/**
 * Vue Composable for Trigo AI Agent
 *
 * Provides reactive interface to the ONNX-based AI agent for move generation.
 * Features:
 * - Lazy initialization (only loads when needed)
 * - Reactive state tracking (ready, thinking, errors)
 * - Automatic cleanup on unmount
 * - Move generation with error handling
 * - Uses tree agent with evaluation mode for efficient parallel move evaluation
 */

import { ref, onUnmounted } from "vue";
import { TrigoTreeAgent } from "@inc/trigoTreeAgent";
import { OnnxInferencer } from "@/services/onnxInferencer";
import type { TrigoGame } from "@inc/trigo/game";
import type { Position } from "@inc/trigo/types";

/**
 * Composable for using the Trigo AI agent in Vue components
 */
export function useTrigoAgent() {
	// Reactive state
	const isReady = ref(false);
	const isThinking = ref(false);
	const error = ref<string | null>(null);
	const lastMoveTime = ref<number>(0);

	// Agent instance (created lazily)
	let agent: TrigoTreeAgent | null = null;
	let inferencer: OnnxInferencer | null = null;

	/**
	 * Initialize the AI agent
	 * - Loads ONNX evaluation model and prepares for inference
	 * - Call this when entering VS AI mode
	 * - Safe to call multiple times (won't re-initialize)
	 */
	const initialize = async (): Promise<void> => {
		if (isReady.value) {
			console.log("[useTrigoAgent] Already initialized");
			return;
		}

		error.value = null;

		try {
			console.log("[useTrigoAgent] Initializing tree agent with evaluation mode...");

			// Create OnnxInferencer with evaluation model
			inferencer = new OnnxInferencer({
				modelPath: "/onnx/GPT2CausalLM_ep0015_evaluation.onnx",
				vocabSize: 259,
				seqLen: 2048 // Evaluation models support longer sequences
			});

			// Initialize ONNX model
			await inferencer.initialize();

			// Create tree agent with the inferencer
			agent = new TrigoTreeAgent(inferencer);

			isReady.value = true;
			console.log("[useTrigoAgent] ✓ Tree agent ready");
		} catch (err) {
			const errorMessage =
				err instanceof Error ? err.message : "Failed to initialize AI agent";
			error.value = errorMessage;
			console.error("[useTrigoAgent] Initialization failed:", err);
			throw err;
		}
	};

	/**
	 * Generate the next move for the AI player
	 *
	 * @param game - Current game instance
	 * @returns The selected move position, or null if no valid moves or pass move
	 * @throws Error if agent is not initialized
	 */
	const generateMove = async (game: TrigoGame): Promise<Position | null> => {
		if (!agent) {
			throw new Error("AI agent not initialized. Call initialize() first.");
		}

		if (!isReady.value) {
			throw new Error("AI agent is not ready yet.");
		}

		if (isThinking.value) {
			console.warn("[useTrigoAgent] Already generating a move, ignoring request");
			return null;
		}

		error.value = null;
		isThinking.value = true;

		try {
			console.log("[useTrigoAgent] Generating move with tree agent...");
			const startTime = performance.now();

			// Use tree agent to select best move
			const move = await agent.selectBestMove(game);

			const elapsed = performance.now() - startTime;
			lastMoveTime.value = elapsed;
			console.log(`[useTrigoAgent] ✓ Move generated in ${elapsed.toFixed(2)}ms`);

			// Convert Move to Position (return null if pass move)
			if (!move || move.isPass) {
				console.log("[useTrigoAgent] AI chose to pass");
				return null;
			}

			if (move.x !== undefined && move.y !== undefined && move.z !== undefined) {
				return { x: move.x, y: move.y, z: move.z };
			}

			console.warn("[useTrigoAgent] Move has undefined coordinates:", move);
			return null;
		} catch (err) {
			const errorMessage = err instanceof Error ? err.message : "Failed to generate move";
			error.value = errorMessage;
			console.error("[useTrigoAgent] Move generation failed:", err);
			throw err;
		} finally {
			isThinking.value = false;
		}
	};

	/**
	 * Check if the agent is initialized and ready
	 */
	const checkIsReady = (): boolean => {
		return agent !== null && inferencer !== null;
	};

	/**
	 * Clean up resources when component unmounts
	 */
	const cleanup = (): void => {
		if (agent || inferencer) {
			console.log("[useTrigoAgent] Cleaning up...");
			agent = null;
			inferencer = null;
			isReady.value = false;
			isThinking.value = false;
			error.value = null;
			lastMoveTime.value = 0;
		}
	};

	// Automatic cleanup on component unmount
	onUnmounted(() => {
		cleanup();
	});

	return {
		// State
		isReady,
		isThinking,
		error,
		lastMoveTime,

		// Methods
		initialize,
		generateMove,
		checkIsReady,
		cleanup
	};
}