import type {bot_event_name, bot_instance_context} from '../../instance/bot_instance_init.ts';
import type {BranchState} from '../../../types/bot/workflow/runtime.ts';
import type {Json, workflow_config} from '../../../types/bot/workflow/workflow.ts';
import type {WorkflowStartTemplate} from '../../../types/bot/workflow/metadata.ts';
import {assert_json, evaluate_condition} from '../runtime/value.ts';
import {normalize_event} from '../node_action/event_node/registry.ts';
import {describe, output} from '../metadata.ts';

export const config_template: WorkflowStartTemplate = {
    name: 'event', version: '1.0.0',
    i18n: describe('事件启动', '机器人出生并就绪后，监听指定事件并按可选条件启动工作流。'),
    config: [
        {name: 'auto_start', type: 'boolean', required: false, default: true,
            i18n: describe('自动监听', '机器人连接并出生后自动监听事件。')},
        {name: 'mode', type: 'select', required: false, default: 'continuous',
            i18n: describe('监听模式', '持续监听，或在一次启动被接受后停止监听。'), options: [
                {value: 'continuous', i18n: describe('持续', '持续接受匹配的事件。')},
                {value: 'once', i18n: describe('一次', '接受一次启动或排队后停止；忙碌跳过时继续监听。')},
            ]},
        {name: 'event', type: 'string', required: true, provider: 'event',
            i18n: describe('事件名称', '选择已描述的事件或填写自定义事件名称；不允许 workflow_update。')},
        {name: 'condition', type: 'condition', required: false,
            i18n: describe('触发条件', '使用标准化后的 trigger 数据判断；支持多个条件全部满足（and/且）、任一满足（or/或）和嵌套分组。条件为真时启动，引用缺失时跳过。')},
    ],
    output: {
        ...output('object', '事件数据', '具体字段由所选事件模板定义；未知事件输出 {event, args}。'),
        properties: {event: output('string', '事件名称', '当前订阅的事件名称。')},
        additional_properties: output('json', '事件字段', '事件适配器提供的有界 JSON 数据。'),
    },
};

export function create_event_handler(definition: workflow_config,
    start: (trigger: Record<string, Json>) => void): (...args: unknown[]) => void {
    if (definition.start.type !== 'event' || definition.start.event === 'workflow_update') {
        throw new Error('Invalid workflow event trigger');
    }
    const config = definition.start;
    return (...args: unknown[]) => {
        if (config.event === 'any' && args[0] === 'workflow_update') return;
        try {
            if (args.length > 32) return;
            const trigger = normalize_event(config.event, args);
            if (!trigger) return;
            assert_json(trigger);
            if (Buffer.byteLength(JSON.stringify(trigger)) > 65_536) return;
            if (config.condition) {
                const state: BranchState = {trigger, vars: structuredClone(definition.initial_vars ?? {}),
                    outputs: {}, last_result: null, inputs: {}, retry_counts: {}};
                if (!evaluate_condition(config.condition, state)) return;
            }
            start(trigger);
        } catch { /* Unsupported payloads and missing condition references skip this occurrence. */ }
    };
}

export function register_event_start(context: Pick<bot_instance_context<any>, 'on' | 'off'>,
    definition: workflow_config, start: (trigger: Record<string, Json>) => void): () => void {
    const callback = create_event_handler(definition, start);
    const event = (definition.start as {event: string}).event as bot_event_name;
    try { context.on(event, callback); }
    catch (error) { context.off(event, callback); throw error; }
    let disposed = false;
    return () => {
        if (disposed) return;
        disposed = true;
        context.off(event, callback);
    };
}