import { createFileRoute, Link } 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 { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogFooter } from "@/components/ui/dialog";
import { supabase } from "@/integrations/supabase/client";
import { Receipt, Search, FilePlus } from "lucide-react";
import { formatCurrency, formatDate, statusBadgeClass } from "@/lib/format";
import { GenerateInvoiceDialog } from "@/components/invoices/generate-invoice-dialog";

export const Route = createFileRoute("/invoices/")({
  component: () => (
    <ProtectedLayout>
      <InvoicesIndex />
    </ProtectedLayout>
  ),
});

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

function InvoicesIndex() {
  const [invoices, setInvoices] = useState<any[]>([]);
  const [loading, setLoading] = useState(true);
  const [q, setQ] = useState("");
  const [status, setStatus] = useState<string>("all");

  // New-invoice flow: first pick a client, then open the generate dialog.
  const [pickerOpen, setPickerOpen] = useState(false);
  const [pickedClient, setPickedClient] = useState<{ id: string; name: string } | null>(null);

  useEffect(() => {
    (async () => {
      const { data } = await supabase
        .from("invoices")
        .select("*, client:clients(id, name), case:cases(id, case_number, title)")
        .order("created_at", { ascending: false });
      setInvoices(data ?? []);
      setLoading(false);
    })();
  }, []);

  const filtered = useMemo(() => {
    return invoices.filter((i) => {
      if (status !== "all" && i.status !== status) return false;
      if (!q) return true;
      const s = q.toLowerCase();
      return (
        i.invoice_number?.toLowerCase().includes(s) ||
        i.client?.name?.toLowerCase().includes(s) ||
        i.case?.case_number?.toLowerCase().includes(s)
      );
    });
  }, [invoices, q, status]);

  const totals = useMemo(() => {
    const outstanding = filtered.reduce((s, i) => s + (Number(i.total) - Number(i.amount_paid)), 0);
    const paid = filtered.reduce((s, i) => s + Number(i.amount_paid), 0);
    return { outstanding, paid, count: filtered.length };
  }, [filtered]);

  return (
    <PageContainer>
      <PageHeader
        title="Invoices"
        description="All client invoices across the firm"
        actions={
          <Button onClick={() => setPickerOpen(true)}>
            <FilePlus className="h-4 w-4 mr-2" /> New invoice
          </Button>
        }
      />

      <div className="grid sm:grid-cols-3 gap-3 mb-5">
        <Stat label="Invoices" value={totals.count.toString()} />
        <Stat label="Outstanding A/R" value={formatCurrency(totals.outstanding)} />
        <Stat label="Collected" value={formatCurrency(totals.paid)} />
      </div>

      <div className="flex flex-col sm:flex-row gap-2 mb-4">
        <div className="relative flex-1">
          <Search className="absolute left-3 top-1/2 -translate-y-1/2 h-4 w-4 text-muted-foreground" />
          <Input className="pl-9" placeholder="Search by invoice #, client, case…" value={q} onChange={(e) => setQ(e.target.value)} />
        </div>
        <Select value={status} onValueChange={setStatus}>
          <SelectTrigger className="w-[180px]"><SelectValue /></SelectTrigger>
          <SelectContent>
            <SelectItem value="all">All statuses</SelectItem>
            <SelectItem value="draft">Draft</SelectItem>
            <SelectItem value="sent">Sent</SelectItem>
            <SelectItem value="paid">Paid</SelectItem>
            <SelectItem value="overdue">Overdue</SelectItem>
            <SelectItem value="void">Void</SelectItem>
          </SelectContent>
        </Select>
      </div>

      <Card className="border-border/60 overflow-hidden">
        <CardContent className="p-0">
          <table className="w-full text-sm">
            <thead className="bg-muted/50 text-xs uppercase tracking-wider text-muted-foreground">
              <tr>
                <th className="text-left px-4 py-3 font-medium">Invoice #</th>
                <th className="text-left px-4 py-3 font-medium">Client</th>
                <th className="text-left px-4 py-3 font-medium">Issued</th>
                <th className="text-left px-4 py-3 font-medium">Due</th>
                <th className="text-left px-4 py-3 font-medium">Status</th>
                <th className="text-right px-4 py-3 font-medium">Total</th>
                <th className="text-right px-4 py-3 font-medium">Balance</th>
              </tr>
            </thead>
            <tbody>
              {loading && <tr><td colSpan={7} className="text-center py-12 text-muted-foreground">Loading…</td></tr>}
              {!loading && filtered.length === 0 && (
                <tr><td colSpan={7} className="text-center py-12 text-muted-foreground">
                  <Receipt className="h-8 w-8 mx-auto mb-2 opacity-40" />
                  No invoices yet. Click <strong>New invoice</strong> to generate one.
                </td></tr>
              )}
              {filtered.map((i) => {
                const balance = Number(i.total) - Number(i.amount_paid);
                return (
                  <tr key={i.id} className="border-t hover:bg-muted/30">
                    <td className="px-4 py-3">
                      <Link to="/invoices/$invoiceId" params={{ invoiceId: i.id }} className="font-medium hover:text-primary">
                        {i.invoice_number}
                      </Link>
                    </td>
                    <td className="px-4 py-3">
                      {i.client ? (
                        <Link to="/clients/$clientId" params={{ clientId: i.client.id }} className="hover:text-primary">
                          {i.client.name}
                        </Link>
                      ) : "—"}
                    </td>
                    <td className="px-4 py-3 text-muted-foreground">{formatDate(i.issue_date)}</td>
                    <td className="px-4 py-3 text-muted-foreground">{formatDate(i.due_date)}</td>
                    <td className="px-4 py-3"><Badge variant="outline" className={statusBadgeClass(i.status)}>{i.status}</Badge></td>
                    <td className="px-4 py-3 text-right tabular-nums">{formatCurrency(i.total)}</td>
                    <td className="px-4 py-3 text-right tabular-nums font-medium">{formatCurrency(balance)}</td>
                  </tr>
                );
              })}
            </tbody>
          </table>
        </CardContent>
      </Card>

      <ClientPickerDialog
        open={pickerOpen}
        onOpenChange={setPickerOpen}
        onPick={(c) => {
          setPickerOpen(false);
          setPickedClient(c);
        }}
      />

      {pickedClient && (
        <GenerateInvoiceDialog
          open={!!pickedClient}
          onOpenChange={(b) => { if (!b) setPickedClient(null); }}
          clientId={pickedClient.id}
          clientName={pickedClient.name}
        />
      )}
    </PageContainer>
  );
}

function Stat({ label, value }: { label: string; value: string }) {
  return (
    <Card className="border-border/60">
      <CardContent className="p-4">
        <div className="text-[10px] uppercase tracking-wider text-muted-foreground">{label}</div>
        <div className="font-serif text-2xl mt-1">{value}</div>
      </CardContent>
    </Card>
  );
}

function ClientPickerDialog({
  open,
  onOpenChange,
  onPick,
}: {
  open: boolean;
  onOpenChange: (b: boolean) => void;
  onPick: (c: { id: string; name: string }) => void;
}) {
  const [clients, setClients] = useState<ClientLite[]>([]);
  const [loading, setLoading] = useState(false);
  const [q, setQ] = useState("");

  useEffect(() => {
    if (!open) return;
    (async () => {
      setLoading(true);
      // Pull every active client and their cases, then aggregate unbilled time/expenses.
      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,
        };
      });
      // Sort: clients with unbilled work first, then alphabetical.
      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);
    })();
  }, [open]);

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

  return (
    <Dialog open={open} onOpenChange={onOpenChange}>
      <DialogContent className="max-w-xl">
        <DialogHeader>
          <DialogTitle>New invoice — choose a client</DialogTitle>
        </DialogHeader>
        <div className="space-y-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>
          <div className="border rounded-md divide-y max-h-[400px] overflow-auto">
            {loading && <div className="py-8 text-center text-sm text-muted-foreground">Loading clients…</div>}
            {!loading && filtered.length === 0 && (
              <div className="py-8 text-center text-sm text-muted-foreground">No matching clients.</div>
            )}
            {!loading && filtered.map((c) => (
              <button
                key={c.id}
                type="button"
                onClick={() => onPick({ id: c.id, name: c.name })}
                className="w-full text-left p-3 hover:bg-muted/40 transition-colors"
              >
                <div className="flex items-center justify-between gap-2">
                  <div className="min-w-0">
                    <div className="font-medium text-sm truncate">{c.name}</div>
                    <div className="text-xs text-muted-foreground">
                      {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">
                    {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>
            ))}
          </div>
          <p className="text-[11px] text-muted-foreground">
            Pick a client to see a checklist of their cases and a summary of unbilled time and expenses on each.
          </p>
        </div>
        <DialogFooter>
          <Button variant="outline" onClick={() => onOpenChange(false)}>Cancel</Button>
        </DialogFooter>
      </DialogContent>
    </Dialog>
  );
}