import { useEffect, useMemo, useState } from "react";
import { useNavigate } from "react-router-dom";
import { House, Pencil, Bell, Lock, Send, Clock3, Plus, Trash2 } from "lucide-react";
import { Button }    from "@/components/ui/button";
import { Badge }     from "@/components/ui/badge";
import { Spinner }   from "@/components/ui/spinner";
import { Separator } from "@/components/ui/separator";
import {
    AlertDialog, AlertDialogAction, AlertDialogCancel,
    AlertDialogContent, AlertDialogDescription,
    AlertDialogFooter, AlertDialogHeader, AlertDialogTitle,
} from "@/components/ui/alert-dialog";
import AppBreadcrumb from "@/components/generic/Breadcrumb/AppBreadcrumb";
import { PageMeta }  from "@/contexts/MetadataContext";
import {
    AdminNotificationTemplateProvider,
    useAdminNotificationTemplates,
} from "@/contexts/AdminNotificationTemplateContext";
import { NOTIFICATION_TEMPLATE_TYPES, getNotificationTemplateType } from "@/data/notificationTemplateTypes.data";
import { STATUS_META, hasPendingChanges } from "@/data/notificationTemplateStatus.data";
import { cn } from "@/lib/utils";

function TemplateCard({ item, onEdit, onDelete }) {
    const typeMeta = getNotificationTemplateType(item.notify_type);
    const TypeIcon = typeMeta?.icon ?? Bell;
    const status   = STATUS_META[item.status] ?? STATUS_META.draft;
    const pending  = hasPendingChanges(item);

    return (
        <div className="rounded-lg border bg-card p-5 flex flex-col gap-4 h-full">
            <div className="flex items-start justify-between gap-2">
                <div className="w-10 h-10 rounded-lg border bg-muted flex items-center justify-center shrink-0">
                    <TypeIcon className="h-4.5 w-4.5 text-muted-foreground" />
                </div>
                <div className="flex items-center gap-0.5">
                    {!item.is_system && (
                        <Button type="button" variant="ghost" size="icon" className="text-destructive hover:text-destructive" onClick={() => onDelete(item)}>
                            <Trash2 className="h-4 w-4" />
                        </Button>
                    )}
                    <Button type="button" variant="ghost" size="icon" onClick={() => onEdit(item)}>
                        <Pencil className="h-4 w-4" />
                    </Button>
                </div>
            </div>

            <div className="min-w-0 flex-1">
                <div className="flex items-center gap-2 flex-wrap mb-1">
                    <p className="text-sm font-semibold truncate">{item.label}</p>
                    {item.is_system && (
                        <Badge variant="secondary" className="gap-1 shrink-0">
                            <Lock className="h-2.5 w-2.5" /> System
                        </Badge>
                    )}
                </div>
                <code className="text-[10px] bg-muted px-1.5 py-0.5 rounded text-muted-foreground">{item.type}</code>
                <p className="text-xs text-muted-foreground mt-2 line-clamp-2">
                    <span className="text-foreground">{item.title || item.draft_title || "No title yet"}</span>
                </p>
            </div>

            <div className="flex items-center gap-1.5 flex-wrap">
                {typeMeta && (
                    <Badge variant="outline" className="gap-1 text-[11px]">
                        <typeMeta.icon className="h-3 w-3" /> {typeMeta.label}
                    </Badge>
                )}
                <Badge variant="outline" className={cn("gap-1 text-[11px]", status.badgeClass)}>
                    <Send className="h-3 w-3" /> {status.label}
                </Badge>
                {pending && (
                    <Badge variant="outline" className="gap-1 text-[11px] bg-amber-100 text-amber-700 border-amber-400 dark:bg-amber-900/40 dark:text-amber-400 dark:border-amber-700">
                        <Clock3 className="h-3 w-3" /> Pending changes
                    </Badge>
                )}
            </div>
        </div>
    );
}

function NotificationTemplatesInner() {
    const navigate = useNavigate();
    const { templates, loading, fetchTemplates, deleteTemplate } = useAdminNotificationTemplates();
    const [activeType, setActiveType] = useState("all");
    const [deleteTarget, setDeleteTarget] = useState(null);

    useEffect(() => { fetchTemplates(); }, []);

    const handleDelete = async () => {
        if (!deleteTarget) return;
        await deleteTemplate(deleteTarget.notification_template_id);
        setDeleteTarget(null);
    };

    const filtered = useMemo(
        () => activeType === "all" ? templates : templates.filter((t) => t.notify_type === activeType),
        [templates, activeType]
    );

    const typesInUse = useMemo(
        () => NOTIFICATION_TEMPLATE_TYPES.filter((t) => templates.some((tpl) => tpl.notify_type === t.value)),
        [templates]
    );

    return (
        <section className="bg-muted/60 min-h-full">
            <PageMeta title="Announcement Templates - STARR" />
            <div className="lg:container lg:mx-auto lg:px-0 flex flex-col items-start px-4 py-10">
                <div className="w-full max-w-6xl mx-auto">

                    <div className="flex flex-col gap-2 mb-6">
                        <AppBreadcrumb items={[
                            { label: "Home", icon: <House className="size-4" />, to: "/admin" },
                            { label: "Announcements", to: "/admin/announcements" },
                            { label: "Templates" },
                        ]} />
                    </div>

                    <div className="flex items-center justify-between mb-6">
                        <div>
                            <h1 className="text-xl font-semibold">Announcement Templates</h1>
                            <p className="text-sm text-muted-foreground mt-0.5">
                                Title and message wording for every automated notification STARR sends.
                            </p>
                            <div className="flex items-center gap-3 mt-2 text-xs text-muted-foreground">
                                <span className="flex items-center gap-1">
                                    <Send className="h-3 w-3 text-emerald-600" />
                                    {templates.filter((t) => t.status === "sent").length} sent
                                </span>
                                <span className="flex items-center gap-1">
                                    <Pencil className="h-3 w-3" />
                                    {templates.filter((t) => t.status === "draft").length} draft
                                </span>
                                {templates.some(hasPendingChanges) && (
                                    <span className="flex items-center gap-1 text-amber-600">
                                        <Clock3 className="h-3 w-3" />
                                        {templates.filter(hasPendingChanges).length} with pending changes
                                    </span>
                                )}
                            </div>
                        </div>

                        <Button type="button" onClick={() => navigate("/admin/announcement-templates/add")} className="gap-1.5">
                            <Plus className="h-4 w-4" /> Add Template
                        </Button>
                    </div>

                    <div className="rounded-lg border bg-card p-4 flex items-start gap-3 mb-5">
                        <Lock className="h-4 w-4 text-muted-foreground mt-0.5 shrink-0" />
                        <div className="text-xs text-muted-foreground space-y-1">
                            <p>
                                <strong>System</strong> templates are locked — code fires them by referencing their exact
                                type, so only the title and message wording is editable, never the type itself, and they
                                can't be deleted.
                            </p>
                            <p>
                                <strong>Custom</strong> templates (no lock icon) are reusable title/message presets you
                                create — pick one from the "Load from template" dropdown when composing a new announcement
                                to skip retyping recurring wording. You can freely create, edit, and delete these.
                            </p>
                            <p>
                                <strong>Draft vs. Sent</strong> (system templates only): a <strong>Sent</strong> template
                                is the version actually used for real notifications right now. Editing a Sent template
                                doesn't change what goes out immediately — it's held as a pending change until you press{" "}
                                <strong>Publish</strong> again.
                            </p>
                        </div>
                    </div>

                    <div className="flex flex-wrap items-center gap-2 mb-5">
                        <Button
                            type="button" size="sm" variant={activeType === "all" ? "secondary" : "outline"}
                            onClick={() => setActiveType("all")}
                        >
                            All ({templates.length})
                        </Button>
                        {typesInUse.map((t) => {
                            const Icon = t.icon;
                            const count = templates.filter((tpl) => tpl.notify_type === t.value).length;
                            return (
                                <Button
                                    key={t.value}
                                    type="button" size="sm"
                                    variant={activeType === t.value ? "secondary" : "outline"}
                                    onClick={() => setActiveType(t.value)}
                                    className="gap-1.5"
                                >
                                    <Icon className="h-3.5 w-3.5" /> {t.label} ({count})
                                </Button>
                            );
                        })}
                    </div>

                    <Separator className="mb-5" />

                    {loading && !templates.length ? (
                        <div className="flex justify-center py-12"><Spinner className="h-5 w-5" /></div>
                    ) : !filtered.length ? (
                        <p className="text-sm text-muted-foreground text-center py-12">No notification templates found.</p>
                    ) : (
                        <div className="grid grid-cols-1 sm:grid-cols-2 lg:grid-cols-3 gap-4">
                            {filtered.map((item) => (
                                <TemplateCard
                                    key={item.notification_template_id}
                                    item={item}
                                    onEdit={(t) => navigate(`/admin/announcement-templates/${t.notification_template_id}/edit`)}
                                    onDelete={setDeleteTarget}
                                />
                            ))}
                        </div>
                    )}
                </div>
            </div>

            <AlertDialog open={!!deleteTarget} onOpenChange={(open) => !open && setDeleteTarget(null)}>
                <AlertDialogContent>
                    <AlertDialogHeader>
                        <AlertDialogTitle>Delete this template?</AlertDialogTitle>
                        <AlertDialogDescription>
                            "{deleteTarget?.label}" will be permanently removed. It won't affect any announcements already sent.
                        </AlertDialogDescription>
                    </AlertDialogHeader>
                    <AlertDialogFooter>
                        <AlertDialogCancel>Cancel</AlertDialogCancel>
                        <AlertDialogAction onClick={handleDelete} disabled={loading} className="bg-destructive text-destructive-foreground hover:bg-destructive/90">
                            {loading ? <Spinner className="h-4 w-4 mr-2" /> : <Trash2 className="h-4 w-4 mr-2" />}
                            Delete
                        </AlertDialogAction>
                    </AlertDialogFooter>
                </AlertDialogContent>
            </AlertDialog>
        </section>
    );
}

export default function NotificationTemplates() {
    return (
        <AdminNotificationTemplateProvider>
            <NotificationTemplatesInner />
        </AdminNotificationTemplateProvider>
    );
}