#include <fcntl.h>
#include <stdbool.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>

struct Connection_t {
  int file_descriptor;
};
typedef struct Connection_t Connection;

Connection* open_connection(char* filename) {
  int fd = open(filename,
                O_RDWR |      // Read/Write mode
                    O_CREAT,  // Create file if it does not exist
                S_IWUSR |     // Create file with user write permission
                    S_IRUSR   // Create file with user read permission
                );

  if (fd == -1) {
    printf("Unable to open file '%s'\n", filename);
    exit(EXIT_FAILURE);
  }

  Connection* connection = malloc(sizeof(Connection));
  connection->file_descriptor = fd;

  return connection;
}

char* get_db_filename(int argc, char* argv[]) {
  if (argc < 2) {
    printf("Must supply a filename for the database.\n");
    exit(EXIT_FAILURE);
  }
  return argv[1];
}

struct InputBuffer_t {
  char* buffer;
  size_t buffer_length;
  ssize_t input_length;
};
typedef struct InputBuffer_t InputBuffer;

InputBuffer* new_input_buffer() {
  InputBuffer* input_buffer = malloc(sizeof(InputBuffer));
  input_buffer->buffer = NULL;
  input_buffer->buffer_length = 0;
  input_buffer->input_length = 0;

  return input_buffer;
}

void print_prompt() { printf("db > "); }

void read_input(InputBuffer* input_buffer) {
  ssize_t bytes_read =
      getline(&(input_buffer->buffer), &(input_buffer->buffer_length), stdin);

  if (bytes_read <= 0) {
    printf("Error reading input\n");
    exit(EXIT_FAILURE);
  }

  // Ignore trailing newline
  input_buffer->input_length = bytes_read - 1;
  input_buffer->buffer[bytes_read - 1] = 0;
}

int main(int argc, char* argv[]) {
  char* db_filename = get_db_filename(argc, argv);
  Connection* connection = open_connection(db_filename);

  InputBuffer* input_buffer = new_input_buffer();
  while (true) {
    print_prompt();
    read_input(input_buffer);

    if (strcmp(input_buffer->buffer, ".exit") == 0) {
      exit(EXIT_SUCCESS);
    } else {
      printf("Unrecognized command '%s'.\n", input_buffer->buffer);
    }
  }
}