import {
	type Middleware,
	type Placement,
	arrow,
	autoUpdate,
	flip,
	hide,
	limitShift,
	offset,
	shift,
	size
} from '@floating-ui/dom';
import { attachRef, type RefAttachment } from '$libs/reactive';
import { cssToStyleObj, styleToString } from '$soma/css';
import type { ActiveDom } from '$adom';
import { state, readableActive, type Active, type ActiveProps } from '$libs/reactive';
import { isNotNull } from '$soma/types';
import { useId } from '$soma/id';
import { context, type SomaContext } from '$soma/provider';
import type { Arrayable, Direction, StyleProperties } from '$soma/types';
import type { WithRefOpts } from '$soma/provider';
import { ElementSize, watch } from 'runed';

import { useFloating } from './use-floating.svelte';
import type { Measurable, UseFloatingReturn } from './types';
import { OPPOSITE_SIDE, type Align, type Boundary, type Side } from './placement';

// ── FloatingProvider ─────────────────────────────────────────────────────────

export interface FloatingProviderOpts {
	dom: ActiveDom;
}

export class FloatingProvider {
	static readonly ctx = context<FloatingProvider>('FloatingProvider');

	static create(opts: FloatingProviderOpts) {
		return FloatingProvider.ctx.set(new FloatingProvider(opts));
	}

	readonly opts: FloatingProviderOpts;
	anchorNode = state<Measurable | HTMLElement | null>(null);
	customAnchorNode = state<Measurable | HTMLElement | null | string>(null);
	triggerNode: Active<Measurable | HTMLElement | null> = state(null);

	private constructor(opts: FloatingProviderOpts) {
		this.opts = opts;
		$effect(() => {
			if (this.customAnchorNode.current) {
				if (typeof this.customAnchorNode.current === 'string') {
					const el = this.opts.dom.query(this.customAnchorNode.current);
					this.anchorNode.current = el;
				} else {
					this.anchorNode.current = this.customAnchorNode.current;
				}
			} else {
				this.anchorNode.current = this.triggerNode.current;
			}
		});
	}
}

// ── FloatingContent ──────────────────────────────────────────────────────────

export interface FloatingContentOpts extends ActiveProps<{
	id: string;
	wrapperId: string;
	side: Side;
	sideOffset: number;
	align: Align;
	alignOffset: number;
	arrowPadding: number;
	avoidCollisions: boolean;
	collisionBoundary: Arrayable<Boundary>;
	collisionPadding: number | Partial<Record<Side, number>>;
	sticky: 'partial' | 'always';
	hideWhenDetached: boolean;
	updatePositionStrategy: 'optimized' | 'always';
	strategy: 'fixed' | 'absolute';
	onPlaced: () => void;
	dir: Direction;
	style: StyleProperties | null | undefined | string;
	enabled: boolean;
	customAnchor: string | HTMLElement | null | Measurable;
}> {}

export class FloatingContent {
	static readonly ctx = context<FloatingContent>('FloatingContent');

	static create(opts: FloatingContentOpts) {
		return FloatingContent.ctx.set(new FloatingContent(opts, FloatingProvider.ctx.get()));
	}

	readonly opts: FloatingContentOpts;
	readonly provider: FloatingProvider;

	// nodes
	contentRef = state<HTMLElement | null>(null);
	wrapperRef = state<HTMLElement | null>(null);
	arrowRef = state<HTMLElement | null>(null);
	readonly contentAttachment: RefAttachment = attachRef(this.contentRef);
	readonly wrapperAttachment: RefAttachment = attachRef(this.wrapperRef);
	readonly arrowAttachment: RefAttachment = attachRef(this.arrowRef);

	// ids
	arrowId = state(useId());

	transformedStyle = $derived.by(() => {
		if (typeof this.opts.style === 'string') return cssToStyleObj(this.opts.style);
		if (!this.opts.style) return {};
	});

	updatePositionStrategy = undefined as unknown as FloatingContentOpts['updatePositionStrategy'];
	arrowSize = new ElementSize(() => this.arrowRef.current ?? undefined);
	arrowWidth = $derived(this.arrowSize?.width ?? 0);
	arrowHeight = $derived(this.arrowSize?.height ?? 0);
	desiredPlacement = $derived.by(
		() =>
			(this.opts.side?.current +
				(this.opts.align.current !== 'center' ? `-${this.opts.align.current}` : '')) as Placement
	);
	boundary = $derived.by(() =>
		Array.isArray(this.opts.collisionBoundary.current)
			? this.opts.collisionBoundary.current
			: [this.opts.collisionBoundary.current]
	);
	hasExplicitBoundaries = $derived(this.boundary.length > 0);
	detectOverflowOptions = $derived.by(() => ({
		padding: this.opts.collisionPadding.current,
		boundary: this.boundary.filter(isNotNull),
		altBoundary: this.hasExplicitBoundaries
	}));
	availableWidth = $state<number | undefined>(undefined);
	availableHeight = $state<number | undefined>(undefined);
	anchorWidth = $state<number | undefined>(undefined);
	anchorHeight = $state<number | undefined>(undefined);
	middleware: Middleware[] = $derived.by(
		() =>
			[
				offset({
					mainAxis: this.opts.sideOffset.current + this.arrowHeight,
					alignmentAxis: this.opts.alignOffset.current
				}),
				this.opts.avoidCollisions.current &&
					shift({
						mainAxis: true,
						crossAxis: false,
						limiter: this.opts.sticky.current === 'partial' ? limitShift() : undefined,
						...this.detectOverflowOptions
					}),
				this.opts.avoidCollisions.current && flip({ ...this.detectOverflowOptions }),
				size({
					...this.detectOverflowOptions,
					apply: ({ rects, availableWidth, availableHeight }) => {
						const { width: anchorWidth, height: anchorHeight } = rects.reference;
						this.availableWidth = availableWidth;
						this.availableHeight = availableHeight;
						this.anchorWidth = anchorWidth;
						this.anchorHeight = anchorHeight;
					}
				}),
				this.arrowRef.current &&
					arrow({
						element: this.arrowRef.current,
						padding: this.opts.arrowPadding.current
					}),
				transformOrigin({ arrowWidth: this.arrowWidth, arrowHeight: this.arrowHeight }),
				this.opts.hideWhenDetached.current &&
					hide({ strategy: 'referenceHidden', ...this.detectOverflowOptions })
			].filter(Boolean) as Middleware[]
	);
	floating: UseFloatingReturn;
	placedSide = $derived.by(() => getSideFromPlacement(this.floating.placement.current));
	placedAlign = $derived.by(() => getAlignFromPlacement(this.floating.placement.current));
	arrowX = $derived.by(() => this.floating.middlewareData.current.arrow?.x);
	arrowY = $derived.by(() => this.floating.middlewareData.current.arrow?.y);
	cannotCenterArrow = $derived.by(() => {
		const centerOffset = this.floating.middlewareData.current.arrow?.centerOffset;
		return centerOffset !== undefined && centerOffset !== 0;
	});
	contentZIndex = $state<string>();
	arrowBaseSide = $derived(OPPOSITE_SIDE[this.placedSide]);
	wrapperProps = $derived.by(
		() =>
			({
				id: this.opts.wrapperId.current,
				'data-soma-floating-wrapper': '',
				style: {
					...this.floating.floatingStyles.current,
					transform: this.floating.isPositioned.current
						? this.floating.floatingStyles.current.transform
						: 'translate(0, -200%)',
					minWidth: 'max-content',
					zIndex:
						this.contentZIndex && this.contentZIndex !== 'auto' ? this.contentZIndex : undefined,
					'--soma-floating-transform-origin': `${this.floating.middlewareData.current.transformOrigin?.x} ${this.floating.middlewareData.current.transformOrigin?.y}`,
					'--soma-floating-available-width': `${this.availableWidth}px`,
					'--soma-floating-available-height': `${this.availableHeight}px`,
					'--soma-floating-anchor-width': `${this.anchorWidth}px`,
					'--soma-floating-anchor-height': `${this.anchorHeight}px`,
					...(this.floating.middlewareData.current.hide?.referenceHidden && {
						visibility: 'hidden',
						'pointer-events': 'none'
					}),
					...this.transformedStyle
				},
				dir: this.opts.dir.current,
				...this.wrapperAttachment
			}) as const
	);
	props = $derived.by(
		() =>
			({
				'data-side': this.placedSide,
				'data-align': this.placedAlign,
				style: styleToString({
					...this.transformedStyle
				}),
				...this.contentAttachment
			}) as const
	);

	arrowStyle = $derived({
		position: 'absolute',
		left: this.arrowX !== undefined ? `${this.arrowX}px` : undefined,
		top: this.arrowY !== undefined ? `${this.arrowY}px` : undefined,
		[this.arrowBaseSide]: 0,
		'transform-origin': {
			top: '',
			right: '0 0',
			bottom: 'center 0',
			left: '100% 0'
		}[this.placedSide],
		transform: {
			top: 'translateY(100%)',
			right: 'translateY(50%) rotate(90deg) translateX(-50%)',
			bottom: 'rotate(180deg)',
			left: 'translateY(50%) rotate(-90deg) translateX(50%)'
		}[this.placedSide],
		visibility: this.cannotCenterArrow ? ('hidden' as const) : undefined
	});

	private constructor(opts: FloatingContentOpts, provider: FloatingProvider) {
		this.opts = opts;
		this.provider = provider;
		this.updatePositionStrategy = opts.updatePositionStrategy;

		if (opts.customAnchor) {
			this.provider.customAnchorNode.current = opts.customAnchor.current;
		}

		watch(
			() => opts.customAnchor.current,
			(customAnchor) => {
				this.provider.customAnchorNode.current = customAnchor;
			}
		);

		this.floating = useFloating({
			strategy: () => this.opts.strategy.current,
			placement: () => this.desiredPlacement,
			middleware: () => this.middleware,
			reference: this.provider.anchorNode,
			whileElementsMounted: (...args) => {
				const cleanup = autoUpdate(...args, {
					animationFrame: this.updatePositionStrategy?.current === 'always'
				});
				return cleanup;
			},
			open: () => this.opts.enabled.current,
			sideOffset: () => this.opts.sideOffset.current,
			alignOffset: () => this.opts.alignOffset.current
		});

		$effect(() => {
			if (!this.floating.isPositioned.current) return;
			this.opts.onPlaced?.current();
		});

		watch(
			() => this.contentRef.current,
			(contentNode) => {
				if (!contentNode || !this.opts.enabled.current) return;
				const rafId = this.provider.opts.dom.requestFrame(() => {
					if (this.contentRef.current !== contentNode || !this.opts.enabled.current) return;
					const zIndex = this.provider.opts.dom
						.getWindow(contentNode)
						.getComputedStyle(contentNode).zIndex;
					if (zIndex !== this.contentZIndex) {
						this.contentZIndex = zIndex;
					}
				}, contentNode);

				return () => {
					this.provider.opts.dom.cancelFrame(rafId, contentNode);
				};
			}
		);

		$effect(() => {
			this.floating.floating.current = this.wrapperRef.current;
		});
	}
}

// ── FloatingArrow ────────────────────────────────────────────────────────────

interface FloatingArrowOpts extends WithRefOpts {}

export class FloatingArrow {
	static create(opts: FloatingArrowOpts) {
		return new FloatingArrow(opts, FloatingContent.ctx.get());
	}

	readonly opts: FloatingArrowOpts;
	readonly content: FloatingContent;

	constructor(opts: FloatingArrowOpts, content: FloatingContent) {
		this.opts = opts;
		this.content = content;
	}

	readonly props = $derived.by(
		() =>
			({
				id: this.opts.id.current,
				style: this.content.arrowStyle,
				'data-side': this.content.placedSide,
				...this.content.arrowAttachment
			}) as const
	);
}

// ── FloatingAnchor ───────────────────────────────────────────────────────────

interface FloatingAnchorOpts extends ActiveProps<{
	id: string;
	virtualEl?: Measurable | null;
	ref: Measurable | HTMLElement | null;
}> {}

export class FloatingAnchor {
	static create(opts: FloatingAnchorOpts) {
		return new FloatingAnchor(opts, FloatingProvider.ctx.get());
	}

	readonly opts: FloatingAnchorOpts;
	readonly provider: FloatingProvider;

	constructor(opts: FloatingAnchorOpts, provider: FloatingProvider) {
		this.opts = opts;
		this.provider = provider;

		if (opts.virtualEl && opts.virtualEl.current) {
			provider.triggerNode = readableActive(() => opts.virtualEl!.current ?? null);
		} else {
			provider.triggerNode = opts.ref;
		}
	}
}

// ── Helpers ──────────────────────────────────────────────────────────────────

function transformOrigin(options: { arrowWidth: number; arrowHeight: number }): Middleware {
	return {
		name: 'transformOrigin',
		options,
		fn(data) {
			const { placement, rects, middlewareData } = data;

			const centerOffset = middlewareData.arrow?.centerOffset;
			const cannotCenterArrow = centerOffset !== undefined && centerOffset !== 0;
			const isArrowHidden = cannotCenterArrow;
			const arrowWidth = isArrowHidden ? 0 : options.arrowWidth;
			const arrowHeight = isArrowHidden ? 0 : options.arrowHeight;

			const [placedSide, placedAlign] = getSideAndAlignFromPlacement(placement);
			const noArrowAlign = { start: '0%', center: '50%', end: '100%' }[placedAlign];

			const arrowXCenter = (middlewareData.arrow?.x ?? 0) + arrowWidth / 2;
			const arrowYCenter = (middlewareData.arrow?.y ?? 0) + arrowHeight / 2;

			let x = '';
			let y = '';

			if (placedSide === 'bottom') {
				x = isArrowHidden ? noArrowAlign : `${arrowXCenter}px`;
				y = `${-arrowHeight}px`;
			} else if (placedSide === 'top') {
				x = isArrowHidden ? noArrowAlign : `${arrowXCenter}px`;
				y = `${rects.floating.height + arrowHeight}px`;
			} else if (placedSide === 'right') {
				x = `${-arrowHeight}px`;
				y = isArrowHidden ? noArrowAlign : `${arrowYCenter}px`;
			} else if (placedSide === 'left') {
				x = `${rects.floating.width + arrowHeight}px`;
				y = isArrowHidden ? noArrowAlign : `${arrowYCenter}px`;
			}
			return { data: { x, y } };
		}
	};
}

function getSideAndAlignFromPlacement(placement: Placement) {
	const [side, align = 'center'] = placement.split('-');
	return [side as Side, align as Align] as const;
}

export function getSideFromPlacement(placement: Placement) {
	return getSideAndAlignFromPlacement(placement)[0];
}

export function getAlignFromPlacement(placement: Placement) {
	return getSideAndAlignFromPlacement(placement)[1];
}