/**
 * OFFSET(337 설계 1-2) — 오토캐드 간격띄우기 차례: 거리(또는 통과점(T) · 지우기(E)) → 객체 → 면의 점 →
 * 객체로 되풀이 · 다중(M) = 방금 만든 것을 같은 거리로 되풀이 · U = 이 명령 안 마지막 하나 · 빈 Enter · Esc = 끝.
 * 거리 기억 = OFFSETDIST(처음 <통과점>) · 원본 지우기 기억 = OFFSETERASE.
 */
import { type Point, Segment } from '@flatten-js/core';
import { toast } from 'react-toastify';
import { assign, createMachine } from 'xstate';
import { OPT, type OptionSpec, type PromptSpec, recall, remember } from '../../commands/prompt';
import type { Entity } from '../../entities/Entity';
import { findClosestEntity } from '../../helpers/find-closest-entity';
import { getPointFromEvent } from '../../helpers/get-point-from-event';
import {
	addEntities,
	deleteEntities,
	getEntities,
	setAngleGuideOriginPoint,
	setGhostHelperEntities,
	setShouldDrawHelpers,
	undo,
} from '../../state';
import { Tool } from '../../tools';
import { pickEntityAt } from '../eraser-tool.helpers';
import {
	type DrawEvent,
	END_STATE,
	type MouseClickEvent,
	type PointInputEvent,
	type StateEvent,
	type ToolContext,
} from '../tool.types';
import { offsetEntity } from './modify.helpers';

interface OffsetContext extends ToolContext {
	/** 간격띄울 객체 */
	sourceId: string | null;
	/** 처음 고른 객체 — 원본 지우기는 이것만 */
	pickedId: string | null;
	multiple: boolean;
	/** 이 명령에서 만든 수(U) */
	made: number;
}

type Ctx = { context: OffsetContext; event: StateEvent };

const option = (key: string, kw: string, label: string): OptionSpec => ({
	key,
	kw,
	en: key,
	label,
});
const THROUGH = option('THROUGH', 'T', '통과점');

/** 기억한 거리 · null = 통과점 */
const offsetDistance = (): number | null => {
	const distance = recall('OFFSETDIST');
	return typeof distance === 'number' ? distance : null;
};

const DISTANCE_PROMPT = (): PromptSpec => {
	const distance = offsetDistance();
	return {
		text: '간격띄우기 거리 지정',
		options: [THROUGH, option('ERASE', 'E', '지우기')],
		absent: [option('LAYER', 'L', '도면층')],
		default:
			distance === null
				? { kind: 'option', key: 'THROUGH' }
				: { kind: 'value', remember: 'OFFSETDIST', initial: distance },
		number: { positive: true },
	};
};
const ERASE_PROMPT = (): PromptSpec => ({
	text: '간격띄우기 후 원본 객체를 지우시겠습니까?',
	options: [OPT.YES, OPT.NO],
	default: { kind: 'option', key: recall('OFFSETERASE') ? 'YES' : 'NO' },
});
const OBJECT_PROMPT: PromptSpec = {
	text: '간격띄우기할 객체 선택',
	options: [OPT.EXIT, OPT.UNDO],
	default: { kind: 'enter', label: '종료' },
};
const SIDE_PROMPT = (context: Partial<OffsetContext>): PromptSpec => ({
	text: offsetDistance() === null ? '통과점 지정' : '간격띄우기할 면의 점 지정',
	options: context.multiple ? [OPT.EXIT, OPT.UNDO] : [OPT.EXIT, OPT.MULTIPLE, OPT.UNDO],
	default: { kind: 'enter', label: context.multiple ? '다음 객체' : '종료' },
});

/** 통과점까지 거리 — 선은 무한 직선까지(오토캐드) · 그 밖은 모양까지 */
function throughDistance(entity: Entity, point: Point): number {
	const shape = entity.getShape();
	if (shape instanceof Segment) {
		const { start, end } = shape;
		const length = start.distanceTo(end)[0] || 1;
		return (
			Math.abs((end.x - start.x) * (point.y - start.y) - (end.y - start.y) * (point.x - start.x)) /
			length
		);
	}
	return findClosestEntity(point, [entity]).distance;
}

function offsetThrough(source: Entity, point: Point): Entity | null {
	return offsetEntity(source, offsetDistance() ?? throughDistance(source, point), point);
}

const sourceOf = (context: OffsetContext) =>
	getEntities().find((entity) => entity.id === context.sourceId);

/** 면의 점 하나 → 새 객체 · 다중이면 그것이 다음 원본 */
const placeOffset = assign(({ context, event }: Ctx): Partial<OffsetContext> => {
	const source = sourceOf(context);
	if (!source) return { sourceId: null };
	const point = getPointFromEvent(null, event as PointInputEvent);
	const result = offsetThrough(source, point);
	setGhostHelperEntities([]);
	if (!result) {
		toast.warn('이 객체는 지정한 거리로 간격을 띄울 수 없습니다.');
		return {};
	}
	if (recall('OFFSETERASE') && source.id === context.pickedId) deleteEntities([source], false);
	addEntities([result], true);
	return { made: context.made + 1, sourceId: context.multiple ? result.id : null };
});

const undoLast = assign(({ context }: Ctx): Partial<OffsetContext> => {
	setGhostHelperEntities([]);
	if (context.made === 0) return {};
	undo();
	return { made: context.made - 1, sourceId: null, multiple: false };
});

const end = { target: END_STATE };
const toObject = { actions: assign({ sourceId: null, multiple: false }), target: 'OBJECT' };

// biome-ignore lint/suspicious/noExplicitAny: 상태마다 사건 꼴이 달라 느슨하게(순서 엔진과 같음)
const states: Record<string, any> = {
	INIT: {
		always: {
			actions: () => {
				setShouldDrawHelpers(false);
				setGhostHelperEntities([]);
				setAngleGuideOriginPoint(null);
			},
			target: 'DISTANCE',
		},
	},
	DISTANCE: {
		meta: { kind: 'number', prompt: DISTANCE_PROMPT },
		on: {
			NUMBER_INPUT: {
				actions: ({ event }: Ctx) => remember('OFFSETDIST', (event as { value: number }).value),
				target: 'OBJECT',
			},
			'OPTION.THROUGH': { actions: () => remember('OFFSETDIST', 'THROUGH'), target: 'OBJECT' },
			'OPTION.ERASE': { target: 'ERASE' },
			ESC: end,
		},
	},
	ERASE: {
		meta: { kind: 'keyword', prompt: ERASE_PROMPT },
		on: {
			'OPTION.YES': { actions: () => remember('OFFSETERASE', true), target: 'DISTANCE' },
			'OPTION.NO': { actions: () => remember('OFFSETERASE', false), target: 'DISTANCE' },
			ESC: end,
		},
	},
	OBJECT: {
		meta: { kind: 'entity', prompt: OBJECT_PROMPT },
		entry: () => setShouldDrawHelpers(false),
		on: {
			MOUSE_CLICK: {
				guard: ({ event }: Ctx) => !!pickEntityAt((event as MouseClickEvent).worldMouseLocation),
				actions: assign(({ event }: Ctx) => {
					const id = pickEntityAt((event as MouseClickEvent).worldMouseLocation)?.id ?? null;
					return { sourceId: id, pickedId: id };
				}),
				target: 'SIDE',
			},
			'OPTION.EXIT': end,
			'OPTION.UNDO': { actions: undoLast },
			ENTER: end,
			ESC: end,
		},
	},
	SIDE: {
		meta: { kind: 'point', prompt: SIDE_PROMPT },
		entry: () => setShouldDrawHelpers(true),
		on: {
			DRAW: {
				actions: ({ context, event }: Ctx) => {
					const source = sourceOf(context);
					const preview =
						source && offsetThrough(source, getPointFromEvent(null, event as DrawEvent));
					setGhostHelperEntities(preview ? [preview] : []);
				},
			},
			MOUSE_CLICK: { actions: placeOffset, target: 'PLACED' },
			ABSOLUTE_POINT_INPUT: { actions: placeOffset, target: 'PLACED' },
			'OPTION.EXIT': end,
			'OPTION.MULTIPLE': { actions: assign({ multiple: true }) },
			'OPTION.UNDO': { actions: undoLast, target: 'OBJECT' },
			ENTER: [{ guard: ({ context }: Ctx) => context.multiple, ...toObject }, end],
			ESC: end,
		},
	},
	/** 다중이면 같은 물음 · 아니면 객체로 */
	PLACED: {
		always: [{ guard: ({ context }: Ctx) => !!context.sourceId, target: 'SIDE' }, toObject],
	},
	[END_STATE]: { type: 'final' },
};

export const offsetToolStateMachine = createMachine({
	types: {} as { context: OffsetContext; events: StateEvent },
	context: { sourceId: null, pickedId: null, multiple: false, made: 0, type: Tool.OFFSET },
	initial: 'INIT',
	states,
});