"use client";

import { useEffect, useMemo, useState } from "react";

import { NoPermissionState } from "@/components/auth/no-permission-state";
import { useSuperAdminSession } from "@/components/auth/session-context";
import { ChannelPieChart, InsightBarChart } from "@/components/dashboard/charts";
import { PageHeader } from "@/components/dashboard/page-header";
import { StatCard } from "@/components/dashboard/stat-card";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import { EmptyState } from "@/components/ui/empty-state";
import { useToast } from "@/components/ui/toast";
import { getSuperAdminCharts, getSuperAdminOverview } from "@/lib/api/superadmin";
import { SUPERADMIN_PERMISSIONS, hasPermission } from "@/lib/permissions";
import type {
  SuperAdminBreakdownItem,
  SuperAdminChartsResponse,
  SuperAdminChartPoint,
  SuperAdminOverviewResponse,
} from "@/types/api";
import type { ChannelPoint, Insight, StatMetric } from "@/types";

type AnalyticsSnapshot = {
  overview: SuperAdminOverviewResponse | null;
  charts: SuperAdminChartsResponse | null;
};

function toInsight(points: SuperAdminChartPoint[]): Insight[] {
  return points.map((point) => ({ label: point.label, value: point.count }));
}

function toInsightBreakdown(items: SuperAdminBreakdownItem[]): Insight[] {
  return items.map((item) => ({ label: item.label, value: item.value }));
}

function toChannel(items: SuperAdminBreakdownItem[]): ChannelPoint[] {
  return items.map((item) => ({ name: item.label, value: item.value }));
}

export default function AnalyticsPage() {
  const { permissions } = useSuperAdminSession();
  const [snapshot, setSnapshot] = useState<AnalyticsSnapshot>({
    overview: null,
    charts: null,
  });
  const [loading, setLoading] = useState(true);
  const { toast } = useToast();

  const canReadAnalytics = hasPermission(permissions, SUPERADMIN_PERMISSIONS.ANALYTICS_READ);
  const canReadOverview = hasPermission(permissions, SUPERADMIN_PERMISSIONS.OVERVIEW_READ);

  useEffect(() => {
    let active = true;

    const loadAnalytics = async () => {
      if (!canReadAnalytics) {
        setLoading(false);
        return;
      }

      setLoading(true);
      try {
        const [overview, charts] = await Promise.all([
          canReadOverview ? getSuperAdminOverview() : Promise.resolve(null),
          getSuperAdminCharts({ range: "30d" }),
        ]);

        if (!active) return;
        setSnapshot({ overview, charts });
      } catch (error) {
        if (!active) return;
        toast({ title: "Failed to load analytics", description: String(error), variant: "danger" });
      } finally {
        if (active) setLoading(false);
      }
    };

    void loadAnalytics();

    return () => {
      active = false;
    };
  }, [canReadAnalytics, canReadOverview, toast]);

  const metrics = snapshot.overview?.metrics;

  const dashboardMetrics: StatMetric[] = useMemo(
    () => [
      {
        id: "users",
        label: "Total users",
        value: loading ? "..." : String(metrics?.usersCount ?? 0),
        delta: `${metrics?.adminsCount ?? 0} admin accounts`,
        trend: "up",
      },
      {
        id: "posts",
        label: "Published content",
        value: loading ? "..." : String(metrics?.postsCount ?? 0),
        delta: `${metrics?.commentsCount ?? 0} tracked comments`,
        trend: "up",
      },
      {
        id: "marketplace",
        label: "Marketplace",
        value: loading ? "..." : String(metrics?.marketplaceListingsCount ?? 0),
        delta: `${metrics?.repairShopsCount ?? 0} repair shops`,
        trend: "neutral",
      },
      {
        id: "moderation",
        label: "Moderation load",
        value: loading
          ? "..."
          : String((metrics?.flaggedPostsCount ?? 0) + (metrics?.flaggedCommentsCount ?? 0)),
        delta: `${metrics?.hiddenPostsCount ?? 0} hidden posts and ${metrics?.hiddenCommentsCount ?? 0} hidden comments`,
        trend:
          (metrics?.flaggedPostsCount ?? 0) + (metrics?.flaggedCommentsCount ?? 0) > 0
            ? "down"
            : "neutral",
      },
    ],
    [loading, metrics],
  );

  const charts = snapshot.charts;
  const userSeries = toInsight(charts?.series.users ?? []);
  const postSeries = toInsight(charts?.series.posts ?? []);
  const listingSeries = toInsight(charts?.series.listings ?? []);
  const roleBreakdown = toChannel(charts?.breakdowns.userRoles ?? []);
  const listingBreakdown = toInsightBreakdown(charts?.breakdowns.listingCategories ?? []);
  const moderationBreakdown = toInsightBreakdown(charts?.breakdowns.moderation ?? []);

  if (!canReadAnalytics) {
    return (
      <div className="space-y-5 pb-8">
        <PageHeader
          title="Analytics"
          subtitle="Charts and operational trends for users, content, moderation, and marketplace activity."
        />
        <NoPermissionState description="This page needs the analytics.read permission." />
      </div>
    );
  }

  return (
    <div className="space-y-5 pb-8">
      <PageHeader
        title="Analytics"
        subtitle="Operational charts for growth, moderation, and marketplace activity."
      />

      {canReadOverview ? (
        <section className="grid gap-4 md:grid-cols-2 xl:grid-cols-4">
          {dashboardMetrics.map((metric) => (
            <StatCard key={metric.id} metric={metric} />
          ))}
        </section>
      ) : null}

      <section className="grid gap-4 xl:grid-cols-12">
        <Card className="xl:col-span-6">
          <CardHeader>
            <CardTitle>User signups - last 30 days</CardTitle>
          </CardHeader>
          <CardContent>
            {userSeries.length ? (
              <InsightBarChart data={userSeries} />
            ) : (
              <EmptyState title="No data" description="Not enough user activity to draw this chart." />
            )}
          </CardContent>
        </Card>

        <Card className="xl:col-span-6">
          <CardHeader>
            <CardTitle>Published content - last 30 days</CardTitle>
          </CardHeader>
          <CardContent>
            {postSeries.length ? (
              <InsightBarChart data={postSeries} />
            ) : (
              <EmptyState title="No data" description="Not enough content activity to draw this chart." />
            )}
          </CardContent>
        </Card>
      </section>

      <section className="grid gap-4 xl:grid-cols-12">
        <Card className="xl:col-span-5">
          <CardHeader>
            <CardTitle>User role distribution</CardTitle>
          </CardHeader>
          <CardContent>
            {roleBreakdown.length ? (
              <ChannelPieChart data={roleBreakdown} />
            ) : (
              <EmptyState title="No role data" description="No role breakdown is currently available." />
            )}
          </CardContent>
        </Card>

        <Card className="xl:col-span-7">
          <CardHeader>
            <CardTitle>Marketplace categories</CardTitle>
          </CardHeader>
          <CardContent>
            {listingBreakdown.length ? (
              <InsightBarChart data={listingBreakdown} />
            ) : (
              <EmptyState title="No data" description="No category breakdown is available right now." />
            )}
          </CardContent>
        </Card>
      </section>

      <section className="grid gap-4 xl:grid-cols-12">
        <Card className="xl:col-span-6">
          <CardHeader>
            <CardTitle>Marketplace creation - last 30 days</CardTitle>
          </CardHeader>
          <CardContent>
            {listingSeries.length ? (
              <InsightBarChart data={listingSeries} />
            ) : (
              <EmptyState title="No data" description="Not enough marketplace activity to draw this chart." />
            )}
          </CardContent>
        </Card>

        <Card className="xl:col-span-6">
          <CardHeader>
            <CardTitle>Current moderation states</CardTitle>
          </CardHeader>
          <CardContent>
            {moderationBreakdown.length ? (
              <InsightBarChart data={moderationBreakdown} />
            ) : (
              <EmptyState title="No data" description="No moderation breakdown is available right now." />
            )}
          </CardContent>
        </Card>
      </section>
    </div>
  );
}