import { useEffect, useState } from 'react';
import { useNavigate, useParams, useSearchParams } from 'react-router-dom';

import { useAdminTask } from '@/contexts/AdminTaskContext';
import { useDateFormat } from '@/hooks/useDateFormat';
import { PageMeta } from '@/contexts/MetadataContext';

import TasksTable from '../../components/task_list/TasksTable';

import { Button } from '@/components/ui/button';
import { Badge } from '@/components/ui/badge';
import { Skeleton } from '@/components/ui/skeleton';
import { Separator } from '@/components/ui/separator';
import {
    ArrowLeft, Pencil, Users, ListTodo, Info,
    NotebookPen, FileText, CalendarClock,
} from 'lucide-react';

// ─── Helpers ────────────────────────────────────────────────────────────────

function InfoRow({ label, children }) {
    return (
        <div className="flex flex-col gap-0.5">
            <span className="text-xs text-muted-foreground uppercase tracking-wide">{label}</span>
            <span className="text-sm font-medium">{children ?? <span className="text-muted-foreground italic">—</span>}</span>
        </div>
    );
}

function SectionCard({ icon: Icon, title, children }) {
    return (
        <div className="rounded-lg border bg-card p-5 space-y-4">
            <div className="flex items-center gap-2">
                {Icon && <Icon className="h-4 w-4 text-muted-foreground" />}
                <h2 className="text-sm font-semibold">{title}</h2>
            </div>
            <Separator />
            {children}
        </div>
    );
}

function LoadingSkeleton() {
    return (
        <div className="space-y-5">
            <Skeleton className="h-32 w-full" />
            <Skeleton className="h-32 w-full" />
        </div>
    );
}

// ─── Tab: Details ───────────────────────────────────────────────────────────

function DetailsTab({ taskList }) {
    const { fmtDateTime } = useDateFormat();

    if (!taskList) return <LoadingSkeleton />;

    const groups = taskList.groups ?? [];
    const taskCount = taskList.tasks?.length ?? 0;

    return (
        <div className="space-y-5">
            <SectionCard icon={FileText} title="Basic Information">
                <div className="space-y-4">
                    <InfoRow label="Name">{taskList.name}</InfoRow>
                    {taskList.description && (
                        <InfoRow label="Description">
                            <span className="whitespace-pre-wrap text-sm font-normal text-foreground">
                                {taskList.description}
                            </span>
                        </InfoRow>
                    )}
                </div>
            </SectionCard>

            <SectionCard icon={ListTodo} title="Stats">
                <div className="grid grid-cols-2 gap-4">
                    <InfoRow label="Tasks">
                        <div className="flex items-center gap-1.5 mt-0.5">
                            <ListTodo className="h-3.5 w-3.5 text-muted-foreground" />
                            {taskCount}
                        </div>
                    </InfoRow>
                    <InfoRow label="Groups">
                        <div className="flex items-center gap-1.5 mt-0.5">
                            <Users className="h-3.5 w-3.5 text-muted-foreground" />
                            {taskList.group_count ?? groups.length}
                        </div>
                    </InfoRow>
                </div>
            </SectionCard>

            <SectionCard icon={Users} title="Assigned Groups">
                {groups.length > 0 ? (
                    <div className="flex flex-wrap gap-1.5">
                        {groups.map((g) => (
                            <Badge key={g.group_id} variant="secondary">
                                <Users className="size-3 mr-1" />
                                {g.name ?? g.group_id}
                            </Badge>
                        ))}
                    </div>
                ) : (
                    <p className="text-sm text-muted-foreground">No groups assigned.</p>
                )}
            </SectionCard>

            <SectionCard icon={CalendarClock} title="Audit">
                <div className="grid grid-cols-2 gap-4">
                    <InfoRow label="Created At">
                        {taskList.createdAt ? fmtDateTime(taskList.createdAt) : '—'}
                    </InfoRow>
                    <InfoRow label="Updated At">
                        {taskList.updatedAt ? fmtDateTime(taskList.updatedAt) : '—'}
                    </InfoRow>
                </div>
            </SectionCard>
        </div>
    );
}

// ─── Tabs config ────────────────────────────────────────────────────────────

const TABS = [
    { key: 'details', label: 'Details', icon: Info },
    { key: 'tasks', label: 'Tasks', icon: NotebookPen },
];

// ─── Page ───────────────────────────────────────────────────────────────────

export default function ViewTaskList() {
    const navigate = useNavigate();
    const { taskListId } = useParams();
    const [searchParams] = useSearchParams();
    const { fetchTaskList } = useAdminTask();

    const [taskList, setTaskList] = useState(null);
    const [activeTab, setActiveTab] = useState(
        searchParams.get('tab') === 'tasks' ? 'tasks' : 'details'
    );

    useEffect(() => {
        fetchTaskList(taskListId).then((data) => {
            if (!data) return;
            setTaskList(data);
        });
    }, [taskListId]);

    return (
        <div className="flex flex-col min-h-screen bg-muted/60">
            <PageMeta title={taskList ? `${taskList.name} - STARR` : undefined} description={taskList?.description} />

            {/* ── Sticky header ── */}
            <div
                className="sticky z-20 shrink-0 border-b bg-white/70 dark:bg-zinc-900/70 backdrop-blur-md"
                style={{ top: 'var(--navbar-h)' }}
            >
                <div className="lg:container lg:mx-auto lg:px-6 px-4">
                    <div className="flex items-center gap-3 py-3">
                        <Button type="button" variant="ghost" size="icon" onClick={() => navigate('/admin/taskList')}>
                            <ArrowLeft className="h-4 w-4" />
                        </Button>
                        <div className="flex-1 min-w-0">
                            <h1 className="text-xl font-semibold leading-tight flex items-center gap-2">
                                <ListTodo className="h-5 w-5 text-muted-foreground" />
                                View Task List
                            </h1>
                            {taskList && (
                                <p className="text-sm text-muted-foreground">{taskList.name}</p>
                            )}
                        </div>
                        {activeTab === 'details' && (
                            <Button
                                variant="outline"
                                size="sm"
                                onClick={() => navigate(`/admin/taskList/${taskListId}/edit`)}
                                disabled={!taskList}
                            >
                                <Pencil className="h-4 w-4 mr-2" />
                                Edit
                            </Button>
                        )}
                    </div>

                    {/* Underline tabs */}
                    <div className="flex gap-1 pb-0 -mb-px">
                        {TABS.map(({ key, label, icon: Icon }) => (
                            <button
                                key={key}
                                type="button"
                                onClick={() => setActiveTab(key)}
                                className={[
                                    'flex items-center gap-1.5 px-4 py-2.5 text-sm font-medium border-b-2 transition-colors',
                                    activeTab === key
                                        ? 'border-primary text-primary'
                                        : 'border-transparent text-muted-foreground hover:text-foreground',
                                ].join(' ')}
                            >
                                <Icon className="h-3.5 w-3.5" />
                                {label}
                            </button>
                        ))}
                    </div>
                </div>
            </div>

            {/* ── Content ── */}
            <div className="lg:container lg:mx-auto lg:px-6 px-4 py-6">
                <div className={activeTab === 'tasks' ? 'pb-16' : 'max-w-3xl mx-auto pb-16'}>
                    {activeTab === 'details' && <DetailsTab taskList={taskList} />}
                    {activeTab === 'tasks' && <TasksTable taskListId={taskListId} />}
                </div>
            </div>
        </div>
    );
}