import { useMemo, useState } from "react";
import { useParams } from "react-router-dom";
import { useQueryClient } from "@tanstack/react-query";
import {
  Headphones,
  Mic,
  BookMarked,
  PenLine,
  CheckCircle2,
  CircleDot,
  Lock,
  ClipboardCheck,
  Award,
} from "lucide-react";
import { Button } from "@/components/ui/button";
import { Card, CardContent, CardDescription, CardHeader, CardTitle } from "@/components/ui/card";
import { Progress } from "@/components/ui/progress";
import { Dialog, DialogContent, DialogFooter, DialogHeader, DialogTitle } from "@/components/ui/dialog";
import { Input } from "@/components/ui/input";
import { Label } from "@/components/ui/label";
import { Separator } from "@/components/ui/separator";
import { useAiCourse, useAiCourseTracks, useCreateIeltsCourse } from "@/hooks/queries/useAiCourse";
import { queryKeys } from "@/hooks/queries/keys";
import type { AICourseTrack, AIGenerationStep, AITrackModule } from "@/types";
import {
  BarChart,
  Bar,
  XAxis,
  YAxis,
  CartesianGrid,
  Tooltip,
  ResponsiveContainer,
  LineChart,
  Line,
} from "recharts";
import { toast } from "sonner";

const SKILL_ICONS = [PenLine, BookMarked, Mic, Headphones];

export default function AiIeltsCourse() {
  const { courseId: cid } = useParams<{ courseId: string }>();
  const courseId = Number(cid);
  const qc = useQueryClient();
  const { data: course, isLoading } = useAiCourse(Number.isFinite(courseId) ? courseId : undefined);
  const { data: tracksRaw } = useAiCourseTracks(Number.isFinite(courseId) ? courseId : undefined);
  const createIelts = useCreateIeltsCourse();

  const [targetBand, setTargetBand] = useState("");
  const [readinessOpen, setReadinessOpen] = useState(false);

  const skillsRanked =
    course?.skills_ranked_by_gap && course.skills_ranked_by_gap.length > 0
      ? course.skills_ranked_by_gap
      : [
          { skill: "Writing", gap: 1.2 },
          { skill: "Speaking", gap: 0.9 },
          { skill: "Reading", gap: 0.4 },
          { skill: "Listening", gap: 0.3 },
        ];

  const weakTypes = course?.weak_question_types ?? {
    Writing: ["Task 2 argument depth"],
    Reading: ["True/False/Not Given"],
    Speaking: ["Part 2 long turn"],
    Listening: ["Form completion"],
  };

  const skillPanels: { skill: string; steps: AIGenerationStep[]; progress_percent: number }[] =
    course?.ielts_generation_by_skill?.length
      ? course.ielts_generation_by_skill
      : ["Writing", "Reading", "Speaking", "Listening"].map((skill, i) => ({
          skill,
          steps: [
            { name: "Blueprint", status: i === 0 ? ("in_progress" as const) : ("pending" as const) },
            { name: "Items", status: "pending" as const },
            { name: "Rubric alignment", status: "pending" as const },
          ],
          progress_percent: [35, 20, 10, 5][i] ?? 0,
        }));

  const tracks: AICourseTrack[] = useMemo(() => {
    if (tracksRaw?.length) return tracksRaw;
    return ["Writing", "Reading", "Speaking", "Listening"].map((name, ti) => ({
      name: `${name} skill`,
      progress_percent: 15 + ti * 8,
      modules: ieltsModules(name),
    }));
  }, [tracksRaw]);

  const bandSeries = [
    { label: "L", v: course?.current_bands?.Listening ?? 6.0 },
    { label: "R", v: course?.current_bands?.Reading ?? 6.5 },
    { label: "W", v: course?.current_bands?.Writing ?? 5.5 },
    { label: "S", v: course?.current_bands?.Speaking ?? 6.0 },
  ];

  if (isLoading) {
    return <div className="flex justify-center py-24 text-muted-foreground">Loading…</div>;
  }

  const tgt = targetBand || String(course?.target_level ?? "6.5");

  return (
    <div className="space-y-8 p-6 max-w-7xl mx-auto">
      <div className="flex flex-col gap-2 md:flex-row md:items-center md:justify-between">
        <div>
          <h1 className="text-2xl font-semibold tracking-tight">AI IELTS course</h1>
          <p className="text-muted-foreground text-sm">Band-focused practice generated for you</p>
        </div>
        <Button variant="secondary" size="sm" onClick={() => setReadinessOpen(true)}>
          <ClipboardCheck className="h-4 w-4 mr-2" />
          Practice exam readiness
        </Button>
      </div>

      <Card>
        <CardHeader>
          <CardTitle>IELTS gap profile</CardTitle>
          <CardDescription>Exam context and targets</CardDescription>
        </CardHeader>
        <CardContent className="grid gap-4 md:grid-cols-2 lg:grid-cols-4">
          <div>
            <Label className="text-muted-foreground">Exam type</Label>
            <p className="text-lg font-semibold mt-1">{course?.exam_type ?? "Academic"}</p>
          </div>
          <div>
            <Label className="text-muted-foreground">Current bands</Label>
            <p className="text-sm mt-1">
              {Object.entries(course?.current_bands ?? { L: 6, R: 6.5, W: 5.5, S: 6 })
                .map(([k, v]) => `${k}: ${v}`)
                .join(" · ")}
            </p>
          </div>
          <div className="space-y-2">
            <Label htmlFor="tgt">Target band</Label>
            <Input id="tgt" value={tgt} onChange={(e) => setTargetBand(e.target.value)} />
          </div>
          <div>
            <Label className="text-muted-foreground">Ranked by gap</Label>
            <ol className="mt-2 text-sm list-decimal list-inside space-y-1">
              {skillsRanked.map((s) => (
                <li key={s.skill}>
                  {s.skill} (Δ {s.gap.toFixed(1)})
                </li>
              ))}
            </ol>
          </div>
        </CardContent>
        <CardContent className="pt-0 space-y-3">
          <Label className="text-muted-foreground">Weak question types</Label>
          <div className="grid sm:grid-cols-2 gap-3 text-sm">
            {Object.entries(weakTypes).map(([skill, items]) => (
              <div key={skill} className="rounded-md border p-3">
                <div className="font-medium mb-1">{skill}</div>
                <ul className="list-disc list-inside text-muted-foreground">
                  {items.map((x) => (
                    <li key={x}>{x}</li>
                  ))}
                </ul>
              </div>
            ))}
          </div>
          <Button
            disabled={createIelts.isPending}
            onClick={() => {
              const band = Number(targetBand || course?.target_level || 7);
              createIelts.mutate(
                {
                  skill: skillsRanked[0]?.skill ?? "writing",
                  target_band: Number.isFinite(band) ? band : 7,
                },
                {
                  onSuccess: () => {
                    qc.invalidateQueries({ queryKey: queryKeys.aiCourse.course(courseId) });
                    qc.invalidateQueries({ queryKey: queryKeys.aiCourse.tracks(courseId) });
                    toast.success("AI IELTS course started.");
                  },
                  onError: (e) => toast.error(e instanceof Error ? e.message : "Could not start"),
                },
              );
            }}
          >
            Start AI IELTS Course
          </Button>
        </CardContent>
      </Card>

      <div>
        <h2 className="text-lg font-semibold mb-4">Per-skill generation</h2>
        <div className="grid gap-4 md:grid-cols-2 xl:grid-cols-4">
          {skillPanels.map((panel, idx) => {
            const Icon = SKILL_ICONS[idx % SKILL_ICONS.length];
            return (
              <Card key={panel.skill}>
                <CardHeader className="pb-2">
                  <CardTitle className="text-base flex items-center gap-2">
                    <Icon className="h-4 w-4" />
                    {panel.skill}
                  </CardTitle>
                  <CardDescription>{panel.progress_percent}%</CardDescription>
                </CardHeader>
                <CardContent className="space-y-2">
                  <Progress value={panel.progress_percent} />
                  <ul className="text-sm space-y-1">
                    {panel.steps.map((s) => (
                      <li key={s.name} className="flex justify-between gap-2">
                        <span>{s.name}</span>
                        <span className="text-muted-foreground capitalize">{s.status.replace("_", " ")}</span>
                      </li>
                    ))}
                  </ul>
                </CardContent>
              </Card>
            );
          })}
        </div>
      </div>

      <div>
        <h2 className="text-lg font-semibold mb-4">Skill columns</h2>
        <div className="grid gap-4 lg:grid-cols-4">
          {tracks.map((track) => (
            <Card key={track.name}>
              <CardHeader className="pb-2">
                <CardTitle className="text-sm">{track.name}</CardTitle>
                <CardDescription>{track.progress_percent}%</CardDescription>
              </CardHeader>
              <CardContent className="space-y-2">
                <Progress value={track.progress_percent} />
                <Separator />
                <ul className="space-y-2 text-sm">
                  {track.modules.map((m) => (
                    <li key={m.id} className="flex gap-2">
                      <ModIcon st={m.status} />
                      <span>{m.title}</span>
                    </li>
                  ))}
                </ul>
              </CardContent>
            </Card>
          ))}
        </div>
      </div>

      <Card>
        <CardHeader>
          <CardTitle className="flex items-center gap-2">
            <Award className="h-5 w-5" />
            Band improvement report
          </CardTitle>
          <CardDescription>Current skill snapshot vs trajectory</CardDescription>
        </CardHeader>
        <CardContent className="grid gap-8 lg:grid-cols-2">
          <div className="h-56">
            <ResponsiveContainer width="100%" height="100%">
              <BarChart data={bandSeries}>
                <CartesianGrid strokeDasharray="3 3" className="stroke-muted" />
                <XAxis dataKey="label" />
                <YAxis domain={[0, 9]} />
                <Tooltip />
                <Bar dataKey="v" fill="hsl(var(--primary))" radius={[4, 4, 0, 0]} />
              </BarChart>
            </ResponsiveContainer>
          </div>
          <div className="h-56">
            <ResponsiveContainer width="100%" height="100%">
              <LineChart
                data={[
                  { w: 1, b: 5.6 },
                  { w: 2, b: 6.1 },
                  { w: 3, b: 6.4 },
                  { w: 4, b: 6.8 },
                ]}
              >
                <CartesianGrid strokeDasharray="3 3" className="stroke-muted" />
                <XAxis dataKey="w" />
                <YAxis domain={[5, 8]} />
                <Tooltip />
                <Line type="monotone" dataKey="b" stroke="hsl(var(--primary))" strokeWidth={2} dot />
              </LineChart>
            </ResponsiveContainer>
          </div>
        </CardContent>
      </Card>

      <Dialog open={readinessOpen} onOpenChange={setReadinessOpen}>
        <DialogContent>
          <DialogHeader>
            <DialogTitle>Practice exam readiness</DialogTitle>
          </DialogHeader>
          <p className="text-sm text-muted-foreground">
            When each skill column reaches the practice threshold, you unlock a full timed paper with authentic pacing and
            AI feedback.
          </p>
          <DialogFooter>
            <Button onClick={() => setReadinessOpen(false)}>Got it</Button>
          </DialogFooter>
        </DialogContent>
      </Dialog>
    </div>
  );
}

function ModIcon({ st }: { st: AITrackModule["status"] }) {
  if (st === "completed") return <CheckCircle2 className="h-4 w-4 text-green-600 shrink-0" />;
  if (st === "in_progress") return <CircleDot className="h-4 w-4 text-primary shrink-0" />;
  return <Lock className="h-4 w-4 text-muted-foreground shrink-0" />;
}

function ieltsModules(skill: string): AITrackModule[] {
  return [
    { id: 1, title: `${skill} — Drill set A`, status: "completed", estimated_hours: 2 },
    { id: 2, title: `${skill} — Drill set B`, status: "in_progress", estimated_hours: 2 },
    { id: 3, title: `${skill} — Exam-style pack`, status: "locked", estimated_hours: 3 },
  ];
}