techxcar/backend/pkg/pdf/pdf.go

package pdf

import (
	"bytes"
	"encoding/base64"
	"fmt"
	"net/http"
	"os"
	"path/filepath"
	"strings"
	"time"

	"github.com/go-pdf/fpdf"
)

type DocMeta struct {
	CompanyName    string
	CompanyNIF     string
	CompanyAddress string
	CompanyIBAN    string
	CompanyPhone   string
	CompanyEmail   string
	CompanyLogo    string
	DocType        string // "Fatura" or "Orçamento"
	DocNumber      string // e.g. "FAT/2026/001"
	IssuedAt       string // e.g. "30/06/2026"
	ClientName     string
	ClientNIF      string
	VehiclePlate   string
}

type LineItem struct {
	Description string
	Qty         float64
	UnitPrice   float64
	DiscountPct float64
	Total       float64
}

func Generate(meta DocMeta, items []LineItem, staffTotal float64, outPath string) error {
	if err := os.MkdirAll(filepath.Dir(outPath), 0755); err != nil {
		return fmt.Errorf("pdf: mkdir: %w", err)
	}

	f := fpdf.New("P", "mm", "A4", "")
	f.AddPage()
	f.SetMargins(15, 15, 15)
	tr := f.UnicodeTranslatorFromDescriptor("")
	t := func(s string) string { return tr(s) }

	hasLogo := addLogo(f, meta.CompanyLogo)
	leftW := 120.0
	if hasLogo {
		leftW = 100.0
	}

	// Header
	f.SetFont("Helvetica", "B", 18)
	f.CellFormat(leftW, 10, t(meta.CompanyName), "", 0, "L", false, 0, "")
	f.SetFont("Helvetica", "B", 14)
	f.CellFormat(60, 10, t(meta.DocType), "", 1, "R", false, 0, "")

	f.SetFont("Helvetica", "", 9)
	if meta.CompanyNIF != "" {
		f.CellFormat(leftW, 5, t("NIF: ")+meta.CompanyNIF, "", 0, "L", false, 0, "")
	} else {
		f.CellFormat(leftW, 5, "", "", 0, "L", false, 0, "")
	}
	f.SetFont("Helvetica", "", 11)
	f.CellFormat(60, 5, t(meta.DocNumber), "", 1, "R", false, 0, "")

	f.SetFont("Helvetica", "", 9)
	if meta.CompanyAddress != "" {
		f.MultiCell(leftW, 5, t(meta.CompanyAddress), "", "L", false)
	}
	f.Ln(3)
	curY := f.GetY()
	f.SetXY(135, curY-3)
	f.CellFormat(60, 5, t("Data: ")+meta.IssuedAt, "", 1, "R", false, 0, "")
	f.SetY(curY + 3)
	f.Ln(3)

	// Client block
	if meta.ClientName != "" {
		f.SetFont("Helvetica", "B", 9)
		f.CellFormat(180, 5, t("Cliente"), "", 1, "L", false, 0, "")
		f.SetFont("Helvetica", "", 9)
		f.CellFormat(180, 5, t(meta.ClientName), "", 1, "L", false, 0, "")
		if meta.ClientNIF != "" {
			f.CellFormat(180, 5, t("NIF: ")+meta.ClientNIF, "", 1, "L", false, 0, "")
		}
		if meta.VehiclePlate != "" {
			f.CellFormat(180, 5, t("Matrícula: ")+meta.VehiclePlate, "", 1, "L", false, 0, "")
		}
		f.Ln(4)
	}

	// Table header
	f.SetFillColor(50, 50, 50)
	f.SetTextColor(255, 255, 255)
	f.SetFont("Helvetica", "B", 9)
	f.CellFormat(90, 7, t("Descrição"), "1", 0, "L", true, 0, "")
	f.CellFormat(20, 7, t("Qtd."), "1", 0, "C", true, 0, "")
	f.CellFormat(25, 7, t("Preço Unit."), "1", 0, "R", true, 0, "")
	f.CellFormat(20, 7, t("Desc.%"), "1", 0, "C", true, 0, "")
	f.CellFormat(25, 7, t("Total"), "1", 1, "R", true, 0, "")

	// Table rows
	f.SetFillColor(245, 245, 245)
	f.SetTextColor(0, 0, 0)
	f.SetFont("Helvetica", "", 9)
	fill := false
	for _, item := range items {
		f.CellFormat(90, 6, t(item.Description), "1", 0, "L", fill, 0, "")
		f.CellFormat(20, 6, fmt.Sprintf("%.2f", item.Qty), "1", 0, "C", fill, 0, "")
		f.CellFormat(25, 6, fmt.Sprintf("%.2f EUR", item.UnitPrice), "1", 0, "R", fill, 0, "")
		f.CellFormat(20, 6, fmt.Sprintf("%.0f%%", item.DiscountPct), "1", 0, "C", fill, 0, "")
		f.CellFormat(25, 6, fmt.Sprintf("%.2f EUR", item.Total), "1", 1, "R", fill, 0, "")
		fill = !fill
	}

	// Totals
	var subtotal float64
	for _, item := range items {
		subtotal += item.Total
	}
	grandTotal := subtotal + staffTotal

	f.Ln(3)
	f.SetFont("Helvetica", "", 9)
	if staffTotal > 0 {
		f.CellFormat(155, 6, t("Subtotal peças/serviços"), "", 0, "R", false, 0, "")
		f.CellFormat(25, 6, fmt.Sprintf("%.2f EUR", subtotal), "1", 1, "R", false, 0, "")
		f.CellFormat(155, 6, t("Mão de obra"), "", 0, "R", false, 0, "")
		f.CellFormat(25, 6, fmt.Sprintf("%.2f EUR", staffTotal), "1", 1, "R", false, 0, "")
	}
	f.SetFont("Helvetica", "B", 10)
	f.CellFormat(155, 7, t("TOTAL"), "", 0, "R", false, 0, "")
	f.CellFormat(25, 7, fmt.Sprintf("%.2f EUR", grandTotal), "1", 1, "R", false, 0, "")

	// IBAN footer
	if meta.CompanyIBAN != "" {
		f.Ln(8)
		f.SetFont("Helvetica", "", 8)
		f.CellFormat(180, 5, t("IBAN: ")+meta.CompanyIBAN, "", 1, "C", false, 0, "")
	}

	return f.OutputFileAndClose(outPath)
}

func addLogo(f *fpdf.Fpdf, logo string) bool {
	logo = strings.TrimSpace(logo)
	if logo == "" {
		return false
	}

	if strings.HasPrefix(logo, "data:image/") {
		comma := strings.Index(logo, ",")
		if comma <= 0 {
			return false
		}
		meta := logo[:comma]
		payload := logo[comma+1:]
		if !strings.Contains(meta, ";base64") {
			return false
		}
		raw, err := base64.StdEncoding.DecodeString(payload)
		if err != nil {
			return false
		}
		imgType := "PNG"
		if strings.Contains(meta, "image/jpeg") || strings.Contains(meta, "image/jpg") {
			imgType = "JPG"
		}
		opts := fpdf.ImageOptions{ImageType: imgType, ReadDpi: true}
		f.RegisterImageOptionsReader("company_logo", opts, bytes.NewReader(raw))
		f.ImageOptions("company_logo", 15, 14, 26, 0, false, opts, 0, "")
		f.SetX(45)
		return true
	}

	if strings.HasPrefix(logo, "http://") || strings.HasPrefix(logo, "https://") {
		client := http.Client{Timeout: 5 * time.Second}
		resp, err := client.Get(logo)
		if err != nil {
			return false
		}
		defer resp.Body.Close()
		if resp.StatusCode < 200 || resp.StatusCode >= 300 {
			return false
		}
		buf := new(bytes.Buffer)
		if _, err := buf.ReadFrom(resp.Body); err != nil {
			return false
		}
		imgType := "PNG"
		ct := strings.ToLower(resp.Header.Get("Content-Type"))
		if strings.Contains(ct, "jpeg") || strings.Contains(ct, "jpg") {
			imgType = "JPG"
		}
		opts := fpdf.ImageOptions{ImageType: imgType, ReadDpi: true}
		f.RegisterImageOptionsReader("company_logo", opts, bytes.NewReader(buf.Bytes()))
		f.ImageOptions("company_logo", 15, 14, 26, 0, false, opts, 0, "")
		f.SetX(45)
		return true
	}

	if _, err := os.Stat(logo); err == nil {
		opts := fpdf.ImageOptions{ReadDpi: true}
		f.ImageOptions(logo, 15, 14, 26, 0, false, opts, 0, "")
		f.SetX(45)
		return true
	}

	return false
}