import {saveAs} from './filesaver'

// build and return csv string from array of column values

const toCsvString = stringArr =>

stringArr.reduce(

(accumulated, val, idx) =>

(accumulated += `"${

typeof val === 'object' ? JSON.stringify(val).replace(/"/g, '""') : val

}"${idx < stringArr.length - 1 ? ',' : ''}`),

''

)

const jsonToCSV = records => {

const columns = []

// get list of all columns across all records (as some record lists contain mixed structures)

records.forEach(rec => {

const newKeys = Object.keys(rec).filter(

key => columns.indexOf(key) === -1 && typeof rec[key] !== 'function'

)

if (newKeys.length > 0) {

columns.push(...newKeys)

}

})

// map col name to col idx

const colToIdx = columns.reduce((accumulated, curCol, curIdx) => {

accumulated[curCol] = curIdx

return accumulated

}, {})

const numCols = columns.length

const headerCsv = toCsvString(columns)

return records.reduce((csvStr, curRec) => {

const row = new Array(numCols)

row.fill('')

Object.keys(curRec).forEach(key => (row[colToIdx[key]] = curRec[key]))

csvStr = `${csvStr}\n${toCsvString(row)}`

return csvStr

}, headerCsv)

}

const exportCSV = records => {

const csvData = jsonToCSV(records)

const autoByteOrderMark = true

saveAs(

new Blob(['\ufeff', csvData], {type: 'text/csv;charset=utf-8'}),

'pi-blockexplorer-export.csv',

autoByteOrderMark

)

}

export {exportCSV, jsonToCSV}