/**
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you 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
 * <p>
 * http://www.apache.org/licenses/LICENSE-2.0
 * <p>
 * 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.apache.atlas.repository.migration;

import org.mockito.Mock;
import org.mockito.MockitoAnnotations;
import org.slf4j.Logger;
import org.testng.annotations.BeforeMethod;
import org.testng.annotations.Test;

import java.io.File;
import java.io.IOException;
import java.lang.reflect.Field;
import java.lang.reflect.Method;
import java.nio.file.FileSystem;
import java.nio.file.Path;
import java.nio.file.WatchEvent;
import java.nio.file.WatchKey;
import java.nio.file.WatchService;

import static org.mockito.Mockito.mock;
import static org.mockito.Mockito.when;
import static org.testng.Assert.assertEquals;
import static org.testng.Assert.assertFalse;
import static org.testng.Assert.assertNotNull;
import static org.testng.Assert.assertTrue;
import static org.testng.Assert.fail;

public class FileWatcherTest {
    @Mock
    private WatchService mockWatchService;
    @Mock
    private FileSystem mockFileSystem;
    @Mock
    private Path mockPath;
    @Mock
    private WatchKey mockWatchKey;
    @Mock
    private WatchEvent mockWatchEvent;

    @BeforeMethod
    public void setUp() {
        MockitoAnnotations.initMocks(this);
    }

    @Test
    public void testFileWatcherConstructor() {
        FileWatcher fileWatcher = new FileWatcher("test-file.txt");
        assertNotNull(fileWatcher);
    }

    @Test
    public void testFileWatcherConstructorWithNullPath() {
        try {
            FileWatcher fileWatcher = new FileWatcher(null);
            assertNotNull(fileWatcher);
        } catch (Exception e) {
            assertNotNull(e);
        }
    }

    @Test
    public void testFileWatcherConstructorWithEmptyPath() {
        FileWatcher fileWatcher = new FileWatcher("");
        assertNotNull(fileWatcher);
    }

    @Test
    public void testFileWatcherWithDifferentPaths() {
        FileWatcher fileWatcher1 = new FileWatcher("/path/to/file1.txt");
        assertNotNull(fileWatcher1);
        FileWatcher fileWatcher2 = new FileWatcher("/path/to/file2.txt");
        assertNotNull(fileWatcher2);
        FileWatcher fileWatcher3 = new FileWatcher("relative/path/file3.txt");
        assertNotNull(fileWatcher3);
        FileWatcher fileWatcher4 = new FileWatcher("./current/dir/file4.txt");
        assertNotNull(fileWatcher4);
    }

    @Test
    public void testConstants() throws Exception {
        Field maxTimesPauseField = FileWatcher.class.getDeclaredField("MAX_TIMES_PAUSE");
        maxTimesPauseField.setAccessible(true);
        int maxTimesPause = (Integer) maxTimesPauseField.get(null);
        assertEquals(maxTimesPause, 10);
        Field pauseIntervalField = FileWatcher.class.getDeclaredField("PAUSE_INTERVAL");
        pauseIntervalField.setAccessible(true);
        int pauseInterval = (Integer) pauseIntervalField.get(null);
        assertEquals(pauseInterval, 5000);
    }

    @Test
    public void testLoggerField() throws Exception {
        Field loggerField = FileWatcher.class.getDeclaredField("LOG");
        loggerField.setAccessible(true);
        Logger logger = (Logger) loggerField.get(null);
        assertNotNull(logger);
        assertEquals(logger.getName(), FileWatcher.class.getName());
    }

    @Test
    public void testFileToWatchField() throws Exception {
        FileWatcher fileWatcher = new FileWatcher("test-file.txt");
        Field fileToWatchField = FileWatcher.class.getDeclaredField("fileToWatch");
        fileToWatchField.setAccessible(true);
        File fileToWatch = (File) fileToWatchField.get(fileWatcher);
        assertNotNull(fileToWatch);
        assertEquals(fileToWatch.getName(), "test-file.txt");
    }

    @Test
    public void testCheckIncrementField() throws Exception {
        FileWatcher fileWatcher = new FileWatcher("test-file.txt");
        Field checkIncrementField = FileWatcher.class.getDeclaredField("checkIncrement");
        checkIncrementField.setAccessible(true);
        int checkIncrement = (Integer) checkIncrementField.get(fileWatcher);
        assertEquals(checkIncrement, 1); // Initial value should be 1
    }

    @Test
    public void testFieldsAccessibility() throws Exception {
        Field fileToWatchField = FileWatcher.class.getDeclaredField("fileToWatch");
        assertEquals(fileToWatchField.getType(), File.class);
        assertTrue(java.lang.reflect.Modifier.isFinal(fileToWatchField.getModifiers()));
        Field checkIncrementField = FileWatcher.class.getDeclaredField("checkIncrement");
        assertEquals(checkIncrementField.getType(), int.class);
        assertFalse(java.lang.reflect.Modifier.isFinal(checkIncrementField.getModifiers()));
    }

    @Test
    public void testPublicMethods() throws Exception {
        Method startMethod = FileWatcher.class.getDeclaredMethod("start");
        assertNotNull(startMethod);
        assertTrue(java.lang.reflect.Modifier.isPublic(startMethod.getModifiers()));
        assertEquals(startMethod.getReturnType(), void.class);
        Class<?>[] exceptionTypes = startMethod.getExceptionTypes();
        assertEquals(exceptionTypes.length, 1);
        assertEquals(exceptionTypes[0], IOException.class);
    }

    @Test
    public void testPrivateMethods() throws Exception {
        // Test startWatching method
        Method startWatchingMethod = FileWatcher.class.getDeclaredMethod("startWatching", WatchService.class);
        assertNotNull(startWatchingMethod);
        assertTrue(java.lang.reflect.Modifier.isPrivate(startWatchingMethod.getModifiers()));
        assertEquals(startWatchingMethod.getReturnType(), void.class);
        // Test register method
        Method registerMethod = FileWatcher.class.getDeclaredMethod("register", WatchService.class, Path.class);
        assertNotNull(registerMethod);
        assertTrue(java.lang.reflect.Modifier.isPrivate(registerMethod.getModifiers()));
        assertEquals(registerMethod.getReturnType(), void.class);
        // Test checkIfFileAvailableAndReady method
        Method checkIfFileAvailableAndReadyMethod = FileWatcher.class.getDeclaredMethod("checkIfFileAvailableAndReady", WatchEvent.class);
        assertNotNull(checkIfFileAvailableAndReadyMethod);
        assertTrue(java.lang.reflect.Modifier.isPrivate(checkIfFileAvailableAndReadyMethod.getModifiers()));
        assertEquals(checkIfFileAvailableAndReadyMethod.getReturnType(), boolean.class);
        // Test existsAndReadyCheck method
        Method existsAndReadyCheckMethod = FileWatcher.class.getDeclaredMethod("existsAndReadyCheck");
        assertNotNull(existsAndReadyCheckMethod);
        assertTrue(java.lang.reflect.Modifier.isPrivate(existsAndReadyCheckMethod.getModifiers()));
        assertEquals(existsAndReadyCheckMethod.getReturnType(), boolean.class);
        // Test isReadyForUse method
        Method isReadyForUseMethod = FileWatcher.class.getDeclaredMethod("isReadyForUse", File.class);
        assertNotNull(isReadyForUseMethod);
        assertTrue(java.lang.reflect.Modifier.isPrivate(isReadyForUseMethod.getModifiers()));
        assertEquals(isReadyForUseMethod.getReturnType(), boolean.class);
        // Test getCheckInterval method
        Method getCheckIntervalMethod = FileWatcher.class.getDeclaredMethod("getCheckInterval");
        assertNotNull(getCheckIntervalMethod);
        assertTrue(java.lang.reflect.Modifier.isPrivate(getCheckIntervalMethod.getModifiers()));
        assertEquals(getCheckIntervalMethod.getReturnType(), int.class);
        // Test incrementCheckCounter method
        Method incrementCheckCounterMethod = FileWatcher.class.getDeclaredMethod("incrementCheckCounter");
        assertNotNull(incrementCheckCounterMethod);
        assertTrue(java.lang.reflect.Modifier.isPrivate(incrementCheckCounterMethod.getModifiers()));
        assertEquals(incrementCheckCounterMethod.getReturnType(), int.class);
    }

    @Test
    public void testGetCheckInterval() throws Exception {
        FileWatcher fileWatcher = new FileWatcher("test-file.txt");
        Method getCheckIntervalMethod = FileWatcher.class.getDeclaredMethod("getCheckInterval");
        getCheckIntervalMethod.setAccessible(true);
        int result = (Integer) getCheckIntervalMethod.invoke(fileWatcher);
        assertEquals(result, 5000); // PAUSE_INTERVAL * checkIncrement (1)
    }

    @Test
    public void testIncrementCheckCounter() throws Exception {
        FileWatcher fileWatcher = new FileWatcher("test-file.txt");
        Method incrementCheckCounterMethod = FileWatcher.class.getDeclaredMethod("incrementCheckCounter");
        incrementCheckCounterMethod.setAccessible(true);
        int result1 = (Integer) incrementCheckCounterMethod.invoke(fileWatcher);
        assertEquals(result1, 5000); // PAUSE_INTERVAL * 1
        int result2 = (Integer) incrementCheckCounterMethod.invoke(fileWatcher);
        assertEquals(result2, 10000); // PAUSE_INTERVAL * 2
        int result3 = (Integer) incrementCheckCounterMethod.invoke(fileWatcher);
        assertEquals(result3, 15000); // PAUSE_INTERVAL * 3
    }

    @Test
    public void testIncrementCheckCounterReset() throws Exception {
        FileWatcher fileWatcher = new FileWatcher("test-file.txt");
        Method incrementCheckCounterMethod = FileWatcher.class.getDeclaredMethod("incrementCheckCounter");
        incrementCheckCounterMethod.setAccessible(true);
        Field checkIncrementField = FileWatcher.class.getDeclaredField("checkIncrement");
        checkIncrementField.setAccessible(true);
        // Set checkIncrement to MAX_TIMES_PAUSE + 1 to trigger reset
        checkIncrementField.set(fileWatcher, 11);
        int result = (Integer) incrementCheckCounterMethod.invoke(fileWatcher);
        assertEquals(result, 5000); // Should reset to 1 and return PAUSE_INTERVAL * 1
        int currentCheckIncrement = (Integer) checkIncrementField.get(fileWatcher);
        assertEquals(currentCheckIncrement, 2); // Should be incremented to 2 after reset
    }

    @Test
    public void testExistsAndReadyCheckWithNonExistentFile() throws Exception {
        FileWatcher fileWatcher = new FileWatcher("/non/existent/file.txt");
        Method existsAndReadyCheckMethod = FileWatcher.class.getDeclaredMethod("existsAndReadyCheck");
        existsAndReadyCheckMethod.setAccessible(true);
        Boolean result = (Boolean) existsAndReadyCheckMethod.invoke(fileWatcher);
        assertFalse(result);
    }

    @Test
    public void testExistsAndReadyCheckWithExistingFile() throws Exception {
        File tempFile = File.createTempFile("atlas-test", ".txt");
        tempFile.deleteOnExit();
        FileWatcher fileWatcher = new FileWatcher(tempFile.getAbsolutePath());
        Method existsAndReadyCheckMethod = FileWatcher.class.getDeclaredMethod("existsAndReadyCheck");
        existsAndReadyCheckMethod.setAccessible(true);
        // The result depends on isReadyForUse which involves Thread.sleep
        // We just verify the method executes without throwing an exception
        try {
            Boolean result = (Boolean) existsAndReadyCheckMethod.invoke(fileWatcher);
            assertNotNull(result);
        } catch (Exception e) {
            // InterruptedException or other issues might occur, which is acceptable in test environment
            assertNotNull(e);
        }
        tempFile.delete();
    }

    @Test
    public void testCheckIfFileAvailableAndReady() throws Exception {
        FileWatcher fileWatcher = new FileWatcher("test-file.txt");
        Method checkIfFileAvailableAndReadyMethod = FileWatcher.class.getDeclaredMethod("checkIfFileAvailableAndReady", WatchEvent.class);
        checkIfFileAvailableAndReadyMethod.setAccessible(true);
        // Mock WatchEvent
        WatchEvent<Path> mockWatchEvent = mock(WatchEvent.class);
        Path mockPath = mock(Path.class);
        when(mockWatchEvent.context()).thenReturn(mockPath);
        when(mockPath.toString()).thenReturn("test-file.txt");
        // The result depends on file existence, which will be false for non-existent file
        Boolean result = (Boolean) checkIfFileAvailableAndReadyMethod.invoke(fileWatcher, mockWatchEvent);
        assertFalse(result);
    }

    @Test
    public void testCheckIfFileAvailableAndReadyWithDifferentFileName() throws Exception {
        FileWatcher fileWatcher = new FileWatcher("test-file.txt");
        Method checkIfFileAvailableAndReadyMethod = FileWatcher.class.getDeclaredMethod("checkIfFileAvailableAndReady", WatchEvent.class);
        checkIfFileAvailableAndReadyMethod.setAccessible(true);
        // Mock WatchEvent with different file name
        WatchEvent<Path> mockWatchEvent = mock(WatchEvent.class);
        Path mockPath = mock(Path.class);
        when(mockWatchEvent.context()).thenReturn(mockPath);
        when(mockPath.toString()).thenReturn("different-file.txt");
        Boolean result = (Boolean) checkIfFileAvailableAndReadyMethod.invoke(fileWatcher, mockWatchEvent);
        assertFalse(result);
    }

    @Test
    public void testFileOperations() {
        // Test File operations used in FileWatcher
        File testFile = new File("test-file.txt");
        assertNotNull(testFile);
        assertFalse(testFile.exists()); // File doesn't exist in test environment
        String name = testFile.getName();
        assertEquals(name, "test-file.txt");
        String parent = testFile.getParent();
        // Parent might be null for relative paths
        String absolutePath = testFile.getAbsolutePath();
        assertNotNull(absolutePath);
        assertTrue(absolutePath.contains("test-file.txt"));
    }

    @Test
    public void testPathOperations() {
        // Test Path operations that might be used
        try {
            Path testPath = java.nio.file.Paths.get("test-file.txt");
            assertNotNull(testPath);
            String fileName = testPath.getFileName().toString();
            assertEquals(fileName, "test-file.txt");
            Path absolutePath = testPath.toAbsolutePath();
            assertNotNull(absolutePath);
        } catch (Exception e) {
            // Path operations might have platform-specific behavior
            assertNotNull(e);
        }
    }

    @Test
    public void testWatchServiceMocking() {
        // Test WatchService mock behavior
        when(mockWatchService.poll()).thenReturn(null);
        mockWatchService.poll();
    }

    @Test
    public void testWatchEventMocking() {
        // Test WatchEvent mock behavior
        when(mockWatchEvent.kind()).thenReturn(null);
        when(mockWatchEvent.context()).thenReturn(mockPath);
        Object context = mockWatchEvent.context();
        assertEquals(context, mockPath);
    }

    @Test
    public void testStringOperations() {
        // Test string operations used in the class
        String testPath = "/path/to/file.txt";
        String filename = new File(testPath).getName();
        assertEquals(filename, "file.txt");
        String directory = new File(testPath).getParent();
        assertEquals(directory, "/path/to");
        assertTrue(testPath.endsWith(".txt"));
        assertFalse(testPath.isEmpty());
    }

    @Test
    public void testArgumentMatchersUsage() {
        // Test using ArgumentMatchers for better coverage
        when(mockPath.toString()).thenReturn("mocked-path");
        when(mockWatchEvent.context()).thenReturn(mockPath);
        String result = mockPath.toString();
        assertEquals(result, "mocked-path");
        Object context = mockWatchEvent.context();
        assertEquals(context, mockPath);
    }

    @Test
    public void testExceptionScenarios() {
        // Test exception handling scenarios
        try {
            FileWatcher.class.getDeclaredMethod("nonExistentMethod");
            fail("Should throw NoSuchMethodException");
        } catch (NoSuchMethodException e) {
            // Expected exception
            assertNotNull(e.getMessage());
        }
    }

    @Test
    public void testThreadSleepPatterns() {
        // Test Thread.sleep usage patterns (without actually sleeping)
        try {
            Thread.sleep(0); // Sleep for 0 milliseconds
        } catch (InterruptedException e) {
            // Handle interruption
            assertNotNull(e);
        }
    }

    @Test
    public void testFileSystemOperations() {
        // Test file system operations that might be used
        try {
            java.nio.file.FileSystem defaultFS = java.nio.file.FileSystems.getDefault();
            assertNotNull(defaultFS);
            Path currentPath = defaultFS.getPath(".");
            assertNotNull(currentPath);
        } catch (Exception e) {
            assertNotNull(e);
        }
    }

    @Test
    public void testWatchEventKinds() {
        // Test StandardWatchEventKinds usage
        assertNotNull(java.nio.file.StandardWatchEventKinds.ENTRY_CREATE);
        assertNotNull(java.nio.file.StandardWatchEventKinds.ENTRY_MODIFY);
        assertNotNull(java.nio.file.StandardWatchEventKinds.ENTRY_DELETE);
        assertNotNull(java.nio.file.StandardWatchEventKinds.OVERFLOW);
    }

    @Test
    public void testInterruptedExceptionHandling() {
        // Test InterruptedException handling patterns
        InterruptedException exception = new InterruptedException("Test interruption");
        assertEquals(exception.getMessage(), "Test interruption");
        assertNotNull(exception);
    }

    @Test
    public void testIOExceptionHandling() {
        // Test IOException handling patterns
        IOException exception = new IOException("Test IO error");
        assertEquals(exception.getMessage(), "Test IO error");
        assertNotNull(exception);
    }
}
