import { describe, expect, it } from "vitest";
import {
	calculateEncounterDifficulty,
	crToXp,
} from "../encounter-difficulty.js";

describe("crToXp", () => {
	it("returns 0 for CR 0", () => {
		expect(crToXp("0")).toBe(0);
	});

	it("returns 25 for CR 1/8", () => {
		expect(crToXp("1/8")).toBe(25);
	});

	it("returns 50 for CR 1/4", () => {
		expect(crToXp("1/4")).toBe(50);
	});

	it("returns 100 for CR 1/2", () => {
		expect(crToXp("1/2")).toBe(100);
	});

	it("returns 200 for CR 1", () => {
		expect(crToXp("1")).toBe(200);
	});

	it("returns 155000 for CR 30", () => {
		expect(crToXp("30")).toBe(155000);
	});

	it("returns 0 for unknown CR", () => {
		expect(crToXp("99")).toBe(0);
		expect(crToXp("")).toBe(0);
		expect(crToXp("abc")).toBe(0);
	});
});

describe("calculateEncounterDifficulty", () => {
	it("returns trivial when monster XP is below Low threshold", () => {
		// 4x level 1: Low = 200, Moderate = 300, High = 400
		// 1x CR 0 = 0 XP → trivial
		const result = calculateEncounterDifficulty([1, 1, 1, 1], ["0"]);
		expect(result.tier).toBe("trivial");
		expect(result.totalMonsterXp).toBe(0);
		expect(result.partyBudget).toEqual({
			low: 200,
			moderate: 300,
			high: 400,
		});
	});

	it("returns low for 4x level 1 vs Bugbear (CR 1)", () => {
		// DMG example: 4x level 1 PCs vs 1 Bugbear (CR 1, 200 XP)
		// Low = 200, Moderate = 300 → 200 >= 200 but < 300 → Low
		const result = calculateEncounterDifficulty([1, 1, 1, 1], ["1"]);
		expect(result.tier).toBe("low");
		expect(result.totalMonsterXp).toBe(200);
	});

	it("returns moderate for 5x level 3 vs 1125 XP", () => {
		// 5x level 3: Low = 750, Moderate = 1125, High = 2000
		// 1125 XP >= 1125 Moderate but < 2000 High → Moderate
		// Using CR 3 (700) + CR 2 (450) = 1150 XP ≈ 1125 threshold
		// Let's use exact: 5 * 225 = 1125 moderate budget
		// Need monsters that sum exactly to 1125: CR 3 (700) + CR 2 (450) = 1150
		const result = calculateEncounterDifficulty([3, 3, 3, 3, 3], ["3", "2"]);
		expect(result.tier).toBe("moderate");
		expect(result.totalMonsterXp).toBe(1150);
		expect(result.partyBudget.moderate).toBe(1125);
	});

	it("returns high when XP meets High threshold", () => {
		// 4x level 1: High = 400
		// 2x CR 1 = 400 XP → High
		const result = calculateEncounterDifficulty([1, 1, 1, 1], ["1", "1"]);
		expect(result.tier).toBe("high");
		expect(result.totalMonsterXp).toBe(400);
	});

	it("caps at high when XP far exceeds threshold", () => {
		// 4x level 1: High = 400
		// CR 30 = 155000 XP → still High (no tier above)
		const result = calculateEncounterDifficulty([1, 1, 1, 1], ["30"]);
		expect(result.tier).toBe("high");
		expect(result.totalMonsterXp).toBe(155000);
	});

	it("handles mixed party levels", () => {
		// 3x level 3 + 1x level 2
		// level 3: low=150, mod=225, high=400 (x3 = 450, 675, 1200)
		// level 2: low=100, mod=150, high=200 (x1 = 100, 150, 200)
		// Total: low=550, mod=825, high=1400
		const result = calculateEncounterDifficulty([3, 3, 3, 2], ["3"]);
		expect(result.partyBudget).toEqual({
			low: 550,
			moderate: 825,
			high: 1400,
		});
		expect(result.totalMonsterXp).toBe(700);
		expect(result.tier).toBe("low");
	});

	it("returns trivial with empty monster array", () => {
		const result = calculateEncounterDifficulty([5, 5], []);
		expect(result.tier).toBe("trivial");
		expect(result.totalMonsterXp).toBe(0);
	});

	it("returns high with empty party array (zero budget thresholds)", () => {
		// Domain function treats empty party as zero budgets — any XP exceeds all thresholds.
		// The useDifficulty hook guards this path by returning null when no leveled PCs exist.
		const result = calculateEncounterDifficulty([], ["1"]);
		expect(result.tier).toBe("high");
		expect(result.totalMonsterXp).toBe(200);
		expect(result.partyBudget).toEqual({ low: 0, moderate: 0, high: 0 });
	});

	it("handles fractional CRs", () => {
		const result = calculateEncounterDifficulty(
			[1, 1, 1, 1],
			["1/8", "1/4", "1/2"],
		);
		expect(result.totalMonsterXp).toBe(175); // 25 + 50 + 100
		expect(result.tier).toBe("trivial"); // 175 < 200 Low
	});

	it("ignores unknown CRs (0 XP)", () => {
		const result = calculateEncounterDifficulty([1, 1, 1, 1], ["unknown"]);
		expect(result.totalMonsterXp).toBe(0);
		expect(result.tier).toBe("trivial");
	});
});