fix(common): correct date format in formatDate() for API compatibility

core/common/src/commonMain/kotlin/com/mifos/core/common/utils/ApiDateFormatter.kt

@@ -0,0 +1,189 @@
+/*
+ * Copyright 2025 Mifos Initiative
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See https://github.com/openMF/android-client/blob/master/LICENSE.md
+ */
+package com.mifos.core.common.utils
+
+import com.mifos.core.model.utils.DateConstants
+import kotlinx.datetime.Instant
+import kotlinx.datetime.LocalDate
+import kotlinx.datetime.TimeZone
+import kotlinx.datetime.toLocalDateTime
+
+/**
+ * Centralized date formatter for Fineract API requests.
+ *
+ * This object provides standardized date formatting methods to ensure
+ * consistency between the date strings sent to the API and the dateFormat
+ * parameter that specifies how they should be parsed.
+ *
+ * Usage:
+ * ```kotlin
+ * val payload = ClientPayload(
+ *     activationDate = ApiDateFormatter.formatForApi(dateMillis),
+ *     dateFormat = ApiDateFormatter.DATE_FORMAT,
+ *     locale = ApiDateFormatter.LOCALE
+ * )
+ * ```
+ */
+object ApiDateFormatter {
+
+    /**
+     * Standard date format for Fineract API: "dd MMMM yyyy"
+     * Example: "18 February 2026"
+     */
+    const val DATE_FORMAT = DateConstants.DATE_FORMAT
+
+    /**
+     * Standard locale for Fineract API
+     */
+    const val LOCALE = DateConstants.LOCALE
+
+    /**
+     * Format epoch milliseconds to API date string using standard format.
+     *
+     * @param millis Epoch milliseconds
+     * @return Date string in "dd MMMM yyyy" format (e.g., "18 February 2026")
+     */
+    fun formatForApi(millis: Long): String {
+        return formatForApi(millis, DateFormatPattern.FULL_MONTH)
+    }
+
+    /**
+     * Format epoch milliseconds to date string using specified pattern.
+     *
+     * @param millis Epoch milliseconds
+     * @param pattern The date format pattern to use
+     * @return Formatted date string
+     */
+    fun formatForApi(millis: Long, pattern: DateFormatPattern): String {
+        val dateTime = Instant
+            .fromEpochMilliseconds(millis)
+            .toLocalDateTime(TimeZone.currentSystemDefault())
+
+        return formatDateTime(dateTime, pattern)
+    }
+
+    /**
+     * Format LocalDate to API date string using standard format.
+     *
+     * @param date LocalDate to format
+     * @return Date string in "dd MMMM yyyy" format (e.g., "18 February 2026")
+     */
+    fun formatForApi(date: LocalDate): String {
+        return formatForApi(date, DateFormatPattern.FULL_MONTH)
+    }
+
+    /**
+     * Format LocalDate to date string using specified pattern.
+     *
+     * @param date LocalDate to format
+     * @param pattern The date format pattern to use
+     * @return Formatted date string
+     */
+    fun formatForApi(date: LocalDate, pattern: DateFormatPattern): String {
+        val day = date.dayOfMonth.toString().padStart(2, '0')
+        val month = date.month
+        val monthNumber = date.monthNumber.toString().padStart(2, '0')
+        val year = date.year
+
+        return when (pattern) {
+            DateFormatPattern.FULL_MONTH -> "$day ${month.toFullName()} $year"
+            DateFormatPattern.SHORT_MONTH -> "$day ${month.toShortName()} $year"
+            DateFormatPattern.NUMERIC_DASH -> "$day-$monthNumber-$year"
+            DateFormatPattern.NUMERIC_SLASH -> "$day/$monthNumber/$year"
+            DateFormatPattern.ISO -> "$year-$monthNumber-$day"
+            DateFormatPattern.FULL_MONTH_WITH_TIME -> "$day ${month.toFullName()} $year 00:00"
+        }
+    }
+
+    /**
+     * Format date components (day, month, year) to API date string.
+     *
+     * @param day Day of month (1-31)
+     * @param month Month number (1-12)
+     * @param year Year
+     * @return Date string in "dd MMMM yyyy" format
+     */
+    fun formatForApi(day: Int, month: Int, year: Int): String {
+        val dayStr = day.toString().padStart(2, '0')
+        val monthName = getMonthName(month)
+        return "$dayStr $monthName $year"
+    }
+
+    /**
+     * Format date from list of integers [year, month, day] to API date string.
+     *
+     * @param dateComponents List containing [year, month, day]
+     * @return Date string in "dd MMMM yyyy" format
+     */
+    fun formatFromList(dateComponents: List<Int>): String {
+        require(dateComponents.size >= 3) { "Date components list must have at least 3 elements" }
+        val year = dateComponents[0]
+        val month = dateComponents[1]
+        val day = dateComponents[2]
+        return formatForApi(day, month, year)
+    }
+
+    /**
+     * Get the date format pattern string for a given pattern enum.
+     *
+     * @param pattern The DateFormatPattern enum value
+     * @return The pattern string to send as dateFormat parameter
+     */
+    fun getDateFormatString(pattern: DateFormatPattern): String {
+        return pattern.pattern
+    }
+
+    private fun formatDateTime(
+        dateTime: kotlinx.datetime.LocalDateTime,
+        pattern: DateFormatPattern,
+    ): String {
+        val day = dateTime.dayOfMonth.toString().padStart(2, '0')
+        val month = dateTime.month
+        val monthNumber = dateTime.monthNumber.toString().padStart(2, '0')
+        val year = dateTime.year
+        val hour = dateTime.hour.toString().padStart(2, '0')
+        val minute = dateTime.minute.toString().padStart(2, '0')
+
+        return when (pattern) {
+            DateFormatPattern.FULL_MONTH -> "$day ${month.toFullName()} $year"
+            DateFormatPattern.SHORT_MONTH -> "$day ${month.toShortName()} $year"
+            DateFormatPattern.NUMERIC_DASH -> "$day-$monthNumber-$year"
+            DateFormatPattern.NUMERIC_SLASH -> "$day/$monthNumber/$year"
+            DateFormatPattern.ISO -> "$year-$monthNumber-$day"
+            DateFormatPattern.FULL_MONTH_WITH_TIME -> "$day ${month.toFullName()} $year $hour:$minute"
+        }
+    }
+
+    private fun kotlinx.datetime.Month.toFullName(): String {
+        return name.lowercase().replaceFirstChar { it.uppercase() }
+    }
+
+    private fun kotlinx.datetime.Month.toShortName(): String {
+        return name.take(3).lowercase().replaceFirstChar { it.uppercase() }
+    }
+
+    private fun getMonthName(month: Int): String {
+        return when (month) {
+            1 -> "January"
+            2 -> "February"
+            3 -> "March"
+            4 -> "April"
+            5 -> "May"
+            6 -> "June"
+            7 -> "July"
+            8 -> "August"
+            9 -> "September"
+            10 -> "October"
+            11 -> "November"
+            12 -> "December"
+            else -> throw IllegalArgumentException("Invalid month: $month")
+        }
+    }
+}

core/common/src/commonMain/kotlin/com/mifos/core/common/utils/DateFormatPattern.kt

@@ -0,0 +1,55 @@
+/*
+ * Copyright 2025 Mifos Initiative
+ *
+ * This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at https://mozilla.org/MPL/2.0/.
+ *
+ * See https://github.com/openMF/android-client/blob/master/LICENSE.md
+ */
+package com.mifos.core.common.utils
+
+/**
+ * Enum representing standard date format patterns used in Fineract API.
+ *
+ * The Fineract API accepts dates as strings with a dateFormat parameter
+ * that specifies how the date should be parsed. This enum provides
+ * standardized patterns to ensure consistency across the application.
+ */
+enum class DateFormatPattern(val pattern: String) {
+    /**
+     * Full month name format: "dd MMMM yyyy" (e.g., "18 February 2026")
+     * This is the standard format used by Fineract API for most date fields.
+     */
+    FULL_MONTH("dd MMMM yyyy"),
+
+    /**
+     * Abbreviated month name format: "dd MMM yyyy" (e.g., "18 Feb 2026")
+     * Used in some specific API endpoints.
+     */
+    SHORT_MONTH("dd MMM yyyy"),
+
+    /**
+     * Numeric format with dashes: "dd-MM-yyyy" (e.g., "18-02-2026")
+     * Commonly used for display purposes.
+     */
+    NUMERIC_DASH("dd-MM-yyyy"),
+
+    /**
+     * Numeric format with slashes: "dd/MM/yyyy" (e.g., "18/02/2026")
+     * Used for display purposes only, not recommended for API calls.
+     */
+    NUMERIC_SLASH("dd/MM/yyyy"),
+
+    /**
+     * ISO 8601 format: "yyyy-MM-dd" (e.g., "2026-02-18")
+     * Standard international date format.
+     */
+    ISO("yyyy-MM-dd"),
+
+    /**
+     * Full month with time: "dd MMMM yyyy HH:mm" (e.g., "18 February 2026 14:30")
+     * Used for timestamps with date and time.
+     */
+    FULL_MONTH_WITH_TIME("dd MMMM yyyy HH:mm"),
+}

core/common/src/commonMain/kotlin/com/mifos/core/common/utils/FormatDate.kt

@@ -9,20 +9,28 @@
  */
 package com.mifos.core.common.utils
 
-import kotlinx.datetime.TimeZone
-import kotlinx.datetime.number
-import kotlinx.datetime.toLocalDateTime
-import kotlin.time.ExperimentalTime
-import kotlin.time.Instant
-
-@OptIn(ExperimentalTime::class)
+/**
+ * Format epoch milliseconds to API-compatible date string.
+ *
+ * Returns date in "dd MMMM yyyy" format (e.g., "18 February 2026")
+ * which matches the standard Fineract API dateFormat parameter.
+ *
+ * @param millis Epoch milliseconds
+ * @return Formatted date string for API usage
+ * @see ApiDateFormatter for more formatting options
+ */
 fun formatDate(millis: Long): String {
-    val dateTime = Instant
-        .fromEpochMilliseconds(millis)
-        .toLocalDateTime(TimeZone.currentSystemDefault())
+    return ApiDateFormatter.formatForApi(millis)
+}
 
-    val day = dateTime.day.toString().padStart(2, '0')
-    val month = dateTime.month.number.toString().padStart(2, '0')
-    val year = dateTime.year
-    return "$day/$month/$year"
+/**
+ * Format epoch milliseconds to date string using specified pattern.
+ *
+ * @param millis Epoch milliseconds
+ * @param pattern The date format pattern to use
+ * @return Formatted date string
+ * @see ApiDateFormatter for more formatting options
+ */
+fun formatDate(millis: Long, pattern: DateFormatPattern): String {
+    return ApiDateFormatter.formatForApi(millis, pattern)
 }

core/database/src/commonMain/kotlin/com/mifos/room/entities/collectionsheet/CollectionSheetPayload.kt

@@ -9,6 +9,7 @@
  */
 package com.mifos.room.entities.collectionsheet
 
+import com.mifos.core.common.utils.ApiDateFormatter
 import com.mifos.core.model.objects.collectionsheets.BulkSavingsDueTransaction
 import com.mifos.core.model.utils.IgnoredOnParcel
 import com.mifos.core.model.utils.Parcelable
@@ -34,9 +35,9 @@ data class CollectionSheetPayload(
 
     var clientsAttendance: MutableList<ClientsAttendance> = ArrayList(),
 
-    var dateFormat: String = "dd MMMM yyyy",
+    var dateFormat: String = ApiDateFormatter.DATE_FORMAT,
 
-    var locale: String = "en",
+    var locale: String = ApiDateFormatter.LOCALE,
 
     var transactionDate: String? = null,
 

core/database/src/commonMain/kotlin/com/mifos/room/entities/collectionsheet/ProductiveCollectionSheetPayload.kt

@@ -9,6 +9,7 @@
  */
 package com.mifos.room.entities.collectionsheet
 
+import com.mifos.core.common.utils.ApiDateFormatter
 import com.mifos.core.model.utils.Parcelable
 import com.mifos.core.model.utils.Parcelize
 import com.mifos.room.entities.noncore.BulkRepaymentTransactions
@@ -24,9 +25,9 @@ data class ProductiveCollectionSheetPayload(
 
     var calendarId: Int? = 0,
 
-    var dateFormat: String? = "dd MMMM yyyy",
+    var dateFormat: String? = ApiDateFormatter.DATE_FORMAT,
 
-    var locale: String? = "en",
+    var locale: String? = ApiDateFormatter.LOCALE,
 
     var transactionDate: String? = null,
 ) : Parcelable

core/model/src/commonMain/kotlin/com/mifos/core/model/objects/account/loan/LoanApproval.kt

@@ -9,6 +9,7 @@
  */
 package com.mifos.core.model.objects.account.loan
 
+import com.mifos.core.model.utils.DateConstants
 import com.mifos.core.model.utils.Parcelable
 import com.mifos.core.model.utils.Parcelize
 
@@ -22,7 +23,7 @@ class LoanApproval(
 
     var note: String? = null,
 
-    var locale: String = "en",
+    var locale: String = DateConstants.LOCALE,
 
-    var dateFormat: String = "dd MMMM yyyy",
+    var dateFormat: String = DateConstants.DATE_FORMAT,
 ) : Parcelable

core/model/src/commonMain/kotlin/com/mifos/core/model/objects/account/loan/LoanApprovalRequest.kt

@@ -9,6 +9,7 @@
  */
 package com.mifos.core.model.objects.account.loan
 
+import com.mifos.core.model.utils.DateConstants
 import com.mifos.core.model.utils.Parcelable
 import com.mifos.core.model.utils.Parcelize
 
@@ -17,9 +18,9 @@ import com.mifos.core.model.utils.Parcelize
  */
 @Parcelize
 data class LoanApprovalRequest(
-    var locale: String = "en",
+    var locale: String = DateConstants.LOCALE,
 
-    var dateFormat: String = "dd MM yyyy",
+    var dateFormat: String = DateConstants.DATE_FORMAT,
 
     var approvedOnDate: String? = null,
 

core/model/src/commonMain/kotlin/com/mifos/core/model/objects/account/loan/LoanDisbursement.kt

@@ -9,6 +9,7 @@
  */
 package com.mifos.core.model.objects.account.loan
 
+import com.mifos.core.model.utils.DateConstants
 import com.mifos.core.model.utils.Parcelable
 import com.mifos.core.model.utils.Parcelize
 
@@ -22,7 +23,7 @@ data class LoanDisbursement(
 
     var paymentId: Int? = null,
 
-    var locale: String? = "en",
+    var locale: String? = DateConstants.LOCALE,
 
-    var dateFormat: String? = "dd MMMM yyyy",
+    var dateFormat: String? = DateConstants.DATE_FORMAT,
 ) : Parcelable