#include "monitor_kernel.h"

#include <linux/sched.h>
// #include <linux/sched/task.h>
// #include <linux/sched/mm.h>

#define __task_contributes_to_load(task)                                       \
  ((READ_ONCE(task->__state) & TASK_UNINTERRUPTIBLE) != 0 &&                   \
   (task->flags & PF_FROZEN) == 0 &&                                           \
   (READ_ONCE(task->__state) & TASK_NOLOAD) == 0)

/**
 * @brief watch_arg to kernel_watch_arg
 *
 * @param ptr: kernel space address
 * @param warg: watch_arg
 * @param k_watch_arg: kernel_watch_arg
 * @return unsigned char
 */
static unsigned char w_arg2k_w_arg(void *kptr, watch_arg warg,
                                   kernel_watch_arg *k_watch_arg) {
  // k_watch_arg init
  k_watch_arg->task_id = warg.task_id;
  strncpy(k_watch_arg->name, warg.name, MAX_NAME_LEN + 1); // name
  k_watch_arg->name[MAX_NAME_LEN + 1] = '\0';              // just in case
  k_watch_arg->ptr = warg.ptr;
  k_watch_arg->kptr = kptr;
  k_watch_arg->length_byte = warg.length_byte;
  k_watch_arg->threshold = warg.threshold;
  k_watch_arg->unsigned_flag = warg.unsigned_flag;
  k_watch_arg->greater_flag = warg.greater_flag;
  return 0;
}

static void k_w_arg2threshold(kernel_watch_arg *k_watch_arg,
                              threshold *threshold) {
  threshold->task_id = k_watch_arg->task_id;
  strncpy(threshold->name, k_watch_arg->name, MAX_NAME_LEN + 1);
  threshold->name[MAX_NAME_LEN + 1] = '\0';
  threshold->ptr = k_watch_arg->ptr;
  threshold->threshold = k_watch_arg->threshold;
}

static void init_mm_tree(mm_tree *mm_tree) {
  INIT_RADIX_TREE(&mm_tree->mm_tree, GFP_ATOMIC);
  spin_lock_init(&mm_tree->mm_tree_lock);
}

static int init_buffer(unsigned int buf_size) {
  init_mm_tree(&mm_tree_struct); // init mm_tree
  init_diag_variant_buffer(&load_monitor_variant_buffer, buf_size);
  int ret = 0;
  ret = alloc_diag_variant_buffer(&load_monitor_variant_buffer);
  return ret;
}

/// @brief clear all watch and reset kernel_wtimer_list/kernel_wtimer_num
/// @param
static void clear_all_watch(void) {
  printk(KERN_INFO "clear all watch variable\n");
  // unmap and release the page
  free_all_page_list();
  // cancel timer
  cancel_all_hrTimer();
  // clear timer
  kernel_wtimer_num = 0;
  memset(kernel_wtimer_list, 0, sizeof(kernel_wtimer_list));
}

/**
 * @brief all module function init. orig_X | buffer
 *
 * @return int
 */
int monitor_init(void) {
  int ret = 0;

  ret = init_orig_fun(); // init orig_X
  if (ret)
    return ret;
  ret = init_buffer(50 * 1024 * 1024); // 50M
  if (ret)
    return -1;
  return 0;
}

/**
 * @brief monitor exit: clear all watch and free buffer
 *
 */
void monitor_exit(void) {
  // clear all watch
  clear_all_watch();
  // free buffer
  destroy_diag_variant_buffer(&load_monitor_variant_buffer);
  printk(KERN_INFO "clear all buffer\n");
}

/**
 * @brief start watch variable
 *
 * @param warg: uapi watch_arg
 * @return int 0 is success
 * !todo: adjust printk
 */
int start_watch_variable(watch_arg warg) {
  void *kptr;
  kernel_watch_timer *timer = NULL;
  kernel_watch_arg k_watch_arg;

  // user space address to kernel space address
  kptr = convert_user_space_ptr(warg.task_id, (unsigned long)warg.ptr);
  if (kptr == NULL) {
    printk(KERN_ERR "Cannot access user space\n");
    return -EACCES;
  }
  // check length
  if (warg.length_byte != 1 && warg.length_byte != 2 && warg.length_byte != 4 &&
      warg.length_byte != 8) {
    printk(KERN_ERR "Invalid length %d\n", warg.length_byte);
    return -EINVAL;
  }
  // k_watch_arg init
  w_arg2k_w_arg(kptr, warg, &k_watch_arg);
  timer = get_timer(warg.time_ns); // get a valuable timer

  printk(KERN_INFO "ptr transform kptr: %p\n", kptr);
  printk(KERN_INFO "timer: %p\n", timer);
  printk(KERN_INFO "timer->sentinel: %d, timer->time_ns: %lld\n",
         timer->sentinel, timer->time_ns);
  printk(KERN_INFO "timer->hr_timer: %p\n", &timer->hr_timer);

  TIMER_CANCEL(timer); // just in case
  timer_add_watch(timer, k_watch_arg);
  TIMER_START(timer);

  printk(KERN_INFO "Start watching var: %s\n", warg.name);
  return 0;
}

/**
 * @brief clear watch with pid
 *
 * @param pid
 */
void clear_watch(pid_t pid) {
  printk(KERN_INFO "clear pid %d 's watch variable\n", pid);
  cancel_all_hrTimer();      // just in case
  del_all_kwarg_by_pid(pid); // delete all kwarg with pid
  free_page_list(pid);       // free page with pid
  start_all_hrTimer();       // restart timer
}

/**
 * @brief main callback function
 *
 * @param timer
 * @return enum hrtimer_restart
 */
enum hrtimer_restart check_variable_cb(struct hrtimer *timer) {
  kernel_watch_timer *k_watch_timer =
      container_of(timer, kernel_watch_timer, hr_timer);
  int i = 0, j = 0;
  int buffer[TIMER_MAX_WATCH_NUM]; // Buffer to store the messages
  kernel_watch_arg *kwarg;

  // check all watched kernel_watch_arg
  for (i = 0; i < k_watch_timer->sentinel; i++) {
    kwarg = &k_watch_timer->k_watch_args[i];
    if (read_and_compare(kwarg->kptr, kwarg->length_byte, kwarg->greater_flag,
                         kwarg->unsigned_flag, kwarg->threshold)) {
      buffer[j] = i;
      j++;
    }
  }
  if (j > 0) // if any threshold reached
  {
    struct task_struct *g, *p; // g: task group; p: task
    unsigned long flags;
    variable_monitor_task tsk_info;
    unsigned long event_id = get_cycles();
    variable_monitor_record vm_record = {.id = event_id,
                                         .et_type = 1, //! todo event type
                                         .tv = ktime_get_real(),
                                         .threshold_record = {0}};

    // printk("-------------------------------------\n");
    // printk("-------------watch monitor-----------\n");
    // printk("Threshold reached:\n");
    for (i = 0; i < j; i++) {
      kwarg = &k_watch_timer->k_watch_args[buffer[i]];
      k_w_arg2threshold(kwarg, &vm_record.threshold_record[i]);
    }
    rcu_read_lock();
    diag_variant_buffer_spin_lock(&load_monitor_variant_buffer, flags);
    diag_variant_buffer_reserve(&load_monitor_variant_buffer,
                                sizeof(variable_monitor_record));
    diag_variant_buffer_write_nolock(&load_monitor_variant_buffer, &vm_record,
                                     sizeof(variable_monitor_record));
    diag_variant_buffer_seal(&load_monitor_variant_buffer);
    diag_variant_buffer_spin_unlock(&load_monitor_variant_buffer, flags);

    do_each_thread(g, p) {
      if (p->__state == TASK_RUNNING || __task_contributes_to_load(p) ||
          p->__state == TASK_IDLE) {
        tsk_info.et_type = 2; //! todo event type
        tsk_info.id = event_id;
        tsk_info.tv = vm_record.tv;

        diag_task_brief(p, &tsk_info.task);            // task brief
        diag_task_user_stack(p, &tsk_info.user_stack); // user stack
        diag_task_kern_stack(p, &tsk_info.kern_stack); // kernel stack
        dump_proc_chains_argv(1, p, &mm_tree_struct,
                              &tsk_info.proc_chains); // proc chains

        diag_variant_buffer_spin_lock(&load_monitor_variant_buffer, flags);
        diag_variant_buffer_reserve(&load_monitor_variant_buffer,
                                    sizeof(variable_monitor_task));
        diag_variant_buffer_write_nolock(&load_monitor_variant_buffer,
                                         &tsk_info,
                                         sizeof(variable_monitor_task));
        diag_variant_buffer_seal(&load_monitor_variant_buffer);
        diag_variant_buffer_spin_unlock(&load_monitor_variant_buffer, flags);
      }
    }
    while_each_thread(g, p);

    rcu_read_unlock();

    // print_task_stack();
    // restart timer after 5s
    hrtimer_forward(timer, timer->base->get_time(), ktime_set(5, 0)); //! todo
    printk("-------------------------------------\n");
  } else {
    // keep frequency
    hrtimer_forward(timer, timer->base->get_time(), k_watch_timer->kt);
  }
  return HRTIMER_RESTART; // restart timer
}