import { useMemo } from "react";
import { useNavigate, useParams } from "react-router-dom";
import { Button } from "@/components/ui/button";
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card";
import { Tabs, TabsContent, TabsList, TabsTrigger } from "@/components/ui/tabs";
import { Table, TableBody, TableCell, TableHead, TableHeader, TableRow } from "@/components/ui/table";
import { Badge } from "@/components/ui/badge";
import { ScrollArea } from "@/components/ui/scroll-area";
import { Skeleton } from "@/components/ui/skeleton";
import { useIeltsSkills } from "@/hooks/queries/useExamTemplates";
import type { IELTSPartConfig, IELTSSkill, IELTSSkillConfig } from "@/types";

const SKILL_LABEL: Record<IELTSSkill, string> = {
  listening: "Listening",
  reading: "Reading",
  writing: "Writing",
  speaking: "Speaking",
};

const STATIC_PARTS: Record<IELTSSkill, Omit<IELTSPartConfig, "part_number">[]> = {
  listening: [
    { question_count: 10, content_type: "Audio + MCQ", time_limit_min: 7, description: "Part 1 — everyday social" },
    { question_count: 10, content_type: "Audio + MCQ", time_limit_min: 7, description: "Part 2 — monologue" },
    { question_count: 10, content_type: "Audio + MCQ", time_limit_min: 8, description: "Part 3 — conversation" },
    { question_count: 10, content_type: "Audio + MCQ", time_limit_min: 8, description: "Part 4 — lecture" },
  ],
  reading: [
    { question_count: 13, content_type: "Passage + items", time_limit_min: 20, description: "Passage 1" },
    { question_count: 13, content_type: "Passage + items", time_limit_min: 20, description: "Passage 2" },
    { question_count: 14, content_type: "Passage + items", time_limit_min: 20, description: "Passage 3" },
  ],
  writing: [
    { question_count: 1, content_type: "Task response", time_limit_min: 20, description: "Task 1" },
    { question_count: 1, content_type: "Essay", time_limit_min: 40, description: "Task 2" },
  ],
  speaking: [
    { question_count: 1, content_type: "Interview", time_limit_min: 5, description: "Part 1 — introduction" },
    { question_count: 1, content_type: "Long turn", time_limit_min: 4, description: "Part 2 — cue card" },
    { question_count: 1, content_type: "Discussion", time_limit_min: 5, description: "Part 3 — abstract" },
  ],
};

function resolveParts(skill: IELTSSkill, cfg?: IELTSSkillConfig): IELTSPartConfig[] {
  const fromApi = cfg?.parts?.length ? cfg.parts : [];
  if (fromApi.length) return fromApi;
  return STATIC_PARTS[skill].map((p, i) => ({
    part_number: i + 1,
    ...p,
  }));
}

function requiredQuestions(skill: IELTSSkill, parts: IELTSPartConfig[]): number {
  const sum = parts.reduce((a, p) => a + p.question_count, 0);
  if (sum > 0) return sum;
  if (skill === "listening") return 40;
  if (skill === "reading") return 40;
  if (skill === "writing") return 2;
  return 3;
}

export default function IeltsSkillConfig() {
  const { examId: examIdParam } = useParams<{ examId: string }>();
  const navigate = useNavigate();
  const examId = Number(examIdParam);
  const { data, isLoading, isError } = useIeltsSkills(Number.isFinite(examId) ? examId : 0);

  const skills = useMemo(() => {
    if (!data) return [] as IELTSSkillConfig[];
    const arr = Array.isArray(data) ? data : (data as { data?: IELTSSkillConfig[] }).data ?? [];
    return arr;
  }, [data]);

  const defaultTab = (skills.length > 0 ? skills[0]?.skill : "listening") ?? "listening";

  if (!Number.isFinite(examId) || examId <= 0) {
    return <p className="p-6 text-destructive">Invalid exam.</p>;
  }

  if (isLoading) {
    return (
      <div className="p-6 max-w-6xl mx-auto space-y-4">
        <Skeleton className="h-10 w-64" />
        <Skeleton className="h-96 w-full" />
      </div>
    );
  }

  const displaySkills: IELTSSkillConfig[] = skills.length > 0
    ? skills
    : (["listening", "reading", "writing", "speaking"] as IELTSSkill[]).map((s) => ({
        skill: s,
        parts: STATIC_PARTS[s].map((p, i) => ({ part_number: i + 1, ...p })),
        available_count: 0,
      }));

  return (
    <div className="p-6 max-w-6xl mx-auto">
      <div className="flex flex-col gap-6 lg:flex-row">
        <div className="flex-1 space-y-4 min-w-0">
          <div>
            <h1 className="text-2xl font-semibold tracking-tight">Skill layout</h1>
            <p className="text-muted-foreground mt-1">Review the official structure before choosing content.</p>
          </div>

          <Tabs defaultValue={defaultTab} className="w-full">
            <TabsList className="flex flex-wrap h-auto gap-1">
              {displaySkills.map((s) => (
                <TabsTrigger key={s.skill} value={s.skill} className="capitalize">
                  {SKILL_LABEL[s.skill]}
                </TabsTrigger>
              ))}
            </TabsList>
            {displaySkills.map((s) => {
              const parts = resolveParts(s.skill, s);
              const required = requiredQuestions(s.skill, parts);
              const pool = s.available_count ?? 0;
              const pct = required > 0 ? Math.min(100, Math.round((pool / required) * 100)) : 0;
              return (
                <TabsContent key={s.skill} value={s.skill} className="space-y-4">
                  <Card>
                    <CardHeader className="flex flex-row items-start justify-between gap-4">
                      <div>
                        <CardTitle className="capitalize">{SKILL_LABEL[s.skill]}</CardTitle>
                        <CardDescription>
                          Read-only structure. Pool coverage: {pool} items available for ~{required} required questions.
                        </CardDescription>
                      </div>
                      <Badge variant={pct >= 100 ? "default" : "secondary"}>{pct}% pool coverage</Badge>
                    </CardHeader>
                    <CardContent>
                      <Table>
                        <TableHeader>
                          <TableRow>
                            <TableHead>Part</TableHead>
                            <TableHead>Questions</TableHead>
                            <TableHead>Content type</TableHead>
                            <TableHead>Time (min)</TableHead>
                            <TableHead className="text-right">Pool</TableHead>
                            <TableHead className="text-right w-[140px]" />
                          </TableRow>
                        </TableHeader>
                        <TableBody>
                          {parts.map((p) => (
                            <TableRow key={`${s.skill}-${p.part_number}`}>
                              <TableCell className="font-medium">{p.part_number}</TableCell>
                              <TableCell>{p.question_count}</TableCell>
                              <TableCell>{p.content_type}</TableCell>
                              <TableCell>{p.time_limit_min}</TableCell>
                              <TableCell className="text-right text-muted-foreground">
                                {Math.max(0, Math.floor(pool / parts.length))}
                              </TableCell>
                              <TableCell className="text-right">
                                <Button
                                  size="sm"
                                  type="button"
                                  onClick={() =>
                                    navigate(
                                      `/admin/exam/ielts/${examId}/content?skill=${s.skill}&part=${p.part_number}`,
                                    )
                                  }
                                >
                                  Configure content
                                </Button>
                              </TableCell>
                            </TableRow>
                          ))}
                        </TableBody>
                      </Table>
                    </CardContent>
                  </Card>
                </TabsContent>
              );
            })}
          </Tabs>
        </div>

        <aside className="w-full lg:w-80 shrink-0 space-y-3">
          <Card>
            <CardHeader>
              <CardTitle className="text-base">Completion</CardTitle>
              <CardDescription>Per-skill readiness for assembly.</CardDescription>
            </CardHeader>
            <CardContent className="space-y-3">
              <ScrollArea className="h-[min(420px,50vh)]">
                {displaySkills.map((s) => {
                  const parts = resolveParts(s.skill, s);
                  const required = requiredQuestions(s.skill, parts);
                  const pool = s.available_count ?? 0;
                  const ok = pool >= required;
                  return (
                    <div
                      key={s.skill}
                      className="flex items-center justify-between gap-2 rounded-md border p-3 mb-2 text-sm"
                    >
                      <span className="capitalize font-medium">{SKILL_LABEL[s.skill]}</span>
                      <Badge variant={ok ? "default" : "outline"}>{ok ? "Ready" : "Needs content"}</Badge>
                    </div>
                  );
                })}
              </ScrollArea>
              <Button className="w-full" type="button" onClick={() => navigate(`/admin/exam/ielts/${examId}/validate`)}>
                Continue to validation
              </Button>
            </CardContent>
          </Card>
        </aside>
      </div>
    </div>
  );
}