scroll/src/common/search.ts

import Document from './document.ts';

import { KeyCommand } from './ansi.ts';
import Option, { None } from './option.ts';
import { Position } from './types.ts';

enum SearchDirection {
	Forward = 1,
	Backward = -1,
}

export class Search {
	private lastMatch: number = -1;
	private current: number = -1;
	private direction: SearchDirection = SearchDirection.Forward;
	public parent: Option<Document> = None;

	private parseInput(key: string) {
		switch (key) {
			case KeyCommand.ArrowRight:
			case KeyCommand.ArrowDown:
				this.direction = SearchDirection.Forward;
				break;

			case KeyCommand.ArrowLeft:
			case KeyCommand.ArrowUp:
				this.direction = SearchDirection.Backward;
				break;

			default:
				this.lastMatch = -1;
				this.direction = SearchDirection.Forward;
		}

		if (this.lastMatch === -1) {
			this.direction = SearchDirection.Forward;
		}

		this.current = this.lastMatch;
	}

	private getNextRow(rowCount: number): number {
		this.current += this.direction;
		if (this.current === -1) {
			this.current = rowCount - 1;
		} else if (this.current === rowCount) {
			this.current = 0;
		}

		return this.current;
	}

	public search(q: string, key: string): Option<Position> {
		if (this.parent.isNone()) {
			return None;
		}

		const parent = this.parent.unwrap();

		this.parseInput(key);

		let i = 0;
		for (; i < parent.numRows; i++) {
			const current = this.getNextRow(parent.numRows);
			const row = parent.row(current);

			if (row === null) {
				continue;
			}

			const possible = row.find(q);
			if (possible.isSome()) {
				this.lastMatch = current;
				return possible.map((p: number) => Position.at(p, current));
			}
		}

		return None;
	}
}