#include "monitor_kernel.h"

#include <linux/cdev.h> // for cdev
#include <linux/device.h>
#include <linux/fs.h>
#include <linux/kernel.h>
#include <linux/mm.h>
#include <linux/module.h>
#include <linux/slab.h> // for kmalloc

#define DEVICE_NAME "variable_monitor"

// for character device
static dev_t dev_num;
static struct cdev *watch_cdev;
static struct class *watch_class;

struct my_device_data {
  pid_t pid;
};

static int device_open(struct inode *inode, struct file *file) {
  struct my_device_data *data;
  printk(KERN_INFO "variable_monitor open device with pid %d\n", current->pid);
  // save pid
  data = kmalloc(sizeof(*data), GFP_KERNEL);
  if (!data)
    return -ENOMEM;
  data->pid = current->pid;
  file->private_data = data;
  return 0;
}

static int device_release(struct inode *inode, struct file *file) {
  // load pid
  struct my_device_data *data = file->private_data;
  printk(KERN_INFO "variable_monitor release device with pid %d\n", data->pid);
  // clear watch with pid
  clear_watch(data->pid);
  kfree(data); // free data memory
  return 0;
}

typedef struct {
  int id;
} ioctl_id;

static long device_ioctl(struct file *file, unsigned int ioctl_num,
                         unsigned long ioctl_param) {
  int ret = 0;
  watch_arg warg;
  ioctl_dump_param dump_param;
  ioctl_id wid;

  printk(KERN_INFO "variable_monitor fun: %s with ioctl_num %d\n", __FUNCTION__,
         ioctl_num);
  switch (ioctl_num) {
  case IOCTL_WATCH_VARIABLE:
    // copy watch_arg
    if (copy_from_user(&warg, (watch_arg *)ioctl_param, sizeof(warg))) {
      return -EACCES;
    }
    printk(KERN_INFO "Watch_arg: task_id=%d, name=%s, ptr=%p, length_byte=%d, "
                     "time_ns=%ld, threshold=%lld\n",
           warg.task_id, warg.name, warg.ptr, warg.length_byte, warg.time_ns,
           warg.threshold);
    warg.time_ns =
        warg.time_ns == 0 ? def_interval_ns : warg.time_ns; // default 10us
    // start watch variable
    ret = start_watch_variable(warg);
    if (ret) {
      printk(KERN_INFO "start_watch_variable failed\n");
    }
    break;
  case IOCTL_DUMP_LOG:
    printk(KERN_INFO "variable_monitor IOCTL_DUMP_LOG\n");
    ret = copy_from_user(&dump_param, (ioctl_dump_param *)ioctl_param,
                         sizeof(ioctl_dump_param));
    printk(KERN_INFO "dump_param: %p %d %p\n", dump_param.user_ptr_len,
           dump_param.user_buf_len, dump_param.user_buf);
    if (!ret) {
      ret = copy_to_user_variant_buffer(
          &load_monitor_variant_buffer, dump_param.user_ptr_len,
          dump_param.user_buf, dump_param.user_buf_len);
      printk(KERN_INFO "ret %d, %d\n", ret, dump_param.user_buf_len);
    }
    // printk(KERN_INFO "copy_to_user_variant_buffer \n");
    break;
  case IOCTL_PID:
    printk(KERN_INFO "variable_monitor PID\n");
    ret = copy_from_user(&wid, (ioctl_id *)ioctl_param, sizeof(ioctl_id));
    diag_pid(wid.id);
    break;
  case IOCTL_TGID:
    printk(KERN_INFO "variable_monitor TGID\n");
    ret = copy_from_user(&wid, (ioctl_id *)ioctl_param, sizeof(ioctl_id));
    diag_tgid(wid.id);
    break;
  default:
    break;
  }
  return 0;
}

static struct file_operations fops = {
    .open = device_open,
    .release = device_release,
    .unlocked_ioctl = device_ioctl,
};

int init_module(void) {
  printk(KERN_INFO "variable_monitor fun: %s\n", __FUNCTION__);
  if (alloc_chrdev_region(&dev_num, 0, 1, DEVICE_NAME) < 0) {
    printk(KERN_ALERT "Failed to register device number\n");
    return -1;
  }

  if ((watch_class = class_create(THIS_MODULE, DEVICE_NAME)) == NULL) {
    printk(KERN_ALERT "Failed to create class\n");
    cdev_del(watch_cdev);
    unregister_chrdev_region(dev_num, 1);
    return -1;
  }

  if (device_create(watch_class, NULL, dev_num, NULL, DEVICE_NAME) == NULL) {
    printk(KERN_ALERT "Failed to create device\n");
    class_destroy(watch_class);
    cdev_del(watch_cdev);
    unregister_chrdev_region(dev_num, 1);
    return -1;
  }

  if ((watch_cdev = cdev_alloc()) == NULL) {
    printk(KERN_ALERT "Failed to allocate cdev structure\n");
    unregister_chrdev_region(dev_num, 1);
    return -1;
  }

  cdev_init(watch_cdev, &fops);
  if (cdev_add(watch_cdev, dev_num, 1) == -1) {
    printk(KERN_ALERT "Failed to add cdev structure\n");
    device_destroy(watch_class, dev_num);
    class_destroy(watch_class);
    unregister_chrdev_region(dev_num, 1);
    return -1;
  }

  printk(KERN_INFO "dev number: %d\n", dev_num);
  printk(KERN_INFO "path: /dev/%s %d\n", DEVICE_NAME, dev_num);

  // proc
  monitor_proc_init();

  // orig_X | buffer
  monitor_init();

  return 0;
}

void cleanup_module(void) {
  printk(KERN_INFO "variable_monitor fun: %s\n", __FUNCTION__);
  // clear all watch | free buffer
  monitor_exit();

  // proc
  monitor_proc_exit();

  // unmount
  device_destroy(watch_class, dev_num);
  class_destroy(watch_class);
  cdev_del(watch_cdev);
  unregister_chrdev_region(dev_num, 1);
}

MODULE_LICENSE("GPL");