SFM-loan-Rest-Api/pay-in-decode.go

package main

import (
	"biukop.com/sfm/loan"
	"errors"
	log "github.com/sirupsen/logrus"
	"net/http"
	"os"
	"os/exec"
	"strings"
)

type FunderType string

const (
	Funder_AAA     FunderType = "AAA Financial"
	Funder_Pepper             = "Pepper"
	Funder_Resimac            = "Resimac"
	Funder_Unknown            = "cannot detect funder type"
)

type AiDecodeIncome struct {
	Input struct {
		Uploads  loan.Uploads
		FileName string //a local file on disk
		InMime   string //may not be correct, just some suggestion only.
	}
	Mime   string //mime actually detected.
	PayIn  []loan.PayIn
	Funder FunderType
	AAA    PayInAAAData
}

func decodePayInMain(filename string, format string) (ai AiDecodeIncome, e error) {
	ai.Input.FileName = filename
	ai.Input.InMime = format
	ai.PayIn = make([]loan.PayIn, 0, 10)
	ai.Mime, e = GetFileContentType(filename)
	if e != nil {
		return
	}

	switch ai.Mime {
	case "application/pdf":
		ai.decodePayInPdf(filename, format)
	}

	return ai, e
}

// tested, not accurate with xls, xlsx, it becomes zip and octstream sometime.
func GetFileContentType(filename string) (contentType string, e error) {
	contentType = ""
	input, e := os.OpenFile(filename, os.O_RDONLY, 0755)
	// Only the first 512 bytes are used to sniff the content type.
	buffer := make([]byte, 512)

	_, e = input.Read(buffer)
	if e != nil {
		return
	}

	// Use the net/http package's handy DectectContentType function. Always returns a valid
	// content-type by returning "application/octet-stream" if no others seemed to match.
	contentType = http.DetectContentType(buffer)
	return
}

func (m *AiDecodeIncome) decodePayInPdf(filename string, format string) (ret []loan.PayIn, e error) {
	cmd := exec.Command("pdftotext", "-layout", filename, "-")
	//log.Println(cmd.String())
	out, e := cmd.Output()
	if e != nil {
		log.Fatal(e)
	}

	raw := string(out)
	switch m.detectFunder(raw) {
	case Funder_AAA:
		e = m.AAA.decodeAAAPdf(raw)
		log.Println("AAA final result", m.AAA)
		break
	case Funder_Unknown:
		e = errors.New(Funder_Unknown)
		break // not able to detect Funder
	}
	return
}

func (m *AiDecodeIncome) detectFunder(raw string) FunderType {
	if m.isAAA(raw) {
		return Funder_AAA
	}

	return Funder_Unknown
}

func (m *AiDecodeIncome) isAAA(raw string) bool {
	keyword := "AAA Financial Trail Report"
	lines := strings.Split(raw, "\n")
	return m.checkFunderKeyword(keyword, lines, 0, 3)
}

func (m *AiDecodeIncome) checkFunderKeyword(keyword string, lines []string, start int, end int) bool {
	for idx, line := range lines {
		// first 10 lines has Key word
		if strings.Contains(line, keyword) && idx >= start && idx <= 10 {
			return true
		}
	}
	return false
}