using SpaceGame.Api.Contracts;
using SpaceGame.Api.Simulation.AI;
using SpaceGame.Api.Simulation.Engine;
using SpaceGame.Api.Simulation.Model;
using static SpaceGame.Api.Simulation.Systems.InfrastructureSimulationService;
using static SpaceGame.Api.Simulation.Support.SimulationRuntimeSupport;

namespace SpaceGame.Api.Simulation.Systems;

internal sealed class ShipControlService
{
  private static readonly ShipBehaviorStateMachine _shipBehaviorStateMachine = ShipBehaviorStateMachine.CreateDefault();

  private static CommanderRuntime? GetShipCommander(SimulationWorld world, ShipRuntime ship) =>
      ship.CommanderId is null
          ? null
          : world.Commanders.FirstOrDefault(candidate => candidate.Id == ship.CommanderId && candidate.Kind == CommanderKind.Ship);

  private static void SyncCommanderToShip(ShipRuntime ship, CommanderRuntime commander)
  {
    if (commander.ActiveBehavior is not null)
    {
      ship.DefaultBehavior.Kind = commander.ActiveBehavior.Kind;
      ship.DefaultBehavior.AreaSystemId = commander.ActiveBehavior.AreaSystemId;
      ship.DefaultBehavior.ModuleId = commander.ActiveBehavior.ModuleId;
      ship.DefaultBehavior.NodeId = commander.ActiveBehavior.NodeId;
      ship.DefaultBehavior.Phase = commander.ActiveBehavior.Phase;
      ship.DefaultBehavior.PatrolIndex = commander.ActiveBehavior.PatrolIndex;
      ship.DefaultBehavior.StationId = commander.ActiveBehavior.StationId;
    }

    if (commander.ActiveOrder is null)
    {
      ship.Order = null;
    }
    else
    {
      ship.Order = new ShipOrderRuntime
      {
        Kind = commander.ActiveOrder.Kind,
        Status = commander.ActiveOrder.Status,
        DestinationSystemId = commander.ActiveOrder.DestinationSystemId,
        DestinationPosition = commander.ActiveOrder.DestinationPosition,
      };
    }

    if (commander.ActiveTask is not null)
    {
      ship.ControllerTask = new ControllerTaskRuntime
      {
        Kind = ParseControllerTaskKind(commander.ActiveTask.Kind),
        Status = commander.ActiveTask.Status,
        CommanderId = commander.Id,
        TargetEntityId = commander.ActiveTask.TargetEntityId,
        TargetNodeId = commander.ActiveTask.TargetNodeId,
        TargetPosition = commander.ActiveTask.TargetPosition,
        TargetSystemId = commander.ActiveTask.TargetSystemId,
        Threshold = commander.ActiveTask.Threshold,
      };
    }
  }

  private static void SyncShipToCommander(ShipRuntime ship, CommanderRuntime commander)
  {
    commander.ActiveBehavior ??= new CommanderBehaviorRuntime { Kind = ship.DefaultBehavior.Kind };
    commander.ActiveBehavior.Kind = ship.DefaultBehavior.Kind;
    commander.ActiveBehavior.AreaSystemId = ship.DefaultBehavior.AreaSystemId;
    commander.ActiveBehavior.ModuleId = ship.DefaultBehavior.ModuleId;
    commander.ActiveBehavior.NodeId = ship.DefaultBehavior.NodeId;
    commander.ActiveBehavior.Phase = ship.DefaultBehavior.Phase;
    commander.ActiveBehavior.PatrolIndex = ship.DefaultBehavior.PatrolIndex;
    commander.ActiveBehavior.StationId = ship.DefaultBehavior.StationId;

    if (ship.Order is null)
    {
      commander.ActiveOrder = null;
    }
    else
    {
      commander.ActiveOrder ??= new CommanderOrderRuntime
      {
        Kind = ship.Order.Kind,
        DestinationSystemId = ship.Order.DestinationSystemId,
        DestinationPosition = ship.Order.DestinationPosition,
      };
      commander.ActiveOrder.Status = ship.Order.Status;
      commander.ActiveOrder.TargetEntityId = ship.ControllerTask.TargetEntityId;
      commander.ActiveOrder.DestinationNodeId = ship.ControllerTask.TargetNodeId ?? ship.SpatialState.DestinationNodeId;
    }

    commander.ActiveTask ??= new CommanderTaskRuntime { Kind = ship.ControllerTask.Kind.ToContractValue() };
    commander.ActiveTask.Kind = ship.ControllerTask.Kind.ToContractValue();
    commander.ActiveTask.Status = ship.ControllerTask.Status;
    commander.ActiveTask.TargetEntityId = ship.ControllerTask.TargetEntityId;
    commander.ActiveTask.TargetNodeId = ship.ControllerTask.TargetNodeId;
    commander.ActiveTask.TargetPosition = ship.ControllerTask.TargetPosition;
    commander.ActiveTask.TargetSystemId = ship.ControllerTask.TargetSystemId;
    commander.ActiveTask.Threshold = ship.ControllerTask.Threshold;
  }

  internal void RefreshControlLayers(ShipRuntime ship, SimulationWorld world)
  {
    var commander = GetShipCommander(world, ship);
    if (commander is not null)
    {
      SyncCommanderToShip(ship, commander);
    }

    if (ship.Order is not null && ship.Order.Status == OrderStatus.Queued)
    {
      ship.Order.Status = OrderStatus.Accepted;
      if (commander?.ActiveOrder is not null)
      {
        commander.ActiveOrder.Status = ship.Order.Status;
      }
    }

    if (commander is not null)
    {
      SyncShipToCommander(ship, commander);
    }
  }

  internal void PlanControllerTask(SimulationEngine engine, ShipRuntime ship, SimulationWorld world)
  {
    var commander = GetShipCommander(world, ship);
    if (ship.Order is not null)
    {
      ship.ControllerTask = new ControllerTaskRuntime
      {
        Kind = ControllerTaskKind.Travel,
        Status = WorkStatus.Active,
        CommanderId = commander?.Id,
        TargetSystemId = ship.Order.DestinationSystemId,
        TargetNodeId = ship.SpatialState.DestinationNodeId,
        TargetPosition = ship.Order.DestinationPosition,
        Threshold = world.Balance.ArrivalThreshold,
      };
      SyncCommanderTask(commander, ship.ControllerTask);
      return;
    }

    _shipBehaviorStateMachine.Plan(engine, ship, world);
    SyncCommanderTask(commander, ship.ControllerTask);
  }

  internal void PlanResourceHarvest(ShipRuntime ship, SimulationWorld world, string resourceItemId, string requiredModule)
  {
    var behavior = ship.DefaultBehavior;
    var refinery = SelectBestBuyStation(world, ship, resourceItemId, behavior.StationId);
    behavior.StationId = refinery?.Id;
    var node = behavior.NodeId is null
        ? world.Nodes
            .Where(candidate =>
                (behavior.AreaSystemId is null || candidate.SystemId == behavior.AreaSystemId) &&
                candidate.ItemId == resourceItemId &&
                candidate.OreRemaining > 0.01f)
            .OrderByDescending(candidate => candidate.OreRemaining)
            .FirstOrDefault()
        : world.Nodes.FirstOrDefault(candidate => candidate.Id == behavior.NodeId && candidate.OreRemaining > 0.01f);

    if (refinery is null || node is null || !HasShipCapabilities(ship.Definition, requiredModule))
    {
      behavior.Kind = "idle";
      ship.ControllerTask = CreateIdleTask(world.Balance.ArrivalThreshold);
      return;
    }

    behavior.NodeId ??= node.Id;

    if (GetShipCargoAmount(ship) >= ship.Definition.CargoCapacity - 0.01f
        && behavior.Phase is "travel-to-node" or "extract")
    {
      behavior.Phase = "travel-to-station";
    }

    if (ship.DockedStationId == refinery.Id)
    {
      if (GetShipCargoAmount(ship) > 0.01f)
      {
        behavior.Phase = "unload";
      }
      else if (behavior.Phase is "dock" or "unload")
      {
        behavior.Phase = "undock";
      }
    }
    else if (behavior.Phase is not "travel-to-station" and not "dock" and not "travel-to-node" and not "extract")
    {
      behavior.Phase = "travel-to-station";
    }

    switch (behavior.Phase)
    {
      case "extract":
        var extractionPosition = GetResourceHoldPosition(node.Position, ship.Id, 20f);
        ship.ControllerTask = new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.Extract,
          TargetEntityId = node.Id,
          TargetSystemId = node.SystemId,
          TargetPosition = extractionPosition,
          Threshold = 5f,
        };
        break;
      case "travel-to-station":
        ship.ControllerTask = new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.Travel,
          TargetEntityId = refinery.Id,
          TargetSystemId = refinery.SystemId,
          TargetPosition = refinery.Position,
          Threshold = refinery.Radius + 8f,
        };
        break;
      case "dock":
        ship.ControllerTask = new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.Dock,
          TargetEntityId = refinery.Id,
          TargetSystemId = refinery.SystemId,
          TargetPosition = refinery.Position,
          Threshold = refinery.Radius + 4f,
        };
        break;
      case "unload":
        ship.ControllerTask = new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.Unload,
          TargetEntityId = refinery.Id,
          TargetSystemId = refinery.SystemId,
          TargetPosition = refinery.Position,
          Threshold = 0f,
        };
        break;
      case "undock":
        ship.ControllerTask = new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.Undock,
          TargetEntityId = refinery.Id,
          TargetSystemId = refinery.SystemId,
          TargetPosition = new Vector3(refinery.Position.X + world.Balance.UndockDistance, refinery.Position.Y, refinery.Position.Z),
          Threshold = 8f,
        };
        break;
      default:
        ship.ControllerTask = new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.Travel,
          TargetEntityId = node.Id,
          TargetSystemId = node.SystemId,
          TargetPosition = node.Position,
          Threshold = 18f,
        };
        behavior.Phase = "travel-to-node";
        break;
    }
  }

  internal static StationRuntime? SelectBestBuyStation(SimulationWorld world, ShipRuntime ship, string itemId, string? preferredStationId)
  {
    var preferred = preferredStationId is null
        ? null
        : world.Stations.FirstOrDefault(station => station.Id == preferredStationId);

    var bestOrder = world.MarketOrders
        .Where(order =>
            order.Kind == MarketOrderKinds.Buy &&
            order.ConstructionSiteId is null &&
            order.State != MarketOrderStateKinds.Cancelled &&
            order.ItemId == itemId &&
            order.RemainingAmount > 0.01f)
        .Select(order => (Order: order, Station: world.Stations.FirstOrDefault(station => station.Id == order.StationId)))
        .Where(entry => entry.Station is not null)
        .OrderByDescending(entry =>
        {
          var distancePenalty = entry.Station!.SystemId == ship.SystemId ? 0f : 0.2f;
          return entry.Order.Valuation - distancePenalty;
        })
        .FirstOrDefault();

    return bestOrder.Station ?? preferred;
  }

  private static ControllerTaskRuntime CreateStationSupportTask(SimulationWorld world, ShipRuntime ship, StationRuntime station, string? phase) =>
      phase switch
      {
        "dock" => new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.Dock,
          TargetEntityId = station.Id,
          TargetSystemId = station.SystemId,
          TargetPosition = station.Position,
          Threshold = 8f,
        },
        "load" => new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.Load,
          TargetEntityId = station.Id,
          TargetSystemId = station.SystemId,
          TargetPosition = station.Position,
          Threshold = 8f,
        },
        "unload" => new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.Unload,
          TargetEntityId = station.Id,
          TargetSystemId = station.SystemId,
          TargetPosition = station.Position,
          Threshold = 8f,
        },
        "undock" => new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.Undock,
          TargetEntityId = station.Id,
          TargetSystemId = station.SystemId,
          TargetPosition = new Vector3(station.Position.X + world.Balance.UndockDistance, station.Position.Y, station.Position.Z),
          Threshold = 8f,
        },
        _ => CreateIdleTask(world.Balance.ArrivalThreshold),
      };

  internal void PlanStationConstruction(ShipRuntime ship, SimulationWorld world)
  {
    var behavior = ship.DefaultBehavior;
    var station = world.Stations.FirstOrDefault(candidate => candidate.Id == behavior.StationId);
    var site = station is null ? null : GetConstructionSiteForStation(world, station.Id);
    if (station is null)
    {
      behavior.Kind = "idle";
      ship.ControllerTask = CreateIdleTask(world.Balance.ArrivalThreshold);
      return;
    }

    var moduleId = site?.BlueprintId ?? GetNextStationModuleToBuild(station, world);
    behavior.ModuleId = moduleId;
    if (moduleId is null)
    {
      ship.ControllerTask = CreateIdleTask(world.Balance.ArrivalThreshold);
      return;
    }

    if (ship.DockedStationId is not null)
    {
      var dockedStation = world.Stations.FirstOrDefault(candidate => candidate.Id == ship.DockedStationId);
      if (dockedStation is not null)
      {
        dockedStation.DockedShipIds.Remove(ship.Id);
        ReleaseDockingPad(dockedStation, ship.Id);
      }

      ship.DockedStationId = null;
      ship.AssignedDockingPadIndex = null;
      ship.Position = GetConstructionHoldPosition(station, ship.Id);
      ship.TargetPosition = ship.Position;
    }

    var constructionHoldPosition = GetConstructionHoldPosition(station, ship.Id);
    var isAtConstructionHold = ship.SystemId == station.SystemId
        && ship.Position.DistanceTo(constructionHoldPosition) <= 10f;

    if (isAtConstructionHold)
    {
      if (site is not null && site.State == ConstructionSiteStateKinds.Active && !IsConstructionSiteReady(world, site))
      {
        behavior.Phase = "deliver-to-site";
      }
      else if (site is not null && site.State == ConstructionSiteStateKinds.Active && IsConstructionSiteReady(world, site))
      {
        behavior.Phase = "build-site";
      }
      else if (site is not null)
      {
        behavior.Phase = "wait-for-materials";
      }
      else if (CanStartModuleConstruction(station, world.ModuleRecipes[moduleId]))
      {
        behavior.Phase = "construct-module";
      }
      else
      {
        behavior.Phase = "wait-for-materials";
      }
    }
    else if (behavior.Phase != "travel-to-station")
    {
      behavior.Phase = "travel-to-station";
    }

    switch (behavior.Phase)
    {
      case "construct-module":
        ship.ControllerTask = new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.ConstructModule,
          TargetEntityId = station.Id,
          TargetSystemId = station.SystemId,
          TargetPosition = constructionHoldPosition,
          Threshold = 10f,
        };
        break;
      case "deliver-to-site":
        ship.ControllerTask = new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.DeliverConstruction,
          TargetEntityId = site?.Id,
          TargetSystemId = station.SystemId,
          TargetPosition = constructionHoldPosition,
          Threshold = 10f,
        };
        break;
      case "build-site":
        ship.ControllerTask = new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.BuildConstructionSite,
          TargetEntityId = site?.Id,
          TargetSystemId = station.SystemId,
          TargetPosition = constructionHoldPosition,
          Threshold = 10f,
        };
        break;
      case "wait-for-materials":
        ship.ControllerTask = new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.Idle,
          TargetEntityId = station.Id,
          TargetSystemId = station.SystemId,
          TargetPosition = constructionHoldPosition,
          Threshold = 0f,
        };
        break;
      default:
        ship.ControllerTask = new ControllerTaskRuntime
        {
          Kind = ControllerTaskKind.Travel,
          TargetEntityId = station.Id,
          TargetSystemId = station.SystemId,
          TargetPosition = constructionHoldPosition,
          Threshold = 10f,
        };
        behavior.Phase = "travel-to-station";
        break;
    }
  }

  internal void AdvanceControlState(SimulationEngine engine, ShipRuntime ship, SimulationWorld world, string controllerEvent)
  {
    var commander = GetShipCommander(world, ship);
    if (ship.Order is not null && controllerEvent == "arrived")
    {
      ship.Order = null;
      ship.ControllerTask.Kind = ControllerTaskKind.Idle;
      if (commander is not null)
      {
        commander.ActiveOrder = null;
        commander.ActiveTask = new CommanderTaskRuntime
        {
          Kind = ShipTaskKinds.Idle,
          Status = WorkStatus.Completed,
          TargetSystemId = ship.SystemId,
          Threshold = 0f,
        };
      }

      return;
    }

    _shipBehaviorStateMachine.ApplyEvent(engine, ship, world, controllerEvent);
    if (commander is not null)
    {
      SyncShipToCommander(ship, commander);
      if (commander.ActiveTask is not null)
      {
        commander.ActiveTask.Status = controllerEvent == "none" ? WorkStatus.Active : WorkStatus.Completed;
      }
    }
  }

  internal void TrackHistory(ShipRuntime ship, string controllerEvent)
  {
    var signature = $"{ship.State.ToContractValue()}|{ship.DefaultBehavior.Kind}|{ship.ControllerTask.Kind.ToContractValue()}|{ship.ControllerTask.TargetSystemId}|{ship.ControllerTask.TargetEntityId}|{GetShipCargoAmount(ship):0.0}|{controllerEvent}";
    if (signature == ship.LastSignature)
    {
      return;
    }

    ship.LastSignature = signature;
    var target = ship.ControllerTask.TargetEntityId
        ?? ship.ControllerTask.TargetSystemId
        ?? "none";
    var eventSummary = controllerEvent == "none" ? string.Empty : $" event={controllerEvent}";
    ship.History.Add($"{DateTimeOffset.UtcNow:HH:mm:ss}  state={ship.State.ToContractValue()} behavior={ship.DefaultBehavior.Kind} task={ship.ControllerTask.Kind.ToContractValue()} target={target} cargo={GetShipCargoAmount(ship):0.#}{eventSummary}");
    if (ship.History.Count > 18)
    {
      ship.History.RemoveAt(0);
    }
  }

  internal void EmitShipStateEvents(
      ShipRuntime ship,
      ShipState previousState,
      string previousBehavior,
      ControllerTaskKind previousTask,
      string controllerEvent,
      ICollection<SimulationEventRecord> events)
  {
    var occurredAtUtc = DateTimeOffset.UtcNow;

    if (previousState != ship.State)
    {
      events.Add(new SimulationEventRecord("ship", ship.Id, "state-changed", $"{ship.Definition.Label} {previousState.ToContractValue()} -> {ship.State.ToContractValue()}", occurredAtUtc));
    }

    if (previousBehavior != ship.DefaultBehavior.Kind)
    {
      events.Add(new SimulationEventRecord("ship", ship.Id, "behavior-changed", $"{ship.Definition.Label} behavior {previousBehavior} -> {ship.DefaultBehavior.Kind}", occurredAtUtc));
    }

    if (previousTask != ship.ControllerTask.Kind)
    {
      events.Add(new SimulationEventRecord("ship", ship.Id, "task-changed", $"{ship.Definition.Label} task {previousTask.ToContractValue()} -> {ship.ControllerTask.Kind.ToContractValue()}", occurredAtUtc));
    }

    if (controllerEvent != "none")
    {
      events.Add(new SimulationEventRecord("ship", ship.Id, controllerEvent, $"{ship.Definition.Label} {controllerEvent}", occurredAtUtc));
    }
  }

  internal static ControllerTaskRuntime CreateIdleTask(float threshold) =>
      new()
      {
        Kind = ControllerTaskKind.Idle,
        Threshold = threshold,
      };

  private static ControllerTaskKind ParseControllerTaskKind(string kind) => kind switch
  {
    "travel" => ControllerTaskKind.Travel,
    "extract" => ControllerTaskKind.Extract,
    "dock" => ControllerTaskKind.Dock,
    "load" => ControllerTaskKind.Load,
    "unload" => ControllerTaskKind.Unload,
    "deliver-construction" => ControllerTaskKind.DeliverConstruction,
    "build-construction-site" => ControllerTaskKind.BuildConstructionSite,

    "construct-module" => ControllerTaskKind.ConstructModule,
    "undock" => ControllerTaskKind.Undock,
    _ => ControllerTaskKind.Idle,
  };

  private static void SyncCommanderTask(CommanderRuntime? commander, ControllerTaskRuntime task)
  {
    if (commander is null)
    {
      return;
    }

    commander.ActiveTask = new CommanderTaskRuntime
    {
      Kind = task.Kind.ToContractValue(),
      Status = task.Status,
      TargetEntityId = task.TargetEntityId,
      TargetNodeId = task.TargetNodeId,
      TargetPosition = task.TargetPosition,
      TargetSystemId = task.TargetSystemId,
      Threshold = task.Threshold,
    };
  }
}