import { createFileRoute, Link, useNavigate } from "@tanstack/react-router";
import { useEffect, useState, useMemo } from "react";
import { ProtectedLayout } from "@/components/protected-layout";
import { PageContainer } from "@/components/app-shell";
import { Button } from "@/components/ui/button";
import { Card, CardContent } from "@/components/ui/card";
import { Badge } from "@/components/ui/badge";
import { Input } from "@/components/ui/input";
import { Label } from "@/components/ui/label";
import { Textarea } from "@/components/ui/textarea";
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 { useAuth } from "@/lib/auth";
import { ArrowLeft, FileDown, Plus, Trash2, Loader2, Send, Ban, CheckCircle2, DollarSign } from "lucide-react";
import { formatCurrency, formatDate, statusBadgeClass } from "@/lib/format";
import { downloadInvoicePdf, type InvoicePdfInput } from "@/lib/invoice-pdf";
import { recalcInvoiceTotals } from "@/lib/invoice-generation";
import { toast } from "sonner";

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

function InvoiceDetail() {
  const { invoiceId } = Route.useParams();
  const navigate = useNavigate();
  const { user, isAdmin } = useAuth();
  const [invoice, setInvoice] = useState<any>(null);
  const [items, setItems] = useState<any[]>([]);
  const [payments, setPayments] = useState<any[]>([]);
  const [firm, setFirm] = useState<any>(null);
  const [loading, setLoading] = useState(true);
  const [savingItem, setSavingItem] = useState(false);
  const [payOpen, setPayOpen] = useState(false);

  const load = async () => {
    setLoading(true);
    const [invRes, itemRes, payRes, firmRes] = await Promise.all([
      supabase
        .from("invoices")
        .select("*, client:clients(id, name, primary_contact_name, address_line1, address_line2, city, state, postal_code)")
        .eq("id", invoiceId)
        .maybeSingle(),
      supabase
        .from("invoice_line_items")
        .select("*, case:cases(id, case_number, title, practice_area), user:profiles(id, full_name, email)")
        .eq("invoice_id", invoiceId)
        .order("sort_order", { ascending: true }),
      supabase.from("invoice_payments").select("*").eq("invoice_id", invoiceId).order("paid_on", { ascending: false }),
      supabase.from("firm_settings").select("*").maybeSingle(),
    ]);
    setInvoice(invRes.data);
    setItems(itemRes.data ?? []);
    setPayments(payRes.data ?? []);
    setFirm(firmRes.data);
    setLoading(false);
  };

  useEffect(() => { load(); }, [invoiceId]);

  const groups = useMemo(() => {
    const map = new Map<string, { caseRow: any; items: any[]; subtotal: number }>();
    for (const it of items) {
      const key = it.case?.id ?? "_none";
      if (!map.has(key)) map.set(key, { caseRow: it.case, items: [], subtotal: 0 });
      const g = map.get(key)!;
      g.items.push(it);
      // Only billable rows contribute to the case subtotal. A line is
      // non-billable when it references a source time/expense entry but its
      // amount is zero (the generator stores it that way for transparency).
      const isNonBillable =
        Number(it.amount) === 0 && (it.time_entry_id || it.expense_id);
      if (!isNonBillable) g.subtotal += Number(it.amount);
    }
    return Array.from(map.values());
  }, [items]);

  if (loading) return <PageContainer><p className="text-muted-foreground">Loading…</p></PageContainer>;
  if (!invoice) {
    return (
      <PageContainer>
        <p className="text-muted-foreground">Invoice not found.</p>
        <Button variant="outline" className="mt-3" asChild>
          <Link to="/invoices"><ArrowLeft className="h-4 w-4 mr-2" /> All invoices</Link>
        </Button>
      </PageContainer>
    );
  }

  const canEdit = isAdmin || invoice.created_by === user?.id;
  const isDraft = invoice.status === "draft";
  const balance = Number(invoice.total) - Number(invoice.amount_paid);

  const setStatus = async (status: string) => {
    const { error } = await supabase.from("invoices").update({ status: status as any }).eq("id", invoiceId);
    if (error) toast.error(error.message);
    else { toast.success(`Marked ${status}`); load(); }
  };

  const removeItem = async (id: string) => {
    if (!confirm("Remove this line item?")) return;
    const { error } = await supabase.from("invoice_line_items").delete().eq("id", id);
    if (error) return toast.error(error.message);
    await recalcInvoiceTotals(invoiceId);
    load();
  };

  const updateItem = async (id: string, patch: any) => {
    const next: any = { ...patch };
    if (patch.quantity != null || patch.rate != null) {
      const cur = items.find((i) => i.id === id);
      const q = Number(patch.quantity ?? cur.quantity);
      const r = Number(patch.rate ?? cur.rate);
      next.amount = +(q * r).toFixed(2);
    }
    const { error } = await supabase.from("invoice_line_items").update(next).eq("id", id);
    if (error) return toast.error(error.message);
    await recalcInvoiceTotals(invoiceId);
    load();
  };

  const addManualItem = async (caseId: string | null) => {
    setSavingItem(true);
    const sort_order = items.length ? Math.max(...items.map((i) => i.sort_order)) + 1 : 0;
    const { error } = await supabase.from("invoice_line_items").insert({
      invoice_id: invoiceId,
      case_id: caseId,
      kind: "manual",
      description: "New line",
      quantity: 1,
      rate: 0,
      amount: 0,
      sort_order,
    });
    setSavingItem(false);
    if (error) return toast.error(error.message);
    await recalcInvoiceTotals(invoiceId);
    load();
  };

  const updateNotes = async (notes: string) => {
    await supabase.from("invoices").update({ notes }).eq("id", invoiceId);
  };

  const updateTaxRate = async (ratePct: string) => {
    const subtotal = Number(invoice.subtotal);
    const taxRate = Math.max(0, Number(ratePct) || 0) / 100;
    const tax = +(subtotal * taxRate).toFixed(2);
    const total = +(subtotal + tax).toFixed(2);
    await supabase.from("invoices").update({ tax, total }).eq("id", invoiceId);
    load();
  };

  const downloadPdf = async () => {
    let logoDataUrl: string | null = null;
    if (firm?.logo_storage_path) {
      const { data: signed } = await supabase.storage
        .from("firm-logos")
        .createSignedUrl(firm.logo_storage_path, 60);
      if (signed?.signedUrl) {
        try {
          const res = await fetch(signed.signedUrl);
          const blob = await res.blob();
          logoDataUrl = await new Promise<string>((resolve) => {
            const r = new FileReader();
            r.onload = () => resolve(r.result as string);
            r.readAsDataURL(blob);
          });
        } catch { /* ignore */ }
      }
    }

    const input: InvoicePdfInput = {
      firm: {
        name: firm?.company_name,
        address1: firm?.address_line1,
        address2: firm?.address_line2,
        city: firm?.city,
        state: firm?.state,
        postal: firm?.postal_code,
        email: firm?.contact_email,
        phone: firm?.contact_phone,
        website: firm?.website,
        footerNote: firm?.footer_note,
        logoDataUrl,
      },
      client: {
        name: invoice.client?.name ?? "Client",
        contact: invoice.client?.primary_contact_name,
        address1: invoice.client?.address_line1,
        address2: invoice.client?.address_line2,
        city: invoice.client?.city,
        state: invoice.client?.state,
        postal: invoice.client?.postal_code,
      },
      invoice: {
        number: invoice.invoice_number,
        issueDate: invoice.issue_date,
        dueDate: invoice.due_date,
        status: invoice.status,
        notes: invoice.notes,
      },
      groups: groups.map((g) => ({
        caseNumber: g.caseRow?.case_number ?? "—",
        caseTitle: g.caseRow?.title ?? "(unassigned)",
        practiceArea: g.caseRow?.practice_area,
        subtotal: g.subtotal,
        items: g.items.map((it) => {
          const name: string =
            it.user?.full_name || it.user?.email || "";
          const initials = name
            .trim()
            .split(/\s+/)
            .map((p: string) => p[0])
            .filter(Boolean)
            .slice(0, 3)
            .join("")
            .toUpperCase();
          const isNonBillable =
            Number(it.amount) === 0 && (it.time_entry_id || it.expense_id);
          return {
            kind: it.kind,
            description: it.description,
            work_date: it.work_date,
            quantity: Number(it.quantity),
            rate: Number(it.rate),
            amount: Number(it.amount),
            user_name: name || null,
            user_initials: initials || null,
            billable: !isNonBillable,
          };
        }),
      })),
      totals: {
        subtotal: Number(invoice.subtotal),
        tax: Number(invoice.tax),
        total: Number(invoice.total),
        paid: Number(invoice.amount_paid),
        balance,
      },
    };
    await downloadInvoicePdf(input, `${invoice.invoice_number}.pdf`);
  };

  const deleteInvoice = async () => {
    if (!confirm("Delete this draft invoice and unbill its time/expenses?")) return;
    // Unlink time/expenses
    await supabase.from("time_entries").update({ invoice_id: null }).eq("invoice_id", invoiceId);
    await supabase.from("expenses").update({ invoice_id: null }).eq("invoice_id", invoiceId);
    const { error } = await supabase.from("invoices").delete().eq("id", invoiceId);
    if (error) return toast.error(error.message);
    toast.success("Invoice deleted");
    navigate({ to: "/invoices" });
  };

  return (
    <PageContainer>
      <Button variant="ghost" size="sm" asChild className="mb-3 -ml-2">
        <Link to="/invoices"><ArrowLeft className="h-4 w-4 mr-1" /> All invoices</Link>
      </Button>

      <div className="flex flex-col lg:flex-row lg:items-end lg:justify-between gap-4 mb-6">
        <div>
          <div className="flex items-center gap-3 mb-1">
            <span className="text-xs uppercase tracking-widest text-muted-foreground">Invoice</span>
            <Badge variant="outline" className={statusBadgeClass(invoice.status)}>{invoice.status}</Badge>
          </div>
          <h1 className="font-serif text-3xl">{invoice.invoice_number}</h1>
          <p className="text-sm text-muted-foreground mt-1">
            <Link to="/clients/$clientId" params={{ clientId: invoice.client?.id }} className="hover:text-primary">
              {invoice.client?.name}
            </Link>
            {" · "}Issued {formatDate(invoice.issue_date)}
            {invoice.due_date && <> · Due {formatDate(invoice.due_date)}</>}
          </p>
        </div>
        <div className="flex flex-wrap gap-2">
          <Button variant="outline" onClick={downloadPdf}><FileDown className="h-4 w-4 mr-2" /> Download PDF</Button>
          {canEdit && isDraft && (
            <Button onClick={() => setStatus("sent")}><Send className="h-4 w-4 mr-2" /> Mark sent</Button>
          )}
          {canEdit && (invoice.status === "sent" || invoice.status === "overdue") && (
            <Button variant="outline" onClick={() => setStatus("paid")}><CheckCircle2 className="h-4 w-4 mr-2" /> Mark paid</Button>
          )}
          {canEdit && invoice.status !== "void" && invoice.status !== "paid" && (
            <Button variant="outline" onClick={() => setStatus("void")}><Ban className="h-4 w-4 mr-2" /> Void</Button>
          )}
          {canEdit && (
            <Button onClick={() => setPayOpen(true)}><DollarSign className="h-4 w-4 mr-2" /> Record payment</Button>
          )}
        </div>
      </div>

      <div className="grid lg:grid-cols-3 gap-5">
        <div className="lg:col-span-2 space-y-5">
          {groups.length === 0 && (
            <Card className="border-border/60">
              <CardContent className="p-6 text-center text-muted-foreground">No line items.</CardContent>
            </Card>
          )}

          {groups.map((g, gi) => (
            <Card key={gi} className="border-border/60 overflow-hidden">
              <CardContent className="p-0">
                <div className="px-4 py-3 bg-muted/40 border-b flex flex-wrap items-center justify-between gap-2">
                  <div>
                    <div className="font-medium">{g.caseRow?.title ?? "Unassigned"}</div>
                    <div className="text-xs text-muted-foreground">{g.caseRow?.case_number}{g.caseRow?.practice_area ? ` · ${g.caseRow.practice_area}` : ""}</div>
                  </div>
                  <div className="text-sm tabular-nums font-medium">{formatCurrency(g.subtotal)}</div>
                </div>
                <table className="w-full text-sm">
                  <thead className="text-xs uppercase tracking-wider text-muted-foreground">
                    <tr>
                      <th className="text-left px-3 py-2 font-medium w-[100px]">Date</th>
                      <th className="text-left px-3 py-2 font-medium">Description</th>
                      <th className="text-right px-3 py-2 font-medium w-[80px]">Qty</th>
                      <th className="text-right px-3 py-2 font-medium w-[100px]">Rate</th>
                      <th className="text-right px-3 py-2 font-medium w-[110px]">Amount</th>
                      {canEdit && isDraft && <th className="w-[40px]" />}
                    </tr>
                  </thead>
                  <tbody>
                    {g.items.map((it) => (
                      <tr key={it.id} className="border-t">
                        <td className="px-3 py-2 text-muted-foreground text-xs">{it.work_date ? formatDate(it.work_date) : "—"}</td>
                        <td className="px-3 py-2">
                          {canEdit && isDraft ? (
                            <Input className="h-8" defaultValue={it.description}
                              onBlur={(e) => e.target.value !== it.description && updateItem(it.id, { description: e.target.value })} />
                          ) : (
                            <div>
                              <div>{it.description}</div>
                              {it.user?.full_name && <div className="text-[11px] text-muted-foreground italic">{it.user.full_name}</div>}
                            </div>
                          )}
                        </td>
                        <td className="px-3 py-2 text-right tabular-nums">
                          {canEdit && isDraft ? (
                            <Input className="h-8 text-right tabular-nums" defaultValue={Number(it.quantity)}
                              onBlur={(e) => Number(e.target.value) !== Number(it.quantity) && updateItem(it.id, { quantity: Number(e.target.value) })} />
                          ) : Number(it.quantity).toFixed(2)}
                        </td>
                        <td className="px-3 py-2 text-right tabular-nums">
                          {canEdit && isDraft ? (
                            <Input className="h-8 text-right tabular-nums" defaultValue={Number(it.rate)}
                              onBlur={(e) => Number(e.target.value) !== Number(it.rate) && updateItem(it.id, { rate: Number(e.target.value) })} />
                          ) : formatCurrency(it.rate)}
                        </td>
                        <td className="px-3 py-2 text-right tabular-nums font-medium">{formatCurrency(it.amount)}</td>
                        {canEdit && isDraft && (
                          <td className="px-2 py-2 text-right">
                            <Button variant="ghost" size="icon" className="h-7 w-7 text-muted-foreground hover:text-destructive" onClick={() => removeItem(it.id)}>
                              <Trash2 className="h-3.5 w-3.5" />
                            </Button>
                          </td>
                        )}
                      </tr>
                    ))}
                  </tbody>
                </table>
                {canEdit && isDraft && (
                  <div className="border-t px-3 py-2 bg-muted/20">
                    <Button variant="ghost" size="sm" onClick={() => addManualItem(g.caseRow?.id ?? null)} disabled={savingItem}>
                      <Plus className="h-3.5 w-3.5 mr-1.5" /> Add line to {g.caseRow?.case_number ?? "this group"}
                    </Button>
                  </div>
                )}
              </CardContent>
            </Card>
          ))}

          {canEdit && isDraft && groups.length === 0 && (
            <Button variant="outline" onClick={() => addManualItem(null)}>
              <Plus className="h-4 w-4 mr-2" /> Add first line item
            </Button>
          )}

          <Card className="border-border/60">
            <CardContent className="p-4 space-y-2">
              <Label className="text-xs uppercase tracking-wider text-muted-foreground">Notes</Label>
              {canEdit && isDraft ? (
                <Textarea defaultValue={invoice.notes ?? ""} rows={3} placeholder="Payment terms, thank-you message…"
                  onBlur={(e) => updateNotes(e.target.value)} />
              ) : (
                <p className="text-sm whitespace-pre-wrap">{invoice.notes || <span className="text-muted-foreground italic">—</span>}</p>
              )}
            </CardContent>
          </Card>
        </div>

        <div className="space-y-4">
          <Card className="border-border/60">
            <CardContent className="p-5 space-y-2 text-sm">
              <Row label="Subtotal" value={formatCurrency(invoice.subtotal)} />
              <div className="flex justify-between items-center">
                <span className="text-muted-foreground">Tax</span>
                {canEdit && isDraft ? (
                  <div className="flex items-center gap-1">
                    <Input className="h-7 w-16 text-right tabular-nums" type="number" step="0.01"
                      defaultValue={invoice.subtotal > 0 ? ((Number(invoice.tax) / Number(invoice.subtotal)) * 100).toFixed(2) : "0"}
                      onBlur={(e) => updateTaxRate(e.target.value)} />
                    <span className="text-xs text-muted-foreground">%</span>
                  </div>
                ) : <span className="tabular-nums">{formatCurrency(invoice.tax)}</span>}
              </div>
              <div className="flex justify-between pt-2 border-t font-medium">
                <span>Total</span><span className="tabular-nums font-serif text-lg">{formatCurrency(invoice.total)}</span>
              </div>
              {Number(invoice.amount_paid) > 0 && (
                <>
                  <Row label="Paid" value={`- ${formatCurrency(invoice.amount_paid)}`} muted />
                  <div className="flex justify-between pt-2 border-t font-medium">
                    <span>Balance due</span><span className="tabular-nums font-serif text-lg text-primary">{formatCurrency(balance)}</span>
                  </div>
                </>
              )}
            </CardContent>
          </Card>

          <Card className="border-border/60">
            <CardContent className="p-5">
              <div className="flex items-center justify-between mb-2">
                <h3 className="font-serif text-sm">Payments</h3>
                {canEdit && (
                  <Button variant="outline" size="sm" onClick={() => setPayOpen(true)}>
                    <Plus className="h-3.5 w-3.5 mr-1" /> Add
                  </Button>
                )}
              </div>
              {payments.length === 0 && <p className="text-sm text-muted-foreground">No payments recorded.</p>}
              <div className="space-y-1">
                {payments.map((p) => (
                  <div key={p.id} className="flex justify-between items-baseline text-sm border-b py-1.5 last:border-0">
                    <div>
                      <div>{formatDate(p.paid_on)}</div>
                      <div className="text-xs text-muted-foreground">{p.method || "—"}{p.reference ? ` · ${p.reference}` : ""}</div>
                    </div>
                    <div className="flex items-center gap-2">
                      <span className="tabular-nums font-medium">{formatCurrency(p.amount)}</span>
                      {canEdit && (
                        <Button variant="ghost" size="icon" className="h-6 w-6 text-muted-foreground hover:text-destructive"
                          onClick={async () => {
                            if (!confirm("Delete this payment?")) return;
                            await supabase.from("invoice_payments").delete().eq("id", p.id);
                            load();
                          }}>
                          <Trash2 className="h-3 w-3" />
                        </Button>
                      )}
                    </div>
                  </div>
                ))}
              </div>
            </CardContent>
          </Card>

          {canEdit && isDraft && (
            <Button variant="outline" className="w-full text-destructive hover:text-destructive" onClick={deleteInvoice}>
              <Trash2 className="h-4 w-4 mr-2" /> Delete draft
            </Button>
          )}
        </div>
      </div>

      <RecordPaymentDialog
        open={payOpen}
        onOpenChange={setPayOpen}
        invoiceId={invoiceId}
        balance={balance}
        userId={user?.id ?? ""}
        onSaved={load}
      />
    </PageContainer>
  );
}

function Row({ label, value, muted }: { label: string; value: string; muted?: boolean }) {
  return (
    <div className="flex justify-between">
      <span className={muted ? "text-muted-foreground" : "text-muted-foreground"}>{label}</span>
      <span className={`tabular-nums ${muted ? "text-muted-foreground" : ""}`}>{value}</span>
    </div>
  );
}

function RecordPaymentDialog({ open, onOpenChange, invoiceId, balance, userId, onSaved }: {
  open: boolean; onOpenChange: (b: boolean) => void; invoiceId: string; balance: number; userId: string; onSaved: () => void;
}) {
  const [amount, setAmount] = useState(balance > 0 ? balance.toFixed(2) : "");
  const [paidOn, setPaidOn] = useState(new Date().toISOString().slice(0, 10));
  const [method, setMethod] = useState("check");
  const [reference, setReference] = useState("");
  const [notes, setNotes] = useState("");
  const [saving, setSaving] = useState(false);

  useEffect(() => { if (open) setAmount(balance > 0 ? balance.toFixed(2) : ""); }, [open, balance]);

  const save = async () => {
    const amt = Number(amount);
    if (!amt || amt <= 0) return toast.error("Enter a valid amount");
    setSaving(true);
    const { error } = await supabase.from("invoice_payments").insert({
      invoice_id: invoiceId,
      amount: amt,
      paid_on: paidOn,
      method,
      reference: reference || null,
      notes: notes || null,
      created_by: userId || null,
    });
    setSaving(false);
    if (error) return toast.error(error.message);
    toast.success("Payment recorded");
    onOpenChange(false);
    onSaved();
  };

  return (
    <Dialog open={open} onOpenChange={onOpenChange}>
      <DialogContent>
        <DialogHeader><DialogTitle>Record payment</DialogTitle></DialogHeader>
        <div className="space-y-3">
          <div className="grid grid-cols-2 gap-3">
            <div>
              <Label>Amount</Label>
              <Input type="number" step="0.01" value={amount} onChange={(e) => setAmount(e.target.value)} />
            </div>
            <div>
              <Label>Paid on</Label>
              <Input type="date" value={paidOn} onChange={(e) => setPaidOn(e.target.value)} />
            </div>
          </div>
          <div className="grid grid-cols-2 gap-3">
            <div>
              <Label>Method</Label>
              <Select value={method} onValueChange={setMethod}>
                <SelectTrigger><SelectValue /></SelectTrigger>
                <SelectContent>
                  <SelectItem value="check">Check</SelectItem>
                  <SelectItem value="ach">ACH / Wire</SelectItem>
                  <SelectItem value="card">Credit Card</SelectItem>
                  <SelectItem value="cash">Cash</SelectItem>
                  <SelectItem value="trust">Trust transfer</SelectItem>
                  <SelectItem value="other">Other</SelectItem>
                </SelectContent>
              </Select>
            </div>
            <div>
              <Label>Reference</Label>
              <Input value={reference} onChange={(e) => setReference(e.target.value)} placeholder="Check #, txn id…" />
            </div>
          </div>
          <div>
            <Label>Notes</Label>
            <Textarea rows={2} value={notes} onChange={(e) => setNotes(e.target.value)} />
          </div>
        </div>
        <DialogFooter>
          <Button variant="outline" onClick={() => onOpenChange(false)}>Cancel</Button>
          <Button onClick={save} disabled={saving}>
            {saving && <Loader2 className="h-4 w-4 mr-2 animate-spin" />}Save payment
          </Button>
        </DialogFooter>
      </DialogContent>
    </Dialog>
  );
}