import type { VmValue } from '@mirascript/mirascript';
import type { EvalExpressionCache, ExpressionCache } from './parser.js';
import { Scope, unwrap } from './scope.js';
import type { Evaluator } from './main.js';

/**
 * 表达式求值
 */
export function evaluateEval<T extends VmValue>(
    evaluator: Evaluator | null,
    expression: EvalExpressionCache,
    scope: Scope,
): T | null {
    try {
        const result = expression.func(scope.proxy);
        if (result == null) return null;
        return unwrap(result as T);
    } catch (error: unknown) {
        if (scope.throws) throw error;
        (evaluator?.logger ?? console).warn(
            `Failed to execute expression "${expression.source}": ${(error as Error).message || String(error)}.`,
            {
                error,
                scope,
            },
        );
        return null;
    }
}

/**
 * 表达式求值
 */
export function evaluate<T extends VmValue>(
    evaluator: Evaluator | null,
    expression: ExpressionCache,
    scope: Scope,
): T | null {
    let ret: T | null = null;
    if (expression.func != null) {
        scope ??= new Scope();
        const reset = scope.reset(evaluator);
        try {
            ret = evaluateEval<T>(evaluator, expression, scope);
        } finally {
            reset();
        }
    } else if (expression.error != null) {
        if (scope.throws) {
            throw expression.error;
        }
    }
    if (ret == null) return null;
    return ret;
}