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, ChoiceList, IndexTable } 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 { getShopTier } from "../services/billing.server";
import { tierAtLeast } from "../lib/billing-plans";
import { UpsellState } from "../components/UpsellState";

// Product/collection/vendor/type/tag-scoped delivery rules (PRODUCT_STRATEGY.md
// §2 — previously unimplemented; see product-rules.server.ts). Tier-gated at
// Growth, same as Zones/Rates, since scoping rules is an "advanced operator"
// feature, not core parity every merchant needs on day one.

const SCOPE_TYPES = [
  { label: "Product", value: "product" },
  { label: "Collection", value: "collection" },
  { label: "Vendor", value: "vendor" },
  { label: "Product type", value: "type" },
  { label: "Tag", value: "tag" },
];

const METHOD_OPTIONS: Array<{ label: string; value: Method }> = [
  { label: "Shipping", value: "SHIPPING" },
  { label: "Local delivery", value: "LOCAL_DELIVERY" },
  { label: "Pickup", value: "PICKUP" },
];

const SCOPE_LABELS: Record<string, string> = {
  product: "Product ID",
  collection: "Collection ID",
  vendor: "Vendor",
  type: "Product type",
  tag: "Tag",
};

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 [rules, locations] = await Promise.all([
    db.productRule.findMany({ where: { shopDomain: session.shop }, orderBy: { createdAt: "asc" } }),
    db.location.findMany({ where: { shopDomain: session.shop }, orderBy: { createdAt: "asc" } }),
  ]);

  return { gated: false as const, rules, locations };
};

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: { scopeValue: "Product rules 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.productRule.deleteMany({ where: { id, shopDomain: session.shop } });
    return data({ ok: true });
  }

  const scopeType = String(formData.get("scopeType") || "product");
  const scopeValue = String(formData.get("scopeValue") || "").trim();
  const allowedMethods = formData.getAll("allowedMethods").map(String) as Method[];
  const allowedLocationIds = formData.getAll("allowedLocationIds").map(String);
  const leadTimeMinRaw = String(formData.get("leadTimeMin") || "");

  const errors: Record<string, string> = {};
  if (!scopeValue) errors.scopeValue = "This field is required";
  if (Object.keys(errors).length > 0) {
    return data({ errors });
  }

  await db.productRule.create({
    data: {
      shopDomain: session.shop,
      scopeType,
      scopeValue,
      allowedMethods,
      allowedLocationIds,
      leadTimeMin: leadTimeMinRaw ? Number(leadTimeMinRaw) : null,
    },
  });

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

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

  if (loaderData.gated) {
    return (
      <Page>
        <TitleBar title="Product rules" />
        <UpsellState
          requiredTier="growth"
          currentTier={loaderData.tier}
          feature="Product rules"
          description="Scope prep time, allowed methods, and allowed locations to specific products, collections, vendors, types, or tags."
        />
      </Page>
    );
  }

  const { rules, locations } = loaderData;
  const locationNameById = new Map(locations.map((l) => [l.id, l.name]));

  return (
    <Page>
      <TitleBar title="Product rules" />
      <BlockStack gap="400">
        <Card padding="0">
          {rules.length === 0 ? (
            <div style={{ padding: 16 }}>
              <Text as="p" tone="subdued">
                No product rules yet. Without one, every product uses the same lead time and is available via any
                method/location your slots allow.
              </Text>
            </div>
          ) : (
            <IndexTable
              itemCount={rules.length}
              headings={[
                { title: "Scope" },
                { title: "Extra lead time" },
                { title: "Allowed methods" },
                { title: "Allowed locations" },
                { title: "" },
              ]}
              selectable={false}
            >
              {rules.map((rule, index) => (
                <IndexTable.Row id={rule.id} key={rule.id} position={index}>
                  <IndexTable.Cell>
                    {SCOPE_LABELS[rule.scopeType] ?? rule.scopeType}: {rule.scopeValue}
                  </IndexTable.Cell>
                  <IndexTable.Cell>{rule.leadTimeMin ? `${rule.leadTimeMin} min` : "—"}</IndexTable.Cell>
                  <IndexTable.Cell>{rule.allowedMethods.length > 0 ? rule.allowedMethods.join(", ") : "Any"}</IndexTable.Cell>
                  <IndexTable.Cell>
                    {rule.allowedLocationIds.length > 0
                      ? rule.allowedLocationIds.map((id) => locationNameById.get(id) ?? id).join(", ")
                      : "Any"}
                  </IndexTable.Cell>
                  <IndexTable.Cell>
                    <Form method="post">
                      <input type="hidden" name="intent" value="delete" />
                      <input type="hidden" name="id" value={rule.id} />
                      <Button submit variant="plain" tone="critical">
                        Remove
                      </Button>
                    </Form>
                  </IndexTable.Cell>
                </IndexTable.Row>
              ))}
            </IndexTable>
          )}
        </Card>

        <AddRuleForm locations={locations} isSubmitting={isSubmitting} />
      </BlockStack>
    </Page>
  );
}

function AddRuleForm({
  locations,
  isSubmitting,
}: {
  locations: Array<{ id: string; name: string }>;
  isSubmitting: boolean;
}) {
  const [scopeType, setScopeType] = useState("vendor");
  const [scopeValue, setScopeValue] = useState("");
  const [leadTimeMin, setLeadTimeMin] = useState("");
  const [allowedMethods, setAllowedMethods] = useState<string[]>([]);
  const [allowedLocationIds, setAllowedLocationIds] = useState<string[]>([]);

  return (
    <Card>
      <Form method="post">
        {allowedMethods.map((m) => (
          <input key={m} type="hidden" name="allowedMethods" value={m} />
        ))}
        {allowedLocationIds.map((id) => (
          <input key={id} type="hidden" name="allowedLocationIds" value={id} />
        ))}
        <BlockStack gap="300">
          <Text as="h3" variant="headingSm">
            Add a product rule
          </Text>
          <InlineStack gap="300" wrap>
            <Select label="Scope" name="scopeType" options={SCOPE_TYPES} value={scopeType} onChange={setScopeType} />
            <TextField
              label={SCOPE_LABELS[scopeType] ?? "Value"}
              name="scopeValue"
              autoComplete="off"
              value={scopeValue}
              onChange={setScopeValue}
              helpText={
                scopeType === "product" || scopeType === "collection"
                  ? "The Shopify GID, e.g. gid://shopify/Product/123456789"
                  : undefined
              }
            />
            <TextField
              label="Extra prep time (minutes, optional)"
              name="leadTimeMin"
              type="number"
              autoComplete="off"
              value={leadTimeMin}
              onChange={setLeadTimeMin}
              helpText="Added on top of the slot's own lead time when this rule matches something in the cart."
            />
          </InlineStack>
          <InlineStack gap="400" wrap>
            <ChoiceList
              title="Allowed methods (leave blank for any)"
              allowMultiple
              choices={METHOD_OPTIONS}
              selected={allowedMethods}
              onChange={setAllowedMethods}
            />
            {locations.length > 0 && (
              <ChoiceList
                title="Allowed locations (leave blank for any)"
                allowMultiple
                choices={locations.map((l) => ({ label: l.name, value: l.id }))}
                selected={allowedLocationIds}
                onChange={setAllowedLocationIds}
              />
            )}
          </InlineStack>
          <div>
            <Button submit variant="primary" loading={isSubmitting}>
              Add rule
            </Button>
          </div>
        </BlockStack>
      </Form>
    </Card>
  );
}