Adds log rotation, config file support, and refactoring. Colorschemes are self-registered. Merge remote-tracking branch 'jrswab/configFile111' into config_file; drastically refactored, and am not sure how much original code from the patch was used.

17 files changed, 472 insertions, 228 deletions

diff --git a/CHANGELOG.md b/CHANGELOG.md
index f8328b4..32bd5e4 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -15,10 +15,19 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [3.3.0] - 
 
-- Changed: Logs are now rotated. Settings are currently hard-coded at 4 files of 5MB
+- Added: Logs are now rotated. Settings are currently hard-coded at 4 files of 5MB
   each, so logs shouldn't take up more than 20MB.  I'm going to see how many
   complain about wanting to configure these settings before I add code to do
   that.
+- Added: Config file support. \$XDG_CONFIG_HOME/gotop/gotop.conf can now
+  contain any field in Config.  Syntax is simply KEY=VALUE.  Values in config
+  file are overridden by command-line arguments (although, there's a weakness
+  in that there's no way to disable boolean fields enabled in the config).
+- Changed: Colorscheme registration is changed to be less hard-coded.
+  Colorschemes can now be created and added to the repo, without having to also
+  add hard-coded references elsewhere.
+- Changed: Minor code refactoring to support Config file changes has resulted
+  in better isolation.
 
 ## [3.2.0] - 2020-02-14
 
diff --git a/README.md b/README.md
index 0903624..a3ff80c 100644
--- a/README.md
+++ b/README.md
@@ -149,14 +149,14 @@ build massive edifices, you're in for disappointment.
 ### CLI Options
 
 `-c`, `--color=NAME` Set a colorscheme.  
-`-m`, `--minimal` Only show CPU, Mem and Process widgets.  
+`-m`, `--minimal` Only show CPU, Mem and Process widgets.  (DEPRECATED for `-l minimal`)
 `-r`, `--rate=RATE` Number of times per second to update CPU and Mem widgets [default: 1].  
 `-V`, `--version` Print version and exit.  
 `-p`, `--percpu` Show each CPU in the CPU widget.  
 `-a`, `--averagecpu` Show average CPU in the CPU widget.  
 `-f`, `--fahrenheit` Show temperatures in fahrenheit.  
 `-s`, `--statusbar` Show a statusbar with the time.  
-`-b`, `--battery` Show battery level widget (`minimal` turns off). [preview](./assets/screenshots/battery.png)  
+`-b`, `--battery` Show battery level widget (`minimal` turns off). [preview](./assets/screenshots/battery.png)  (DEPRECATED for `-l battery`)
 `-i`, `--interface=NAME` Select network interface [default: all].
 `-l`, `--layout=NAME` Choose a layout. gotop searches for a file by NAME in \$XDG_CONFIG_HOME/gotop, then relative to the current path. "-" reads a layout from stdin, allowing for simple, one-off layouts such as `echo net | gotop -l -`
 
diff --git a/cmd/gotop/main.go b/cmd/gotop/main.go
index 3249cf2..1e9f4f4 100644
--- a/cmd/gotop/main.go
+++ b/cmd/gotop/main.go
@@ -1,9 +1,8 @@
 package main
 
 import (
-	"encoding/json"
 	"fmt"
-	"io/ioutil"
+	"io"
 	"log"
 	"os"
 	"os/signal"
@@ -42,7 +41,7 @@ var (
 	stderrLogger = log.New(os.Stderr, "", 0)
 )
 
-func parseArgs() (gotop.Config, error) {
+func parseArgs(conf *gotop.Config) error {
 	usage := `
 Usage: gotop [options]
 
@@ -75,133 +74,65 @@ Colorschemes:
   vice
 `
 
-	ld := utils.GetLogDir(appName)
-	cd := utils.GetConfigDir(appName)
-	conf = gotop.Config{
-		ConfigDir:            cd,
-		LogDir:               ld,
-		LogFile:              "errors.log",
-		GraphHorizontalScale: 7,
-		HelpVisible:          false,
-		Colorscheme:          colorschemes.Default,
-		UpdateInterval:       time.Second,
-		AverageLoad:          false,
-		PercpuLoad:           false,
-		TempScale:            w.Celsius,
-		Statusbar:            false,
-		NetInterface:         w.NET_INTERFACE_ALL,
-		MaxLogSize:           5000000,
+	var err error
+	conf.Colorscheme, err = colorschemes.FromName(conf.ConfigDir, "default")
+	if err != nil {
+		return err
 	}
 
 	args, err := docopt.ParseArgs(usage, os.Args[1:], version)
 	if err != nil {
-		return conf, err
+		return err
 	}
 
 	if val, _ := args["--layout"]; val != nil {
-		s := val.(string)
-		switch s {
-		case "-":
-			conf.Layout = os.Stdin
-		case "default":
-			conf.Layout = strings.NewReader(defaultUI)
-		case "minimal":
-			conf.Layout = strings.NewReader(minimalUI)
-		case "battery":
-			conf.Layout = strings.NewReader(batteryUI)
-		default:
-			fp := filepath.Join(cd, s)
-			conf.Layout, err = os.Open(fp)
-			if err != nil {
-				conf.Layout, err = os.Open(s)
-				if err != nil {
-					stderrLogger.Fatalf("Unable to open layout file %s or ./%s", fp, s)
-				}
-			}
-		}
-	} else {
-		conf.Layout = strings.NewReader(defaultUI)
+		conf.Layout = val.(string)
 	}
-
 	if val, _ := args["--color"]; val != nil {
-		cs, err := handleColorscheme(val.(string))
+		cs, err := colorschemes.FromName(conf.ConfigDir, val.(string))
 		if err != nil {
-			return conf, err
+			return err
 		}
 		conf.Colorscheme = cs
 	}
-	conf.AverageLoad, _ = args["--averagecpu"].(bool)
-	conf.PercpuLoad, _ = args["--percpu"].(bool)
-	statusbar, _ = args["--statusbar"].(bool)
-
-	if args["--battery"].(bool) {
-		log.Printf("BATTERY %s", batteryUI)
-		conf.Layout = strings.NewReader(batteryUI)
+	if args["--averagecpu"].(bool) {
+		conf.AverageLoad, _ = args["--averagecpu"].(bool)
 	}
-	if args["--minimal"].(bool) {
-		conf.Layout = strings.NewReader(minimalUI)
+	if args["--percpu"].(bool) {
+		conf.PercpuLoad, _ = args["--percpu"].(bool)
 	}
-	rateStr, _ := args["--rate"].(string)
-	rate, err := strconv.ParseFloat(rateStr, 64)
-	if err != nil {
-		return conf, fmt.Errorf("invalid rate parameter")
+	if args["--statusbar"].(bool) {
+		statusbar, _ = args["--statusbar"].(bool)
 	}
-	if rate < 1 {
-		conf.UpdateInterval = time.Second * time.Duration(1/rate)
-	} else {
-		conf.UpdateInterval = time.Second / time.Duration(rate)
+	if args["--battery"].(bool) {
+		conf.Layout = "battery"
 	}
-	fahrenheit, _ := args["--fahrenheit"].(bool)
-	if fahrenheit {
-		conf.TempScale = w.Fahrenheit
+	if args["--minimal"].(bool) {
+		conf.Layout = "minimal"
 	}
-	conf.NetInterface, _ = args["--interface"].(string)
-
-	return conf, nil
-}
-
-func handleColorscheme(c string) (colorschemes.Colorscheme, error) {
-	var cs colorschemes.Colorscheme
-	switch c {
-	case "default":
-		cs = colorschemes.Default
-	case "solarized":
-		cs = colorschemes.Solarized
-	case "solarized16-light":
-		cs = colorschemes.Solarized16Light
-	case "solarized16-dark":
-		cs = colorschemes.Solarized16Dark
-	case "monokai":
-		cs = colorschemes.Monokai
-	case "vice":
-		cs = colorschemes.Vice
-	case "default-dark":
-		cs = colorschemes.DefaultDark
-	case "nord":
-		cs = colorschemes.Nord
-	default:
-		custom, err := getCustomColorscheme(conf, c)
+	if val, _ := args["--statusbar"]; val != nil {
+		rateStr, _ := args["--rate"].(string)
+		rate, err := strconv.ParseFloat(rateStr, 64)
 		if err != nil {
-			return cs, err
+			return fmt.Errorf("invalid rate parameter")
+		}
+		if rate < 1 {
+			conf.UpdateInterval = time.Second * time.Duration(1/rate)
+		} else {
+			conf.UpdateInterval = time.Second / time.Duration(rate)
 		}
-		cs = custom
 	}
-	return cs, nil
-}
-
-// getCustomColorscheme	tries to read a custom json colorscheme from <configDir>/<name>.json
-func getCustomColorscheme(c gotop.Config, name string) (colorschemes.Colorscheme, error) {
-	var cs colorschemes.Colorscheme
-	filePath := filepath.Join(c.ConfigDir, name+".json")
-	dat, err := ioutil.ReadFile(filePath)
-	if err != nil {
-		return cs, fmt.Errorf("failed to read colorscheme file: %v", err)
+	if val, _ := args["--fahrenheit"]; val != nil {
+		fahrenheit, _ := val.(bool)
+		if fahrenheit {
+			conf.TempScale = w.Fahrenheit
+		}
 	}
-	err = json.Unmarshal(dat, &cs)
-	if err != nil {
-		return cs, fmt.Errorf("failed to parse colorscheme file: %v", err)
+	if val, _ := args["--interface"]; val != nil {
+		conf.NetInterface, _ = args["--interface"].(string)
 	}
-	return cs, nil
+
+	return nil
 }
 
 func setDefaultTermuiColors(c gotop.Config) {
@@ -388,8 +319,40 @@ func eventLoop(c gotop.Config, grid *layout.MyGrid) {
 	}
 }
 
+func makeConfig() gotop.Config {
+	ld := utils.GetLogDir(appName)
+	cd := utils.GetConfigDir(appName)
+	conf = gotop.Config{
+		ConfigDir:            cd,
+		LogDir:               ld,
+		LogFile:              "errors.log",
+		GraphHorizontalScale: 7,
+		HelpVisible:          false,
+		UpdateInterval:       time.Second,
+		AverageLoad:          false,
+		PercpuLoad:           false,
+		TempScale:            w.Celsius,
+		Statusbar:            false,
+		NetInterface:         w.NET_INTERFACE_ALL,
+		MaxLogSize:           5000000,
+		Layout:               "default",
+	}
+	return conf
+}
+
 func main() {
-	conf, err := parseArgs()
+	// Set up default config
+	conf := makeConfig()
+	// Parse the config file
+	cfn := filepath.Join(conf.ConfigDir, "gotop.conf")
+	if cf, err := os.Open(cfn); err == nil {
+		err := gotop.Parse(cf, &conf)
+		if err != nil {
+			stderrLogger.Fatalf("error parsing config file %v", err)
+		}
+	}
+	// Override with command line arguments
+	err := parseArgs(&conf)
 	if err != nil {
 		stderrLogger.Fatalf("failed to parse cli args: %v", err)
 	}
@@ -411,7 +374,8 @@ func main() {
 		bar = w.NewStatusBar()
 	}
 
-	ly := layout.ParseLayout(conf.Layout)
+	lstream := getLayout(conf)
+	ly := layout.ParseLayout(lstream)
 	grid, err := layout.Layout(ly, conf)
 	if err != nil {
 		stderrLogger.Fatalf("failed to initialize termui: %v", err)
@@ -433,3 +397,27 @@ func main() {
 
 	eventLoop(conf, grid)
 }
+
+func getLayout(conf gotop.Config) io.Reader {
+	switch conf.Layout {
+	case "-":
+		return os.Stdin
+	case "default":
+		return strings.NewReader(defaultUI)
+	case "minimal":
+		return strings.NewReader(minimalUI)
+	case "battery":
+		return strings.NewReader(batteryUI)
+	default:
+		log.Printf("layout = %s", conf.Layout)
+		fp := filepath.Join(conf.ConfigDir, conf.Layout)
+		fin, err := os.Open(fp)
+		if err != nil {
+			fin, err = os.Open(conf.Layout)
+			if err != nil {
+				log.Fatalf("Unable to open layout file %s or ./%s", fp, conf.Layout)
+			}
+		}
+		return fin
+	}
+}
diff --git a/colorschemes/default.go b/colorschemes/default.go
index de65c22..dc6c6b2 100644
--- a/colorschemes/default.go
+++ b/colorschemes/default.go
@@ -1,25 +1,27 @@
 package colorschemes
 
-var Default = Colorscheme{
-	Fg: 7,
-	Bg: -1,
+func init() {
+	register("default", Colorscheme{
+		Fg: 7,
+		Bg: -1,
 
-	BorderLabel: 7,
-	BorderLine:  6,
+		BorderLabel: 7,
+		BorderLine:  6,
 
-	CPULines: []int{4, 3, 2, 1, 5, 6, 7, 8},
+		CPULines: []int{4, 3, 2, 1, 5, 6, 7, 8},
 
-	BattLines: []int{4, 3, 2, 1, 5, 6, 7, 8},
+		BattLines: []int{4, 3, 2, 1, 5, 6, 7, 8},
 
-	MainMem: 5,
-	SwapMem: 11,
+		MainMem: 5,
+		SwapMem: 11,
 
-	ProcCursor: 4,
+		ProcCursor: 4,
 
-	Sparkline: 4,
+		Sparkline: 4,
 
-	DiskBar: 7,
+		DiskBar: 7,
 
-	TempLow:  2,
-	TempHigh: 1,
+		TempLow:  2,
+		TempHigh: 1,
+	})
 }
diff --git a/colorschemes/default_dark.go b/colorschemes/default_dark.go
index 6070985..7ddb5f7 100644
--- a/colorschemes/default_dark.go
+++ b/colorschemes/default_dark.go
@@ -1,25 +1,27 @@
 package colorschemes
 
-var DefaultDark = Colorscheme{
-	Fg: 235,
-	Bg: -1,
+func init() {
+	register("defaultdark", Colorscheme{
+		Fg: 235,
+		Bg: -1,
 
-	BorderLabel: 235,
-	BorderLine:  6,
+		BorderLabel: 235,
+		BorderLine:  6,
 
-	CPULines: []int{4, 3, 2, 1, 5, 6, 7, 8},
+		CPULines: []int{4, 3, 2, 1, 5, 6, 7, 8},
 
-	BattLines: []int{4, 3, 2, 1, 5, 6, 7, 8},
+		BattLines: []int{4, 3, 2, 1, 5, 6, 7, 8},
 
-	MainMem: 5,
-	SwapMem: 3,
+		MainMem: 5,
+		SwapMem: 3,
 
-	ProcCursor: 33,
+		ProcCursor: 33,
 
-	Sparkline: 4,
+		Sparkline: 4,
 
-	DiskBar: 252,
+		DiskBar: 252,
 
-	TempLow:  2,
-	TempHigh: 1,
+		TempLow:  2,
+		TempHigh: 1,
+	})
 }
diff --git a/colorschemes/monokai.go b/colorschemes/monokai.go
index 445f054..cd0471c 100644
--- a/colorschemes/monokai.go
+++ b/colorschemes/monokai.go
@@ -1,25 +1,27 @@
 package colorschemes
 
-var Monokai = Colorscheme{
-	Fg: 249,
-	Bg: -1,
+func init() {
+	register("monokai", Colorscheme{
+		Fg: 249,
+		Bg: -1,
 
-	BorderLabel: 249,
-	BorderLine:  239,
+		BorderLabel: 249,
+		BorderLine:  239,
 
-	CPULines: []int{81, 70, 208, 197, 249, 141, 221, 186},
+		CPULines: []int{81, 70, 208, 197, 249, 141, 221, 186},
 
-	BattLines: []int{81, 70, 208, 197, 249, 141, 221, 186},
+		BattLines: []int{81, 70, 208, 197, 249, 141, 221, 186},
 
-	MainMem: 208,
-	SwapMem: 186,
+		MainMem: 208,
+		SwapMem: 186,
 
-	ProcCursor: 197,
+		ProcCursor: 197,
 
-	Sparkline: 81,
+		Sparkline: 81,
 
-	DiskBar: 102,
+		DiskBar: 102,
 
-	TempLow:  70,
-	TempHigh: 208,
+		TempLow:  70,
+		TempHigh: 208,
+	})
 }
diff --git a/colorschemes/nord.go b/colorschemes/nord.go
index f493e40..b6d4b50 100644
--- a/colorschemes/nord.go
+++ b/colorschemes/nord.go
@@ -11,28 +11,30 @@
 
 package colorschemes
 
-var Nord = Colorscheme{
-	Name:   "A Nord Approximation",
-	Author: "@jrswab",
-	Fg:     254, // lightest
-	Bg:     -1,
+func init() {
+	register("nord", Colorscheme{
+		Name:   "A Nord Approximation",
+		Author: "@jrswab",
+		Fg:     254, // lightest
+		Bg:     -1,
 
-	BorderLabel: 254,
-	BorderLine:  96, // Purple
+		BorderLabel: 254,
+		BorderLine:  96, // Purple
 
-	CPULines: []int{4, 3, 2, 1, 5, 6, 7, 8},
+		CPULines: []int{4, 3, 2, 1, 5, 6, 7, 8},
 
-	BattLines: []int{4, 3, 2, 1, 5, 6, 7, 8},
+		BattLines: []int{4, 3, 2, 1, 5, 6, 7, 8},
 
-	MainMem: 172, // Orange
-	SwapMem: 221, // yellow
+		MainMem: 172, // Orange
+		SwapMem: 221, // yellow
 
-	ProcCursor: 31, // blue (nord9)
+		ProcCursor: 31, // blue (nord9)
 
-	Sparkline: 31,
+		Sparkline: 31,
 
-	DiskBar: 254,
+		DiskBar: 254,
 
-	TempLow:  64,  // green
-	TempHigh: 167, // red
+		TempLow:  64,  // green
+		TempHigh: 167, // red
+	})
 }
diff --git a/colorschemes/registry.go b/colorschemes/registry.go
new file mode 100644
index 0000000..97e2bb0
--- /dev/null
+++ b/colorschemes/registry.go
@@ -0,0 +1,43 @@
+package colorschemes
+
+import (
+	"encoding/json"
+	"fmt"
+	"io/ioutil"
+	"path/filepath"
+)
+
+var registry map[string]Colorscheme
+
+func FromName(confDir string, c string) (Colorscheme, error) {
+	cs, ok := registry[c]
+	if !ok {
+		cs, err := getCustomColorscheme(confDir, c)
+		if err != nil {
+			return cs, err
+		}
+	}
+	return cs, nil
+}
+
+func register(name string, c Colorscheme) {
+	if registry == nil {
+		registry = make(map[string]Colorscheme)
+	}
+	registry[name] = c
+}
+
+// getCustomColorscheme	tries to read a custom json colorscheme from <configDir>/<name>.json
+func getCustomColorscheme(confDir string, name string) (Colorscheme, error) {
+	var cs Colorscheme
+	filePath := filepath.Join(confDir, name+".json")
+	dat, err := ioutil.ReadFile(filePath)
+	if err != nil {
+		return cs, fmt.Errorf("failed to read colorscheme file: %v", err)
+	}
+	err = json.Unmarshal(dat, &cs)
+	if err != nil {
+		return cs, fmt.Errorf("failed to parse colorscheme file: %v", err)
+	}
+	return cs, nil
+}
diff --git a/colorschemes/solarized.go b/colorschemes/solarized.go
index 5968310..48d67b0 100644
--- a/colorschemes/solarized.go
+++ b/colorschemes/solarized.go
@@ -3,26 +3,28 @@ package colorschemes
 // This is a neutral version of the Solarized 256-color palette. The exception
 // is that the one grey color uses the average of base0 and base00, which are
 // already middle of the road.
-var Solarized = Colorscheme{
-	Fg: -1,
-	Bg: -1,
+func init() {
+	register("solarized", Colorscheme{
+		Fg: -1,
+		Bg: -1,
 
-	BorderLabel: -1,
-	BorderLine:  37,
+		BorderLabel: -1,
+		BorderLine:  37,
 
-	CPULines: []int{61, 33, 37, 64, 125, 160, 166, 136},
+		CPULines: []int{61, 33, 37, 64, 125, 160, 166, 136},
 
-	BattLines: []int{61, 33, 37, 64, 125, 160, 166, 136},
+		BattLines: []int{61, 33, 37, 64, 125, 160, 166, 136},
 
-	MainMem: 125,
-	SwapMem: 166,
+		MainMem: 125,
+		SwapMem: 166,
 
-	ProcCursor: 136,
+		ProcCursor: 136,
 
-	Sparkline: 33,
+		Sparkline: 33,
 
-	DiskBar: 243,
+		DiskBar: 243,
 
-	TempLow:  64,
-	TempHigh: 160,
+		TempLow:  64,
+		TempHigh: 160,
+	})
 }
diff --git a/colorschemes/solarized16-dark.go b/colorschemes/solarized16-dark.go
index f8cdab7..202dbab 100644
--- a/colorschemes/solarized16-dark.go
+++ b/colorschemes/solarized16-dark.go
@@ -2,26 +2,28 @@ package colorschemes
 
 // This scheme assumes the terminal already uses Solarized. Only DiskBar is
 // different between dark/light.
-var Solarized16Dark = Colorscheme{
-	Fg: -1,
-	Bg: -1,
+func init() {
+	register("solarized16dark", Colorscheme{
+		Fg: -1,
+		Bg: -1,
 
-	BorderLabel: -1,
-	BorderLine:  6,
+		BorderLabel: -1,
+		BorderLine:  6,
 
-	CPULines: []int{13, 4, 6, 2, 5, 1, 9, 3},
+		CPULines: []int{13, 4, 6, 2, 5, 1, 9, 3},
 
-	BattLines: []int{13, 4, 6, 2, 5, 1, 9, 3},
+		BattLines: []int{13, 4, 6, 2, 5, 1, 9, 3},
 
-	MainMem: 5,
-	SwapMem: 9,
+		MainMem: 5,
+		SwapMem: 9,
 
-	ProcCursor: 4,
+		ProcCursor: 4,
 
-	Sparkline: 4,
+		Sparkline: 4,
 
-	DiskBar: 12, // base0
+		DiskBar: 12, // base0
 
-	TempLow:  2,
-	TempHigh: 1,
+		TempLow:  2,
+		TempHigh: 1,
+	})
 }
diff --git a/colorschemes/solarized16-light.go b/colorschemes/solarized16-light.go
index 8426a95..351fe4e 100644
--- a/colorschemes/solarized16-light.go
+++ b/colorschemes/solarized16-light.go
@@ -2,26 +2,28 @@ package colorschemes
 
 // This scheme assumes the terminal already uses Solarized. Only DiskBar is
 // different between dark/light.
-var Solarized16Light = Colorscheme{
-	Fg: -1,
-	Bg: -1,
+func init() {
+	register("solarized16light", Colorscheme{
+		Fg: -1,
+		Bg: -1,
 
-	BorderLabel: -1,
-	BorderLine:  6,
+		BorderLabel: -1,
+		BorderLine:  6,
 
-	CPULines: []int{13, 4, 6, 2, 5, 1, 9, 3},
+		CPULines: []int{13, 4, 6, 2, 5, 1, 9, 3},
 
-	BattLines: []int{13, 4, 6, 2, 5, 1, 9, 3},
+		BattLines: []int{13, 4, 6, 2, 5, 1, 9, 3},
 
-	MainMem: 5,
-	SwapMem: 9,
+		MainMem: 5,
+		SwapMem: 9,
 
-	ProcCursor: 4,
+		ProcCursor: 4,
 
-	Sparkline: 4,
+		Sparkline: 4,
 
-	DiskBar: 11, // base00
+		DiskBar: 11, // base00
 
-	TempLow:  2,
-	TempHigh: 1,
+		TempLow:  2,
+		TempHigh: 1,
+	})
 }
diff --git a/colorschemes/vice.go b/colorschemes/vice.go
index 23fa02a..8bd2545 100644
--- a/colorschemes/vice.go
+++ b/colorschemes/vice.go
@@ -1,25 +1,27 @@
 package colorschemes
 
-var Vice = Colorscheme{
-	Fg: 231,
-	Bg: -1,
+func init() {
+	register("vice", Colorscheme{
+		Fg: 231,
+		Bg: -1,
 
-	BorderLabel: 123,
-	BorderLine:  102,
+		BorderLabel: 123,
+		BorderLine:  102,
 
-	CPULines: []int{212, 218, 123, 159, 229, 158, 183, 146},
+		CPULines: []int{212, 218, 123, 159, 229, 158, 183, 146},
 
-	BattLines: []int{212, 218, 123, 159, 229, 158, 183, 146},
+		BattLines: []int{212, 218, 123, 159, 229, 158, 183, 146},
 
-	MainMem: 201,
-	SwapMem: 97,
+		MainMem: 201,
+		SwapMem: 97,
 
-	ProcCursor: 159,
+		ProcCursor: 159,
 
-	Sparkline: 183,
+		Sparkline: 183,
 
-	DiskBar: 158,
+		DiskBar: 158,
 
-	TempLow:  49,
-	TempHigh: 197,
+		TempLow:  49,
+		TempHigh: 197,
+	})
 }
diff --git a/config.go b/config.go
index c215fac..0cd9e58 100644
--- a/config.go
+++ b/config.go
@@ -1,7 +1,11 @@
 package gotop
 
 import (
+	"bufio"
+	"fmt"
 	"io"
+	"strconv"
+	"strings"
 	"time"
 
 	"github.com/xxxserxxx/gotop/colorschemes"
@@ -29,9 +33,92 @@ type Config struct {
 	UpdateInterval time.Duration
 	AverageLoad    bool
 	PercpuLoad     bool
-	TempScale      widgets.TempScale
 	Statusbar      bool
+	TempScale      widgets.TempScale
 	NetInterface   string
-	Layout         io.Reader
+	Layout         string
 	MaxLogSize     int64
 }
+
+func Parse(in io.Reader, conf *Config) error {
+	r := bufio.NewScanner(in)
+	var lineNo int
+	for r.Scan() {
+		l := strings.TrimSpace(r.Text())
+		kv := strings.Split(l, "=")
+		if len(kv) != 2 {
+			return fmt.Errorf("bad config file syntax; should be KEY=VALUE, was %s", l)
+		}
+		key := strings.ToLower(kv[0])
+		switch key {
+		default:
+			return fmt.Errorf("invalid config option %s", key)
+		case "configdir":
+			conf.ConfigDir = kv[1]
+		case "logdir":
+			conf.LogDir = kv[1]
+		case "logfile":
+			conf.LogFile = kv[1]
+		case "graphhorizontalscale":
+			iv, err := strconv.Atoi(kv[1])
+			if err != nil {
+				return err
+			}
+			conf.GraphHorizontalScale = iv
+		case "helpvisible":
+			bv, err := strconv.ParseBool(kv[1])
+			if err != nil {
+				return fmt.Errorf("line %d: %v", lineNo, err)
+			}
+			conf.HelpVisible = bv
+		case "colorscheme":
+			cs, err := colorschemes.FromName(conf.ConfigDir, kv[1])
+			if err != nil {
+				return fmt.Errorf("line %d: %v", lineNo, err)
+			}
+			conf.Colorscheme = cs
+		case "updateinterval":
+			iv, err := strconv.Atoi(kv[1])
+			if err != nil {
+				return err
+			}
+			conf.UpdateInterval = time.Duration(iv)
+		case "averagecpu":
+			bv, err := strconv.ParseBool(kv[1])
+			if err != nil {
+				return fmt.Errorf("line %d: %v", lineNo, err)
+			}
+			conf.AverageLoad = bv
+		case "percpuload":
+			bv, err := strconv.ParseBool(kv[1])
+			if err != nil {
+				return fmt.Errorf("line %d: %v", lineNo, err)
+			}
+			conf.PercpuLoad = bv
+		case "tempscale":
+			iv, err := strconv.Atoi(kv[1])
+			if err != nil {
+				return err
+			}
+			conf.TempScale = widgets.TempScale(iv)
+		case "statusbar":
+			bv, err := strconv.ParseBool(kv[1])
+			if err != nil {
+				return fmt.Errorf("line %d: %v", lineNo, err)
+			}
+			conf.Statusbar = bv
+		case "netinterface":
+			conf.NetInterface = kv[1]
+		case "layout":
+			conf.Layout = kv[1]
+		case "maxlogsize":
+			iv, err := strconv.Atoi(kv[1])
+			if err != nil {
+				return err
+			}
+			conf.MaxLogSize = int64(iv)
+		}
+	}
+
+	return nil
+}
diff --git a/config.json b/config.json
new file mode 100644
index 0000000..832e015
--- /dev/null
+++ b/config.json
@@ -0,0 +1,11 @@
+{
+  "colorscheme": "default",
+  "updateInterval": 1,
+  "minimalMode": false,
+  "averageLoad": false,
+  "percpuLoad": false,
+  "isFahrenheit": false,
+  "battery": false,
+  "statusbar": false,
+  "netInterface": "NET_INTERFACE_ALL"
+}
diff --git a/config_test.go b/config_test.go
new file mode 100644
index 0000000..329ef75
--- /dev/null
+++ b/config_test.go
@@ -0,0 +1,87 @@
+package gotop
+
+import (
+	"strings"
+	"testing"
+	"time"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/xxxserxxx/gotop/widgets"
+)
+
+func TestParse(t *testing.T) {
+	tests := []struct {
+		i string
+		f func(c Config, e error)
+	}{
+		{
+			i: "logdir",
+			f: func(c Config, e error) {
+				assert.Error(t, e, "invalid config syntax")
+			},
+		},
+		{
+			i: "logdir=foo=bar",
+			f: func(c Config, e error) {
+				assert.NotNil(t, e)
+			},
+		},
+		{
+			i: "foo=bar",
+			f: func(c Config, e error) {
+				assert.NotNil(t, e)
+			},
+		},
+		{
+			i: "configdir=abc\nlogdir=bar\nlogfile=errors",
+			f: func(c Config, e error) {
+				assert.Nil(t, e, "unexpected error")
+				assert.Equal(t, "abc", c.ConfigDir)
+				assert.Equal(t, "bar", c.LogDir)
+				assert.Equal(t, "errors", c.LogFile)
+			},
+		},
+		{
+			i: "CONFIGDIR=abc\nloGdir=bar\nlogFILe=errors",
+			f: func(c Config, e error) {
+				assert.Nil(t, e, "unexpected error")
+				assert.Equal(t, "abc", c.ConfigDir)
+				assert.Equal(t, "bar", c.LogDir)
+				assert.Equal(t, "errors", c.LogFile)
+			},
+		},
+		{
+			i: "graphhorizontalscale=a",
+			f: func(c Config, e error) {
+				assert.Error(t, e, "expected invalid value for graphhorizontalscale")
+			},
+		},
+		{
+			i: "helpvisible=a",
+			f: func(c Config, e error) {
+				assert.Error(t, e, "expected invalid value for helpvisible")
+			},
+		},
+		{
+			i: "helpvisible=true\nupdateinterval=30\naveragecpu=true\nPerCPULoad=true\ntempscale=100\nstatusbar=true\nnetinterface=eth0\nlayout=minimal\nmaxlogsize=200",
+			f: func(c Config, e error) {
+				assert.Nil(t, e, "unexpected error")
+				assert.Equal(t, true, c.HelpVisible)
+				assert.Equal(t, time.Duration(30), c.UpdateInterval)
+				assert.Equal(t, true, c.AverageLoad)
+				assert.Equal(t, true, c.PercpuLoad)
+				assert.Equal(t, widgets.TempScale(100), c.TempScale)
+				assert.Equal(t, true, c.Statusbar)
+				assert.Equal(t, "eth0", c.NetInterface)
+				assert.Equal(t, "minimal", c.Layout)
+				assert.Equal(t, int64(200), c.MaxLogSize)
+			},
+		},
+	}
+	for _, tc := range tests {
+		in := strings.NewReader(tc.i)
+		c := Config{}
+		e := Parse(in, &c)
+		tc.f(c, e)
+	}
+}
diff --git a/go.mod b/go.mod
index e96c9b4..56c0e5d 100644
--- a/go.mod
+++ b/go.mod
@@ -8,6 +8,7 @@ require (
 	github.com/gizak/termui/v3 v3.0.0
 	github.com/go-ole/go-ole v1.2.4 // indirect
 	github.com/mattn/go-runewidth v0.0.4
+	github.com/mitchellh/go-wordwrap v1.0.0 // indirect
 	github.com/shirou/gopsutil v2.18.11+incompatible
 	github.com/shirou/w32 v0.0.0-20160930032740-bb4de0191aa4 // indirect
 	github.com/stretchr/testify v1.4.0
diff --git a/go.sum b/go.sum
index f2046de..6106028 100644
--- a/go.sum
+++ b/go.sum
@@ -26,6 +26,8 @@ github.com/mattn/go-runewidth v0.0.4 h1:2BvfKmzob6Bmd4YsL0zygOqfdFnK7GR4QL06Do4/
 github.com/mattn/go-runewidth v0.0.4/go.mod h1:LwmH8dsx7+W8Uxz3IHJYH5QSwggIsqBzpuz5H//U1FU=
 github.com/mitchellh/go-wordwrap v0.0.0-20150314170334-ad45545899c7 h1:DpOJ2HYzCv8LZP15IdmG+YdwD2luVPHITV96TkirNBM=
 github.com/mitchellh/go-wordwrap v0.0.0-20150314170334-ad45545899c7/go.mod h1:ZXFpozHsX6DPmq2I0TCekCxypsnAUbP2oI0UX1GXzOo=
+github.com/mitchellh/go-wordwrap v1.0.0 h1:6GlHJ/LTGMrIJbwgdqdl2eEH8o+Exx/0m8ir9Gns0u4=
+github.com/mitchellh/go-wordwrap v1.0.0/go.mod h1:ZXFpozHsX6DPmq2I0TCekCxypsnAUbP2oI0UX1GXzOo=
 github.com/nsf/termbox-go v0.0.0-20190121233118-02980233997d h1:x3S6kxmy49zXVVyhcnrFqxvNVCBPb2KZ9hV2RBdS840=
 github.com/nsf/termbox-go v0.0.0-20190121233118-02980233997d/go.mod h1:IuKpRQcYE1Tfu+oAQqaLisqDeXgjyyltCfsaoYN18NQ=
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=