/*
 * Copyright (c) 2019, 2024, Oracle and/or its affiliates. All rights reserved.
 * Copyright (c) 2019, Google and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */

#include <assert.h>
#include <dlfcn.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include "jvmti.h"

static jvmtiEnv* jvmti;

template <class T>
class JvmtiDeallocator {
 public:
  JvmtiDeallocator() {
    elem_ = nullptr;
  }

  ~JvmtiDeallocator() {
    jvmti->Deallocate(reinterpret_cast<unsigned char*>(elem_));
  }

  T* get_addr() {
    return &elem_;
  }

  T get() {
    return elem_;
  }

 private:
  T elem_;
};

static void GetJMethodIDs(jclass klass) {
  jint method_count = 0;
  JvmtiDeallocator<jmethodID*> methods;
  jvmtiError err = jvmti->GetClassMethods(klass, &method_count, methods.get_addr());

  // If ever the GetClassMethods fails, just ignore it, it was worth a try.
  if (err != JVMTI_ERROR_NONE) {
    fprintf(stderr, "GetJMethodIDs: Error in GetClassMethods: %d\n", err);
  }
}

// AsyncGetCallTrace needs class loading events to be turned on!
static void JNICALL OnClassLoad(jvmtiEnv *jvmti, JNIEnv *jni_env,
                                jthread thread, jclass klass) {
}

static void JNICALL OnClassPrepare(jvmtiEnv *jvmti, JNIEnv *jni_env,
                                   jthread thread, jclass klass) {
  // We need to do this to "prime the pump" and get jmethodIDs primed.
  GetJMethodIDs(klass);
}

static void JNICALL OnVMInit(jvmtiEnv *jvmti, JNIEnv *jni_env, jthread thread) {
  jint class_count = 0;

  // Get any previously loaded classes that won't have gone through the
  // OnClassPrepare callback to prime the jmethods for AsyncGetCallTrace.
  JvmtiDeallocator<jclass*> classes;
  jvmtiError err = jvmti->GetLoadedClasses(&class_count, classes.get_addr());
  if (err != JVMTI_ERROR_NONE) {
    fprintf(stderr, "OnVMInit: Error in GetLoadedClasses: %d\n", err);
    return;
  }

  // Prime any class already loaded and try to get the jmethodIDs set up.
  jclass *classList = classes.get();
  for (int i = 0; i < class_count; ++i) {
    GetJMethodIDs(classList[i]);
  }
}

extern "C" {

static
jint Agent_Initialize(JavaVM *jvm, char *options, void *reserved) {
  jint res = jvm->GetEnv((void **) &jvmti, JVMTI_VERSION);
  if (res != JNI_OK || jvmti == nullptr) {
    fprintf(stderr, "Error: wrong result of a valid call to GetEnv!\n");
    return JNI_ERR;
  }

  jvmtiError err;
  jvmtiCapabilities caps;
  memset(&caps, 0, sizeof(caps));
  caps.can_get_line_numbers = 1;
  caps.can_get_source_file_name = 1;

  err = jvmti->AddCapabilities(&caps);
  if (err != JVMTI_ERROR_NONE) {
    fprintf(stderr, "AgentInitialize: Error in AddCapabilities: %d\n", err);
    return JNI_ERR;
  }

  jvmtiEventCallbacks callbacks;
  memset(&callbacks, 0, sizeof(callbacks));
  callbacks.ClassLoad = &OnClassLoad;
  callbacks.VMInit = &OnVMInit;
  callbacks.ClassPrepare = &OnClassPrepare;

  err = jvmti->SetEventCallbacks(&callbacks, sizeof(jvmtiEventCallbacks));
  if (err != JVMTI_ERROR_NONE) {
    fprintf(stderr, "AgentInitialize: Error in SetEventCallbacks: %d\n", err);
    return JNI_ERR;
  }

  err = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_CLASS_LOAD, nullptr);
  if (err != JVMTI_ERROR_NONE) {
    fprintf(stderr, "AgentInitialize: Error in SetEventNotificationMode for CLASS_LOAD: %d\n", err);
    return JNI_ERR;
  }

  err = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_CLASS_PREPARE, nullptr);
  if (err != JVMTI_ERROR_NONE) {
    fprintf(stderr,
            "AgentInitialize: Error in SetEventNotificationMode for CLASS_PREPARE: %d\n",
            err);
    return JNI_ERR;
  }

  err = jvmti->SetEventNotificationMode(JVMTI_ENABLE, JVMTI_EVENT_VM_INIT, nullptr);
  if (err != JVMTI_ERROR_NONE) {
    fprintf(
        stderr, "AgentInitialize: Error in SetEventNotificationMode for VM_INIT: %d\n",
        err);
    return JNI_ERR;
  }

  return JNI_OK;
}

JNIEXPORT
jint JNICALL Agent_OnLoad(JavaVM *jvm, char *options, void *reserved) {
  return Agent_Initialize(jvm, options, reserved);
}

JNIEXPORT
jint JNICALL Agent_OnAttach(JavaVM *jvm, char *options, void *reserved) {
  return Agent_Initialize(jvm, options, reserved);
}

JNIEXPORT
jint JNICALL JNI_OnLoad(JavaVM *jvm, void *reserved) {
  return JNI_VERSION_1_8;
}

// A copy of the ASGCT data structures.
typedef struct {
    jint lineno;                      // line number in the source file
    jmethodID method_id;              // method executed in this frame
} ASGCT_CallFrame;

typedef struct {
    JNIEnv *env_id;                   // Env where trace was recorded
    jint num_frames;                  // number of frames in this trace
    ASGCT_CallFrame *frames;          // frames
} ASGCT_CallTrace;

typedef void (*ASGCTType)(ASGCT_CallTrace *, jint, void *);

JNIEXPORT jboolean JNICALL
Java_MyPackage_ASGCTBaseTest_checkAsyncGetCallTraceCall(JNIEnv* env, jclass cls) {
  ASGCTType agct = reinterpret_cast<ASGCTType>(dlsym(RTLD_DEFAULT, "AsyncGetCallTrace"));

  const int MAX_DEPTH = 16;
  ASGCT_CallTrace trace;
  ASGCT_CallFrame frames[MAX_DEPTH];
  trace.frames = frames;
  trace.env_id = env;
  trace.num_frames = 0;

  if (agct == nullptr) {
    fprintf(stderr, "AsyncGetCallTrace not found.\n");
    return false;
  }

  agct(&trace, MAX_DEPTH, nullptr);

  // For now, just check that the first frame is (-3, checkAsyncGetCallTraceCall).
  if (trace.num_frames <= 0) {
    fprintf(stderr, "The num_frames must be positive: %d\n", trace.num_frames);
    return false;
  }

  // AsyncGetCallTrace returns -3 as line number for a native frame.
  if (trace.frames[0].lineno != -3) {
    fprintf(stderr, "lineno is not -3 as expected: %d\n", trace.frames[0].lineno);
    return false;
  }

  JvmtiDeallocator<char*> name;
  if (trace.frames[0].method_id == nullptr) {
    fprintf(stderr, "First frame method_id is null\n");
    return false;
  }

  jvmtiError err = jvmti->GetMethodName(trace.frames[0].method_id, name.get_addr(), nullptr, nullptr);
  if (err != JVMTI_ERROR_NONE) {
    fprintf(stderr, "checkAsyncGetCallTrace: Error in GetMethodName: %d\n", err);
    return false;
  }

  if (name.get() == nullptr) {
    fprintf(stderr, "Name is null\n");
    return false;
  }

  if (strcmp(name.get(), "checkAsyncGetCallTraceCall") != 0) {
    fprintf(stderr, "Name is not checkAsyncGetCallTraceCall: %s\n", name.get());
    return false;
  }

  // AsyncGetCallTrace and GetStackTrace should return comparable frames
  // so we obtain the frames using GetStackTrace and compare them.

  jthread thread;
  jvmti->GetCurrentThread(&thread);
  jvmtiFrameInfo gstFrames[MAX_DEPTH];
  jint gstCount = 0;

  jvmti->GetStackTrace(thread, 0, MAX_DEPTH, gstFrames, &gstCount);

  if (gstCount != trace.num_frames) {
    fprintf(stderr, "GetStackTrace and AsyncGetCallTrace return different number of frames: %d vs %d)", gstCount, trace.num_frames);
    return false;
  }

  for (int i = 0; i < trace.num_frames; ++i) {
    if (trace.frames[i].lineno == -3) {
      if (gstFrames[i].location != -1) {
        fprintf(stderr, "%d: ASGCT found native frame but GST did not\n", i);
        return false;
      }
    } else {
      if (gstFrames[i].method != trace.frames[i].method_id) {
        fprintf(stderr, "%d: method_id mismatch: %p vs %p\n", i, gstFrames[i].method, trace.frames[i].method_id);
        return false;
      }
    }
  }
  return true;
}

}