// Pure helpers for the energy tracker. Inputs come from the ned-collector tables in the
// `energy` schema (NED.nl electricity data and AGSI/GIE gas storage).

export type SourceType =
	| 'Nuclear'
	| 'WindOffshoreC'
	| 'Wind'
	| 'Solar'
	| 'BiomassPower'
	| 'WastePower'
	| 'WKK Total'
	| 'FossilGasPower'
	| 'FossilHardCoal'
	| 'OtherPower';

export type Source = {
	type: SourceType;
	label: string;
	color: string;
	renewable: boolean;
	fossil: boolean;
};

// Stacking order, bottom to top: steady baseload first, weather-driven next, fossil on top.
export const SOURCES: readonly Source[] = [
	{ type: 'Nuclear', label: 'Nuclear', color: '#a78bfa', renewable: false, fossil: false },
	{
		type: 'WindOffshoreC',
		label: 'Wind offshore',
		color: '#0284c7',
		renewable: true,
		fossil: false
	},
	{ type: 'Wind', label: 'Wind onshore', color: '#38bdf8', renewable: true, fossil: false },
	{ type: 'Solar', label: 'Solar', color: '#facc15', renewable: true, fossil: false },
	{ type: 'BiomassPower', label: 'Biomass', color: '#65a30d', renewable: true, fossil: false },
	{ type: 'WastePower', label: 'Waste', color: '#a3a3a3', renewable: false, fossil: false },
	{ type: 'WKK Total', label: 'CHP (WKK)', color: '#fdba74', renewable: false, fossil: true },
	{ type: 'FossilGasPower', label: 'Fossil gas', color: '#f97316', renewable: false, fossil: true },
	{ type: 'FossilHardCoal', label: 'Hard coal', color: '#57534e', renewable: false, fossil: true },
	{ type: 'OtherPower', label: 'Other', color: '#94a3b8', renewable: false, fossil: false }
];

export const MIX = 'ElectricityMix';
export const LOAD = 'ElectricityLoad';
const sourceTypes = new Set<string>(SOURCES.map((source) => source.type));

/** One row per (time bucket, type). `value` is MWh for hours/days and GWh for months/years. */
export type EnergyRow = {
	t: number;
	type: string;
	value: number;
	pct?: number | null;
	ef?: number | null;
	hours?: number;
	expected?: number;
};

export type Bucket = {
	t: number;
	mix: number | null;
	load: number | null;
	ef: number | null;
	sources: Partial<Record<SourceType, { value: number; pct: number | null }>>;
	sum: number;
	hours?: number;
	/** Hours in the period (23 or 25 on DST change days). */
	expected?: number;
	/** The source rows don't add up to the NED total, so the bucket is still being filled in. */
	incomplete: boolean;
};

/** Group rows into buckets ordered by time. A bucket is incomplete when its sources sum to
 * less than 98% (or more than 102%) of the published total. */
export function toBuckets(rows: readonly EnergyRow[]): Bucket[] {
	const buckets = new Map<number, Bucket>();
	for (const row of rows) {
		let bucket = buckets.get(row.t);
		if (!bucket) {
			bucket = {
				t: row.t,
				mix: null,
				load: null,
				ef: null,
				sources: {},
				sum: 0,
				incomplete: false
			};
			buckets.set(row.t, bucket);
		}
		if (row.hours !== undefined) bucket.hours = Math.max(bucket.hours ?? 0, row.hours);
		if (row.expected !== undefined) bucket.expected = row.expected;
		if (row.type === MIX) {
			bucket.mix = row.value;
			bucket.ef = row.ef ?? null;
		} else if (row.type === LOAD) bucket.load = row.value;
		else if (sourceTypes.has(row.type)) {
			bucket.sources[row.type as SourceType] = { value: row.value, pct: row.pct ?? null };
			bucket.sum += row.value;
		}
	}
	const list = [...buckets.values()].sort((a, b) => a.t - b.t);
	for (const bucket of list) {
		bucket.incomplete =
			bucket.mix === null ? bucket.sum === 0 : Math.abs(bucket.sum / bucket.mix - 1) > 0.02;
	}
	return list;
}

export type Snapshot = {
	t: number;
	total: number;
	load: number | null;
	ef: number | null;
	renewableShare: number;
	lowCarbonShare: number;
	fossilShare: number;
	sources: {
		type: SourceType;
		label: string;
		color: string;
		value: number;
		share: number;
		utilization: number | null;
	}[];
};

/** The latest complete bucket, broken down by source. */
export function latestSnapshot(buckets: readonly Bucket[]): Snapshot | null {
	const bucket = [...buckets]
		.reverse()
		.find((candidate) => !candidate.incomplete && candidate.sum > 0);
	if (!bucket) return null;
	const total = bucket.sum;
	const share = (filter: (source: Source) => boolean) =>
		SOURCES.filter(filter).reduce(
			(sum, source) => sum + (bucket.sources[source.type]?.value ?? 0),
			0
		) / total;
	return {
		t: bucket.t,
		total,
		load: bucket.load,
		ef: bucket.ef,
		renewableShare: share((source) => source.renewable),
		lowCarbonShare: share((source) => source.renewable || source.type === 'Nuclear'),
		fossilShare: share((source) => source.fossil),
		sources: SOURCES.map((source) => {
			const entry = bucket.sources[source.type];
			return {
				type: source.type,
				label: source.label,
				color: source.color,
				value: entry?.value ?? 0,
				share: (entry?.value ?? 0) / total,
				utilization: entry?.pct ?? null
			};
		}).sort((a, b) => b.value - a.value)
	};
}

/** Insert empty buckets so charts show gaps where the collector missed data. */
export function fillGaps(
	buckets: readonly Bucket[],
	step: number
): (Bucket | { t: number; missing: true })[] {
	const out: (Bucket | { t: number; missing: true })[] = [];
	for (const bucket of buckets) {
		const previous = out.at(-1);
		if (previous)
			for (let t = previous.t + step; t < bucket.t; t += step) out.push({ t, missing: true });
		out.push(bucket);
	}
	return out;
}

/** Hours missing between consecutive buckets, as [from, to) ranges in epoch ms. */
export function gaps(
	times: readonly number[],
	step = 3_600_000
): { from: number; to: number; hours: number }[] {
	const result = [];
	for (let index = 1; index < times.length; index++) {
		const missing = Math.round((times[index] - times[index - 1]) / step) - 1;
		if (missing > 0)
			result.push({ from: times[index - 1] + step, to: times[index], hours: missing });
	}
	return result;
}

/** Map a date onto leap year 2000 so different years can share one seasonal x axis. */
export function seasonalTime(day: string) {
	const [, month, date] = day.split('-').map(Number);
	return Date.UTC(2000, month - 1, date);
}