import { CreateAssetCommand } from '../src/core/commands/assetCommands';
import { CommandStack } from '../src/core/commands/CommandStack';
import { AddNodeCommand, ConnectCommand } from '../src/core/commands/graphCommands';
import { PlaceAssetCommand } from '../src/core/commands/sceneObjectCommands';
import { AddVariableCommand } from '../src/core/commands/variableCommands';
import {
  ENTITY_HANDLE,
  type EntityHandle,
  type GraphNode,
  type NodeContext,
  type PointerState,
  type Value,
  requireNodeDef,
} from '../src/core/graph';
import type { BehaviorAsset, SceneAsset } from '../src/core/model/Asset';
import { findObject, worldPosition } from '../src/core/model/hierarchy';
import { resolvedHolder } from '../src/core/model/instance';
import type { Position, PropertyBag, Vec2 } from '../src/core/model/Properties';
import { createEmptyProject, findScene, type Project } from '../src/core/model/Project';
import type { SceneObject } from '../src/core/model/SceneObject';
import { deserializeProject, serializeProject } from '../src/core/store/serialize';
import { BehaviorSystem } from '../src/runtime/systems/BehaviorSystem';
import { CollisionSystem } from '../src/runtime/systems/CollisionSystem';
import { Input } from '../src/runtime/systems/Input';
import { World } from '../src/runtime/World';

export interface ProjectFixture {
  project: Project;
  stack: CommandStack;
}

export interface SceneFixture extends ProjectFixture {
  sceneId: string;
  spriteId: string;
  /** The scene asset, looked up fresh (undo may replace it). */
  sceneOf(): SceneAsset;
  /** The scene with the content of placed containers resolved in – what the editor shows. */
  viewOf(): SceneAsset;
  object(id: string): SceneObject;
  /** World position of a scene object, ancestors included. */
  world(id: string): Position;
}

/** An empty project with an undo stack. */
export function makeProject(): ProjectFixture {
  const project = createEmptyProject('p', 'P');
  return { project, stack: new CommandStack(project) };
}

/** A project with a scene "Level" and a 100×100 sprite (named "Box" unless told otherwise), plus lookups into the scene. */
export function makeSpriteScene(spriteName = 'Box'): SceneFixture {
  const fixture = makeProject();
  const scene = new CreateAssetCommand('scene', 'Level');
  const sprite = new CreateAssetCommand('sprite', spriteName);
  fixture.stack.execute(scene);
  fixture.stack.execute(sprite);
  const sceneOf = () => findScene(fixture.project, scene.asset.id)!;
  const viewOf = () => resolvedHolder(fixture.project, sceneOf()) as SceneAsset;
  const object = (id: string) => findObject(viewOf(), id)!;
  return {
    ...fixture,
    sceneId: scene.asset.id,
    spriteId: sprite.asset.id,
    sceneOf,
    viewOf,
    object,
    world: (id) => worldPosition(viewOf(), object(id)),
  };
}

/** Places an asset into the fixture's scene at a world position (optionally below a parent) and returns the new object's id. */
export function place(
  fixture: SceneFixture,
  assetId: string,
  position: Vec2 | Position,
  parentId = '',
): string {
  const command = new PlaceAssetCommand(fixture.sceneId, assetId, position, parentId);
  fixture.stack.execute(command);
  return command.objectId;
}

/** Adds a behavior asset declaring the given number variables. */
export function makeBehavior(
  fixture: ProjectFixture,
  name = 'B',
  variables: readonly string[] = [],
): BehaviorAsset {
  const command = new CreateAssetCommand('behavior', name);
  fixture.stack.execute(command);
  for (const key of variables) fixture.stack.execute(new AddVariableCommand(command.asset.id, key, 'number'));
  return command.asset as BehaviorAsset;
}

export type Edge = readonly [from: GraphNode, fromPort: string, to: GraphNode, toPort: string];

export interface GraphEditor {
  /** Adds a node with inline params (graph coordinates do not matter to tests). */
  addNode(type: string, params?: PropertyBag): GraphNode;
  connect(from: GraphNode, fromPort: string, to: GraphNode, toPort: string): void;
  wire(edges: readonly Edge[]): void;
}

/** Command-driven editing of one behavior's graph, the way the editor does it. */
export function graphEditor(fixture: ProjectFixture, behavior: BehaviorAsset): GraphEditor {
  const { stack } = fixture;
  const connect: GraphEditor['connect'] = (from, fromPort, to, toPort) => {
    stack.execute(
      new ConnectCommand(behavior.id, { node: from.id, port: fromPort }, { node: to.id, port: toPort }),
    );
  };
  return {
    addNode(type, params = {}) {
      const command = new AddNodeCommand(behavior.id, type, 0, 0, params);
      stack.execute(command);
      return command.node;
    },
    connect,
    wire(edges) {
      for (const [from, fromPort, to, toPort] of edges) connect(from, fromPort, to, toPort);
    },
  };
}

export const NO_POINTER: PointerState = {
  x: 0,
  y: 0,
  inside: false,
  down: false,
  pressed: false,
  released: false,
};

/** A top-level entity handle named after itself, with empty props. */
export function fakeEntity(name: string, x = 0, assetId = `asset-${name}`): EntityHandle {
  return { [ENTITY_HANDLE]: true, id: name, assetId, name, x, y: 0, z: 0, props: {}, parent: null };
}

/** An entity handle "h" carrying the given props, optionally below a parent. */
export function fakeHandle(props: PropertyBag, parent: EntityHandle | null = null): EntityHandle {
  return { [ENTITY_HANDLE]: true, id: 'h', assetId: 'a', name: 'h', x: 0, y: 0, z: 0, props, parent };
}

export type FakeContext = NodeContext & { logs: string[]; stopped: boolean };

/** A NodeContext double: self/owner handles, `speed = 100`, dt 0.5, moves applied directly, `log` and `stop` recorded. */
export function fakeContext(overrides: Partial<NodeContext> = {}): FakeContext {
  const logs: string[] = [];
  const ctx: FakeContext = {
    self: fakeEntity('self'),
    owner: fakeEntity('owner'),
    variables: { speed: 100 },
    time: 0,
    dt: 0.5,
    logs,
    stopped: false,
    findByName: () => null,
    isKeyDown: () => false,
    pointer: { ...NO_POINTER },
    hitTest: () => false,
    isTouching: () => false,
    moveAndSlide: (target, dx, dy) => {
      target.x += dx;
      target.y += dy;
      return { blockedX: false, blockedY: false };
    },
    log: (message) => logs.push(message),
    spawn: () => null,
    destroy: () => {},
    stop: () => {
      ctx.stopped = true;
    },
    restart: () => {},
    ...overrides,
  };
  return ctx;
}

/** Runs one node definition in isolation and returns its data outputs. */
export function runNode(
  type: string,
  inputs: Record<string, Value>,
  params: PropertyBag = {},
  ctx: NodeContext = fakeContext(),
): Record<string, Value> {
  return requireNodeDef(type).run!(ctx, inputs, params).outputs ?? {};
}

export interface WorldOptions {
  collisions?: boolean;
  behaviors?: boolean;
}

export interface StartedWorld {
  world: World;
  collisions: CollisionSystem | null;
  /** Feed keys with `input.press('a')`; `frame()` clears the edges the way the editor does. */
  input: Input;
  /** One tick plus the end-of-frame bookkeeping the editor's play loop performs. */
  frame(dt?: number): void;
}

/** Instantiates the fixture's scene, optionally with a CollisionSystem and a BehaviorSystem (fed by those collisions). */
export function startWorld(
  fixture: SceneFixture,
  options: WorldOptions & { collisions: true },
): StartedWorld & { collisions: CollisionSystem };
export function startWorld(fixture: SceneFixture, options?: WorldOptions): StartedWorld;
export function startWorld(fixture: SceneFixture, options: WorldOptions = {}): StartedWorld {
  const world = World.instantiate(fixture.project, fixture.sceneId);
  const collisions = options.collisions ? new CollisionSystem() : null;
  const input = new Input();
  if (collisions) world.addSystem(collisions);
  if (options.behaviors) world.addSystem(new BehaviorSystem(fixture.project, input, collisions));
  return {
    world,
    collisions,
    input,
    frame(dt = 1 / 60) {
      world.tick(dt);
      input.endFrame();
    },
  };
}

/** The project as it comes back after being saved and loaded again. */
export function roundTrip(project: Project): Project {
  return deserializeProject(serializeProject(project));
}