/**
 * TRIM · EXTEND 빠른 모드(337 설계 1-2) — 누를 때마다 자름(연장) · Shift+누름 = 반대 일 · 되풀이 ·
 * 빈 Enter · Esc = 끝 · 집기 반경 밖 누름은 아무 일 없음(N9) · U = 이 명령 안 마지막 하나 ·
 * TRIM 지우기(R) = 고르기 → Enter 로 지우고 돌아옴.
 */
import type { Point, Polygon } from '@flatten-js/core';
import { assign, createMachine, sendTo } from 'xstate';
import {
	OPT,
	type OptionSpec,
	type PromptSpec,
	SELECT_OBJECTS,
	rememberSelection,
} from '../commands/prompt';
import type { ArcEntity } from '../entities/ArcEntity';
import type { CircleEntity } from '../entities/CircleEntity';
import { EntityName } from '../entities/Entity';
import { LineEntity } from '../entities/LineEntity';
import type { RectangleEntity } from '../entities/RectangleEntity';
import { findClosestEntity } from '../helpers/find-closest-entity';
import { pickRadius } from '../helpers/pick-radius';
import { polygonToSegments } from '../helpers/polygon-to-segments';
import {
	addEntities,
	deleteEntities,
	getEntities,
	getPickableEntities,
	getSelectedEntities,
	setEntities,
	setGhostHelperEntities,
	setSelectedEntityIds,
	setShouldDrawHelpers,
	undo,
} from '../state';
import { Tool } from '../tools';
import {
	eraseArcSegment,
	eraseCircleSegment,
	eraseLineSegment,
	extendLineEnd,
	getAllIntersectionPoints,
	pickEntityAt,
} from './eraser-tool.helpers';
import { copyStyle } from './modify/modify.helpers';
import { selectToolStateMachine } from './select-tool';
import { END_STATE, type MouseClickEvent, type StateEvent, type ToolContext } from './tool.types';

export interface EraserContext extends ToolContext {
	/** 이 명령에서 바꾼 횟수(U) */
	made: number;
}

export enum EraserState {
	INIT = 'INIT',
	WAITING_FOR_FIRST_CLICK = 'WAITING_FOR_FIRST_CLICK',
	ERASE_PICK = 'ERASE_PICK',
}

const absent = (key: string, kw: string, label: string): OptionSpec => ({
	key,
	kw,
	en: key,
	label,
});
const HIDDEN_UNDO: OptionSpec = { ...OPT.UNDO, hidden: true };
const CROSSING = absent('CROSSING', 'C', '걸치기');
const MODE = absent('MODE', 'O', '모드');
const PROJECT = absent('PROJECT', 'P', '투영');

const TRIM_PROMPT: PromptSpec = {
	text: '자를 객체 선택 또는 Shift 키를 누른 채 선택하여 연장',
	options: [{ key: 'ERASE', kw: 'R', en: 'ERASE', label: '지우기' }, HIDDEN_UNDO],
	absent: [absent('CUTTINGEDGES', 'T', '절단 모서리'), CROSSING, MODE, PROJECT],
};
const EXTEND_PROMPT: PromptSpec = {
	text: '연장할 객체 선택 또는 Shift 키를 누른 채 선택하여 자르기',
	options: [HIDDEN_UNDO],
	absent: [absent('BOUNDARYEDGES', 'B', '경계 모서리'), CROSSING, MODE, PROJECT],
};

/** TRIM 한 번 — 누른 자리 반경 안 객체만(없으면 false) · 사각형 변은 원래 층 · 꼴 */
export function handleMouseClick(
	worldMouseLocation: Point,
	radius = Number.POSITIVE_INFINITY
): boolean {
	const closestEntity = findClosestEntity(worldMouseLocation, getPickableEntities());
	if (!closestEntity.entity || closestEntity.distance > radius) {
		return false;
	}

	const clickedPointOnShape = closestEntity.segment.start;

	// Find entities that intersect with the closest entity
	const intersections = getAllIntersectionPoints(closestEntity.entity, getPickableEntities());

	const entityType = closestEntity.entity.getType();
	switch (entityType) {
		case EntityName.Line: {
			const line = closestEntity.entity as LineEntity;
			eraseLineSegment(line, clickedPointOnShape, intersections);
			break;
		}

		case EntityName.Circle: {
			const circle = closestEntity.entity as CircleEntity;
			eraseCircleSegment(circle, clickedPointOnShape, intersections);
			break;
		}

		case EntityName.Arc: {
			const arc = closestEntity.entity as ArcEntity;
			eraseArcSegment(arc, clickedPointOnShape, intersections);
			break;
		}

		case EntityName.Rectangle: {
			const rectangle = closestEntity.entity as RectangleEntity;
			const segments = polygonToSegments(rectangle.getShape() as Polygon);
			const segmentEntities = segments.map((segment) =>
				copyStyle(rectangle, new LineEntity(rectangle.layerId, segment))
			);

			// Find the closest segment to the clicked point
			const closestSegmentInfo = findClosestEntity(worldMouseLocation, segmentEntities);

			// Remove the rectangle
			deleteEntities([rectangle], false);

			// Add 4 lines instead of the rectangle
			addEntities(segmentEntities, false);

			// Remove (a segment) of the 4th line closest to the cursor
			const lineIntersections = getAllIntersectionPoints(
				closestSegmentInfo.entity,
				getPickableEntities()
			);
			eraseLineSegment(
				closestSegmentInfo.entity as LineEntity,
				clickedPointOnShape,
				lineIntersections
			);
			break;
		}

		default:
			return false;
	}

	setEntities(getEntities(), true); // Force a new undo state entry
	return true;
}

/** EXTEND 한 번 — 누른 쪽 끝을 가장 가까운 경계까지 · 못 늘리면 false */
export function extendAt(worldMouseLocation: Point): boolean {
	const target = pickEntityAt(worldMouseLocation);
	if (!target) return false;
	const extended = extendLineEnd(target, worldMouseLocation, getPickableEntities());
	if (!extended) return false;
	deleteEntities([target], false);
	addEntities([extended], true);
	return true;
}

const trimAt = (location: Point) => handleMouseClick(location, pickRadius());

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

/** 빠른 자르기 · 연장 머신 — `act(점, shift)` 가 바꿨으면 true */
function createQuickEditTool(
	tool: Tool,
	prompt: PromptSpec,
	act: (location: Point, shift: boolean) => boolean
) {
	const undoLast = assign(({ context }: Ctx) => {
		if (context.made === 0) return {};
		undo();
		return { made: context.made - 1 };
	});
	const end = { target: END_STATE };
	const forward = { actions: sendTo('trimErase', ({ event }: Ctx) => event) };
	const takesErase = prompt.options?.some((option) => option.key === 'ERASE');

	return createMachine(
		{
			types: {} as { context: EraserContext; events: StateEvent },
			context: { made: 0, type: tool },
			initial: EraserState.INIT,
			// biome-ignore lint/suspicious/noExplicitAny: 상태마다 사건 꼴이 달라 느슨하게(순서 엔진과 같음)
			states: <Record<string, any>>{
				[EraserState.INIT]: {
					always: {
						actions: () => {
							setShouldDrawHelpers(false);
							setGhostHelperEntities([]);
						},
						target: EraserState.WAITING_FOR_FIRST_CLICK,
					},
				},
				[EraserState.WAITING_FOR_FIRST_CLICK]: {
					meta: { kind: 'entity', prompt },
					on: {
						MOUSE_CLICK: {
							actions: assign(({ context, event }: Ctx) => {
								const click = event as MouseClickEvent;
								return act(click.worldMouseLocation, !!click.holdingShift)
									? { made: context.made + 1 }
									: {};
							}),
						},
						...(takesErase ? { 'OPTION.ERASE': { target: EraserState.ERASE_PICK } } : {}),
						'OPTION.UNDO': { actions: undoLast },
						ENTER: end,
						ESC: end,
					},
				},
				...(takesErase
					? {
							[EraserState.ERASE_PICK]: {
								meta: {
									kind: 'selection',
									prompt: { text: '지울 객체 선택', options: SELECT_OBJECTS.options },
								},
								entry: () => setShouldDrawHelpers(false),
								invoke: {
									id: 'trimErase',
									src: selectToolStateMachine,
									onDone: {
										actions: assign(({ context }: Ctx) => {
											const picked = getSelectedEntities();
											if (!picked.length) return {};
											rememberSelection(picked.map((entity) => entity.id));
											setSelectedEntityIds([]);
											deleteEntities(picked, true);
											return { made: context.made + 1 };
										}),
										target: EraserState.WAITING_FOR_FIRST_CLICK,
									},
								},
								on: {
									MOUSE_CLICK: forward,
									ENTER: forward,
									DRAW: forward,
									'OPTION.*': forward,
									ESC: { actions: () => setSelectedEntityIds([]), target: END_STATE },
								},
							},
						}
					: {}),
				[END_STATE]: { type: 'final' },
			},
		},
		{
			// 고르기 자식(선택 도구)의 액션 구현을 함께 넘긴다
			// biome-ignore lint/suspicious/noExplicitAny: 자식 머신의 컨텍스트 타입이 달라 그대로 넘긴다
			actions: { ...(selectToolStateMachine.implementations.actions as any) },
		}
	);
}

export const eraserToolStateMachine = createQuickEditTool(
	Tool.ERASER,
	TRIM_PROMPT,
	(location, shift) => (shift ? extendAt(location) : trimAt(location))
);

export const extendToolStateMachine = createQuickEditTool(
	Tool.EXTEND,
	EXTEND_PROMPT,
	(location, shift) => (shift ? trimAt(location) : extendAt(location))
);