using System.IO;
using System.Linq;
using AcDream.UI.Abstractions.Input;
using Silk.NET.Input;

namespace AcDream.UI.Abstractions.Tests.Input;

/// <summary>
/// K.1c: <see cref="KeyBindings.LoadOrDefault"/> /
/// <see cref="KeyBindings.SaveToFile"/> round-trip + version migration.
/// Pins schema-stable behavior so future K.1d / Phase L panel-binding
/// edits don't accidentally break existing user keymap files.
/// </summary>
public class KeyBindingsJsonTests
{
    private static string TempFile(string suffix = ".json")
    {
        var f = Path.Combine(Path.GetTempPath(),
            $"acdream_kb_test_{System.Guid.NewGuid():N}{suffix}");
        return f;
    }

    [Fact]
    public void LoadOrDefault_missing_file_returns_RetailDefaults()
    {
        var path = TempFile();
        // No file written.
        var loaded = KeyBindings.LoadOrDefault(path);
        var defaults = KeyBindings.RetailDefaults();
        Assert.Equal(defaults.All.Count, loaded.All.Count);
    }

    [Fact]
    public void Roundtrip_preserves_every_binding()
    {
        var path = TempFile();
        try
        {
            var original = KeyBindings.RetailDefaults();
            original.SaveToFile(path);

            var loaded = KeyBindings.LoadOrDefault(path);

            Assert.Equal(original.All.Count, loaded.All.Count);
            // Every binding from the original must round-trip with structural
            // equality (chord + action + activation).
            foreach (var b in original.All)
            {
                Assert.Contains(loaded.All, x =>
                    x.Chord == b.Chord
                    && x.Action == b.Action
                    && x.Activation == b.Activation);
            }
        }
        finally
        {
            if (File.Exists(path)) File.Delete(path);
        }
    }

    [Fact]
    public void LoadOrDefault_corrupt_file_returns_RetailDefaults()
    {
        var path = TempFile();
        try
        {
            File.WriteAllText(path, "{ this is not valid JSON :: garbage");

            var loaded = KeyBindings.LoadOrDefault(path);
            var defaults = KeyBindings.RetailDefaults();
            Assert.Equal(defaults.All.Count, loaded.All.Count);
        }
        finally
        {
            if (File.Exists(path)) File.Delete(path);
        }
    }

    [Fact]
    public void LoadOrDefault_corrupt_file_does_NOT_overwrite_user_file()
    {
        var path = TempFile();
        try
        {
            const string corrupt = "{ this is not valid JSON :: garbage";
            File.WriteAllText(path, corrupt);

            _ = KeyBindings.LoadOrDefault(path);

            // The corrupt file must remain untouched on disk so the user
            // can recover or hand-edit. We never silently blow it away.
            Assert.Equal(corrupt, File.ReadAllText(path));
        }
        finally
        {
            if (File.Exists(path)) File.Delete(path);
        }
    }

    [Fact]
    public void Custom_binding_for_one_action_keeps_defaults_for_others()
    {
        var path = TempFile();
        try
        {
            // User customizes ONE action — replace MovementForward with Q.
            var custom = new KeyBindings();
            custom.Add(new(new KeyChord(Key.Q, ModifierMask.None), InputAction.MovementForward));
            custom.SaveToFile(path);

            var loaded = KeyBindings.LoadOrDefault(path);

            // Custom: MovementForward → Q (only — the user's file
            // overrode all defaults for that action).
            var fwd = loaded.ForAction(InputAction.MovementForward).ToList();
            Assert.Single(fwd);
            Assert.Equal(new KeyChord(Key.Q, ModifierMask.None), fwd[0].Chord);

            // Default-merged: MovementBackup still has its retail bindings
            // because the user file didn't customize it.
            var back = loaded.ForAction(InputAction.MovementBackup).ToList();
            Assert.Contains(back, x => x.Chord == new KeyChord(Key.X, ModifierMask.None));
        }
        finally
        {
            if (File.Exists(path)) File.Delete(path);
        }
    }

    [Fact]
    public void LoadOrDefault_handles_version_zero_legacy_file()
    {
        // A pretend "old schema" file with version=0 + just one action.
        // Should still parse — unknown fields are ignored, missing
        // actions get default-merged.
        var path = TempFile();
        try
        {
            const string legacyJson = """
                {
                  "version": 0,
                  "actions": {
                    "MovementForward": [
                      { "key": "W", "mod": "None" }
                    ]
                  }
                }
                """;
            File.WriteAllText(path, legacyJson);

            var loaded = KeyBindings.LoadOrDefault(path);

            // The custom binding survives.
            var fwd = loaded.ForAction(InputAction.MovementForward).ToList();
            Assert.Single(fwd);

            // Default-merged: the user file didn't define MovementBackup
            // so it gets the retail default chords.
            var back = loaded.ForAction(InputAction.MovementBackup).ToList();
            Assert.NotEmpty(back);
        }
        finally
        {
            if (File.Exists(path)) File.Delete(path);
        }
    }

    [Fact]
    public void LoadOrDefault_preserves_Hold_activation()
    {
        var path = TempFile();
        try
        {
            var original = new KeyBindings();
            original.Add(new(
                new KeyChord(Key.ShiftLeft, ModifierMask.None),
                InputAction.MovementWalkMode,
                ActivationType.Hold));
            original.SaveToFile(path);

            var loaded = KeyBindings.LoadOrDefault(path);
            var binds = loaded.ForAction(InputAction.MovementWalkMode).ToList();
            // The user binding is preserved with Hold activation.
            Assert.Contains(binds, x =>
                x.Chord.Key == Key.ShiftLeft
                && x.Activation == ActivationType.Hold);
        }
        finally
        {
            if (File.Exists(path)) File.Delete(path);
        }
    }

    [Fact]
    public void LoadOrDefault_unknown_action_name_skipped_silently()
    {
        var path = TempFile();
        try
        {
            const string json = """
                {
                  "version": 1,
                  "actions": {
                    "NotARealActionName": [
                      { "key": "W", "mod": "None" }
                    ],
                    "MovementForward": [
                      { "key": "Q", "mod": "None" }
                    ]
                  }
                }
                """;
            File.WriteAllText(path, json);

            var loaded = KeyBindings.LoadOrDefault(path);
            // The known action loaded; unknown action skipped without
            // throwing.
            var fwd = loaded.ForAction(InputAction.MovementForward).ToList();
            Assert.Contains(fwd, x => x.Chord.Key == Key.Q);
        }
        finally
        {
            if (File.Exists(path)) File.Delete(path);
        }
    }

    [Fact]
    public void DefaultPath_lives_under_LocalAppData_acdream()
    {
        var path = KeyBindings.DefaultPath();
        Assert.Contains("acdream", path);
        Assert.EndsWith("keybinds.json", path);
    }
}