Add basic library code to manage projects, activities and times.

lib/common.go

@@ -0,0 +1,39 @@
+// Package lib provides routines for creating and reading data files as defined by the specification.
+package lib
+
+import (
+	"os"
+	"os/exec"
+	"path/filepath"
+)
+
+// dataDir holds the configured directory to read/write data from/to.
+var dataDir string
+
+// SetDataDir sets the global directory to read/write data from/to. It is typically called once at application start.
+func SetDataDir(directory string) {
+	dataDir = directory
+}
+
+// getDataDir gets the global directory to read/write data from/to for a schema entity.
+func getDataDir(entity string) (string, error) {
+	if dataDir != "" {
+		return filepath.Join(dataDir, entity), nil
+	}
+
+	home, homeErr := os.UserHomeDir()
+	if homeErr != nil {
+		return "", homeErr
+	}
+
+	return filepath.Join(home, ".protime", entity), nil
+}
+
+// newUUID creates a new UUID for an entity instance using the OS command `uuidgen`.
+func newUUID() (string, error) {
+	out, err := exec.Command("uuidgen").Output()
+	if err != nil {
+		return "", err
+	}
+	return string(out[:len(out)-1]), nil
+}