/* ViewPanel —— 最小注入器
 *
 * 依据（REA 对 Contents/MacOS/Spine 的实测）：
 *   · 该二进制导入 _dlopen/_dlsym/_dlerror，__la_symbol_ptr 里有 _dlsym 槽位，
 *     且没有直接链接 _JNI_CreateJavaVM —— JNI 入口是运行期 dlopen+dlsym 拿的，
 *     所以重绑定 _dlsym 是有效钩子点。
 *   · ad-hoc 签名、无 hardened runtime、无 entitlements —— DYLD_INSERT_LIBRARIES 可用。
 *
 * 本文件只做三件事：
 *   1) 重绑定 _dlsym（含后加载的 libjvm）
 *   2) 拦 JNI_CreateJavaVM
 *   3) JVM 起来后，把我们的类 DefineClass 进编辑器自己的类加载器，再调用它的 main
 *
 * 这里没有任何 UI 代码：面板是纯 Java / Scene2D 实现的。
 */

#include <dirent.h>
#include <dlfcn.h>
#include <jni.h>
#include <mach-o/dyld.h>
#include <mach-o/loader.h>
#include <mach-o/nlist.h>
#include <pthread.h>
#include <stdarg.h>
#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <sys/mman.h>
#include <sys/stat.h>
#include <unistd.h>

#define VP_LOG "/tmp/spine-viewpanel.log"
#define VP_DEFAULT_CLASSES "/tmp/spine-viewpanel/classes"
#define VP_DEFAULT_MAIN "com/spineview/SceneScan"

static void vp_log(const char *format, ...) {
    FILE *file = fopen(VP_LOG, "a");
    if (!file) return;
    fprintf(file, "[pid %d] ", (int)getpid());
    va_list arguments;
    va_start(arguments, format);
    vfprintf(file, format, arguments);
    va_end(arguments);
    fputc('\n', file);
    fclose(file);
}

typedef void *(*dlsym_fn)(void *, const char *);
typedef jint (*create_vm_fn)(JavaVM **, void **, void *);

static dlsym_fn real_dlsym = NULL;
static create_vm_fn real_create_vm = NULL;
static JavaVM *g_vm = NULL;
static jobject g_editor_loader = NULL; /* 编辑器自己的 ClassLoader 实例 */
static jclass g_panel_class = NULL;    /* com.spineview.SceneScan 的全局引用 */
static jmethodID g_on_render = NULL;   /* SceneScan.onRenderThread() */
static char g_classes_dir[4096];
static char g_main_class[512];
static pthread_mutex_t g_lock = PTHREAD_MUTEX_INITIALIZER;

typedef void (*swap_fn)(JNIEnv *, jclass, jlong);
static swap_fn real_swap = NULL;
static int g_swap_calls = 0;

/* 编辑器用它自己的类加载器加载了这些保名的 libGDX 控件类（REA 运行时证据），
 * 拿它们的 Class 对象就能反推出编辑器类加载器。 */
static const char *kEditorAnchorClasses[] = {
    "com/badlogic/gdx/scenes/scene2d/ui/TextButton",
    "com/badlogic/gdx/scenes/scene2d/ui/Label",
    "com/badlogic/gdx/scenes/scene2d/ui/ImageTextButton",
    "com/badlogic/gdx/scenes/scene2d/ui/Window",
    "com/badlogic/jglfw/Glfw",
};

/* ---------- 读取我们的 .class ---------- */

static jclass vp_define_file(JNIEnv *env, jobject loader, const char *path) {
    FILE *file = fopen(path, "rb");
    if (!file) return NULL;
    fseek(file, 0, SEEK_END);
    long size = ftell(file);
    fseek(file, 0, SEEK_SET);
    if (size <= 0) { fclose(file); return NULL; }
    unsigned char *buffer = malloc((size_t)size);
    if (!buffer) { fclose(file); return NULL; }
    size_t read = fread(buffer, 1, (size_t)size, file);
    fclose(file);
    if (read != (size_t)size) { free(buffer); return NULL; }
    jclass defined = (*env)->DefineClass(env, NULL, loader, (const jbyte *)buffer, (jsize)size);
    free(buffer);
    if ((*env)->ExceptionCheck(env)) {
        vp_log("DefineClass 抛出异常: %s", path);
        (*env)->ExceptionDescribe(env);
        (*env)->ExceptionClear(env);
        return NULL;
    }
    return defined;
}

static jclass vp_define_directory(JNIEnv *env, jobject loader, const char *root,
                                  const char *relative, const char *main_internal) {
    jclass found = NULL;
    char path[4096];
    if (relative[0]) snprintf(path, sizeof(path), "%s/%s", root, relative);
    else snprintf(path, sizeof(path), "%s", root);
    DIR *directory = opendir(path);
    if (!directory) return NULL;
    struct dirent *entry;
    while ((entry = readdir(directory)) != NULL) {
        if (strcmp(entry->d_name, ".") == 0 || strcmp(entry->d_name, "..") == 0) continue;
        char child_relative[4096];
        if (relative[0]) snprintf(child_relative, sizeof(child_relative), "%s/%s", relative, entry->d_name);
        else snprintf(child_relative, sizeof(child_relative), "%s", entry->d_name);
        char child_path[4096];
        snprintf(child_path, sizeof(child_path), "%s/%s", root, child_relative);
        struct stat info;
        if (stat(child_path, &info) != 0) continue;
        if (S_ISDIR(info.st_mode)) {
            jclass nested = vp_define_directory(env, loader, root, child_relative, main_internal);
            if (nested) found = nested;
            continue;
        }
        size_t length = strlen(child_relative);
        if (length <= 6 || strcmp(child_relative + length - 6, ".class") != 0) continue;
        char internal_name[4096];
        snprintf(internal_name, sizeof(internal_name), "%s", child_relative);
        internal_name[length - 6] = '\0';
        jclass defined = vp_define_file(env, loader, child_path);
        vp_log("define %s -> %s", internal_name, defined ? "ok" : "failed");
        if (defined && main_internal && strcmp(internal_name, main_internal) == 0) found = defined;
    }
    closedir(directory);
    return found;
}

/* ---------- 在编辑器自己的类加载器里加载并执行我们的类 ---------- */

/* 把我们的类定义进调用方传入的加载器（也就是编辑器自己的那个），返回入口类。
 * 目的是让我们的代码和编辑器处在同一个类命名空间里，能直接按名字找它的类。 */
static jclass VPC_defineIntoLoader(JNIEnv *env, jclass clazz, jobject loader) {
    (void)clazz;
    if (!env || !loader) return NULL;
    jclass defined = vp_define_directory(env, loader, g_classes_dir, "", g_main_class);
    vp_log("defineIntoLoader: %s", defined ? "已定义" : "失败");
    return defined;
}

static void *vp_run_thread(void *unused) {
    (void)unused;
    /* 等编辑器把保名的控件类加载进来（启动后几百毫秒到几秒）。 */
    jobject loader = NULL;
    for (int attempt = 0; attempt < 120 && !loader; attempt++) {
        pthread_mutex_lock(&g_lock);
        loader = g_editor_loader;
        pthread_mutex_unlock(&g_lock);
        if (!loader) usleep(200000);
    }
    JNIEnv *env = NULL;
    if (!g_vm || (*g_vm)->AttachCurrentThread(g_vm, (void **)&env, NULL) != JNI_OK || !env) {
        vp_log("run: AttachCurrentThread 失败");
        return NULL;
    }
    if (!loader) {
        /* 有些进程不触发 dlsym("Java_...")，抓不到编辑器加载器。
         * 退一步用系统类加载器：我们的类定义进去照样能跑，只是看不到编辑器的私有类。 */
        jclass class_loader_class = (*env)->FindClass(env, "java/lang/ClassLoader");
        jmethodID get_system = class_loader_class
            ? (*env)->GetStaticMethodID(env, class_loader_class, "getSystemClassLoader",
                                        "()Ljava/lang/ClassLoader;") : NULL;
        if (get_system) loader = (*env)->CallStaticObjectMethod(env, class_loader_class, get_system);
        if ((*env)->ExceptionCheck(env)) { (*env)->ExceptionDescribe(env); (*env)->ExceptionClear(env); loader = NULL; }
        vp_log("run: 没抓到编辑器加载器，改用系统类加载器 -> %p", loader);
    }
    if (!loader) { vp_log("run: 拿不到任何类加载器，放弃"); return NULL; }
    {
        jclass object_class = (*env)->FindClass(env, "java/lang/Object");
        jmethodID to_string = object_class
            ? (*env)->GetMethodID(env, object_class, "toString", "()Ljava/lang/String;") : NULL;
        jstring text = to_string ? (jstring)(*env)->CallObjectMethod(env, loader, to_string) : NULL;
        const char *chars = text ? (*env)->GetStringUTFChars(env, text, NULL) : NULL;
        vp_log("run: 编辑器类加载器 = %s", chars ? chars : "(未知)");
        if (chars) (*env)->ReleaseStringUTFChars(env, text, chars);
    }

    jclass main_class = vp_define_directory(env, loader, g_classes_dir, "", g_main_class);
    if (!main_class) { vp_log("run: 没有定义到入口类 %s", g_main_class); return NULL; }

    {
        JNINativeMethod methods[] = {
            { "defineIntoLoader", "(Ljava/lang/ClassLoader;)Ljava/lang/Class;", (void *)VPC_defineIntoLoader },
        };
        if ((*env)->RegisterNatives(env, main_class, methods, 1) != JNI_OK) {
            vp_log("run: 注册 defineIntoLoader 失败");
            if ((*env)->ExceptionCheck(env)) { (*env)->ExceptionDescribe(env); (*env)->ExceptionClear(env); }
        } else {
            vp_log("run: 已注册 defineIntoLoader");
        }
    }

    g_panel_class = (jclass)(*env)->NewGlobalRef(env, main_class);
    g_on_render = (*env)->GetStaticMethodID(env, main_class, "onRenderThread", "()V");
    if (!g_on_render) {
        vp_log("run: 找不到 onRenderThread");
        if ((*env)->ExceptionCheck(env)) { (*env)->ExceptionDescribe(env); (*env)->ExceptionClear(env); }
    }
    /* 把进程号写进去：日志里要能区分启动器进程和编辑器进程。 */
    {
        jfieldID pid_field = (*env)->GetStaticFieldID(env, main_class, "pid", "J");
        if (pid_field) {
            (*env)->SetStaticLongField(env, main_class, pid_field, (jlong)getpid());
            vp_log("run: 已把 pid=%d 写进 Java", (int)getpid());
        } else {
            if ((*env)->ExceptionCheck(env)) (*env)->ExceptionClear(env);
            vp_log("run: 没找到 pid 静态字段");
        }
    }

    jclass string_class = (*env)->FindClass(env, "java/lang/String");
    jobjectArray arguments = (*env)->NewObjectArray(env, 0, string_class, NULL);
    jmethodID main_method = (*env)->GetStaticMethodID(env, main_class, "main", "([Ljava/lang/String;)V");
    if (!main_method) {
        vp_log("run: 找不到 main([Ljava/lang/String;)V");
        if ((*env)->ExceptionCheck(env)) { (*env)->ExceptionDescribe(env); (*env)->ExceptionClear(env); }
        return NULL;
    }
    vp_log("run: 调用 %s.main", g_main_class);
    (*env)->CallStaticVoidMethod(env, main_class, main_method, arguments);
    if ((*env)->ExceptionCheck(env)) {
        vp_log("run: main 抛出异常");
        (*env)->ExceptionDescribe(env);
        (*env)->ExceptionClear(env);
    }
    return NULL;
}

static void vp_start_thread(void) {
    pthread_t thread;
    if (pthread_create(&thread, NULL, vp_run_thread, NULL) == 0) {
        pthread_detach(thread);
        vp_log("已启动注入线程");
    } else {
        vp_log("线程创建失败");
    }
}

typedef jint (*get_created_vms_fn)(JavaVM **, jsize, jsize *);

/* 有些进程（例如 3.8.99 的 x86 编辑器）是从启动器进程继承 JVM 的，
 * 根本不会调用 JNI_CreateJavaVM —— 钩子自然不会触发。
 * 这里改用 JNI_GetCreatedJavaVMs 去取已经存在的 VM。 */
static void *vp_find_existing_vm_thread(void *unused) {
    (void)unused;
    for (int attempt = 0; attempt < 1200; attempt++) {
        if (g_vm) return NULL;
        get_created_vms_fn get_vms = real_dlsym
            ? (get_created_vms_fn)real_dlsym(RTLD_DEFAULT, "JNI_GetCreatedJavaVMs") : NULL;
        if (get_vms) {
            JavaVM *vm = NULL;
            jsize count = 0;
            if (get_vms(&vm, 1, &count) == JNI_OK && count > 0 && vm) {
                g_vm = vm;
                vp_log("用 JNI_GetCreatedJavaVMs 拿到已存在的 JVM，开始注入");
                vp_start_thread();
                return NULL;
            }
        }
        usleep(500000);
    }
    return NULL;
}

static void vp_start_vm_watch(void) {
    pthread_t thread;
    if (pthread_create(&thread, NULL, vp_find_existing_vm_thread, NULL) == 0) pthread_detach(thread);
}

/* ---------- 抓编辑器类加载器 ---------- */

/* 编辑器在给自己绑定原生方法时会 dlsym("Java_...")；此刻调用 FindClass，
 * 正好落在编辑器自己的类加载上下文里，用它反推编辑器类加载器。只观察，不改返回值。 */
static void vp_try_capture(const char *symbol) {
    pthread_mutex_lock(&g_lock);
    int need = (g_editor_loader == NULL);
    pthread_mutex_unlock(&g_lock);
    if (!need || !g_vm) return;

    JNIEnv *env = NULL;
    if ((*g_vm)->GetEnv(g_vm, (void **)&env, JNI_VERSION_1_6) != JNI_OK || !env) return;

    jclass class_class = (*env)->FindClass(env, "java/lang/Class");
    jmethodID get_class_loader = class_class
        ? (*env)->GetMethodID(env, class_class, "getClassLoader", "()Ljava/lang/ClassLoader;") : NULL;

    for (size_t index = 0; index < sizeof(kEditorAnchorClasses) / sizeof(kEditorAnchorClasses[0]); index++) {
        jclass found = (*env)->FindClass(env, kEditorAnchorClasses[index]);
        if (!found) { (*env)->ExceptionClear(env); continue; }
        jobject loader = get_class_loader ? (*env)->CallObjectMethod(env, found, get_class_loader) : NULL;
        if (!loader || (*env)->ExceptionCheck(env)) {
            (*env)->ExceptionClear(env);
            /* FindClass 落在 bootstrap/系统加载器上时 getClassLoader() 会是 null，
             * 这时改用当前 Java 线程的上下文加载器（编辑器线程的上下文就是编辑器加载器）。 */
            jclass thread_class = (*env)->FindClass(env, "java/lang/Thread");
            jmethodID current = thread_class
                ? (*env)->GetStaticMethodID(env, thread_class, "currentThread", "()Ljava/lang/Thread;") : NULL;
            jmethodID context = thread_class
                ? (*env)->GetMethodID(env, thread_class, "getContextClassLoader", "()Ljava/lang/ClassLoader;") : NULL;
            if (current && context) {
                jobject thread = (*env)->CallStaticObjectMethod(env, thread_class, current);
                if (thread) loader = (*env)->CallObjectMethod(env, thread, context);
                if ((*env)->ExceptionCheck(env)) { (*env)->ExceptionClear(env); loader = NULL; }
            }
        }
        if (!loader) {
            vp_log("锚点 %s 的加载器为空，继续试下一个", kEditorAnchorClasses[index]);
            continue;
        }
        pthread_mutex_lock(&g_lock);
        if (!g_editor_loader) {
            g_editor_loader = (*env)->NewGlobalRef(env, loader);
            char message[512];
            snprintf(message, sizeof(message), "捕获编辑器类加载器（锚点 %s，触发符号 %s）",
                     kEditorAnchorClasses[index], symbol ? symbol : "(null)");
            pthread_mutex_unlock(&g_lock);
            vp_log("%s", message);
            return;
        }
        pthread_mutex_unlock(&g_lock);
        return;
    }
}

/* ---------- JVM 创建拦截 ---------- */

static jint vp_create_vm(JavaVM **pvm, void **penv, void *args) {
    vp_log("拦截到 JNI_CreateJavaVM");
    jint result = real_create_vm ? real_create_vm(pvm, penv, args) : JNI_ERR;
    if (result != JNI_OK || !pvm || !*pvm) {
        vp_log("JNI_CreateJavaVM 失败: %d", (int)result);
        return result;
    }
    g_vm = *pvm;
    vp_log("JVM 已创建，等编辑器类加载器");
    vp_start_thread();
    return result;
}

/* ---------- _dlsym 重绑定 ---------- */

/* 渲染线程上的钩子：编辑器每帧调 glfwSwapBuffers 时，先问一下 Java 侧要不要装配面板。
 * 只在前若干帧回调，之后彻底安静。 */
static void vp_swap(JNIEnv *env, jclass clazz, jlong window) {
    const char *no_call = getenv("SPINE_VIEWPANEL_NO_JCALL");
    if (g_panel_class && g_on_render && env && g_swap_calls < 20000
        && !(no_call && no_call[0] == '1')) {
        g_swap_calls++;
        (*env)->CallStaticVoidMethod(env, g_panel_class, g_on_render);
        if ((*env)->ExceptionCheck(env)) {
            (*env)->ExceptionDescribe(env);
            (*env)->ExceptionClear(env);
        }
    }
    if (real_swap) real_swap(env, clazz, window);
}

static void *vp_dlsym(void *handle, const char *name) {
    if (name && strcmp(name, "JNI_CreateJavaVM") == 0) {
        if (!real_create_vm && real_dlsym) real_create_vm = (create_vm_fn)real_dlsym(handle, name);
        vp_log("dlsym: 返回注入版 JNI_CreateJavaVM");
        return (void *)vp_create_vm;
    }
    /* 只截 JNI 方法，不碰 C 函数 glfwSwapBuffers。
     * libjglfw 里两个符号都有：C 函数的签名是 (GLFWwindow*)，JNI 方法是 (JNIEnv*,jclass,jlong)。
     * 截错那个会让包装函数用错签名，直接把渲染搞坏（实测窗口全黑）。 */
    if (name && strncmp(name, "Java_", 5) == 0 && strstr(name, "glfwSwapBuffers") != NULL) {
        void *real = real_dlsym ? real_dlsym(handle, name) : NULL;
        if (!real) {
            vp_log("dlsym: %s 拿不到真实实现，不挂钩（否则会没有交换缓冲 → 黑屏）", name);
            return NULL;
        }
        /* 实测：替换这个 JNI 方法会让编辑器整窗黑屏（启动器没事），所以默认不挂。
         * 需要时用 SPINE_VIEWPANEL_SWAP=1 显式打开。 */
        const char *enable = getenv("SPINE_VIEWPANEL_SWAP");
        if (!enable || enable[0] != '1') return real;
        if (getenv("SPINE_VIEWPANEL_NO_SWAP")) return real;
        if (!real_swap) {
            real_swap = (swap_fn)real;
            void *via_default = real_dlsym(RTLD_DEFAULT, name);
            void *via_next = real_dlsym(RTLD_NEXT, name);
            vp_log("dlsym: 截住 %s  真实=%p RTLD_DEFAULT=%p RTLD_NEXT=%p",
                   name, real, via_default, via_next);
        }
        return (void *)vp_swap;
    }
    if (name && strncmp(name, "Java_", 5) == 0) vp_try_capture(name);
    return real_dlsym ? real_dlsym(handle, name) : NULL;
}

static void vp_make_writable(void *address, size_t size) {
    uintptr_t page = (uintptr_t)address & ~((uintptr_t)getpagesize() - 1);
    uintptr_t end = ((uintptr_t)address + size + getpagesize() - 1) & ~((uintptr_t)getpagesize() - 1);
    mprotect((void *)page, end - page, PROT_READ | PROT_WRITE);
}

static void vp_rebind(const struct mach_header *header, intptr_t slide) {
    if (!header || header->magic != MH_MAGIC_64) return;
    const uint8_t *image = (const uint8_t *)header;
    const struct load_command *cmd = (const struct load_command *)(image + sizeof(struct mach_header_64));
    const struct symtab_command *symtab = NULL;
    const struct dysymtab_command *dysymtab = NULL;
    const struct segment_command_64 *linkedit = NULL;

    for (uint32_t index = 0; index < header->ncmds; index++) {
        if (cmd->cmd == LC_SYMTAB) symtab = (const struct symtab_command *)cmd;
        else if (cmd->cmd == LC_DYSYMTAB) dysymtab = (const struct dysymtab_command *)cmd;
        else if (cmd->cmd == LC_SEGMENT_64) {
            const struct segment_command_64 *segment = (const struct segment_command_64 *)cmd;
            if (strcmp(segment->segname, "__LINKEDIT") == 0) linkedit = segment;
        }
        cmd = (const struct load_command *)((const uint8_t *)cmd + cmd->cmdsize);
    }
    if (!symtab || !dysymtab || !linkedit) return;

    const uintptr_t linkedit_base = (uintptr_t)(linkedit->vmaddr - linkedit->fileoff + slide);
    const struct nlist_64 *symbols = (const struct nlist_64 *)(linkedit_base + symtab->symoff);
    const char *strings = (const char *)(linkedit_base + symtab->stroff);
    const uint32_t *indirect = (const uint32_t *)(linkedit_base + dysymtab->indirectsymoff);

    cmd = (const struct load_command *)(image + sizeof(struct mach_header_64));
    for (uint32_t index = 0; index < header->ncmds; index++) {
        if (cmd->cmd != LC_SEGMENT_64) {
            cmd = (const struct load_command *)((const uint8_t *)cmd + cmd->cmdsize);
            continue;
        }
        const struct segment_command_64 *segment = (const struct segment_command_64 *)cmd;
        const struct section_64 *sections =
            (const struct section_64 *)((const uint8_t *)segment + sizeof(struct segment_command_64));
        for (uint32_t section_index = 0; section_index < segment->nsects; section_index++) {
            const struct section_64 *section = &sections[section_index];
            if (strcmp(section->sectname, "__la_symbol_ptr") != 0 &&
                strcmp(section->sectname, "__got") != 0) continue;
            if (section->reserved1 == 0) continue;
            const size_t count = section->size / sizeof(void *);
            for (size_t entry = 0; entry < count; entry++) {
                uint32_t symbol_index = indirect[section->reserved1 + entry];
                if (symbol_index >= symtab->nsyms) continue;
                const char *name = strings + symbols[symbol_index].n_un.n_strx;
                if (name && strcmp(name, "_dlsym") == 0) {
                    void **slot = (void **)((uintptr_t)section->addr + slide + entry * sizeof(void *));
                    vp_make_writable(slot, sizeof(void *));
                    *slot = vp_dlsym;
                }
            }
        }
        cmd = (const struct load_command *)((const uint8_t *)cmd + cmd->cmdsize);
    }
}

static void vp_image_added(const struct mach_header *header, intptr_t slide) {
    vp_rebind(header, slide);
}

__attribute__((constructor))
static void vp_install(void) {
    real_dlsym = (dlsym_fn)dlsym(RTLD_DEFAULT, "dlsym");
    const char *dir = getenv("SPINE_VIEWPANEL_CLASSES");
    snprintf(g_classes_dir, sizeof(g_classes_dir), "%s",
             (dir && dir[0]) ? dir : VP_DEFAULT_CLASSES);
    const char *main_class = getenv("SPINE_VIEWPANEL_MAIN");
    snprintf(g_main_class, sizeof(g_main_class), "%s",
             (main_class && main_class[0]) ? main_class : VP_DEFAULT_MAIN);
    vp_log("=== inject.dylib 已载入 pid=%d classes=%s main=%s ===",
           (int)getpid(), g_classes_dir, g_main_class);
    uint32_t count = _dyld_image_count();
    for (uint32_t index = 0; index < count; index++) {
        vp_rebind(_dyld_get_image_header(index), _dyld_get_image_vmaddr_slide(index));
    }
    _dyld_register_func_for_add_image(vp_image_added);
    /* 万一这个进程不创建 JVM（继承来的），也要能注入。 */
    vp_start_vm_watch();
}