Add html2pdf package

Signed-off-by: Bryan Frimin <bryan@getprobo.com>
2025-07-02 09:58:31 +02:00
parent 3697985eb4
commit a17b704934
6 changed files with 1103 additions and 0 deletions
--- a/pkg/html2pdf/converter.go
+++ b/pkg/html2pdf/converter.go
@@ -0,0 +1,163 @@
+// Copyright (c) 2025 Probo Inc <hello@getprobo.com>.
+//
+// Permission to use, copy, modify, and/or distribute this software for any
+// purpose with or without fee is hereby granted, provided that the above
+// copyright notice and this permission notice appear in all copies.
+//
+// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES WITH
+// REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF MERCHANTABILITY
+// AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY SPECIAL, DIRECT,
+// INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES WHATSOEVER RESULTING FROM
+// LOSS OF USE, DATA OR PROFITS, WHETHER IN AN ACTION OF CONTRACT, NEGLIGENCE OR
+// OTHER TORTIOUS ACTION, ARISING OUT OF OR IN CONNECTION WITH THE USE OR
+// PERFORMANCE OF THIS SOFTWARE.
+
+package html2pdf
+
+import (
+	"bytes"
+	"context"
+	_ "embed"
+	"encoding/base64"
+	"fmt"
+	"io"
+
+	"github.com/chromedp/cdproto/page"
+	"github.com/chromedp/chromedp"
+	"go.gearno.de/kit/log"
+)
+
+var (
+	waitUntilDocumentReady = func(ctx context.Context) error {
+		var ready bool
+		return chromedp.Evaluate(`document.readyState === 'complete'`, &ready).Do(ctx)
+	}
+)
+
+type (
+	RenderConfig struct {
+		PageFormat      PageFormat
+		Orientation     Orientation
+		MarginTop       Margin
+		MarginBottom    Margin
+		MarginLeft      Margin
+		MarginRight     Margin
+		PrintBackground bool
+		Scale           float64 // Print scale (0.1 to 2.0)
+	}
+
+	Option func(*Converter)
+
+	Converter struct {
+		l    *log.Logger
+		addr string
+	}
+)
+
+func WithLogger(l *log.Logger) Option {
+	return func(c *Converter) {
+		c.l = l
+	}
+}
+
+func NewConverter(addr string, opts ...Option) *Converter {
+	c := &Converter{
+		addr: addr,
+		l:    log.NewLogger(log.WithOutput(io.Discard)),
+	}
+	for _, opt := range opts {
+		opt(c)
+	}
+
+	c.l = c.l.Named("mdpdf").With(log.String("addr", addr))
+
+	return c
+}
+
+func getPageDimensions(format PageFormat, orientation Orientation) (width, height float64) {
+	var w, h float64
+
+	switch format {
+	case PageFormatA4:
+		w, h = 8.27, 11.69 // A4 in inches
+	case PageFormatLetter:
+		w, h = 8.5, 11.0 // Letter in inches
+	default:
+		w, h = 8.27, 11.69 // Default to A4
+	}
+
+	if orientation == OrientationLandscape {
+		return h, w // Swap width and height for landscape
+	}
+	return w, h
+}
+
+func (c *Converter) GeneratePDF(ctx context.Context, htmlDocument []byte, cfg RenderConfig) (io.Reader, error) {
+	allocCtx, cancel := chromedp.NewRemoteAllocator(ctx, c.addr)
+	defer cancel()
+
+	ctx, cancel = chromedp.NewContext(allocCtx)
+	defer cancel()
+
+	dataURL := fmt.Sprintf(
+		"data:text/html;base64,%s",
+		base64.StdEncoding.EncodeToString(htmlDocument),
+	)
+
+	width, height := getPageDimensions(cfg.PageFormat, cfg.Orientation)
+
+	marginTop := cfg.MarginTop.ToInches()
+	marginBottom := cfg.MarginBottom.ToInches()
+	marginLeft := cfg.MarginLeft.ToInches()
+	marginRight := cfg.MarginRight.ToInches()
+
+	scale := cfg.Scale
+	if scale <= 0 {
+		scale = 1.0
+	}
+
+	var pdfBytes []byte
+
+	c.l.InfoCtx(
+		ctx,
+		"running chromedp",
+		log.String("dataURL", dataURL),
+		log.Float64("width", width),
+		log.Float64("height", height),
+		log.Float64("marginTop", marginTop),
+		log.Float64("marginBottom", marginBottom),
+		log.Float64("marginLeft", marginLeft),
+		log.Float64("marginRight", marginRight),
+		log.Float64("scale", scale),
+		log.Bool("printBackground", cfg.PrintBackground),
+	)
+
+	err := chromedp.Run(ctx,
+		chromedp.Navigate(dataURL),
+		chromedp.WaitReady("body"),
+		chromedp.ActionFunc(waitUntilDocumentReady),
+		chromedp.ActionFunc(
+			func(ctx context.Context) (err error) {
+				pdfBytes, _, err = page.PrintToPDF().
+					WithPrintBackground(cfg.PrintBackground).
+					WithPaperWidth(width).
+					WithPaperHeight(height).
+					WithMarginTop(marginTop).
+					WithMarginBottom(marginBottom).
+					WithMarginLeft(marginLeft).
+					WithMarginRight(marginRight).
+					WithScale(scale).
+					WithPreferCSSPageSize(false).
+					Do(ctx)
+
+				return err
+			},
+		),
+	)
+
+	if err != nil {
+		return nil, fmt.Errorf("cannot run chromedp: %w", err)
+	}
+
+	return bytes.NewReader(pdfBytes), nil
+}