const Ajv = require("ajv")
const confSchema = require('./configSchema.json')

let  DynamoDBClient, GetItemCommand, marshall, unmarshall

module.exports = class configHelper {

    constructor(options){
        this.config = {}
        if(options.onAws) {
            DynamoDBClient = require("@aws-sdk/client-dynamodb").DynamoDBClient
            GetItemCommand = require("@aws-sdk/client-dynamodb").GetItemCommand
            marshall = require("@aws-sdk/util-dynamodb").marshall
            unmarshall = require("@aws-sdk/util-dynamodb").unmarshall
            this. dynamoClient = new DynamoDBClient({ region: options.awsRegion })

            this.awsTable = options.awsTable
            this.awsServiceName = options.awsServiceName
            this.fetchConfig = this.fetchConfigDynamo
            this.refreshAccessRights = this.refreshAccessRightsDynamo
        } else {
            this.localfile = options.localfile
            this.fetchConfig = this.fetchConfigFile
            this.refreshAccessRights = this.refreshAccessRightsFile
        }
        const ajv = new Ajv({
            allowUnionTypes: true
        })
        this.configValidator = ajv.compile(confSchema)        
    }

    isValidConfig(conf){
        if(this.configValidator(conf)) return(true)
        console.error('Invalid configuration: ', this.configValidator.errors)
        return(false)
    }

    async dynamoGet(subKey = null){
        let params = new GetItemCommand({
            TableName: this.awsTable,
            Key: {
                serviceName: marshall(this.awsServiceName),
            },
          })
        
        let result = await this.dynamoClient.send(params)
        let obj = unmarshall(result.Item)
        if((typeof(subKey)=='string') && (subKey in obj)) return(obj[subKey])
        return(obj)
    }

    async fetchConfigDynamo(){
        let curConfig = this.config
        this.config = await this.dynamoGet()

        if(process.env.UNSECURE)        this.config.server.unsecure = Boolean(process.env.UNSECURE);
        if(process.env.REDIS_HOST)      this.config.redis.host = process.env.REDIS_HOST;
        if(process.env.REDIS_TLS)       this.config.redis.tls = Boolean(process.env.REDIS_TLS);
        if(process.env.REDIS_PORT)      this.config.redis.port = Number(process.env.REDIS_PORT);
        if(process.env.REDIS_USER)      this.config.redis.user = process.env.REDIS_USER;
        if(process.env.REDIS_PASSWORD)  this.config.redis.pass = process.env.REDIS_PASSWORD;
    
        if(this.isValidConfig(this.config)) return(this.config)
        console.error(this.isValidConfig.errors)
        //revert if invalid conf
        this.config = curConfig        
    }

    async fetchConfigFile(){
        let curConfig = this.config
        this.config = await require(this.localfile)
        if(this.isValidConfig(this.config)) return(this.config)
        console.error(this.isValidConfig.errors)
        //revert if invalid conf
        this.config = curConfig
    }

    async refreshAccessRightsDynamo(){
        let ar =  await this.dynamoGet('accessRights')
        this.config.accessRights = ar
    }

    async refreshAccessRightsFile(){
        delete require.cache[require.resolve(this.localfile)]
        let tmp
        try { tmp = require(this.localfile) }
        catch(err) { 
            console.error('Error Reloading config !! (bad json?) => Keeping current accessRights !')
            return 
        }
        if(!tmp.accessRights) {
            console.error('Error Reloading config !! (no accessRights !) => Keeping current accessRights !')
            return           
        }
        this.config.accessRights = tmp.accessRights
    }
}