auto detekt code from a number phone (#60)

ccp/build.gradle.kts

@@ -78,7 +78,7 @@ afterEvaluate {
                 groupId = "com.togisoft"
                 artifactId = "jetpack_country_code_picker"
                 // Update version in README when changing below
-                version = "2.2.7"
+                version = "2.2.8"
             }
         }
     }

ccp/src/main/java/com/togitech/ccp/component/TogiCountryCodePicker.kt

@@ -47,6 +47,7 @@ import com.togitech.ccp.data.CountryData
 import com.togitech.ccp.data.Iso31661alpha2
 import com.togitech.ccp.data.PhoneCode
 import com.togitech.ccp.data.utils.ValidatePhoneNumber
+import com.togitech.ccp.data.utils.extractCountryCode
 import com.togitech.ccp.data.utils.getCountryFromPhoneCode
 import com.togitech.ccp.data.utils.getUserIsoCode
 import com.togitech.ccp.data.utils.numberHint
@@ -62,6 +63,7 @@ private const val TAG = "TogiCountryCodePicker"
  * The first parameter is string pair of (country phone code, phone number) and the second parameter is
  * a boolean indicating whether the phone number is valid.
  * @param modifier Modifier to be applied to the inner OutlinedTextField.
+ * @param autoDetectCode Boolean indicating if will auto detect the code from initial phone number
  * @param enabled Boolean indicating whether the field is enabled.
  * @param shape Shape of the text field.
  * @param showCountryCode Whether to show the country code in the text field.
@@ -92,6 +94,7 @@ private const val TAG = "TogiCountryCodePicker"
 fun TogiCountryCodePicker(
     onValueChange: (Pair<PhoneCode, String>, Boolean) -> Unit,
     modifier: Modifier = Modifier,
+    autoDetectCode: Boolean = false,
     enabled: Boolean = true,
     shape: Shape = DEFAULT_TEXT_FIELD_SHAPE,
     showCountryCode: Boolean = true,
@@ -114,35 +117,44 @@ fun TogiCountryCodePicker(
 ) {
     val context = LocalContext.current
     val focusRequester = remember { FocusRequester() }
+
+    val countryCode = autoDetectedCountryCode(
+        autoDetectCode = autoDetectCode,
+        initialPhoneNumber = initialPhoneNumber,
+    )
+
+    val phoneNumberWithoutCode = if (countryCode != null) {
+        initialPhoneNumber?.replace(countryCode, "")
+    } else {
+        initialPhoneNumber
+    }
+
     var phoneNumber by remember {
         mutableStateOf(
             TextFieldValue(
-                text = initialPhoneNumber.orEmpty(),
-                selection = TextRange(initialPhoneNumber?.length ?: 0),
+                text = phoneNumberWithoutCode.orEmpty(),
+                selection = TextRange(phoneNumberWithoutCode?.length ?: 0),
             ),
         )
     }
     val keyboardController = LocalSoftwareKeyboardController.current
 
     var country: CountryData by rememberSaveable(
         context,
+        countryCode,
         initialCountryPhoneCode,
         initialCountryIsoCode,
     ) {
         mutableStateOf(
             configureInitialCountry(
-                initialCountryPhoneCode = initialCountryPhoneCode,
+                initialCountryPhoneCode = countryCode ?: initialCountryPhoneCode,
                 context = context,
                 initialCountryIsoCode = initialCountryIsoCode,
                 fallbackCountry = fallbackCountry,
             ),
         )
     }
 
-    if (initialPhoneNumber?.startsWith("+") == true) {
-        Log.e(TAG, "initialPhoneNumber must not include the country code")
-    }
-
     val phoneNumberTransformation = remember(country) {
         PhoneNumberTransformation(country.countryIso, context)
     }
@@ -310,6 +322,14 @@ private fun ClearIconButton(
     )
 }
 
+@Composable
+private fun autoDetectedCountryCode(autoDetectCode: Boolean, initialPhoneNumber: String?): String? =
+    if (initialPhoneNumber?.startsWith("+") == true && autoDetectCode) {
+        extractCountryCode(initialPhoneNumber)
+    } else {
+        null
+    }
+
 @Preview
 @Composable
 private fun TogiCountryCodePickerPreview() {

ccp/src/main/java/com/togitech/ccp/data/CountryData.kt

@@ -249,5 +249,6 @@ enum class CountryData(val countryIso: Iso31661alpha2, val countryPhoneCode: Pho
 
     companion object {
         val isoMap: Map<Iso31661alpha2, CountryData> = entries.associateBy { it.countryIso }
+        internal val phoneCodeMap: Map<PhoneCode, CountryData> = entries.associateBy { it.countryPhoneCode }
     }
 }

ccp/src/main/java/com/togitech/ccp/data/utils/CountryCodeUtils.kt

@@ -5,8 +5,10 @@ import android.telephony.TelephonyManager
 import com.togitech.ccp.data.CountryData
 import com.togitech.ccp.data.Iso31661alpha2
 import com.togitech.ccp.data.PhoneCode
+import kotlin.math.min
 
 private const val EMOJI_UNICODE = 0x1F1A5
+private const val MAX_LENGTH_COUNTRY_CODE = 3
 
 internal fun getCountryFromPhoneCode(code: PhoneCode, context: Context): CountryData? {
     val countries = CountryData.entries.filter { it.countryPhoneCode == code }
@@ -39,3 +41,15 @@ fun countryCodeToEmojiFlag(countryCode: Iso31661alpha2): String =
 
 private val Context.telephonyManager: TelephonyManager?
     get() = getSystemService(Context.TELEPHONY_SERVICE) as? TelephonyManager
+
+internal fun extractCountryCode(fullNumber: String): String? {
+    val numberLength = fullNumber.length
+    val minLength = min(a = numberLength, b = MAX_LENGTH_COUNTRY_CODE)
+    for (i in 1..minLength) {
+        val potentialCountryCode = fullNumber.substring(0, i)
+        if (CountryData.phoneCodeMap.containsKey(potentialCountryCode)) {
+            return potentialCountryCode
+        }
+    }
+    return null
+}