Add Env support to placeholders

common/src/commonMain/kotlin/com/artemchep/keyguard/common/service/placeholder/impl/EnvironmentPlaceholder.kt

@@ -0,0 +1,25 @@
+package com.artemchep.keyguard.common.service.placeholder.impl
+
+import com.artemchep.keyguard.common.io.IO
+import com.artemchep.keyguard.common.io.ioEffect
+import com.artemchep.keyguard.common.service.placeholder.Placeholder
+
+class EnvironmentPlaceholder(
+) : Placeholder {
+    private val regex = "^%(.+)%$".toRegex()
+
+    override fun get(
+        key: String,
+    ): IO<String?>? = kotlin.run {
+        val result = regex.matchEntire(key)
+        if (result != null) {
+            ioEffect {
+                val variable = result.groupValues[1]
+                System.getenv(variable)
+            }
+        } else {
+            // unknown
+            null
+        }
+    }
+}

common/src/commonMain/kotlin/com/artemchep/keyguard/feature/home/vault/screen/VaultViewStateProducer.kt

@@ -72,6 +72,7 @@ import com.artemchep.keyguard.common.service.placeholder.impl.CipherPlaceholder
 import com.artemchep.keyguard.common.service.placeholder.impl.CommentPlaceholder
 import com.artemchep.keyguard.common.service.placeholder.impl.CustomPlaceholder
 import com.artemchep.keyguard.common.service.placeholder.impl.DateTimePlaceholder
+import com.artemchep.keyguard.common.service.placeholder.impl.EnvironmentPlaceholder
 import com.artemchep.keyguard.common.service.placeholder.impl.TextTransformPlaceholder
 import com.artemchep.keyguard.common.service.placeholder.impl.UrlPlaceholder
 import com.artemchep.keyguard.common.service.placeholder.placeholderFormat
@@ -474,6 +475,7 @@ fun vaultViewScreenState(
                     CustomPlaceholder(secretOrNull),
                     DateTimePlaceholder(),
                     TextTransformPlaceholder(),
+                    EnvironmentPlaceholder(),
                 )
                 val extractors = LinkInfoRegistry(linkInfoExtractors)
                 val cipherUris = secretOrNull

wiki/PLACEHOLDERS.md

@@ -88,6 +88,16 @@ _Example_:
 https://example.com?user=joe&password=Password1%21
 ```
 
+#### Environmental variables
+
+System environment variables are supported. 
+The name of the variable must be enclosed in `%` characters.
+
+_Example_:
+```
+> {%HOME%}
+/home/username
+```
 
 #### Date-time
 ##### Local