package com.music.service;

import org.junit.jupiter.api.AfterEach;
import org.junit.jupiter.api.BeforeAll;
import org.junit.jupiter.api.Test;

import java.io.ByteArrayOutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.nio.charset.StandardCharsets;
import java.nio.file.Files;
import java.nio.file.Path;
import java.nio.file.Paths;
import java.util.Arrays;
import java.util.List;
import java.util.concurrent.TimeUnit;

import static org.junit.jupiter.api.Assertions.*;
import static org.junit.jupiter.api.Assumptions.assumeTrue;

/**
 * {@link AudioValidationService} 的单元与集成测试。
 *
 * <p>依赖 FFprobe/FFmpeg 的测试通过 {@link #assumeFfmpegFfprobe()} 守卫，
 * 工具不可用时自动跳过。</p>
 */
class AudioValidationServiceTest {

    private static boolean FFMPEG_AVAILABLE;

    private final AudioValidationService service = new AudioValidationService();

    @BeforeAll
    static void checkFfmpegFfprobe() throws Exception {
        try {
            ProcessBuilder pb = new ProcessBuilder("ffmpeg", "-version");
            pb.redirectErrorStream(true);
            Process p = pb.start();
            boolean ok = p.waitFor(5, TimeUnit.SECONDS);
            FFMPEG_AVAILABLE = ok && p.exitValue() == 0;
            if (!ok) p.destroyForcibly();
        } catch (Exception e) {
            FFMPEG_AVAILABLE = false;
        }
        if (FFMPEG_AVAILABLE) {
            // ffprobe 通常随 ffmpeg 一起安装
            try {
                ProcessBuilder pb = new ProcessBuilder("ffprobe", "-version");
                pb.redirectErrorStream(true);
                Process p = pb.start();
                boolean ok = p.waitFor(5, TimeUnit.SECONDS);
                FFMPEG_AVAILABLE = ok && p.exitValue() == 0;
                if (!ok) p.destroyForcibly();
            } catch (Exception e) {
                FFMPEG_AVAILABLE = false;
            }
        }
    }

    private static void assumeFfmpegFfprobe() {
        assumeTrue(FFMPEG_AVAILABLE, "此测试需要 ffmpeg 和 ffprobe");
    }

    @AfterEach
    void clearProperties() {
        System.clearProperty(AudioValidationService.FFPROBE_BIN_PROPERTY);
        System.clearProperty(AudioValidationService.FFMPEG_BIN_PROPERTY);
        System.clearProperty(AudioValidationService.PROBE_TIMEOUT_PROPERTY);
        System.clearProperty(AudioValidationService.DECODE_TIMEOUT_PROPERTY);
    }

    // ========== 可执行路径解析 ==========

    @Test
    void getFfprobeCommand_defaultIsFfprobe() {
        assertEquals("ffprobe", service.getFfprobeCommand());
    }

    @Test
    void getFfprobeCommand_respectsSystemProperty() {
        System.setProperty(AudioValidationService.FFPROBE_BIN_PROPERTY, "/custom/ffprobe");
        assertEquals("/custom/ffprobe", service.getFfprobeCommand());
    }

    @Test
    void getFfmpegCommand_defaultIsFfmpeg() {
        assertEquals("ffmpeg", service.getFfmpegCommand());
    }

    @Test
    void getFfmpegCommand_respectsSystemProperty() {
        System.setProperty(AudioValidationService.FFMPEG_BIN_PROPERTY, "/custom/ffmpeg");
        assertEquals("/custom/ffmpeg", service.getFfmpegCommand());
    }

    // ========== 超时解析 ==========

    @Test
    void resolveProbeTimeout_default() {
        assertEquals(30, service.resolveProbeTimeout());
    }

    @Test
    void resolveProbeTimeout_respectsSystemProperty() {
        System.setProperty(AudioValidationService.PROBE_TIMEOUT_PROPERTY, "15");
        assertEquals(15, service.resolveProbeTimeout());
    }

    @Test
    void resolveProbeTimeout_ignoresInvalidProperty() {
        System.setProperty(AudioValidationService.PROBE_TIMEOUT_PROPERTY, "not-a-number");
        assertEquals(30, service.resolveProbeTimeout());
    }

    @Test
    void resolveDecodeTimeout_default() {
        assertEquals(300, service.resolveDecodeTimeout());
    }

    @Test
    void resolveDecodeTimeout_respectsSystemProperty() {
        System.setProperty(AudioValidationService.DECODE_TIMEOUT_PROPERTY, "60");
        assertEquals(60, service.resolveDecodeTimeout());
    }

    @Test
    void resolveDecodeTimeout_ignoresInvalidProperty() {
        System.setProperty(AudioValidationService.DECODE_TIMEOUT_PROPERTY, "");
        assertEquals(300, service.resolveDecodeTimeout());
    }

    // ========== 超时解析（零值/负值回退） ==========

    @Test
    void resolveProbeTimeout_negativeFallsBackToDefault() {
        System.setProperty(AudioValidationService.PROBE_TIMEOUT_PROPERTY, "-1");
        assertEquals(30, service.resolveProbeTimeout());
    }

    @Test
    void resolveProbeTimeout_zeroFallsBackToDefault() {
        System.setProperty(AudioValidationService.PROBE_TIMEOUT_PROPERTY, "0");
        assertEquals(30, service.resolveProbeTimeout());
    }

    @Test
    void resolveDecodeTimeout_negativeFallsBackToDefault() {
        System.setProperty(AudioValidationService.DECODE_TIMEOUT_PROPERTY, "-5");
        assertEquals(300, service.resolveDecodeTimeout());
    }

    @Test
    void resolveDecodeTimeout_zeroFallsBackToDefault() {
        System.setProperty(AudioValidationService.DECODE_TIMEOUT_PROPERTY, "0");
        assertEquals(300, service.resolveDecodeTimeout());
    }

    // ========== ValidationResult ==========

    @Test
    void validationResult_diagnosticCappedAtMaxLength() {
        String longDiag = new String(new char[600]).replace('\0', 'X');
        AudioValidationService.ValidationResult r =
                new AudioValidationService.ValidationResult(false, longDiag);
        assertEquals(512, r.getDiagnostic().length());
        assertFalse(r.isValid());
    }

    @Test
    void validationResult_nullDiagnosticBecomesEmpty() {
        AudioValidationService.ValidationResult r =
                new AudioValidationService.ValidationResult(true, null);
        assertTrue(r.isValid());
        assertEquals("", r.getDiagnostic());
    }

    // ========== 集成测试（需要 FFmpeg + FFprobe） ==========

    @Test
    void validMp3_passesValidation() throws Exception {
        assumeFfmpegFfprobe();
        Path tmpDir = Files.createTempDirectory("val-test-");
        try {
            Path mp3 = createValidMp3(tmpDir, "test.mp3");
            AudioValidationService.ValidationResult r = service.validate(mp3);
            assertTrue(r.isValid(), "有效 MP3 应通过验证，诊断: " + r.getDiagnostic());
        } finally {
            deleteDirectory(tmpDir);
        }
    }

    @Test
    void nonAudioFile_failsProbe() throws Exception {
        assumeFfmpegFfprobe();
        Path tmpDir = Files.createTempDirectory("val-test-");
        try {
            Path garbage = tmpDir.resolve("notaudio.mp3");
            Files.write(garbage, new byte[]{0, 1, 2, 3, 4, 5, 6, 7, 8, 9});
            AudioValidationService.ValidationResult r = service.validate(garbage);
            assertFalse(r.isValid(), "非音频文件应验证失败");
        } finally {
            deleteDirectory(tmpDir);
        }
    }

    @Test
    void decode_failsWhenFfmpegExitsNonZero() throws Exception {
        assumeFfmpegFfprobe();
        Path tmpDir = Files.createTempDirectory("val-test-");
        try {
            Path mp3 = createValidMp3(tmpDir, "test.mp3");
            // 使用 /bin/false 模拟 ffmpeg 解码失败（ffprobe 使用真实工具先通过探测）
            System.setProperty(AudioValidationService.FFMPEG_BIN_PROPERTY, "/bin/false");
            AudioValidationService.ValidationResult r = service.validate(mp3);
            assertFalse(r.isValid(), "ffmpeg 退出码非零时应验证失败");
            assertTrue(r.getDiagnostic().contains("音频解码失败"),
                    "诊断信息应包含解码失败提示，实际: " + r.getDiagnostic());
        } finally {
            deleteDirectory(tmpDir);
        }
    }

    @Test
    void decode_failsWhenOutputNonEmptyEvenIfExitZero() throws Exception {
        assumeFfmpegFfprobe();
        Path tmpDir = Files.createTempDirectory("val-test-");
        try {
            Path mp3 = createValidMp3(tmpDir, "test.mp3");
            // 创建一个模拟脚本：输出错误诊断到 stderr 但退出码为 0
            // 这模拟了 FFmpeg 6.1.1 中部分解码错误（如 invalid residual）
            // 仅输出到 error 级别而不设置非零退出码的情况
            Path fakeFfmpeg = tmpDir.resolve("fake_ffmpeg.sh");
            Files.write(fakeFfmpeg, Arrays.asList(
                    "#!/bin/sh",
                    "echo 'decoder error: invalid residual' >&2",
                    "exit 0"
            ));
            fakeFfmpeg.toFile().setExecutable(true);

            System.setProperty(AudioValidationService.FFMPEG_BIN_PROPERTY, fakeFfmpeg.toString());

            AudioValidationService.ValidationResult r = service.validate(mp3);
            assertFalse(r.isValid(),
                    "ffmpeg 退出码 0 但有 error 输出时应验证失败");
            assertTrue(r.getDiagnostic().contains("音频解码失败"),
                    "诊断信息应包含解码失败提示，实际: " + r.getDiagnostic());
            assertTrue(r.getDiagnostic().contains("invalid residual"),
                    "诊断信息应包含原始的 error 输出，实际: " + r.getDiagnostic());
        } finally {
            deleteDirectory(tmpDir);
        }
    }

    @Test
    void truncatedFile_failsProbe() throws Exception {
        assumeFfmpegFfprobe();
        Path tmpDir = Files.createTempDirectory("val-test-");
        try {
            Path mp3 = createValidMp3(tmpDir, "trunc_test.mp3");
            // 截断到 100 字节，保留 ID3v2 标签头但音频数据已不完整
            long truncatedSize = Math.min(Files.size(mp3), 100);
            try (java.io.RandomAccessFile raf = new java.io.RandomAccessFile(mp3.toFile(), "rw")) {
                raf.setLength(truncatedSize);
            }
            AudioValidationService.ValidationResult r = service.validate(mp3);
            assertFalse(r.isValid(), "截断的文件应验证失败");
        } finally {
            deleteDirectory(tmpDir);
        }
    }

    @Test
    void missingExecutable_failsGracefully() throws Exception {
        Path tmpDir = Files.createTempDirectory("val-test-");
        try {
            Path mp3 = createValidMp3(tmpDir, "test.mp3");
            // 使用不存在的 ffprobe 路径
            System.setProperty(AudioValidationService.FFPROBE_BIN_PROPERTY, "/nonexistent/ffprobe");
            AudioValidationService.ValidationResult r = service.validate(mp3);
            assertFalse(r.isValid(), "ffprobe 不可用时验证应失败");
            assertTrue(r.getDiagnostic().contains("FFprobe 执行失败"));
        } finally {
            deleteDirectory(tmpDir);
        }
    }

    @Test
    void missingFfmpeg_failsDecodeGracefully() throws Exception {
        Path tmpDir = Files.createTempDirectory("val-test-");
        try {
            Path mp3 = createValidMp3(tmpDir, "test.mp3");
            // 使用不存在的 ffmpeg 路径
            System.setProperty(AudioValidationService.FFMPEG_BIN_PROPERTY, "/nonexistent/ffmpeg");
            AudioValidationService.ValidationResult r = service.validate(mp3);
            assertFalse(r.isValid(), "ffmpeg 不可用时验证应失败");
            assertTrue(r.getDiagnostic().contains("FFmpeg 执行失败"));
        } finally {
            deleteDirectory(tmpDir);
        }
    }

    // ========== 超时集成测试（需要 FFmpeg + FFprobe） ==========

    @Test
    void probe_timesOut() throws Exception {
        assumeFfmpegFfprobe();
        Path tmpDir = Files.createTempDirectory("val-test-");
        try {
            Path mp3 = createValidMp3(tmpDir, "test.mp3");

            // 创建一个忽略参数并 sleep 30s 的挂起脚本
            Path hangScript = tmpDir.resolve("hang.sh");
            Files.write(hangScript, Arrays.asList("#!/bin/sh", "sleep 30"));
            hangScript.toFile().setExecutable(true);

            System.setProperty(AudioValidationService.FFPROBE_BIN_PROPERTY, hangScript.toString());
            System.setProperty(AudioValidationService.PROBE_TIMEOUT_PROPERTY, "1");

            AudioValidationService.ValidationResult r = service.validate(mp3);
            assertFalse(r.isValid(), "探测超时应验证失败");
            assertTrue(r.getDiagnostic().contains("音频探测超时"),
                    "诊断应提示超时，实际: " + r.getDiagnostic());
        } finally {
            deleteDirectory(tmpDir);
        }
    }

    @Test
    void decode_timesOut() throws Exception {
        assumeFfmpegFfprobe();
        Path tmpDir = Files.createTempDirectory("val-test-");
        try {
            Path mp3 = createValidMp3(tmpDir, "test.mp3");

            // 创建一个忽略参数并 sleep 30s 的挂起脚本
            Path hangScript = tmpDir.resolve("hang.sh");
            Files.write(hangScript, Arrays.asList("#!/bin/sh", "sleep 30"));
            hangScript.toFile().setExecutable(true);

            System.setProperty(AudioValidationService.FFMPEG_BIN_PROPERTY, hangScript.toString());
            System.setProperty(AudioValidationService.DECODE_TIMEOUT_PROPERTY, "1");

            AudioValidationService.ValidationResult r = service.validate(mp3);
            assertFalse(r.isValid(), "解码超时应验证失败");
            assertTrue(r.getDiagnostic().contains("音频解码超时"),
                    "诊断应提示解码超时，实际: " + r.getDiagnostic());
        } finally {
            deleteDirectory(tmpDir);
        }
    }

    @Test
    void decodeCommand_usesXerrorAndMapArgs() throws Exception {
        assumeFfmpegFfprobe();
        Path tmpDir = Files.createTempDirectory("val-test-");
        try {
            Path mp3 = createValidMp3(tmpDir, "test.mp3");
            List<String> args = service.getDecodeCommandArgs(mp3);
            assertTrue(args.contains("-xerror"),
                    "decode 命令应包含 -xerror，实际参数: " + args);
            assertTrue(args.contains("-map"),
                    "decode 命令应包含 -map，实际参数: " + args);
            int mapIndex = args.indexOf("-map");
            assertTrue(mapIndex >= 0 && mapIndex + 1 < args.size(),
                    "-map 参数后应有值");
            assertEquals("0:a:0", args.get(mapIndex + 1),
                    "-map 参数应指定 0:a:0");
            assertTrue(args.contains("-f"),
                    "decode 命令应包含 -f");
            assertTrue(args.contains("null"),
                    "解码 muxer 应为 null");
        } finally {
            deleteDirectory(tmpDir);
        }
    }

    // ========== 排空测试（大量输出不阻塞） ==========

    @Test
    void drainer_doesNotDeadlockWithVerboseOutput() throws Exception {
        assumeFfmpegFfprobe();
        Path tmpDir = Files.createTempDirectory("val-test-");
        try {
            // 创建一个输出远大于操作系统管道缓冲区（通常 64KB）的脚本
            Path verboseScript = tmpDir.resolve("verbose.sh");
            Files.write(verboseScript, Arrays.asList(
                    "#!/bin/sh",
                    "# 输出 ~200KB 数据以填满管道缓冲区",
                    "yes A | head -c 200000",
                    "exit 0"
            ));
            verboseScript.toFile().setExecutable(true);

            System.setProperty(AudioValidationService.FFPROBE_BIN_PROPERTY, verboseScript.toString());
            System.setProperty(AudioValidationService.PROBE_TIMEOUT_PROPERTY, "10");

            Path mp3 = createValidMp3(tmpDir, "test.mp3");

            // 需要 ffprobe 正常可用供 decode 阶段使用，但 probe 阶段使用 verbose 脚本
            AudioValidationService.ValidationResult r = service.validate(mp3);
            // verbose 脚本输出大量 'A'，不含 "audio"，预计探测失败
            assertFalse(r.isValid(), "非音频输出应验证失败");
            // 诊断信息必须被截断到 MAX_DIAGNOSTIC_LENGTH
            assertTrue(r.getDiagnostic().length() <= 512,
                    "诊断信息不应超过 512 字节，实际: " + r.getDiagnostic().length());
        } finally {
            deleteDirectory(tmpDir);
        }
    }

    // ========== 中断清理测试 ==========

    @Test
    void interruptDuringProbe_cleansUpAndReinterrupts() throws Exception {
        Path tmpDir = Files.createTempDirectory("val-test-");
        try {
            Path hangScript = tmpDir.resolve("hang.sh");
            Files.write(hangScript, Arrays.asList("#!/bin/sh", "sleep 30"));
            hangScript.toFile().setExecutable(true);

            System.setProperty(AudioValidationService.FFPROBE_BIN_PROPERTY, hangScript.toString());
            System.setProperty(AudioValidationService.PROBE_TIMEOUT_PROPERTY, "10");

            Path mp3 = createValidMp3(tmpDir, "test.mp3");

            // 先设置中断标志，再调用 validate
            // p.waitFor(timeout, ...) 会在中断标志已设置时立即抛出 InterruptedException
            Thread.currentThread().interrupt();
            AudioValidationService.ValidationResult r = service.validate(mp3);

            assertFalse(r.isValid(), "中断后验证应失败");
            // runProcess 应在清理后重新设置中断标志
            assertTrue(Thread.interrupted(), "中断标志应被保留并由 Thread.interrupted() 清除");
        } finally {
            Thread.interrupted(); // 清除主线程残留中断
            deleteDirectory(tmpDir);
        }
    }

    // ========== FFprobe 后备元数据读取 ==========

    @Test
    void getMetadataCommandArgs_usesStructuredJson() {
        Path f = Paths.get("/tmp/song.m4a");
        List<String> args = service.getMetadataCommandArgs(f);
        assertTrue(args.contains("-print_format"));
        assertTrue(args.contains("json"));
        assertTrue(args.contains("-show_format"));
        assertTrue(args.contains("-show_streams"));
        // 绝不使用任何人类可读文本或文件名猜测选项
        assertFalse(args.contains("-of"));
        assertEquals(f.toAbsolutePath().toString(), args.get(args.size() - 1));
    }

    @Test
    void readMetadata_returnsFullTags() throws Exception {
        assumeFfmpegFfprobe();
        Path tmpDir = Files.createTempDirectory("probe-meta-");
        try {
            Path m4a = createTaggedM4a(tmpDir, "song.m4a",
                    "ProbeTitle", "ProbeArtist", "ProbeAlbum");

            AudioValidationService.ProbeMetadata meta = service.readMetadata(m4a);
            assertTrue(meta.isAvailable(), "应成功读取元数据");
            assertEquals("ProbeTitle", meta.getFirst("title"));
            assertEquals("ProbeArtist", meta.getFirst("artist"));
            assertEquals("ProbeAlbum", meta.getFirst("album"));
        } finally {
            deleteDirectory(tmpDir);
        }
    }

    @Test
    void readMetadata_missingAlbumReturnsEmpty() throws Exception {
        assumeFfmpegFfprobe();
        Path tmpDir = Files.createTempDirectory("probe-meta-");
        try {
            // 仅写 title/artist，故意不写 album
            Path m4a = tmpDir.resolve("noalbum.m4a");
            ProcessBuilder pb = new ProcessBuilder(
                    "ffmpeg", "-y", "-f", "lavfi", "-i", "anullsrc=r=44100:cl=mono",
                    "-t", "0.3", "-c:a", "aac",
                    "-metadata", "title=T", "-metadata", "artist=A",
                    m4a.toAbsolutePath().toString());
            pb.redirectErrorStream(true);
            Process p = pb.start();
            readAllBytes(p.getInputStream());
            p.waitFor(15, TimeUnit.SECONDS);

            AudioValidationService.ProbeMetadata meta = service.readMetadata(m4a);
            assertTrue(meta.isAvailable());
            assertEquals("", meta.getFirst("album"), "缺失的 album 应返回空字符串");
        } finally {
            deleteDirectory(tmpDir);
        }
    }

    @Test
    void readMetadata_nonAudioFileUnavailable() throws Exception {
        assumeFfmpegFfprobe();
        Path tmpDir = Files.createTempDirectory("probe-meta-");
        try {
            Path bogus = tmpDir.resolve("bogus.m4a");
            Files.write(bogus, "not an audio file".getBytes(StandardCharsets.UTF_8));

            AudioValidationService.ProbeMetadata meta = service.readMetadata(bogus);
            assertFalse(meta.isAvailable(), "无法识别的文件应返回 unavailable");
        } finally {
            deleteDirectory(tmpDir);
        }
    }

    @Test
    void readMetadata_ffprobeFailureUnavailable() {
        // 强制 ffprobe 指向失败命令
        System.setProperty(AudioValidationService.FFPROBE_BIN_PROPERTY, "/bin/false");
        AudioValidationService.ProbeMetadata meta =
                service.readMetadata(Paths.get("/tmp/whatever.m4a"));
        assertFalse(meta.isAvailable(), "ffprobe 失败应返回 unavailable");
    }

    /**
     * 使用 FFmpeg 创建一个带标签的有效短 M4A（AAC）文件。
     */
    private static Path createTaggedM4a(Path dir, String fileName,
                                        String title, String artist, String album) throws Exception {
        Path out = dir.resolve(fileName);
        ProcessBuilder pb = new ProcessBuilder(
                "ffmpeg", "-y", "-f", "lavfi", "-i", "anullsrc=r=44100:cl=mono",
                "-t", "0.3", "-c:a", "aac",
                "-metadata", "title=" + title,
                "-metadata", "artist=" + artist,
                "-metadata", "album=" + album,
                out.toAbsolutePath().toString());
        pb.redirectErrorStream(true);
        Process p = pb.start();
        readAllBytes(p.getInputStream());
        boolean finished = p.waitFor(15, TimeUnit.SECONDS);
        if (!finished) {
            p.destroyForcibly();
            throw new RuntimeException("ffmpeg 创建 M4A 超时");
        }
        if (p.exitValue() != 0) {
            throw new RuntimeException("ffmpeg 创建 M4A 失败 (exit=" + p.exitValue() + ")");
        }
        return out;
    }

    // ========== 帮助方法 ==========

    /**
     * 使用 FFmpeg 创建一个带标签的有效短 MP3 文件。
     */
    private static Path createValidMp3(Path dir, String fileName) throws Exception {
        Path out = dir.resolve(fileName);
        ProcessBuilder pb = new ProcessBuilder(
                "ffmpeg", "-y",
                "-f", "lavfi", "-i", "sine=frequency=440:duration=0.2",
                "-b:a", "32k",
                "-write_xing", "0",
                "-id3v2_version", "3",
                "-metadata", "title=TestTitle",
                "-metadata", "artist=TestArtist",
                "-metadata", "album=TestAlbum",
                out.toAbsolutePath().toString()
        );
        pb.redirectErrorStream(true);
        Process p = pb.start();
        readAllBytes(p.getInputStream());
        boolean finished = p.waitFor(15, TimeUnit.SECONDS);
        if (!finished) {
            p.destroyForcibly();
            throw new RuntimeException("ffmpeg 创建 MP3 超时");
        }
        if (p.exitValue() != 0) {
            throw new RuntimeException("ffmpeg 创建 MP3 失败 (exit=" + p.exitValue() + ")");
        }
        return out;
    }

    private static byte[] readAllBytes(InputStream is) throws IOException {
        ByteArrayOutputStream buf = new ByteArrayOutputStream();
        byte[] tmp = new byte[4096];
        int n;
        while ((n = is.read(tmp)) != -1) {
            buf.write(tmp, 0, n);
        }
        return buf.toByteArray();
    }

    private static void deleteDirectory(Path dir) {
        try {
            if (Files.exists(dir)) {
                Files.walk(dir)
                        .sorted((a, b) -> -a.compareTo(b))
                        .forEach(p -> {
                            try { Files.deleteIfExists(p); } catch (Exception ignored) {}
                        });
            }
        } catch (Exception ignored) {}
    }
}