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

import type { Instance as PopperInstance } from '@popperjs/core';
import { createPopper } from '@popperjs/core';
import type { App, ISuggestOwner } from 'obsidian';
import { Scope } from 'obsidian';
import { wrapAround } from 'src/utils/Utils';

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

	constructor(owner: ISuggestOwner<T>, containerEl: HTMLElement, scope: Scope) {
		this.owner = owner;
		this.containerEl = containerEl;
		this.values = [];
		this.suggestions = [];
		this.selectedItem = 0;

		containerEl.on('click', '.suggestion-item', (e, el) => this.onSuggestionClick(e, el));
		containerEl.on('mousemove', '.suggestion-item', (e, el) => this.onSuggestionMouseover(e, el));

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

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

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

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

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

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

	setSuggestions(values: T[]): void {
		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): void {
		const currentValue = this.values[this.selectedItem];
		if (currentValue) {
			this.owner.selectSuggestion(currentValue, event);
		}
	}

	setSelectedItem(selectedIndex: number, scrollIntoView: boolean): void {
		const normalizedIndex = this.suggestions.length > 0 ? wrapAround(selectedIndex, this.suggestions.length) : 0;
		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);
		}
	}
}

export abstract class TextInputSuggest<T> implements ISuggestOwner<T> {
	protected app: App;
	protected inputEl: HTMLInputElement;

	private popper?: PopperInstance;
	private scope: Scope;
	private suggestEl: HTMLElement;
	private suggest: Suggest<T>;

	constructor(app: App, inputEl: HTMLInputElement) {
		this.app = app;
		this.inputEl = inputEl;
		this.scope = new Scope();

		this.suggestEl = createDiv('suggestion-container');
		const suggestion = this.suggestEl.createDiv('suggestion');
		this.suggest = new Suggest(this, suggestion, this.scope);

		this.scope.register([], 'Escape', this.close.bind(this));

		this.inputEl.addEventListener('input', this.onInputChanged.bind(this));
		this.inputEl.addEventListener('focus', this.onInputChanged.bind(this));
		this.inputEl.addEventListener('blur', this.close.bind(this));
		this.suggestEl.on('mousedown', '.suggestion-container', (event: MouseEvent) => {
			event.preventDefault();
		});
	}

	onInputChanged(): void {
		const inputStr = this.inputEl.value;
		const suggestions = this.getSuggestions(inputStr);

		if (suggestions.length > 0) {
			this.suggest.setSuggestions(suggestions);
			// eslint-disable-next-line @typescript-eslint/no-explicit-any
			this.open((this.app as any).dom.appContainerEl, this.inputEl);
		}
	}

	open(container: HTMLElement, inputEl: HTMLElement): void {
		// eslint-disable-next-line @typescript-eslint/no-explicit-any
		(this.app as any).keymap.pushScope(this.scope);

		container.appendChild(this.suggestEl);
		this.popper = createPopper(inputEl, this.suggestEl, {
			placement: 'bottom-start',
			modifiers: [
				{
					name: 'sameWidth',
					enabled: true,
					fn: ({ state, instance }): void => {
						// Note: positioning needs to be calculated twice -
						// first pass - positioning it according to the width of the popper
						// second pass - position it with the width bound to the reference element
						// we need to early exit to avoid an infinite loop
						const targetWidth = `${state.rects.reference.width}px`;
						if (state.styles.popper.width === targetWidth) {
							return;
						}
						state.styles.popper.width = targetWidth;
						instance.update();
					},
					phase: 'beforeWrite',
					requires: ['computeStyles'],
				},
			],
		});
	}

	close(): void {
		// eslint-disable-next-line @typescript-eslint/no-explicit-any
		(this.app as any).keymap.popScope(this.scope);

		this.suggest.setSuggestions([]);
		this.popper?.destroy();
		this.suggestEl.detach();
	}

	abstract getSuggestions(inputStr: string): T[];

	abstract renderSuggestion(item: T, el: HTMLElement): void;

	abstract selectSuggestion(item: T): void;
}