SFM-loan-Rest-Api/payIn-AAA.go

package main

import (
	log "github.com/sirupsen/logrus"
	"strconv"
	"strings"
	"time"
)

/* Sample Text

AAA Financial Trail Report
Super Finance Markets Pty Ltd
   Loan Number                  SettDate      Loan          Balance    Arrears   DisDate   IntTrail$    Comments
                                             Facility
  Columbus
  Period Servicing: Feb 2020
400053440                       02-Sep-19        $552,463      552,579.52                     $32.19
400063271                        19-Feb-20       $832,000      832,000.00                      $0.00
                                                                       Columbus Total:         $32.19

                                                                            Grand Total:       $32.19

Super Finance Markets Pty Ltd

*/

type PayInAAARow struct {
	LoanNumber string
	Settlement time.Time
	LoanAmount float64
	Balance    float64
	InTrail    float64
}

type PayInAAAPeriod struct {
	Period time.Time
	Rows   []PayInAAARow
}

func (m *AiDecodeIncome) decodeAAAPdf(raw string) (e error) {
	m.AAA = make([]PayInAAAPeriod, 0, 10)
	lines := strings.Split(raw, "\n")

	currentDecoder := PayInAAAPeriod{}
	state := "start"
	for _, l := range lines { // DFA, wow, finally it's used. after years of learning
		switch state {
		case "start":
			state = currentDecoder.processStart(l)
			if state == "LookingForPeriod" {
				// determine column index, if their column is changing
			}
			break
		case "LookingForPeriod":
			state = currentDecoder.processPeriod(l)
			if state == "LookingForRows" {
				currentDecoder.Period, e = currentDecoder.getPeriod(l)
				currentDecoder.Rows = make([]PayInAAARow, 0, 10)
				if e != nil {
					log.Warn("cannot find period", l, e)
					state = "LookingForPeriod"
				} else {
					m.AAA = append(m.AAA, currentDecoder)

				}
			}
			break
		case "LookingForRows", "LookingForRowsSkipCurrent":
			nextState, row, valid := currentDecoder.processRow(l)
			if valid {
				currentDecoder.Rows = append(currentDecoder.Rows, row)
			}
			state = nextState
			if nextState == "start" {
				currentDecoder = PayInAAAPeriod{} //renew to a empty state
			}
			break
		}
	}
	return
}

func (m *PayInAAAPeriod) processStart(line string) (nextState string) {
	nextState = "start"
	if strings.Contains(line, "Loan Number") &&
		strings.Contains(line, "SettDate") &&
		strings.Contains(line, "Balance") &&
		strings.Contains(line, "IntTrail$") {
		nextState = "LookingForPeriod"
	}
	return
}

func (m *PayInAAAPeriod) processPeriod(line string) (nextState string) {
	nextState = "LookingForPeriod"
	if strings.Contains(line, "Period Servicing:") {
		nextState = "LookingForRows"
	}
	return
}

// Period Servicing: Feb 2020
func (m *PayInAAAPeriod) getPeriod(line string) (p time.Time, e error) {
	idx := strings.Index(line, ":")
	subStr := strings.TrimSpace(line[idx+1:])
	p, e = time.Parse("Jan 2006", subStr)
	return
}

func (m *PayInAAAPeriod) processRow(line string) (nextState string, row PayInAAARow, valid bool) {
	nextState = "LookingForRows"
	valid = false
	allParts := strings.Split(line, " ")
	el := make([]string, 0, 10)
	for _, item := range allParts {
		if len(item) > 0 {
			el = append(el, item)
		}
	}

	if len(el) >= 5 {
		row.LoanNumber = el[0]
		row.Settlement, _ = time.Parse("02-Jan-06", el[1])
		row.LoanAmount = m.currencyToFloat64(el[2])
		row.Balance = m.currencyToFloat64(el[3])
		row.InTrail = m.currencyToFloat64(el[len(el)-1]) //last element
		valid = true
	} else {
		if strings.Contains(line, "Total:") {
			nextState = "start"
		} else {
			nextState = "LookingForRowsSkipCurrent"
		}
	}
	return
}

func (m *PayInAAAPeriod) currencyToFloat64(cur string) (ret float64) {
	cur = strings.ReplaceAll(cur, " ", "") //remove space
	cur = strings.ReplaceAll(cur, "$", "") //remove $
	cur = strings.ReplaceAll(cur, ",", "") //remove ,
	ret, _ = strconv.ParseFloat(cur, 64)
	return ret
}