import type { ComposerImage } from '#/lib/media/composer-image';

import * as Toast from '#/components/Toast';

import { m } from '#/paraglide/messages';

import { MAX_GALLERY_IMAGES, type PostAction } from './state/composer';

/** Clamps a batch of incoming images against the remaining gallery slots. Never mutates its inputs. */
export function applyGalleryCap(
	currentCount: number,
	incoming: ComposerImage[],
):
	| { status: 'full' }
	| { status: 'partial'; accepted: ComposerImage[]; dropped: number }
	| { status: 'ok'; accepted: ComposerImage[] } {
	const remaining = MAX_GALLERY_IMAGES - currentCount;
	if (remaining <= 0) {
		return { status: 'full' };
	}
	if (incoming.length > remaining) {
		return {
			status: 'partial',
			accepted: incoming.slice(0, remaining),
			dropped: incoming.length - remaining,
		};
	}
	return { status: 'ok', accepted: incoming };
}

/**
 * returns an adder that applies the gallery cap, toasting when the batch is fully or partially rejected.
 *
 * @param currentCount the number of images already in the gallery
 * @param dispatchPostAction dispatches accepted images to the composer
 * @returns an image-adder callback constrained by the remaining gallery capacity
 */
export function createAddImagesWithCap(
	currentCount: number,
	dispatchPostAction: (action: PostAction) => void,
) {
	return (next: ComposerImage[]) => {
		const result = applyGalleryCap(currentCount, next);
		if (result.status === 'full') {
			Toast.show(m['view.composer.gallery.error.maxAdd']({ max: MAX_GALLERY_IMAGES }), { type: 'warning' });
			return;
		}
		if (result.status === 'partial') {
			Toast.show(
				m['view.composer.gallery.error.limit']({
					accepted: result.accepted.length,
					count: next.length,
					total: next.length,
					max: MAX_GALLERY_IMAGES,
				}),
				{ type: 'warning' },
			);
		}
		dispatchPostAction({
			type: 'embedAddImages',
			images: result.accepted,
		});
	};
}