Export options as environment variables (#448)

* Export options as environment variables

Any options from gOpts are available via lf_OPTION environment
variables. For now it works only on booleans, integers and strings (no
array support)

* Do not export some of the options

* Add support for arrays and fix numbers

* Fix comments

* Replace 1 and 0 with true and false

* Export hidden,reverse,dirfirst and sortby options

* Fix comments

* Little fix

* Simplify boolean conversion

app.go

@@ -9,6 +9,8 @@ import (
 	"os/exec"
 	"os/signal"
 	"path/filepath"
+	"reflect"
+	"strconv"
 	"strings"
 	"syscall"
 	"time"
@@ -333,6 +335,85 @@ func (app *app) exportFiles() {
 	exportFiles(currFile, currSelections)
 }
 
+func fieldToString(field reflect.Value) string {
+	kind := field.Kind()
+	var value string
+
+	switch kind {
+	case reflect.Int:
+		value = strconv.Itoa(int(field.Int()))
+	case reflect.Bool:
+		value = strconv.FormatBool(field.Bool())
+	case reflect.Slice:
+		for i := 0; i < field.Len(); i++ {
+			element := field.Index(i)
+
+			if i == 0 {
+				value = fieldToString(element)
+			} else {
+				value += ":" + fieldToString(element)
+			}
+		}
+	default:
+		value = field.String()
+	}
+
+	return value
+}
+
+func (app *app) exportOpts() {
+	e := reflect.ValueOf(&gOpts).Elem()
+
+	for i := 0; i < e.NumField(); i++ {
+		// Get name and prefix it with lf_
+		name := e.Type().Field(i).Name
+		name = fmt.Sprintf("lf_%s", name)
+
+		// Skip maps
+		if name == "lf_keys" || name == "lf_cmdkeys" || name == "lf_cmds" {
+			continue
+		}
+
+		// Get string representation of the value
+		if name == "lf_sortType" {
+			var sortby string
+
+			switch gOpts.sortType.method {
+			case naturalSort:
+				sortby = "natural"
+			case nameSort:
+				sortby = "name"
+			case sizeSort:
+				sortby = "size"
+			case timeSort:
+				sortby = "time"
+			case ctimeSort:
+				sortby = "ctime"
+			case atimeSort:
+				sortby = "atime"
+			case extSort:
+				sortby = "ext"
+			}
+
+			os.Setenv("lf_sortby", sortby)
+
+			reverse := strconv.FormatBool(gOpts.sortType.option&reverseSort != 0)
+			os.Setenv("lf_reverse", reverse)
+
+			hidden := strconv.FormatBool(gOpts.sortType.option&hiddenSort != 0)
+			os.Setenv("lf_hidden", hidden)
+
+			dirfirst := strconv.FormatBool(gOpts.sortType.option&dirfirstSort != 0)
+			os.Setenv("lf_dirfirst", dirfirst)
+		} else {
+			field := e.Field(i)
+			value := fieldToString(field)
+
+			os.Setenv(name, value)
+		}
+	}
+}
+
 func waitKey() error {
 	cmd := pauseCommand()
 
@@ -356,6 +437,7 @@ func waitKey() error {
 //     &       No    Yes    No     No      No      Do nothing
 func (app *app) runShell(s string, args []string, prefix string) {
 	app.exportFiles()
+	app.exportOpts()
 
 	cmd := shellCommand(s, args)