/**
 * Public shape of the `shake` operation, kept in a dependency-free leaf module
 * so slash-command registries and controllers can import `formatShakeSummary`
 * without pulling in the heavy `agent-session` module graph (which would form
 * an import cycle through the slash-command registry).
 */

/** Mode selector for `AgentSession.shake`. */
export type ShakeMode = "elide" | "images" | "thinking";

/** Outcome of an `AgentSession.shake` run. */
export interface ShakeResult {
	mode: ShakeMode;
	/** Whole tool-call results dropped. */
	toolResultsDropped: number;
	/** Large fenced/XML blocks dropped. */
	blocksDropped: number;
	/** Image blocks removed (images mode only). */
	imagesDropped?: number;
	/** Thinking blocks dropped (thinking mode only). */
	thinkingBlocksDropped?: number;
	/** Thinking blocks the provider replays from its payload, left in place (thinking mode only). */
	thinkingBlocksKept?: number;
	/** Estimated context tokens reclaimed. */
	tokensFreed: number;
	/** Session artifact holding the dropped originals, when persisted. */
	artifactId?: string;
}

/** One-line operator summary of a {@link ShakeResult} (shared by TUI + ACP). */
export function formatShakeSummary(result: ShakeResult): string {
	if (result.mode === "images") {
		const n = result.imagesDropped ?? 0;
		return n === 0
			? "No images found in this session."
			: `Dropped ${n} image${n === 1 ? "" : "s"} from this session.`;
	}
	if (result.mode === "thinking") {
		const dropped = result.thinkingBlocksDropped ?? 0;
		const kept = result.thinkingBlocksKept ?? 0;
		if (dropped === 0 && kept === 0) return "No thinking blocks found in this session.";
		const keptText = `${kept} thinking block${kept === 1 ? "" : "s"} ${kept === 1 ? "was" : "were"} kept because removing ${
			kept === 1 ? "it" : "them"
		} would not change what the model receives`;
		if (dropped === 0) return `${keptText}.`;
		const droppedText = `Dropped ${dropped} thinking block${dropped === 1 ? "" : "s"} from this session${result.tokensFreed > 0 ? ` (~${result.tokensFreed} tokens freed)` : ""}`;
		return kept === 0 ? `${droppedText}.` : `${droppedText}; ${keptText}.`;
	}
	const parts: string[] = [];
	if (result.toolResultsDropped > 0) {
		parts.push(`${result.toolResultsDropped} tool result${result.toolResultsDropped === 1 ? "" : "s"}`);
	}
	if (result.blocksDropped > 0) {
		parts.push(`${result.blocksDropped} block${result.blocksDropped === 1 ? "" : "s"}`);
	}
	if (parts.length === 0) return "Nothing to shake.";
	return `Shook ${parts.join(" + ")} (~${result.tokensFreed} tokens freed).`;
}