import type { DemographicAnalysis } from '../components/demographic-evidence';

type Series = DemographicAnalysis['territories'][number]['series'][number];
type Row = Series['values'][number];
const children = ['0-4', '5-9', '10-14'];
const adults = [
    '15-19',
    '20-24',
    '25-29',
    '30-34',
    '35-39',
    '40-44',
    '45-49',
    '50-54',
    '55-59',
    '60-64',
];

// Display-only derivation. Original decimals, persisted evidence and fiscal calculations are untouched.
function numeric(row: Row | undefined): number | null {
    if (
        !row ||
        !['pessoas', 'persons'].includes(row.unit) ||
        !/^\d+(\.\d+)?$/.test(row.value)
    )
        return null;
    const n = Number(row.value);
    return Number.isFinite(n) && n <= Number.MAX_SAFE_INTEGER ? n : null;
}
function one(rows: Row[], age: string, residence = 'all'): Row | undefined {
    const found = rows.filter(
        (r) =>
            r.indicator === 'population' &&
            r.age_group === age &&
            r.residence === residence,
    );
    return found.length === 1 ? found[0] : undefined;
}
export const populationLabel = (n: number | null) =>
    n === null
        ? 'Sem dados'
        : new Intl.NumberFormat('pt-MZ', { maximumFractionDigits: 0 }).format(
              n,
          );
export const percentageLabel = (n: number | null) =>
    n === null
        ? 'Sem dados'
        : new Intl.NumberFormat('pt-MZ', {
              maximumFractionDigits: 1,
              minimumFractionDigits: 1,
          }).format(n) + '%';

export function demographicReading(series: Series, start: number, end: number) {
    function year(year: number) {
        const rows = series.values.filter((r) => r.year === year);
        const totalRow = one(rows, 'all');
        const total = numeric(totalRow);
        const compatible = (r: Row | undefined) =>
            r &&
            totalRow &&
            r.unit === totalRow.unit &&
            r.data_kind === totalRow.data_kind;
        const part = (age: string, residence = 'all') => {
            const r = one(rows, age, residence);
            return compatible(r) ? numeric(r) : null;
        };
        const sum = (ages: string[]) => {
            const values = ages.map((age) => part(age));
            return values.every((v) => v !== null)
                ? values.reduce<number>((a, v) => a + (v ?? 0), 0)
                : null;
        };
        const share = (n: number | null) =>
            total !== null && total > 0 && n !== null && n <= total
                ? (n / total) * 100
                : null;
        const urban = part('all', 'urban'),
            rural = part('all', 'rural');
        const residenceReconciled =
            total !== null &&
            urban !== null &&
            rural !== null &&
            Math.abs(urban + rural - total) <=
                Math.max(0.000001, total * 1e-10);
        const under15 = sum(children),
            age15to64 = sum(adults);
        return {
            year,
            total,
            kind: totalRow?.data_kind,
            unit: totalRow?.unit,
            urban,
            rural,
            urbanShare: residenceReconciled ? share(urban) : null,
            ruralShare: residenceReconciled ? share(rural) : null,
            under15,
            under15Share: share(under15),
            age15to64,
            age15to64Share: share(age15to64),
        };
    }
    const first = year(start),
        last = year(end);
    const comparable =
        end > start &&
        first.total !== null &&
        last.total !== null &&
        first.kind === last.kind &&
        first.unit === last.unit;
    const delta = comparable ? last.total! - first.total! : null;
    const growth =
        delta !== null && first.total! > 0
            ? (delta / first.total!) * 100
            : null;
    return {
        first,
        last,
        delta,
        growth,
        years: Array.from({ length: end - start + 1 }, (_, i) =>
            year(start + i),
        ),
    };
}