package main

import (
	"encoding/csv"
	"fmt"
	"os"
	"strconv"

	"src.wolkict.net/sepa/pain"
)

// FieldsPerBatchLine are the expected number of fields in each CSV line.
const FieldsPerBatchLine = 9

// ImportIndex keeps track of what column corresponds to what data.
type ImportIndex int

// These are our numbered input fields
const (
	ImportName ImportIndex = iota
	ImportAddr1
	ImportAddr2
	ImportCountry
	ImportIBAN
	ImportMandateId
	ImportSignatureDate
	ImportAmount
	ImportInfo
)

func ImportCSV(fn string) ([]pain.DrctDbtTxInf, error) {
	f, err := os.Open(fn)
	if err != nil {
		return nil, fmt.Errorf("opening file %q failed: %v", fn, err)
	}
	defer f.Close()

	csvReader := csv.NewReader(f)
	csvReader.FieldsPerRecord = FieldsPerBatchLine

	all, err := csvReader.ReadAll()
	if err != nil {
		return nil, fmt.Errorf("reading csv %q failed: %v", fn, err)
	}

	ret := make([]pain.DrctDbtTxInf, len(all))
	for i, line := range all {
		if line[0] == "name" {
			// Header line
			continue
		}

		dbtr := pain.NewDebtor(line[ImportName], line[ImportAddr1], line[ImportAddr2], line[ImportCountry])
		dbtrAcct := pain.NewDbtrAcct(line[ImportIBAN])
		mandateInfo := pain.NewMandateInfo(line[ImportMandateId], line[ImportSignatureDate])
		amount, err := strconv.ParseFloat(line[ImportAmount], 64)
		if err != nil {
			return nil, fmt.Errorf("error importing line %d, cannot parse amount: %v", i, err)
		}

		ret[i] = pain.NewDirectDebitTransaction(dbtr, dbtrAcct, mandateInfo, amount, line[ImportInfo], i)
	}
	return ret, nil
}