import { App, ISuggestOwner, Scope } from "obsidian";

// Credits go to Liam's Periodic Notes Plugin: https://github.com/liamcain/obsidian-periodic-notes

const wrapAround = (value: number, size: number): number => {
	return ((value % size) + size) % size;
};

export default class Suggest<T> {
	private owner: ISuggestOwner<T>;
	private values: T[];
	private suggestions: HTMLDivElement[];
	private selectedItem: number;
	private containerEl: HTMLElement;

	constructor(owner: ISuggestOwner<T>, containerEl: HTMLElement, scope: Scope) {
		this.owner = owner;
		this.containerEl = containerEl;

		containerEl.on("click", ".suggestion-item", this.onSuggestionClick.bind(this));
		containerEl.on(
			"mousemove",
			".suggestion-item",
			this.onSuggestionMouseover.bind(this)
		);

		scope.register([], "ArrowUp", (event) => {
			if (!event.isComposing) {
				this.setSelectedItem(this.selectedItem - 1, true);
				return false;
			}
		});

		scope.register([], "ArrowDown", (event) => {
			if (!event.isComposing) {
				this.setSelectedItem(this.selectedItem + 1, true);
				return false;
			}
		});

		scope.register([], "Enter", (event) => {
			if (!event.isComposing) {
				this.useSelectedItem(event);
				return false;
			}
		});
	}

	onSuggestionClick(event: MouseEvent, el: HTMLDivElement): void {
		event.preventDefault();

		const item = this.suggestions.indexOf(el);
		this.setSelectedItem(item, false);
		this.useSelectedItem(event);
	}

	onSuggestionMouseover(_event: MouseEvent, el: HTMLDivElement): void {
		const item = this.suggestions.indexOf(el);
		this.setSelectedItem(item, false);
	}

	setSuggestions(values: T[]) {
		this.containerEl.empty();
		const suggestionEls: HTMLDivElement[] = [];

		values.forEach((value) => {
			const suggestionEl = this.containerEl.createDiv("suggestion-item");
			this.owner.renderSuggestion(value, suggestionEl);
			suggestionEls.push(suggestionEl);
		});

		this.values = values;
		this.suggestions = suggestionEls;
		this.setSelectedItem(0, false);
	}

	useSelectedItem(event: MouseEvent | KeyboardEvent) {
		const currentValue = this.values[this.selectedItem];
		if (currentValue) {
			this.owner.selectSuggestion(currentValue, event);
		}
	}

	setSelectedItem(selectedIndex: number, scrollIntoView: boolean) {
		const normalizedIndex = wrapAround(selectedIndex, this.suggestions.length);
		const prevSelectedSuggestion = this.suggestions[this.selectedItem];
		const selectedSuggestion = this.suggestions[normalizedIndex];

		prevSelectedSuggestion?.removeClass("is-selected");
		selectedSuggestion?.addClass("is-selected");

		this.selectedItem = normalizedIndex;

		if (scrollIntoView) {
			selectedSuggestion.scrollIntoView(false);
		}
	}
}