/**
 * 그립 편집 도구 — 선택 도구에서 그립을 집으면 켜진다.
 * 클릭 한 번으로 그 그립을 옮긴다 (AutoCAD처럼 끌지 않고 집어서 놓는 방식).
 */
import type { Point } from '@flatten-js/core';
import { Actor, assign, createMachine } from 'xstate';
import type { Entity } from '../entities/Entity';
import { getPointFromEvent } from '../helpers/get-point-from-event';
import { type Grip, applyGrip } from '../helpers/grips';
import {
	getEntities,
	setActiveToolActor,
	setAngleGuideOriginPoint,
	setEntities,
	setGhostHelperEntities,
	setShouldDrawHelpers,
} from '../state';
import { Tool } from '../tools';
import { selectToolStateMachine } from './select-tool';
import { ActorEvent, type PointInputEvent, type StateEvent, type ToolContext } from './tool.types';

let editedEntity: Entity | null = null;
let editedGrip: Grip | null = null;

/** 선택 도구가 그립을 집었을 때 부른다 */
export function startGripEdit(entity: Entity, grip: Grip): void {
	editedEntity = entity;
	editedGrip = grip;
	setActiveToolActor(new Actor(gripEditToolStateMachine));
}

/** 편집 중인 객체 — 그립을 그릴 때 원본 대신 미리보기를 보여주려고 읽는다 */
export const getGripEditTargetId = (): string | null => editedEntity?.id ?? null;

function previewAt(point: Point): Entity | null {
	if (!editedEntity || !editedGrip) return null;
	return applyGrip(editedEntity, editedGrip, point);
}

export enum GripEditState {
	INIT = 'INIT',
	WAITING_FOR_TARGET_POINT = 'WAITING_FOR_TARGET_POINT',
}

export enum GripEditAction {
	INIT_GRIP_EDIT_TOOL = 'INIT_GRIP_EDIT_TOOL',
	DRAW_TEMP_GRIP_EDIT = 'DRAW_TEMP_GRIP_EDIT',
	APPLY_GRIP_EDIT = 'APPLY_GRIP_EDIT',
	SWITCH_TO_SELECT_TOOL = 'SWITCH_TO_SELECT_TOOL',
}

export const gripEditToolStateMachine = createMachine(
	{
		types: {} as { context: ToolContext; events: StateEvent },
		context: { type: Tool.GRIP_EDIT },
		initial: GripEditState.INIT,
		states: {
			[GripEditState.INIT]: {
				always: {
					actions: GripEditAction.INIT_GRIP_EDIT_TOOL,
					target: GripEditState.WAITING_FOR_TARGET_POINT,
				},
			},
			[GripEditState.WAITING_FOR_TARGET_POINT]: {
				description: '그립을 옮길 위치를 지정한다',
				meta: { instructions: '그립을 옮길 위치를 지정하십시오' },
				on: {
					[ActorEvent.DRAW]: { actions: GripEditAction.DRAW_TEMP_GRIP_EDIT },
					[ActorEvent.MOUSE_CLICK]: {
						actions: [GripEditAction.APPLY_GRIP_EDIT, GripEditAction.SWITCH_TO_SELECT_TOOL],
					},
					[ActorEvent.ABSOLUTE_POINT_INPUT]: {
						actions: [GripEditAction.APPLY_GRIP_EDIT, GripEditAction.SWITCH_TO_SELECT_TOOL],
					},
					[ActorEvent.RELATIVE_POINT_INPUT]: {
						actions: [GripEditAction.APPLY_GRIP_EDIT, GripEditAction.SWITCH_TO_SELECT_TOOL],
					},
					[ActorEvent.ESC]: { actions: GripEditAction.SWITCH_TO_SELECT_TOOL },
				},
			},
		},
	},
	{
		actions: {
			[GripEditAction.INIT_GRIP_EDIT_TOOL]: assign(() => {
				setShouldDrawHelpers(true);
				setGhostHelperEntities([]);
				setAngleGuideOriginPoint(editedGrip?.point ?? null);
				return {};
			}),
			[GripEditAction.DRAW_TEMP_GRIP_EDIT]: ({ event }) => {
				const point = getPointFromEvent(editedGrip?.point ?? null, event as PointInputEvent);
				const preview = previewAt(point);
				setGhostHelperEntities(preview ? [preview] : []);
			},
			[GripEditAction.APPLY_GRIP_EDIT]: ({ event }) => {
				const point = getPointFromEvent(editedGrip?.point ?? null, event as PointInputEvent);
				const edited = previewAt(point);
				if (!edited || !editedEntity) return;
				const targetId = editedEntity.id;
				setEntities(
					getEntities().map((entity) => (entity.id === targetId ? edited : entity)),
					true
				);
			},
			[GripEditAction.SWITCH_TO_SELECT_TOOL]: () => {
				editedEntity = null;
				editedGrip = null;
				setGhostHelperEntities([]);
				setAngleGuideOriginPoint(null);
				setActiveToolActor(new Actor(selectToolStateMachine));
			},
		},
	}
);