import { useState, useEffect } from "react";
import { supabase } from "@/integrations/supabase/client";
import { useToast } from "@/hooks/use-toast";
import { FileText, Plus, Search, MoreHorizontal, Edit, Trash2, CheckCircle, XCircle, DollarSign, Download, Loader2 } from "lucide-react";
import RecordImportButton from "@/components/RecordImportButton";
import QuickAddVendorDialog from "@/components/vendors/QuickAddVendorDialog";
import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import { Card, CardContent } from "@/components/ui/card";
import { Badge } from "@/components/ui/badge";
import { Dialog, DialogContent, DialogHeader, DialogTitle, DialogFooter } from "@/components/ui/dialog";
import { Label } from "@/components/ui/label";
import { Textarea } from "@/components/ui/textarea";
import { Select, SelectContent, SelectItem, SelectTrigger, SelectValue } from "@/components/ui/select";
import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table";
import { DropdownMenu, DropdownMenuContent, DropdownMenuItem, DropdownMenuTrigger } from "@/components/ui/dropdown-menu";
import { Tabs, TabsList, TabsTrigger } from "@/components/ui/tabs";

const statusColors: Record<string, string> = {
  draft: "bg-muted text-muted-foreground",
  pending_approval: "bg-amber-100 text-amber-700",
  approved: "bg-blue-100 text-blue-700",
  rejected: "bg-red-100 text-red-700",
  paid: "bg-emerald-100 text-emerald-700",
  voided: "bg-gray-100 text-gray-500",
  partial: "bg-purple-100 text-purple-700",
};

export default function BillsPage() {
  const { toast } = useToast();
  const [bills, setBills] = useState<any[]>([]);
  const [vendors, setVendors] = useState<any[]>([]);
  const [accounts, setAccounts] = useState<any[]>([]);
  const [associations, setAssociations] = useState<any[]>([]);
  const [loading, setLoading] = useState(true);
  const [search, setSearch] = useState("");
  const [statusFilter, setStatusFilter] = useState("all");
  const [associationFilter, setAssociationFilter] = useState<string>("all");
  const [paidTab, setPaidTab] = useState<"unpaid" | "paid" | "all">("unpaid");
  const [dialogOpen, setDialogOpen] = useState(false);
  const [editing, setEditing] = useState<any>(null);
  const [buildiumOpen, setBuildiumOpen] = useState(false);
  const [buildiumAssoc, setBuildiumAssoc] = useState<string>("all");
  const [buildiumFrom, setBuildiumFrom] = useState<string>("");
  const [buildiumTo, setBuildiumTo] = useState<string>("");
  const [buildiumImporting, setBuildiumImporting] = useState(false);
  const [quickVendorOpen, setQuickVendorOpen] = useState(false);
  const [form, setForm] = useState({
    vendor_id: "", invoice_number: "", bill_date: new Date().toISOString().split("T")[0],
    due_date: "", amount: "", expense_account_id: "", description: "", notes: "", association_id: ""
  });

  const importFromBuildium = async () => {
    setBuildiumImporting(true);
    try {
      const { data, error } = await supabase.functions.invoke("buildium-sync", {
        body: {
          syncType: "bills",
          selectedAssociationIds: buildiumAssoc === "all" ? [] : [buildiumAssoc],
          dateFrom: buildiumFrom || undefined,
          dateTo: buildiumTo || undefined,
        },
      });
      if (error) throw error;
      const r = data?.results?.bills || {};
      toast({
        title: "Buildium import complete",
        description: `Fetched ${r.fetched || 0} • Created ${r.created || 0} • Updated ${r.updated || 0} • Linked duplicates ${r.linked_duplicates || 0} • Vendors created ${r.vendors_created || 0}`,
      });
      setBuildiumOpen(false);
      fetchData();
    } catch (err: any) {
      toast({ variant: "destructive", title: "Import failed", description: err?.message || String(err) });
    } finally {
      setBuildiumImporting(false);
    }
  };

  const fetchData = async () => {
    setLoading(true);
    // Paginate bills (Supabase caps default queries at 1,000 rows)
    const PAGE = 1000;
    const allBills: any[] = [];
    for (let from = 0; ; from += PAGE) {
      const { data, error } = await supabase
        .from("bills")
        .select("*, vendors(name), chart_of_accounts(account_name, account_number)")
        .order("bill_date", { ascending: false })
        .range(from, from + PAGE - 1);
      if (error) break;
      allBills.push(...(data || []));
      if (!data || data.length < PAGE) break;
    }
    const [vRes, assocRes] = await Promise.all([
      supabase.from("vendors").select("id, name, association_id, association_ids").eq("is_active", true).order("name"),
      supabase.from("associations").select("id, name, zoho_organization_id").eq("status", "active").order("name"),
    ]);
    setBills(allBills);
    setVendors(vRes.data || []);
    setAssociations(assocRes.data || []);
    setLoading(false);
  };

  useEffect(() => { fetchData(); }, []);

  // Re-fetch the chart of accounts whenever the selected association changes,
  // scoped to that association's accounting system (zoho vs buildium).
  useEffect(() => {
    if (!form.association_id) { setAccounts([]); return; }
    const assoc = associations.find(a => a.id === form.association_id);
    const system = assoc?.zoho_organization_id ? "zoho" : "buildium";
    supabase.from("chart_of_accounts")
      .select("id, account_name, account_number, account_type")
      .eq("is_active", true)
      .eq("accounting_system", system)
      .order("account_number")
      .then(({ data }) => setAccounts(data || []));
  }, [form.association_id, associations]);


  const filtered = bills.filter(b => {
    // Tabs split: paid vs unpaid (everything not paid except voided counts as unpaid)
    if (paidTab === "paid" && b.status !== "paid") return false;
    if (paidTab === "unpaid" && (b.status === "paid" || b.status === "voided")) return false;
    if (statusFilter !== "all" && b.status !== statusFilter) return false;
    if (associationFilter !== "all" && b.association_id !== associationFilter) return false;
    if (search) {
      const q = search.toLowerCase();
      return (b.vendors?.name || "").toLowerCase().includes(q) || (b.invoice_number || "").toLowerCase().includes(q) || (b.description || "").toLowerCase().includes(q);
    }
    return true;
  });

  const tabCounts = bills.reduce((acc, b) => {
    if (b.status === "paid") acc.paid++;
    else if (b.status !== "voided") acc.unpaid++;
    acc.all++;
    return acc;
  }, { unpaid: 0, paid: 0, all: 0 });

  const totals = bills.reduce((acc, b) => {
    acc.total += Number(b.amount);
    if (b.status === "paid") acc.paid += Number(b.amount);
    if (["draft", "pending_approval", "approved"].includes(b.status)) acc.unpaid += Number(b.amount) - Number(b.amount_paid);
    return acc;
  }, { total: 0, paid: 0, unpaid: 0 });

  const openNew = () => {
    setEditing(null);
    setForm({
      vendor_id: "", invoice_number: "", bill_date: new Date().toISOString().split("T")[0],
      due_date: "", amount: "", expense_account_id: "", description: "", notes: "",
      association_id: associations[0]?.id || ""
    });
    setDialogOpen(true);
  };

  const openEdit = (b: any) => {
    setEditing(b);
    setForm({
      vendor_id: b.vendor_id || "", invoice_number: b.invoice_number || "",
      bill_date: b.bill_date, due_date: b.due_date || "", amount: b.amount?.toString() || "",
      expense_account_id: b.expense_account_id || "", description: b.description || "",
      notes: b.notes || "", association_id: b.association_id
    });
    setDialogOpen(true);
  };

  const handleSave = async () => {
    if (!form.amount || !form.association_id) { toast({ variant: "destructive", title: "Amount and association are required" }); return; }
    const payload = {
      ...form, amount: parseFloat(form.amount) || 0,
      vendor_id: form.vendor_id || null, expense_account_id: form.expense_account_id || null,
      due_date: form.due_date || null
    };
    if (editing) {
      await supabase.from("bills").update(payload).eq("id", editing.id);
      toast({ title: "Bill updated" });
    } else {
      await supabase.from("bills").insert(payload).select("id").single();
      toast({ title: "Bill created" });
    }
    setDialogOpen(false);
    fetchData();
  };

  const updateStatus = async (id: string, status: string) => {
    // Look up the current bill so we can void/clear the linked check when reverting to unpaid
    const current = bills.find((b) => b.id === id);
    const wasPaid = current?.status === "paid";
    const revertingToUnpaid = wasPaid && (status === "approved" || status === "pending_approval" || status === "draft");

    const updates: any = { status };
    if (status === "approved") updates.approved_date = new Date().toISOString().split("T")[0];
    if (status === "paid") updates.paid_date = new Date().toISOString().split("T")[0];
    // Reverting to unpaid clears paid date, payment amount, and the linked check reference
    if (status === "approved" || status === "pending_approval" || status === "draft") {
      updates.paid_date = null;
      updates.amount_paid = 0;
      updates.payment_method = null;
      updates.check_id = null;
    }

    if (revertingToUnpaid && current?.check_id) {
      // Void the linked check
      await supabase
        .from("checks")
        .update({ status: "voided", printed: false })
        .eq("id", current.check_id);
      // Remove the matching bank ledger entry (vendor ledger) created when the check was issued
      await supabase
        .from("bank_transactions")
        .delete()
        .eq("related_entity_type", "check")
        .eq("related_entity_id", current.check_id);
    }

    await supabase.from("bills").update(updates).eq("id", id);
    toast({ title: `Bill ${status.replace("_", " ")}` });
    fetchData();
  };

  const handleDelete = async (id: string) => {
    await supabase.from("bills").delete().eq("id", id);
    toast({ title: "Bill deleted" });
    fetchData();
  };

  return (
    <div className="space-y-6">
      <div className="flex flex-col sm:flex-row sm:items-center sm:justify-between gap-4">
        <div>
          <h1 className="text-2xl font-bold text-foreground flex items-center gap-2"><FileText className="h-6 w-6 text-primary" /> Bills</h1>
          <p className="text-sm text-muted-foreground mt-1">Manage accounts payable and vendor bills.</p>
        </div>
        <div className="flex gap-2">
          <RecordImportButton
            title="Import Bills"
            description="Upload a CSV or Excel file with bill records."
            expectedColumns={[
              { key: "vendor_name", label: "Vendor Name", required: true },
              { key: "invoice_number", label: "Invoice Number" },
              { key: "amount", label: "Amount", required: true },
              { key: "bill_date", label: "Bill Date" },
              { key: "due_date", label: "Due Date" },
              { key: "description", label: "Description" },
            ]}
            onImport={async (rows) => {
              const assocId = associations[0]?.id;
              if (!assocId) throw new Error("Create an association first");
              const vendorMap = new Map(vendors.map(v => [v.name.toLowerCase(), v.id]));
              const payload = rows.map(r => ({
                vendor_id: vendorMap.get((r.vendor_name || "").toLowerCase()) || null,
                invoice_number: r.invoice_number || null,
                amount: parseFloat(r.amount) || 0,
                bill_date: r.bill_date || new Date().toISOString().split("T")[0],
                due_date: r.due_date || null,
                description: r.description || null,
                association_id: assocId,
              }));
              const { error } = await supabase.from("bills").insert(payload);
              if (error) throw error;
              toast({ title: `Imported ${rows.length} bills` });
              fetchData();
            }}
            templateFileName="bills_template.xlsx"
          />
          <Button variant="outline" className="gap-2" onClick={() => setBuildiumOpen(true)}>
            <Download className="h-4 w-4" /> Import from Buildium
          </Button>
          <Button className="gap-2" onClick={openNew}><Plus className="h-4 w-4" /> New Bill</Button>
        </div>
      </div>

      <div className="grid gap-4 md:grid-cols-3">
        <Card><CardContent className="pt-6"><p className="text-sm text-muted-foreground">Total Bills</p><p className="text-2xl font-bold font-mono">${totals.total.toLocaleString("en-US", { minimumFractionDigits: 2 })}</p></CardContent></Card>
        <Card><CardContent className="pt-6"><p className="text-sm text-muted-foreground">Paid</p><p className="text-2xl font-bold font-mono text-emerald-600">${totals.paid.toLocaleString("en-US", { minimumFractionDigits: 2 })}</p></CardContent></Card>
        <Card><CardContent className="pt-6"><p className="text-sm text-muted-foreground">Outstanding</p><p className="text-2xl font-bold font-mono text-amber-600">${totals.unpaid.toLocaleString("en-US", { minimumFractionDigits: 2 })}</p></CardContent></Card>
      </div>

      <Tabs value={paidTab} onValueChange={(v) => setPaidTab(v as "unpaid" | "paid" | "all")}>
        <TabsList>
          <TabsTrigger value="unpaid">Unpaid ({tabCounts.unpaid})</TabsTrigger>
          <TabsTrigger value="paid">Paid ({tabCounts.paid})</TabsTrigger>
          <TabsTrigger value="all">All ({tabCounts.all})</TabsTrigger>
        </TabsList>
      </Tabs>

      <div className="flex gap-2 flex-wrap">
        <div className="relative flex-1 max-w-md">
          <Search className="absolute left-3 top-1/2 -translate-y-1/2 h-4 w-4 text-muted-foreground" />
          <Input placeholder="Search bills..." className="pl-10" value={search} onChange={(e) => setSearch(e.target.value)} />
        </div>
        <Select value={statusFilter} onValueChange={setStatusFilter}>
          <SelectTrigger className="w-44"><SelectValue placeholder="All Statuses" /></SelectTrigger>
          <SelectContent>
            <SelectItem value="all">All Statuses</SelectItem>
            <SelectItem value="draft">Draft</SelectItem>
            <SelectItem value="pending_approval">Pending Approval</SelectItem>
            <SelectItem value="approved">Approved</SelectItem>
            <SelectItem value="paid">Paid</SelectItem>
            <SelectItem value="voided">Voided</SelectItem>
          </SelectContent>
        </Select>
        <Select value={associationFilter} onValueChange={setAssociationFilter}>
          <SelectTrigger className="w-64"><SelectValue placeholder="All Clients" /></SelectTrigger>
          <SelectContent>
            <SelectItem value="all">All Clients</SelectItem>
            {associations.map(a => <SelectItem key={a.id} value={a.id}>{a.name}</SelectItem>)}
          </SelectContent>
        </Select>
      </div>

      {loading ? (
        <div className="flex justify-center py-12"><div className="h-8 w-8 animate-spin rounded-full border-4 border-primary border-t-transparent" /></div>
      ) : filtered.length === 0 ? (
        <Card><CardContent className="py-12 text-center text-muted-foreground">No bills found.</CardContent></Card>
      ) : (
        <Card>
          <Table>
            <TableHeader>
              <TableRow>
                <TableHead>Vendor</TableHead>
                <TableHead>Invoice #</TableHead>
                <TableHead>Bill Date</TableHead>
                <TableHead>Due Date</TableHead>
                <TableHead>Expense Account</TableHead>
                <TableHead className="text-right">Amount</TableHead>
                <TableHead>Status</TableHead>
                <TableHead className="w-12" />
              </TableRow>
            </TableHeader>
            <TableBody>
              {filtered.map((b) => (
                <TableRow key={b.id}>
                  <TableCell className="font-medium">{b.vendors?.name || "—"}</TableCell>
                  <TableCell>{b.invoice_number || "—"}</TableCell>
                  <TableCell>{b.bill_date}</TableCell>
                  <TableCell>{b.due_date || "—"}</TableCell>
                  <TableCell className="text-sm">{b.chart_of_accounts ? `${b.chart_of_accounts.account_number} - ${b.chart_of_accounts.account_name}` : "—"}</TableCell>
                  <TableCell className="text-right font-mono font-medium">${Number(b.amount).toLocaleString("en-US", { minimumFractionDigits: 2 })}</TableCell>
                  <TableCell><Badge variant="outline" className={statusColors[b.status] || ""}>{b.status.replace("_", " ")}</Badge></TableCell>
                  <TableCell>
                    <DropdownMenu>
                      <DropdownMenuTrigger asChild><Button variant="ghost" size="icon" className="h-8 w-8"><MoreHorizontal className="h-4 w-4" /></Button></DropdownMenuTrigger>
                      <DropdownMenuContent align="end">
                        <DropdownMenuItem onClick={() => openEdit(b)}><Edit className="h-4 w-4 mr-2" /> Edit</DropdownMenuItem>
                        {b.status === "draft" && <DropdownMenuItem onClick={() => updateStatus(b.id, "pending_approval")}><CheckCircle className="h-4 w-4 mr-2" /> Submit for Approval</DropdownMenuItem>}
                        {b.status === "pending_approval" && (
                          <>
                            <DropdownMenuItem onClick={() => updateStatus(b.id, "approved")}><CheckCircle className="h-4 w-4 mr-2" /> Approve</DropdownMenuItem>
                            <DropdownMenuItem onClick={() => updateStatus(b.id, "rejected")}><XCircle className="h-4 w-4 mr-2" /> Reject</DropdownMenuItem>
                          </>
                        )}
                        {b.status === "approved" && <DropdownMenuItem onClick={() => updateStatus(b.id, "paid")}><DollarSign className="h-4 w-4 mr-2" /> Mark Paid</DropdownMenuItem>}
                        {b.status === "paid" && <DropdownMenuItem onClick={() => updateStatus(b.id, "approved")}><XCircle className="h-4 w-4 mr-2" /> Mark Unpaid</DropdownMenuItem>}
                        {b.status !== "voided" && <DropdownMenuItem onClick={() => updateStatus(b.id, "voided")}><XCircle className="h-4 w-4 mr-2" /> Void</DropdownMenuItem>}
                        <DropdownMenuItem className="text-destructive" onClick={() => handleDelete(b.id)}><Trash2 className="h-4 w-4 mr-2" /> Delete</DropdownMenuItem>
                      </DropdownMenuContent>
                    </DropdownMenu>
                  </TableCell>
                </TableRow>
              ))}
            </TableBody>
          </Table>
        </Card>
      )}

      <Dialog open={dialogOpen} onOpenChange={setDialogOpen}>
        <DialogContent className="max-w-lg">
          <DialogHeader><DialogTitle>{editing ? "Edit" : "New"} Bill</DialogTitle></DialogHeader>
          <div className="space-y-4">
            <div>
              <Label>Association</Label>
              <Select value={form.association_id} onValueChange={(v) => setForm({ ...form, association_id: v })}>
                <SelectTrigger><SelectValue placeholder="Select" /></SelectTrigger>
                <SelectContent>{associations.map(a => <SelectItem key={a.id} value={a.id}>{a.name}</SelectItem>)}</SelectContent>
              </Select>
            </div>
            <div className="grid grid-cols-2 gap-4">
              <div>
                <div className="flex items-center justify-between">
                  <Label>Vendor</Label>
                  <Button type="button" variant="link" size="sm" className="h-auto p-0 text-xs" onClick={() => setQuickVendorOpen(true)}>
                    <Plus className="h-3 w-3 mr-1" />Add new
                  </Button>
                </div>
                <Select value={form.vendor_id} onValueChange={(v) => setForm({ ...form, vendor_id: v })}>
                  <SelectTrigger><SelectValue placeholder="Select vendor" /></SelectTrigger>
                  <SelectContent>{vendors.filter(v => !form.association_id || v.association_id === form.association_id || (Array.isArray(v.association_ids) && v.association_ids.includes(form.association_id))).map(v => <SelectItem key={v.id} value={v.id}>{v.name}</SelectItem>)}</SelectContent>
                </Select>
              </div>
              <div><Label>Invoice #</Label><Input value={form.invoice_number} onChange={(e) => setForm({ ...form, invoice_number: e.target.value })} /></div>
            </div>
            <div className="grid grid-cols-3 gap-4">
              <div><Label>Bill Date</Label><Input type="date" value={form.bill_date} onChange={(e) => setForm({ ...form, bill_date: e.target.value })} /></div>
              <div><Label>Due Date</Label><Input type="date" value={form.due_date} onChange={(e) => setForm({ ...form, due_date: e.target.value })} /></div>
              <div><Label>Amount</Label><Input type="number" value={form.amount} onChange={(e) => setForm({ ...form, amount: e.target.value })} /></div>
            </div>
            <div>
              <Label>Expense Account</Label>
              <Select value={form.expense_account_id} onValueChange={(v) => setForm({ ...form, expense_account_id: v })}>
                <SelectTrigger><SelectValue placeholder="Select account" /></SelectTrigger>
                <SelectContent>{accounts.map(a => <SelectItem key={a.id} value={a.id}>{a.account_number} - {a.account_name}</SelectItem>)}</SelectContent>
              </Select>
            </div>
            <div><Label>Description</Label><Textarea value={form.description} onChange={(e) => setForm({ ...form, description: e.target.value })} rows={2} /></div>
          </div>
          <DialogFooter><Button onClick={handleSave}>{editing ? "Update" : "Create Bill"}</Button></DialogFooter>
        </DialogContent>
      </Dialog>

      <Dialog open={buildiumOpen} onOpenChange={setBuildiumOpen}>
        <DialogContent className="max-w-md">
          <DialogHeader>
            <DialogTitle>Import Bills from Buildium</DialogTitle>
          </DialogHeader>
          <div className="space-y-4">
            <p className="text-sm text-muted-foreground">
              Pull bills (and missing vendors) from Buildium. Existing bills are matched by Buildium ID and updated. Likely duplicates (same vendor + amount + invoice # or bill date) are linked instead of re-created.
            </p>
            <div>
              <Label>Association</Label>
              <Select value={buildiumAssoc} onValueChange={setBuildiumAssoc}>
                <SelectTrigger><SelectValue /></SelectTrigger>
                <SelectContent>
                  <SelectItem value="all">All Associations</SelectItem>
                  {associations.map((a) => <SelectItem key={a.id} value={a.id}>{a.name}</SelectItem>)}
                </SelectContent>
              </Select>
            </div>
            <div className="grid grid-cols-2 gap-4">
              <div>
                <Label>Due Date From</Label>
                <Input type="date" value={buildiumFrom} onChange={(e) => setBuildiumFrom(e.target.value)} />
              </div>
              <div>
                <Label>Due Date To</Label>
                <Input type="date" value={buildiumTo} onChange={(e) => setBuildiumTo(e.target.value)} />
              </div>
            </div>
          </div>
          <DialogFooter>
            <Button variant="outline" onClick={() => setBuildiumOpen(false)} disabled={buildiumImporting}>Cancel</Button>
            <Button onClick={importFromBuildium} disabled={buildiumImporting} className="gap-2">
              {buildiumImporting ? <Loader2 className="h-4 w-4 animate-spin" /> : <Download className="h-4 w-4" />}
              Import
            </Button>
          </DialogFooter>
        </DialogContent>
      </Dialog>

      <QuickAddVendorDialog
        open={quickVendorOpen}
        onOpenChange={setQuickVendorOpen}
        associationId={form.association_id || null}
        onCreated={(v) => {
          setVendors((prev) => [...prev, v].sort((a: any, b: any) => a.name.localeCompare(b.name)));
          setForm((f) => ({ ...f, vendor_id: v.id, association_id: f.association_id || v.association_id }));
        }}
      />
    </div>
  );
}