import { getSupabaseConfig, supabaseFetch } from './_supabase.js';
import { json } from './_session.js';

const PUBLIC_HEADERS = {
  'access-control-allow-origin': '*',
  'access-control-allow-methods': 'GET, OPTIONS',
  'access-control-allow-headers': 'content-type'
};
const POL_PRICE_URL = 'https://api.coinbase.com/v2/exchange-rates?currency=POL';

function sum(values) {
  return values.reduce((total, value) => {
    const numeric = Number(value);
    return Number.isFinite(numeric) ? total + numeric : total;
  }, 0);
}

function groupCount(rows, key) {
  return rows.reduce((acc, row) => {
    const value = row[key] || 'unknown';
    acc[value] = (acc[value] || 0) + 1;
    return acc;
  }, {});
}

function sumNativeByCurrency(rows) {
  return rows.reduce((acc, row) => {
    const amount = Number(row.amount_native);
    const currency = String(row.currency || '').trim().toUpperCase();
    if (!Number.isFinite(amount) || amount <= 0 || !currency || currency === 'USD') return acc;
    acc[currency] = Number(((acc[currency] || 0) + amount).toFixed(8));
    return acc;
  }, {});
}

async function getUsdRateByCurrency() {
  try {
    const response = await fetch(POL_PRICE_URL, {
      headers: {
        accept: 'application/json'
      }
    });
    if (!response.ok) throw new Error(`price_status_${response.status}`);
    const payload = await response.json();
    const polUsd = Number(payload?.data?.rates?.USD);
    return {
      POL: Number.isFinite(polUsd) && polUsd > 0 ? polUsd : 0
    };
  } catch (error) {
    return {
      POL: 0
    };
  }
}

function normalizeLedgerRows(rows, usdRates = {}) {
  return rows.map((row) => {
    const currency = String(row.currency || '').trim().toUpperCase();
    const nativeAmount = Number(row.amount_native);
    const explicitUsd = Number(row.amount_usd);
    const derivedUsd = (!Number.isFinite(explicitUsd) || explicitUsd <= 0)
      && Number.isFinite(nativeAmount)
      && nativeAmount > 0
      && Number.isFinite(Number(usdRates[currency]))
      && Number(usdRates[currency]) > 0
      ? Number((nativeAmount * Number(usdRates[currency])).toFixed(2))
      : explicitUsd;

    return {
      ...row,
      amount_usd: Number.isFinite(derivedUsd) && derivedUsd > 0 ? derivedUsd : 0
    };
  });
}

export async function onRequestOptions() {
  return new Response(null, { status: 204, headers: PUBLIC_HEADERS });
}

export async function onRequestGet({ env }) {
  const config = getSupabaseConfig(env);
  if (!config) {
    return json({
      ok: true,
      configured: false,
      generatedAt: new Date().toISOString(),
      totals: {
        donations: 0,
        amountUsd: 0,
        nativeByCurrency: {},
        projects: 0,
        integrations: 0
      },
      byProvider: {},
      recent: []
    }, 200, PUBLIC_HEADERS);
  }

  try {
    const usdRates = await getUsdRateByCurrency();
    const rows = await supabaseFetch(
      config,
      '/rest/v1/soulwall_ledger?select=event_id,client_id,integration_origin,provider,project_slug,project_name,tx_hash,currency,amount_usd,amount_native,network,status,confirmed_at,created_at&status=eq.confirmed&order=confirmed_at.desc.nullslast,created_at.desc&limit=1000'
    );

    const confirmed = normalizeLedgerRows(Array.isArray(rows) ? rows : [], usdRates);
    const projects = new Set(confirmed.map((row) => row.project_slug || row.project_name).filter(Boolean));
    const integrations = new Set(confirmed.map((row) => row.client_id || row.integration_origin).filter(Boolean));

    return json({
      ok: true,
      configured: true,
      generatedAt: new Date().toISOString(),
      totals: {
        donations: confirmed.length,
        amountUsd: Number(sum(confirmed.map((row) => row.amount_usd)).toFixed(2)),
        nativeByCurrency: sumNativeByCurrency(confirmed),
        projects: projects.size,
        integrations: integrations.size
      },
      byProvider: groupCount(confirmed, 'provider'),
      recent: confirmed.slice(0, 25)
    }, 200, PUBLIC_HEADERS);
  } catch (error) {
    return json({
      ok: false,
      configured: true,
      error: error?.message || 'Ledger read failed.',
      totals: {
        donations: 0,
        amountUsd: 0,
        nativeByCurrency: {},
        projects: 0,
        integrations: 0
      },
      byProvider: {},
      recent: []
    }, 500, PUBLIC_HEADERS);
  }
}