Refactor CronExpressionFormatter to improve maintainability (#192)

Extract logic from a single long method `cronToHumanReadable` into distinct parser helpers for shortcuts, day of month, days of week, and general time handling. Move repetitive static properties and small format helpers to the object scope.

app/src/main/java/com/m57/hermescontrol/util/CronExpressionFormatter.kt

@@ -3,55 +3,9 @@ package com.m57.hermescontrol.util
 import com.m57.hermescontrol.BuildConfig
 
 object CronExpressionFormatter {
-    fun cronToHumanReadable(schedule: String): String {
+    private val dowNames =
-        val clean = schedule.trim().replace("\\s+".toRegex(), " ")
-        val parts = clean.split(" ")
-        if (parts.size != 5) {
-            return schedule
-        }
-
-        try {
-            val minutePart = parts[0]
-            val hourPart = parts[1]
-            val domPart = parts[2]
-            val monthPart = parts[3]
-            val dowPart = parts[4]
-
-            // 1. Check for common simple shortcuts
-            // Every X minutes: */X * * * *
-            if (minutePart.startsWith("*/") &&
-                hourPart == "*" &&
-                domPart == "*" &&
-                monthPart == "*" &&
-                dowPart == "*"
-            ) {
-                val step = minutePart.substring(2).toIntOrNull()
-                if (step != null) return "Every $step minutes"
-            }
-
-            // Every X hours: 0 */X * * *
-            if (minutePart == "0" &&
-                hourPart.startsWith("*/") &&
-                domPart == "*" &&
-                monthPart == "*" &&
-                dowPart == "*"
-            ) {
-                val step = hourPart.substring(2).toIntOrNull()
-                if (step != null) return "Every $step hours"
-            }
-
-            // Midnight: 0 0 * * *
-            if (minutePart == "0" && hourPart == "0" && domPart == "*" && monthPart == "*" && dowPart == "*") {
-                return "Every day at midnight"
-            }
-
-            // At time every day: 0 H * * * or 0 H,H2 * * *
-            val hoursList = parseField(hourPart, 0, 23)
-            val minutesList = parseField(minutePart, 0, 59)
-
-            val dowNames =
         listOf("Sunday", "Monday", "Tuesday", "Wednesday", "Thursday", "Friday", "Saturday", "Sunday")
-            val monthNames =
+    private val monthNames =
         listOf(
             "",
             "January",
@@ -68,28 +22,67 @@ object CronExpressionFormatter {
             "December",
         )
 
-            // Format time: "09:00", "midnight", etc.
+    fun cronToHumanReadable(schedule: String): String {
-            fun formatTime(
+        val clean = schedule.trim().replace("\\s+".toRegex(), " ")
-                h: Int,
+        val parts = clean.split(" ")
-                m: Int,
+        if (parts.size != 5) {
-            ): String {
+            return schedule
-                if (h == 0 && m == 0) return "midnight"
-                return String.format("%02d:%02d", h, m)
         }
 
-            // Helper for ordinals: 1st, 2nd, 3rd, 4th...
+        try {
-            fun formatOrdinal(d: Int): String =
+            val minutePart = parts[0]
-                when {
+            val hourPart = parts[1]
-                    d % 100 in 11..13 -> "${d}th"
+            val domPart = parts[2]
-                    d % 10 == 1 -> "${d}st"
+            val monthPart = parts[3]
-                    d % 10 == 2 -> "${d}nd"
+            val dowPart = parts[4]
-                    d % 10 == 3 -> "${d}rd"
+
-                    else -> "${d}th"
+            parseSimpleShortcuts(minutePart, hourPart, domPart, monthPart, dowPart)?.let { return it }
+
+            val hoursList = parseField(hourPart, 0, 23)
+            val minutesList = parseField(minutePart, 0, 59)
+
+            parseDayOfMonthAndMonth(domPart, monthPart, dowPart, hoursList, minutesList)?.let { return it }
+            parseDaysOfWeek(dowPart, domPart, monthPart, hoursList, minutesList)?.let { return it }
+            parseGeneralTime(domPart, monthPart, dowPart, hoursList, minutesList)?.let { return it }
+
+            // Fallback
+            return schedule
+        } catch (e: Exception) {
+            if (BuildConfig.DEBUG) {
+                android.util.Log.w("CronExpressionFormatter", "Failed to parse cron: $schedule", e)
+            }
+            return "Raw: $schedule"
+        }
     }
 
-            // Day of Month / Month specific cases:
+    private fun parseSimpleShortcuts(
-            // "0 12 1 * *" -> "On the 1st of every month at 12:00"
+        minutePart: String,
-            // "0 0 1 1 *" -> "On January 1st at midnight"
+        hourPart: String,
+        domPart: String,
+        monthPart: String,
+        dowPart: String,
+    ): String? {
+        if (minutePart.startsWith("*/") && hourPart == "*" && domPart == "*" && monthPart == "*" && dowPart == "*") {
+            val step = minutePart.substring(2).toIntOrNull()
+            if (step != null) return "Every $step minutes"
+        }
+        if (minutePart == "0" && hourPart.startsWith("*/") && domPart == "*" && monthPart == "*" && dowPart == "*") {
+            val step = hourPart.substring(2).toIntOrNull()
+            if (step != null) return "Every $step hours"
+        }
+        if (minutePart == "0" && hourPart == "0" && domPart == "*" && monthPart == "*" && dowPart == "*") {
+            return "Every day at midnight"
+        }
+        return null
+    }
+
+    private fun parseDayOfMonthAndMonth(
+        domPart: String,
+        monthPart: String,
+        dowPart: String,
+        hoursList: List<Int>,
+        minutesList: List<Int>,
+    ): String? {
         if (domPart != "*" && monthPart != "*" && dowPart == "*") {
             val doms = parseField(domPart, 1, 31)
             val months = parseField(monthPart, 1, 12)
@@ -104,7 +97,6 @@ object CronExpressionFormatter {
                 }
             }
         }
-
         if (domPart != "*" && monthPart == "*" && dowPart == "*") {
             val doms = parseField(domPart, 1, 31)
             if (doms.size == 1 && hoursList.size == 1 && minutesList.size == 1) {
@@ -113,10 +105,16 @@ object CronExpressionFormatter {
                 return "On the $domStr of every month at $timeStr"
             }
         }
+        return null
+    }
 
-            // Days of week cases:
+    private fun parseDaysOfWeek(
-            // "30 8 * * 1-5" -> "At 08:30 Monday through Friday"
+        dowPart: String,
-            // "0 9 * * 1" -> "Every Monday at 09:00"
+        domPart: String,
+        monthPart: String,
+        hoursList: List<Int>,
+        minutesList: List<Int>,
+    ): String? {
         if (dowPart != "*" && domPart == "*" && monthPart == "*") {
             if (hoursList.size == 1 && minutesList.size == 1) {
                 val timeStr = formatTime(hoursList[0], minutesList[0])
@@ -139,9 +137,16 @@ object CronExpressionFormatter {
                 }
             }
         }
+        return null
+    }
 
-            // General case:
+    private fun parseGeneralTime(
-            // e.g. "0 9,21 * * *" -> "At 09:00 and 21:00 every day"
+        domPart: String,
+        monthPart: String,
+        dowPart: String,
+        hoursList: List<Int>,
+        minutesList: List<Int>,
+    ): String? {
         if (domPart == "*" && monthPart == "*" && dowPart == "*") {
             if (hoursList.isNotEmpty() && minutesList.size == 1) {
                 val timeStrings = hoursList.map { formatTime(it, minutesList[0]) }
@@ -154,15 +159,24 @@ object CronExpressionFormatter {
                 return "At $timeDesc every day"
             }
         }
+        return null
+    }
 
-            // Fallback
+    private fun formatTime(
-            return schedule
+        h: Int,
-        } catch (e: Exception) {
+        m: Int,
-            if (BuildConfig.DEBUG) {
+    ): String {
-                android.util.Log.w("CronExpressionFormatter", "Failed to parse cron: $schedule", e)
+        if (h == 0 && m == 0) return "midnight"
-            }
+        return String.format("%02d:%02d", h, m)
-            return "Raw: $schedule"
     }
+
+    private fun formatOrdinal(d: Int): String =
+        when {
+            d % 100 in 11..13 -> "${d}th"
+            d % 10 == 1 -> "${d}st"
+            d % 10 == 2 -> "${d}nd"
+            d % 10 == 3 -> "${d}rd"
+            else -> "${d}th"
         }
 
     private fun parseField(