add folding builder

Author: xepozz

src/main/kotlin/com/github/xepozz/crontab/ide/CronScheduleDescriber.kt

@@ -0,0 +1,69 @@
+package com.github.xepozz.crontab.ide
+
+object CronScheduleDescriber {
+    fun asHumanReadable(cron: String): String {
+        val fields = cron.trim().split("\\s+".toRegex())
+        if (fields.size != 5) {
+            throw IllegalArgumentException("Invalid cron expression. Expected 5 fields, got ${fields.size}")
+        }
+
+        val (minute, hour, dayOfMonth, month, dayOfWeek) = fields
+
+        return buildString {
+            append("Runs ")
+
+            // Minute
+            append(
+                when (minute) {
+                    "*" -> "every minute"
+                    else -> "at minute $minute"
+                }
+            )
+
+            // Hour
+            append(
+                when (hour) {
+                    "*" -> ""
+                    else -> " past hour $hour"
+                }
+            )
+
+            append(" ")
+
+            // Day of month
+            append(
+                when (dayOfMonth) {
+                    "*" -> "every day"
+                    else -> "on day $dayOfMonth of the month"
+                }
+            )
+
+            append(" ")
+
+            // Month
+            append(
+                when (month) {
+                    "*" -> "in every month"
+                    else -> "in $month"
+                }
+            )
+
+            append(" ")
+
+            // Day of week
+            append(
+                when (dayOfWeek) {
+                    "*" -> ""
+                    "0", "7" -> "on Sundays"
+                    "1" -> "on Mondays"
+                    "2" -> "on Tuesdays"
+                    "3" -> "on Wednesdays"
+                    "4" -> "on Thursdays"
+                    "5" -> "on Fridays"
+                    "6" -> "on Saturdays"
+                    else -> "on specific days ($dayOfWeek)"
+                }
+            )
+        }
+    }
+}

src/main/kotlin/com/github/xepozz/crontab/ide/CronScheduleFoldingBuilder.kt

@@ -0,0 +1,48 @@
+package com.github.xepozz.crontab.ide
+
+import com.github.xepozz.crontab.language.CrontabFile
+import com.github.xepozz.crontab.language.psi.CrontabSchedule
+import com.intellij.lang.ASTNode
+import com.intellij.lang.folding.CustomFoldingBuilder
+import com.intellij.lang.folding.FoldingDescriptor
+import com.intellij.openapi.editor.Document
+import com.intellij.openapi.editor.FoldingGroup
+import com.intellij.openapi.project.DumbService
+import com.intellij.openapi.util.TextRange
+import com.intellij.psi.PsiElement
+import com.intellij.psi.util.PsiTreeUtil
+
+class CronScheduleFoldingBuilder : CustomFoldingBuilder() {
+    override fun buildLanguageFoldRegions(
+        resultSet: MutableList<FoldingDescriptor>,
+        element: PsiElement,
+        document: Document,
+        p3: Boolean
+    ) {
+        val element = element as? CrontabFile ?: return
+        if (DumbService.isDumb(element.project)) return
+
+        PsiTreeUtil.findChildrenOfType(element, CrontabSchedule::class.java)
+            .map {
+                FoldingDescriptor(
+                    it.node,
+                    it.textRange,
+                    FoldingGroup.newGroup("Crontab Schedule Group"),
+                )
+            }
+            .forEach { resultSet.add(it) }
+
+    }
+
+    override fun getLanguagePlaceholderText(node: ASTNode, textRange: TextRange): String? {
+        val element = node.psi as? CrontabSchedule ?: return null
+
+        try {
+            return CronScheduleDescriber.asHumanReadable(element.text)
+        } catch (e: IllegalArgumentException) {
+        }
+        return null
+    }
+
+    override fun isRegionCollapsedByDefault(node: ASTNode): Boolean = true
+}

src/main/resources/META-INF/plugin.xml

@@ -27,5 +27,8 @@
                 implementationClass="com.github.xepozz.crontab.language.CrontabAnnotator"/>
         <multiHostInjector
                 implementation="com.github.xepozz.crontab.language.CrontabLanguageInjector"/>
+        <lang.foldingBuilder
+                language="Crontab"
+                implementationClass="com.github.xepozz.crontab.ide.CronScheduleFoldingBuilder"/>
     </extensions>
 </idea-plugin>