#include "common.h"
#include "config.h"
#include "log.h"

f2b_config_param_t *
f2b_config_parse_kv_pair(const char *src) {
  f2b_config_param_t *param = NULL;
  char line[CONFIG_LINE_MAX] = "";
  char *p, *key, *value;
  size_t len;

  strncpy(line, src, sizeof(line));
  line[CONFIG_LINE_MAX] = '\0';

  /* strip spaces before key */
  key = line;
  while (isblank(*key))
    key++;

  if ((value = strchr(key, '=')) == NULL)
    return NULL;

  /* strip spaces after key */
  p = value - 1;
  while (p > line && isblank(*p))
    p--;
  p++, *p = '\0';

  value++; /* move to next char after '=' */
  while (isblank(*value))
    value++;

  /* strip trailing comment */
  if ((p = strstr(value,  " #")) != NULL) *p = '\0';
  if ((p = strstr(value, "\t#")) != NULL) *p = '\0';
  if ((p = strstr(value,  " ;")) != NULL) *p = '\0';
  if ((p = strstr(value, "\t;")) != NULL) *p = '\0';

  /* strip trailing spaces */
  p = value + strlen(value);
  if (p > value)
    p--; /* step back at char before '\0' */
  while (p > value && isspace(*p))
    p--;
  p++, *p = '\0';

  len = strlen(key);
  if (len < 1 || len > CONFIG_KEY_MAX)
    return NULL;

  len = strlen(value);
  if (len < 1 || len > CONFIG_VAL_MAX)
    return NULL;

  if ((param = calloc(1, sizeof(f2b_config_param_t))) != NULL) {
    strncpy(param->name,  key,   sizeof(param->name));
    strncpy(param->value, value, sizeof(param->value));
    param->name[CONFIG_KEY_MAX] = '\0';
    param->name[CONFIG_VAL_MAX] = '\0';
    return param;
  }

  return NULL;
}

f2b_config_section_t *
f2b_config_parse_section(const char *src) {
  f2b_config_section_t *section = NULL;
  char line[CONFIG_LINE_MAX] = "";
  char *name, *end;

  strncpy(line, src, sizeof(line));
  line[CONFIG_LINE_MAX] = '\0';

  if ((end = strchr(line, ']')) == NULL)
    return NULL;
  *end = '\0';

  if ((section = calloc(1, sizeof(f2b_config_section_t))) == NULL)
    return NULL;

  name = "[defaults]";
  if (strncmp(line, name, strlen(name)) == 0) {
    section->type = t_defaults;
    return section;
  }

  name = "[backend:";
  if (strncmp(line, name, strlen(name)) == 0) {
    section->type = t_backend;
    strncpy(section->name, line + strlen(name), sizeof(section->name));
    return section;
  }

  name = "[jail:";
  if (strncmp(line, name, strlen(name)) == 0) {
    section->type = t_jail;
    strncpy(section->name, line + strlen(name), sizeof(section->name));
    return section;
  }

  free(section);
  return NULL;
}

f2b_config_section_t *
f2b_config_find_section(f2b_config_section_t *section, f2b_section_type type, const char *name) {
  for (; section != NULL; section = section->next) {
    if (section->type == type && strcmp(section->name, name) == 0)
      return section;
  }

  return NULL;
}

f2b_config_param_t *
f2b_config_find_param(f2b_config_param_t *param, const char *name) {
  for (; param != NULL; param = param->next) {
    if (strcmp(name, param->name) == 0)
      return param;
  }

  return NULL;
}

f2b_config_section_t *
f2b_config_append_param(f2b_config_section_t *section, f2b_config_param_t *param) {
  if (section->param) {
    section->last->next = param;
    section->last = section->last->next;
  } else {
    section->param = param;
    section->last  = param;
  }
  return section;
}

f2b_config_section_t *
f2b_config_load(const char *path) {
  f2b_config_section_t *config  = NULL; /* always points to current section */
  f2b_config_section_t *section = NULL; /* temp pointer */
  f2b_config_param_t   *param   = NULL; /* temp pointer */
  FILE *f = NULL; /* config file fd */
  char *p; /* temp pointer */
  char line[CONFIG_LINE_MAX] = ""; /* last read line */
  bool skip_section = false; /* if set - skip parameters unless next section */
  size_t linenum = 0; /* current line number in config */

  if ((f = fopen(path, "r")) == NULL) {
    f2b_log_msg(log_error, "can't open config file '%s': %s", path, strerror(errno));
    return NULL;
  }

  if ((config = calloc(1, sizeof(f2b_config_section_t))) == NULL)
    return NULL;
  config->type = t_main;

  while (1) {
    p = fgets(line, sizeof(line), f);
    if (!p && (feof(f) || ferror(f)))
      break;
    while (isblank(*p))
      p++;
    linenum++;
    switch(*p) {
      case '\0':
      case '\r':
      case '\n':
        /* empty line */
        break;
      case ';':
      case '#':
        /* comment line */
        break;
      case '[':
        /* section header */
        section = f2b_config_parse_section(p);
        if (section) {
          skip_section = false;
          section->next = config;
          config = section;
        } else {
          skip_section = true;
          f2b_log_msg(log_error, "unknown section at line %d: %s", linenum, p);
        }
        break;
      default:
        if (skip_section) {
          f2b_log_msg(log_warn, "skipping line in unknown section: %s", p);
          continue;
        }
        /* key/value pair */
        param = f2b_config_parse_kv_pair(p);
        if (param) {
          f2b_config_append_param(config, param);
        } else {
          f2b_log_msg(log_error, "can't parse key/value at line %d: %s", linenum, p);
        }
        break;
    } /* switch */
  } /* while */
  fclose(f);

  return config;
}

void
f2b_config_free(f2b_config_section_t *config) {
  f2b_config_section_t *next_section = NULL;
  f2b_config_param_t   *next_param   = NULL;

  for (; config != NULL; config = next_section) {
    next_section = config->next;
    for (; config->param != NULL; config->param = next_param) {
      next_param = config->param->next;
      FREE(config->param);
    }
    FREE(config);
  }
}