import Nodule from '../Nodule.js'

class JoinNodule extends Nodule {
  constructor (props) {
    super(props)
    this._assignProps(props)
  }

  export = () => {
    const baseTable = this.tables.find(t => t.label === this.baseTableLabel)
    const baseTableRows = baseTable.export()
    const tablesToJoin = this.tables.filter(t => {
      return t.label !== this.baseTableLabel
    })

    const relatedTables = this.joinParams.map(joinParam => {
      const foreignTable = tablesToJoin.find(t => {
        return t.label === joinParam.foreignTable
      })
      const foreignTableRows = foreignTable.export()

      const mergedRows = baseTableRows.map(baseRow => {
        const matchingForeignRow = foreignTableRows.find(foreignRow => {
          return baseRow[joinParam.primaryTableKey] === foreignRow[joinParam.matchingKey]
        })
        let rowToMerge = {}
        for (let key in matchingForeignRow) {
          rowToMerge[`${joinParam.foreignTable}::${key}`] = matchingForeignRow[key]
        }
        
        return {...baseRow, ...rowToMerge}
      })
      return mergedRows
    })

    return relatedTables[0]
  }

  setJoinBy = joinBy => {
    const joinByValidation = this._validateJoinBy(joinBy)
    if (joinByValidation.status === 'ERR') throw joinByValidation
    else {
      this.baseTableLabel = joinBy.baseTableLabel
      this.joinParams = joinBy.joinParams
    }
  }

  _assignProps = props => {
    if (props.joinBy) this.setJoinBy(props.joinBy)
  }

  _validateJoinBy = joinBy => {
    const err = {
      status: 'ERR',
      error: {
        label: 'JoinBy Parameters are not valid',
        messages: []
      }
    }
    
    const { baseTableLabel, joinParams } = joinBy
    
    if (!baseTableLabel) err.error.messages.push('No baseTableLabel provided')
    
    if (!Array.isArray(joinParams)) {
      const joinParamsType = typeof joinParams
      err.error.messages.push(`Keys was of type ${joinParamsType} should be an array`)
      return err
    }

    for (let p = 0; p < joinParams.length; p++) {
      if (typeof joinParams[p] !== 'object') err.error.messages.push(`joinParams[${p}] is not an object`)
    }

    if (err.error.messages.length > 0) return err
    else return { status: 'OK' }
  }
}

export default JoinNodule