chore: initial commit

config.go

@@ -0,0 +1,152 @@
+package main
+
+import (
+	"errors"
+	"io/fs"
+	"os"
+	"path"
+	"path/filepath"
+	"strings"
+
+	"github.com/spf13/viper"
+)
+
+const currentFileName = "current"
+
+var (
+	configUnmashaled bool
+	cachedConfig     = &config{}
+)
+
+type config struct {
+	Mode    string        `yaml:"mode" json:"mode"`
+	Current currentConfig `yaml:"current" json:"current"`
+	Path    pathsConfig   `yaml:"path" json:"path"`
+}
+
+type currentConfig struct {
+	Version string `yaml:"version" json:"version"`
+	SetBy   string `yaml:"set_by" json:"set_by"`
+}
+
+type pathsConfig struct {
+	Binary   string `yaml:"binary" json:"binary"`
+	Root     string `yaml:"root" json:"root"`
+	Shims    string `yaml:"shims" json:"shims"`
+	Sources  string `yaml:"sources" json:"sources"`
+	Versions string `yaml:"versions" json:"versions"`
+}
+
+func getConfig() (*config, error) {
+	if configUnmashaled {
+		cc, err := getCurrentVersion(cachedConfig)
+		if err != nil {
+			return nil, err
+		}
+
+		cachedConfig.Current = *cc
+
+		return cachedConfig, nil
+	}
+
+	conf := &config{}
+	err := viper.Unmarshal(conf)
+	if err != nil {
+		return nil, err
+	}
+
+	if conf.Mode != "user" && conf.Mode != "system" {
+		return nil, errors.New(`When set EVM_MODE must be "user" or "system"`)
+	}
+
+	conf.Path.Binary, err = os.Executable()
+	if err != nil {
+		return nil, err
+	}
+
+	var homePrefix string
+	switch {
+	case strings.HasPrefix(conf.Path.Root, "$HOME") ||
+		strings.HasPrefix(conf.Path.Root, "$home"):
+		homePrefix = conf.Path.Root[0:5]
+	case strings.HasPrefix(conf.Path.Root, "~"):
+		homePrefix = conf.Path.Root[0:1]
+	}
+
+	if homePrefix != "" {
+		var home string
+		home, err = os.UserHomeDir()
+		if err != nil {
+			return nil, err
+		}
+		conf.Path.Root = filepath.Join(
+			home, strings.TrimPrefix(conf.Path.Root, homePrefix))
+	}
+
+	if strings.HasPrefix(conf.Path.Shims, "$EVM_ROOT") {
+		conf.Path.Shims = filepath.Join(
+			conf.Path.Root, conf.Path.Shims[9:],
+		)
+	} else if !path.IsAbs(conf.Path.Shims) {
+		conf.Path.Shims = filepath.Join(
+			conf.Path.Root, conf.Path.Shims,
+		)
+	}
+
+	if strings.HasPrefix(conf.Path.Sources, "$EVM_ROOT") {
+		conf.Path.Sources = filepath.Join(
+			conf.Path.Root, conf.Path.Sources[9:],
+		)
+	} else if !path.IsAbs(conf.Path.Sources) {
+		conf.Path.Sources = filepath.Join(
+			conf.Path.Root, conf.Path.Sources,
+		)
+	}
+
+	if strings.HasPrefix(conf.Path.Versions, "$EVM_ROOT") {
+		conf.Path.Versions = filepath.Join(
+			conf.Path.Root, conf.Path.Versions[9:],
+		)
+	} else if !path.IsAbs(conf.Path.Versions) {
+		conf.Path.Versions = filepath.Join(
+			conf.Path.Root, conf.Path.Versions,
+		)
+	}
+
+	cc, err := getCurrentVersion(conf)
+	if err != nil {
+		return nil, err
+	}
+
+	conf.Current = *cc
+	cachedConfig = conf
+
+	return cachedConfig, nil
+}
+
+func getCurrentVersion(conf *config) (*currentConfig, error) {
+	cc := &currentConfig{}
+
+	if v := os.Getenv("EVM_VERSION"); v != "" {
+		cc.Version = strings.TrimSpace(v)
+		cc.SetBy = "EVM_VERSION environment variable"
+
+		return cc, nil
+	}
+
+	currentFile := filepath.Join(conf.Path.Root, currentFileName)
+	b, err := os.ReadFile(currentFile)
+	if err != nil {
+		if errors.Is(err, fs.ErrNotExist) {
+			return cc, nil
+		}
+		return nil, err
+	}
+
+	if len(b) > 0 {
+		cc.Version = strings.TrimSpace(string(b))
+		cc.SetBy = currentFile
+	}
+
+	return cc, nil
+}