stuve-it-backend/qrApi/main.go

package qrApi

import (
	"bytes"
	goqr "git.stuve.uni-ulm.de/stuve-it/stuve-it-backend/goqr"
	"git.stuve.uni-ulm.de/stuve-it/stuve-it-backend/logger"
	"github.com/labstack/echo/v5"
	"github.com/pocketbase/pocketbase"
	"github.com/pocketbase/pocketbase/apis"
	"github.com/pocketbase/pocketbase/core"
	"io"
)

// InitQRApi initializes ar code api endpoint
//
// this endpoint can be used to create qr codes
// GET /api/qr/v1
//
// the endpoint expects the following query params:
//
//	"data":            "what to be encoded",
//	"ecc":             "error correction level ('L', 'M' (default), 'Q', 'H')",
//	"scale":           "scale of qr code (default 1), must be greater than 0",
//	"border":          "border of qr code (default 1), must be equal or greater than 0, one is equal to one qr-code 'pixel'"
//	"color":           "color of qr code (default #000000)"
//	"colorBackground": "background color of qr code (default #FFFFFF)",
//
// if the user is authenticated successfully the endpoint returns and apis.RecordAuthResponse
func InitQRApi(app *pocketbase.PocketBase, e *core.ServeEvent) error {

	// add endpoint to app
	logger.LogInfoF("Adding QR API Endpoint")

	e.Router.GET("/api/qr/v1", func(c echo.Context) error {

		// get data from request
		data := struct {
			Data       string `query:"data"`
			ECC        string `query:"ecc"`
			Scale      int    `query:"scale"`
			Border     int    `query:"border"`
			ColorDark  string `query:"color"`
			ColorLight string `query:"colorBackground"`
		}{}
		if err := c.Bind(&data); err != nil {
			return apis.NewBadRequestError("Failed to read request data", err)
		}

		// get correct error correction level
		var errCorLvl goqr.Ecc
		switch data.ECC {
		case "L":
			errCorLvl = goqr.Low
		case "M":
			errCorLvl = goqr.Medium
		case "Q":
			errCorLvl = goqr.Quartile
		case "H":
			errCorLvl = goqr.High
		default:
			errCorLvl = goqr.Medium
		}

		// encode data to qr code
		qrCode, err := goqr.EncodeText(data.Data, errCorLvl)
		if err != nil {
			return apis.NewBadRequestError("Failed to encode data to qr code", err)
		}

		// set default scale and border
		scale := data.Scale
		border := data.Border
		if scale == 0 {
			scale = 1
		}
		if border == 0 {
			border = 1
		}
		config := goqr.NewQrCodeImgConfig(scale, border)

		// create new buffer and writer
		var buffer bytes.Buffer
		writer := io.Writer(&buffer)

		// set default colors
		colorLight := data.ColorLight
		colorDark := data.ColorDark
		if colorLight == "" {
			colorLight = "#FFFFFF"
		}
		if colorDark == "" {
			colorDark = "#000000"
		}

		// write qr code to buffer
		err = qrCode.WriteAsSVG(config, writer, colorLight, colorDark)

		// return error if writing qr code to buffer fails
		if err != nil {
			logger.LogErrorF("Failed to write QR Code: %e", err)
			return apis.NewBadRequestError("Failed to write QR Code", err)
		}

		// return qr code as svg
		return c.Stream(200, "image/svg+xml", io.Reader(&buffer))
	}, apis.ActivityLogger(app))

	return nil
}