"use client"

import Link from "next/link"
import { useEffect, useEffectEvent, useState, useTransition } from "react"
import { ArrowLeftIcon, ExternalLinkIcon } from "lucide-react"
import { Button, buttonVariants } from "@/components/ui/button"
import { cn } from "@/lib/utils"
import { saveVariant } from "../../actions/variants"
import type { ShareState } from "../../lib/preview"
import { getTemplate } from "../../lib/registry"
import type { ListItem, TemplateContent } from "../../lib/types"
import { AiPanel } from "../components/editor/ai-panel"
import { BlocksPanel } from "../components/editor/blocks-panel"
import { ContentPanel } from "../components/editor/content-panel"
import { DesignPanel } from "../components/editor/design-panel"
import { PreviewFrame } from "../components/editor/preview-frame"
import { SharePanel } from "../components/editor/share-panel"

export type EditorVariant = {
    id: string
    name: string
    templateKey: string
    clientId: string | null
    content: TemplateContent
    shareToken: string | null
    shareExpiresAt: string | null
    shareState: ShareState
}

const tabs = [
    { key: "content", label: "Inhalte" },
    { key: "design", label: "Design" },
    { key: "ai", label: "KI" },
    { key: "share", label: "Teilen" },
] as const

type Tab = (typeof tabs)[number]["key"]

function snapshot(name: string, clientId: string | null, content: TemplateContent) {
    return JSON.stringify({ name, clientId, content })
}

export function VariantEditor({ variant, clients }: { variant: EditorVariant; clients: { id: string; name: string }[] }) {
    const def = getTemplate(variant.templateKey)
    const [name, setName] = useState(variant.name)
    const [clientId, setClientId] = useState(variant.clientId)
    const [content, setContent] = useState(variant.content)
    const [saved, setSaved] = useState(() => snapshot(variant.name, variant.clientId, variant.content))
    const [tab, setTab] = useState<Tab>("content")
    // Baukasten: Baustein, zu dem die Vorschau springt (n zählt hoch, damit erneutes Aufklappen wieder springt)
    const [focus, setFocus] = useState<{ id: string; n: number } | null>(null)
    const [error, setError] = useState<string | null>(null)
    const [pending, startTransition] = useTransition()

    const current = snapshot(name, clientId, content)
    const dirty = current !== saved

    function save() {
        startTransition(async () => {
            const result = await saveVariant(variant.id, { name, clientId, content })
            if ("error" in result) {
                setError(result.error)
                return
            }
            setError(null)
            setSaved(current)
        })
    }

    const onShortcut = useEffectEvent((event: KeyboardEvent) => {
        if ((event.metaKey || event.ctrlKey) && event.key.toLowerCase() === "s") {
            event.preventDefault()
            if (dirty && !pending) save()
        }
    })

    useEffect(() => {
        window.addEventListener("keydown", onShortcut)
        return () => window.removeEventListener("keydown", onShortcut)
    }, [])

    useEffect(() => {
        if (!dirty) return
        const warn = (event: BeforeUnloadEvent) => event.preventDefault()
        window.addEventListener("beforeunload", warn)
        return () => window.removeEventListener("beforeunload", warn)
    }, [dirty])

    if (!def) return null

    function updateField(section: string, field: string, value: string | ListItem[]) {
        setContent((c) => ({ ...c, data: { ...c.data, [section]: { ...c.data[section], [field]: value } } }))
    }

    return (
        <div className="flex flex-col gap-4 lg:h-[calc(100dvh-4rem)]">
            <div className="flex flex-wrap items-center gap-3">
                <Link
                    href="/admin/templates"
                    aria-label="Zurück zu den Vorlagen"
                    className={buttonVariants({ variant: "ghost", size: "icon-sm" })}
                    onClick={(event) => {
                        if (dirty && !window.confirm("Ungespeicherte Änderungen verwerfen?")) event.preventDefault()
                    }}
                >
                    <ArrowLeftIcon />
                </Link>
                <div className="min-w-0 flex-1">
                    <input
                        value={name}
                        onChange={(event) => setName(event.target.value)}
                        aria-label="Name der Variante"
                        className="w-full truncate rounded-md bg-transparent text-xl font-semibold outline-none focus-visible:ring-2 focus-visible:ring-ring/50 md:text-2xl"
                    />
                    <p className="text-xs text-muted-foreground">Vorlage „{def.name}“ · {def.industry}</p>
                </div>
                <span className={cn("text-xs", dirty ? "text-signal-warning" : "text-muted-foreground")}>
                    {pending ? "Speichert …" : dirty ? "Ungespeicherte Änderungen" : "Gespeichert"}
                </span>
                <a
                    href={`/preview/${def.key}?variant=${variant.id}`}
                    target="_blank"
                    rel="noreferrer"
                    title="Zeigt den gespeicherten Stand"
                    className={buttonVariants({ variant: "outline", size: "sm" })}
                >
                    <ExternalLinkIcon /> Vollbild
                </a>
                <Button size="sm" onClick={save} disabled={!dirty || pending}>
                    Speichern
                </Button>
            </div>
            {error && <p className="text-sm text-destructive">{error}</p>}

            <div className="grid min-h-0 flex-1 gap-4 lg:grid-cols-[minmax(320px,400px)_minmax(0,1fr)]">
                <aside className="flex min-h-0 flex-col overflow-hidden rounded-xl border bg-card">
                    <div role="tablist" className="flex gap-1 border-b p-1.5">
                        {tabs.map((item) => (
                            <button
                                key={item.key}
                                type="button"
                                role="tab"
                                aria-selected={tab === item.key}
                                onClick={() => setTab(item.key)}
                                className={cn(
                                    "flex-1 cursor-pointer rounded-md px-3 py-1.5 text-sm transition-colors",
                                    tab === item.key ? "bg-surface font-medium" : "text-muted-foreground hover:text-foreground"
                                )}
                            >
                                {item.label}
                            </button>
                        ))}
                    </div>
                    <div className="min-h-0 flex-1 overflow-y-auto p-4">
                        {tab === "content" && (
                            <>
                                <ContentPanel def={def} data={content.data} hidden={content.hidden} onChange={updateField} />
                                {def.builder && (
                                    <BlocksPanel
                                        library={def.builder.library}
                                        blocks={content.blocks}
                                        onChange={(blocks) => setContent((c) => ({ ...c, blocks }))}
                                        onFocus={(id) => setFocus((current) => ({ id, n: (current?.n ?? 0) + 1 }))}
                                    />
                                )}
                            </>
                        )}
                        {tab === "design" && (
                            <DesignPanel def={def} content={content} onChange={(patch) => setContent((c) => ({ ...c, ...patch }))} />
                        )}
                        {tab === "ai" && (
                            <AiPanel variantId={variant.id} ai={content.ai} onChange={(patch) => setContent((c) => ({ ...c, ai: { ...c.ai, ...patch } }))} />
                        )}
                        {tab === "share" && (
                            <SharePanel variant={variant} clients={clients} clientId={clientId} onClientChange={setClientId} dirty={dirty} />
                        )}
                    </div>
                </aside>

                <PreviewFrame templateKey={def.key} variantId={variant.id} content={content} focus={focus} />
            </div>
        </div>
    )
}