const test = require("node:test");
const assert = require("node:assert/strict");

function monthToYear(month) {
	const match = String(month || "").match(/(20\d{2})/);
	return match ? Number(match[1]) : new Date().getFullYear();
}

function buildHistoryEntry(surcharges, baseSS) {
	const month =
		surcharges["316"]?.month ||
		surcharges["304"]?.month ||
		surcharges["444"]?.month ||
		"";

	return {
		m: month,
		y: monthToYear(month),
		ss: Number.isFinite(Number(baseSS)) ? Number(baseSS) : null,
		lz304: Number(surcharges["304"]?.value) || 0,
		lz316: Number(surcharges["316"]?.value) || 0,
		lz444: Number(surcharges["444"]?.value) || 0,
	};
}

function getSaveMonth(surcharges, editMode, editMonth) {
	if (editMode) return editMonth;

	return (
		surcharges["316"]?.month ||
		surcharges["304"]?.month ||
		surcharges["444"]?.month ||
		""
	);
}

function cloneSurcharges(surcharges) {
	return {
		304: {
			...(surcharges["304"] || { month: "", value: 0 }),
		},
		316: {
			...(surcharges["316"] || { month: "", value: 0 }),
		},
		444: {
			...(surcharges["444"] || { month: "", value: 0 }),
		},
	};
}

function shouldUseEditedCurrentValues(editMode, editMonth, editSnapshot) {
	if (!editMode || !editSnapshot) return true;

	return getSaveMonth(editSnapshot.surcharges, false, "") === editMonth;
}

function buildSaveEntry(surcharges, baseSS, saveMonth) {
	const entry = buildHistoryEntry(surcharges, baseSS);

	return {
		...entry,
		m: saveMonth,
		y: monthToYear(saveMonth),
	};
}

function upsertHistory(history, entry) {
	if (!entry.m) return history;

	const existingIndex = history.findIndex(
		(historyEntry) => historyEntry.m === entry.m,
	);
	if (existingIndex >= 0) {
		const nextHistory = [...history];
		nextHistory[existingIndex] = { ...nextHistory[existingIndex], ...entry };
		return nextHistory;
	}

	return [...history, entry];
}

test("monthToYear extracts year", () => {
	assert.equal(monthToYear("Apr. 2026"), 2026);
	assert.equal(monthToYear("Jan 2025"), 2025);
});

test("buildSaveEntry persists base price and surcharge values", () => {
	const surcharges = {
		304: { month: "Apr. 2026", value: 2663 },
		316: { month: "Apr. 2026", value: 4591 },
		444: { month: "Apr. 2026", value: 2817 },
	};

	const entry = buildSaveEntry(surcharges, 813, "Apr. 2026");

	assert.equal(entry.m, "Apr. 2026");
	assert.equal(entry.y, 2026);
	assert.equal(entry.ss, 813);
	assert.equal(entry.lz304, 2663);
	assert.equal(entry.lz316, 4591);
	assert.equal(entry.lz444, 2817);
});

test("buildSaveEntry uses explicit save month", () => {
	const surcharges = {
		304: { month: "Apr. 2026", value: 2663 },
		316: { month: "Apr. 2026", value: 4591 },
		444: { month: "Apr. 2026", value: 2817 },
	};

	const entry = buildSaveEntry(surcharges, 755, "Feb 2026");

	assert.equal(entry.m, "Feb 2026");
	assert.equal(entry.y, 2026);
	assert.equal(entry.ss, 755);
	assert.equal(entry.lz316, 4591);
});

test("shouldUseEditedCurrentValues returns false for older month edit", () => {
	const editSnapshot = {
		baseSS: 813,
		surcharges: cloneSurcharges({
			304: { month: "Apr. 2026", value: 2663 },
			316: { month: "Apr. 2026", value: 4591 },
			444: { month: "Apr. 2026", value: 2817 },
		}),
	};

	assert.equal(
		shouldUseEditedCurrentValues(true, "Feb 2026", editSnapshot),
		false,
	);
});

test("shouldUseEditedCurrentValues returns true for current month edit", () => {
	const editSnapshot = {
		baseSS: 813,
		surcharges: cloneSurcharges({
			304: { month: "Apr. 2026", value: 2663 },
			316: { month: "Apr. 2026", value: 4591 },
			444: { month: "Apr. 2026", value: 2817 },
		}),
	};

	assert.equal(
		shouldUseEditedCurrentValues(true, "Apr. 2026", editSnapshot),
		true,
	);
});

test("shouldUseEditedCurrentValues returns true outside edit mode", () => {
	const editSnapshot = {
		baseSS: 813,
		surcharges: cloneSurcharges({
			304: { month: "Apr. 2026", value: 2663 },
			316: { month: "Apr. 2026", value: 4591 },
			444: { month: "Apr. 2026", value: 2817 },
		}),
	};

	assert.equal(
		shouldUseEditedCurrentValues(false, "Feb 2026", editSnapshot),
		true,
	);
});

test("upsertHistory appends entry for new month", () => {
	const history = [
		{ m: "Feb 2026", y: 2026, ss: 755, lz304: 2541, lz316: 4179, lz444: 2522 },
		{ m: "Mrz 2026", y: 2026, ss: 792, lz304: 2571, lz316: 4367, lz444: 2637 },
	];
	const entry = {
		m: "Apr 2026",
		y: 2026,
		ss: 813,
		lz304: 2663,
		lz316: 4591,
		lz444: 2817,
	};

	const result = upsertHistory(history, entry);

	assert.equal(result.length, 3);
	assert.equal(result[2].m, "Apr 2026");
});

test("upsertHistory updates existing month without duplicate", () => {
	const history = [
		{ m: "Feb 2026", y: 2026, ss: 755, lz304: 2541, lz316: 4179, lz444: 2522 },
		{ m: "Mrz 2026", y: 2026, ss: 792, lz304: 2571, lz316: 4367, lz444: 2637 },
	];
	const entry = {
		m: "Mrz 2026",
		ss: 800,
		lz304: 2600,
		lz316: 4400,
		lz444: 2650,
	};

	const result = upsertHistory(history, entry);

	assert.equal(result.length, 2);
	assert.equal(result[1].m, "Mrz 2026");
	assert.equal(result[1].y, 2026);
	assert.equal(result[1].ss, 800);
	assert.equal(result[1].lz444, 2650);
});

test("upsertHistory keeps history unchanged for missing month", () => {
	const history = [
		{ m: "Feb 2026", y: 2026, ss: 755, lz304: 2541, lz316: 4179, lz444: 2522 },
	];

	const result = upsertHistory(history, { m: "", ss: 700 });

	assert.deepEqual(result, history);
});