class SnapToBus{
    constructor(config){
        this._curBusConfig = []
        this._stagedBusConfig = config // null Means nothing uncommitted
        this.commitConfig()
    }

    get busConfig() { return this._stagedBusConfig }
    get liveBusConfig() { return this._curBusConfig }
    set busConfig(newConfig) { this._stagedBusConfig = newConfig }

    async commitConfig(){
        const chansToAdd = []
        const chansToKeep = []
        console.log('=======>_stagedBusConfig', this._stagedBusConfig)
        for(const chanObj of this._stagedBusConfig){
            console.log('staged chan:',chanObj.chan,' current ones:', this._curBusConfig.map(item => item.chan))
            if(this._curBusConfig.map(item => item.chan).includes(chanObj.chan)) chansToKeep.push(chanObj)
            else chansToAdd.push(chanObj)
        }
        const chansToDel = this._curBusConfig.filter(item => (!chansToKeep.map(c=>c.chan).includes(item.chan) && !chansToAdd.map(c=>c.chan).includes(item.chan)))
        app.MessageBus.subscribe(chansToAdd.map(item => item.chan))
        app.MessageBus.unSubscribe(chansToDel.map(item => item.chan))
        // console.log('subscribe:', chansToAdd.map(item => item.chan))
        // console.log('unSubscribe:', chansToDel)
  
        const eventsToAdd = chansToAdd.flatMap(item => item.events.map(ev => ({ chan:item.chan, eventName:ev.eventName })))
        let eventsToDel = []//= chansToDel.flatMap(item => item.events.map(ev => ({ chan:item.chan, eventName:ev.eventName })))
        for(const oldChan of this._curBusConfig){
            for(const oldEvent of oldChan.events){
                for(const keepChan of chansToKeep){
                    if(!keepChan.events.map(item=>item.eventName).includes(oldEvent.eventName)) eventsToDel.push({chan: oldChan.chan, eventName: oldEvent.eventName})
                }
            }
        }
        
        // console.log('eventsToAdd:', eventsToAdd)
        // console.log('eventsToDel:', eventsToDel)
        for(const eventToAdd of eventsToAdd){
            app.MessageBus.addBusListener(eventToAdd.eventName, [eventToAdd.chan], this.processBus.bind(this), 'snaptobus')
        }
        for(const eventToDel of eventsToDel){
            app.MessageBus.removeBusListener(eventToDel.eventName, this.processBus.bind(this), 'snaptobus')
        }

        this._curBusConfig = this.deepClone(this._stagedBusConfig)
    }
    
    deepClone(obj) { // Needed because structuredClone doesn't take functions (and we have transformers)
        if (obj === null || typeof obj !== 'object') {
            return obj
        }
        if (Array.isArray(obj)) {
            return obj.map((el => this.deepClone(el)))
        }
        const clone = {}
        for (const key in obj) {
            clone[key] = this.deepClone(obj[key])
        }
        return clone
    }
}
const s2bConfig = [
    {   chan: 'gps:agents', // What to subscribe to
        events: [  // What to select on this chan
            {   eventName: 'moving',
                snaps: [
                    {
                        // selector will be used as css selector for a snap element / group, 
                        // with LAST MINUTE template resolving of event properties (with eventual dots)
                        selector: '#${aid}', 
                        assign: {
                            x: 'coords.x',  // type string: event property, eventual dots to go down object
                            y: 'coords.y',
                        },
                        animate: true
                    }
                ]
            },
            {   eventName: 'rotating',
                snaps: [
                    {
                        selector: '#${aid}', 
                        assign: {
                            r: 'rotangle'
                        },
                        animate: true
                    }
                ]
            },            
        ]
    },
    {   chan: 'agent:*', // wildcards allowed
        events: [
            {   eventName: 'aging',
                snaps: [
                    {
                        selector: '#{aid}',
                        assign: {
                            fill: { // transformer function
                                arguments: [ 'age' ], // What to give from the event as function's params
                                transformer: i => `rgb(${Math.round(255 * i / 10)},0,${Math.round(255 * (1 - i / 10))})`
                            },
                        },
                    }
                ]
            },
        ]
    },
]

t = new SnapToBus(s2bConfig)
console.log('----------------------------------------')
t.busConfig.splice(1, 1) 
t.busConfig[0].events.splice(1, 1)
t.commitConfig()