import { useMemo } from "react";
import {
  useListCompareTools,
  getListCompareToolsQueryKey,
  type ToolWithStats,
} from "@workspace/api-client-react";
import { Link, useSearch } from "wouter";
import { Layout } from "@/components/layout";
import { useAuth } from "@/hooks/use-auth";
import { RatingStars } from "@/components/rating-stars";
import { Badge } from "@/components/ui/badge";
import { Button } from "@/components/ui/button";
import { Skeleton } from "@/components/ui/skeleton";
import { Card, CardContent, CardHeader, CardTitle, CardDescription } from "@/components/ui/card";
import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table";
import { ShieldAlert, Trophy, Scale } from "lucide-react";
import { cn } from "@/lib/utils";
import { useTranslation } from "react-i18next";

function fmt(v: number | null | undefined): string {
  return v != null ? v.toFixed(1) : "–";
}

export default function Compare() {
  const { t } = useTranslation();
  const { hasFeature, isLoading: authLoading } = useAuth();
  const search = useSearch();

  const params = useMemo(() => {
    const ids = new URLSearchParams(search)
      .get("ids")
      ?.split(",")
      .map((s) => Number(s.trim()))
      .filter((n) => Number.isInteger(n) && n > 0);
    return ids && ids.length > 0 ? { ids: ids.join(",") } : undefined;
  }, [search]);

  const canCompare = hasFeature("compare");

  const { data: tools, isLoading: loading } = useListCompareTools(
    params ?? { ids: "" },
    {
      query: {
        queryKey: getListCompareToolsQueryKey(params ?? { ids: "" }),
        enabled: !!params && canCompare,
      },
    },
  );

  if (!authLoading && !canCompare) {
    return (
      <Layout>
        <div className="flex flex-col items-center justify-center py-20 gap-4">
          <ShieldAlert className="w-12 h-12 text-muted-foreground" />
          <h2 className="text-2xl font-bold">{t("compare.requiresPremium")}</h2>
          <p className="text-muted-foreground">{t("compare.requiresPremiumSub")}</p>
          <Button variant="outline" asChild>
            <a href="/tools">{t("common.backToTools")}</a>
          </Button>
        </div>
      </Layout>
    );
  }

  if (loading) {
    return (
      <Layout>
        <div className="space-y-6">
          <Skeleton className="h-8 w-48" />
          <Skeleton className="h-64 w-full" />
        </div>
      </Layout>
    );
  }

  const list = tools ?? [];
  if (list.length === 0) {
    return (
      <Layout>
        <div className="flex flex-col items-center justify-center py-20 gap-4">
          <Scale className="w-12 h-12 text-muted-foreground" />
          <h2 className="text-2xl font-bold">{t("compare.nothingToCompare")}</h2>
          <p className="text-muted-foreground">{t("compare.nothingToCompareSub")}</p>
          <Button variant="outline" asChild>
            <a href="/tools">{t("common.browseTools")}</a>
          </Button>
        </div>
      </Layout>
    );
  }

  const bestRating = Math.max(...list.map((t) => t.avgCombined ?? 0));
  const bestUsefulness = Math.max(...list.map((t) => t.avgUsefulness ?? 0));
  const bestUsability = Math.max(...list.map((t) => t.avgUsability ?? 0));
  const bestReviews = Math.max(...list.map((t) => t.ratingCount));

  const isBest = (value: number | null, best: number) =>
    value != null && value > 0 && value >= best && value === best;

  return (
    <Layout>
      <div className="space-y-6 pb-10">
        <div>
          <h1 className="text-3xl font-bold tracking-tight mb-2">{t("compare.title")}</h1>
          <p className="text-muted-foreground">{t("compare.subtitle", { count: list.length })}</p>
        </div>

        <Card>
          <CardHeader>
            <CardTitle>{t("compare.sideBySide")}</CardTitle>
            <CardDescription>{t("compare.bestValue")}</CardDescription>
          </CardHeader>
          <CardContent className="overflow-x-auto">
            <Table>
              <TableHeader>
                <TableRow>
                  <TableHead className="w-44">{t("compare.attribute")}</TableHead>
                  {list.map((t) => (
                    <TableHead key={t.id} className="min-w-[12rem]">
                      <div className="flex flex-col gap-1">
                        <Link to={`/tools/${t.id}`} className="font-semibold hover:text-primary hover:underline">
                          {t.name}
                        </Link>
                        <Badge variant="outline" className="w-fit text-[10px]">{t.category}</Badge>
                      </div>
                    </TableHead>
                  ))}
                </TableRow>
              </TableHeader>
              <TableBody>
                <TableRow>
                  <TableCell className="font-medium">{t("compare.rating")}</TableCell>
                  {list.map((t) => (
                    <TableCell key={t.id} className={cn(isBest(t.avgCombined, bestRating) && "bg-primary/5")}>
                      <div className="flex items-center gap-2">
                        <RatingStars value={t.avgCombined ?? 0} size="sm" />
                        <span className="font-semibold tabular-nums">{fmt(t.avgCombined)}/5</span>
                        {isBest(t.avgCombined, bestRating) && <Trophy className="w-3.5 h-3.5 text-primary" />}
                      </div>
                    </TableCell>
                  ))}
                </TableRow>
                <TableRow>
                  <TableCell className="font-medium">Usefulness</TableCell>
                  {list.map((t) => (
                    <TableCell key={t.id} className={cn(isBest(t.avgUsefulness, bestUsefulness) && "bg-primary/5")}>
                      <span className="tabular-nums">{fmt(t.avgUsefulness)}/5</span>
                    </TableCell>
                  ))}
                </TableRow>
                <TableRow>
                  <TableCell className="font-medium">Usability</TableCell>
                  {list.map((t) => (
                    <TableCell key={t.id} className={cn(isBest(t.avgUsability, bestUsability) && "bg-primary/5")}>
                      <span className="tabular-nums">{fmt(t.avgUsability)}/5</span>
                    </TableCell>
                  ))}
                </TableRow>
                <TableRow>
                  <TableCell className="font-medium">{t("compare.reviews")}</TableCell>
                  {list.map((t) => (
                    <TableCell key={t.id} className={cn(isBest(t.ratingCount, bestReviews) && "bg-primary/5")}>
                      <span className="tabular-nums">{t.ratingCount}</span>
                    </TableCell>
                  ))}
                </TableRow>
                <TableRow>
                  <TableCell className="font-medium">{t("compare.description")}</TableCell>
                  {list.map((t) => (
                    <TableCell key={t.id} className="text-sm text-muted-foreground align-top">
                      {t.description}
                    </TableCell>
                  ))}
                </TableRow>
                <TableRow>
                  <TableCell className="font-medium">Features</TableCell>
                  {list.map((t) => (
                    <TableCell key={t.id} className="align-top">
                      <div className="flex flex-wrap gap-1">
                        {(t.features ?? []).map((f) => (
                          <Badge key={f} variant="secondary" className="text-[10px]">{f}</Badge>
                        ))}
                        {(t.features?.length ?? 0) === 0 && <span className="text-muted-foreground">—</span>}
                      </div>
                    </TableCell>
                  ))}
                </TableRow>
                <TableRow>
                  <TableCell className="font-medium">Tags</TableCell>
                  {list.map((t) => (
                    <TableCell key={t.id} className="align-top">
                      <div className="flex flex-wrap gap-1">
                        {(t.tags ?? []).map((tag) => (
                          <Badge key={tag} variant="outline" className="text-[10px]">{tag}</Badge>
                        ))}
                        {(t.tags?.length ?? 0) === 0 && <span className="text-muted-foreground">—</span>}
                      </div>
                    </TableCell>
                  ))}
                </TableRow>
                <TableRow>
                  <TableCell className="font-medium">{t("compare.lastUpdated")}</TableCell>
                  {list.map((t) => (
                    <TableCell key={t.id} className="text-sm text-muted-foreground">
                      {new Date(t.updatedAt).toLocaleDateString()}
                    </TableCell>
                  ))}
                </TableRow>
              </TableBody>
            </Table>
          </CardContent>
        </Card>

        <Button variant="outline" asChild>
          <Link to="/tools">{t("compare.backToBrowse")}</Link>
        </Button>
      </div>
    </Layout>
  );
}