/**
 * Prompt Saver Extension
 *
 * Saves the current editor text when Ctrl+C clears the input,
 * so accidentally discarded prompts can be retrieved with the up arrow.
 *
 * - Ctrl+C: saves the current text before clearing the editor
 * - Up arrow: if editor is empty and a saved prompt exists, restores it
 * - Subsequent up arrow presses go through normal history as usual
 */

import { CustomEditor, type ExtensionAPI } from "@earendil-works/pi-coding-agent";
import { matchesKey, Key } from "@earendil-works/pi-tui";

// Module-level state: the most recently cleared prompt
let savedPrompt: string | null = null;

class PromptSaverEditor extends CustomEditor {
	handleInput(data: string): void {
		// Intercept Ctrl+C: save the current text before it gets cleared
		if (matchesKey(data, Key.ctrl("c"))) {
			const text = this.getText();
			if (text) {
				savedPrompt = text;
			}
			// Let the default handler clear the editor (or copy if there's a selection)
			super.handleInput(data);
			return;
		}

		// Intercept Up arrow: restore saved prompt if editor is empty
		if (matchesKey(data, Key.up)) {
			if (!this.getText() && savedPrompt) {
				this.setText(savedPrompt);
				savedPrompt = null;
				return; // Don't pass to super — we handled it
			}
			// Editor has text or no saved prompt: normal up behavior (cursor up / history)
		}

		// Pass everything else to the default editor behavior
		super.handleInput(data);
	}
}

export default function (pi: ExtensionAPI) {
	pi.on("session_start", (_event, ctx) => {
		// Only install in TUI mode (not print/json/rpc)
		if (ctx.mode !== "tui") return;

		ctx.ui.setEditorComponent((tui, theme, kb) => new PromptSaverEditor(tui, theme, kb));
	});
}