import { createFileRoute, Link } from "@tanstack/react-router";
import { useQuery } from "@tanstack/react-query";
import { supabase } from "@/integrations/supabase/client";
import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import { Label } from "@/components/ui/label";
import { ArrowLeft, Loader2, Mail, Printer } from "lucide-react";
import { useState } from "react";
import { DocHeader, SignatureLines } from "@/components/reports";
import { SCHOOL_NAME, money, monthToDateRange, schoolYearRange } from "@/lib/reports";
import { formatDate } from "@/lib/plans";

export const Route = createFileRoute("/_authenticated/invoice/$id")({
  head: () => ({ meta: [{ title: "Invoice — School Portal" }] }),
  component: InvoicePage,
});

const CATEGORY_LABEL: Record<string, string> = {
  tuition: "Tuition",
  late_pickup: "Late pickup",
  activity: "Activity",
  other: "Other",
};

function InvoicePage() {
  const { id } = Route.useParams();
  const initial = monthToDateRange();
  const [from, setFrom] = useState(initial.from);
  const [to, setTo] = useState(initial.to);

  const { data: student } = useQuery({
    queryKey: ["invoice-student", id],
    queryFn: async () =>
      (
        await supabase
          .from("students")
          .select("id, first_name, last_name, grade_level, daily_tuition_cents, classes(name)")
          .eq("id", id)
          .single()
      ).data,
  });

  // Every entry, so the opening balance can be derived from activity before `from`.
  const { data: entries } = useQuery({
    queryKey: ["invoice-entries", id],
    queryFn: async () =>
      (
        await supabase
          .from("ledger_entries")
          .select("id, date, kind, category, amount_cents, note, attendance_id")
          .eq("student_id", id)
          .order("date")
      ).data ?? [],
  });

  // Guardians from the intake form, plus any linked parent login accounts.
  const { data: recipients } = useQuery({
    queryKey: ["invoice-recipients", id],
    queryFn: async () => {
      const [guardians, links] = await Promise.all([
        supabase.from("student_guardians").select("full_name, email").eq("student_id", id),
        supabase.from("parent_students").select("parent_id").eq("student_id", id),
      ]);
      const emails = new Map<string, string>();
      for (const g of guardians.data ?? [])
        if (g.email) emails.set(g.email.toLowerCase(), g.full_name ?? g.email);
      const ids = (links.data ?? []).map((l) => l.parent_id);
      if (ids.length) {
        // profiles is admin-readable only; non-admins simply get fewer recipients.
        const { data: profs } = await supabase
          .from("profiles")
          .select("full_name, email")
          .in("id", ids);
        for (const p of profs ?? [])
          if (p.email) emails.set(p.email.toLowerCase(), p.full_name ?? p.email);
      }
      return [...emails.entries()].map(([email, name]) => ({ email, name }));
    },
  });

  if (!student) {
    return (
      <div className="p-8 flex items-center gap-2 text-sm text-muted-foreground">
        <Loader2 className="h-4 w-4 animate-spin" /> Loading invoice…
      </div>
    );
  }

  const all = entries ?? [];
  const signed = (e: { kind: string; amount_cents: number }) =>
    e.kind === "charge" ? e.amount_cents : -e.amount_cents;

  const opening = all.filter((e) => e.date < from).reduce((n, e) => n + signed(e), 0);
  const period = all.filter((e) => e.date >= from && e.date <= to);
  const charges = period.filter((e) => e.kind === "charge").reduce((n, e) => n + e.amount_cents, 0);
  const payments = period
    .filter((e) => e.kind === "payment")
    .reduce((n, e) => n + e.amount_cents, 0);
  const balanceDue = opening + charges - payments;

  const name = `${student.first_name} ${student.last_name}`;
  const lines = period
    .map(
      (e) =>
        `${formatDate(e.date)}  ${CATEGORY_LABEL[e.category] ?? e.category}${e.note ? ` — ${e.note}` : ""}  ${
          e.kind === "charge" ? money(e.amount_cents) : `(${money(e.amount_cents)})`
        }`,
    )
    .join("\n");

  // mailto: is the same mechanism the intake-link share uses — it opens the
  // staff member's own mail client with a prefilled draft. It cannot attach a
  // file, so the itemisation goes in the body as text.
  const mailto =
    `mailto:${(recipients ?? []).map((r) => r.email).join(",")}` +
    `?subject=${encodeURIComponent(`${SCHOOL_NAME} — invoice for ${name}`)}` +
    `&body=${encodeURIComponent(
      `Hello,\n\nHere is the tuition statement for ${name} covering ${formatDate(from)} to ${formatDate(to)}.\n\n` +
        `Balance carried forward: ${money(opening)}\n` +
        `${lines ? `${lines}\n\n` : "\n"}` +
        `Charges this period: ${money(charges)}\n` +
        `Payments this period: ${money(payments)}\n` +
        `Balance due: ${money(balanceDue)}\n\n` +
        `Please reply to this email with any questions.\n\nThank you,\n${SCHOOL_NAME}`,
    )}`;

  return (
    <div className="p-6 md:p-8 max-w-3xl">
      <div className="no-print space-y-3">
        <Link to="/ledger" className="text-sm text-muted-foreground inline-flex items-center gap-1">
          <ArrowLeft className="h-4 w-4" /> Tuition ledger
        </Link>
        <div className="bg-card border rounded-lg p-4 flex flex-wrap gap-3 items-end">
          <div>
            <Label className="text-xs">From</Label>
            <Input
              type="date"
              key={`f${from}`}
              defaultValue={from}
              onChange={(e) => setFrom(e.target.value)}
            />
          </div>
          <div>
            <Label className="text-xs">To</Label>
            <Input
              type="date"
              key={`t${to}`}
              defaultValue={to}
              onChange={(e) => setTo(e.target.value)}
            />
          </div>
          <Button
            size="sm"
            variant="outline"
            onClick={() => {
              const r = schoolYearRange();
              setFrom(r.from);
              setTo(r.to);
            }}
          >
            School year
          </Button>
          <div className="flex-1" />
          <Button size="sm" onClick={() => window.print()}>
            <Printer className="h-4 w-4 mr-1" /> Print
          </Button>
          {(recipients ?? []).length > 0 ? (
            <a href={mailto}>
              <Button size="sm" variant="outline">
                <Mail className="h-4 w-4 mr-1" /> Email to parents
              </Button>
            </a>
          ) : (
            <Button
              size="sm"
              variant="outline"
              disabled
              title="No guardian or parent email on file"
            >
              <Mail className="h-4 w-4 mr-1" /> Email to parents
            </Button>
          )}
        </div>
        {(recipients ?? []).length > 0 && (
          <p className="text-xs text-muted-foreground">
            Will draft to: {(recipients ?? []).map((r) => r.email).join(", ")}
          </p>
        )}
      </div>

      <div className="print-doc bg-card border rounded-lg p-6 mt-6 space-y-5">
        <DocHeader title="Invoice" subtitle={`${formatDate(from)} – ${formatDate(to)}`} />

        <div className="grid grid-cols-2 gap-x-8 gap-y-1 text-sm">
          {[
            ["Student", name],
            ["Grade level", student.grade_level || "—"],
            ["Class", (student.classes as { name: string } | null)?.name ?? "—"],
            [
              "Daily rate",
              student.daily_tuition_cents ? money(student.daily_tuition_cents) : "Not set",
            ],
          ].map(([k, v]) => (
            <div key={k} className="flex justify-between border-b py-1">
              <span className="text-muted-foreground">{k}</span>
              <span className="font-medium text-right">{v}</span>
            </div>
          ))}
        </div>

        <div>
          <h3 className="text-sm font-semibold uppercase tracking-wide mb-2">Account activity</h3>
          <table className="w-full text-sm">
            <thead>
              <tr className="border-b text-left">
                <th className="py-1 font-medium">Date</th>
                <th className="py-1 font-medium">Description</th>
                <th className="py-1 font-medium text-right">Charge</th>
                <th className="py-1 font-medium text-right">Payment</th>
              </tr>
            </thead>
            <tbody>
              <tr className="border-b">
                <td className="py-1 text-muted-foreground">{formatDate(from)}</td>
                <td className="py-1 text-muted-foreground">Balance carried forward</td>
                <td className="py-1 text-right">{opening !== 0 ? money(opening) : "—"}</td>
                <td className="py-1 text-right">—</td>
              </tr>
              {period.map((e) => (
                <tr key={e.id} className="border-b">
                  <td className="py-1">{formatDate(e.date)}</td>
                  <td className="py-1">
                    {CATEGORY_LABEL[e.category] ?? e.category}
                    {e.note ? <span className="text-muted-foreground"> — {e.note}</span> : null}
                  </td>
                  <td className="py-1 text-right">
                    {e.kind === "charge" ? money(e.amount_cents) : "—"}
                  </td>
                  <td className="py-1 text-right">
                    {e.kind === "payment" ? money(e.amount_cents) : "—"}
                  </td>
                </tr>
              ))}
              {period.length === 0 && (
                <tr>
                  <td colSpan={4} className="py-3 text-sm text-muted-foreground">
                    No activity in this period.
                  </td>
                </tr>
              )}
            </tbody>
            <tfoot>
              <tr>
                <td colSpan={2} className="pt-2 text-right text-muted-foreground">
                  Charges this period
                </td>
                <td className="pt-2 text-right">{money(charges)}</td>
                <td />
              </tr>
              <tr>
                <td colSpan={2} className="text-right text-muted-foreground">
                  Payments this period
                </td>
                <td />
                <td className="text-right">{money(payments)}</td>
              </tr>
              <tr className="font-semibold text-base">
                <td colSpan={2} className="pt-2 text-right">
                  Balance due
                </td>
                <td colSpan={2} className="pt-2 text-right">
                  {money(balanceDue)}
                </td>
              </tr>
            </tfoot>
          </table>
          {balanceDue < 0 && (
            <p className="text-xs text-muted-foreground mt-1">
              A negative balance is a credit on the account.
            </p>
          )}
        </div>

        <SignatureLines labels={["Received by", "Date"]} />
      </div>
    </div>
  );
}