/*
 *
 * Conky, a system monitor, based on torsmo
 *
 * Any original torsmo code is licensed under the BSD license
 *
 * All code written since the fork of torsmo is licensed under the GPL
 *
 * Please see COPYING for details
 *
 * Copyright (c) 2005 Adi Zaimi, Dan Piponi <dan@tanelorn.demon.co.uk>,
 *					  Dave Clark <clarkd@skynet.ca>
 * Copyright (c) 2005-2021 Brenden Matthews, Philip Kovacs, et. al.
 *	(see AUTHORS)
 * All rights reserved.
 *
 * This program is free software: you can redistribute it and/or modify
 * it under the terms of the GNU General Public License as published by
 * the Free Software Foundation, either version 3 of the License, or
 * (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU General Public License for more details.
 * You should have received a copy of the GNU General Public License
 * along with this program.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

#include "top.h"
#include "logging.h"
#include "prioqueue.h"

/* hash table size - always a power of 2 */
#define HTABSIZE 256

struct process *first_process = nullptr;

unsigned long g_time = 0;

/* a simple hash table to speed up find_process() */
struct proc_hash_entry {
  struct proc_hash_entry *next;
  struct process *proc;
};
static struct proc_hash_entry proc_hash_table[HTABSIZE];

static void hash_process(struct process *p) {
  struct proc_hash_entry *phe;
  static char first_run = 1;
  int bucket;

  /* better make sure all next pointers are zero upon first access */
  if (first_run != 0) {
    memset(proc_hash_table, 0, sizeof(struct proc_hash_entry) * HTABSIZE);
    first_run = 0;
  }

  /* get the bucket index */
  bucket = p->pid & (HTABSIZE - 1);

  /* insert a new element on bucket's top */
  phe = static_cast<struct proc_hash_entry *>(
      malloc(sizeof(struct proc_hash_entry)));
  phe->proc = p;
  phe->next = proc_hash_table[bucket].next;
  proc_hash_table[bucket].next = phe;
}

static void unhash_process(struct process *p) {
  struct proc_hash_entry *phe, *tmp;

  /* get the bucket head */
  phe = &proc_hash_table[p->pid & (HTABSIZE - 1)];
  /* find the entry pointing to p and drop it */
  while (phe->next != nullptr) {
    if (phe->next->proc == p) {
      tmp = phe->next;
      phe->next = phe->next->next;
      free(tmp);
      return;
    }
    phe = phe->next;
  }
}

static void __unhash_all_processes(struct proc_hash_entry *phe) {
  if (phe->next != nullptr) { __unhash_all_processes(phe->next); }
  free(phe->next);
}

static void unhash_all_processes() {
  int i;

  for (i = 0; i < HTABSIZE; i++) {
    __unhash_all_processes(&proc_hash_table[i]);
    proc_hash_table[i].next = nullptr;
  }
}

struct process *get_first_process() { return first_process; }

void free_all_processes() {
  struct process *next = nullptr, *pr = first_process;

  while (pr != nullptr) {
    next = pr->next;
    free_and_zero(pr->name);
    free_and_zero(pr->basename);
    free(pr);
    pr = next;
  }
  first_process = nullptr;

  /* drop the whole hash table */
  unhash_all_processes();
}

struct process *get_process_by_name(const char *name) {
  struct process *p = first_process;

  while (p != nullptr) {
    /* Try matching against the full command line first. If that fails,
     * fall back to the basename.
     */
    if (((p->name != nullptr) && (strcmp(p->name, name) == 0)) ||
        ((p->basename != nullptr) && (strcmp(p->basename, name) == 0))) {
      return p;
    }
    p = p->next;
  }
  return nullptr;
}

static struct process *find_process(pid_t pid) {
  struct proc_hash_entry *phe;

  phe = &proc_hash_table[pid & (HTABSIZE - 1)];
  while (phe->next != nullptr) {
    if (phe->next->proc->pid == pid) { return phe->next->proc; }
    phe = phe->next;
  }
  return nullptr;
}

static struct process *new_process(pid_t pid) {
  auto *p = static_cast<struct process *>(malloc(sizeof(struct process)));

  /* Do stitching necessary for doubly linked list */
  p->previous = nullptr;
  p->next = first_process;
  if (p->next != nullptr) { p->next->previous = p; }
  first_process = p;

  p->pid = pid;
  p->name = nullptr;
  p->basename = nullptr;
  p->amount = 0;
  p->user_time = 0;
  p->total = 0;
  p->kernel_time = 0;
  p->previous_user_time = ULONG_MAX;
  p->previous_kernel_time = ULONG_MAX;
  p->total_cpu_time = 0;
  p->vsize = 0;
  p->rss = 0;
#ifdef BUILD_IOSTATS
  p->read_bytes = 0;
  p->previous_read_bytes = ULLONG_MAX;
  p->write_bytes = 0;
  p->previous_write_bytes = ULLONG_MAX;
  p->io_perc = 0;
#endif /* BUILD_IOSTATS */
  p->time_stamp = 0;
  p->counted = 1;
  p->changed = 0;

  /* process_find_name(p); */

  /* add the process to the hash table */
  hash_process(p);

  return p;
}

/* Get / create a new process object and insert it into the process list */
struct process *get_process(pid_t pid) {
  struct process *p = find_process(pid);
  return p != nullptr ? p : new_process(pid);
}

/******************************************
 * Functions							  *
 ******************************************/

/******************************************
 * Destroy and remove a process           *
 ******************************************/

static void delete_process(struct process *p) {
#if defined(PARANOID)
  assert(p->id == 0x0badfeed);

  /*
   * Ensure that deleted processes aren't reused.
   */
  p->id = 0x007babe;
#endif /* defined(PARANOID) */

  /*
   * Maintain doubly linked list.
   */
  if (p->next != nullptr) { p->next->previous = p->previous; }
  if (p->previous != nullptr) {
    p->previous->next = p->next;
  } else {
    first_process = p->next;
  }

  free_and_zero(p->name);
  free_and_zero(p->basename);
  /* remove the process from the hash table */
  unhash_process(p);
  free(p);
}

/******************************************
 * Strip dead process entries			  *
 ******************************************/

static void process_cleanup() {
  struct process *p = first_process;

  while (p != nullptr) {
    struct process *current = p;

#if defined(PARANOID)
    assert(p->id == 0x0badfeed);
#endif /* defined(PARANOID) */

    p = p->next;
    /* Delete processes that have died */
    if (current->time_stamp != g_time) {
      delete_process(current);
      if (current == first_process) { first_process = nullptr; }
      current = nullptr;
    }
  }
}

/******************************************
 * Find the top processes				  *
 ******************************************/

/* cpu comparison function for prio queue */
static int compare_cpu(void *va, void *vb) {
  auto *a = static_cast<struct process *>(va),
       *b = static_cast<struct process *>(vb);

  if (b->amount > a->amount) { return 1; }
  if (a->amount > b->amount) { return -1; }
  return 0;
}

/* mem comparison function for prio queue */
static int compare_mem(void *va, void *vb) {
  auto *a = static_cast<struct process *>(va),
       *b = static_cast<struct process *>(vb);

  if (b->rss > a->rss) { return 1; }
  if (a->rss > b->rss) { return -1; }
  return 0;
}

/* CPU time comparison function for prio queue */
static int compare_time(void *va, void *vb) {
  auto *a = static_cast<struct process *>(va),
       *b = static_cast<struct process *>(vb);

  if (b->total_cpu_time > a->total_cpu_time) { return 1; }
  if (b->total_cpu_time < a->total_cpu_time) { return -1; }
  return 0;
}

#ifdef BUILD_IOSTATS
/* I/O comparison function for prio queue */
static int compare_io(void *va, void *vb) {
  auto *a = static_cast<struct process *>(va),
       *b = static_cast<struct process *>(vb);

  if (b->io_perc > a->io_perc) { return 1; }
  if (a->io_perc > b->io_perc) { return -1; }
  return 0;
}
#endif /* BUILD_IOSTATS */

/* ****************************************************************** *
 * Get a sorted list of the top cpu hogs and top mem hogs. * Results are stored
 * in the cpu,mem arrays in decreasing order[0-9]. *
 * ****************************************************************** */

static void process_find_top(struct process **cpu, struct process **mem,
                             struct process **ptime
#ifdef BUILD_IOSTATS
                             ,
                             struct process **io
#endif /* BUILD_IOSTATS */
) {
  prio_queue_t cpu_queue, mem_queue, time_queue;
#ifdef BUILD_IOSTATS
  prio_queue_t io_queue;
#endif
  struct process *cur_proc = nullptr;
  int i;

  if ((top_cpu == 0) && (top_mem == 0) && (top_time == 0)
#ifdef BUILD_IOSTATS
      && (top_io == 0)
#endif /* BUILD_IOSTATS */
      && (top_running == 0)) {
    return;
  }

  cpu_queue = init_prio_queue();
  pq_set_compare(cpu_queue, &compare_cpu);
  pq_set_max_size(cpu_queue, MAX_SP);

  mem_queue = init_prio_queue();
  pq_set_compare(mem_queue, &compare_mem);
  pq_set_max_size(mem_queue, MAX_SP);

  time_queue = init_prio_queue();
  pq_set_compare(time_queue, &compare_time);
  pq_set_max_size(time_queue, MAX_SP);

#ifdef BUILD_IOSTATS
  io_queue = init_prio_queue();
  pq_set_compare(io_queue, &compare_io);
  pq_set_max_size(io_queue, MAX_SP);
#endif

  /* g_time is the time_stamp entry for process.  It is updated when the
   * process information is updated to indicate that the process is still
   * alive (and must not be removed from the process list in
   * process_cleanup()) */
  ++g_time;

  /* OS-specific function updating process list */
  get_top_info();

  process_cleanup(); /* cleanup list from exited processes */

  cur_proc = first_process;

  while (cur_proc != nullptr) {
    if (top_cpu != 0) { insert_prio_elem(cpu_queue, cur_proc); }
    if (top_mem != 0) { insert_prio_elem(mem_queue, cur_proc); }
    if (top_time != 0) { insert_prio_elem(time_queue, cur_proc); }
#ifdef BUILD_IOSTATS
    if (top_io != 0) { insert_prio_elem(io_queue, cur_proc); }
#endif /* BUILD_IOSTATS */
    cur_proc = cur_proc->next;
  }

  for (i = 0; i < MAX_SP; i++) {
    if (top_cpu != 0) {
      cpu[i] = static_cast<process *>(pop_prio_elem(cpu_queue));
    }
    if (top_mem != 0) {
      mem[i] = static_cast<process *>(pop_prio_elem(mem_queue));
    }
    if (top_time != 0) {
      ptime[i] = static_cast<process *>(pop_prio_elem(time_queue));
    }
#ifdef BUILD_IOSTATS
    if (top_io != 0) {
      io[i] = static_cast<process *>(pop_prio_elem(io_queue));
    }
#endif /* BUILD_IOSTATS */
  }
  free_prio_queue(cpu_queue);
  free_prio_queue(mem_queue);
  free_prio_queue(time_queue);
#ifdef BUILD_IOSTATS
  free_prio_queue(io_queue);
#endif /* BUILD_IOSTATS */
}

int update_top() {
  // if nothing else has ever set up info, we need to update it here, because
  // info.memmax is used to print percentages in `print_top_mem`
  if (info.memmax == 0) {
    update_meminfo();
  }
  process_find_top(info.cpu, info.memu, info.time
#ifdef BUILD_IOSTATS
                   ,
                   info.io
#endif
  );
  info.first_process = get_first_process();
  return 0;
}

static char *format_time(unsigned long timeval, const int width) {
  char buf[10];
  unsigned long nt;  // narrow time, for speed on 32-bit
  unsigned cc;       // centiseconds
  unsigned nn;       // multi-purpose whatever

  nt = timeval;
  cc = nt % 100;  // centiseconds past second
  nt /= 100;      // total seconds
  nn = nt % 60;   // seconds past the minute
  nt /= 60;       // total minutes
  if (width >= snprintf(buf, sizeof buf, "%lu:%02u.%02u", nt, nn, cc)) {
    return strndup(buf, text_buffer_size.get(*state));
  }
  if (width >= snprintf(buf, sizeof buf, "%lu:%02u", nt, nn)) {
    return strndup(buf, text_buffer_size.get(*state));
  }
  nn = nt % 60;  // minutes past the hour
  nt /= 60;      // total hours
  if (width >= snprintf(buf, sizeof buf, "%lu,%02u", nt, nn)) {
    return strndup(buf, text_buffer_size.get(*state));
  }
  nn = nt;  // now also hours
  if (width >= snprintf(buf, sizeof buf, "%uh", nn)) {
    return strndup(buf, text_buffer_size.get(*state));
  }
  nn /= 24;  // now days
  if (width >= snprintf(buf, sizeof buf, "%ud", nn)) {
    return strndup(buf, text_buffer_size.get(*state));
  }
  nn /= 7;  // now weeks
  if (width >= snprintf(buf, sizeof buf, "%uw", nn)) {
    return strndup(buf, text_buffer_size.get(*state));
  }
  // well shoot, this outta' fit...
  return strndup("<inf>", text_buffer_size.get(*state));
}

struct top_data {
  struct process **list;
  int num;
  int was_parsed;
  char *s;
};

static conky::range_config_setting<unsigned int> top_name_width(
    "top_name_width", 0, std::numeric_limits<unsigned int>::max(), 15, true);
static conky::simple_config_setting<bool> top_name_verbose("top_name_verbose",
                                                           false, true);

static void print_top_name(struct text_object *obj, char *p,
                           unsigned int p_max_size) {
  auto *td = static_cast<struct top_data *>(obj->data.opaque);
  int width;

  if ((td == nullptr) || (td->list == nullptr) ||
      (td->list[td->num] == nullptr)) {
    return;
  }

  width = std::min(p_max_size,
                   static_cast<unsigned int>(top_name_width.get(*state)) + 1);
  if (top_name_verbose.get(*state)) {
    /* print the full command line */
    snprintf(p, width + 1, "%-*s", width, td->list[td->num]->name);
  } else {
    /* print only the basename (i.e. executable name) */
    snprintf(p, width + 1, "%-*s", width, td->list[td->num]->basename);
  }
}

static void print_top_mem(struct text_object *obj, char *p,
                          unsigned int p_max_size) {
  auto *td = static_cast<struct top_data *>(obj->data.opaque);
  int width;

  if ((td == nullptr) || (td->list == nullptr) ||
      (td->list[td->num] == nullptr)) {
    return;
  }

  width = std::min(p_max_size, static_cast<unsigned int>(7));
  snprintf(p, width, "%6.2f",
           (static_cast<float>(td->list[td->num]->rss) / info.memmax) / 10);
}

static void print_top_time(struct text_object *obj, char *p,
                           unsigned int p_max_size) {
  auto *td = static_cast<struct top_data *>(obj->data.opaque);
  int width;
  char *timeval;

  if ((td == nullptr) || (td->list == nullptr) ||
      (td->list[td->num] == nullptr)) {
    return;
  }

  width = std::min(p_max_size, static_cast<unsigned int>(10));
  timeval = format_time(td->list[td->num]->total_cpu_time, 9);
  snprintf(p, width, "%9s", timeval);
  free(timeval);
}

static void print_top_user(struct text_object *obj, char *p,
                           unsigned int p_max_size) {
  auto *td = static_cast<struct top_data *>(obj->data.opaque);
  struct passwd *pw;

  if ((td == nullptr) || (td->list == nullptr) ||
      (td->list[td->num] == nullptr)) {
    return;
  }

  pw = getpwuid(td->list[td->num]->uid);
  if (pw != nullptr) {
    snprintf(p, p_max_size, "%.8s", pw->pw_name);
  } else {
    snprintf(p, p_max_size, "%d", td->list[td->num]->uid);
  }
}

#define PRINT_TOP_GENERATOR(name, width, fmt, field)                         \
  static void print_top_##name(struct text_object *obj, char *p,             \
                               unsigned int p_max_size) {                    \
    struct top_data *td = (struct top_data *)obj->data.opaque;               \
    if (!td || !td->list || !td->list[td->num]) return;                      \
    snprintf(p, std::min(p_max_size, width), fmt, td->list[td->num]->field); \
  }

#define PRINT_TOP_HR_GENERATOR(name, field, denom)                     \
  static void print_top_##name(struct text_object *obj, char *p,       \
                               unsigned int p_max_size) {              \
    struct top_data *td = (struct top_data *)obj->data.opaque;         \
    if (!td || !td->list || !td->list[td->num]) return;                \
    human_readable(td->list[td->num]->field / (denom), p, p_max_size); \
  }

PRINT_TOP_GENERATOR(cpu, (unsigned int)7, "%6.2f", amount)
PRINT_TOP_GENERATOR(pid, (unsigned int)8, "%7i", pid)
PRINT_TOP_GENERATOR(uid, (unsigned int)6, "%5i", uid)
PRINT_TOP_HR_GENERATOR(mem_res, rss, 1)
PRINT_TOP_HR_GENERATOR(mem_vsize, vsize, 1)
#ifdef BUILD_IOSTATS
PRINT_TOP_HR_GENERATOR(read_bytes, read_bytes, active_update_interval())
PRINT_TOP_HR_GENERATOR(write_bytes, write_bytes, active_update_interval())
PRINT_TOP_GENERATOR(io_perc, (unsigned int)7, "%6.2f", io_perc)
#endif /* BUILD_IOSTATS */

static void free_top(struct text_object *obj) {
  auto *td = static_cast<struct top_data *>(obj->data.opaque);

  if (td == nullptr) { return; }
  free_and_zero(td->s);
  free_and_zero(obj->data.opaque);
}

int parse_top_args(const char *s, const char *arg, struct text_object *obj) {
  struct top_data *td;
  char buf[64];
  int n;

  if (arg == nullptr) {
    NORM_ERR("top needs arguments");
    return 0;
  }

  obj->data.opaque = td =
      static_cast<struct top_data *>(malloc(sizeof(struct top_data)));
  memset(td, 0, sizeof(struct top_data));

  if (s[3] == 0) {
    td->list = info.cpu;
    top_cpu = 1;
  } else if (strcmp(&s[3], "_mem") == EQUAL) {
    td->list = info.memu;
    top_mem = 1;
  } else if (strcmp(&s[3], "_time") == EQUAL) {
    td->list = info.time;
    top_time = 1;
#ifdef BUILD_IOSTATS
  } else if (strcmp(&s[3], "_io") == EQUAL) {
    td->list = info.io;
    top_io = 1;
#endif /* BUILD_IOSTATS */
  } else {
#ifdef BUILD_IOSTATS
    NORM_ERR("Must be top, top_mem, top_time or top_io");
#else  /* BUILD_IOSTATS */
    NORM_ERR("Must be top, top_mem or top_time");
#endif /* BUILD_IOSTATS */
    free_and_zero(obj->data.opaque);
    return 0;
  }

  td->s = strndup(arg, text_buffer_size.get(*state));

  if (sscanf(arg, "%63s %i", buf, &n) == 2) {
    if (strcmp(buf, "name") == EQUAL) {
      obj->callbacks.print = &print_top_name;
    } else if (strcmp(buf, "cpu") == EQUAL) {
      obj->callbacks.print = &print_top_cpu;
    } else if (strcmp(buf, "pid") == EQUAL) {
      obj->callbacks.print = &print_top_pid;
    } else if (strcmp(buf, "mem") == EQUAL) {
      obj->callbacks.print = &print_top_mem;
    } else if (strcmp(buf, "time") == EQUAL) {
      obj->callbacks.print = &print_top_time;
    } else if (strcmp(buf, "mem_res") == EQUAL) {
      obj->callbacks.print = &print_top_mem_res;
    } else if (strcmp(buf, "mem_vsize") == EQUAL) {
      obj->callbacks.print = &print_top_mem_vsize;
    } else if (strcmp(buf, "uid") == EQUAL) {
      obj->callbacks.print = &print_top_uid;
    } else if (strcmp(buf, "user") == EQUAL) {
      obj->callbacks.print = &print_top_user;
#ifdef BUILD_IOSTATS
    } else if (strcmp(buf, "io_read") == EQUAL) {
      obj->callbacks.print = &print_top_read_bytes;
    } else if (strcmp(buf, "io_write") == EQUAL) {
      obj->callbacks.print = &print_top_write_bytes;
    } else if (strcmp(buf, "io_perc") == EQUAL) {
      obj->callbacks.print = &print_top_io_perc;
#endif /* BUILD_IOSTATS */
    } else {
      NORM_ERR("invalid type arg for top");
#ifdef BUILD_IOSTATS
      NORM_ERR(
          "must be one of: name, cpu, pid, mem, time, mem_res, mem_vsize, "
          "io_read, io_write, io_perc");
#else  /* BUILD_IOSTATS */
      NORM_ERR("must be one of: name, cpu, pid, mem, time, mem_res, mem_vsize");
#endif /* BUILD_IOSTATS */
      free_and_zero(td->s);
      free_and_zero(obj->data.opaque);
      return 0;
    }
    if (n < 1 || n > MAX_SP) {
      NORM_ERR("invalid num arg for top. Must be between 1 and %d.", MAX_SP);
      free_and_zero(td->s);
      free_and_zero(obj->data.opaque);
      return 0;
    }
    td->num = n - 1;

  } else {
    NORM_ERR("invalid argument count for top");
    free_and_zero(td->s);
    free_and_zero(obj->data.opaque);
    return 0;
  }
  obj->callbacks.free = &free_top;
  return 1;
}