initial commit

config.go

@@ -0,0 +1,192 @@
+/*
+Copyright © 2024 Thomas von Dein
+
+This program is free software: you can redistribute it and/or modify
+it under the terms of the GNU General Public License as published by
+the Free Software Foundation, either version 3 of the License, or
+(at your option) any later version.
+
+This program is distributed in the hope that it will be useful,
+but WITHOUT ANY WARRANTY; without even the implied warranty of
+MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+GNU General Public License for more details.
+
+You should have received a copy of the GNU General Public License
+along with this program. If not, see <http://www.gnu.org/licenses/>.
+*/
+
+package main
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strconv"
+	"strings"
+
+	"github.com/knadh/koanf/parsers/toml"
+	"github.com/knadh/koanf/providers/file"
+	"github.com/knadh/koanf/providers/posflag"
+	"github.com/knadh/koanf/v2"
+	flag "github.com/spf13/pflag"
+)
+
+const (
+	VERSION string = "0.0.1"
+	Usage   string = `This is kage-viewer, a shader viewer.
+
+Usage: kage-viewer [-vd] [-c <config file>] [-g geom] [-p geom] \
+       -i <image0.png> -i <image1.png> -s <shader.kage>
+
+Options:
+-c --config   <toml file>     Config file to use (optional)
+-i --image    <png file>      Image to load (multiple times allowed, up to 4)
+-s --shader   <kage file>     Shader to run
+-g --geometry <WIDTHxHEIGHT>  Window size
+-p --position <XxY>           Position of image0
+-d --debug    Show debugging output
+-v --version  Show program version
+`
+)
+
+type Config struct {
+	Showversion bool     `koanf:"version"`  // -v
+	Debug       bool     `koanf:"debug"`    // -d
+	Config      string   `koanf:"config"`   // -c
+	Image       []string `koanf:"image"`    // -i
+	Shader      string   `koanf:"shader"`   // -s
+	Geo         string   `koanf:"geometry"` // -g
+	Posision    string   `koanf:"position"` // -p
+
+	X, Y, Width, Height int // feed from -g + -p
+}
+
+func InitConfig() (*Config, error) {
+	var kloader = koanf.New(".")
+
+	// Load default values using the confmap provider.
+	/* not needed yet
+	   if err := kloader.Load(confmap.Provider(map[string]interface{}{
+	   }, "."), nil); err != nil {
+	           return nil, fmt.Errorf("failed to load default values into koanf: %w", err)
+	   }
+	*/
+
+	// setup custom usage
+	flagset := flag.NewFlagSet("config", flag.ContinueOnError)
+	flagset.Usage = func() {
+		fmt.Println(Usage)
+		os.Exit(0)
+	}
+
+	// parse commandline flags
+	flagset.BoolP("version", "v", false, "show program version")
+	flagset.BoolP("debug", "d", false, "enable debug output")
+	flagset.StringP("config", "c", "", "config file")
+	flagset.StringP("geometry", "g", "256x256", "window geometry")
+	flagset.StringP("position", "p", "0x0", "position of shader")
+	flagset.StringArrayP("image", "i", nil, "image file")
+	flagset.StringP("shader", "s", "", "shader file")
+
+	if err := flagset.Parse(os.Args[1:]); err != nil {
+		return nil, fmt.Errorf("failed to parse program arguments: %w", err)
+	}
+
+	// generate a  list of config files to try  to load, including the
+	// one provided via -c, if any
+	var configfiles []string
+
+	configfile, _ := flagset.GetString("config")
+	home, _ := os.UserHomeDir()
+
+	if configfile != "" {
+		configfiles = []string{configfile}
+	} else {
+		configfiles = []string{
+			"/etc/kage-viewer.conf", "/usr/local/etc/kage-viewer.conf", // unix variants
+			filepath.Join(home, ".config", "kage-viewer", "config"),
+			filepath.Join(home, ".kage-viewer"),
+			"kage-viewer.conf",
+		}
+	}
+
+	// Load the config file[s]
+	for _, cfgfile := range configfiles {
+		if path, err := os.Stat(cfgfile); !os.IsNotExist(err) {
+			if !path.IsDir() {
+				if err := kloader.Load(file.Provider(cfgfile), toml.Parser()); err != nil {
+					return nil, fmt.Errorf("error loading config file: %w", err)
+				}
+			}
+		} // else: we ignore the file if it doesn't exists
+	}
+
+	// command line setup
+	if err := kloader.Load(posflag.Provider(flagset, ".", kloader), nil); err != nil {
+		return nil, fmt.Errorf("error loading flags: %w", err)
+	}
+
+	// fetch values
+	conf := &Config{}
+	if err := kloader.Unmarshal("", &conf); err != nil {
+		return nil, fmt.Errorf("error unmarshalling: %w", err)
+	}
+
+	if err := SanitiyCheck(conf); err != nil {
+		return nil, err
+	}
+
+	return conf, nil
+}
+
+func SanitiyCheck(conf *Config) error {
+	if len(conf.Image) < 1 {
+		return fmt.Errorf("at least 1 image must be specified")
+	}
+
+	if conf.Shader == "" {
+		return fmt.Errorf("shader file must be specified")
+	}
+
+	geoerr := "window geometry must be specified as NUMBERxNUMBER, e.g. 32x32"
+
+	geo := strings.Split(conf.Geo, "x")
+	if len(geo) != 2 {
+		return fmt.Errorf(geoerr)
+	}
+
+	w, errw := strconv.Atoi(geo[0])
+	h, errh := strconv.Atoi(geo[1])
+	if errw != nil || errh != nil {
+		return fmt.Errorf(geoerr)
+	}
+
+	conf.Width = w
+	conf.Height = h
+
+	poserr := "shader position must be specified as NUMBERxNUMBER, e.g. 32x32"
+
+	pos := strings.Split(conf.Posision, "x")
+	if len(geo) != 2 {
+		return fmt.Errorf(poserr)
+	}
+
+	x, errx := strconv.Atoi(pos[0])
+	y, erry := strconv.Atoi(pos[1])
+	if errx != nil || erry != nil {
+		return fmt.Errorf(poserr)
+	}
+
+	conf.X = x
+	conf.Y = y
+
+	return nil
+}
+
+func fileExists(filename string) bool {
+	info, err := os.Stat(filename)
+	if os.IsNotExist(err) {
+		return false
+	}
+	return !info.IsDir()
+}