/*
 * Copyright 2020 The Matrix.org Foundation C.I.C.
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.matrix.android.sdk.api.extensions

import java.util.regex.Pattern

const val emailPattern = "^[a-zA-Z0-9_!#\$%&'*+/=?`{|}~^-]+(?:\\.[a-zA-Z0-9_!#\$%&'*+/=?`{|}~^-]+)*@[a-zA-Z0-9-]+(?:\\.[a-zA-Z0-9-]+)*\$"
val emailAddress: Pattern = Pattern.compile(emailPattern)

fun CharSequence.ensurePrefix(prefix: CharSequence): CharSequence {
    return when {
        startsWith(prefix) -> this
        else -> "$prefix$this"
    }
}

/**
 * Check if a CharSequence is an email.
 */
fun CharSequence.isEmail() = emailAddress.matcher(this).matches()

/**
 * Append a new line and then the provided string.
 */
fun StringBuilder.appendNl(str: String) = append("\n").append(str)

/**
 * Returns null if the string is empty.
 */
fun String.ensureNotEmpty() = ifEmpty { null }
