feat(format): switch to resvg backend

Reviewed-on: #11

Dockerfile

@@ -1,11 +1,16 @@
+# Build stage
 FROM golang:latest AS builder
 WORKDIR /app
 COPY go.mod go.sum ./
 RUN go mod download
 COPY . .
-RUN go build -v -o svg-templater ./...
+RUN CGO_ENABLED=0 GOOS=linux go build -v -o svg-templater ./cmd/svg-templater
 
+# Final stage
 FROM alpine:latest
 WORKDIR /root/
+EXPOSE 3000
+VOLUME ["/var/lib/svg-templater"]
+RUN apk add inkscape fontconfig
 COPY --from=builder /app/svg-templater /usr/local/bin/svg-templater
 CMD ["svg-templater"]

cmd/svg-templater/main.go

@@ -0,0 +1,14 @@
+package main
+
+import (
+	"tomatentum.net/svg-templater/internal/command"
+	"tomatentum.net/svg-templater/pkg/format"
+)
+
+func main() {
+	if !format.CheckResvg() {
+		panic("Resvg not found")
+	}
+	command.PrepareCommandLine()
+	command.HandleCommandline()
+}

go.mod

@@ -1,3 +1,20 @@
-module svg-templater
+module tomatentum.net/svg-templater
 
 go 1.24.9
+
+require github.com/glebarez/go-sqlite v1.22.0
+
+require (
+	github.com/dustin/go-humanize v1.0.1 // indirect
+	github.com/google/uuid v1.5.0 // indirect
+	github.com/hymkor/exregexp-go v0.2.0
+	github.com/mattn/go-isatty v0.0.20 // indirect
+	github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec // indirect
+	golang.org/x/image v0.36.0
+	golang.org/x/sys v0.15.0 // indirect
+	golang.org/x/text v0.34.0 // indirect
+	modernc.org/libc v1.37.6 // indirect
+	modernc.org/mathutil v1.6.0 // indirect
+	modernc.org/memory v1.7.2 // indirect
+	modernc.org/sqlite v1.28.0 // indirect
+)

go.sum

@@ -0,0 +1,27 @@
+github.com/dustin/go-humanize v1.0.1 h1:GzkhY7T5VNhEkwH0PVJgjz+fX1rhBrR7pRT3mDkpeCY=
+github.com/dustin/go-humanize v1.0.1/go.mod h1:Mu1zIs6XwVuF/gI1OepvI0qD18qycQx+mFykh5fBlto=
+github.com/glebarez/go-sqlite v1.22.0 h1:uAcMJhaA6r3LHMTFgP0SifzgXg46yJkgxqyuyec+ruQ=
+github.com/glebarez/go-sqlite v1.22.0/go.mod h1:PlBIdHe0+aUEFn+r2/uthrWq4FxbzugL0L8Li6yQJbc=
+github.com/google/uuid v1.5.0 h1:1p67kYwdtXjb0gL0BPiP1Av9wiZPo5A8z2cWkTZ+eyU=
+github.com/google/uuid v1.5.0/go.mod h1:TIyPZe4MgqvfeYDBFedMoGGpEw/LqOeaOT+nhxU+yHo=
+github.com/hymkor/exregexp-go v0.2.0 h1:tyIB8S9gpUwiBi3aDXXXL2yIXqTMWZzW3hs+UNDqcRM=
+github.com/hymkor/exregexp-go v0.2.0/go.mod h1:bm661vkJcg9TbcYNr7QOcOgGlr+Jxy1Qb84YjVON3bg=
+github.com/mattn/go-isatty v0.0.20 h1:xfD0iDuEKnDkl03q4limB+vH+GxLEtL/jb4xVJSWWEY=
+github.com/mattn/go-isatty v0.0.20/go.mod h1:W+V8PltTTMOvKvAeJH7IuucS94S2C6jfK/D7dTCTo3Y=
+github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec h1:W09IVJc94icq4NjY3clb7Lk8O1qJ8BdBEF8z0ibU0rE=
+github.com/remyoudompheng/bigfft v0.0.0-20230129092748-24d4a6f8daec/go.mod h1:qqbHyh8v60DhA7CoWK5oRCqLrMHRGoxYCSS9EjAz6Eo=
+golang.org/x/image v0.36.0 h1:Iknbfm1afbgtwPTmHnS2gTM/6PPZfH+z2EFuOkSbqwc=
+golang.org/x/image v0.36.0/go.mod h1:YsWD2TyyGKiIX1kZlu9QfKIsQ4nAAK9bdgdrIsE7xy4=
+golang.org/x/sys v0.6.0/go.mod h1:oPkhp1MJrh7nUepCBck5+mAzfO9JrbApNNgaTdGDITg=
+golang.org/x/sys v0.15.0 h1:h48lPFYpsTvQJZF4EKyI4aLHaev3CxivZmv7yZig9pc=
+golang.org/x/sys v0.15.0/go.mod h1:/VUhepiaJMQUp4+oa/7Zr1D23ma6VTLIYjOOTFZPUcA=
+golang.org/x/text v0.34.0 h1:oL/Qq0Kdaqxa1KbNeMKwQq0reLCCaFtqu2eNuSeNHbk=
+golang.org/x/text v0.34.0/go.mod h1:homfLqTYRFyVYemLBFl5GgL/DWEiH5wcsQ5gSh1yziA=
+modernc.org/libc v1.37.6 h1:orZH3c5wmhIQFTXF+Nt+eeauyd+ZIt2BX6ARe+kD+aw=
+modernc.org/libc v1.37.6/go.mod h1:YAXkAZ8ktnkCKaN9sw/UDeUVkGYJ/YquGO4FTi5nmHE=
+modernc.org/mathutil v1.6.0 h1:fRe9+AmYlaej+64JsEEhoWuAYBkOtQiMEU7n/XgfYi4=
+modernc.org/mathutil v1.6.0/go.mod h1:Ui5Q9q1TR2gFm0AQRqQUaBWFLAhQpCwNcuhBOSedWPo=
+modernc.org/memory v1.7.2 h1:Klh90S215mmH8c9gO98QxQFsY+W451E8AnzjoE2ee1E=
+modernc.org/memory v1.7.2/go.mod h1:NO4NVCQy0N7ln+T9ngWqOQfi7ley4vpwvARR+Hjw95E=
+modernc.org/sqlite v1.28.0 h1:Zx+LyDDmXczNnEQdvPuEfcFVA2ZPyaD7UCZDjef3BHQ=
+modernc.org/sqlite v1.28.0/go.mod h1:Qxpazz0zH8Z1xCFyi5GSL3FzbtZ3fvbjmywNogldEW0=

internal/command/commandline.go

@@ -0,0 +1,50 @@
+package command
+
+import (
+	"flag"
+	"log"
+
+	"tomatentum.net/svg-templater/internal/database"
+	"tomatentum.net/svg-templater/internal/server"
+	"tomatentum.net/svg-templater/pkg/svg"
+)
+
+var (
+	help              bool
+	generateTokenFlag bool
+	deleteTokenFlag   bool
+	datapath          string
+)
+
+func PrepareCommandLine() {
+	flag.BoolVar(&help, "help", false, "Displays the help String")
+	flag.BoolVar(&generateTokenFlag, "tokengen", false, "Generate token with name")
+	flag.BoolVar(&deleteTokenFlag, "tokendel", false, "Delete token with name")
+	flag.StringVar(&datapath, "data", "/var/lib/svg-templater", "Override data directory")
+}
+
+func HandleCommandline() {
+	flag.Parse()
+
+	if !help {
+		svg.Storage = svg.NewFileStorage(datapath, "public", "fonts")
+		if err := database.OpenSQLite(datapath); err != nil {
+			log.Fatal("Failed opening DB:\n", err)
+			return
+		}
+		database.InitDB()
+	}
+	defer database.Close()
+
+	if generateTokenFlag {
+		GenerateTokenCommand()
+	} else if deleteTokenFlag {
+		DeleteTokenCommand()
+	} else if help {
+		flag.PrintDefaults()
+	} else {
+		svg.Storage = svg.NewFileStorage(datapath, "public", "fonts")
+		server.PrepareHTTP()
+		server.Start()
+	}
+}

internal/command/tokencommands.go

@@ -0,0 +1,34 @@
+package command
+
+import (
+	"flag"
+	"log"
+
+	"tomatentum.net/svg-templater/pkg/auth"
+)
+
+func GenerateTokenCommand() {
+	name := flag.Arg(0)
+	if name == "" {
+		log.Fatal("No Token Name was provided!")
+	}
+
+	token, err := auth.CreateToken(name)
+	if err != nil {
+		log.Fatal("Failed to generate token:\n", err)
+	}
+	log.Println(token)
+}
+
+func DeleteTokenCommand() {
+	name := flag.Arg(0)
+	if name == "" {
+		log.Fatal("No Token Name was provided!")
+	}
+
+	err := auth.DeleteToken(name)
+	if err != nil {
+		log.Fatal("Failed to delete token:\n", err)
+	}
+	log.Println("Deleted token " + name)
+}

internal/database/database.go

@@ -0,0 +1,36 @@
+package database
+
+import (
+	"database/sql"
+	"log"
+	"path/filepath"
+
+	_ "github.com/glebarez/go-sqlite"
+)
+
+const FILENAME string = "storage.db"
+
+var database *sql.DB
+
+func OpenSQLite(basepath string) error {
+	db, err := sql.Open("sqlite", filepath.Join(basepath, FILENAME))
+	if err != nil {
+		return err
+	}
+	log.Println("Successfully connected to SQLite Database")
+	database = db
+	return nil
+}
+
+func InitDB() {
+	_, err := database.Exec(TOKENTABLECREATE)
+	_, err = database.Exec(SVGTABLECREATE)
+	if err != nil {
+		log.Fatal("Failed to init database:\n", err)
+	}
+	log.Println("Successfully initiated the Database!")
+}
+
+func Close() error {
+	return database.Close()
+}

internal/database/svgdb.go

@@ -0,0 +1,74 @@
+package database
+
+import (
+	"encoding/json"
+
+	"tomatentum.net/svg-templater/pkg/svg"
+)
+
+const SVGTABLECREATE string = `
+	CREATE TABLE IF NOT EXISTS svg (
+		name varchar(16) PRIMARY KEY NOT NULL,
+		templatekeys longtext NOT NULL
+	);`
+
+const INSERTSVGSQL string = "INSERT INTO svg VALUES (?, ?);"
+const GETSPECIFICSVGSQL string = "SELECT * FROM svg WHERE name = ?;"
+const GETSVGSQL string = "SELECT * FROM svg;"
+
+func InsertSVG(data *svg.TemplateData) error {
+	json, err := json.Marshal(data.TemplateKeys)
+	if err != nil {
+		return err
+	}
+
+	if _, err := database.Exec(INSERTSVGSQL, data.Id, string(json)); err != nil {
+		return err
+	}
+
+	return nil
+}
+
+func GetSVG() ([]svg.TemplateData, error) {
+	result, err := database.Query(GETSVGSQL)
+	if err != nil {
+		return nil, err
+	}
+	defer result.Close()
+	templates := make([]svg.TemplateData, 0)
+	for result.Next() {
+		var (
+			id       string
+			keysjson []byte
+			keys     []string
+		)
+		if err := result.Scan(&id, &keysjson); err != nil {
+			return nil, err
+		}
+		if err := json.Unmarshal(keysjson, &keys); err != nil {
+			return nil, err
+		}
+		templates = append(templates, svg.TemplateData{Id: id, TemplateKeys: keys})
+	}
+
+	if err := result.Err(); err != nil {
+		return nil, err
+	}
+	return templates, nil
+}
+
+func GetSpecificSVG(id string) (svg.TemplateData, error) {
+	result := database.QueryRow(GETSPECIFICSVGSQL, id)
+
+	var (
+		keysjson []byte
+		keys     []string
+	)
+	if err := result.Scan(&id, &keysjson); err != nil {
+		return svg.TemplateData{}, err
+	}
+	if err := json.Unmarshal(keysjson, &keys); err != nil {
+		return svg.TemplateData{}, err
+	}
+	return svg.TemplateData{Id: id, TemplateKeys: keys}, nil
+}

internal/database/tokendb.go

@@ -0,0 +1,55 @@
+package database
+
+import (
+	"maps"
+)
+
+const TOKENTABLECREATE string = `
+	CREATE TABLE IF NOT EXISTS tokens (
+		name varchar(32) PRIMARY KEY NOT NULL,
+		token varchar(32) NOT NULL
+	);`
+
+const INSERTTOKENSQL string = "INSERT INTO tokens VALUES (?, ?);"
+const DELETETOKENSQL string = "DELETE FROM tokens WHERE name = ?;"
+const QUERYTOKENSQL string = "SELECT * FROM tokens;"
+
+var tokenCache map[string]string = make(map[string]string)
+
+func InsertToken(name string, token string) error {
+	_, err := database.Exec(INSERTTOKENSQL, name, token)
+	return err
+}
+
+func DeleteToken(name string) error {
+	_, err := database.Exec(DELETETOKENSQL, name)
+	return err
+}
+
+func ValidateTokenCache(token string) (bool, error) {
+	for v := range maps.Values(tokenCache) {
+		if token == v {
+			return true, nil
+		}
+	}
+	return ValidateToken(token)
+}
+
+func ValidateToken(token string) (bool, error) {
+	result, err := database.Query(QUERYTOKENSQL)
+	if err != nil {
+		return false, err
+	}
+	defer result.Close()
+
+	var name, foundToken string
+	for result.Next() {
+		result.Scan(&name, &foundToken)
+		tokenCache[name] = foundToken
+		if token == foundToken {
+			return true, nil
+		}
+	}
+	err = result.Err()
+	return false, err
+}

internal/routes/download.go

@@ -0,0 +1,105 @@
+package routes
+
+import (
+	"encoding/json"
+	"log"
+	"net/http"
+	"net/url"
+	"path/filepath"
+	"strconv"
+
+	"tomatentum.net/svg-templater/pkg/format"
+	"tomatentum.net/svg-templater/pkg/svg/actions"
+)
+
+type downloadRequest struct {
+	TemplateKeys map[string]string
+}
+
+type downloadResponse struct {
+	Url string
+}
+
+func DownloadSVG(w http.ResponseWriter, r *http.Request) {
+	contentType := r.Header.Get("Content-Type")
+	if contentType != "application/json" {
+		http.Error(w, "Incorrect Content-Type. Needs application/json.", http.StatusUnsupportedMediaType)
+		return
+	}
+	var request downloadRequest
+	if err := json.NewDecoder(r.Body).Decode(&request); err != nil {
+		http.Error(w, err.Error(), http.StatusBadRequest)
+		return
+	}
+
+	var err error
+	id := r.PathValue("id")
+	if id == "" {
+		http.Error(w, "No ID provided", http.StatusBadRequest)
+		return
+	}
+
+	widthString := r.URL.Query().Get("w")
+	width := 0
+	if widthString != "" {
+		width, err = strconv.Atoi(widthString)
+		if err != nil {
+			http.Error(w, "Invalid w parameter", http.StatusBadRequest)
+			return
+		}
+	}
+
+	heightString := r.URL.Query().Get("h")
+	height := 0
+	if heightString != "" {
+		height, err = strconv.Atoi(heightString)
+		if err != nil {
+			http.Error(w, "Invalid h parameter", http.StatusBadRequest)
+			return
+		}
+	}
+
+	convParam := format.ConversionParameters{
+		Format: r.URL.Query().Get("format"),
+		Width:  width,
+		Height: height,
+	}
+	if convParam.Format == "" {
+		convParam.Format = "svg"
+	}
+
+	templateParam := actions.TemplateParameters{
+		Id:   id,
+		Keys: request.TemplateKeys,
+	}
+
+	filename, err := actions.ProvideFile(&templateParam, &convParam)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	urlparsed := getPublicUrl(r, filename)
+	log.Printf("Made %s available as %s\n", id, urlparsed)
+	response := downloadResponse{
+		Url: urlparsed,
+	}
+	w.Header().Add("Content-Type", "application/json")
+	json, err := json.Marshal(response)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		return
+	}
+	w.Write(json)
+}
+
+func getPublicUrl(r *http.Request, path string) string {
+	newURL := url.URL{
+		Host: r.Host,
+		Path: filepath.Join("public", path),
+	}
+	newURL.Scheme = "http"
+	if r.TLS != nil {
+		newURL.Scheme = "https"
+	}
+	return newURL.String()
+}

internal/routes/font.go

@@ -0,0 +1,45 @@
+package routes
+
+import (
+	"encoding/json"
+	"log"
+	"net/http"
+	"strings"
+
+	"tomatentum.net/svg-templater/pkg/svg"
+)
+
+func AddFont(w http.ResponseWriter, r *http.Request) {
+	contentType := r.Header.Get("Content-Type")
+	if contentType != "font/ttf" && contentType != "font/otf" {
+		http.Error(w, "", http.StatusUnsupportedMediaType)
+		return
+	}
+	log.Println("Received font add request")
+	format := strings.TrimPrefix(contentType, "font/")
+
+	if err := svg.Storage.AddFont(r.Body, format); err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		log.Println(err)
+		return
+	}
+}
+
+func GetFonts(w http.ResponseWriter, r *http.Request) {
+	log.Println("Serving all available fonts")
+	fonts, err := svg.Storage.GetFonts()
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		log.Println(err)
+		return
+	}
+
+	json, err := json.Marshal(fonts)
+	if err != nil {
+		http.Error(w, err.Error(), http.StatusInternalServerError)
+		log.Println(err)
+		return
+	}
+	w.Header().Add("Content-Type", "application/json")
+	w.Write(json)
+}

internal/routes/upload.go

@@ -0,0 +1,49 @@
+package routes
+
+import (
+	"bytes"
+	"encoding/json"
+	"io"
+	"log"
+	"net/http"
+
+	"tomatentum.net/svg-templater/pkg/svg/actions"
+)
+
+func CreateSVG(writer http.ResponseWriter, r *http.Request) {
+
+	contentType := r.Header.Get("Content-Type")
+	if contentType != "image/svg+xml" {
+		http.Error(writer, "Incorrect Content-Type. Needs image/svg+xml.", http.StatusUnsupportedMediaType)
+		return
+	}
+
+	readsvg, err := io.ReadAll(r.Body)
+	if err != nil {
+		http.Error(writer, err.Error(), http.StatusInternalServerError)
+		log.Println("Error while reading Body\n", err)
+		return
+	}
+
+	if ok, err := validateSVG(readsvg); err != nil || !ok {
+		http.Error(writer, err.Error(), http.StatusUnsupportedMediaType)
+		log.Println("Wrong Media Type was uploaded\n", err)
+		return
+	}
+
+	data, err := actions.Create(readsvg)
+
+	if err != nil {
+		http.Error(writer, err.Error(), http.StatusInternalServerError)
+		log.Println("Failed creating SVG template\n", err)
+		return
+	}
+
+	writer.Header().Add("Content-Type", "application/json")
+	json.NewEncoder(writer).Encode(data)
+	log.Println("Created SVG Template " + data.Id)
+}
+
+func validateSVG(svgbuf []byte) (bool, error) {
+	return bytes.Contains(svgbuf[:512], []byte("<svg")), nil
+}

internal/server/http.go

@@ -0,0 +1,57 @@
+package server
+
+import (
+	"fmt"
+	"log"
+	"net/http"
+
+	"tomatentum.net/svg-templater/internal/routes"
+	"tomatentum.net/svg-templater/pkg/auth"
+	"tomatentum.net/svg-templater/pkg/svg"
+)
+
+func PrepareHTTP() {
+	registerAuthorizedFunc("/", func(w http.ResponseWriter, r *http.Request) {
+		fmt.Fprintln(w, "You are authorized!")
+	})
+	registerAuthorizedFunc("/svg/", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "POST" {
+			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+		routes.CreateSVG(w, r)
+	})
+	registerAuthorizedFunc("/svg/{id}", func(w http.ResponseWriter, r *http.Request) {
+		if r.Method != "GET" {
+			http.Error(w, "Method not allowed", http.StatusMethodNotAllowed)
+			return
+		}
+		routes.DownloadSVG(w, r)
+	})
+	registerAuthorizedFunc("/font/", func(w http.ResponseWriter, r *http.Request) {
+		switch r.Method {
+		case "GET":
+			routes.GetFonts(w, r)
+		case "POST":
+			routes.AddFont(w, r)
+		}
+	})
+
+	http.Handle("/public/", http.StripPrefix("/public/", http.FileServer(svg.Storage.GetPublicDir())))
+}
+
+func Start() {
+	log.Println("Starting http server on :3000")
+	if err := http.ListenAndServe(":3000", nil); err != nil {
+		panic(err)
+	}
+}
+
+func registerAuthorized(path string, handler http.Handler) {
+	http.HandleFunc(path, auth.AuthMiddleware(handler))
+	log.Println("Registered authorized handler for", path)
+}
+
+func registerAuthorizedFunc(path string, f func(w http.ResponseWriter, r *http.Request)) {
+	registerAuthorized(path, http.HandlerFunc(f))
+}

main.go

@@ -1,5 +0,0 @@
-package main
-
-func main() {
-	println("Hello World")
-}

pkg/auth/auth.go

@@ -0,0 +1,28 @@
+package auth
+
+import (
+	"crypto/rand"
+	"encoding/hex"
+	"log"
+
+	"tomatentum.net/svg-templater/internal/database"
+)
+
+func generateToken() string {
+	token := make([]byte, 32)
+	if _, err := rand.Read(token); err != nil {
+		log.Fatal("Failed to generate Token:\n", err)
+		return ""
+	}
+	return hex.EncodeToString(token)
+}
+
+func CreateToken(name string) (string, error) {
+	token := generateToken()
+	err := database.InsertToken(name, token)
+	return token, err
+}
+
+func DeleteToken(name string) error {
+	return database.DeleteToken(name)
+}

pkg/auth/authmiddleware.go

@@ -0,0 +1,40 @@
+package auth
+
+import (
+	"log"
+	"net/http"
+	"strings"
+
+	"tomatentum.net/svg-templater/internal/database"
+)
+
+func AuthMiddleware(next http.Handler) http.HandlerFunc {
+	return http.HandlerFunc(func(w http.ResponseWriter, r *http.Request) {
+		valid, err := validateAuthHeader(r)
+		if err != nil {
+			http.Error(w, "Internal Server Error", http.StatusInternalServerError)
+			log.Println("Database Query for token validation failed.\n", r)
+			return
+		}
+
+		if valid {
+			next.ServeHTTP(w, r)
+		} else {
+			http.Error(w, "Unauthorized", http.StatusUnauthorized)
+		}
+	})
+}
+
+// Accepts ("Authorization": "BEARER <TOKEN>"), returns database error if query failed
+func validateAuthHeader(r *http.Request) (bool, error) {
+	header := strings.Split(r.Header.Get("Authorization"), " ")
+	if len(header) < 2 {
+		return false, nil
+	}
+	token := header[1]
+	if len(strings.TrimSpace(token)) < 1 {
+		return false, nil
+	}
+
+	return database.ValidateTokenCache(token)
+}

pkg/format/formatconverter.go

@@ -0,0 +1,96 @@
+package format
+
+import (
+	"bytes"
+	"errors"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"os/exec"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"tomatentum.net/svg-templater/pkg/svg"
+)
+
+type ConversionParameters struct {
+	Format        string
+	Width, Height int
+}
+
+func ConvertByte(svgblob []byte, param ConversionParameters) ([]byte, error) {
+	reader, err := ConvertReader(svgblob, param)
+	if err != nil {
+		return nil, err
+	}
+	defer reader.Close()
+
+	result, err := io.ReadAll(reader)
+	if err != nil {
+		return nil, err
+	}
+	return result, nil
+}
+
+func ConvertReader(svgblob []byte, param ConversionParameters) (io.ReadCloser, error) {
+	if param.Format == "svg" {
+		return io.NopCloser(bytes.NewReader(svgblob)), nil
+	}
+	file, err := svg.CreateTemp(bytes.NewReader(svgblob), "svg")
+	if err != nil {
+		return nil, err
+	}
+	defer os.Remove(file)
+
+	switch param.Format {
+	case "png":
+		return convertPNG(file, param)
+	}
+	return nil, errors.New("Format not supported")
+}
+
+func convertPNG(input string, param ConversionParameters) (io.ReadCloser, error) {
+	var args []string
+	var outExt string
+
+	fontsdir, err := svg.Storage.GetFontsDir()
+	if err != nil {
+		return nil, err
+	}
+	args = append(args, "--skip-system-fonts")
+	args = append(args, "--use-fonts-dir", fontsdir)
+
+	if param.Width > 0 {
+		args = append(args, "-w", strconv.Itoa(param.Width))
+	}
+	if param.Height > 0 {
+		args = append(args, "-h", strconv.Itoa(param.Height))
+	}
+
+	outFile := strings.TrimSuffix(input, filepath.Ext(input)) + outExt
+	args = append(args, input)
+	args = append(args, outFile)
+
+	cmd := exec.Command("resvg", args...)
+	cmd.Dir = svg.TempDir
+
+	out, err := cmd.CombinedOutput()
+	log.Println(string(out))
+	if err != nil {
+		return nil, fmt.Errorf("resvg failed: %w: %s", err, string(out))
+	}
+
+	file, err := os.Open(outFile)
+	if err != nil {
+		return nil, err
+	}
+
+	return file, nil
+}
+
+func CheckResvg() bool {
+	_, err := exec.LookPath("resvg")
+	return err == nil
+}

pkg/svg/actions/download.go

@@ -0,0 +1,22 @@
+package actions
+
+import (
+	"bytes"
+	"log"
+
+	"tomatentum.net/svg-templater/pkg/format"
+	"tomatentum.net/svg-templater/pkg/svg"
+)
+
+func ProvideFile(r *TemplateParameters, conversion *format.ConversionParameters) (string, error) {
+	templatedSvgblob, err := Template(r)
+	if err != nil {
+		return "", err
+	}
+	log.Printf("Converting %s to format %s (w=%d,h=%d)", r.Id, conversion.Format, conversion.Width, conversion.Height)
+	result, err := format.ConvertByte(templatedSvgblob, *conversion)
+	if err != nil {
+		return "", err
+	}
+	return svg.Storage.CreatePublic(bytes.NewReader(result), conversion.Format)
+}

pkg/svg/actions/template.go

@@ -0,0 +1,66 @@
+package actions
+
+import (
+	"errors"
+	"io"
+	"log"
+	"maps"
+	"regexp"
+	"slices"
+
+	"github.com/hymkor/exregexp-go"
+	"tomatentum.net/svg-templater/internal/database"
+	"tomatentum.net/svg-templater/pkg/svg"
+)
+
+type TemplateParameters struct {
+	Id   string
+	Keys map[string]string
+}
+
+func Template(r *TemplateParameters) ([]byte, error) {
+	mapkeys := slices.Collect(maps.Keys(r.Keys))
+	ok, err := verifyTemplate(r.Id, mapkeys)
+	if err != nil {
+		return nil, err
+	}
+	if !ok {
+		return nil, errors.New("Template does not exist.")
+	}
+	log.Printf("Replacing keys of %s template\n", r.Id)
+
+	reader, err := svg.Storage.Get(r.Id)
+	if err != nil {
+		return nil, err
+	}
+	defer reader.Close()
+	svgblob, err := io.ReadAll(reader)
+	if err != nil {
+		return nil, err
+	}
+	replaceAll(&svgblob, r.Keys)
+	log.Printf("Finished replacing keys of %s template\n", r.Id)
+	return svgblob, nil
+}
+
+func replaceAll(svgblob *[]byte, keys map[string]string) {
+	regex := regexp.MustCompile(svg.KeyRegex)
+	*svgblob = []byte(exregexp.ReplaceAllStringSubmatchFunc(regex, string(*svgblob), func(s []string) string {
+		log.Printf("Replacing key %s with %s\n", s[1], keys[s[1]])
+		return keys[s[1]]
+	}))
+}
+
+func verifyTemplate(id string, keys []string) (bool, error) {
+	data, err := database.GetSpecificSVG(id)
+	if err != nil {
+		return false, err
+	}
+
+	for _, key := range data.TemplateKeys {
+		if !slices.Contains(keys, key) {
+			return false, nil
+		}
+	}
+	return true, nil
+}

pkg/svg/actions/upload.go

@@ -0,0 +1,50 @@
+package actions
+
+import (
+	"bytes"
+	"crypto/rand"
+	"encoding/hex"
+	"log"
+	"regexp"
+
+	"tomatentum.net/svg-templater/internal/database"
+	"tomatentum.net/svg-templater/pkg/svg"
+)
+
+func Create(svgbuf []byte) (svg.TemplateData, error) {
+	data := svg.TemplateData{Id: generateId(), TemplateKeys: nil}
+	populateKeys(&data, svgbuf)
+
+	_, err := svg.Storage.Create(data.Id, bytes.NewReader(svgbuf))
+	if err != nil {
+		return svg.TemplateData{}, err
+	}
+
+	if err := database.InsertSVG(&data); err != nil {
+		return svg.TemplateData{}, err
+	}
+
+	return data, nil
+}
+
+func populateKeys(data *svg.TemplateData, svgblob []byte) {
+	regex := regexp.MustCompile(svg.KeyRegex)
+	result := regex.FindAllSubmatch(svgblob, -1)
+	templateKeys := make([]string, len(result))
+
+	for i, matches := range result {
+		varname := matches[1] // first capture group
+		templateKeys[i] = string(varname)
+	}
+	data.TemplateKeys = templateKeys
+	log.Println("Found keys:\n", templateKeys)
+}
+
+func generateId() string {
+	token := make([]byte, 16)
+	if _, err := rand.Read(token); err != nil {
+		log.Fatal("Failed to generate Token:\n", err)
+		return ""
+	}
+	return hex.EncodeToString(token)
+}

pkg/svg/storage.go

@@ -0,0 +1,174 @@
+package svg
+
+import (
+	"errors"
+	"io"
+	"log"
+	"net/http"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"golang.org/x/image/font/sfnt"
+)
+
+type SvgStorage interface {
+	Create(id string, svg io.Reader) (string, error)
+	Get(id string) (io.ReadCloser, error)
+	AddFont(reader io.Reader, format string) error
+	GetFonts() ([]string, error)
+	GetFontsDir() (string, error)
+	CreatePublic(data io.Reader, filetype string) (string, error)
+	GetPublic(path string) (io.ReadCloser, error)
+	GetPublicDir() http.Dir
+}
+
+var _ SvgStorage = FileSvgStorage{}
+var TempDir string = ""
+
+type FileSvgStorage struct {
+	basepath, publicSubPath, fontssubpath string
+}
+
+func NewFileStorage(path, publicSubPath, fontssubpath string) *FileSvgStorage {
+	err := os.MkdirAll(path, 0755)
+	if err != nil {
+		panic(err)
+	}
+	err = os.MkdirAll(filepath.Join(path, fontssubpath), 0755)
+	if err != nil {
+		panic(err)
+	}
+	log.Println("Initialized file storage handler")
+	return &FileSvgStorage{path, publicSubPath, fontssubpath}
+}
+
+func (f FileSvgStorage) Create(id string, svg io.Reader) (string, error) {
+	file, err := os.Create(filepath.Join(f.basepath, id+".svg"))
+
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+
+	_, err = io.Copy(file, svg)
+	if err != nil {
+		return "", err
+	}
+
+	log.Println("Created File: ", file.Name())
+	return file.Name(), nil
+}
+
+func (f FileSvgStorage) Get(id string) (io.ReadCloser, error) {
+	file, err := os.Open(filepath.Join(f.basepath, id+".svg"))
+	if err != nil {
+		return nil, err
+	}
+	return file, nil
+}
+
+func (f FileSvgStorage) CreatePublic(data io.Reader, filetype string) (string, error) {
+	path := filepath.Join(f.basepath, f.publicSubPath)
+	if err := os.MkdirAll(path, 0755); err != nil {
+		return "", err
+	}
+
+	file, err := os.CreateTemp(path, "*."+filetype)
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+	_, err = io.Copy(file, data)
+	if err != nil {
+		return "", err
+	}
+
+	return strings.TrimPrefix(file.Name(), path), nil
+}
+
+func (f FileSvgStorage) GetPublic(path string) (io.ReadCloser, error) {
+	file, err := os.Open(filepath.Join(f.basepath, f.publicSubPath, path))
+	if err != nil {
+		return nil, err
+	}
+	return file, nil
+}
+
+func (f FileSvgStorage) GetPublicDir() http.Dir {
+	return http.Dir(filepath.Join(f.basepath, f.publicSubPath))
+}
+
+func CreateTemp(data io.Reader, filetype string) (string, error) {
+	file, err := os.CreateTemp(TempDir, "*."+filetype)
+	if err != nil {
+		return "", err
+	}
+	defer file.Close()
+	_, err = io.Copy(file, data)
+	if err != nil {
+		return "", err
+	}
+
+	return file.Name(), nil
+}
+
+func (f FileSvgStorage) AddFont(fontreader io.Reader, format string) error {
+	if format != "ttf" && format != "otf" {
+		return errors.New("Format not supported")
+	}
+	file, err := os.CreateTemp(filepath.Join(f.basepath, f.fontssubpath), "*."+format)
+	if err != nil {
+		return err
+	}
+	defer file.Close()
+	log.Printf("Writing %s font to %s\n", format, file.Name())
+	_, err = io.Copy(file, fontreader)
+	if err != nil {
+		return err
+	}
+	return nil
+}
+
+func (f FileSvgStorage) GetFonts() ([]string, error) {
+	path := filepath.Join(f.basepath, f.fontssubpath)
+	entries, err := os.ReadDir(path)
+	if err != nil {
+		return nil, err
+	}
+	fonts := make([]string, len(entries))
+	for i, entry := range entries {
+		if entry.IsDir() {
+			continue
+		}
+		if strings.HasSuffix(entry.Name(), ".ttf") || strings.HasSuffix(entry.Name(), ".otf") {
+			fontblob, err := os.ReadFile(filepath.Join(path, entry.Name()))
+			if err != nil {
+				return nil, err
+			}
+			fontname, err := getFontName(fontblob)
+			if err != nil {
+				return nil, err
+			}
+			fonts[i] = fontname
+		}
+	}
+	log.Printf("Got fonts \n%s\n", strings.Join(fonts, "\n"))
+	return fonts, nil
+}
+
+func (f FileSvgStorage) GetFontsDir() (string, error) {
+	return filepath.Join(f.basepath, f.fontssubpath), nil
+}
+
+func getFontName(svgblob []byte) (string, error) {
+	font, err := sfnt.Parse(svgblob)
+	if err != nil {
+		return "", err
+	}
+	name, err := font.Name(nil, sfnt.NameIDFull)
+	if err != nil {
+		return "", err
+	}
+	return name, nil
+}

pkg/svg/templates.go

@@ -0,0 +1,10 @@
+package svg
+
+const KeyRegex string = `\{\{\s*(.*?)\s*\}\}`
+
+type TemplateData struct {
+	Id           string
+	TemplateKeys []string
+}
+
+var Storage SvgStorage