add terminal support class

cli/base/src/main/java/de/cotto/bitbook/cli/TerminalSupport.java

@@ -0,0 +1,44 @@
+package de.cotto.bitbook.cli;
+
+import org.apache.commons.lang3.StringUtils;
+import org.jline.reader.LineReader;
+import org.jline.terminal.Terminal;
+import org.springframework.stereotype.Component;
+
+import java.io.PrintWriter;
+import java.util.Optional;
+
+@Component
+public class TerminalSupport {
+    private final LineReader lineReader;
+    private final PromptChangeListener promptChangeListener;
+    private final PrintWriter writer;
+
+    public TerminalSupport(Terminal terminal, LineReader lineReader, PromptChangeListener promptChangeListener) {
+        this.lineReader = lineReader;
+        this.promptChangeListener = promptChangeListener;
+        writer = terminal.writer();
+    }
+
+    public void write(String text) {
+        writer.println(text);
+        writer.flush();
+    }
+
+    public Optional<String> request(String prompt) {
+        String answer = lineReader.readLine(prompt + " ");
+        if (StringUtils.isBlank(answer)) {
+            return Optional.empty();
+        } else {
+            return Optional.of(answer);
+        }
+    }
+
+    public void changePrompt(String newPrompt) {
+        promptChangeListener.changePrompt(newPrompt);
+    }
+
+    public void changePromptToDefault() {
+        promptChangeListener.changePromptToDefault();
+    }
+}

cli/base/src/test/java/de/cotto/bitbook/cli/TerminalSupportTest.java

@@ -0,0 +1,85 @@
+package de.cotto.bitbook.cli;
+
+import org.jline.reader.LineReader;
+import org.jline.terminal.Terminal;
+import org.junit.jupiter.api.BeforeEach;
+import org.junit.jupiter.api.Test;
+import org.junit.jupiter.api.extension.ExtendWith;
+import org.mockito.InOrder;
+import org.mockito.Mock;
+import org.mockito.Mockito;
+import org.mockito.junit.jupiter.MockitoExtension;
+
+import java.io.PrintWriter;
+
+import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.ArgumentMatchers.anyString;
+import static org.mockito.Mockito.verify;
+import static org.mockito.Mockito.when;
+
+@ExtendWith(MockitoExtension.class)
+class TerminalSupportTest {
+    private TerminalSupport terminalSupport;
+
+    @Mock
+    private Terminal terminal;
+
+    @Mock
+    private LineReader lineReader;
+
+    @Mock
+    private PromptChangeListener promptChangeListener;
+
+    @Mock
+    private PrintWriter writer;
+
+    @BeforeEach
+    void setUp() {
+        when(terminal.writer()).thenReturn(writer);
+        terminalSupport = new TerminalSupport(terminal, lineReader, promptChangeListener);
+    }
+
+    @Test
+    void write() {
+        terminalSupport.write("x");
+        InOrder inOrder = Mockito.inOrder(writer);
+        inOrder.verify(writer).println("x");
+        inOrder.verify(writer).flush();
+    }
+
+    @Test
+    void request_prompt() {
+        terminalSupport.request("?");
+        verify(lineReader).readLine("? ");
+    }
+
+    @Test
+    void request_empty() {
+        when(lineReader.readLine(anyString())).thenReturn("");
+        assertThat(terminalSupport.request("?")).isEmpty();
+    }
+
+    @Test
+    void request_blank() {
+        when(lineReader.readLine(anyString())).thenReturn("\t \r\n");
+        assertThat(terminalSupport.request("?")).isEmpty();
+    }
+
+    @Test
+    void request() {
+        when(lineReader.readLine(anyString())).thenReturn("hello");
+        assertThat(terminalSupport.request("?")).contains("hello");
+    }
+
+    @Test
+    void changePrompt() {
+        terminalSupport.changePrompt("x");
+        verify(promptChangeListener).changePrompt("x");
+    }
+
+    @Test
+    void changePromptToDefault() {
+        terminalSupport.changePromptToDefault();
+        verify(promptChangeListener).changePromptToDefault();
+    }
+}