"use client";

import { useEffect, useState } from "react";
import { createPortal } from "react-dom";

/** The impact read's shape (GET /api/graph/nodes/[id], node interlude):
 *  counts of what full death would take with it, plus the referencing
 *  session/source ids — the CLIENT joins display names from its
 *  snapshot (chats map + imported-notes file paths). */
export interface NodeImpact {
	edges: number;
	quizEvents: number;
	observations: number;
	sessions: string[];
}

/** Join an id to its display name: chat titles from the snapshot's
 *  sessions map, imported-notes paths from fileSources; an unknown id
 *  renders honestly as itself. Exported pure for render pins. */
export function sessionNameOf(
	id: string,
	sessions: Record<string, string>,
	fileSources: Record<string, string>,
): string {
	return sessions[id] ?? fileSources[id] ?? id;
}

/** The 409 extraction_running line (owner phrasing, node interlude):
 *  the server's error names the extraction; the ACTIVITY DOCK is the
 *  surface the user actually watches drain. Exported pure for pins. */
export const EXTRACTION_RETRY_LINE = "An extraction is running — try again when the activity dock drains.";

/** The fact line for one count — honest plurals, no theater ("0 edges"
 *  reads plainly; hiding a zero fact would understate the blast). */
export function countLine(n: number, one: string, many: string): string {
	return `${n} ${n === 1 ? one : many}`;
}

/**
 * Node deletion (node interlude, Platform's 50bfcba engine) — the
 * confirm surface, portaled z-50 like the session-delete dialog whose
 * tone it follows. FULL DEATH by owner ruling: the node, every edge
 * touching it, every quiz/observation event naming it, its mapping
 * lines, its position. The impact facts render plainly so the user
 * weighs the blast radius; "this cannot be undone" says the permanence.
 *
 * The 409 extraction_running gets the dock phrasing (the server's
 * honest line names the extraction; the ACTIVITY DOCK is the surface
 * the user actually watches drain) with a Try-again — the run is never
 * aborted server-side, it clears on its own. The 404 (deleted elsewhere
 * meanwhile) states it plainly and closes into the same refresh: the
 * next snapshot read tells the truth.
 */
/** The dialog's pure body — exported for SSR pins (the settings-dialog
 *  body pattern). The wrapper owns state + effects + the portal. */
export function DeleteNodeBody({
	node,
	joins,
	impact,
	busy,
	failure,
	onClose,
	onRun,
}: {
	node: { id: string; name: string };
	joins: { sessions: Record<string, string>; fileSources: Record<string, string> };
	impact: NodeImpact | "loading" | "gone";
	busy: boolean;
	failure: { code: string; error: string } | null;
	onClose: () => void;
	onRun: () => void;
}) {
	return (
		<div
			role="dialog"
			aria-modal="true"
			aria-label="Delete topic"
			data-testid="delete-node-dialog"
			onClick={(e) => e.stopPropagation()}
			className="w-[32rem] max-w-[calc(100vw-2rem)] rounded-xl border bg-card p-5 shadow-xl"
		>
			<h2 className="font-title text-2xl tracking-tight">Delete “{node.name}”?</h2>
			{impact === "loading" && (
				<p className="mt-2 text-sm text-muted-foreground" data-testid="node-impact-loading">
					Reading what this would remove…
				</p>
			)}
			{impact === "gone" && (
				<div className="mt-2">
					<p className="text-sm text-muted-foreground">
						This topic is no longer in the graph — it was already removed elsewhere.
					</p>
					<div className="mt-4 flex justify-end">
						<button
							type="button"
							data-testid="node-delete-vanished-close"
							onClick={onClose}
							className="rounded-sm px-3 py-1.5 text-xs text-muted-foreground transition-colors hover:text-foreground"
						>
							Close
						</button>
					</div>
				</div>
			)}
			{typeof impact === "object" && (
				<>
					<p className="mt-2 text-sm text-muted-foreground">
						This permanently removes the topic and everything attached to it — this cannot be undone:
					</p>
					<ul
						data-testid="node-impact-facts"
						className="mt-3 space-y-1 rounded-lg border border-border/60 px-4 py-3 text-sm"
					>
						<li>{countLine(impact.edges, "link to another topic", "links to other topics")}</li>
						<li>{countLine(impact.quizEvents, "quiz answer", "quiz answers")}</li>
						<li>{countLine(impact.observations, "session note", "session notes")}</li>
						<li className="text-muted-foreground">
							Referenced by{" "}
							{impact.sessions.length === 0
								? "no session"
								: impact.sessions
										.map((id) => sessionNameOf(id, joins.sessions, joins.fileSources))
										.join(", ")}
						</li>
					</ul>
					{failure && (
						<div
							role="alert"
							data-testid="node-delete-failure"
							className="mt-3 rounded-sm border border-border/60 px-3 py-2 text-xs"
						>
							<span className="text-foreground">
								{failure.code === "extraction_running" ? EXTRACTION_RETRY_LINE : failure.error}
							</span>
							<button
								type="button"
								data-testid="node-delete-retry"
								onClick={onRun}
								disabled={busy}
								className="ml-3 text-xs text-foreground underline-offset-2 hover:underline disabled:opacity-40"
							>
								Try again
							</button>
						</div>
					)}
					<div className="mt-4 flex justify-end gap-2">
						<button
							type="button"
							data-testid="node-delete-cancel"
							onClick={onClose}
							disabled={busy}
							className="rounded-sm px-3 py-1.5 text-xs text-muted-foreground transition-colors hover:text-foreground disabled:opacity-40"
						>
							Cancel
						</button>
						<button
							type="button"
							data-testid="node-delete-confirm"
							onClick={onRun}
							disabled={busy}
							className="rounded-sm border border-border/60 px-3 py-1.5 text-xs text-foreground transition-colors hover:bg-accent disabled:opacity-40"
						>
							{busy ? "Deleting…" : "Delete"}
						</button>
					</div>
				</>
			)}
		</div>
	);
}

export function DeleteNodeDialog({
	node,
	joins,
	onClose,
	onDeleted,
}: {
	/** The node up for deletion; null = closed. Name from the client's
	 *  snapshot (what the user sees on the canvas is what the dialog
	 *  names). */
	node: { id: string; name: string } | null;
	joins: { sessions: Record<string, string>; fileSources: Record<string, string> };
	onClose: () => void;
	/** Success path — the graph view dispatches lh:graph-revision so the
	 *  snapshot refetches (node, edges, label vanish; clusters shrink or
	 *  unrender below the server's minimum). graphRevision rides the
	 *  event; 0 when the response carried none (a vanished node). */
	onDeleted: (nodeId: string, graphRevision: number) => void;
}) {
	const [impact, setImpact] = useState<NodeImpact | "loading" | "gone">("loading");
	const [busy, setBusy] = useState(false);
	const [failure, setFailure] = useState<{ code: string; error: string } | null>(null);

	// Fresh state per node: closing resets; opening another node refetches.
	useEffect(() => {
		if (!node) {
			setImpact("loading");
			setBusy(false);
			setFailure(null);
		}
	}, [node]);

	// The pre-flight impact read — for the dialog the user just opened.
	useEffect(() => {
		if (!node) return;
		let cancelled = false;
		setImpact("loading");
		setFailure(null);
		(async () => {
			try {
				const res = await fetch(`/api/graph/nodes/${encodeURIComponent(node.id)}`);
				if (cancelled) return;
				if (res.status === 404) {
					setImpact("gone");
					return;
				}
				if (!res.ok) throw new Error(String(res.status));
				setImpact((await res.json()) as NodeImpact);
			} catch {
				if (!cancelled) setImpact("gone"); // honest fallback, no facts invented
			}
		})();
		return () => {
			cancelled = true;
		};
	}, [node]);

	// Esc closes (claimed — a dialog Esc must not also abort a turn).
	useEffect(() => {
		if (!node) return;
		const onKeyDown = (e: KeyboardEvent) => {
			if (e.key === "Escape") {
				e.stopPropagation();
				onClose();
			}
		};
		window.addEventListener("keydown", onKeyDown);
		return () => window.removeEventListener("keydown", onKeyDown);
	}, [node, onClose]);

	const run = async () => {
		if (!node || busy) return;
		setBusy(true);
		setFailure(null);
		try {
			const res = await fetch(`/api/graph/nodes/${encodeURIComponent(node.id)}`, { method: "DELETE" });
			const body = (await res.json()) as {
				error?: string;
				code?: string;
				graphRevision?: number;
			};
			if (!res.ok) {
				setFailure({ code: body.code ?? "error", error: body.error ?? `Delete failed (${res.status})` });
				setBusy(false);
				return;
			}
			onDeleted(node.id, body.graphRevision ?? 0);
		} catch {
			setFailure({ code: "network", error: "Delete failed — network error. Try again." });
			setBusy(false);
		}
	};

	if (!node) return null;

	return createPortal(
		<div
			className="fixed inset-0 z-50 flex items-center justify-center bg-background/80"
			onClick={() => {
				if (!busy) onClose();
			}}
		>
			<DeleteNodeBody
				node={node}
				joins={joins}
				impact={impact}
				busy={busy}
				failure={failure}
				onClose={onClose}
				onRun={() => void run()}
			/>
		</div>,
		document.body,
	);
}