Interceptor that allows override timeout settings per call.

TimeoutInterceptor.kt

const val CONNECT_TIMEOUT_MS = "CONNECT_TIMEOUT_MS"
const val READ_TIMEOUT_MS = "READ_TIMEOUT_MS"
const val WRITE_TIMEOUT_MS = "WRITE_TIMEOUT_MS"

/**
 * Allows dynamic setting of timeout headers.
 *
 * Usage:
 * ```
 * @Headers("$CONNECT_TIMEOUT:10000", "$READ_TIMEOUT:10000", "$WRITE_TIMEOUT:10000")
 * ```
 *
 * Read timeout = How long to wait for an API response (most commonly used timeout)
 * Write timeout = How long to wait for the app to send the request
 * Connect timeout = How long to wait to establish a connection with the API (TCP handshake)
 *
 * @see <a href="https://github.com/square/retrofit/issues/2561#issuecomment-345641958">Related GitHub Issue</a>
 */
object TimeoutInterceptor : Interceptor {
    override fun intercept(chain: Interceptor.Chain): Response {
        val request: Request = chain.request()

        val connectTimeout: Int = request.header(CONNECT_TIMEOUT_MS)
            ?.takeIf { it.isNotBlank() }?.toIntOrNull() ?: chain.connectTimeoutMillis()
        val readTimeout: Int = request.header(READ_TIMEOUT_MS)
            ?.takeIf { it.isNotBlank() }?.toIntOrNull() ?: chain.readTimeoutMillis()
        val writeTimeout: Int = request.header(WRITE_TIMEOUT_MS)
            ?.takeIf { it.isNotBlank() }?.toIntOrNull() ?: chain.writeTimeoutMillis()

        val builder: Request.Builder = request.newBuilder()
            .removeHeader(CONNECT_TIMEOUT_MS)
            .removeHeader(READ_TIMEOUT_MS)
            .removeHeader(WRITE_TIMEOUT_MS)

        return chain
            .withConnectTimeout(connectTimeout, TimeUnit.MILLISECONDS)
            .withReadTimeout(readTimeout, TimeUnit.MILLISECONDS)
            .withWriteTimeout(writeTimeout, TimeUnit.MILLISECONDS)
            .proceed(builder.build())
    }
}