// Package pdf provides generic document generation.
// One function, multiple document types. Linus-style.
package pdf

import (
	"bytes"
	"fmt"
	"time"

	"github.com/jung-kurt/gofpdf"
)

// DocType represents the type of document
type DocType string

const (
	InvoiceDoc DocType = "FAKTURA"
	QuoteDoc   DocType = "OFFERT"
)

// LineItem represents a single line on a document
type LineItem struct {
	Description string
	Quantity    float64
	Unit        string
	UnitPrice   float64
	Total       float64
}

// DocumentData contains all data needed to generate a document
type DocumentData struct {
	DocType         DocType
	DocNumber       string
	DocDate         time.Time
	ValidUntil      *time.Time
	CustomerName    string
	CustomerAddress string
	CustomerOrgNr   string
	Items           []LineItem
	Subtotal        float64
	VATRate         float64
	VATAmount       float64
	Total           float64
	Currency        string
	CompanyName     string
	CompanyAddress  string
	CompanyOrgNr    string
	CompanyBankgiro string
	Notes           string
}

// GenerateDocument creates a professional PDF document
func GenerateDocument(data DocumentData) ([]byte, error) {
	pdf := gofpdf.New("P", "mm", "A4", "")
	pdf.AddPage()

	// Header with document type
	pdf.SetFont("Arial", "B", 20)
	pdf.SetTextColor(201, 106, 58) // Terracotta
	pdf.Cell(0, 12, string(data.DocType))
	pdf.Ln(8)

	// Company info
	pdf.SetFont("Arial", "B", 10)
	pdf.SetTextColor(50, 50, 50)
	pdf.Cell(0, 5, data.CompanyName)
	pdf.Ln(5)
	pdf.SetFont("Arial", "", 9)
	pdf.Cell(0, 4, data.CompanyAddress)
	pdf.Ln(4)
	if data.CompanyOrgNr != "" {
		pdf.Cell(0, 4, fmt.Sprintf("Org.nr: %s", data.CompanyOrgNr))
		pdf.Ln(4)
	}
	if data.CompanyBankgiro != "" {
		pdf.Cell(0, 4, fmt.Sprintf("Bankgiro: %s", data.CompanyBankgiro))
		pdf.Ln(4)
	}
	pdf.Ln(5)

	// Document details box
	pdf.SetFillColor(250, 248, 245)
	pdf.Rect(130, 30, 70, 35, "F")
	pdf.SetXY(135, 33)
	pdf.SetFont("Arial", "B", 9)
	pdf.SetTextColor(201, 106, 58)
	pdf.Cell(0, 5, docInfoLabel(data.DocType))
	pdf.Ln(6)
	pdf.SetFont("Arial", "", 9)
	pdf.SetTextColor(50, 50, 50)
	pdf.SetX(135)
	pdf.Cell(0, 4, fmt.Sprintf("%s: %s", docNumberLabel(data.DocType), data.DocNumber))
	pdf.Ln(4)
	pdf.SetX(135)
	pdf.Cell(0, 4, fmt.Sprintf("Datum: %s", data.DocDate.Format("2006-01-02")))
	pdf.Ln(4)
	if data.ValidUntil != nil {
		pdf.SetX(135)
		pdf.Cell(0, 4, fmt.Sprintf("Giltig till: %s", data.ValidUntil.Format("2006-01-02")))
		pdf.Ln(4)
	}
	pdf.SetX(135)
	pdf.Cell(0, 4, fmt.Sprintf("Valuta: %s", data.Currency))
	pdf.Ln(4)

	// Customer info
	pdf.SetXY(10, 75)
	pdf.SetFont("Arial", "B", 10)
	pdf.SetTextColor(201, 106, 58)
	pdf.Cell(0, 5, "KUND")
	pdf.Ln(6)
	pdf.SetFont("Arial", "B", 10)
	pdf.SetTextColor(50, 50, 50)
	pdf.Cell(0, 5, data.CustomerName)
	pdf.Ln(5)
	pdf.SetFont("Arial", "", 9)
	pdf.Cell(0, 4, data.CustomerAddress)
	pdf.Ln(4)
	if data.CustomerOrgNr != "" {
		pdf.Cell(0, 4, fmt.Sprintf("Org.nr: %s", data.CustomerOrgNr))
		pdf.Ln(4)
	}
	pdf.Ln(10)

	// Items table header
	pdf.SetFillColor(201, 106, 58)
	pdf.SetTextColor(255, 255, 255)
	pdf.SetFont("Arial", "B", 9)
	pdf.Cell(80, 8, "Beskrivning")
	pdf.Cell(25, 8, "Antal")
	pdf.Cell(25, 8, "Enhet")
	pdf.Cell(30, 8, "Pris")
	pdf.Cell(30, 8, "Belopp")
	pdf.Ln(8)

	// Items
	pdf.SetTextColor(50, 50, 50)
	pdf.SetFont("Arial", "", 9)
	for i, item := range data.Items {
		if i%2 == 0 {
			pdf.SetFillColor(250, 248, 245)
			pdf.Rect(10, pdf.GetY(), 190, 6, "F")
		}
		pdf.Cell(80, 6, item.Description)
		pdf.Cell(25, 6, fmt.Sprintf("%.2f", item.Quantity))
		pdf.Cell(25, 6, item.Unit)
		pdf.Cell(30, 6, fmt.Sprintf("%.2f", item.UnitPrice))
		pdf.Cell(30, 6, fmt.Sprintf("%.2f", item.Total))
		pdf.Ln(6)
	}

	pdf.Ln(5)

	// Totals
	pdf.SetX(120)
	pdf.SetFont("Arial", "", 9)
	pdf.Cell(40, 5, "Delsumma:")
	pdf.Cell(30, 5, fmt.Sprintf("%.2f %s", data.Subtotal, data.Currency))
	pdf.Ln(5)
	pdf.SetX(120)
	pdf.Cell(40, 5, fmt.Sprintf("Moms (%.0f%%):", data.VATRate*100))
	pdf.Cell(30, 5, fmt.Sprintf("%.2f %s", data.VATAmount, data.Currency))
	pdf.Ln(5)
	pdf.SetX(120)
	pdf.SetFont("Arial", "B", 11)
	pdf.SetTextColor(201, 106, 58)
	totalLabel := "ATT BETALA:"
	if data.DocType == QuoteDoc {
		totalLabel = "TOTALT:"
	}
	pdf.Cell(40, 7, totalLabel)
	pdf.Cell(30, 7, fmt.Sprintf("%.2f %s", data.Total, data.Currency))
	pdf.Ln(10)

	// Notes
	if data.Notes != "" {
		pdf.SetFont("Arial", "I", 8)
		pdf.SetTextColor(100, 100, 100)
		pdf.MultiCell(0, 4, data.Notes, "", "", false)
	}

	// Footer
	pdf.SetY(-20)
	pdf.SetFont("Arial", "", 8)
	pdf.SetTextColor(150, 150, 150)
	pdf.Cell(0, 4, fmt.Sprintf("%s | %s %s | Sida %d", data.CompanyName, data.DocType, data.DocNumber, pdf.PageNo()))

	var buf bytes.Buffer
	if err := pdf.Output(&buf); err != nil {
		return nil, err
	}
	return buf.Bytes(), nil
}

func docInfoLabel(dt DocType) string {
	if dt == QuoteDoc {
		return "OFFERTINFORMATION"
	}
	return "FAKTURAINFORMATION"
}

func docNumberLabel(dt DocType) string {
	if dt == QuoteDoc {
		return "Offertnr"
	}
	return "Fakturanr"
}