using NeonSprawl.Server.Game.PositionState;

namespace NeonSprawl.Server.Game.Factions;

/// <summary>Maps <c>GET /game/players/{{id}}/faction-standing</c> — read snapshot (NEO-139).</summary>
public static class FactionStandingApi
{
    public static WebApplication MapFactionStandingApi(this WebApplication app)
    {
        app.MapGet(
            "/game/players/{id}/faction-standing",
            (string id, IPositionStateStore positions, IFactionDefinitionRegistry factionRegistry,
                IFactionStandingStore standingStore) =>
            {
                var trimmedId = id.Trim();
                if (trimmedId.Length == 0 || !positions.TryGetPosition(trimmedId, out _))
                {
                    return Results.NotFound();
                }

                var snapshotResult = TryBuildSnapshot(trimmedId, factionRegistry, standingStore);
                return snapshotResult.Kind switch
                {
                    FactionStandingSnapshotBuildKind.Success => Results.Json(snapshotResult.Response),
                    FactionStandingSnapshotBuildKind.StoreReadFailed =>
                        Results.Problem(
                            statusCode: StatusCodes.Status500InternalServerError,
                            title: "Faction standing read failed",
                            detail: snapshotResult.ReasonCode),
                    _ => throw new InvalidOperationException($"Unexpected build outcome: {snapshotResult.Kind}"),
                };
            });

        return app;
    }

    internal static FactionStandingSnapshotResponse BuildSnapshot(
        string playerId,
        IFactionDefinitionRegistry factionRegistry,
        IFactionStandingStore standingStore)
    {
        var result = TryBuildSnapshot(playerId, factionRegistry, standingStore);
        if (result.Kind != FactionStandingSnapshotBuildKind.Success || result.Response is null)
        {
            throw new InvalidOperationException(
                $"BuildSnapshot failed: {result.ReasonCode ?? result.Kind.ToString()}");
        }

        return result.Response;
    }

    private static FactionStandingSnapshotBuildResult TryBuildSnapshot(
        string playerId,
        IFactionDefinitionRegistry factionRegistry,
        IFactionStandingStore standingStore)
    {
        var defs = factionRegistry.GetDefinitionsInIdOrder();
        var factions = new List<FactionStandingRowJson>(defs.Count);
        foreach (var definition in defs)
        {
            var outcome = standingStore.TryGetStanding(playerId, definition.Id);
            if (!outcome.Success)
            {
                return new FactionStandingSnapshotBuildResult(
                    FactionStandingSnapshotBuildKind.StoreReadFailed,
                    null,
                    outcome.ReasonCode);
            }

            factions.Add(
                new FactionStandingRowJson
                {
                    Id = definition.Id,
                    Standing = outcome.Standing,
                });
        }

        return new FactionStandingSnapshotBuildResult(
            FactionStandingSnapshotBuildKind.Success,
            new FactionStandingSnapshotResponse
            {
                PlayerId = playerId,
                Factions = factions,
                SchemaVersion = FactionStandingSnapshotResponse.CurrentSchemaVersion,
            },
            null);
    }

    private enum FactionStandingSnapshotBuildKind
    {
        Success,
        StoreReadFailed,
    }

    private readonly record struct FactionStandingSnapshotBuildResult(
        FactionStandingSnapshotBuildKind Kind,
        FactionStandingSnapshotResponse? Response,
        string? ReasonCode);
}