/*
 * 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
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * 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.
 */

/*!
 * \file main.cc
 * \brief main entry point for host subprocess-based CRT
 */
#include <inttypes.h>
#include <time.h>
#include <tvm/runtime/c_runtime_api.h>
#include <tvm/runtime/crt/logging.h>
#include <tvm/runtime/crt/microtvm_rpc_server.h>
#include <tvm/runtime/crt/page_allocator.h>
#include <unistd.h>

#include <chrono>
#include <iostream>

#include "crt_config.h"

#ifdef TVM_HOST_USE_GRAPH_EXECUTOR_MODULE
#include <tvm/runtime/crt/graph_executor_module.h>
#endif

using namespace std::chrono;

extern "C" {

ssize_t MicroTVMWriteFunc(void* context, const uint8_t* data, size_t num_bytes) {
  ssize_t to_return = write(STDOUT_FILENO, data, num_bytes);
  fflush(stdout);
  fsync(STDOUT_FILENO);
  return to_return;
}

size_t TVMPlatformFormatMessage(char* out_buf, size_t out_buf_size_bytes, const char* fmt,
                                va_list args) {
  return vsnprintf(out_buf, out_buf_size_bytes, fmt, args);
}

void TVMPlatformAbort(tvm_crt_error_t error_code) {
  std::cerr << "TVMPlatformAbort: " << error_code << std::endl;
  throw "Aborted";
}

MemoryManagerInterface* memory_manager;

tvm_crt_error_t TVMPlatformMemoryAllocate(size_t num_bytes, DLDevice dev, void** out_ptr) {
  return memory_manager->Allocate(memory_manager, num_bytes, dev, out_ptr);
}

tvm_crt_error_t TVMPlatformMemoryFree(void* ptr, DLDevice dev) {
  return memory_manager->Free(memory_manager, ptr, dev);
}

steady_clock::time_point g_microtvm_start_time;
int g_microtvm_timer_running = 0;

tvm_crt_error_t TVMPlatformTimerStart() {
  if (g_microtvm_timer_running) {
    std::cerr << "timer already running" << std::endl;
    return kTvmErrorPlatformTimerBadState;
  }
  g_microtvm_start_time = std::chrono::steady_clock::now();
  g_microtvm_timer_running = 1;
  return kTvmErrorNoError;
}

tvm_crt_error_t TVMPlatformTimerStop(double* elapsed_time_seconds) {
  if (!g_microtvm_timer_running) {
    std::cerr << "timer not running" << std::endl;
    return kTvmErrorPlatformTimerBadState;
  }
  auto microtvm_stop_time = std::chrono::steady_clock::now();
  std::chrono::microseconds time_span = std::chrono::duration_cast<std::chrono::microseconds>(
      microtvm_stop_time - g_microtvm_start_time);
  *elapsed_time_seconds = static_cast<double>(time_span.count()) / 1e6;
  g_microtvm_timer_running = 0;
  return kTvmErrorNoError;
}

static_assert(RAND_MAX >= (1 << 8), "RAND_MAX is smaller than acceptable");
unsigned int random_seed = 0;
tvm_crt_error_t TVMPlatformGenerateRandom(uint8_t* buffer, size_t num_bytes) {
  if (random_seed == 0) {
    random_seed = (unsigned int)time(NULL);
  }
  for (size_t i = 0; i < num_bytes; ++i) {
    int random = rand_r(&random_seed);
    buffer[i] = (uint8_t)random;
  }

  return kTvmErrorNoError;
}
}

uint8_t memory[2048 * 1024];

static char** g_argv = NULL;

int testonly_reset_server(TVMValue* args, int* type_codes, int num_args, TVMValue* out_ret_value,
                          int* out_ret_tcode, void* resource_handle) {
  execvp(g_argv[0], g_argv);
  perror("microTVM runtime: error restarting");
  return -1;
}

int main(int argc, char** argv) {
  g_argv = argv;
  int status =
      PageMemoryManagerCreate(&memory_manager, memory, sizeof(memory), 8 /* page_size_log2 */);
  if (status != 0) {
    fprintf(stderr, "error initiailizing memory manager\n");
    return 2;
  }

  microtvm_rpc_server_t rpc_server = MicroTVMRpcServerInit(&MicroTVMWriteFunc, nullptr);

#ifdef TVM_HOST_USE_GRAPH_EXECUTOR_MODULE
  CHECK_EQ(TVMGraphExecutorModule_Register(), kTvmErrorNoError,
           "failed to register GraphExecutor TVMModule");
#endif

  int error = TVMFuncRegisterGlobal("tvm.testing.reset_server",
                                    (TVMFunctionHandle)&testonly_reset_server, 0);
  if (error) {
    fprintf(
        stderr,
        "microTVM runtime: internal error (error#: %x) registering global packedfunc; exiting\n",
        error);
    return 2;
  }

  setbuf(stdin, NULL);
  setbuf(stdout, NULL);

  for (;;) {
    uint8_t c;
    int ret_code = read(STDIN_FILENO, &c, 1);
    if (ret_code < 0) {
      perror("microTVM runtime: read failed");
      return 2;
    } else if (ret_code == 0) {
      fprintf(stderr, "microTVM runtime: 0-length read, exiting!\n");
      return 2;
    }
    uint8_t* cursor = &c;
    size_t bytes_to_process = 1;
    while (bytes_to_process > 0) {
      tvm_crt_error_t err = MicroTVMRpcServerLoop(rpc_server, &cursor, &bytes_to_process);
      if (err == kTvmErrorPlatformShutdown) {
        break;
      } else if (err != kTvmErrorNoError) {
        char buf[1024];
        snprintf(buf, sizeof(buf), "microTVM runtime: MicroTVMRpcServerLoop error: %08x", err);
        perror(buf);
        return 2;
      }
    }
  }
  return 0;
}