ShouldBeTrue();

        keyboard.Send(Ascii("c"));
        keyboard.Send(Ascii("c"));

        sent.Select(Shown).ShouldBe(["\x03", "c"]);
        keyboard.IsControlLatched.ShouldBeFalse();
        Button(keyboard, "ctrl").IsLatched.ShouldBeFalse();
    }

    [Fact]
    public void TheBarAsShipped_IsTwoRows_ModifiersAboveCursorKeys()
    {
        var keyboard = Keyboard();

        keyboard.BarRows.Count.ShouldBe(2);
        keyboard.BarRows[0].Keys.Select(k => k.Label).ShouldBe(["esc", "tab", "ctrl", "alt", "|", "-", "/", "~"]);
        keyboard.BarRows[1].Keys.Select(k => k.Label).ShouldBe(["←", "↓", "↑", "→", "paste"]);
    }

    [Fact]
    public void ACustomisedBar_SurvivesARelaunch()
    {
        var store = Settings();
        var keyboard = Keyboard(store);

        keyboard.OpenCustomizeCommand.Execute(null);
        keyboard.BarEditor[1].MoveUpCommand.Execute(null);  // tab before esc
        keyboard.BarEditor.Single(r => r.Label == "paste").RemoveCommand.Execute(null);
        keyboard.NewKeyLabel = "wq";
        keyboard.NewKeySequence = @"\e:wq\r";
        keyboard.AddCustomKeyCommand.Execute(null);

        var relaunched = Keyboard(store);
        var labels = relaunched.BarRows.SelectMany(r => r.Keys).Select(k => k.Label).ToList();

        labels[0].ShouldBe("tab");
        labels[1].ShouldBe("esc");
        labels.ShouldNotContain("paste");
        labels[^1].ShouldBe("wq");
        relaunched.Groups.Last().Title.ShouldBe("YOUR KEYS");

        relaunched.BarRows.SelectMany(r => r.Keys).Last().PressCommand.Execute(null);
        Shown(sent.Last()).ShouldBe("\x1b:wq\r");
    }

    [Fact]
    public void AHiddenGroup_IsLeftOffTheKeysTab_AndStaysHidden()
    {
        var store = Settings();
        var keyboard = Keyboard(store);

        keyboard.GroupEditor.Single(g => g.Title == "TMUX").IsShown = false;

        keyboard.Groups.Select(g => g.Title).ShouldNotContain("TMUX");
        Keyboard(store).Groups.Select(g => g.Title).ShouldNotContain("TMUX");
    }

    [Fact]
    public void Reset_PutsTheBarBack_ButKeepsKeysSomebodyWrote()
    {
        var keyboard = Keyboard();

        keyboard.NewKeyLabel = "deploy";
        keyboard.NewKeySequence = "make deploy";
        keyboard.AddCustomKeyCommand.Execute(null);

        keyboard.ResetLayoutCommand.Execute(null);

        keyboard.BarRows.SelectMany(r => r.Keys).Select(k => k.Key.Id).ShouldBe(TerminalKeyCatalog.DefaultBar);
        keyboard.CustomKeyEditor.ShouldHaveSingleItem().Label.ShouldBe("deploy");
    }

    [Fact]
    public void AKeyWithANonsenseSequence_IsRefusedWithAReason()
    {
        var keyboard = Keyboard();

        keyboard.NewKeyLabel = "bad";
        keyboard.NewKeySequence = @"\x1";
        keyboard.AddCustomKeyCommand.Execute(null);

        keyboard.CustomKeyEditor.ShouldBeEmpty();
        keyboard.CustomizeStatus.ShouldNotBeNullOrEmpty();
    }

    [Fact]
    public void TheBarHoldsSixteenKeys_AndSaysSoWhenFull()
    {
        var keyboard = Keyboard();

        foreach (var choice in keyboard.GroupEditor.Single(g => g.Title == "FUNCTION").Keys.ToList())
        {
            // Rebuilt after every toggle, so look the chip up again each time.
            keyboard.GroupEditor.Single(g => g.Title == "FUNCTION").Keys
                .Single(k => k.Label == choice.Label).ToggleCommand.Execute(null);
        }

        keyboard.BarRows.Sum(r => r.Keys.Count).ShouldBe(TerminalKeyCatalog.MaximumBarKeys);
        keyboard.CanAddToBar.ShouldBeFalse();
        keyboard.CustomizeStatus.ShouldContain("16");
    }

    [Fact]
    public void TheQuickAccessKeyboard_ReopensToTheTabLastUsed()
    {
        var store = Settings();

        Keyboard(store).SelectTabCommand.Execute(QuickAccessTab.History);

        var relaunched = Keyboard(store);

        relaunched.SelectedTab.ShouldBe(QuickAccessTab.History);
        relaunched.IsHistoryTab.ShouldBeTrue();
    }

    [Fact]
    public void AnIdThisBuildDoesNotKnow_IsSkippedRatherThanRefused()
    {
        var store = Settings();
        store.Write(new ClientSettings(TerminalKeyboard: new TerminalKeyboardSettings(
            Bar: ["esc", "from-the-future", "up"],
            GroupOrder: ["vim", "nonsense"])));

        var keyboard = Keyboard(store);

        keyboard.BarRows.ShouldHaveSingleItem().Keys.Select(k => k.Key.Id).ShouldBe(["esc", "up"]);
        keyboard.Groups[0].Title.ShouldBe("VIM");
        keyboard.Groups.Count.ShouldBe(TerminalKeyCatalog.Groups.Count);
    }

    [Fact]
    public void TheGesturesArrows_IgnoreALatchedCtrl()
    {
        var keyboard = Keyboard();

        Button(keyboard, "ctrl").PressCommand.Execute(null);
        keyboard.SendArrow(ArrowDirection.Up, 2);

        Shown(sent.Single()).ShouldBe("\x1b[A\x1b[A");
        keyboard.IsControlLatched.ShouldBeTrue();
    }
}