import type { Asset, BookedLine, Invoice, Site } from "./data";
import { isInternalParty } from "./invoice-party";

// A line whose invoice is missing cannot be classified, so it must not be counted as
// internal by accident. An invoice with no debtor is never internal — see
// lib/invoice-party.ts — so an empty placeholder counts as external.
const EMPTY_INVOICE = { debtor: "", debtor_no: "" } as Pick<Invoice, "debtor" | "debtor_no">;

// Sites are DERIVED from the invoices: each distinct invoice site becomes a site.
// They are not typed in by hand, so this is the only place that creates them.
//
// ONLY INTERNAL invoices create sites. An external invoice is billed by a third party and
// its description text is not a place name — "Crane Truck Hire 17 September 2026 Move
// containers" yielded a site literally called "Move containers", which then appeared on
// /sites and in the plant register's site filter. The name an external invoice carries is
// its supplier, which is not a site, so it is never registered as one. See
// lib/invoice-party-policy.json for how the two halves are told apart.
//
// Existing records are never deleted and never overwritten — a site may carry notes
// and may have lines booked to it, so removing one would orphan that history. A
// invoice site that disappears simply stops appearing in new invoices.
export async function syncSitesFromInvoices(pb: any, invoices: Invoice[]): Promise<Site[]> {
  const existing = (await pb.collection("sites").getFullList()) as Site[];
  const byName = new Map(existing.map((s: Site) => [(s.name || "").toLowerCase(), s]));

  const wanted = [
    ...new Set(
      invoices
        .filter((i) => isInternalParty(i))
        .map((i) => (i.site || "").trim())
        .filter(Boolean),
    ),
  ];
  for (const name of wanted) {
    if (byName.has(name.toLowerCase())) continue;
    try {
      const created = await pb.collection("sites").create({ name, is_active: true });
      byName.set(name.toLowerCase(), created as Site);
    } catch {
      // A concurrent upload may have created it first; the catch is a no-op.
    }
  }
  return byName.size ? Array.from(byName.values()) : existing;
}

export type SiteInvoiceRef = {
  id: string;
  invoiceNo: string;
  invoiceDate: string;
  periodFrom: string;
  periodTo: string;
  /** This site's share of the invoice — the sum of the site's lines, not the header
   *  total. Equal to the header total today, because an invoice carries one site, but
   *  summing lines keeps it right if an invoice ever spans two. */
  totalIncl: number;
  hasPdf: boolean;
};

/** One month of billing for a site. A month holds one or more invoices. */
export type SiteMonth = {
  key: string;   // "2026-09"
  year: number;
  month: number; // 1-12
  totalExcl: number;
  vat: number;
  totalIncl: number;
  invoices: SiteInvoiceRef[];
};

export type SiteSummary = {
  id: string;
  name: string;
  /** Income, ex VAT — what actually lands in the P&L. */
  revenueExcl: number;
  vat: number;
  /** What the debtors were billed in total. */
  revenueIncl: number;
  invoices: { id: string; invoiceNo: string; invoiceDate: string; totalIncl: number }[];
  /** The calendar year the `months` series covers, so the chart is never ambiguous. */
  year: number;
  /** 12 slots of billed amount incl VAT. null = no invoice that month, which is
   *  different from a billed zero. Same convention as IncomeRow.months. */
  months: (number | null)[];
  /** Only the months that actually have an invoice, ascending. Drives the expanded
   *  panel, so a month with no billing is simply absent rather than a zero row. */
  monthly: SiteMonth[];
  machineCount: number;
  lineCount: number;
  /** True once the site has map coordinates. Carried on the summary so the table —
   *  a client component — can render the marker without also receiving the site list. */
  pinned: boolean;
  /** Lines with neither a plant item nor a site — the work still outstanding. */
  unbookedCount: number;
  unbookedAmount: number;
  /** The outstanding lines split by which half of the register they live on. The site's
   *  "assign them" link has to pick a page, and the register is split in two — a site
   *  whose only unbooked lines are on external invoices must be sent to the external
   *  page, or the link lands on a page that does not contain them. */
  unbookedInternalCount: number;
  unbookedExternalCount: number;
};

/** The year the chart should show: the most recent one any invoice was booked into.
 *  Scrolling forward a year re-bases every series without a schema change. */
export function latestInvoiceYear(invoices: Invoice[]): number {
  return invoices.reduce((y, i) => (i.booked_year > y ? i.booked_year : y), new Date().getUTCFullYear());
}

// Which month an invoice is billed in.
//
// `booked_month`/`booked_year` are already written by the seed from the month of
// `period_to` (scripts/seed.mjs), which is the same rule that posts the income into
// monthly_income. Reusing that field is what keeps a site's month here equal to the
// same month on /income — a site chart that disagreed with the income screen would be
// worse than no chart. The date fallback only covers a record imported before those
// fields existed.
function invoiceMonth(inv: Invoice): { year: number; month: number } {
  if (inv.booked_month >= 1 && inv.booked_month <= 12 && inv.booked_year) {
    return { year: inv.booked_year, month: inv.booked_month };
  }
  const d = inv.period_to || inv.invoice_date;
  if (d) {
    const dt = new Date(d);
    if (!Number.isNaN(dt.getTime())) return { year: dt.getUTCFullYear(), month: dt.getUTCMonth() + 1 };
  }
  return { year: 0, month: 0 };
}

// Per-site revenue and VAT, derived by walking invoice lines through their invoice.
//
// ONLY INTERNAL invoices count towards a site. An external invoice's "site" is its
// supplier, not a place, so letting it in here is what put "Move containers" on /sites as
// if it were a yard. Its income is not lost — it is booked to a machine and still shows on
// /income and /charts; it simply is not a site.
export function buildSiteSummaries(
  sites: Site[],
  invoices: Invoice[],
  lines: BookedLine[],
  assets: Asset[],
): SiteSummary[] {
  const invById = new Map(invoices.map((i) => [i.id, i]));
  const year = latestInvoiceYear(invoices);

  return sites
    .map((site) => {
      const siteLines = lines.filter(
        (l) => invById.get(l.invoice)?.site === site.name && isInternalParty(invById.get(l.invoice)!),
      );
      const revExcl = siteLines.reduce((s, l) => s + (l.amount_excl || 0), 0);
      const vat = siteLines.reduce((s, l) => s + (l.vat || 0), 0);
      const incl = siteLines.reduce((s, l) => s + (l.total_incl || 0), 0);

      const invMap = new Map<string, { id: string; invoiceNo: string; invoiceDate: string; totalIncl: number }>();
      for (const l of siteLines) {
        const inv = invById.get(l.invoice);
        if (inv) invMap.set(inv.id, { id: inv.id, invoiceNo: inv.invoice_no, invoiceDate: inv.invoice_date, totalIncl: inv.total_incl });
      }

      // Bucket the same lines by billing month. One invoice contributes several lines to
      // a site (PHI 166 has five), so an invoice is listed ONCE per month and its amount
      // accumulates across those lines — otherwise a site would show a card per line.
      const buckets = new Map<string, SiteMonth>();
      const refsByMonth = new Map<string, Map<string, SiteInvoiceRef>>();
      for (const l of siteLines) {
        const inv = invById.get(l.invoice);
        if (!inv) continue;
        const m = invoiceMonth(inv);
        if (!m.year || !m.month) continue;
        const key = `${m.year}-${String(m.month).padStart(2, "0")}`;
        let bucket = buckets.get(key);
        if (!bucket) {
          bucket = { key, year: m.year, month: m.month, totalExcl: 0, vat: 0, totalIncl: 0, invoices: [] };
          buckets.set(key, bucket);
          refsByMonth.set(key, new Map());
        }
        bucket.totalExcl += l.amount_excl || 0;
        bucket.vat += l.vat || 0;
        bucket.totalIncl += l.total_incl || 0;

        const refs = refsByMonth.get(key)!;
        const seen = refs.get(inv.id);
        if (seen) {
          seen.totalIncl += l.total_incl || 0;
        } else {
          refs.set(inv.id, {
            id: inv.id,
            invoiceNo: inv.invoice_no,
            invoiceDate: inv.invoice_date,
            periodFrom: inv.period_from,
            periodTo: inv.period_to,
            totalIncl: l.total_incl || 0,
            hasPdf: Boolean(inv.source_pdf),
          });
        }
      }

      const monthly = Array.from(buckets.values())
        .sort((a, b) => a.key.localeCompare(b.key))
        .map((b) => ({
          ...b,
          invoices: Array.from(refsByMonth.get(b.key)!.values()).sort((x, y) => x.invoiceNo.localeCompare(y.invoiceNo)),
        }));

      // 12-slot series for the sparkline. Months from OTHER years are dropped rather
      // than folded in — a Dec-2025 invoice must not paint a point on Jan.
      const months: (number | null)[] = Array(12).fill(null);
      for (const b of monthly) if (b.year === year) months[b.month - 1] = b.totalIncl;

      const unbooked = siteLines.filter((l) => !l.isBooked && !l.booked_site);
      return {
        id: site.id,
        name: site.name,
        revenueExcl: revExcl,
        vat,
        revenueIncl: incl,
        invoices: Array.from(invMap.values()).sort((a, b) => b.invoiceDate.localeCompare(a.invoiceDate)),
        year,
        months,
        monthly,
        machineCount: new Set(siteLines.map((l) => l.booked_asset).filter(Boolean)).size,
        lineCount: siteLines.length,
        pinned: Boolean(site.latitude),
        unbookedCount: unbooked.length,
        unbookedAmount: unbooked.reduce((s, l) => s + (l.total_incl || 0), 0),
        unbookedInternalCount: unbooked.filter((l) => isInternalParty(invById.get(l.invoice) ?? EMPTY_INVOICE)).length,
        unbookedExternalCount: unbooked.filter((l) => !isInternalParty(invById.get(l.invoice) ?? EMPTY_INVOICE)).length,
      };
    })
    .filter((s) => s.invoices.length > 0 || s.lineCount > 0)
    .sort((a, b) => b.revenueIncl - a.revenueIncl);
}

// Sites already taken by another line that has no plant item.
// One container per site: once a site holds a container, the next container's
// picker must not offer it, so the outstanding containers spread across sites
// instead of piling onto the first one.
export function takenSiteIdsFor(lines: BookedLine[], exceptLineId: string): Set<string> {
  const taken = new Set<string>();
  for (const l of lines) {
    if (l.id === exceptLineId) continue;
    if (l.booked_site && !l.booked_asset) taken.add(l.booked_site);
  }
  return taken;
}

// Auto-allocation for a line that matches no plant item.
//
// The invoices print a generic code for hire containers ("MPLANT05 Storage Container")
// that the plant register does not carry. Each site records the container it hires, and
// the code the invoice uses for it. So a container line arriving on an invoice for a site
// that has a matching container is booked to that container rather than left stuck.
//
// The lookup is against THIS invoice's site only — two sites can both hire
// "MPLANT05" units, and each line must go to the unit actually on its own site.
export function findSiteContainer(
  sites: Site[],
  siteName: string,
  machineCode: string,
): Site | null {
  const wanted = (machineCode || "").trim().toLowerCase();
  if (!wanted || !siteName) return null;
  return (
    sites.find(
      (s) =>
        (s.name || "").toLowerCase() === (siteName || "").toLowerCase() &&
        (s.container_code || "").trim().toLowerCase() === wanted &&
        Boolean(s.container_asset),
    ) ?? null
  );
}

/**
 * Fold the site name an invoice prints onto the name the register already uses.
 *
 * The supplier abbreviates: PHI 179 reads "Crane Truck Hire Sep 2026 Cosmo" for the
 * site every other invoice calls "Cosmo City". Taking that literally would create a
 * SECOND site called "Cosmo" — `syncSitesFromInvoices` derives sites from the invoice
 * wording — and the same customer would then split across two places on /sites, with
 * neither row showing the whole picture.
 *
 * Only an unambiguous whole-word match folds, and only in ONE direction: the invoice's
 * name must be shorter and be a whole-word prefix of a site already in the register.
 * That is what an abbreviation looks like. The reverse — folding "Cosmo City Extension"
 * onto "Cosmo City" — would silently merge two genuinely different places, so it is not
 * done; an unknown name keeps the invoice's own wording and a new site is still recorded
 * as new.
 */
export function resolveSiteName(raw: string, known: string[]): string {
  const t = (raw || "").trim();
  if (!t) return "";
  const low = t.toLowerCase();
  for (const k of known) {
    const kk = (k || "").trim().toLowerCase();
    if (!kk) continue;
    if (kk === low) return k;
    if (kk.startsWith(`${low} `)) return k;
  }
  return t;
}