import { useState } from "react";
import { Link, useNavigate, useParams } from "react-router-dom";
import {
  AlertTriangle,
  ArrowLeft,
  CheckCircle2,
  Sparkles,
  XCircle,
} from "lucide-react";

import { Badge } from "@/components/ui/badge";
import { Button } from "@/components/ui/button";
import {
  Card,
  CardContent,
  CardDescription,
  CardHeader,
  CardTitle,
} from "@/components/ui/card";
import {
  Dialog,
  DialogContent,
  DialogFooter,
  DialogHeader,
  DialogTitle,
  DialogTrigger,
} from "@/components/ui/dialog";
import { Label } from "@/components/ui/label";
import { Separator } from "@/components/ui/separator";
import { Skeleton } from "@/components/ui/skeleton";
import { Textarea } from "@/components/ui/textarea";
import { toast } from "@/components/ui/sonner";

import {
  useApproveExamReview,
  useExamReviewDetail,
  useRejectExamReview,
} from "@/hooks/queries/useExamReview";
import type { ExamReviewQuestion } from "@/types/exam-review";

const FAILING_THRESHOLD = 0.7;

function QuestionCard({ q, index }: { q: ExamReviewQuestion; index: number }) {
  const failing = (q.quality_score ?? 0) < FAILING_THRESHOLD;
  return (
    <Card className={failing ? "border-destructive/40" : undefined}>
      <CardHeader className="pb-3">
        <div className="flex items-start justify-between gap-3">
          <div className="min-w-0">
            <div className="flex items-center gap-2 text-xs text-muted-foreground mb-1">
              <span className="font-mono">Q{index + 1}</span>
              <span>·</span>
              <Badge variant="outline" className="capitalize">
                {q.skill}
              </Badge>
              <Badge variant="outline" className="capitalize">
                {q.question_type}
              </Badge>
              <Badge variant="outline" className="capitalize">
                {q.difficulty}
              </Badge>
              {q.ai_generated && (
                <Badge variant="secondary" className="gap-1">
                  <Sparkles className="h-3 w-3" />
                  AI
                </Badge>
              )}
            </div>
            <CardTitle className="text-sm leading-snug">
              {q.stem.length > 220 ? `${q.stem.slice(0, 220)}…` : q.stem}
            </CardTitle>
          </div>
          <Badge
            variant={
              (q.quality_score ?? 0) >= 0.85
                ? "default"
                : failing
                  ? "destructive"
                  : "secondary"
            }
            className="tabular-nums shrink-0"
          >
            {((q.quality_score ?? 0) * 100).toFixed(0)}%
          </Badge>
        </div>
      </CardHeader>
      {q.quality_report && Object.keys(q.quality_report).length > 0 && (
        <CardContent>
          <Label className="text-xs text-muted-foreground">Quality report</Label>
          <pre className="mt-1 rounded-md bg-muted/50 p-3 text-xs overflow-x-auto">
            {JSON.stringify(q.quality_report, null, 2)}
          </pre>
        </CardContent>
      )}
    </Card>
  );
}

export default function ExamReviewDetail() {
  const { examId } = useParams<{ examId: string }>();
  const navigate = useNavigate();
  const parsedId = examId ? Number(examId) : undefined;

  const { data: exam, isLoading } = useExamReviewDetail(parsedId);
  const approve = useApproveExamReview();
  const reject = useRejectExamReview();

  const [approveNotes, setApproveNotes] = useState("");
  const [rejectNotes, setRejectNotes] = useState("");
  const [approveOpen, setApproveOpen] = useState(false);
  const [rejectOpen, setRejectOpen] = useState(false);

  if (isLoading || !exam || !parsedId) {
    return (
      <div className="space-y-4">
        <Skeleton className="h-8 w-64" />
        <Skeleton className="h-40 w-full" />
        <Skeleton className="h-64 w-full" />
      </div>
    );
  }

  const handleApprove = async () => {
    try {
      await approve.mutateAsync({ examId: parsedId, notes: approveNotes });
      toast.success("Exam approved and published.");
      setApproveOpen(false);
      navigate("/admin/exam/review-queue");
    } catch (err) {
      toast.error(err instanceof Error ? err.message : "Approve failed");
    }
  };

  const handleReject = async () => {
    if (!rejectNotes.trim()) {
      toast.error("Rejection notes are required.");
      return;
    }
    try {
      await reject.mutateAsync({ examId: parsedId, notes: rejectNotes });
      toast.success("Exam rejected and returned to draft.");
      setRejectOpen(false);
      navigate("/admin/exam/review-queue");
    } catch (err) {
      toast.error(err instanceof Error ? err.message : "Reject failed");
    }
  };

  const summary = exam.summary;
  const alreadyReviewed = exam.status !== "pending_review";

  return (
    <div className="space-y-6">
      <div className="flex items-start justify-between gap-4">
        <div className="space-y-1">
          <Button asChild variant="ghost" size="sm" className="-ml-2">
            <Link to="/admin/exam/review-queue">
              <ArrowLeft className="h-4 w-4 mr-1" /> Back to queue
            </Link>
          </Button>
          <h1 className="text-2xl font-bold tracking-tight">{exam.title}</h1>
          <div className="flex items-center gap-2 text-sm text-muted-foreground">
            <Badge variant="outline" className="capitalize">
              {exam.status.replace("_", " ")}
            </Badge>
            {exam.subject_name && <span>· {exam.subject_name}</span>}
            {exam.teacher_name && <span>· Created by {exam.teacher_name}</span>}
          </div>
        </div>

        {!alreadyReviewed && (
          <div className="flex items-center gap-2">
            <Dialog open={rejectOpen} onOpenChange={setRejectOpen}>
              <DialogTrigger asChild>
                <Button variant="outline" className="gap-1">
                  <XCircle className="h-4 w-4" /> Reject
                </Button>
              </DialogTrigger>
              <DialogContent>
                <DialogHeader>
                  <DialogTitle>Reject this exam?</DialogTitle>
                </DialogHeader>
                <div className="space-y-2">
                  <Label htmlFor="reject-notes">
                    Feedback for the author (required)
                  </Label>
                  <Textarea
                    id="reject-notes"
                    value={rejectNotes}
                    onChange={(e) => setRejectNotes(e.target.value)}
                    rows={6}
                    placeholder="Explain what needs to change before this exam can be published."
                  />
                </div>
                <DialogFooter>
                  <Button
                    variant="ghost"
                    onClick={() => setRejectOpen(false)}
                    disabled={reject.isPending}
                  >
                    Cancel
                  </Button>
                  <Button
                    variant="destructive"
                    onClick={handleReject}
                    disabled={reject.isPending || !rejectNotes.trim()}
                  >
                    Reject &amp; return to draft
                  </Button>
                </DialogFooter>
              </DialogContent>
            </Dialog>

            <Dialog open={approveOpen} onOpenChange={setApproveOpen}>
              <DialogTrigger asChild>
                <Button className="gap-1">
                  <CheckCircle2 className="h-4 w-4" /> Approve &amp; publish
                </Button>
              </DialogTrigger>
              <DialogContent>
                <DialogHeader>
                  <DialogTitle>Approve and publish?</DialogTitle>
                </DialogHeader>
                <div className="space-y-2">
                  <Label htmlFor="approve-notes">Notes (optional)</Label>
                  <Textarea
                    id="approve-notes"
                    value={approveNotes}
                    onChange={(e) => setApproveNotes(e.target.value)}
                    rows={4}
                    placeholder="Any comments or context for the audit log."
                  />
                </div>
                <DialogFooter>
                  <Button
                    variant="ghost"
                    onClick={() => setApproveOpen(false)}
                    disabled={approve.isPending}
                  >
                    Cancel
                  </Button>
                  <Button
                    onClick={handleApprove}
                    disabled={approve.isPending}
                  >
                    Publish exam
                  </Button>
                </DialogFooter>
              </DialogContent>
            </Dialog>
          </div>
        )}
      </div>

      {alreadyReviewed && exam.reviewed_by_name && (
        <Card>
          <CardHeader className="pb-2">
            <CardTitle className="text-sm">Previously reviewed</CardTitle>
            <CardDescription>
              {exam.reviewed_by_name}
              {exam.reviewed_at ? ` · ${new Date(exam.reviewed_at).toLocaleString()}` : ""}
            </CardDescription>
          </CardHeader>
          {exam.review_notes && (
            <CardContent className="text-sm whitespace-pre-wrap">
              {exam.review_notes}
            </CardContent>
          )}
        </Card>
      )}

      <Card>
        <CardHeader>
          <CardTitle className="text-base">Quality summary</CardTitle>
          <CardDescription>
            Aggregated across every question in this exam.
          </CardDescription>
        </CardHeader>
        <CardContent>
          <div className="grid grid-cols-2 md:grid-cols-4 gap-4 text-sm">
            <div>
              <div className="text-muted-foreground">Questions</div>
              <div className="text-2xl font-semibold tabular-nums">
                {summary.question_count}
              </div>
            </div>
            <div>
              <div className="text-muted-foreground">Average quality</div>
              <div className="text-2xl font-semibold tabular-nums">
                {(summary.avg_quality_score * 100).toFixed(0)}%
              </div>
            </div>
            <div>
              <div className="text-muted-foreground">Lowest score</div>
              <div className="text-2xl font-semibold tabular-nums">
                {(summary.min_quality_score * 100).toFixed(0)}%
              </div>
            </div>
            <div>
              <div className="text-muted-foreground flex items-center gap-1">
                <AlertTriangle className="h-3 w-3" /> Failing
              </div>
              <div className="text-2xl font-semibold tabular-nums text-destructive">
                {summary.failing_count}
              </div>
            </div>
          </div>
        </CardContent>
      </Card>

      <Separator />

      <div className="space-y-3">
        {exam.sections.length === 0 ? (
          <p className="text-sm text-muted-foreground">
            This exam has no sections yet.
          </p>
        ) : (
          exam.sections.map((section) => (
            <section key={section.id} className="space-y-3">
              <h2 className="text-base font-semibold flex items-center gap-2">
                <span>{section.title}</span>
                <Badge variant="outline" className="capitalize text-xs">
                  {section.skill || "general"}
                </Badge>
                <span className="text-sm font-normal text-muted-foreground">
                  · {section.questions.length} questions
                </span>
              </h2>
              <div className="space-y-2">
                {section.questions.map((q, idx) => (
                  <QuestionCard key={q.id} q={q} index={idx} />
                ))}
              </div>
            </section>
          ))
        )}
      </div>
    </div>
  );
}