package ch.fhnw.thga.gradleplugins;

import static ch.fhnw.thga.gradleplugins.FregeExtension.DEFAULT_DOWNLOAD_DIRECTORY;
import static ch.fhnw.thga.gradleplugins.FregePlugin.COMPILE_FREGE_TASK_NAME;
import static ch.fhnw.thga.gradleplugins.FregePlugin.FREGE_EXTENSION_NAME;
import static ch.fhnw.thga.gradleplugins.FregePlugin.FREGE_PLUGIN_ID;
import static ch.fhnw.thga.gradleplugins.FregePlugin.DEPS_FREGE_TASK_NAME;
import static ch.fhnw.thga.gradleplugins.FregePlugin.RUN_FREGE_TASK_NAME;
import static ch.fhnw.thga.gradleplugins.FregePlugin.SETUP_FREGE_TASK_NAME;
import static ch.fhnw.thga.gradleplugins.FregePlugin.REPL_FREGE_TASK_NAME;
import static ch.fhnw.thga.gradleplugins.GradleBuildFileConversionTest.createPluginsSection;
import static org.gradle.testkit.runner.TaskOutcome.FAILED;
import static org.gradle.testkit.runner.TaskOutcome.FROM_CACHE;
import static org.gradle.testkit.runner.TaskOutcome.SUCCESS;
import static org.gradle.testkit.runner.TaskOutcome.UP_TO_DATE;
import static org.junit.jupiter.api.Assertions.assertEquals;
import static org.junit.jupiter.api.Assertions.assertTrue;

import java.io.BufferedWriter;
import java.io.File;
import java.io.FileWriter;
import java.io.IOException;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.stream.Stream;

import org.gradle.api.Project;
import org.gradle.testfixtures.ProjectBuilder;
import org.gradle.testkit.runner.BuildResult;
import org.gradle.testkit.runner.GradleRunner;
import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.BeforeEach;
import org.junit.jupiter.api.DisplayNameGenerator;
import org.junit.jupiter.api.IndicativeSentencesGeneration;
import org.junit.jupiter.api.Nested;
import org.junit.jupiter.api.Test;
import org.junit.jupiter.api.TestInstance;
import org.junit.jupiter.api.TestInstance.Lifecycle;
import org.junit.jupiter.api.io.TempDir;

import ch.fhnw.thga.gradleplugins.internal.DependencyFregeTask;

@TestInstance(Lifecycle.PER_CLASS)
public class FregePluginFunctionalTest {
        private static final String NEW_LINE = System.lineSeparator();
        private static final String SIMPLE_FREGE_CODE = String.join(NEW_LINE, "module ch.fhnw.thga.Completion where",
                        NEW_LINE, NEW_LINE, "  complete :: Int -> (Int, String)", NEW_LINE,
                        "  complete i = (i, \"Frege rocks\")",
                        NEW_LINE);

        private static FregeDTOBuilder fregeBuilder;

        @TempDir
        File testProjectDir;
        private File buildFile;
        private File settingsFile;
        private Project project;

        private void writeFile(File destination, String content, boolean append) throws IOException {
                try (BufferedWriter output = new BufferedWriter(new FileWriter(destination, append))) {
                        output.write(content);
                }
        }

        private void writeToFile(File destination, String content) throws IOException {
                writeFile(destination, content, false);
        }

        private void appendToFile(File destination, String content) throws IOException {
                writeFile(destination, "\n" + content, true);
        }

        private static String createFregeSection(FregeDTO fregeDTO) {
                return String.format("%s {\n  %s\n}", FREGE_EXTENSION_NAME, fregeDTO.toBuildFile());
        }

        private BuildResult runGradleTask(String... taskName) {
                return GradleRunner.create().withProjectDir(testProjectDir).withPluginClasspath()
                                .withArguments(taskName)
                                .build();
        }

        private BuildResult runAndFailGradleTask(String taskName, String... args) {
                return GradleRunner.create().withProjectDir(testProjectDir).withPluginClasspath()
                                .withArguments(taskName)
                                .buildAndFail();
        }

        private void setupDefaultFregeProjectStructure(String fregeCode, String fregeFileName, String buildFileConfig)
                        throws Exception {
                Files.createDirectories(testProjectDir.toPath().resolve(Paths.get("src", "main", "frege")));
                File fregeFile = testProjectDir.toPath().resolve(Paths.get("src", "main", "frege", fregeFileName))
                                .toFile();
                writeToFile(fregeFile, fregeCode);
                appendToFile(buildFile, buildFileConfig);
        }

        @BeforeAll
        void beforeAll() throws Exception {
                settingsFile = new File(testProjectDir, "settings.gradle");
                writeToFile(settingsFile, "rootProject.name='frege-plugin'");
                project = ProjectBuilder.builder().withProjectDir(testProjectDir).build();
                project.getPluginManager().apply(FREGE_PLUGIN_ID);

        }

        @BeforeEach
        void setup() throws Exception {
                buildFile = new File(testProjectDir, "build.gradle");
                writeToFile(buildFile, createPluginsSection(Stream.of(FREGE_PLUGIN_ID)));
                fregeBuilder = FregeDTOBuilder.getInstance();
        }

        @AfterEach
        void cleanup() {
                testProjectDir.delete();
        }

        @Nested
        @TestInstance(Lifecycle.PER_CLASS)
        @IndicativeSentencesGeneration(separator = " -> ", generator = DisplayNameGenerator.ReplaceUnderscores.class)
        class Setup_frege_task_works {

                @Test
                void given_minimal_build_file_config() throws Exception {
                        String minimalBuildFileConfig = createFregeSection(
                                        fregeBuilder.version("'3.25.84'").release("'3.25alpha'").build());
                        appendToFile(buildFile, minimalBuildFileConfig);

                        BuildResult result = runGradleTask(SETUP_FREGE_TASK_NAME);

                        assertTrue(project.getTasks().getByName(SETUP_FREGE_TASK_NAME) instanceof SetupFregeTask);
                        assertEquals(SUCCESS, result.task(":" + SETUP_FREGE_TASK_NAME).getOutcome());
                        assertTrue(testProjectDir.toPath()
                                        .resolve(Paths.get(DEFAULT_DOWNLOAD_DIRECTORY, "frege3.25.84.jar"))
                                        .toFile().exists());
                }

                @Test
                void given_custom_frege_compiler_download_directory_in_build_file_config() throws Exception {
                        String buildFileConfigWithCustomDownloadDir = createFregeSection(fregeBuilder
                                        .version("'3.25.84'")
                                        .release("'3.25alpha'")
                                        .compilerDownloadDir("layout.projectDirectory.dir('dist')").build());
                        appendToFile(buildFile, buildFileConfigWithCustomDownloadDir);

                        BuildResult result = runGradleTask(SETUP_FREGE_TASK_NAME);

                        assertTrue(project.getTasks().getByName(SETUP_FREGE_TASK_NAME) instanceof SetupFregeTask);
                        assertEquals(SUCCESS, result.task(":" + SETUP_FREGE_TASK_NAME).getOutcome());
                        assertTrue(testProjectDir.toPath().resolve(Paths.get("dist", "frege3.25.84.jar")).toFile()
                                        .exists());
                }
        }

        @Nested
        @TestInstance(Lifecycle.PER_CLASS)
        @IndicativeSentencesGeneration(separator = " -> ", generator = DisplayNameGenerator.ReplaceUnderscores.class)
        class Compile_frege_task_works {

                @Test
                void given_frege_code_in_default_source_dir_and_minimal_build_file_config() throws Exception {
                        String completionFr = "Completion.fr";
                        String minimalBuildFileConfig = createFregeSection(
                                        fregeBuilder.version("'3.25.84'").release("'3.25alpha'").build());
                        setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr, minimalBuildFileConfig);

                        BuildResult result = runGradleTask(COMPILE_FREGE_TASK_NAME);

                        assertTrue(project.getTasks().getByName(COMPILE_FREGE_TASK_NAME) instanceof CompileFregeTask);
                        assertEquals(SUCCESS, result.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());
                        assertTrue(new File(
                                        testProjectDir.getAbsolutePath()
                                                        + "/build/classes/main/frege/ch/fhnw/thga/Completion.java")
                                                                        .exists());
                        assertTrue(new File(
                                        testProjectDir.getAbsolutePath()
                                                        + "/build/classes/main/frege/ch/fhnw/thga/Completion.class")
                                                                        .exists());
                }

                @Test
                void given_frege_code_and_many_compiler_flags() throws Exception {
                        String completionFr = "Completion.fr";
                        String buildConfigWithCompilerFlags = createFregeSection(fregeBuilder.version("'3.25.84'")
                                        .release("'3.25alpha'").compilerFlags("['-v', '-make', '-O', '-hints']")
                                        .build());
                        setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr,
                                        buildConfigWithCompilerFlags);

                        BuildResult result = runGradleTask(COMPILE_FREGE_TASK_NAME);

                        assertTrue(project.getTasks().getByName(COMPILE_FREGE_TASK_NAME) instanceof CompileFregeTask);
                        assertEquals(SUCCESS, result.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());
                        assertTrue(new File(
                                        testProjectDir.getAbsolutePath()
                                                        + "/build/classes/main/frege/ch/fhnw/thga/Completion.java")
                                                                        .exists());
                        assertTrue(new File(
                                        testProjectDir.getAbsolutePath()
                                                        + "/build/classes/main/frege/ch/fhnw/thga/Completion.class")
                                                                        .exists());
                }

                @Test
                void given_frege_code_in_custom_source_dir_and_custom_output_dir_and_minimal_build_file_config()
                                throws Exception {
                        Path customMainSourceDir = testProjectDir.toPath().resolve(Paths.get("src", "frege"));
                        Files.createDirectories(customMainSourceDir);
                        File completionFr = customMainSourceDir.resolve("Completion.fr").toFile();
                        writeToFile(completionFr, SIMPLE_FREGE_CODE);
                        String minimalBuildFileConfig = createFregeSection(
                                        fregeBuilder.version("'3.25.84'").release("'3.25alpha'")
                                                        .mainSourceDir("layout.projectDirectory.dir('src/frege')")
                                                        .outputDir("layout.buildDirectory.dir('frege')").build());
                        appendToFile(buildFile, minimalBuildFileConfig);

                        BuildResult result = runGradleTask(COMPILE_FREGE_TASK_NAME);

                        assertTrue(project.getTasks().getByName(COMPILE_FREGE_TASK_NAME) instanceof CompileFregeTask);
                        assertEquals(SUCCESS, result.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());
                        assertTrue(
                                        new File(testProjectDir.getAbsolutePath()
                                                        + "/build/frege/ch/fhnw/thga/Completion.java").exists());
                        assertTrue(
                                        new File(testProjectDir.getAbsolutePath()
                                                        + "/build/frege/ch/fhnw/thga/Completion.class").exists());
                }

                @Test
                void and_is_up_to_date_given_no_code_changes() throws Exception {
                        String completionFr = "Completion.fr";
                        String minimalBuildFileConfig = createFregeSection(
                                        fregeBuilder.version("'3.25.84'").release("'3.25alpha'").build());
                        setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr, minimalBuildFileConfig);

                        BuildResult first = runGradleTask(COMPILE_FREGE_TASK_NAME);
                        assertEquals(SUCCESS, first.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());

                        BuildResult second = runGradleTask(COMPILE_FREGE_TASK_NAME);
                        assertEquals(UP_TO_DATE, second.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());
                }

                @Test
                void and_is_cached_given_cache_hit() throws Exception {
                        String completionFr = "Completion.fr";
                        String minimalBuildFileConfig = createFregeSection(
                                        fregeBuilder.version("'3.25.84'").release("'3.25alpha'").build());
                        setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr, minimalBuildFileConfig);

                        BuildResult first = runGradleTask(COMPILE_FREGE_TASK_NAME, "--build-cache");
                        assertEquals(SUCCESS, first.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());

                        String codeChange = String.join(NEW_LINE, "module ch.fhnw.thga.Completion where", NEW_LINE,
                                        NEW_LINE,
                                        "  frob :: Int -> (Int, String)", NEW_LINE, "  frob i = (i, \"Frege rocks\")",
                                        NEW_LINE);
                        setupDefaultFregeProjectStructure(codeChange, completionFr, "");

                        BuildResult second = runGradleTask(COMPILE_FREGE_TASK_NAME, "--build-cache");
                        assertEquals(SUCCESS, second.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());

                        setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr, "");
                        BuildResult third = runGradleTask(COMPILE_FREGE_TASK_NAME, "--build-cache");
                        assertEquals(FROM_CACHE, third.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());
                }

                @Test
                void given_two_dependent_frege_files_in_default_source_dir_and_minimal_build_file_config()
                                throws Exception {
                        String completionFr = "Completion.fr";
                        String frobFr = "Frob.fr";
                        String frobCode = String.join(NEW_LINE, "module ch.fhnw.thga.Frob where", NEW_LINE, NEW_LINE,
                                        "import ch.fhnw.thga.Completion (complete)", NEW_LINE,
                                        "frob i = complete $ i + i", NEW_LINE);

                        String minimalBuildFileConfig = createFregeSection(
                                        fregeBuilder.version("'3.25.84'").release("'3.25alpha'").build());
                        setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr, minimalBuildFileConfig);
                        setupDefaultFregeProjectStructure(frobCode, frobFr, "");

                        BuildResult result = runGradleTask(COMPILE_FREGE_TASK_NAME);

                        assertTrue(project.getTasks().getByName(COMPILE_FREGE_TASK_NAME) instanceof CompileFregeTask);
                        assertEquals(SUCCESS, result.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());
                        assertTrue(new File(
                                        testProjectDir.getAbsolutePath()
                                                        + "/build/classes/main/frege/ch/fhnw/thga/Completion.java")
                                                                        .exists());
                        assertTrue(new File(
                                        testProjectDir.getAbsolutePath()
                                                        + "/build/classes/main/frege/ch/fhnw/thga/Completion.class")
                                                                        .exists());
                        assertTrue(new File(testProjectDir.getAbsolutePath()
                                        + "/build/classes/main/frege/ch/fhnw/thga/Frob.java")
                                                        .exists());
                        assertTrue(new File(testProjectDir.getAbsolutePath()
                                        + "/build/classes/main/frege/ch/fhnw/thga/Frob.class")
                                                        .exists());
                }
        }

        @Nested
        @TestInstance(Lifecycle.PER_CLASS)
        @IndicativeSentencesGeneration(separator = " -> ", generator = DisplayNameGenerator.ReplaceUnderscores.class)
        class Compile_frege_task_fails {
                @Test
                void given_frege_code_and_illegal_compiler_flags() throws Exception {
                        String completionFr = "Completion.fr";
                        String buildConfigWithIllegalCompilerFlags = createFregeSection(fregeBuilder
                                        .version("'3.25.84'")
                                        .release("'3.25alpha'").compilerFlags("['-make', '-bla']").build());
                        setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr,
                                        buildConfigWithIllegalCompilerFlags);

                        BuildResult result = runAndFailGradleTask(COMPILE_FREGE_TASK_NAME);

                        assertTrue(project.getTasks().getByName(COMPILE_FREGE_TASK_NAME) instanceof CompileFregeTask);
                        assertEquals(FAILED, result.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());
                }

                @Test
                void given_two_dependent_frege_files_in_default_source_dir_and_without_make_compiler_flag()
                                throws Exception {
                        String completionFr = "Completion.fr";
                        String frobFr = "Frob.fr";
                        String frobCode = String.join(NEW_LINE, "module ch.fhnw.thga.Frob where", NEW_LINE, NEW_LINE,
                                        "import ch.fhnw.thga.Completion (complete)", NEW_LINE,
                                        "frob i = complete $ i + i", NEW_LINE);

                        String minimalBuildFileConfigWithoutMake = createFregeSection(
                                        fregeBuilder.version("'3.25.84'").release("'3.25alpha'").compilerFlags("['-v']")
                                                        .build());
                        setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr,
                                        minimalBuildFileConfigWithoutMake);
                        setupDefaultFregeProjectStructure(frobCode, frobFr, "");

                        BuildResult result = runAndFailGradleTask(COMPILE_FREGE_TASK_NAME);

                        assertTrue(project.getTasks().getByName(COMPILE_FREGE_TASK_NAME) instanceof CompileFregeTask);
                        assertEquals(FAILED, result.task(":" + COMPILE_FREGE_TASK_NAME).getOutcome());
                }
        }

        @Nested
        @TestInstance(Lifecycle.PER_CLASS)
        @IndicativeSentencesGeneration(separator = " -> ", generator = DisplayNameGenerator.ReplaceUnderscores.class)
        class Run_frege_task_works {
                @Test
                void given_frege_file_with_main_function_and_main_module_config() throws Exception {
                        String fregeCode = String.join(NEW_LINE, "module ch.fhnw.thga.Main where", NEW_LINE, NEW_LINE,
                                        "  main = do", NEW_LINE, "    println \"Frege rocks\"", NEW_LINE);
                        String mainFr = "Main.fr";
                        String buildFileConfig = createFregeSection(
                                        fregeBuilder.version("'3.25.84'").release("'3.25alpha'")
                                                        .mainModule("'ch.fhnw.thga.Main'").build());
                        setupDefaultFregeProjectStructure(fregeCode, mainFr, buildFileConfig);

                        BuildResult result = runGradleTask(RUN_FREGE_TASK_NAME);
                        assertTrue(project.getTasks().getByName(RUN_FREGE_TASK_NAME) instanceof RunFregeTask);
                        assertEquals(SUCCESS, result.task(":" + RUN_FREGE_TASK_NAME).getOutcome());
                        assertTrue(result.getOutput().contains("Frege rocks"));
                }

                @Test
                void given_frege_file_without_main_function() throws Exception {
                        String completionFr = "Completion.fr";
                        String buildFileConfig = createFregeSection(
                                        fregeBuilder.version("'3.25.84'").release("'3.25alpha'")
                                                        .mainModule("'ch.fhnw.thga.Completion'").build());
                        setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr, buildFileConfig);

                        BuildResult result = runAndFailGradleTask(RUN_FREGE_TASK_NAME);
                        assertTrue(project.getTasks().getByName(RUN_FREGE_TASK_NAME) instanceof RunFregeTask);
                        assertEquals(FAILED, result.task(":" + RUN_FREGE_TASK_NAME).getOutcome());
                        assertTrue(result.getOutput().contains("Main method not found"));
                }

                @Test
                void given_frege_file_with_main_function_and_main_module_command_line_option() throws Exception {
                        String fregeCode = String.join(NEW_LINE, "module ch.fhnw.thga.Main where", NEW_LINE, NEW_LINE,
                                        "  main = do", NEW_LINE, "    println \"Frege rocks\"", NEW_LINE);
                        String mainFr = "Main.fr";
                        String buildFileConfig = createFregeSection(
                                        fregeBuilder.version("'3.25.84'").release("'3.25alpha'").build());
                        setupDefaultFregeProjectStructure(fregeCode, mainFr, buildFileConfig);

                        BuildResult result = runGradleTask(RUN_FREGE_TASK_NAME, "--mainModule=ch.fhnw.thga.Main");
                        assertTrue(project.getTasks().getByName(RUN_FREGE_TASK_NAME) instanceof RunFregeTask);
                        assertEquals(SUCCESS, result.task(":" + RUN_FREGE_TASK_NAME).getOutcome());
                        assertTrue(result.getOutput().contains("Frege rocks"));
                }
        }

        @Nested
        @TestInstance(Lifecycle.PER_CLASS)
        @IndicativeSentencesGeneration(separator = " -> ", generator = DisplayNameGenerator.ReplaceUnderscores.class)
        class Deps_frege_task_works {
                @Test
                void given_minimal_build_file_config() throws Exception {
                        String completionFr = "Completion.fr";
                        String minimalBuildFileConfig = createFregeSection(
                                        fregeBuilder.version("'3.25.84'").release("'3.25alpha'").build());
                        setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr, minimalBuildFileConfig);

                        BuildResult result = runGradleTask(DEPS_FREGE_TASK_NAME, "-q");
                        assertTrue(project.getTasks().getByName(DEPS_FREGE_TASK_NAME) instanceof DependencyFregeTask);
                        assertEquals(SUCCESS, result.task(":" + DEPS_FREGE_TASK_NAME).getOutcome());
                        assertTrue(result.getOutput().contains("frege3.25.84.jar"));
                }

                @Test
                void given_build_file_config_with_dependencies() throws Exception {
                        String minimalBuildFileConfig = createFregeSection(
                                        fregeBuilder.version("'3.25.84'").release("'3.25alpha'").build());
                        String completionFr = "Completion.fr";
                        setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr, minimalBuildFileConfig);
                        appendToFile(buildFile, String.join("\n", "repositories {", "mavenCentral()", "}"));
                        appendToFile(buildFile, String.join("\n", "dependencies {",
                                        "implementation group: 'org.json', name: 'json', version: '20211205'", "}"));

                        BuildResult result = runGradleTask(DEPS_FREGE_TASK_NAME, "-q");
                        assertTrue(project.getTasks().getByName(DEPS_FREGE_TASK_NAME) instanceof DependencyFregeTask);
                        assertEquals(SUCCESS, result.task(":" + DEPS_FREGE_TASK_NAME).getOutcome());
                        assertTrue(result.getOutput().contains("frege3.25.84.jar"));
                        assertTrue(result.getOutput().contains("org.json"));
                }
        }

        @Nested
        @TestInstance(Lifecycle.PER_CLASS)
        @IndicativeSentencesGeneration(separator = " -> ", generator = DisplayNameGenerator.ReplaceUnderscores.class)
        class Repl_frege_task_works {
                @Test
                void given_minimal_build_file_config() throws Exception {
                        String completionFr = "Completion.fr";
                        String minimalBuildFileConfig = createFregeSection(
                                        fregeBuilder.version("'3.25.84'").release("'3.25alpha'").build());
                        setupDefaultFregeProjectStructure(SIMPLE_FREGE_CODE, completionFr, minimalBuildFileConfig);

                        BuildResult result = runGradleTask(REPL_FREGE_TASK_NAME, "-q");
                        assertTrue(project.getTasks().getByName(REPL_FREGE_TASK_NAME) instanceof ReplFregeTask);
                        assertEquals(SUCCESS, result.task(":" + REPL_FREGE_TASK_NAME).getOutcome());
                        assertTrue(result.getOutput().contains("java -cp"));
                        assertTrue(result.getOutput().contains("frege3.25.84.jar"));
                }
        }
}