#include <stdio.h>
#include <stdlib.h>

extern void wasker_main();

long linear_memory_base;
int linear_memory_block_num = 0;
const int LINEAR_MEMORY_BLOCK_SIZE = 64 * 1024;
const int LINEAR_MEMORY_BLOCK_NUM_MAX = 32;


//////////////////////////////////////////////
/// Wrapper of following WASI functions
/// - fd_write
/// - environ_get
/// - environ_sizes_get
/// - proc_exit
//////////////////////////////////////////////

typedef struct {
  int iov_base;
  int iov_len;
} IoVec;

typedef enum {
    SUCCESS,
    // Add other error types here
} WasiError;

WasiError fd_write(int fd, int buf_iovec_addr, int vec_len, int size_addr) {
    char* iovec_ptr = (char *)(linear_memory_base + buf_iovec_addr);
    IoVec* iovec = (IoVec*)iovec_ptr;

    int len = 0;
    for (int i = 0; i < vec_len; i++){
        char* buf_ptr = (char *)(linear_memory_base + iovec[i].iov_base);
        size_t buf_len = iovec[i].iov_len;
        for (int j = 0; j < buf_len; j++){
            printf("%c", buf_ptr[j]);
        }
        len += buf_len;
    }
    int* size_ptr = (int *)(linear_memory_base + size_addr);
    *size_ptr = len;
    return SUCCESS;
}

WasiError environ_get(int env_addrs, int env_buf_addr){
  // TODO: implement
  return SUCCESS;
}

WasiError environ_sizes_get(int env_count_addr, int env_buf_size_addr){
  // TODO: implement
  return SUCCESS;
}

void proc_exit(int code){
  exit(code);
}

//////////////////////////////////////////////
/// Provide linear memory with Wasm
//////////////////////////////////////////////

long memory_base(){
  // malloc 32 Block for linear memory
  char* memory = (char*)malloc(LINEAR_MEMORY_BLOCK_SIZE * LINEAR_MEMORY_BLOCK_NUM_MAX);
  linear_memory_base = (long)memory;
  return linear_memory_base;
}

long memory_grow(long num){
  int old = linear_memory_block_num;

  // check if there are enough memory
  if (LINEAR_MEMORY_BLOCK_NUM_MAX < linear_memory_block_num + num) {
    printf("memory_grow: failed to grow memory\n");
    return -1;
  }

  linear_memory_block_num += num;
  return old;
}

int main() {
  // Entrypoint of ELF generated by Wasker
  wasker_main();
  return 0;
}