import type { Asset, FinancingTerm, InsuranceRate, InvoiceLine, MonthlyIncome, MonthlyRunningCost, Operator } from "./data";
import { computeProfit, type ProfitOptions } from "./profit";
import { currentRate, monthlyCost, validatePeriods, type RatePeriod } from "./insurance";
import { financeCalc, toInput, type FinanceCalc } from "./financing";
import { exclFromIncl } from "./purchase-booking";
import { COST_KINDS, type MachineCosts } from "./running-costs";

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;
  /** Per month, VAT-INCLUSIVE: the workbook figure plus any purchased parts. */
  months: number[];
  ytd: number;
  /** Per month, net of VAT at the confirmed rate. Shown under `months`, never instead of it. */
  monthsExcl: number[];
  ytdExcl: number;
  /** The purchased portion of each month, so the Overview can say what came from where. */
  purchasesIncl: number[];
  /** False means NO cost of any kind is recorded for that month — which is different
   *  from a month that genuinely costs R0. */
  knownMonths: boolean[];
  byKind: { repairs: number[]; purchases: number[]; insurance: number[]; finance: number[] };
};

export function buildRunningRows(
  assets: Asset[],
  // All four cost kinds per machine per month — repairs, purchases, insurance and
  // finance, assembled in lib/running-costs.ts. Everything a vehicle costs to run.
  costs?: Map<string, MachineCosts>,
): 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,
      // Net of VAT at the confirmed rate, kept alongside so the Overview can show
      // incl above excl rather than making a reader back the VAT out.
      monthsExcl: Array(12).fill(0),
      ytdExcl: 0,
      purchasesIncl: Array(12).fill(0),
      knownMonths: Array(12).fill(false),
      byKind: { repairs: Array(12).fill(0), purchases: Array(12).fill(0), insurance: Array(12).fill(0), finance: Array(12).fill(0) },
    });
  }
  if (!costs) return Array.from(byAsset.values());

  for (const [assetId, kinds] of costs) {
    const row = byAsset.get(assetId);
    if (!row) continue;
    for (let i = 0; i < 12; i++) {
      let incl = 0;
      for (const k of COST_KINDS) {
        const v = kinds[k][i] ?? 0;
        incl += v;
        row.byKind[k][i] += v;
      }
      if (incl <= 0) continue;
      row.months[i] += incl;
      row.ytd += incl;
      row.purchasesIncl[i] += kinds.purchases[i] ?? 0;
      row.monthsExcl[i] += exclFromIncl(incl);
      row.ytdExcl += exclFromIncl(incl);
      row.knownMonths[i] = true;
    }
  }
  return Array.from(byAsset.values());
}

export type FinancingRow = {
  id: string;
  code: string;
  name: string;
  plant: string;
  /** Monthly instalment incl VAT, straight from the rate sheet. Not editable in the app. */
  installment: number;
  startYear: number;
  startMonth: number;
  endYear: number;
  endMonth: number;
  isSettled: boolean;
  calc: FinanceCalc;
};

/**
 * One row per finance agreement, with its settlement maths already resolved.
 *
 * A machine with no agreement is left OUT, as everywhere else here: it was not
 * financed, which is a different statement from being financed at R0.
 */
export function buildFinancingRows(
  assets: Asset[],
  terms: FinancingTerm[],
  now: { year: number; month: number },
): FinancingRow[] {
  const byId = new Map(assets.map((a) => [a.id, a]));
  const out: FinancingRow[] = [];
  for (const t of terms) {
    const a = byId.get(t.asset);
    if (!a || !a.code) continue;
    out.push({
      id: t.id,
      code: a.code,
      name: a.name,
      plant: t.plant || "",
      installment: t.installment || 0,
      startYear: t.start_year || 0,
      startMonth: t.start_month || 0,
      endYear: t.end_year || 0,
      endMonth: t.end_month || 0,
      isSettled: Boolean(t.is_settled),
      calc: financeCalc(toInput(t, now)),
    });
  }
  return out;
}

export type OperatorRow = {
  /** null on a row that represents an operator with no machine of their own. */
  machineId: string | null;
  machineCode: string;
  machineName: string;
  operatorId: string | null;
  operatorName: string;
  employeeCode: string;
  rate: number | null;
  /** True when this row exists because of an operator, not a machine. */
  isUnassignedOperator: boolean;
};

/**
 * The operator register, keyed on the PLANT REGISTER but SCOPED to the sheet.
 *
 * Only machines the client's operator sheet lists appear — twenty vehicles. The
 * register holds forty-one coded machines and the difference (containers, generators,
 * truck trailers) can never have a person allocated to them, so listing them would
 * present twenty-odd permanent blanks as if they were staffing gaps. The machine's
 * NAME and CODE still come from the register, so the list stays linked to it.
 *
 * Every in-scope machine gets a row, whether or not anyone is on it: an unstaffed
 * machine is exactly what a reader needs to see. A machine with no operator carries
 * blank operator cells; that is NOT the same as an operator with no rate.
 *
 * Operators the sheet gave no machine get their own row at the end with blank machine
 * cells, because they are people on the payroll and must not vanish from the register.
 *
 * Assets with NO code are skipped even if flagged: the sheet addresses machines by
 * P/Unit, so an uncoded entry cannot be pointed at.
 */
export function buildOperatorRows(assets: Asset[], operators: Operator[]): OperatorRow[] {
  const byMachine = new Map<string, Operator>();
  const unassigned: Operator[] = [];

  for (const o of operators) {
    if (o.asset) byMachine.set(o.asset, o);
    else unassigned.push(o);
  }

  // The sheet decides the baseline, but a machine someone has been allocated to ALWAYS
  // appears — otherwise adding an operator to a machine that was not on the sheet would
  // look like it silently did nothing. Adding a person must always be visible.
  const inScope = assets.filter(
    (a) => a.code && (a.on_operator_sheet || byMachine.has(a.id)),
  );

  const rows: OperatorRow[] = inScope.map((a) => {
    const op = byMachine.get(a.id);
    return {
      machineId: a.id,
      machineCode: a.code,
      machineName: a.name,
      operatorId: op?.id ?? null,
      operatorName: op?.name ?? "",
      employeeCode: op?.employee_code ?? "",
      rate: op ? op.rate ?? null : null,
      isUnassignedOperator: false,
    };
  });

  for (const op of unassigned) {
    rows.push({
      machineId: null,
      machineCode: "",
      machineName: "",
      operatorId: op.id,
      operatorName: op.name,
      employeeCode: op.employee_code,
      rate: op.rate ?? null,
      isUnassignedOperator: true,
    });
  }
  return rows;
}

export type InsuranceRow = {
  id: string;
  code: string;
  name: string;
  // The cost per month, resolved against the premium in force THAT month.
  // `null` = no premium on record for that month — never 0 (see lib/insurance.ts).
  months: (number | null)[];
  // Sum of the months we actually know. Months with no premium are excluded rather
  // than counted as zero, so this is never quietly smaller than a full year.
  ytd: number;
  coveredMonths: number;
  currentRate: number | null;
  // The machine's premium history, newest first — the point of the page.
  periods: RatePeriod[];
  problems: string[];
};

/**
 * One row per insured machine, built from RATE PERIODS (`insurance_rates`), not from
 * `cost_lines`. The rates are the source of truth; the monthly cost lines are
 * derived from them by the seed, so reading the rates directly is what keeps this
 * page showing a premium change rather than a flat rate re-keyed twelve times.
 *
 * A machine with no rate at all is left OUT, as `buildRunningRows` does for running
 * cost: "no premium on record" is not "R0 of insurance".
 */
export function buildInsuranceRows(assets: Asset[], rates: InsuranceRate[]): InsuranceRow[] {
  const byId = new Map(assets.map((a) => [a.id, a]));
  const grouped = new Map<string, RatePeriod[]>();

  for (const r of rates) {
    const a = byId.get(r.asset);
    if (!a || !a.code) continue;
    const list = grouped.get(a.id) || [];
    list.push({ from: r.month_from, to: r.month_to || 0, rate: r.rate, source: r.source || "" });
    grouped.set(a.id, list);
  }

  const out: InsuranceRow[] = [];
  for (const [assetId, periods] of grouped) {
    const a = byId.get(assetId)!;
    const cost = monthlyCost(periods);
    const known = cost.filter((v): v is number => v !== null);
    out.push({
      id: assetId,
      code: a.code,
      name: a.name,
      months: cost,
      ytd: known.reduce((s, v) => s + v, 0),
      coveredMonths: known.length,
      currentRate: currentRate(periods)?.rate ?? null,
      // Newest first — the period you most likely came to read.
      periods: [...periods].sort((x, y) => y.from - x.from),
      problems: validatePeriods(periods),
    });
  }
  return out;
}