feat(copy): implement copy command

closes #18

src/main/kotlin/com/neo/envmanager/Envm.kt

@@ -47,7 +47,8 @@ class Envm : CliktCommand(
             Rename(),
             Setter(),
             Remove(),
-            Rollback()
+            Rollback(),
+            Copy()
         )
     }
 

src/main/kotlin/com/neo/envmanager/command/Copy.kt

@@ -0,0 +1,28 @@
+package com.neo.envmanager.command
+
+import com.github.ajalt.clikt.parameters.arguments.argument
+import com.neo.envmanager.core.Command
+import com.neo.envmanager.model.Environment
+import com.neo.envmanager.util.extension.requireInstall
+
+class Copy : Command(
+    help = "Copy an environment"
+) {
+    private val tag by argument(
+        help = "Environment tag"
+    )
+
+    private val newTag by argument(
+        help = "New environment tag"
+    )
+
+    override fun run() {
+
+        requireInstall()
+
+        Environment.get(
+            paths.environmentsDir,
+            tag
+        ).copyTo(newTag)
+    }
+}

src/main/kotlin/com/neo/envmanager/command/Rename.kt

@@ -10,8 +10,8 @@ class Rename : Command(
     help = "Rename an environment"
 ) {
 
-    private val oldTag by argument(
-        help = "Old environment tag"
+    private val tag by argument(
+        help = "Environment tag"
     )
 
     private val newTag by argument(
@@ -22,9 +22,12 @@ class Rename : Command(
 
         val config = requireInstall()
 
-        Environment.get(paths.environmentsDir, oldTag).renameTo(newTag)
+        Environment.get(
+            paths.environmentsDir,
+            tag
+        ).renameTo(newTag)
 
-        if (oldTag == config.currentEnv) {
+        if (tag == config.currentEnv) {
             config.update {
                 it.copy(
                     currentEnv = newTag

src/main/kotlin/com/neo/envmanager/model/Environment.kt

@@ -37,6 +37,17 @@ value class Environment(val file: File) {
         return Environment(newFile)
     }
 
+    fun copyTo(tag: String) : Environment {
+
+        val newFile = file.parentFile.resolve(tag.json)
+
+        if (newFile.exists()) throw EnvironmentAlreadyExists(tag)
+
+        file.copyTo(newFile)
+
+        return Environment(newFile)
+    }
+
     fun add(properties:  Map<*, *>) {
         write(read() + properties)
     }