"use client";

import { useState, useMemo } from "react";
import Link from "next/link";
import { PageHeader } from "@/components/page-header";
import { Card, CardContent } from "@/components/ui/card";
import { Badge } from "@/components/ui/badge";
import { cn } from "@/lib/utils";
import { ChevronRight, Clock, MapPin } from "lucide-react";
import { PlayAudioButton } from "@/app/(app)/transcriptions/[slug]/play-audio-button";

type TranscriptionItem = {
  slug: string;
  name: string;
  type: string;
  date: string | null;
  year: number | null;
  month: number | null;
  day: number | null;
  place: string | null;
  context: string | null;
  reference: string | null;
  durationMinutes: number | null;
  participants: string[];
  audioUrl: string | null;
};

const MONTH_NAMES = [
  "",
  "January",
  "February",
  "March",
  "April",
  "May",
  "June",
  "July",
  "August",
  "September",
  "October",
  "November",
  "December",
];

function MonthSection({
  label,
  items,
  defaultOpen,
}: {
  month: number;
  label: string;
  items: TranscriptionItem[];
  defaultOpen: boolean;
}) {
  const [open, setOpen] = useState(defaultOpen);

  return (
    <div>
      <button
        onClick={() => setOpen(!open)}
        className="flex items-center gap-3 w-full px-5 py-3 text-left hover:bg-muted/50 transition-colors"
      >
        <ChevronRight
          className={cn(
            "size-4 text-muted-foreground shrink-0 transition-transform",
            open && "rotate-90",
          )}
        />
        <span className="font-semibold text-foreground text-sm">{label}</span>
        <span className="text-xs text-muted-foreground tabular-nums">
          {items.length}{" "}
          {items.length === 1 ? "transcription" : "transcriptions"}
        </span>
      </button>

      {open && (
        <ul className="divide-y divide-border">
          {items.map((t) => (
            <li key={t.slug}>
              <Link
                href={`/transcriptions/${t.slug}`}
                className="flex items-center px-5 pl-12 py-3.5 gap-3 hover:bg-muted transition-colors"
              >
                <div className="min-w-0 flex-1">
                  <div className="flex items-center gap-2 flex-wrap">
                    <p className="font-medium text-foreground text-sm">
                      {t.name}
                    </p>
                    <Badge
                      variant={t.type === "lecture" ? "default" : "secondary"}
                      className="text-[10px] px-1.5 py-0"
                    >
                      {t.type === "lecture" ? "Lecture" : "Conversation"}
                    </Badge>
                  </div>
                  <div className="flex items-center gap-3 mt-1 text-xs text-muted-foreground">
                    {t.place && (
                      <span className="flex items-center gap-1">
                        <MapPin className="size-3" />
                        {t.place}
                      </span>
                    )}
                    {t.reference && (
                      <span className="text-primary/70">{t.reference}</span>
                    )}
                    {t.durationMinutes && t.durationMinutes > 0 && (
                      <span className="flex items-center gap-1">
                        <Clock className="size-3" />
                        {t.durationMinutes} min
                      </span>
                    )}
                  </div>
                </div>
                {t.audioUrl && (
                  <PlayAudioButton
                    audioUrl={t.audioUrl}
                    title={t.name}
                    subtitle={[t.date, t.place].filter(Boolean).join(" · ")}
                    sourceUrl={`/transcriptions/${t.slug}`}
                    type={t.type}
                    variant="compact"
                  />
                )}
              </Link>
            </li>
          ))}
        </ul>
      )}
    </div>
  );
}

export function TranscriptionYearBrowser({
  transcriptions,
  year,
  totalCount,
}: {
  transcriptions: TranscriptionItem[];
  year: number;
  totalCount: number;
}) {
  const monthGroups = useMemo(() => {
    const map = new Map<number, TranscriptionItem[]>();
    for (const t of transcriptions) {
      const m = t.month && t.month >= 1 && t.month <= 12 ? t.month : 0;
      if (!map.has(m)) map.set(m, []);
      map.get(m)!.push(t);
    }
    const groups: {
      month: number;
      label: string;
      items: TranscriptionItem[];
    }[] = [];
    for (let m = 1; m <= 12; m++) {
      const items = map.get(m);
      if (items && items.length > 0) {
        groups.push({ month: m, label: MONTH_NAMES[m], items });
      }
    }
    const unknown = map.get(0);
    if (unknown && unknown.length > 0) {
      groups.push({ month: 0, label: "Unknown Month", items: unknown });
    }
    return groups;
  }, [transcriptions]);

  const lectureCount = transcriptions.filter(
    (t) => t.type === "lecture",
  ).length;
  const conversationCount = transcriptions.filter(
    (t) => t.type === "conversation",
  ).length;

  return (
    <>
      <PageHeader sticky>
        <Link
          href="/transcriptions"
          className="text-sm text-muted-foreground hover:text-foreground transition-colors"
        >
          &larr; Transcriptions
        </Link>
        <h1 className="mt-3 text-2xl font-bold text-foreground">
          Transcriptions from {year}
        </h1>
        <p className="mt-1 text-sm text-muted-foreground">
          {totalCount} transcriptions · {lectureCount} lectures ·{" "}
          {conversationCount} conversations
        </p>
      </PageHeader>

      <main className="max-w-5xl mx-auto px-6 py-8 space-y-6">
        {monthGroups.length === 0 ? (
          <div className="py-12 text-center text-muted-foreground">
            <p className="text-lg font-medium">
              No transcriptions for this year
            </p>
          </div>
        ) : (
          <Card className="overflow-hidden">
            <CardContent className="p-0 divide-y divide-border">
              {monthGroups.map((mg, i) => (
                <MonthSection
                  key={mg.month}
                  month={mg.month}
                  label={mg.label}
                  items={mg.items}
                  defaultOpen={i === 0 || monthGroups.length <= 3}
                />
              ))}
            </CardContent>
          </Card>
        )}
      </main>
    </>
  );
}