#include "git-compat-util.h"

#include "config.h"

#include "editor.h"

#include "pager.h"

#include "run-command.h"

#include "sigchain.h"

#include "alias.h"

int pager_use_color = 1;

#ifndef DEFAULT_PAGER

#define DEFAULT_PAGER "less"

#endif

static struct child_process pager_process;

static char *pager_program;

static int old_fd1 = -1, old_fd2 = -1;

/* Is the value coming back from term_columns() just a guess? */

static int term_columns_guessed;

static void close_pager_fds(void)

{

  /* signal EOF to pager */

  close(1);

  if (old_fd2 != -1)

    close(2);

}

static void finish_pager(void)

{

  fflush(stdout);

  fflush(stderr);

  close_pager_fds();

  finish_command(&pager_process);

}

static void wait_for_pager_atexit(void)

{

  if (old_fd1 == -1)

    return;

  finish_pager();

}

void wait_for_pager(void)

{

  if (old_fd1 == -1)

    return;

  finish_pager();

  sigchain_pop_common();

  unsetenv("GIT_PAGER_IN_USE");

  dup2(old_fd1, 1);

  close(old_fd1);

  old_fd1 = -1;

  if (old_fd2 != -1) {

    dup2(old_fd2, 2);

    close(old_fd2);

    old_fd2 = -1;

  }

}

static void wait_for_pager_signal(int signo)

{

  if (old_fd1 == -1)

    return;

  close_pager_fds();

  finish_command_in_signal(&pager_process);

  sigchain_pop(signo);

  raise(signo);

}

static int core_pager_config(const char *var, const char *value,

           const struct config_context *ctx UNUSED,

           void *data UNUSED)

{

  if (!strcmp(var, "core.pager"))

    return git_config_string(&pager_program, var, value);

  return 0;

}

const char *git_pager(int stdout_is_tty)

{

  const char *pager;

  if (!stdout_is_tty)

    return NULL;

  pager = getenv("GIT_PAGER");

  if (!pager) {

    if (!pager_program)

      read_early_config(core_pager_config, NULL);

    pager = pager_program;

  }

  if (!pager)

    pager = getenv("PAGER");

  if (!pager)

    pager = DEFAULT_PAGER;

  if (!*pager || !strcmp(pager, "cat"))

    pager = NULL;

  return pager;

}

static void setup_pager_env(struct strvec *env)

{

  const char **argv;

  int i;

  char *pager_env = xstrdup(PAGER_ENV);

  int n = split_cmdline(pager_env, &argv);

  if (n < 0)

    die("malformed build-time PAGER_ENV: %s",

      split_cmdline_strerror(n));

  for (i = 0; i < n; i++) {

    char *cp = strchr(argv[i], '=');

    if (!cp)

      die("malformed build-time PAGER_ENV");

    *cp = '\0';

    if (!getenv(argv[i])) {

      *cp = '=';

      strvec_push(env, argv[i]);

    }

  }

  free(pager_env);

  free(argv);

}

void prepare_pager_args(struct child_process *pager_process, const char *pager)

{

  strvec_push(&pager_process->args, pager);

  pager_process->use_shell = 1;

  setup_pager_env(&pager_process->env);

  pager_process->trace2_child_class = "pager";

}

void setup_pager(void)

{

  static int once = 0;

  const char *pager = git_pager(isatty(1));

  if (!pager)

    return;

  /*

   * After we redirect standard output, we won't be able to use an ioctl

   * to get the terminal size. Let's grab it now, and then set $COLUMNS

   * to communicate it to any sub-processes.

   */

  {

    char buf[64];

    xsnprintf(buf, sizeof(buf), "%d", term_columns());

    if (!term_columns_guessed)

      setenv("COLUMNS", buf, 0);

  }

  setenv("GIT_PAGER_IN_USE", "true", 1);

  child_process_init(&pager_process);

  /* spawn the pager */

  prepare_pager_args(&pager_process, pager);

  pager_process.in = -1;

  strvec_push(&pager_process.env, "GIT_PAGER_IN_USE");

  if (start_command(&pager_process))

    die("unable to execute pager '%s'", pager);

  /* original process continues, but writes to the pipe */

  old_fd1 = dup(1);

  dup2(pager_process.in, 1);

  if (isatty(2)) {

    old_fd2 = dup(2);

    dup2(pager_process.in, 2);

  }

  close(pager_process.in);

  sigchain_push_common(wait_for_pager_signal);

  if (!once) {

    once++;

    atexit(wait_for_pager_atexit);

  }

}

int pager_in_use(void)

{

  return git_env_bool("GIT_PAGER_IN_USE", 0);

}

/*

 * Return cached value (if set) or $COLUMNS environment variable (if

 * set and positive) or ioctl(1, TIOCGWINSZ).ws_col (if positive),

 * and default to 80 if all else fails.

 */

int term_columns(void)

{

  static int term_columns_at_startup;

  char *col_string;

  int n_cols;

  if (term_columns_at_startup)

    return term_columns_at_startup;

  term_columns_at_startup = 80;

  term_columns_guessed = 1;

  col_string = getenv("COLUMNS");

  if (col_string && (n_cols = atoi(col_string)) > 0) {

    term_columns_at_startup = n_cols;

    term_columns_guessed = 0;

  }

#ifdef TIOCGWINSZ

  else {

    struct winsize ws;

    if (!ioctl(1, TIOCGWINSZ, &ws) && ws.ws_col) {

      term_columns_at_startup = ws.ws_col;

      term_columns_guessed = 0;

    }

  }

#endif

  return term_columns_at_startup;

}

/*

 * Clear the entire line, leave cursor in first column.

 */

void term_clear_line(void)

{

  if (!isatty(2))

    return;

  if (is_terminal_dumb())

    /*

     * Fall back to print a terminal width worth of space

     * characters (hoping that the terminal is still as wide

     * as it was upon the first call to term_columns()).

     */

    fprintf(stderr, "\r%*s\r", term_columns(), "");

  else

    /*

     * On non-dumb terminals use an escape sequence to clear

     * the whole line, no matter how wide the terminal.

     */

    fputs("\r\033[K", stderr);

}

/*

 * How many columns do we need to show this number in decimal?

 */

int decimal_width(uintmax_t number)

{

  int width;

  for (width = 1; number >= 10; width++)

    number /= 10;

  return width;

}

struct pager_command_config_data {

  const char *cmd;

  int want;

  char *value;

};

static int pager_command_config(const char *var, const char *value,

        const struct config_context *ctx UNUSED,

        void *vdata)

{

  struct pager_command_config_data *data = vdata;

  const char *cmd;

  if (skip_prefix(var, "pager.", &cmd) && !strcmp(cmd, data->cmd)) {

    int b = git_parse_maybe_bool(value);

    if (b >= 0)

      data->want = b;

    else {

      data->want = 1;

      data->value = xstrdup(value);

    }

  }

  return 0;

}

/* returns 0 for "no pager", 1 for "use pager", and -1 for "not specified" */

int check_pager_config(const char *cmd)

{

  struct pager_command_config_data data;

  data.cmd = cmd;

  data.want = -1;

  data.value = NULL;

  read_early_config(pager_command_config, &data);

  if (data.value)

    pager_program = data.value;

  return data.want;

}