import { readFile } from 'node:fs/promises';
import pg from 'pg';
import { isInfantFood, maxJsonBytes } from './european.ts';
import { importDrafts, toNumber } from './national.ts';
import type { Draft, NutrientKey, Parsed, ValueType } from './national.ts';

// Livsmedelsdatabasen (Swedish Food Agency, Livsmedelsverket), Sweden. Open data under Creative Commons
// Attribution 4.0 ("The Swedish Food Agency must be stated as the source."), delivered by the agency's public
// API; scripts/fetch-food-livsmedelsverket.ts saves the food list and every food's nutrient values, in English,
// into one JSON file. Each value carries EuroFIR value-type, method-type and acquisition-type codes.
export const livsmedelsverketSourceName = 'Livsmedelsdatabasen, Livsmedelsverket (Swedish Food Agency)';
export const livsmedelsverketAttribution = 'Livsmedelsverket (Swedish Food Agency), The Swedish Food Database (Livsmedelsdatabasen). CC BY 4.0.';
export const livsmedelsverketLanguage = 'en';

// EuroFIR code + unit -> key. Carbohydrate is "Carbohydrates, available" (FD-11 `available`).
const nutrients: Record<string, NutrientKey> = {
  'ENERC kcal': 'enerc_kcal', 'ENERC kJ': 'enerc_kj', 'PROT g': 'procnt_g', 'FAT g': 'fat_g', 'CHO g': 'chocdf_g',
  'FIBT g': 'fibtg_g', 'SUGAR g': 'sugar_g', 'SUGAD g': 'sugad_g', 'FASAT g': 'fasat_g', 'NA mg': 'na_mg',
  'CHORL mg': 'chole_mg', 'K mg': 'k_mg', 'CA mg': 'ca_mg', 'FE mg': 'fe_mg', 'VITD µg': 'vitd_ug', 'ALC g': 'alc_g',
  'CAFFN mg': 'caffn_mg', 'WATER g': 'water_g',
};

type Value = { euroFIRkod?: string; enhet?: string; varde?: number; vardetypkod?: string; metodtypkod?: string;
  ursprungkod?: string; matrisenhetkod?: string };

// FD-07 type from the EuroFIR codes of the value. Below-limit values and values without any code stay
// unknown. A logical zero or a trace stated as 0 is `assumed_zero`. A value taken from another food
// composition table or paper is `borrowed`, one from a label `label`; otherwise the method type decides.
export function livsmedelsverketType(value: Value): ValueType | null {
  const { vardetypkod: kind, metodtypkod: method, ursprungkod: origin } = value;
  if (kind === 'BL' || kind === 'BQ') return null;
  if (kind === 'LZ' || kind === 'TR') return value.varde === 0 ? 'assumed_zero' : null;
  if (origin === 'F' || origin === 'C' || origin === 'P') return 'borrowed';
  if (origin === 'L') return 'label';
  if (method === 'A' || method === 'AG' || method === 'D') return 'analytic';
  if (method && ['R', 'S', 'T', 'CG', 'G', 'P'].includes(method)) return 'calculated';
  if (method && ['K', 'I', 'IG', 'O'].includes(method)) return 'imputed';
  if (method === 'U') return value.varde === 0 ? 'assumed_zero' : 'imputed';
  return null;
}

export function parseLivsmedelsverket(bytes: Buffer): Parsed {
  if (bytes.length > maxJsonBytes) throw new Error('Livsmedelsverket file is too large');
  const input = JSON.parse(bytes.toString('utf8'));
  if (!Array.isArray(input?.foods)) throw new Error('Livsmedelsverket file has no foods');
  const counts = new Map<number, number>();
  for (const food of input.foods) counts.set(food.nummer, (counts.get(food.nummer) ?? 0) + 1);

  const out: Parsed = { drafts: [], skipped: [] };
  for (const food of input.foods) {
    const id = Number.isInteger(food.nummer) ? String(food.nummer) : null;
    if (!id) { out.skipped.push({ recordId: null, reason: 'missing source identifier' }); continue; }
    if (counts.get(food.nummer) !== 1) { out.skipped.push({ recordId: id, reason: 'duplicate source identifier' }); continue; }
    const name = typeof food.namn === 'string' ? food.namn.replace(/\s+/g, ' ').trim() : '';
    if (!name) { out.skipped.push({ recordId: id, reason: 'no English name' }); continue; }
    if (isInfantFood(name)) { out.skipped.push({ recordId: id, reason: 'baby food (C-23)' }); continue; }
    const rows: Value[] = Array.isArray(food.naringsvarden) ? food.naringsvarden : [];
    if (!rows.length) { out.skipped.push({ recordId: id, reason: 'no composition rows' }); continue; }

    const values: Draft['values'] = {};
    const kinds: Draft['kinds'] = {};
    const seen = new Set<NutrientKey>();
    let refuse: number | null = null;
    for (const row of rows) {
      if (row.euroFIRkod === 'WASTE' && row.enhet === '%' && typeof row.varde === 'number' && row.varde >= 0 && row.varde <= 100)
        refuse = row.varde / 100;
      const key = nutrients[`${row.euroFIRkod} ${row.enhet}`];
      if (!key || (row.matrisenhetkod ?? 'W') !== 'W') continue;
      // Two rows for one nutrient cannot both be right; neither is used.
      if (seen.has(key)) { delete values[key]; delete kinds[key]; continue; }
      seen.add(key);
      const value = toNumber(String(row.varde));
      const type = livsmedelsverketType(row);
      if (value === null || value < 0 || !type) continue;
      values[key] = value; kinds[key] = type;
    }

    const added: Record<string, unknown> = { name_language: livsmedelsverketLanguage, native_language: 'sv',
      food_type: food.livsmedelsTyp ?? null, scientific_name: food.vetenskapligtNamn || null, project: food.projekt ?? null };
    if (refuse !== null) added.refuse_fraction = refuse;
    out.drafts.push({
      recordId: id, name, basis: '100g', carbohydrateDefinition: 'available', values, kinds, measures: [], added,
      raw: Buffer.from(JSON.stringify(food)),
    });
  }
  return out;
}

export async function importLivsmedelsverketFile(client: pg.Client, path: string, releasedAt: string) {
  return importDrafts(client, { src: 'SRC-12', market: 'SE', family: 'open' },
    parseLivsmedelsverket(await readFile(path)), releasedAt, livsmedelsverketSourceName);
}