#include "monitor_proc.h"

#include <linux/kernel.h>
#include <linux/proc_fs.h>
#include <linux/types.h>
#include <linux/uaccess.h>

char *proc_dir = "variable_monitor";
int def_interval_ns = DEFAULT_INTERVAL_NS;
int dump_reset_sec = DEFAULT_DUMP_RESET_SEC;

static ssize_t read_proc(struct file *file, char __user *buf, size_t count,
                         loff_t *offset, int *var) {
  char temp_buf[32];
  size_t len = sprintf(temp_buf, "%d\n", *var);

  return simple_read_from_buffer(buf, count, offset, temp_buf, len);
}

static ssize_t write_proc(struct file *file, const char __user *buf,
                          size_t count, loff_t *offset, int *var) {
  char temp_buf[32];
  if (count > sizeof(temp_buf) - 1)
    return -EINVAL;

  if (copy_from_user(temp_buf, buf, count))
    return -EFAULT;

  temp_buf[count] = '\0';
  sscanf(temp_buf, "%d", var);

  return count;
}

static ssize_t read_proc_def_interval_ns(struct file *file, char __user *buf,
                                         size_t count, loff_t *offset) {
  return read_proc(file, buf, count, offset, &def_interval_ns);
}

static ssize_t read_proc_dump_reset_sec(struct file *file, char __user *buf,
                                        size_t count, loff_t *offset) {
  return read_proc(file, buf, count, offset, &dump_reset_sec);
}

static ssize_t write_proc_def_interval_ns(struct file *file,
                                          const char __user *buf, size_t count,
                                          loff_t *offset) {
  return write_proc(file, buf, count, offset, &def_interval_ns);
}

static ssize_t write_proc_dump_reset_sec(struct file *file,
                                         const char __user *buf, size_t count,
                                         loff_t *offset) {
  return write_proc(file, buf, count, offset, &dump_reset_sec);
}

static const struct proc_ops proc_def_interval_ns_ops = {
    .proc_read = read_proc_def_interval_ns,
    .proc_write = write_proc_def_interval_ns,
};

static const struct proc_ops proc_dump_reset_sec_ops = {
    .proc_read = read_proc_dump_reset_sec,
    .proc_write = write_proc_dump_reset_sec,
};

int monitor_proc_init(void) {
  struct proc_dir_entry *dir;

  dir = proc_mkdir(proc_dir, NULL);
  if (!dir) {
    pr_err("variable_monitor: failed to create /proc directory\n");
    return -ENOMEM;
  }

  proc_create("def_interval_ns", 0666, dir, &proc_def_interval_ns_ops);
  proc_create("dump_reset_sec", 0666, dir, &proc_dump_reset_sec_ops);

  return 0;
}

int monitor_proc_exit(void) {
  remove_proc_entry("def_interval_ns", NULL);
  remove_proc_entry("dump_reset_sec", NULL);
  remove_proc_entry(proc_dir, NULL);
  return 0;
}