Extract placeholder processing

src/main/kotlin/de/idetools/filename_template/CreateFileWithFilenameTemplateAction.kt

@@ -10,16 +10,15 @@ import com.intellij.openapi.project.Project
 import com.intellij.openapi.ui.InputValidatorEx
 import com.intellij.psi.PsiDirectory
 import com.intellij.psi.PsiElement
+import de.idetools.filename_template.placeholders.PlaceholderContext
+import de.idetools.filename_template.placeholders.PlaceholderProcessor
 import java.awt.event.InputEvent
-import java.time.LocalDateTime
-import java.time.ZoneOffset
 import java.util.function.Consumer
-import kotlin.math.max
 
 class CreateFileWithFilenameTemplateAction(
     text: String,
     description: String,
-    private val template: String
+    private val placeholderProcessor: PlaceholderProcessor
 ) :
     CreateFileAction(text, description, AllIcons.FileTypes.Unknown) {
 
@@ -32,7 +31,7 @@ class CreateFileWithFilenameTemplateAction(
         val contentPanel = NewItemSimplePopupPanel()
         val nameField = contentPanel.textField
 
-        nameField.text = processTemplate(template)
+        nameField.text = placeholderProcessor.processTemplate(PlaceholderContext(project, directory))
 
         val popup = NewItemPopupUtil.createNewItemPopup(IdeBundle.message("title.new.file"), contentPanel, nameField)
         contentPanel.setApplyAction { event: InputEvent? ->
@@ -51,49 +50,4 @@ class CreateFileWithFilenameTemplateAction(
         }
         popup.showCenteredInCurrentWindow(project)
     }
-
-    private fun processTemplate(template: String): String {
-        var placeholderLevel = 0
-        var placeholder = ""
-        var filename = ""
-
-        for (character in template) {
-            when (character) {
-                '{' -> {
-                    if (0 < placeholderLevel) {
-                        placeholder += character
-                    }
-
-                    placeholderLevel += 1
-                }
-                '}' -> {
-                    if (placeholderLevel == 1) {
-                        filename += processPlaceholder(placeholder)
-                        placeholder = ""
-                    }
-
-                    placeholderLevel = max(0, placeholderLevel - 1)
-
-                    if (0 < placeholderLevel) {
-                        placeholder += character
-                    }
-                }
-                else -> {
-                    if (0 < placeholderLevel) {
-                        placeholder += character
-                    } else {
-                        filename += character
-                    }
-                }
-            }
-        }
-
-        return filename
-    }
-
-    private fun processPlaceholder(placeholder: String): String =
-        when (placeholder) {
-            "EPOCH" -> LocalDateTime.now(ZoneOffset.UTC).toEpochSecond(ZoneOffset.UTC).toString()
-            else -> "{$placeholder}"
-        }
 }

src/main/kotlin/de/idetools/filename_template/InitializeFilenameTemplateActivity.kt

@@ -6,6 +6,9 @@ import com.intellij.openapi.actionSystem.Constraints
 import com.intellij.openapi.actionSystem.DefaultActionGroup
 import com.intellij.openapi.project.Project
 import com.intellij.openapi.startup.StartupActivity
+import de.idetools.filename_template.placeholders.DefaultPlaceholder
+import de.idetools.filename_template.placeholders.EpochPlaceholder
+import de.idetools.filename_template.placeholders.PlaceholderProcessor
 import de.idetools.filename_template.settings.FilenameTemplateSettingsState
 
 class InitializeFilenameTemplateActivity : StartupActivity {
@@ -16,6 +19,11 @@ class InitializeFilenameTemplateActivity : StartupActivity {
     internal fun initializeActions() {
         val settings: FilenameTemplateSettingsState = FilenameTemplateSettingsState.instance
 
+        val placeholders = listOf(
+            EpochPlaceholder(),
+            DefaultPlaceholder()
+        )
+
         val actionManager = ActionManager.getInstance()
         val newGroup = actionManager.getAction("NewGroup") as DefaultActionGroup
 
@@ -29,7 +37,7 @@ class InitializeFilenameTemplateActivity : StartupActivity {
             val action = CreateFileWithFilenameTemplateAction(
                 it.name,
                 it.description,
-                it.template
+                PlaceholderProcessor(it.template, placeholders)
             )
             val actionId = "FilenameTemplate.${it.name}"
             actionManager.registerAction(actionId, action)

src/main/kotlin/de/idetools/filename_template/placeholders/DefaultPlaceholder.kt

@@ -0,0 +1,8 @@
+package de.idetools.filename_template.placeholders
+
+class DefaultPlaceholder : Placeholder {
+    override fun supports(placeholder: String): Boolean = true
+
+    override fun process(placeholder: String, context: PlaceholderContext): String =
+        "{$placeholder}"
+}

src/main/kotlin/de/idetools/filename_template/placeholders/EpochPlaceholder.kt

@@ -0,0 +1,11 @@
+package de.idetools.filename_template.placeholders
+
+import java.time.LocalDateTime
+import java.time.ZoneOffset
+
+class EpochPlaceholder : Placeholder {
+    override fun supports(placeholder: String): Boolean = placeholder == "EPOCH"
+
+    override fun process(placeholder: String, context: PlaceholderContext): String =
+        LocalDateTime.now(ZoneOffset.UTC).toEpochSecond(ZoneOffset.UTC).toString()
+}

src/main/kotlin/de/idetools/filename_template/placeholders/Placeholder.kt

@@ -0,0 +1,6 @@
+package de.idetools.filename_template.placeholders
+
+interface Placeholder {
+    fun supports(placeholder: String): Boolean
+    fun process(placeholder: String, context: PlaceholderContext): String
+}

src/main/kotlin/de/idetools/filename_template/placeholders/PlaceholderContext.kt

@@ -0,0 +1,9 @@
+package de.idetools.filename_template.placeholders
+
+import com.intellij.openapi.project.Project
+import com.intellij.psi.PsiDirectory
+
+data class PlaceholderContext(
+    val project: Project,
+    val directory: PsiDirectory
+)

src/main/kotlin/de/idetools/filename_template/placeholders/PlaceholderProcessor.kt

@@ -0,0 +1,56 @@
+package de.idetools.filename_template.placeholders
+
+import java.util.function.Consumer
+import kotlin.math.max
+
+class PlaceholderProcessor(private val template: String, private val placeholders: List<Placeholder>) {
+
+    fun processTemplate(placeholderContext: PlaceholderContext): String {
+        var filename = ""
+        processTemplate(
+            template,
+            { filename += it },
+            { x ->
+                filename += placeholders
+                    .first { it.supports(x) }
+                    .process(x, placeholderContext)
+            })
+        return filename
+    }
+
+    private fun processTemplate(template: String, onCharacter: Consumer<Char>, onPlaceholder: Consumer<String>) {
+        var placeholderLevel = 0
+        var placeholder = ""
+
+        for (character in template) {
+            when (character) {
+                '{' -> {
+                    if (0 < placeholderLevel) {
+                        placeholder += character
+                    }
+
+                    placeholderLevel += 1
+                }
+                '}' -> {
+                    if (placeholderLevel == 1) {
+                        onPlaceholder.accept(placeholder)
+                        placeholder = ""
+                    }
+
+                    placeholderLevel = max(0, placeholderLevel - 1)
+
+                    if (0 < placeholderLevel) {
+                        placeholder += character
+                    }
+                }
+                else -> {
+                    if (0 < placeholderLevel) {
+                        placeholder += character
+                    } else {
+                        onCharacter.accept(character)
+                    }
+                }
+            }
+        }
+    }
+}