import { useState } from "react";
import { data, type ActionFunctionArgs, type LoaderFunctionArgs } from "@remix-run/node";
import { Form, useLoaderData, useNavigation, useSearchParams } from "@remix-run/react";
import {
  Page,
  Card,
  BlockStack,
  InlineStack,
  Text,
  Button,
  Select,
  TextField,
  IndexTable,
  EmptyState,
} from "@shopify/polaris";
import { TitleBar } from "@shopify/app-bridge-react";
import { authenticate } from "../shopify.server";
import db from "../db.server";
import { getShopTier } from "../services/billing.server";
import { tierAtLeast } from "../lib/billing-plans";
import { UpsellState } from "../components/UpsellState";

const ZONE_TYPES = [
  { label: "Postal / ZIP codes", value: "postal" },
  { label: "Radius (straight-line distance)", value: "radius" },
  { label: "Driving distance (via Google Maps)", value: "driving" },
];

export const loader = async ({ request }: LoaderFunctionArgs) => {
  const { session } = await authenticate.admin(request);

  const tier = await getShopTier(session.shop);
  if (!tierAtLeast(tier, "growth")) {
    return { gated: true as const, tier };
  }

  const url = new URL(request.url);
  const locationId = url.searchParams.get("locationId");

  const locations = await db.location.findMany({
    where: { shopDomain: session.shop },
    orderBy: { createdAt: "asc" },
  });

  const activeLocationId = locationId || locations[0]?.id || null;

  const zones = activeLocationId
    ? await db.zone.findMany({
        where: { shopDomain: session.shop, locationId: activeLocationId },
        orderBy: { createdAt: "asc" },
      })
    : [];

  return { gated: false as const, locations, activeLocationId, zones };
};

export const action = async ({ request }: ActionFunctionArgs) => {
  const { session } = await authenticate.admin(request);

  const tier = await getShopTier(session.shop);
  if (!tierAtLeast(tier, "growth")) {
    return data({ errors: { name: "Delivery zones need the Growth plan or higher." } }, { status: 403 });
  }

  const formData = await request.formData();
  const intent = formData.get("intent");

  if (intent === "delete") {
    const id = String(formData.get("id") || "");
    await db.zone.deleteMany({ where: { id, shopDomain: session.shop } });
    return data({ ok: true });
  }

  const locationId = String(formData.get("locationId") || "");
  const name = String(formData.get("name") || "").trim();
  const type = String(formData.get("type") || "postal");
  const postalCodesRaw = String(formData.get("postalCodes") || "");
  const radiusKmRaw = String(formData.get("radiusKm") || "");
  const minOrdersRaw = String(formData.get("minOrders") || "");

  const errors: Record<string, string> = {};
  if (!locationId) errors.locationId = "Choose a location";
  if (!name) errors.name = "Name is required";
  if ((type === "radius" || type === "driving") && !radiusKmRaw) errors.radiusKm = "Distance is required for this zone type";
  if (Object.keys(errors).length > 0) {
    return data({ errors });
  }

  const postalCodes = postalCodesRaw
    .split(",")
    .map((code) => code.trim())
    .filter(Boolean);

  await db.zone.create({
    data: {
      shopDomain: session.shop,
      locationId,
      name,
      type,
      postalCodes: type === "postal" ? postalCodes : [],
      radiusKm: (type === "radius" || type === "driving") && radiusKmRaw ? Number(radiusKmRaw) : null,
      minOrders: minOrdersRaw ? Number(minOrdersRaw) : null,
    },
  });

  return data({ ok: true });
};

export default function ZonesIndex() {
  const loaderData = useLoaderData<typeof loader>();
  const [, setSearchParams] = useSearchParams();
  const navigation = useNavigation();
  const isSubmitting = navigation.state === "submitting";

  if (loaderData.gated) {
    return (
      <Page>
        <TitleBar title="Delivery zones" />
        <UpsellState
          requiredTier="growth"
          currentTier={loaderData.tier}
          feature="Delivery zones"
          description="Route Local Delivery orders by postal code or radius, with automatic nearest-location assignment."
        />
      </Page>
    );
  }

  const { locations, activeLocationId, zones } = loaderData;

  if (locations.length === 0) {
    return (
      <Page>
        <TitleBar title="Delivery zones" />
        <Card>
          <EmptyState
            heading="Add a location first"
            action={{ content: "Add location", url: "/app/locations/new" }}
            image="https://cdn.shopify.com/s/files/1/0757/9955/files/empty-state.svg"
          >
            <Text as="p">Delivery zones determine which addresses a location's Local Delivery covers.</Text>
          </EmptyState>
        </Card>
      </Page>
    );
  }

  return (
    <Page>
      <TitleBar title="Delivery zones" />
      <BlockStack gap="400">
        <Card>
          <Select
            label="Location"
            options={locations.map((l) => ({ label: l.name, value: l.id }))}
            value={activeLocationId ?? undefined}
            onChange={(value) => setSearchParams({ locationId: value })}
          />
        </Card>

        <Card padding="0">
          {zones.length === 0 ? (
            <div style={{ padding: 16 }}>
              <Text as="p" tone="subdued">
                No delivery zones yet for this location. Without a zone, Local Delivery is offered everywhere.
              </Text>
            </div>
          ) : (
            <IndexTable
              itemCount={zones.length}
              headings={[
                { title: "Name" },
                { title: "Type" },
                { title: "Coverage" },
                { title: "Min. orders" },
                { title: "" },
              ]}
              selectable={false}
            >
              {zones.map((zone, index) => (
                <IndexTable.Row id={zone.id} key={zone.id} position={index}>
                  <IndexTable.Cell>{zone.name}</IndexTable.Cell>
                  <IndexTable.Cell>
                    {zone.type === "postal" ? "Postal/ZIP" : zone.type === "driving" ? "Driving distance" : "Radius"}
                  </IndexTable.Cell>
                  <IndexTable.Cell>
                    {zone.type === "postal" ? zone.postalCodes.join(", ") || "—" : `${zone.radiusKm ?? "—"} km`}
                  </IndexTable.Cell>
                  <IndexTable.Cell>{zone.minOrders ?? "—"}</IndexTable.Cell>
                  <IndexTable.Cell>
                    <Form method="post">
                      <input type="hidden" name="intent" value="delete" />
                      <input type="hidden" name="id" value={zone.id} />
                      <Button submit variant="plain" tone="critical">
                        Remove
                      </Button>
                    </Form>
                  </IndexTable.Cell>
                </IndexTable.Row>
              ))}
            </IndexTable>
          )}
        </Card>

        <AddZoneForm key={activeLocationId} locationId={activeLocationId ?? ""} isSubmitting={isSubmitting} />
      </BlockStack>
    </Page>
  );
}

function AddZoneForm({ locationId, isSubmitting }: { locationId: string; isSubmitting: boolean }) {
  const [type, setType] = useState("postal");
  const [name, setName] = useState("");
  const [postalCodes, setPostalCodes] = useState("");
  const [radiusKm, setRadiusKm] = useState("");
  const [minOrders, setMinOrders] = useState("");

  return (
    <Card>
      <Form method="post">
        <input type="hidden" name="locationId" value={locationId} />
        <BlockStack gap="300">
          <Text as="h3" variant="headingSm">
            Add a delivery zone
          </Text>
          <InlineStack gap="300" wrap>
            <TextField label="Name" name="name" autoComplete="off" value={name} onChange={setName} />
            <Select label="Type" name="type" options={ZONE_TYPES} value={type} onChange={setType} />
            {type === "postal" ? (
              <TextField
                label="Postal/ZIP codes (comma-separated)"
                name="postalCodes"
                autoComplete="off"
                value={postalCodes}
                onChange={setPostalCodes}
                helpText="e.g. M5V 3A8, M4B 1B3"
              />
            ) : (
              <TextField
                label={type === "driving" ? "Max driving distance (km)" : "Radius (km)"}
                name="radiusKm"
                type="number"
                autoComplete="off"
                value={radiusKm}
                onChange={setRadiusKm}
                helpText={type === "driving" ? "Actual road distance via Google Maps, not straight-line." : undefined}
              />
            )}
            <TextField
              label="Min. orders before this zone unlocks (optional)"
              name="minOrders"
              type="number"
              autoComplete="off"
              value={minOrders}
              onChange={setMinOrders}
              helpText="Delivery-density threshold — leave blank for no minimum."
            />
          </InlineStack>
          <div>
            <Button submit variant="primary" loading={isSubmitting}>
              Add zone
            </Button>
          </div>
        </BlockStack>
      </Form>
    </Card>
  );
}