package main

import (
	"fmt"
	"github.com/jung-kurt/gofpdf"
	"golang.org/x/text/language"
	"golang.org/x/text/message"
	"gopkg.in/yaml.v2"
	"io/ioutil"
	"log"
	"math"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
)

// Metadata type
type Metadata struct {
	InvoiceNr   string  `yaml:"invoice_nr"`
	InvoiceInfo string  `yaml:"invoice_info"`
	InvoiceDate string  `yaml:"invoice_date"`
	Vat         float64 `yaml:"vat"`
	Account     string  `yaml:"account"`
	DueDate     string  `yaml:"due_date"`
	VatNumber   string  `yaml:"vat_number"`
}

// Address type
type Address struct {
	Name   string `yaml:"name"`
	Street string `yaml:"street"`
	Zip    string `yaml:"zip"`
	City   string `yaml:"city"`
	TelNo  string `yaml:"tel_no"`
	Email  string `yaml:"email"`
}

// InvoiceItem type
type InvoiceItem struct {
	Text         string  `yaml:"text"`
	Quantity     float64 `yaml:"quantity"`
	PricePerUnit float64 `yaml:"price_per_unit"`
}

// InvoiceData type
type InvoiceData struct {
	Metadata       Metadata      `yaml:"metadata"`
	SenderAddress  Address       `yaml:"sender_address"`
	BillingAddress Address       `yaml:"billing_address"`
	InvoiceItems   []InvoiceItem `yaml:"invoice_items"`
}

/* global variable declaration */
var pdf *gofpdf.Fpdf
var yPos float64
var invoiceData InvoiceData
var progDir string
var currentPage int
var totalPages int
var totalItemLines int
var totalNetAmount float64
var totalInvoiceAmount float64

const defaultFontSize = 9
const marginTop = 7
const logoTop = 6
const logoHeight = 20
const lineSpacing = 5
const lineSpacingSmall = 3.5
const addressTop = 50
const metadataTopFirstPage = 70
const metadataTopNotFirstPage = 30
const tabstopLeft = 20
const tabstopLeftAlt = 40
const tabstopMetadata = 60
const tabstopAddress = 120
const tabstopLogo = 155
const tabstopRight = 200
const widthItemText = 96
const widthQuantity = 28
const widthPricePerUnit = 28
const widthPrice = 28
const tabstopQuantity = tabstopRight - widthPrice - widthPricePerUnit - widthQuantity
const tabstopPricePerUnit = tabstopRight - widthPrice - widthPricePerUnit
const tabstopPrice = tabstopRight - widthPrice
const itemsTopFirstPage = 105
const itemsTopNotFirstPage = 50
const totalsTop = 165
const maxYPos = 265

func round5rappen(f float64) float64 {
	return (math.Round(f*20) / 20)
}

func floatToString(f float64) string {
	p := message.NewPrinter(language.English)
	s := strings.ReplaceAll(p.Sprintf("%.2f", f), ",", "'")
	fmt.Printf("--- s: @%s@\n", s)
	return s
}

func readInvoiceData(filename string) {
	data, err := ioutil.ReadFile(filename)
	if err != nil {
		log.Fatal(err)
	}

	//fmt.Printf("File contents: %s", data)

	err = yaml.Unmarshal([]byte(data), &invoiceData)
	if err != nil {
		log.Fatalf("error: %v", err)
	}

	fmt.Printf("--- t:\n%v\n\n", invoiceData)
	fmt.Printf("%s\n", invoiceData.BillingAddress.Name)
}

func writeText(x float64, y float64, w float64, text string, alignStr ...string) {
	tr := pdf.UnicodeTranslatorFromDescriptor("")
	align := "LT"
	if len(alignStr) > 0 {
		align = alignStr[0]
	}
	pdf.SetXY(x, y)
	pdf.CellFormat(w, 11, tr(text), "", 0, align, false, 0, "")
}

func setupInvoice() {
	pdf = gofpdf.New("P", "mm", "A4", "")
	pdf.SetMargins(0, 0, 0)
	pdf.SetFontLocation("fonts")
	pdf.AddFont("Dejavusans", "", "DejaVuSans.json")
	pdf.AddFont("Dejavusans-Bold", "", "DejaVuSans-Bold.json")
	pdf.SetFont("Dejavusans", "", defaultFontSize)
	currentPage = 0
}

func printPageHeader(firstPage bool) {
	var opt gofpdf.ImageOptions

	currentPage = currentPage + 1
	pdf.AddPage()
	yPos = marginTop
	pdf.SetFont("Dejavusans-Bold", "", defaultFontSize)
	writeText(tabstopLeft, yPos, 0, invoiceData.SenderAddress.Name)
	pdf.SetFont("Dejavusans", "", defaultFontSize)
	yPos = yPos + lineSpacing
	writeText(tabstopLeft, yPos, 0, invoiceData.SenderAddress.Street)
	yPos = yPos + lineSpacing
	writeText(tabstopLeft, yPos, 0, invoiceData.SenderAddress.Zip+" "+invoiceData.SenderAddress.City)
	if firstPage {
		yPos = yPos + lineSpacing
		yPos = yPos + lineSpacing
		writeText(tabstopLeft, yPos, 0, "Telefon")
		writeText(tabstopLeftAlt, yPos, 0, invoiceData.SenderAddress.TelNo)
		yPos = yPos + lineSpacing
		writeText(tabstopLeft, yPos, 0, "E-Mail")
		writeText(tabstopLeftAlt, yPos, 0, invoiceData.SenderAddress.Email)
		yPos = yPos + lineSpacing
		writeText(tabstopLeft, yPos, 0, "MwSt. Nr.")
		writeText(tabstopLeftAlt, yPos, 0, invoiceData.Metadata.VatNumber)
	}

	opt.ImageType = "png"
	opt.ReadDpi = true
	pdf.ImageOptions("logos/nbit-logo-40x20mm-400dpi.png", tabstopLogo, logoTop, 0, logoHeight, false, opt, 0, "")
	pdf.SetFont("Dejavusans", "", defaultFontSize)
}

func printAddress() {
	yPos = addressTop
	writeText(tabstopAddress, yPos, 0, invoiceData.BillingAddress.Name)
	yPos = yPos + lineSpacing
	writeText(tabstopAddress, yPos, 0, invoiceData.BillingAddress.Street)
	yPos = yPos + lineSpacing
	writeText(tabstopAddress, yPos, 0, invoiceData.BillingAddress.Zip+" "+invoiceData.BillingAddress.City)
}

func printMetadata(firstPage bool) {
	yPos = metadataTopNotFirstPage
	if firstPage {
		yPos = metadataTopFirstPage
		pdf.SetFont("Dejavusans-Bold", "", 16)
		writeText(tabstopLeft, yPos, 0, "Rechnung")
		yPos = yPos + lineSpacing
		yPos = yPos + lineSpacing
	}
	pdf.SetFont("Dejavusans-Bold", "", defaultFontSize)
	writeText(tabstopLeft, yPos, 0, "Rechnungsnummer:")
	pdf.SetFont("Dejavusans", "", defaultFontSize)
	writeText(tabstopMetadata, yPos, 0, invoiceData.Metadata.InvoiceNr)
	yPos = yPos + lineSpacing
	if firstPage {
		pdf.SetFont("Dejavusans-Bold", "", defaultFontSize)
		writeText(tabstopLeft, yPos, 0, "Rechnungsdatum:")
		pdf.SetFont("Dejavusans", "", defaultFontSize)
		writeText(tabstopMetadata, yPos, 0, invoiceData.Metadata.InvoiceDate)
		yPos = yPos + lineSpacing
	} 
	pdf.SetFont("Dejavusans-Bold", "", defaultFontSize)
	writeText(tabstopLeft, yPos, 0, "Seite:")
	pdf.SetFont("Dejavusans", "", defaultFontSize)
	writeText(tabstopMetadata, yPos, 0, fmt.Sprintf("%d von %d", currentPage, totalPages))
}

func printItemsHeader() {
	if currentPage == 1 {
		yPos = itemsTopFirstPage
	} else {
		yPos = itemsTopNotFirstPage
	}
	pdf.SetFont("Dejavusans-Bold", "", defaultFontSize)
	writeText(tabstopLeft, yPos, 0, "Bezeichnung")
	writeText(tabstopQuantity, yPos, widthQuantity, "Menge", "TR")
	writeText(tabstopPricePerUnit, yPos, widthPricePerUnit, "Einheitspreis", "TR")
	writeText(tabstopPrice, yPos, widthPrice, "Preis", "TR")
	pdf.SetFont("Dejavusans", "", defaultFontSize)
	yPos = yPos + lineSpacing
	pdf.Line(tabstopLeft, yPos, tabstopRight, yPos)
	yPos = yPos + lineSpacing
}

func maybeNewPage() {
	if yPos > maxYPos {
		printPageHeader(false)
		printMetadata(false)
		printItemsHeader()
	}
}

func printItems() {
	for _, i := range invoiceData.InvoiceItems {
		if i.Quantity != 0 {
			writeText(tabstopQuantity, yPos, widthQuantity, fmt.Sprintf("%.1f", i.Quantity), "TR")
			writeText(tabstopPricePerUnit, yPos, widthPricePerUnit, fmt.Sprintf("%.2f", i.PricePerUnit), "TR")
			itemNetAmount := round5rappen(i.Quantity * i.PricePerUnit)
			totalNetAmount = totalNetAmount + itemNetAmount
			writeText(tabstopPrice, yPos, widthPrice, floatToString(itemNetAmount), "TR")
		}
		if i.Text != "" {
			lines := pdf.SplitText(i.Text, widthItemText)
			for _, il := range lines {
				totalItemLines = totalItemLines + 1
				writeText(tabstopLeft, yPos, 0, strings.ReplaceAll(il, "_", " "))
				yPos = yPos + lineSpacing
				maybeNewPage()
			}
		} else {
			totalItemLines = totalItemLines + 1
			yPos = yPos + lineSpacing
			maybeNewPage()
		}
	}
}

func printTotals() {
	yPos = totalsTop
	pdf.Line(tabstopRight-widthPrice, yPos, tabstopRight, yPos)
	pdf.SetFont("Dejavusans-Bold", "", defaultFontSize)
	yPos = yPos + lineSpacing
	writeText(tabstopLeft, yPos, 0, "Netto Betrag")
	writeText(tabstopPrice, yPos, widthPrice, floatToString(totalNetAmount), "TR")
	yPos = yPos + lineSpacing
	yPos = yPos + lineSpacing
	writeText(tabstopLeft, yPos, 0, fmt.Sprintf("MwSt. %.1f%%", invoiceData.Metadata.Vat))
	mwstAmount := round5rappen(totalNetAmount * invoiceData.Metadata.Vat / 100)
	writeText(tabstopPrice, yPos, widthPrice, floatToString(mwstAmount), "TR")
	yPos = yPos + lineSpacing
	yPos = yPos + lineSpacing
	writeText(tabstopLeft, yPos, 0, "Total Betrag sFr.")
	totalInvoiceAmount = totalNetAmount + mwstAmount
	writeText(tabstopPrice, yPos, widthPrice, floatToString(totalNetAmount+mwstAmount), "TR")
}

func printQR() {
	var opt gofpdf.ImageOptions

	cmd := exec.Command(filepath.Join(progDir, "qrbill.sh"),
		"--account", invoiceData.Metadata.Account,
		"--amount", floatToString(totalInvoiceAmount),
		"--creditor-name", invoiceData.SenderAddress.Name,
		"--creditor-street", invoiceData.SenderAddress.Street,
		"--creditor-postalcode", invoiceData.SenderAddress.Zip,
		"--creditor-city", invoiceData.SenderAddress.City,
		"--extra-infos", invoiceData.Metadata.InvoiceInfo,
		"--debtor-name", invoiceData.BillingAddress.Name,
		"--debtor-street", invoiceData.BillingAddress.Street,
		"--debtor-postalcode", invoiceData.BillingAddress.Zip,
		"--debtor-city", invoiceData.BillingAddress.City,
		"--due-date", invoiceData.Metadata.DueDate,
		"--language", "de")
	cmd.Env = append(os.Environ(),
		"INVNO="+invoiceData.Metadata.InvoiceNr,
	)
	stdoutStderr, err := cmd.CombinedOutput()
	fmt.Printf("%s\n", stdoutStderr)
	if err != nil {
		log.Fatal(err)
	}
	fmt.Printf("%s\n", stdoutStderr)

	opt.ImageType = "png"
	opt.ReadDpi = true
	pdf.ImageOptions("qr-images/"+invoiceData.Metadata.InvoiceNr+".png", 0, 200, -1, -1, false, opt, 0, "")
}

func CreateInvoice() {
	totalNetAmount = 0
	totalItemLines = 0
	readInvoiceData(os.Args[1])
	setupInvoice()
	printPageHeader(true)
	printAddress()
	printMetadata(true)
	printItemsHeader()
	printItems()
	printTotals()
	printQR()
}

func main() {
	dir, err := filepath.Abs(filepath.Dir(os.Args[0]))
	if err != nil {
		log.Fatal(err)
	}
	progDir = dir

	if len(os.Args) != 2 {
		fmt.Printf("usage: mkinvoice <yaml-file>\n")
		os.Exit(1)
	}

	// First Run to get total number of pages
	CreateInvoice()
	totalPages = pdf.PageNo()
	fmt.Printf("Total Pages is: %d\n", totalPages)
	fmt.Printf("Total Item Lines is: %d\n", totalItemLines)

	// Second Run
	CreateInvoice()

	err = pdf.OutputFileAndClose(filepath.Join(progDir, "output", invoiceData.Metadata.InvoiceNr+".pdf"))
	if err == nil {
		fmt.Printf("Successfully created invoice\n")
	} else {
		fmt.Printf("Error: %v\n", err)
	}
}