"use client";

import {
  Activity,
  AlertCircle,
  ArrowLeft,
  Clock,
  ExternalLink,
  FileText,
  Globe,
  MessageSquare,
  User,
} from "lucide-react";
import Link from "next/link";
import { useParams, useRouter } from "next/navigation";
import { useSession } from "next-auth/react";
import { useEffect, useState } from "react";
import { Badge } from "@/components/ui/badge";
import { Button } from "@/components/ui/button";
import { Card, CardContent, CardHeader, CardTitle } from "@/components/ui/card";
import { formatCategory } from "@/lib/format-enums";
import MessageViewer from "../../../../components/MessageViewer";
import SessionDetails from "../../../../components/SessionDetails";
import type { ChatSession } from "../../../../lib/types";

/**
 * Custom hook for managing session data fetching and state
 */
function useSessionData(id: string | undefined, authStatus: string) {
  const [session, setSession] = useState<ChatSession | null>(null);
  const [loading, setLoading] = useState(true);
  const [error, setError] = useState<string | null>(null);
  const router = useRouter();

  useEffect(() => {
    if (authStatus === "unauthenticated") {
      router.push("/login");
      return;
    }

    if (authStatus === "authenticated" && id) {
      const fetchSession = async () => {
        setLoading(true);
        setError(null);
        try {
          const response = await fetch(`/api/dashboard/session/${id}`);
          if (!response.ok) {
            const errorData = await response.json();
            throw new Error(
              errorData.error ||
                `Failed to fetch session: ${response.statusText}`
            );
          }
          const data = await response.json();
          setSession(data.session);
        } catch (err) {
          setError(
            err instanceof Error ? err.message : "An unknown error occurred"
          );
          setSession(null);
        } finally {
          setLoading(false);
        }
      };
      fetchSession();
    } else if (authStatus === "authenticated" && !id) {
      setError("Session ID is missing.");
      setLoading(false);
    }
  }, [id, authStatus, router]);

  return { session, loading, error };
}

/**
 * Component for rendering loading state
 */
function LoadingCard({ message }: { message: string }) {
  return (
    <div className="space-y-6">
      <Card>
        <CardContent className="pt-6">
          <div className="text-center py-8 text-muted-foreground">
            {message}
          </div>
        </CardContent>
      </Card>
    </div>
  );
}

/**
 * Component for rendering error state
 */
function ErrorCard({ error }: { error: string }) {
  return (
    <div className="space-y-6">
      <Card>
        <CardContent className="pt-6">
          <div className="text-center py-8">
            <AlertCircle className="h-12 w-12 text-destructive mx-auto mb-4" />
            <p className="text-destructive text-lg mb-4">Error: {error}</p>
            <Link href="/dashboard/sessions">
              <Button variant="outline" className="gap-2">
                <ArrowLeft className="h-4 w-4" />
                Back to Sessions List
              </Button>
            </Link>
          </div>
        </CardContent>
      </Card>
    </div>
  );
}

/**
 * Component for rendering session not found state
 */
function SessionNotFoundCard() {
  return (
    <div className="space-y-6">
      <Card>
        <CardContent className="pt-6">
          <div className="text-center py-8">
            <MessageSquare className="h-12 w-12 text-muted-foreground mx-auto mb-4" />
            <p className="text-muted-foreground text-lg mb-4">
              Session not found.
            </p>
            <Link href="/dashboard/sessions">
              <Button variant="outline" className="gap-2">
                <ArrowLeft className="h-4 w-4" />
                Back to Sessions List
              </Button>
            </Link>
          </div>
        </CardContent>
      </Card>
    </div>
  );
}

/**
 * Component for rendering session header with navigation and badges
 */
function SessionHeader({ session }: { session: ChatSession }) {
  return (
    <Card>
      <CardContent className="pt-6">
        <div className="flex flex-col sm:flex-row justify-between items-start sm:items-center gap-4">
          <div className="space-y-2">
            <Link href="/dashboard/sessions">
              <Button
                variant="ghost"
                className="gap-2 p-0 h-auto focus:outline-none focus:ring-2 focus:ring-primary focus:ring-offset-2"
                aria-label="Return to sessions list"
              >
                <ArrowLeft className="h-4 w-4" aria-hidden="true" />
                Back to Sessions List
              </Button>
            </Link>
            <div className="space-y-2">
              <h1 className="text-3xl font-bold">Session Details</h1>
              <div className="flex items-center gap-3">
                <Badge variant="outline" className="font-mono text-xs">
                  ID
                </Badge>
                <code className="text-sm text-muted-foreground font-mono">
                  {(session.sessionId || session.id).slice(0, 8)}...
                </code>
              </div>
            </div>
          </div>
          <div className="flex flex-wrap gap-2">
            {session.category && (
              <Badge variant="secondary" className="gap-1">
                <Activity className="h-3 w-3" />
                {formatCategory(session.category)}
              </Badge>
            )}
            {session.language && (
              <Badge variant="outline" className="gap-1">
                <Globe className="h-3 w-3" />
                {session.language.toUpperCase()}
              </Badge>
            )}
            {session.sentiment && (
              <Badge
                variant={
                  session.sentiment === "positive"
                    ? "default"
                    : session.sentiment === "negative"
                      ? "destructive"
                      : "secondary"
                }
                className="gap-1"
              >
                {session.sentiment.charAt(0).toUpperCase() +
                  session.sentiment.slice(1)}
              </Badge>
            )}
          </div>
        </div>
      </CardContent>
    </Card>
  );
}

/**
 * Component for rendering session overview cards
 */
function SessionOverview({ session }: { session: ChatSession }) {
  return (
    <div className="grid grid-cols-1 md:grid-cols-2 lg:grid-cols-4 gap-4">
      <Card>
        <CardContent className="pt-6">
          <div className="flex items-center gap-3">
            <Clock className="h-8 w-8 text-blue-500" />
            <div>
              <p className="text-sm text-muted-foreground">Start Time</p>
              <p className="font-semibold">
                {new Date(session.startTime).toLocaleString()}
              </p>
            </div>
          </div>
        </CardContent>
      </Card>

      <Card>
        <CardContent className="pt-6">
          <div className="flex items-center gap-3">
            <MessageSquare className="h-8 w-8 text-green-500" />
            <div>
              <p className="text-sm text-muted-foreground">Messages</p>
              <p className="font-semibold">{session.messages?.length || 0}</p>
            </div>
          </div>
        </CardContent>
      </Card>

      <Card>
        <CardContent className="pt-6">
          <div className="flex items-center gap-3">
            <User className="h-8 w-8 text-purple-500" />
            <div>
              <p className="text-sm text-muted-foreground">User ID</p>
              <p className="font-semibold truncate">
                {session.userId || "N/A"}
              </p>
            </div>
          </div>
        </CardContent>
      </Card>

      <Card>
        <CardContent className="pt-6">
          <div className="flex items-center gap-3">
            <Activity className="h-8 w-8 text-orange-500" />
            <div>
              <p className="text-sm text-muted-foreground">Duration</p>
              <p className="font-semibold">
                {session.endTime && session.startTime
                  ? `${Math.round(
                      (new Date(session.endTime).getTime() -
                        new Date(session.startTime).getTime()) /
                        60000
                    )} min`
                  : "N/A"}
              </p>
            </div>
          </div>
        </CardContent>
      </Card>
    </div>
  );
}

export default function SessionViewPage() {
  const params = useParams();
  const { status } = useSession();
  const id = params?.id as string;
  const { session, loading, error } = useSessionData(id, status);

  if (status === "loading") {
    return <LoadingCard message="Loading session..." />;
  }

  if (status === "unauthenticated") {
    return <LoadingCard message="Redirecting to login..." />;
  }

  if (loading && status === "authenticated") {
    return <LoadingCard message="Loading session details..." />;
  }

  if (error) {
    return <ErrorCard error={error} />;
  }

  if (!session) {
    return <SessionNotFoundCard />;
  }

  return (
    <div className="space-y-6 max-w-6xl mx-auto">
      <SessionHeader session={session} />
      <SessionOverview session={session} />

      {/* Session Details */}
      <SessionDetails session={session} />

      {/* Messages */}
      {session.messages && session.messages.length > 0 && (
        <Card>
          <CardHeader>
            <CardTitle className="flex items-center gap-2">
              <MessageSquare className="h-5 w-5" />
              Conversation ({session.messages.length} messages)
            </CardTitle>
          </CardHeader>
          <CardContent>
            <MessageViewer messages={session.messages} />
          </CardContent>
        </Card>
      )}

      {/* Transcript URL */}
      {session.fullTranscriptUrl && (
        <Card>
          <CardHeader>
            <CardTitle className="flex items-center gap-2">
              <FileText className="h-5 w-5" />
              Source Transcript
            </CardTitle>
          </CardHeader>
          <CardContent>
            <a
              href={session.fullTranscriptUrl}
              target="_blank"
              rel="noopener noreferrer"
              className="inline-flex items-center gap-2 text-primary hover:underline focus:outline-none focus:ring-2 focus:ring-primary focus:ring-offset-2 rounded-sm"
              aria-label="Open original transcript in new tab"
            >
              <ExternalLink className="h-4 w-4" aria-hidden="true" />
              View Original Transcript
            </a>
          </CardContent>
        </Card>
      )}
    </div>
  );
}