package render

import (
	"bytes"
	"embed"
	"html/template"
	"time"

	"github.com/russross/blackfriday/v2"

	"beelloo/internal/invoice"
)

//go:embed template.html style.css
var assets embed.FS

type renderItem struct {
	Designation template.HTML
	UnitPrice   string
	Quantity    string
	Amount      string
}

type renderData struct {
	Seller             invoice.Party
	Buyer              invoice.Party
	Invoice            invoice.InvoiceInfo
	InvoiceDate        string
	InvoiceDescription template.HTML
	Items              []renderItem
	TotalExclTax       string
	Payment            invoice.PaymentInfo
	CSS                template.CSS
	CSSHref            string
}

func RenderHTML(doc invoice.Document) (string, error) {
	cssBytes, err := assets.ReadFile("style.css")
	if err != nil {
		return "", err
	}
	return RenderHTMLWithCSS(doc, string(cssBytes))
}

func RenderHTMLWithCSS(doc invoice.Document, css string) (string, error) {
	return renderHTML(doc, css, "")
}

func RenderHTMLWithCSSLink(doc invoice.Document, href string) (string, error) {
	return renderHTML(doc, "", href)
}

func renderHTML(doc invoice.Document, css string, href string) (string, error) {
	invoice.ComputeTotals(&doc)
	tmplBytes, err := assets.ReadFile("template.html")
	if err != nil {
		return "", err
	}
	tmpl, err := template.New("invoice").Parse(string(tmplBytes))
	if err != nil {
		return "", err
	}
	data := renderData{
		Seller:             doc.Seller,
		Buyer:              doc.Buyer,
		Invoice:            doc.Invoice,
		InvoiceDate:        formatDate(doc.Invoice.Date),
		InvoiceDescription: markdownHTML(doc.Invoice.Description),
		TotalExclTax:       invoice.FormatMoney(doc.Totals.TotalExclTax),
		Payment:            doc.Payment,
		CSS:                template.CSS(css),
		CSSHref:            href,
	}
	for _, item := range doc.Items {
		data.Items = append(data.Items, renderItem{
			Designation: markdownHTML(item.Designation),
			UnitPrice:   invoice.FormatMoney(item.UnitPrice),
			Quantity:    invoice.FormatQuantity(item.Quantity),
			Amount:      invoice.FormatMoney(invoice.LineAmount(item)),
		})
	}
	var buf bytes.Buffer
	if err := tmpl.Execute(&buf, data); err != nil {
		return "", err
	}
	return buf.String(), nil
}

func DefaultCSS() ([]byte, error) {
	return assets.ReadFile("style.css")
}

func markdownHTML(input string) template.HTML {
	output := blackfriday.Run([]byte(input))
	return template.HTML(output)
}

func formatDate(date time.Time) string {
	if date.IsZero() {
		return ""
	}
	return date.Format("02/01/2006")
}