/*
 * pgdisplay, a PostgreSQL app to display a table
 * in an informative way.
 *
 * This software is released under the PostgreSQL Licence.
 *
 * Guillaume Lelarge, guillaume@lelarge.info, 2015-2024.
 *
 * pgstat/pgdisplay.c
 */


/*
 * System headers
 */
#include <err.h>
#include <sys/signal.h>

/*
 * PostgreSQL headers
 */
#include "postgres_fe.h"
#include "common/logging.h"
#include "fe_utils/connect_utils.h"

/*
 * Defines
 */
#define PGDISPLAY_VERSION "0.0.1"
#define  PGSTAT_DEFAULT_STRING_SIZE 1024

#define couleur(param) printf("\033[48;2;255;%d;%dm",param,param)
#define nocouleur() printf("\033[0m")

/* these are the options structure for command line parameters */
struct options
{
  /* misc */
  bool verbose;
  char *table;
  int  groups;
  int  blocksize;

  /* connection parameters */
  char *dbname;
  char *hostname;
  char *port;
  char *username;

  /* version number */
  int  major;
  int  minor;
};

/*
 * Global variables
 */
PGconn         *conn;
struct options *opts;
extern char    *optarg;

/*
 * Function prototypes
 */
static void  help(const char *progname);
void         get_opts(int, char **);
#ifndef FE_MEMUTILS_H
void         *pg_malloc(size_t size);
char         *pg_strdup(const char *in);
#endif
void         display_fsm(char *table);
void         fetch_version(void);
void         fetch_blocksize(void);
bool         backend_minimum_version(int major, int minor);
void         allocate_struct(void);
static void  quit_properly(SIGNAL_ARGS);

/*
 * Print help message
 */
static void
help(const char *progname)
{
  printf("%s displays table in an informative way.\n\n"
       "Usage:\n"
       "  %s [OPTIONS] [delay [count]]\n"
       "\nGeneral options:\n"
       "  -G GROUPS      # of groups of blocks\n"
       "  -t TABLE       table to display\n"
       "  -v             verbose\n"
       "  -?|--help      show this help, then exit\n"
       "  -V|--version   output version information, then exit\n"
       "\nConnection options:\n"
       "  -h HOSTNAME    database server host or socket directory\n"
       "  -p PORT        database server port number\n"
       "  -U USER        connect as specified database user\n"
       "  -d DBNAME      database to connect to\n"
       "Report bugs to <guillaume@lelarge.info>.\n",
       progname, progname);
}

/*
 * Parse command line options and check for some usage errors
 */
void
get_opts(int argc, char **argv)
{
  int        c;
  const char *progname;

  progname = get_progname(argv[0]);

  /* set the defaults */
  opts->verbose = false;
  opts->groups = 20;
  opts->blocksize = 0;
  opts->table = NULL;
  opts->dbname = NULL;
  opts->hostname = NULL;
  opts->port = NULL;
  opts->username = NULL;

  if (argc > 1)
  {
    if (strcmp(argv[1], "--help") == 0 || strcmp(argv[1], "-?") == 0)
    {
      help(progname);
      exit(0);
    }
    if (strcmp(argv[1], "--version") == 0 || strcmp(argv[1], "-V") == 0)
    {
      puts("pgdisplay " PGDISPLAY_VERSION " (compiled with PostgreSQL " PG_VERSION ")");
      exit(0);
    }
  }

  /* get opts */
  while ((c = getopt(argc, argv, "h:p:U:d:t:G:v")) != -1)
  {
    switch (c)
    {
        /* specify the # of groups */
      case 'G':
        opts->groups = atoi(optarg);
        break;

        /* specify the table */
      case 't':
        opts->table = pg_strdup(optarg);
        break;

        /* don't show headers */
      case 'v':
        opts->verbose = true;
        break;

        /* specify the database */
      case 'd':
        opts->dbname = pg_strdup(optarg);
        break;

        /* host to connect to */
      case 'h':
        opts->hostname = pg_strdup(optarg);
        break;

        /* port to connect to on remote host */
      case 'p':
        opts->port = pg_strdup(optarg);
        break;

        /* username */
      case 'U':
        opts->username = pg_strdup(optarg);
        break;

      default:
        errx(1, "Try \"%s --help\" for more information.\n", progname);
        exit(EXIT_FAILURE);
    }
  }

  if (opts->table == NULL)
  {
    pg_log_error("missing table name\n");
    exit(EXIT_FAILURE);
  }

  if (opts->dbname == NULL)
  {
    /*
     * We want to use dbname for possible error reports later,
     * and in case someone has set and is using PGDATABASE
     * in its environment preserve that name for later usage
     */
    if (!getenv("PGDATABASE"))
      opts->dbname = "postgres";
    else
      opts->dbname = getenv("PGDATABASE");
  }
}

#ifndef FE_MEMUTILS_H
/*
 * "Safe" wrapper around malloc().
 */
void *
pg_malloc(size_t size)
{
  void *tmp;

  /* Avoid unportable behavior of malloc(0) */
  if (size == 0)
    size = 1;
  tmp = malloc(size);
  if (!tmp)
  {
    pg_log_error("out of memory\n");
    exit(EXIT_FAILURE);
  }
  return tmp;
}

/*
 * "Safe" wrapper around strdup().
 */
char *
pg_strdup(const char *in)
{
  char *tmp;

  if (!in)
  {
    pg_log_error("cannot duplicate null pointer (internal error)\n");
    exit(EXIT_FAILURE);
  }
  tmp = strdup(in);
  if (!tmp)
  {
    pg_log_error("out of memory\n");
    exit(EXIT_FAILURE);
  }
  return tmp;
}
#endif

/*
 * Dump all archiver stats.
 */
void
display_fsm(char *table)
{
  char     sql[PGSTAT_DEFAULT_STRING_SIZE];
  PGresult *res;
  int      nrows;
  int      row;
  int      color;
  int      totalspace, freespace;
  int      groupby, blocksize;
  int      n;

  blocksize = 8192;

  /* grab the stats (this is the only stats on one line) */
  /*
  snprintf(sql, sizeof(sql),
       "with fsm as (select blkno/443 as blockrange, sum(avail) as available, 8192*443 as total from pg_freespace('%s') group by 1)"
       "select blockrange, available, total, 100*available/total as ratio, 180*available/total as color from fsm order by 1",
       table);
  */
  snprintf(sql, sizeof(sql),
    "select avail from pg_freespace('%s') order by blkno",
    table);

  /* make the call */
  res = PQexec(conn, sql);

  /* check and deal with errors */
  if (!res || PQresultStatus(res) > 2)
  {
    warnx("pgdisplay: query failed: %s", PQerrorMessage(conn));
    PQclear(res);
    PQfinish(conn);
    errx(1, "pgdisplay: query was: %s", sql);
  }

  /* get the number of fields */
  nrows = PQntuples(res);

  /* initialize some vars */
  totalspace = nrows*blocksize;
  if (nrows <= opts->groups)
    groupby = 1;
  else
    groupby = nrows/opts->groups;
  freespace = 0;
  n = 0;

  printf("Pages #:     %d\n", nrows);
  printf("Table size:  %d\n", totalspace);
  printf("... group of %d\n", groupby);
  printf("\n\n");

  /* for each row, dump the information */
  for (row = 0; row < nrows; row++)
  {
    /* getting new values */
    freespace += atol(PQgetvalue(res, row, 0));

    if (++n >= groupby)
    {
      //printf("Free space [%d] : %d (on %d)\n", n, freespace, groupby*blocksize);
      /* printing the diff...
       * note that the first line will be the current value, rather than the diff */
      color = 180*freespace/(8192*groupby);
      if (color<0)
        color = 0;
      couleur(color);
      printf(" ");
      nocouleur();

      freespace = 0;
      n = 0;
    }
  }

  printf("\n\n");
  /* cleanup */
  PQclear(res);
}

/*
 * Fetch block size.
 */
void
fetch_blocksize()
{
  char     sql[PGSTAT_DEFAULT_STRING_SIZE];
  PGresult *res;

  /* get the cluster version */
  snprintf(sql, sizeof(sql), "SELECT current_setting('block_size')");

  /* make the call */
  res = PQexec(conn, sql);

  /* check and deal with errors */
  if (!res || PQresultStatus(res) > 2)
  {
    warnx("pgdisplay: query failed: %s", PQerrorMessage(conn));
    PQclear(res);
    PQfinish(conn);
    errx(1, "pgdisplay: query was: %s", sql);
  }

  /* get the only row, and parse it to get major and minor numbers */
  opts->blocksize = atoi(PQgetvalue(res, 0, 0));

  /* print version */
  if (opts->verbose)
    printf("Detected block size: %d\n", opts->blocksize);

  /* cleanup */
  PQclear(res);
}

/*
 * Fetch PostgreSQL major and minor numbers
 */
void
fetch_version()
{
  char     sql[PGSTAT_DEFAULT_STRING_SIZE];
  PGresult *res;

  /* get the cluster version */
  snprintf(sql, sizeof(sql), "SELECT version()");

  /* make the call */
  res = PQexec(conn, sql);

  /* check and deal with errors */
  if (!res || PQresultStatus(res) > 2)
  {
    warnx("pgdisplay: query failed: %s", PQerrorMessage(conn));
    PQclear(res);
    PQfinish(conn);
    errx(1, "pgdisplay: query was: %s", sql);
  }

  /* get the only row, and parse it to get major and minor numbers */
  sscanf(PQgetvalue(res, 0, 0), "%*s %d.%d", &(opts->major), &(opts->minor));

  /* print version */
  if (opts->verbose)
    printf("Detected release: %d.%d\n", opts->major, opts->minor);

  /* cleanup */
  PQclear(res);
}

/*
 * Compare given major and minor numbers to the one of the connected server
 */
bool
backend_minimum_version(int major, int minor)
{
  return opts->major > major || (opts->major == major && opts->minor >= minor);
}

/*
 * Close the PostgreSQL connection, and quit
 */
static void
quit_properly(SIGNAL_ARGS)
{
  PQfinish(conn);
  exit(EXIT_FAILURE);
}

/*
 * Main function
 */
int
main(int argc, char **argv)
{
  const char *progname;
  ConnParams cparams;

  /*
   * If the user stops the program (control-Z) and then resumes it,
   * print out the header again.
   */
  pqsignal(SIGINT, quit_properly);

  /* Allocate the options struct */
  opts = (struct options *) pg_malloc(sizeof(struct options));

  /* Parse the options */
  get_opts(argc, argv);

  /* Initialize the logging interface */
  pg_logging_init(argv[0]);

  /* Get the program name */
  progname = get_progname(argv[0]);

  /* Set the connection struct */
  cparams.pghost = opts->hostname;
  cparams.pgport = opts->port;
  cparams.pguser = opts->username;
  cparams.dbname = opts->dbname;
  cparams.prompt_password = TRI_DEFAULT;
  cparams.override_dbname = NULL;

  /* Connect to the database */
  conn = connectDatabase(&cparams, progname, false, false, false);

  // check last vacuum timestamp
  // fetch blocks count

  fetch_blocksize();

  display_fsm(opts->table);

  PQfinish(conn);
  return 0;
}