import { useState } from "react";
import { data, type ActionFunctionArgs, type LoaderFunctionArgs } from "@remix-run/node";
import { Form, useLoaderData, useNavigation } 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 type { Method } from "@prisma/client";
import { authenticate } from "../shopify.server";
import db from "../db.server";
import { formatPriceLabel } from "../lib/currency";
import { getShopTier } from "../services/billing.server";
import { tierAtLeast } from "../lib/billing-plans";
import { UpsellState } from "../components/UpsellState";

const METHODS: Method[] = ["SHIPPING", "LOCAL_DELIVERY", "PICKUP"];
const KEYED_BY_OPTIONS = [
  { label: "Zone", value: "zone" },
  { label: "Distance band", value: "distance" },
];

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 [rates, zones] = await Promise.all([
    db.rate.findMany({ where: { shopDomain: session.shop }, include: { zone: true }, orderBy: { createdAt: "asc" } }),
    db.zone.findMany({ where: { shopDomain: session.shop }, include: { location: true }, orderBy: { name: "asc" } }),
  ]);

  return { gated: false as const, rates, 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 rates 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.rate.deleteMany({ where: { id, shopDomain: session.shop } });
    return data({ ok: true });
  }

  const method = formData.get("method") as Method;
  const name = String(formData.get("name") || "").trim();
  const keyedBy = String(formData.get("keyedBy") || "zone");
  const zoneId = String(formData.get("zoneId") || "") || null;
  const priceRaw = String(formData.get("price") || "");
  const minDistanceRaw = String(formData.get("minDistanceKm") || "");
  const maxDistanceRaw = String(formData.get("maxDistanceKm") || "");

  const errors: Record<string, string> = {};
  if (!name) errors.name = "Name is required";
  if (!priceRaw || Number.isNaN(Number(priceRaw))) errors.price = "Price is required";
  if (keyedBy === "zone" && !zoneId) errors.zoneId = "Choose a zone";
  if (Object.keys(errors).length > 0) {
    return data({ errors });
  }

  await db.rate.create({
    data: {
      shopDomain: session.shop,
      method,
      name,
      keyedBy,
      zoneId: keyedBy === "zone" ? zoneId : null,
      priceCents: Math.round(Number(priceRaw) * 100),
      minDistanceKm: keyedBy === "distance" && minDistanceRaw ? Number(minDistanceRaw) : null,
      maxDistanceKm: keyedBy === "distance" && maxDistanceRaw ? Number(maxDistanceRaw) : null,
    },
  });

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

export default function RatesIndex() {
  const loaderData = useLoaderData<typeof loader>();
  const navigation = useNavigation();
  const isSubmitting = navigation.state === "submitting";

  if (loaderData.gated) {
    return (
      <Page>
        <TitleBar title="Delivery rates" />
        <UpsellState
          requiredTier="growth"
          currentTier={loaderData.tier}
          feature="Delivery rates"
          description="Price Local Delivery by zone or distance band instead of relying on Shopify's own shipping rates."
        />
      </Page>
    );
  }

  const { rates, zones } = loaderData;

  if (zones.length === 0) {
    return (
      <Page>
        <TitleBar title="Delivery rates" />
        <Card>
          <EmptyState
            heading="Add a delivery zone first"
            action={{ content: "Add a zone", url: "/app/zones" }}
            image="https://cdn.shopify.com/s/files/1/0757/9955/files/empty-state.svg"
          >
            <Text as="p">Zone-keyed rates need at least one zone to attach to.</Text>
          </EmptyState>
        </Card>
      </Page>
    );
  }

  return (
    <Page>
      <TitleBar title="Delivery rates" />
      <BlockStack gap="400">
        <Card padding="0">
          {rates.length === 0 ? (
            <div style={{ padding: 16 }}>
              <Text as="p" tone="subdued">
                No rates yet. Without a rate, checkout uses Shopify's own configured shipping rates.
              </Text>
            </div>
          ) : (
            <IndexTable
              itemCount={rates.length}
              headings={[
                { title: "Name" },
                { title: "Method" },
                { title: "Keyed by" },
                { title: "Coverage" },
                { title: "Price" },
                { title: "" },
              ]}
              selectable={false}
            >
              {rates.map((rate, index) => (
                <IndexTable.Row id={rate.id} key={rate.id} position={index}>
                  <IndexTable.Cell>{rate.name}</IndexTable.Cell>
                  <IndexTable.Cell>{rate.method.replace("_", " ")}</IndexTable.Cell>
                  <IndexTable.Cell>{rate.keyedBy}</IndexTable.Cell>
                  <IndexTable.Cell>
                    {rate.keyedBy === "zone"
                      ? (rate.zone?.name ?? "—")
                      : `${rate.minDistanceKm ?? 0}–${rate.maxDistanceKm ?? "∞"} km`}
                  </IndexTable.Cell>
                  <IndexTable.Cell>{formatPriceLabel(rate.priceCents)}</IndexTable.Cell>
                  <IndexTable.Cell>
                    <Form method="post">
                      <input type="hidden" name="intent" value="delete" />
                      <input type="hidden" name="id" value={rate.id} />
                      <Button submit variant="plain" tone="critical">
                        Remove
                      </Button>
                    </Form>
                  </IndexTable.Cell>
                </IndexTable.Row>
              ))}
            </IndexTable>
          )}
        </Card>

        <AddRateForm zones={zones} isSubmitting={isSubmitting} />
      </BlockStack>
    </Page>
  );
}

function AddRateForm({
  zones,
  isSubmitting,
}: {
  zones: Array<{ id: string; name: string; location: { name: string } }>;
  isSubmitting: boolean;
}) {
  const [keyedBy, setKeyedBy] = useState("zone");
  const [name, setName] = useState("");
  const [price, setPrice] = useState("");
  const [minDistanceKm, setMinDistanceKm] = useState("");
  const [maxDistanceKm, setMaxDistanceKm] = useState("");

  return (
    <Card>
      <Form method="post">
        <BlockStack gap="300">
          <Text as="h3" variant="headingSm">
            Add a rate
          </Text>
          <InlineStack gap="300" wrap>
            <TextField label="Name" name="name" autoComplete="off" value={name} onChange={setName} />
            <Select label="Method" name="method" options={METHODS.map((m) => ({ label: m.replace("_", " "), value: m }))} />
            <Select label="Keyed by" name="keyedBy" options={KEYED_BY_OPTIONS} value={keyedBy} onChange={setKeyedBy} />
            {keyedBy === "zone" ? (
              <Select
                label="Zone"
                name="zoneId"
                options={zones.map((z) => ({ label: `${z.name} (${z.location.name})`, value: z.id }))}
              />
            ) : (
              <>
                <TextField
                  label="Min distance (km)"
                  name="minDistanceKm"
                  type="number"
                  autoComplete="off"
                  value={minDistanceKm}
                  onChange={setMinDistanceKm}
                />
                <TextField
                  label="Max distance (km)"
                  name="maxDistanceKm"
                  type="number"
                  autoComplete="off"
                  value={maxDistanceKm}
                  onChange={setMaxDistanceKm}
                />
              </>
            )}
            <TextField
              label="Price"
              name="price"
              type="number"
              autoComplete="off"
              value={price}
              onChange={setPrice}
              prefix="$"
            />
          </InlineStack>
          <div>
            <Button submit variant="primary" loading={isSubmitting}>
              Add rate
            </Button>
          </div>
        </BlockStack>
      </Form>
    </Card>
  );
}