import { describe, it, expect } from "vitest";
import { foldConsecutiveDuplicates } from "../../extensions/compress/stages/dedup.js";

describe("foldConsecutiveDuplicates", () => {
	it("returns unchanged string with no duplicates", () => {
		const text = "line1\nline2\nline3";
		expect(foldConsecutiveDuplicates(text)).toBe(text);
	});

	it("folds 2+ identical consecutive lines (min length 5)", () => {
		const input = "hello world\nhello world\nhello world";
		expect(foldConsecutiveDuplicates(input)).toBe("[3×] hello world");
	});

	it("folds exactly 2 identical lines when length >= 5", () => {
		const input = "abcdef\nabcdef";
		expect(foldConsecutiveDuplicates(input)).toBe("[2×] abcdef");
	});

	it("does not fold short lines (< 5 chars)", () => {
		const input = "ab\nab\nab";
		expect(foldConsecutiveDuplicates(input)).toBe("ab\nab\nab");
	});

	it("does not fold empty lines (handled by whitespace stage)", () => {
		const input = "\n\n\n";
		expect(foldConsecutiveDuplicates(input)).toBe("\n\n\n");
	});

	it("folds a run then continues with different lines", () => {
		const input = "line1\nduplication\nduplication\nduplication\nline2";
		expect(foldConsecutiveDuplicates(input)).toBe("line1\n[3×] duplication\nline2");
	});

	it("handles multiple separate runs", () => {
		const input = "aaaaa\naaaaa\ndifferent\nbbbbb\nbbbbb\nbbbbb";
		expect(foldConsecutiveDuplicates(input)).toBe("[2×] aaaaa\ndifferent\n[3×] bbbbb");
	});

	it("handles separator-like lines (realistic case)", () => {
		const sep = "────────────────────────────";
		const input = [sep, sep, sep, sep, "content", sep, sep].join("\n");
		expect(foldConsecutiveDuplicates(input)).toBe(`[4×] ${sep}\ncontent\n[2×] ${sep}`);
	});

	it("handles a single line (no fold needed)", () => {
		expect(foldConsecutiveDuplicates("hello world")).toBe("hello world");
	});
});