import { useState } from "react";
import { Button } from "@/components/ui/button";
import { Badge } from "@/components/ui/badge";
import { Tabs, TabsContent, TabsList, TabsTrigger } from "@/components/ui/tabs";
import { useIndexAdvisorReport, useApplyIndexRecommendation } from "@/hooks/use-index-advisor";
import { RecommendationCard } from "./RecommendationCard";
import { toast } from "sonner";
import { Loader2, Gauge, Search, AlertTriangle } from "lucide-react";
import type { IndexAdvisorReport } from "@/types";

interface Props {
  connectionId: string;
}

export function IndexAdvisorPanel({ connectionId }: Props) {
  const [report, setReport] = useState<IndexAdvisorReport | null>(null);
  const [appliedDdls, setAppliedDdls] = useState<Set<string>>(new Set());
  const [applyingDdl, setApplyingDdl] = useState<string | null>(null);

  const reportMutation = useIndexAdvisorReport();
  const applyMutation = useApplyIndexRecommendation();

  const handleAnalyze = () => {
    reportMutation.mutate(connectionId, {
      onSuccess: (data) => {
        setReport(data);
        setAppliedDdls(new Set());
      },
      onError: (err) => toast.error("Analysis failed", { description: String(err) }),
    });
  };

  const handleApply = async (ddl: string) => {
    if (!confirm("Apply this index change? This will modify the database schema.")) return;

    setApplyingDdl(ddl);
    try {
      await applyMutation.mutateAsync({ connectionId, ddl });
      setAppliedDdls((prev) => new Set(prev).add(ddl));
      toast.success("Index change applied");
    } catch (err) {
      toast.error("Failed to apply", { description: String(err) });
    } finally {
      setApplyingDdl(null);
    }
  };

  return (
    <div className="flex h-full flex-col">
      {/* Header */}
      <div className="border-b px-4 py-3 flex items-center justify-between">
        <div className="flex items-center gap-2">
          <Gauge className="h-5 w-5 text-primary" />
          <h2 className="text-sm font-medium">Index Advisor</h2>
        </div>
        <Button
          size="sm"
          onClick={handleAnalyze}
          disabled={reportMutation.isPending}
        >
          {reportMutation.isPending ? (
            <><Loader2 className="h-3.5 w-3.5 animate-spin mr-1" />Analyzing...</>
          ) : (
            <><Search className="h-3.5 w-3.5 mr-1" />Analyze</>
          )}
        </Button>
      </div>

      {/* Content */}
      <div className="flex-1 overflow-auto">
        {!report ? (
          <div className="flex h-full items-center justify-center text-sm text-muted-foreground">
            Click Analyze to scan your database for index optimization opportunities.
          </div>
        ) : (
          <Tabs defaultValue="recommendations" className="h-full flex flex-col">
            <div className="border-b px-4">
              <TabsList className="h-9">
                <TabsTrigger value="recommendations" className="text-xs">
                  Recommendations
                  {report.recommendations.length > 0 && (
                    <Badge variant="secondary" className="ml-1 text-[10px]">{report.recommendations.length}</Badge>
                  )}
                </TabsTrigger>
                <TabsTrigger value="table-stats" className="text-xs">Table Stats</TabsTrigger>
                <TabsTrigger value="index-stats" className="text-xs">Index Stats</TabsTrigger>
                <TabsTrigger value="slow-queries" className="text-xs">
                  Slow Queries
                  {!report.has_pg_stat_statements && (
                    <AlertTriangle className="h-3 w-3 ml-1 text-yellow-500" />
                  )}
                </TabsTrigger>
              </TabsList>
            </div>

            <TabsContent value="recommendations" className="flex-1 overflow-auto p-4 space-y-2 mt-0">
              {report.recommendations.length === 0 ? (
                <div className="text-sm text-muted-foreground text-center py-8">
                  No recommendations found. Your indexes look good!
                </div>
              ) : (
                report.recommendations.map((rec, i) => (
                  <RecommendationCard
                    key={rec.id || i}
                    recommendation={rec}
                    onApply={handleApply}
                    isApplying={applyingDdl === rec.ddl}
                    applied={appliedDdls.has(rec.ddl)}
                  />
                ))
              )}
            </TabsContent>

            <TabsContent value="table-stats" className="flex-1 overflow-auto mt-0">
              <div className="overflow-x-auto">
                <table className="w-full text-xs">
                  <thead>
                    <tr className="border-b bg-muted/50">
                      <th className="px-3 py-2 text-left font-medium">Table</th>
                      <th className="px-3 py-2 text-right font-medium">Seq Scans</th>
                      <th className="px-3 py-2 text-right font-medium">Idx Scans</th>
                      <th className="px-3 py-2 text-right font-medium">Rows</th>
                      <th className="px-3 py-2 text-right font-medium">Table Size</th>
                      <th className="px-3 py-2 text-right font-medium">Index Size</th>
                    </tr>
                  </thead>
                  <tbody>
                    {report.table_stats.map((ts) => {
                      const ratio = ts.seq_scan + ts.idx_scan > 0
                        ? ts.seq_scan / (ts.seq_scan + ts.idx_scan)
                        : 0;
                      return (
                        <tr key={`${ts.schema}.${ts.table}`} className="border-b">
                          <td className="px-3 py-2 font-mono">{ts.schema}.{ts.table}</td>
                          <td className={`px-3 py-2 text-right ${ratio > 0.8 && ts.n_live_tup > 1000 ? "text-destructive font-medium" : ""}`}>
                            {ts.seq_scan.toLocaleString()}
                          </td>
                          <td className="px-3 py-2 text-right">{ts.idx_scan.toLocaleString()}</td>
                          <td className="px-3 py-2 text-right">{ts.n_live_tup.toLocaleString()}</td>
                          <td className="px-3 py-2 text-right">{ts.table_size}</td>
                          <td className="px-3 py-2 text-right">{ts.index_size}</td>
                        </tr>
                      );
                    })}
                  </tbody>
                </table>
              </div>
            </TabsContent>

            <TabsContent value="index-stats" className="flex-1 overflow-auto mt-0">
              <div className="overflow-x-auto">
                <table className="w-full text-xs">
                  <thead>
                    <tr className="border-b bg-muted/50">
                      <th className="px-3 py-2 text-left font-medium">Index</th>
                      <th className="px-3 py-2 text-left font-medium">Table</th>
                      <th className="px-3 py-2 text-right font-medium">Scans</th>
                      <th className="px-3 py-2 text-right font-medium">Size</th>
                      <th className="px-3 py-2 text-left font-medium">Definition</th>
                    </tr>
                  </thead>
                  <tbody>
                    {report.index_stats.map((is) => (
                      <tr key={`${is.schema}.${is.index_name}`} className="border-b">
                        <td className={`px-3 py-2 font-mono ${is.idx_scan === 0 ? "text-yellow-600" : ""}`}>
                          {is.index_name}
                        </td>
                        <td className="px-3 py-2">{is.schema}.{is.table}</td>
                        <td className={`px-3 py-2 text-right ${is.idx_scan === 0 ? "text-yellow-600 font-medium" : ""}`}>
                          {is.idx_scan.toLocaleString()}
                        </td>
                        <td className="px-3 py-2 text-right">{is.index_size}</td>
                        <td className="px-3 py-2 font-mono text-muted-foreground max-w-xs truncate">
                          {is.definition}
                        </td>
                      </tr>
                    ))}
                  </tbody>
                </table>
              </div>
            </TabsContent>

            <TabsContent value="slow-queries" className="flex-1 overflow-auto mt-0">
              {!report.has_pg_stat_statements ? (
                <div className="p-4 text-sm text-muted-foreground">
                  <div className="flex items-center gap-2 mb-2">
                    <AlertTriangle className="h-4 w-4 text-yellow-500" />
                    pg_stat_statements extension is not installed
                  </div>
                  <p className="text-xs">
                    Enable it with: CREATE EXTENSION pg_stat_statements;
                  </p>
                </div>
              ) : report.slow_queries.length === 0 ? (
                <div className="p-4 text-sm text-muted-foreground text-center">
                  No slow queries found.
                </div>
              ) : (
                <div className="overflow-x-auto">
                  <table className="w-full text-xs">
                    <thead>
                      <tr className="border-b bg-muted/50">
                        <th className="px-3 py-2 text-left font-medium">Query</th>
                        <th className="px-3 py-2 text-right font-medium">Calls</th>
                        <th className="px-3 py-2 text-right font-medium">Mean (ms)</th>
                        <th className="px-3 py-2 text-right font-medium">Total (ms)</th>
                        <th className="px-3 py-2 text-right font-medium">Rows</th>
                      </tr>
                    </thead>
                    <tbody>
                      {report.slow_queries.map((sq, i) => (
                        <tr key={i} className="border-b">
                          <td className="px-3 py-2 font-mono max-w-md truncate" title={sq.query}>
                            {sq.query.substring(0, 150)}
                          </td>
                          <td className="px-3 py-2 text-right">{sq.calls.toLocaleString()}</td>
                          <td className="px-3 py-2 text-right">{sq.mean_time_ms.toFixed(1)}</td>
                          <td className="px-3 py-2 text-right">{sq.total_time_ms.toFixed(0)}</td>
                          <td className="px-3 py-2 text-right">{sq.rows.toLocaleString()}</td>
                        </tr>
                      ))}
                    </tbody>
                  </table>
                </div>
              )}
            </TabsContent>
          </Tabs>
        )}
      </div>
    </div>
  );
}