import { useEffect, useMemo, useState } from "react";
import { useParams } from "react-router-dom";
import {
  useGradingQueue,
  useStudentResponse,
  useGradingRubric,
  useAIGradeSuggestion,
  useSubmitGrade,
} from "@/hooks/queries/useGrading";
import type { GradingQueueItem } from "@/types";
import { Button } from "@/components/ui/button";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import {
  Table,
  TableBody,
  TableCell,
  TableHead,
  TableHeader,
  TableRow,
} from "@/components/ui/table";
import { Badge } from "@/components/ui/badge";
import { Sheet, SheetContent, SheetHeader, SheetTitle } from "@/components/ui/sheet";
import { Label } from "@/components/ui/label";
import { ScrollArea } from "@/components/ui/scroll-area";
import { Separator } from "@/components/ui/separator";
import { Skeleton } from "@/components/ui/skeleton";
import { Slider } from "@/components/ui/slider";
import { AlertTriangle } from "lucide-react";

const WRITING_CRITERIA = ["Task Achievement", "Coherence", "Lexical Resource", "Grammatical Range"];
const SPEAKING_CRITERIA = ["Fluency", "Lexical Resource", "Grammatical Range", "Pronunciation"];

export default function GradingQueue() {
  const { examId: examIdParam } = useParams();
  const examId = Number(examIdParam);
  const { data: queue = [], isLoading } = useGradingQueue({ exam_id: examId });

  const filtered = useMemo(() => {
    if (!Number.isFinite(examId) || examId <= 0) return queue;
    return queue.filter((row) => row.exam_id === examId);
  }, [queue, examId]);

  const [open, setOpen] = useState(false);
  const [active, setActive] = useState<GradingQueueItem | null>(null);
  const skill = active?.skill ?? "writing";
  const attemptId = active?.id ?? 0;

  const responseQ = useStudentResponse(attemptId, skill);
  const rubricQ = useGradingRubric(attemptId, skill);
  const aiSuggest = useAIGradeSuggestion();
  const submitGrade = useSubmitGrade();

  const [scores, setScores] = useState<Record<string, number>>({});

  const criteriaNames = skill === "speaking" ? SPEAKING_CRITERIA : WRITING_CRITERIA;

  const openRow = (row: GradingQueueItem) => {
    setActive(row);
    setScores({});
    setOpen(true);
  };

  useEffect(() => {
    if (!open || !rubricQ.data) return;
    const names = skill === "speaking" ? SPEAKING_CRITERIA : WRITING_CRITERIA;
    const list = rubricQ.data;
    const next: Record<string, number> = {};
    list.forEach((c) => {
      next[c.name] = typeof c.score === "number" ? c.score : 0;
    });
    names.forEach((n) => {
      if (next[n] === undefined) next[n] = 0;
    });
    setScores(next);
  }, [open, rubricQ.data, skill]);

  const handleAISuggest = () => {
    if (!active) return;
    aiSuggest.mutate(
      { attemptId: active.id, skill },
      {
        onSuccess: (data) => {
          setScores((prev) => {
            const next = { ...prev };
            data.criteria_scores.forEach((c) => {
              next[c.name] = c.score;
            });
            return next;
          });
        },
      },
    );
  };

  const handleSubmit = () => {
    if (!active) return;
    submitGrade.mutate(
      {
        attempt_id: active.id,
        skill,
        criteria_scores: criteriaNames.map((name) => ({ name, score: scores[name] ?? 0 })),
      },
      {
        onSuccess: () => {
          setOpen(false);
          setActive(null);
        },
      },
    );
  };

  return (
    <div className="space-y-6 p-6">
      <div>
        <h1 className="text-2xl font-bold">Grading queue</h1>
        <p className="text-muted-foreground">Exam {examIdParam}</p>
      </div>

      <Card>
        <CardHeader>
          <CardTitle>Pending submissions</CardTitle>
        </CardHeader>
        <CardContent>
          {isLoading ? (
            <Skeleton className="h-40 w-full" />
          ) : (
            <Table>
              <TableHeader>
                <TableRow>
                  <TableHead>Student Name</TableHead>
                  <TableHead>Exam Title</TableHead>
                  <TableHead>Skill</TableHead>
                  <TableHead>Submitted At</TableHead>
                  <TableHead>Status</TableHead>
                  <TableHead className="text-right">Action</TableHead>
                </TableRow>
              </TableHeader>
              <TableBody>
                {filtered.map((row) => (
                  <TableRow key={`${row.id}-${row.skill}`}>
                    <TableCell className="font-medium">{row.student_name}</TableCell>
                    <TableCell>{row.exam_title}</TableCell>
                    <TableCell className="capitalize">{row.skill}</TableCell>
                    <TableCell>{new Date(row.submitted_at).toLocaleString()}</TableCell>
                    <TableCell>
                      <Badge variant={row.status === "pending" ? "secondary" : "default"}>{row.status}</Badge>
                    </TableCell>
                    <TableCell className="text-right">
                      <Button type="button" size="sm" onClick={() => openRow(row)}>
                        Grade Now
                      </Button>
                    </TableCell>
                  </TableRow>
                ))}
              </TableBody>
            </Table>
          )}
        </CardContent>
      </Card>

      <Sheet open={open} onOpenChange={setOpen}>
        <SheetContent className="flex w-full flex-col sm:max-w-xl">
          <SheetHeader>
            <SheetTitle>Grade response</SheetTitle>
          </SheetHeader>
          <ScrollArea className="flex-1 pr-4">
            <div className="space-y-6 py-4">
              {responseQ.isLoading ? (
                <Skeleton className="h-32 w-full" />
              ) : responseQ.data ? (
                <div className="space-y-3">
                  <p className="text-sm text-muted-foreground">{responseQ.data.prompt_text}</p>
                  {responseQ.data.type === "writing" && responseQ.data.text ? (
                    <div className="rounded-md border bg-muted/30 p-4 text-sm whitespace-pre-wrap">{responseQ.data.text}</div>
                  ) : null}
                  {responseQ.data.type === "speaking" ? (
                    <div className="rounded-md border border-dashed p-6 text-center text-sm text-muted-foreground">
                      Audio response placeholder
                    </div>
                  ) : null}
                </div>
              ) : null}

              <Separator />

              <div className="space-y-4">
                <h3 className="font-semibold">Rubric</h3>
                {criteriaNames.map((name) => (
                  <div key={name} className="space-y-2">
                    <div className="flex items-center justify-between gap-2">
                      <Label htmlFor={`score-${name}`}>{name}</Label>
                      <span className="text-sm text-muted-foreground">0–9</span>
                    </div>
                    <Slider
                      id={`score-${name}`}
                      min={0}
                      max={9}
                      step={1}
                      value={[scores[name] ?? 0]}
                      onValueChange={(v) => setScores((s) => ({ ...s, [name]: v[0] ?? 0 }))}
                    />
                    <p className="text-sm font-medium">{scores[name] ?? 0}</p>
                  </div>
                ))}
              </div>

              <div className="flex flex-wrap gap-2">
                <Button type="button" variant="secondary" onClick={handleAISuggest} disabled={aiSuggest.isPending || !active}>
                  AI Grade Suggestion
                </Button>
                <Button type="button" onClick={handleSubmit} disabled={submitGrade.isPending || !active}>
                  Submit Grade
                </Button>
              </div>
              {aiSuggest.isError ? (
                <p className="flex items-center gap-2 text-sm text-destructive">
                  <AlertTriangle className="h-4 w-4" />
                  Suggestion could not be loaded.
                </p>
              ) : null}
            </div>
          </ScrollArea>
        </SheetContent>
      </Sheet>
    </div>
  );
}