import { createFileRoute, useNavigate, Outlet, useMatches } from "@tanstack/react-router";
import { useEffect, useMemo, useState } from "react";
import { ProtectedLayout } from "@/components/protected-layout";
import { PageContainer, PageHeader } from "@/components/app-shell";
import { Card, CardContent } from "@/components/ui/card";
import { Input } from "@/components/ui/input";
import { Badge } from "@/components/ui/badge";
import { Button } from "@/components/ui/button";
import { supabase } from "@/integrations/supabase/client";
import { Search, ArrowLeft } from "lucide-react";
import { formatCurrency } from "@/lib/format";

export const Route = createFileRoute("/invoices/new")({
  component: NewInvoiceLayout,
});

function NewInvoiceLayout() {
  // If a child route (e.g. /invoices/new/$clientId) is matched, render only it.
  const matches = useMatches();
  const hasChild = matches.some((m) => m.routeId !== "/invoices/new" && m.routeId.startsWith("/invoices/new/"));
  if (hasChild) return <Outlet />;
  return (
    <ProtectedLayout>
      <NewInvoicePickClient />
    </ProtectedLayout>
  );
}

interface ClientLite {
  id: string;
  name: string;
  unbilledTotal: number;
  unbilledTimeAmount: number;
  unbilledExpenseAmount: number;
  caseCount: number;
}

function NewInvoicePickClient() {
  const navigate = useNavigate();
  const [clients, setClients] = useState<ClientLite[]>([]);
  const [loading, setLoading] = useState(true);
  const [q, setQ] = useState("");

  useEffect(() => {
    (async () => {
      setLoading(true);
      const { data: cs } = await supabase
        .from("clients")
        .select("id, name")
        .is("archived_at", null)
        .order("name", { ascending: true });
      const clientList = cs ?? [];
      if (clientList.length === 0) {
        setClients([]);
        setLoading(false);
        return;
      }
      const { data: cases } = await supabase
        .from("cases")
        .select("id, client_id")
        .is("archived_at", null)
        .in("client_id", clientList.map((c) => c.id));
      const caseToClient = new Map<string, string>();
      const clientCaseCount = new Map<string, number>();
      for (const c of cases ?? []) {
        if (!c.client_id) continue;
        caseToClient.set(c.id, c.client_id);
        clientCaseCount.set(c.client_id, (clientCaseCount.get(c.client_id) ?? 0) + 1);
      }
      const caseIds = Array.from(caseToClient.keys());
      const tally = new Map<string, { time: number; expense: number }>();
      if (caseIds.length > 0) {
        const [{ data: time }, { data: exp }] = await Promise.all([
          supabase.from("time_entries").select("case_id, hours, hourly_rate")
            .in("case_id", caseIds).eq("billable", true).is("invoice_id", null),
          supabase.from("expenses").select("case_id, amount")
            .in("case_id", caseIds).eq("billable", true).is("invoice_id", null),
        ]);
        for (const t of time ?? []) {
          const cid = caseToClient.get(t.case_id);
          if (!cid) continue;
          const cur = tally.get(cid) ?? { time: 0, expense: 0 };
          cur.time += Number(t.hours) * Number(t.hourly_rate);
          tally.set(cid, cur);
        }
        for (const e of exp ?? []) {
          const cid = caseToClient.get(e.case_id);
          if (!cid) continue;
          const cur = tally.get(cid) ?? { time: 0, expense: 0 };
          cur.expense += Number(e.amount);
          tally.set(cid, cur);
        }
      }
      const enriched: ClientLite[] = clientList.map((c) => {
        const t = tally.get(c.id) ?? { time: 0, expense: 0 };
        return {
          id: c.id,
          name: c.name,
          unbilledTimeAmount: t.time,
          unbilledExpenseAmount: t.expense,
          unbilledTotal: t.time + t.expense,
          caseCount: clientCaseCount.get(c.id) ?? 0,
        };
      });
      enriched.sort((a, b) => {
        if ((b.unbilledTotal > 0 ? 1 : 0) !== (a.unbilledTotal > 0 ? 1 : 0)) {
          return (b.unbilledTotal > 0 ? 1 : 0) - (a.unbilledTotal > 0 ? 1 : 0);
        }
        if (b.unbilledTotal !== a.unbilledTotal) return b.unbilledTotal - a.unbilledTotal;
        return a.name.localeCompare(b.name);
      });
      setClients(enriched);
      setLoading(false);
    })();
  }, []);

  const filtered = useMemo(() => {
    if (!q) return clients;
    const s = q.toLowerCase();
    return clients.filter((c) => c.name.toLowerCase().includes(s));
  }, [clients, q]);

  return (
    <PageContainer>
      <PageHeader
        title="New invoice — choose a client"
        description="Pick a client to see their cases with unbilled time and expenses."
        actions={
          <Button variant="outline" onClick={() => navigate({ to: "/invoices" })}>
            <ArrowLeft className="h-4 w-4 mr-2" /> Back to invoices
          </Button>
        }
      />

      <Card className="border-border/60 mb-4">
        <CardContent className="p-3">
          <div className="relative">
            <Search className="absolute left-3 top-1/2 -translate-y-1/2 h-4 w-4 text-muted-foreground" />
            <Input
              autoFocus
              className="pl-9"
              placeholder="Search clients…"
              value={q}
              onChange={(e) => setQ(e.target.value)}
            />
          </div>
        </CardContent>
      </Card>

      <Card className="border-border/60">
        <CardContent className="p-0 divide-y">
          {loading && <div className="py-12 text-center text-sm text-muted-foreground">Loading clients…</div>}
          {!loading && filtered.length === 0 && (
            <div className="py-12 text-center text-sm text-muted-foreground">No matching clients.</div>
          )}
          {!loading && filtered.map((c) => (
            <button
              key={c.id}
              type="button"
              onClick={() => navigate({ to: "/invoices/new/$clientId", params: { clientId: c.id } })}
              className="w-full text-left p-4 hover:bg-muted/40 transition-colors"
            >
              <div className="flex items-center justify-between gap-3">
                <div className="min-w-0">
                  <div className="font-medium truncate">{c.name}</div>
                  <div className="text-xs text-muted-foreground mt-0.5">
                    {c.caseCount} {c.caseCount === 1 ? "case" : "cases"}
                    {c.unbilledTotal > 0 && (
                      <>
                        {" · "}
                        {formatCurrency(c.unbilledTimeAmount)} time
                        {c.unbilledExpenseAmount > 0 && <> · {formatCurrency(c.unbilledExpenseAmount)} expenses</>}
                      </>
                    )}
                  </div>
                </div>
                <div className="text-right shrink-0">
                  {c.unbilledTotal > 0 ? (
                    <Badge variant="outline" className="bg-primary/10 text-primary border-primary/30 tabular-nums">
                      {formatCurrency(c.unbilledTotal)} unbilled
                    </Badge>
                  ) : (
                    <span className="text-[11px] text-muted-foreground">No unbilled work</span>
                  )}
                </div>
              </div>
            </button>
          ))}
        </CardContent>
      </Card>
    </PageContainer>
  );
}