feat(services): Implement pdf conversion through gotenberg

services/converter.go

@@ -0,0 +1,107 @@
+package services
+
+import (
+	"bytes"
+	"fmt"
+	"mime/multipart"
+	"net/http"
+	"strconv"
+
+	"github.com/oxplot/papersizes"
+)
+
+type Converter interface {
+	ToPdf(html string, pageSize string, landscape bool) ([]byte, error)
+}
+
+type GotenbergConverter struct {
+	BaseUrl string
+}
+
+func (g *GotenbergConverter) ToPdf(html string, pageSize string, landscape bool) ([]byte, error) {
+	client := &http.Client{}
+	defer client.CloseIdleConnections()
+
+	body := &bytes.Buffer{}
+	writer := multipart.NewWriter(body)
+
+	part, err := writer.CreateFormFile("files", "index.html")
+	if err != nil {
+		return nil, err
+	}
+
+	_, err = part.Write([]byte(html))
+	if err != nil {
+		return nil, err
+	}
+
+	size := papersizes.FromName(pageSize)
+	if size == nil {
+		return nil, fmt.Errorf("invalid page size: %s", pageSize)
+	}
+
+	err = writer.WriteField("paperWidth", strconv.Itoa(size.Width)+"mm")
+	if err != nil {
+		return nil, err
+	}
+
+	err = writer.WriteField("paperHeight", strconv.Itoa(size.Height)+"mm")
+	if err != nil {
+		return nil, err
+	}
+
+	err = writer.WriteField("landscape", strconv.FormatBool(landscape))
+	if err != nil {
+		return nil, err
+	}
+
+	err = writer.WriteField("marginTop", "0")
+	if err != nil {
+		return nil, err
+	}
+
+	err = writer.WriteField("marginBottom", "0")
+	if err != nil {
+		return nil, err
+	}
+
+	err = writer.WriteField("marginLeft", "0")
+	if err != nil {
+		return nil, err
+	}
+
+	err = writer.WriteField("marginRight", "0")
+	if err != nil {
+		return nil, err
+	}
+
+	err = writer.WriteField("preferCssPageSize", "true")
+	if err != nil {
+		return nil, err
+	}
+
+	err = writer.Close()
+	if err != nil {
+		return nil, err
+	}
+
+	req, err := http.NewRequest("POST", g.BaseUrl+"/forms/chromium/convert/html", body)
+	if err != nil {
+		return nil, err
+	}
+	req.Header.Set("Content-Type", writer.FormDataContentType())
+
+	resp, err := client.Do(req)
+	if err != nil {
+		return nil, err
+	}
+
+	defer resp.Body.Close()
+	data := new(bytes.Buffer)
+	_, err = data.ReadFrom(resp.Body)
+	if err != nil {
+		return nil, err
+	}
+
+	return data.Bytes(), nil
+}