import type { Asset, InvoiceLine, MonthlyIncome, MonthlyRunningCost } from "./data";
import { computeProfit, type ProfitOptions } from "./profit";

export type IncomeRow = {
  id: string;
  code: string;
  name: string;
  months: (number | null)[];  // Part A.2: null = no data (forecast), 0 = earned zero
  fixedMonths: (number | null)[];
  runningMonths: (number | null)[];
  profit: number[];
  income: number;
  fixed: number;
  running: number;
  ytdProfit: number;
  lastActualMonth: number;  // Part A.3: clip x-axis
  // Machines the client has stood down. They still hold their history, so they are kept
  // in the data and filtered in the view rather than dropped here — /income defaults to
  // active only, but the client can switch to All or Inactive.
  isActive: boolean;
  // Portion of `income` that came from invoices, and how much of that is VAT.
  // Booked amounts are VAT-inclusive (see lib/invoice-booking-policy.json), so without
  // this the per-machine figure is not explainable.
  invoiceIncome: number;
  invoiceVat: number;
  // Every invoice that contributed to this machine, so the card can show the combined
  // total and break it down by invoice and site without another query.
};

// Per Part A.2: months beyond lastActualMonth are null in `months`/`fixedMonths`/`runningMonths`.
// `running` is derived from monthly_running_costs; null means we have no running data for that month.
export function buildIncomeRows(
  assets: Asset[],
  income: MonthlyIncome[],
  running?: MonthlyRunningCost[],
  profitOpts: ProfitOptions = {},
  // Invoice line items, used only to attribute the VAT already inside each booked
  // amount back to the machine that earned it.
  invoiceLines?: InvoiceLine[],
): IncomeRow[] {
  // Determine the last actual month globally (Part A.2/A.3)
  const lastActualMonth = income.reduce((m, r) => r.income > 0 && r.month > m ? r.month : m, 0);

  const byAsset = new Map<string, IncomeRow>();
  for (const a of assets) {
    if (!a.code) continue;
    byAsset.set(a.id, {
      id: a.id, code: a.code, name: a.name,
      isActive: a.is_active !== false,
      months: Array(12).fill(null),
      fixedMonths: Array(12).fill(null),
      runningMonths: Array(12).fill(null),
      profit: Array(12).fill(0),
      income: 0, fixed: 0, running: 0, ytdProfit: 0,
      lastActualMonth,
      invoiceIncome: 0, invoiceVat: 0,
    });
  }
  for (const r of income) {
    const row = byAsset.get(r.asset);
    if (!row) continue;
    const i = r.month - 1;
    // Part A.2: only null out months BEYOND the last actual month. Months up to and including
    // lastActualMonth get their real value (which may be 0 — a real plotted zero).
    //
    // ACCUMULATE, do not assign: a machine can have several income rows in one month —
    // a workbook row plus one per invoice line booked to it. Assigning made the cell show
    // only the last row, so SS01 (two September invoices) displayed R20,700 while its own
    // YTD total included both (R35,305), and the September column total came out short.
    if (r.month <= lastActualMonth) {
      row.months[i] = (row.months[i] ?? 0) + r.income;
      row.fixedMonths[i] = (row.fixedMonths[i] ?? 0) + r.fixed_expenses;
    }
    row.income += r.income;
    row.fixed += r.fixed_expenses;
  }
  // Per Part 1.5: running cost is derived from monthly_running_costs, not stored on income.
  for (const c of running ?? []) {
    const row = byAsset.get(c.asset);
    if (!row) continue;
    row.running += c.amount;
    if (c.month <= lastActualMonth) {
      row.runningMonths[c.month - 1] = c.amount;
    }
  }

  // Per-month profit is computed ONCE, after income and running have both been
  // accumulated, so it reflects the whole month rather than whichever row happened to be
  // read last. Previously this lived inside the two loops above and inherited the same
  // last-write-wins bug.
  for (const row of byAsset.values()) {
    for (let i = 0; i < 12; i++) {
      if (i + 1 > lastActualMonth) continue;
      row.profit[i] = computeProfit(
        {
          income: row.months[i] ?? 0,
          fixed: row.fixedMonths[i] ?? 0,
          running: row.runningMonths[i] ?? 0,
        },
        profitOpts,
      );
    }
  }
  // Attribute invoice-derived income and its embedded VAT per machine.
  for (const l of invoiceLines ?? []) {
    const row = byAsset.get(l.booked_asset);
    if (!row) continue;
    row.invoiceIncome += l.total_incl || 0;
    row.invoiceVat += l.vat || 0;
  }

  for (const row of byAsset.values()) {
    row.ytdProfit = computeProfit({ income: row.income, fixed: row.fixed, running: row.running }, profitOpts);
  }
  return Array.from(byAsset.values());
}

export type RunningRow = {
  id: string;
  code: string;
  name: string;
  months: number[];
  ytd: number;
};

export function buildRunningRows(
  assets: Asset[],
  costs: MonthlyRunningCost[]
): RunningRow[] {
  const byAsset = new Map<string, RunningRow>();
  for (const a of assets) {
    if (!a.code) continue;
    byAsset.set(a.id, {
      id: a.id, code: a.code, name: a.name,
      months: Array(12).fill(0),
      ytd: 0,
    });
  }
  for (const c of costs) {
    const row = byAsset.get(c.asset);
    if (!row) continue;
    row.months[c.month - 1] = c.amount;
    row.ytd += c.amount;
  }
  return Array.from(byAsset.values());
}