"use client";

import { useState, useTransition } from "react";
import { useRouter } from "next/navigation";
import Link from "next/link";
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card";
import { Button } from "@/components/ui/button";
import { Input } from "@/components/ui/input";
import { Label } from "@/components/ui/label";
import { Select } from "@/components/ui/select";
import { Combobox } from "@/components/ui/combobox";
import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table";
import { Badge } from "@/components/ui/badge";
import { Pagination } from "@/components/ui/pagination";
import {
  Dialog,
  DialogContent,
  DialogDescription,
  DialogFooter,
  DialogHeader,
  DialogTitle,
} from "@/components/ui/dialog";
import { applyMonthlyIncrease, createPricingRule, deletePricingRule, updateDefaultPrice } from "@/actions/pricing";
import { toast } from "sonner";
import { Plus, Search, Trash2, X } from "lucide-react";
import type { Customer, CustomerPricing } from "@/lib/types";
import { formatCurrency } from "@/lib/utils";

interface Props {
  rules: CustomerPricing[];
  customers: Customer[];
  customerMap: [string, Customer][];
  defaultPrice: number;
  searchQuery: string;
  page: number;
  totalPages: number;
  totalItems: number;
}

const MONTHS = [
  "January", "February", "March", "April", "May", "June",
  "July", "August", "September", "October", "November", "December",
];

export function PricingManagement({ rules, customers, customerMap, defaultPrice, searchQuery, page, totalPages, totalItems }: Props) {
  const router = useRouter();
  const customerLookup = new Map(customerMap);
  const [defaultPriceDraft, setDefaultPriceDraft] = useState(defaultPrice);
  const [open, setOpen] = useState(false);
  const [year, setYear] = useState(new Date().getFullYear());
  const [month, setMonth] = useState(new Date().getMonth() + 1);
  const [delta, setDelta] = useState(5);
  const [, startTransition] = useTransition();

  function onSaveDefault() {
    startTransition(async () => {
      const res = await updateDefaultPrice(defaultPriceDraft);
      if (res.ok) {
        toast.success("Default price updated");
        router.refresh();
      } else {
        toast.error(res.error);
      }
    });
  }

  function onApplyIncrease() {
    startTransition(async () => {
      const res = await applyMonthlyIncrease(year, month, delta);
      if (res.ok) {
        toast.success(`Applied ${delta}¢ increase to all customers for ${MONTHS[month - 1]} ${year}`);
        router.refresh();
      } else {
        toast.error(res.error);
      }
    });
  }

  function onDeleteRule(id: string) {
    if (!confirm("Delete this pricing rule?")) return;
    startTransition(async () => {
      const res = await deletePricingRule(id);
      if (res.ok) {
        toast.success("Rule deleted");
        router.refresh();
      } else {
        toast.error(res.error);
      }
    });
  }

  return (
    <div className="space-y-6">
      <div>
        <h1 className="text-2xl font-semibold tracking-tight">Pricing</h1>
        <p className="text-sm text-muted-foreground">Default price, monthly increases, and per-customer rules</p>
      </div>

      <div className="grid gap-6 lg:grid-cols-2">
        <Card>
          <CardHeader>
            <CardTitle>Default fuel price</CardTitle>
            <CardDescription>Used when no per-customer rule exists for the month</CardDescription>
          </CardHeader>
          <CardContent>
            <div className="flex items-end gap-2">
              <div className="space-y-2 flex-1">
                <Label htmlFor="default-price">Default price (R / L)</Label>
                <Input
                  id="default-price"
                  type="number"
                  step="0.01"
                  min="0"
                  value={defaultPriceDraft}
                  onChange={(e) => setDefaultPriceDraft(Number(e.target.value))}
                />
              </div>
              <Button onClick={onSaveDefault}>Save</Button>
            </div>
          </CardContent>
        </Card>

        <Card>
          <CardHeader>
            <CardTitle>Monthly bulk increase</CardTitle>
            <CardDescription>Add cents per litre to all active customers for a month</CardDescription>
          </CardHeader>
          <CardContent>
            <div className="grid grid-cols-3 gap-2">
              <div className="space-y-2">
                <Label htmlFor="year">Year</Label>
                <Input id="year" type="number" value={year} onChange={(e) => setYear(Number(e.target.value))} />
              </div>
              <div className="space-y-2">
                <Label htmlFor="month">Month</Label>
                <Select
                  id="month"
                  value={String(month)}
                  onChange={(e) => setMonth(Number(e.target.value))}
                  options={MONTHS.map((m, i) => ({ value: String(i + 1), label: m }))}
                />
              </div>
              <div className="space-y-2">
                <Label htmlFor="delta">Δ cents</Label>
                <Input id="delta" type="number" value={delta} onChange={(e) => setDelta(Number(e.target.value))} />
              </div>
            </div>
            <Button onClick={onApplyIncrease} className="mt-3 w-full">
              Apply to all customers
            </Button>
          </CardContent>
        </Card>
      </div>

      <Card>
        <CardHeader className="flex flex-row items-center justify-between">
          <div>
            <CardTitle>Per-customer pricing rules</CardTitle>
            <CardDescription>
              {searchQuery
                ? `${totalItems} match "${searchQuery}"`
                : `${totalItems} rule${totalItems !== 1 ? "s" : ""}`}
            </CardDescription>
          </div>
          <Button onClick={() => setOpen(true)} size="sm">
            <Plus className="h-4 w-4" /> Add rule
          </Button>
        </CardHeader>
        <form action="/pricing" className="flex flex-wrap items-center gap-2 px-6 pb-4">
          <div className="relative flex-1 min-w-[200px] max-w-md">
            <Search className="pointer-events-none absolute left-3 top-1/2 h-4 w-4 -translate-y-1/2 text-muted-foreground" />
            <input
              name="q"
              type="search"
              defaultValue={searchQuery}
              placeholder="Search by customer name…"
              className="h-9 w-full rounded-md border border-input bg-transparent pl-9 pr-3 py-1 text-sm outline-none focus-visible:border-ring focus-visible:ring-1 focus-visible:ring-ring"
            />
          </div>
          <Button type="submit" size="sm" variant="secondary">
            Search
          </Button>
          {searchQuery && (
            <Button asChild variant="ghost" size="sm">
              <Link href="/pricing">
                <X className="h-4 w-4" /> Clear
              </Link>
            </Button>
          )}
        </form>
        <Table>
          <TableHeader>
            <TableRow>
              <TableHead>Customer</TableHead>
              <TableHead>Year</TableHead>
              <TableHead>Month</TableHead>
              <TableHead className="text-right">Price / L</TableHead>
              <TableHead className="text-right">Special</TableHead>
              <TableHead className="w-12"></TableHead>
            </TableRow>
          </TableHeader>
          <TableBody>
            {rules.length === 0 && (
              <TableRow>
                <TableCell colSpan={6} className="text-center text-muted-foreground py-8">
                  {searchQuery
                    ? `No rules match "${searchQuery}".`
                    : "No pricing rules yet."}
                </TableCell>
              </TableRow>
            )}
            {rules.map((r) => {
              const customer = customerLookup.get(r.customer);
              return (
                <TableRow key={r.id}>
                  <TableCell className="font-medium">{customer?.name || r.customer}</TableCell>
                  <TableCell>{r.year}</TableCell>
                  <TableCell>{MONTHS[r.month - 1]}</TableCell>
                  <TableCell className="text-right">{formatCurrency(r.price_per_litre)}</TableCell>
                  <TableCell className="text-right">
                    {r.special_price != null ? <Badge variant="success">{formatCurrency(r.special_price)}</Badge> : "—"}
                  </TableCell>
                  <TableCell>
                    <Button variant="ghost" size="icon" onClick={() => onDeleteRule(r.id)}>
                      <Trash2 className="h-4 w-4" />
                    </Button>
                  </TableCell>
                </TableRow>
              );
            })}
          </TableBody>
        </Table>
        <Pagination
          page={page}
          totalPages={totalPages}
          totalItems={totalItems}
          perPage={25}
          basePath="/pricing"
          query={searchQuery ? { q: searchQuery } : undefined}
        />
      </Card>

      <NewRuleDialog open={open} onOpenChange={setOpen} customers={customers} />
    </div>
  );
}

function NewRuleDialog({ open, onOpenChange, customers }: { open: boolean; onOpenChange: (v: boolean) => void; customers: Customer[] }) {
  const router = useRouter();
  const [pending, startTransition] = useTransition();
  const [customer, setCustomer] = useState("");
  const [year, setYear] = useState(new Date().getFullYear());
  const [month, setMonth] = useState(new Date().getMonth() + 1);
  const [price, setPrice] = useState(0);
  const [special, setSpecial] = useState<number | "">("");

  function onSubmit() {
    if (!customer || !price) {
      toast.error("Customer and price are required");
      return;
    }
    const fd = new FormData();
    fd.set("customer", customer);
    fd.set("year", String(year));
    fd.set("month", String(month));
    fd.set("price_per_litre", String(price));
    if (special) fd.set("special_price", String(special));
    startTransition(async () => {
      const res = await createPricingRule(null, fd);
      if (res.ok) {
        toast.success("Rule created");
        onOpenChange(false);
        setCustomer("");
        setPrice(0);
        setSpecial("");
        router.refresh();
      } else {
        toast.error(res.error);
      }
    });
  }

  return (
    <Dialog open={open} onOpenChange={onOpenChange}>
      <DialogContent>
        <DialogHeader>
          <DialogTitle>Add pricing rule</DialogTitle>
          <DialogDescription>Set a price for a specific customer and month.</DialogDescription>
        </DialogHeader>
        <div className="space-y-3">
          <div className="space-y-2">
            <Label htmlFor="r-customer">Customer *</Label>
            <Combobox
              id="r-customer"
              value={customer}
              onChange={setCustomer}
              items={customers.map((c) => ({ value: c.id, label: c.name }))}
              placeholder="Search customers…"
              required
            />
          </div>
          <div className="grid grid-cols-2 gap-3">
            <div className="space-y-2">
              <Label htmlFor="r-year">Year *</Label>
              <Input id="r-year" type="number" value={year} onChange={(e) => setYear(Number(e.target.value))} />
            </div>
            <div className="space-y-2">
              <Label htmlFor="r-month">Month *</Label>
              <Select
                id="r-month"
                value={String(month)}
                onChange={(e) => setMonth(Number(e.target.value))}
                options={MONTHS.map((m, i) => ({ value: String(i + 1), label: m }))}
              />
            </div>
          </div>
          <div className="grid grid-cols-2 gap-3">
            <div className="space-y-2">
              <Label htmlFor="r-price">Price / L *</Label>
              <Input id="r-price" type="number" step="0.01" min="0.01" value={price || ""} onChange={(e) => setPrice(Number(e.target.value))} />
            </div>
            <div className="space-y-2">
              <Label htmlFor="r-special">Special price</Label>
              <Input id="r-special" type="number" step="0.01" min="0" value={special} onChange={(e) => setSpecial(e.target.value === "" ? "" : Number(e.target.value))} />
            </div>
          </div>
        </div>
        <DialogFooter>
          <Button variant="ghost" onClick={() => onOpenChange(false)} disabled={pending}>Cancel</Button>
          <Button onClick={onSubmit} disabled={pending}>
            {pending ? "Creating…" : "Create rule"}
          </Button>
        </DialogFooter>
      </DialogContent>
    </Dialog>
  );
}