import React, { useState, useEffect } from "react";
import type { User, Asset } from "../../../types";
import { apiClient } from "../../../lib/api-client";
import {
  Users,
  FileStack,
  DownloadCloud,
  AlertTriangle,
  Cpu,
  Terminal,
  Brain,
  Server,
  ShieldCheck,
} from "lucide-react";

export const AnalyticsDashboard: React.FC = () => {
  const [clients, setClients] = useState<User[]>([]);
  const [assets, setAssets] = useState<Asset[]>([]);
  const [loading, setLoading] = useState(true);

  const fetchStats = async () => {
    setLoading(true);
    try {
      const clientRes = await apiClient.get<User[]>("/admin/clients");
      const assetRes = await apiClient.get<Asset[]>("/assets");
      setClients(clientRes.data);
      setAssets(assetRes.data);
    } catch (err) {
      console.error(err);
    } finally {
      setLoading(false);
    }
  };

  useEffect(() => {
    fetchStats();
  }, []);

  // Compute analytics data
  const totalClients = clients.length;
  const totalAssets = assets.length;
  const totalDownloads = assets.reduce((sum, a) => sum + a.downloadsCount, 0);
  const pendingApprovals = clients.filter(
    (c) => c.onboardingStatus === "PENDING_APPROVAL",
  ).length;

  // Category counts
  const categoryCounts = assets.reduce(
    (acc, a) => {
      acc[a.categoryId] = (acc[a.categoryId] || 0) + 1;
      return acc;
    },
    { silicon: 0, software: 0, ai: 0, cloud: 0 } as Record<string, number>,
  );

  const categoryMax = Math.max(...Object.values(categoryCounts), 1);

  // Onboarding Status distributions
  const onboardingCounts = clients.reduce(
    (acc, c) => {
      acc[c.onboardingStatus] = (acc[c.onboardingStatus] || 0) + 1;
      return acc;
    },
    {
      NOT_STARTED: 0,
      FORM_COMPLETED: 0,
      NDA_SIGNED: 0,
      PENDING_APPROVAL: 0,
      APPROVED: 0,
      REJECTED: 0,
    } as Record<string, number>,
  );

  const onboardingMax = Math.max(...Object.values(onboardingCounts), 1);

  return (
    <div className="space-y-6">
      <div>
        <h2 className="text-xl font-bold text-ink-800">
          Operational Analytics
        </h2>
        <p className="text-sm text-ink-600">
          Overview of client onboarding metrics, asset repository distribution,
          and core library downloads.
        </p>
      </div>

      {loading ? (
        <div className="grid gap-4 sm:grid-cols-2 lg:grid-cols-4">
          {[1, 2, 3, 4].map((n) => (
            <div
              key={n}
              className="h-28 animate-pulse rounded-xl bg-white border border-ink-100"
            />
          ))}
        </div>
      ) : (
        /* Metric Cards */
        <div className="grid gap-5 sm:grid-cols-2 lg:grid-cols-4">
          <div className="rounded-xl border border-ink-100 bg-white p-5 shadow-sm flex items-center gap-4 hover:shadow-premium transition-all duration-300">
            <div className="rounded-lg bg-primary-50 p-3 text-primary-700">
              <Users className="h-6 w-6" />
            </div>
            <div>
              <p className="text-[10px] font-bold uppercase tracking-wider text-ink-600">
                Total Clients
              </p>
              <p className="text-2xl font-bold text-ink-800">{totalClients}</p>
            </div>
          </div>

          <div className="rounded-xl border border-ink-100 bg-white p-5 shadow-sm flex items-center gap-4 hover:shadow-premium transition-all duration-300">
            <div className="rounded-lg bg-primary-50 p-3 text-primary-700">
              <FileStack className="h-6 w-6" />
            </div>
            <div>
              <p className="text-[10px] font-bold uppercase tracking-wider text-ink-600">
                Active Assets
              </p>
              <p className="text-2xl font-bold text-ink-800">{totalAssets}</p>
            </div>
          </div>

          <div className="rounded-xl border border-ink-100 bg-white p-5 shadow-sm flex items-center gap-4 hover:shadow-premium transition-all duration-300">
            <div className="rounded-lg bg-primary-50 p-3 text-primary-700">
              <DownloadCloud className="h-6 w-6" />
            </div>
            <div>
              <p className="text-[10px] font-bold uppercase tracking-wider text-ink-600">
                Total Downloads
              </p>
              <p className="text-2xl font-bold text-ink-800">
                {totalDownloads}
              </p>
            </div>
          </div>

          <div className="rounded-xl border border-ink-100 bg-white p-5 shadow-sm flex items-center gap-4 hover:shadow-premium transition-all duration-300">
            <div
              className={`rounded-lg p-3 ${pendingApprovals > 0 ? "bg-warning/10 text-warning" : "bg-success/10 text-success"}`}
            >
              <AlertTriangle className="h-6 w-6" />
            </div>
            <div>
              <p className="text-[10px] font-bold uppercase tracking-wider text-ink-600">
                Pending Review
              </p>
              <p className="text-2xl font-bold text-ink-800">
                {pendingApprovals}
              </p>
            </div>
          </div>
        </div>
      )}

      {/* Charts Grid */}
      <div className="grid gap-6 md:grid-cols-2">
        {/* Category Breakdown */}
        <div className="rounded-xl border border-ink-100 bg-white p-5 shadow-sm space-y-4">
          <div className="flex items-center justify-between">
            <h3 className="text-sm font-bold text-ink-800">
              Assets by Domain Category
            </h3>
            <span className="text-[10px] uppercase font-bold tracking-wider text-ink-600">
              Count
            </span>
          </div>

          {loading ? (
            <div className="space-y-4 py-6">
              {[1, 2, 3].map((n) => (
                <div key={n} className="h-8 animate-pulse rounded bg-ink-50" />
              ))}
            </div>
          ) : (
            <div className="space-y-4 py-2">
              {[
                { key: "silicon", name: "Silicon Core IP", icon: Cpu },
                {
                  key: "software",
                  name: "Software & Libraries",
                  icon: Terminal,
                },
                { key: "ai", name: "AI & Agent Workflows", icon: Brain },
                { key: "cloud", name: "Cloud Configs & IaC", icon: Server },
              ].map((item) => {
                const count = categoryCounts[item.key] || 0;
                const percentage = (count / categoryMax) * 100;
                const Icon = item.icon;

                return (
                  <div key={item.key} className="space-y-1">
                    <div className="flex items-center justify-between text-xs">
                      <span className="flex items-center gap-1.5 font-semibold text-ink-700">
                        <Icon className="h-4 w-4 text-primary-700" />
                        {item.name}
                      </span>
                      <span className="font-mono font-bold text-ink-800">
                        {count}
                      </span>
                    </div>
                    <div className="h-3.5 w-full rounded-full bg-ink-50 overflow-hidden border border-ink-100/50">
                      <div
                        className="h-full rounded-full bg-gradient-to-r from-primary-200 to-primary-400 transition-all duration-500"
                        style={{ width: `${percentage}%` }}
                      />
                    </div>
                  </div>
                );
              })}
            </div>
          )}
        </div>

        {/* Client Onboarding Funnel */}
        <div className="rounded-xl border border-ink-100 bg-white p-5 shadow-sm space-y-4">
          <div className="flex items-center justify-between">
            <h3 className="text-sm font-bold text-ink-800">
              Client Onboarding Funnel
            </h3>
            <span className="text-[10px] uppercase font-bold tracking-wider text-ink-600">
              Accounts
            </span>
          </div>

          {loading ? (
            <div className="space-y-4 py-6">
              {[1, 2, 3].map((n) => (
                <div key={n} className="h-8 animate-pulse rounded bg-ink-50" />
              ))}
            </div>
          ) : (
            <div className="space-y-4 py-2">
              {[
                { key: "NOT_STARTED", name: "Registration Initiated" },
                { key: "FORM_COMPLETED", name: "Profile Form Saved" },
                { key: "NDA_SIGNED", name: "NDA Document Signed" },
                { key: "PENDING_APPROVAL", name: "Awaiting Admin Approval" },
                { key: "APPROVED", name: "Approved & Active Portal" },
              ].map((item) => {
                const count = onboardingCounts[item.key] || 0;
                const percentage = (count / onboardingMax) * 100;

                return (
                  <div key={item.key} className="space-y-1">
                    <div className="flex items-center justify-between text-xs">
                      <span className="font-semibold text-ink-700">
                        {item.name}
                      </span>
                      <span className="font-mono font-bold text-ink-800">
                        {count}
                      </span>
                    </div>
                    <div className="h-3.5 w-full rounded-full bg-ink-50 overflow-hidden border border-ink-100/50">
                      <div
                        className={`h-full rounded-full transition-all duration-500 ${
                          item.key === "APPROVED"
                            ? "bg-success/70"
                            : item.key === "PENDING_APPROVAL"
                              ? "bg-warning/70"
                              : "bg-primary-300"
                        }`}
                        style={{ width: `${percentage}%` }}
                      />
                    </div>
                  </div>
                );
              })}
            </div>
          )}
        </div>
      </div>

      {/* Bottom list showing Top Downloaded Assets */}
      <div className="rounded-xl border border-ink-100 bg-white p-5 shadow-sm space-y-4">
        <h3 className="text-sm font-bold text-ink-800">
          Most Downloaded Catalog Resources
        </h3>
        <div className="divide-y divide-ink-50">
          {assets
            .slice()
            .sort((a, b) => b.downloadsCount - a.downloadsCount)
            .slice(0, 3)
            .map((asset, index) => (
              <div
                key={asset.id}
                className="flex items-center justify-between py-2.5 first:pt-0 last:pb-0"
              >
                <div className="flex items-center gap-3">
                  <span className="flex h-6 w-6 items-center justify-center rounded-full bg-primary-50 text-xs font-bold text-primary-800 border border-primary-100">
                    {index + 1}
                  </span>
                  <div>
                    <p className="text-xs font-bold text-ink-800">
                      {asset.title}
                    </p>
                    <p className="text-[10px] text-ink-600 font-semibold">
                      {asset.subcategory}
                    </p>
                  </div>
                </div>
                <div className="flex items-center gap-1.5 text-xs text-ink-700 font-mono">
                  <ShieldCheck className="h-4 w-4 text-success" />
                  <span className="font-bold">{asset.downloadsCount}</span>{" "}
                  downloads
                </div>
              </div>
            ))}
        </div>
      </div>
    </div>
  );
};