import {Context} from "./context";
import {Command} from "../utils/command";
import {effect} from "@preact/signals-core";

export type RuleContext<T> = Context & {
    actions: Command[];
    handledActions: number;
    invocations: RuleContext<unknown>[];
    resolution?: T;
}

/**
 * 调用规则生成器并管理其上下文
 * @param pushContext - 用于推送上下文到上下文栈的函数
 * @param type - 规则类型
 * @param rule - 规则生成器函数
 * @returns 规则执行结果
 */
export function invokeRuleContext<T>(
    pushContext: (context: Context) => void,
    type: string,
    rule: Generator<string, T, Command>
): RuleContext<T> {
    const ctx: RuleContext<T> = {
        type,
        actions: [],
        handledActions: 0,
        invocations: [],
        resolution: undefined,
    };

    let disposed = false;

    const executeRule = () => {
        if (disposed || ctx.resolution !== undefined) return;

        try {
            const result = rule.next();

            if (result.done) {
                ctx.resolution = result.value;
                return;
            }

            const actionType = result.value;

            if (actionType) {
                // 暂停于 yield 点，等待外部处理动作
                // 当外部更新 actions 后，effect 会重新触发
            }
        } catch (error) {
            throw error;
        }
    };

    const dispose = effect(() => {
        if (ctx.resolution !== undefined) {
            dispose();
            disposed = true;
            return;
        }
        executeRule();
    });

    pushContext(ctx);

    return ctx;
}

/**
 * 创建一个规则生成器辅助函数
 * @param type - 规则类型
 * @param fn - 规则逻辑函数
 */
export function createRule<T>(
    type: string,
    fn: (ctx: RuleContext<T>) => Generator<string, T, Command>
): (ctx: RuleContext<T>) => Generator<string, T, Command> {
    return fn;
}