// This is an open source non-commercial project. Dear PVS-Studio, please check
// it. PVS-Studio Static Code Analyzer for C, C++ and C#: http://www.viva64.com

#include <assert.h>
#include <math.h>
#include <stdio.h>

#include "nvim/assert.h"
#include "nvim/func_attr.h"
#include "nvim/globals.h"  // for the global `time_fd` (startuptime)
#include "nvim/os/os_defs.h"
#include "nvim/os/time.h"
#include "nvim/profile.h"

#ifdef INCLUDE_GENERATED_DECLARATIONS
# include "profile.c.generated.h"
#endif

static proftime_T prof_wait_time;

/// Gets the current time.
///
/// @return the current time
proftime_T profile_start(void) FUNC_ATTR_WARN_UNUSED_RESULT
{
  return os_hrtime();
}

/// Computes the time elapsed.
///
/// @return Elapsed time from `tm` until now.
proftime_T profile_end(proftime_T tm) FUNC_ATTR_WARN_UNUSED_RESULT
{
  return profile_sub(os_hrtime(), tm);
}

/// Gets a string representing time `tm`.
///
/// @warning Do not modify or free this string, not multithread-safe.
///
/// @param tm Time
/// @return Static string representing `tm` in the form "seconds.microseconds".
const char *profile_msg(proftime_T tm) FUNC_ATTR_WARN_UNUSED_RESULT
{
  static char buf[50];
  snprintf(buf, sizeof(buf), "%10.6lf",
           (double)profile_signed(tm) / 1000000000.0);
  return buf;
}

/// Gets the time `msec` into the future.
///
/// @param msec milliseconds, the maximum number of milliseconds is
///             (2^63 / 10^6) - 1 = 9.223372e+12.
/// @return if msec > 0, returns the time msec past now. Otherwise returns
///         the zero time.
proftime_T profile_setlimit(int64_t msec) FUNC_ATTR_WARN_UNUSED_RESULT
{
  if (msec <= 0) {
    // no limit
    return profile_zero();
  }
  assert(msec <= (INT64_MAX / 1000000LL) - 1);
  proftime_T nsec = (proftime_T)msec * 1000000ULL;
  return os_hrtime() + nsec;
}

/// Checks if current time has passed `tm`.
///
/// @return true if the current time is past `tm`, false if not or if the
///         timer was not set.
bool profile_passed_limit(proftime_T tm) FUNC_ATTR_WARN_UNUSED_RESULT
{
  if (tm == 0) {
    // timer was not set
    return false;
  }

  return profile_cmp(os_hrtime(), tm) < 0;
}

/// Gets the zero time.
///
/// @return the zero time
proftime_T profile_zero(void) FUNC_ATTR_CONST
{
  return 0;
}

/// Divides time `tm` by `count`.
///
/// @return 0 if count <= 0, otherwise tm / count
proftime_T profile_divide(proftime_T tm, int count) FUNC_ATTR_CONST
{
  if (count <= 0) {
    return profile_zero();
  }

  return (proftime_T)round((double)tm / (double)count);
}

/// Adds time `tm2` to `tm1`.
///
/// @return `tm1` + `tm2`
proftime_T profile_add(proftime_T tm1, proftime_T tm2) FUNC_ATTR_CONST
{
  return tm1 + tm2;
}

/// Subtracts time `tm2` from `tm1`.
///
/// Unsigned overflow (wraparound) occurs if `tm2` is greater than `tm1`.
/// Use `profile_signed()` to get the signed integer value.
///
/// @see profile_signed
///
/// @return `tm1` - `tm2`
proftime_T profile_sub(proftime_T tm1, proftime_T tm2) FUNC_ATTR_CONST
{
  return tm1 - tm2;
}

/// Adds the `self` time from the total time and the `children` time.
///
/// @return if `total` <= `children`, then self, otherwise `self` + `total` -
///         `children`
proftime_T profile_self(proftime_T self, proftime_T total, proftime_T children)
  FUNC_ATTR_CONST
{
  // check that the result won't be negative, which can happen with
  // recursive calls.
  if (total <= children) {
    return self;
  }

  // add the total time to self and subtract the children's time from self
  return profile_sub(profile_add(self, total), children);
}

/// Gets the current waittime.
///
/// @return the current waittime
proftime_T profile_get_wait(void) FUNC_ATTR_PURE
{
  return prof_wait_time;
}

/// Sets the current waittime.
void profile_set_wait(proftime_T wait)
{
  prof_wait_time = wait;
}

/// Subtracts the passed waittime since `tm`.
///
/// @return `tma` - (waittime - `tm`)
proftime_T profile_sub_wait(proftime_T tm, proftime_T tma) FUNC_ATTR_PURE
{
  proftime_T tm3 = profile_sub(profile_get_wait(), tm);
  return profile_sub(tma, tm3);
}

/// Checks if time `tm1` is equal to `tm2`.
///
/// @return true if `tm1` == `tm2`
bool profile_equal(proftime_T tm1, proftime_T tm2) FUNC_ATTR_CONST
{
  return tm1 == tm2;
}

/// Converts time duration `tm` (`profile_sub` result) to a signed integer.
///
/// @return signed representation of the given time value
int64_t profile_signed(proftime_T tm)
  FUNC_ATTR_CONST
{
  // (tm > INT64_MAX) is >=150 years, so we can assume it was produced by
  // arithmetic of two proftime_T values.  For human-readable representation
  // (and Vim-compat) we want the difference after unsigned wraparound. #10452
  return (tm <= INT64_MAX) ? (int64_t)tm : -(int64_t)(UINT64_MAX - tm);
}

/// Compares profiling times.
///
/// Times `tm1` and `tm2` must be less than 150 years apart.
///
/// @return <0: `tm2` < `tm1`
///          0: `tm2` == `tm1`
///         >0: `tm2` > `tm1`
int profile_cmp(proftime_T tm1, proftime_T tm2) FUNC_ATTR_CONST
{
  if (tm1 == tm2) {
    return 0;
  }
  return profile_signed(tm2 - tm1) < 0 ? -1 : 1;
}

/// globals for use in the startuptime related functionality (time_*).
static proftime_T g_start_time;
static proftime_T g_prev_time;

/// Saves the previous time before doing something that could nest.
///
/// After calling this function, the static global `g_prev_time` will
/// contain the current time.
///
/// @param[out] rel to the time elapsed so far
/// @param[out] start the current time
void time_push(proftime_T *rel, proftime_T *start)
{
  proftime_T now = profile_start();

  // subtract the previous time from now, store it in `rel`
  *rel = profile_sub(now, g_prev_time);
  *start = now;

  // reset global `g_prev_time` for the next call
  g_prev_time = now;
}

/// Computes the prev time after doing something that could nest.
///
/// Subtracts `tp` from the static global `g_prev_time`.
///
/// @param tp the time to subtract
void time_pop(proftime_T tp)
{
  g_prev_time -= tp;
}

/// Prints the difference between `then` and `now`.
///
/// the format is "msec.usec".
static void time_diff(proftime_T then, proftime_T now)
{
  proftime_T diff = profile_sub(now, then);
  fprintf(time_fd, "%07.3lf", (double)diff / 1.0E6);
}

/// Initializes the startuptime code.
///
/// Must be called once before calling other startuptime code (such as
/// time_{push,pop,msg,...}).
///
/// @param message the message that will be displayed
void time_start(const char *message)
{
  if (time_fd == NULL) {
    return;
  }

  // initialize the global variables
  g_prev_time = g_start_time = profile_start();

  fprintf(time_fd, "\n\ntimes in msec\n");
  fprintf(time_fd, " clock   self+sourced   self:  sourced script\n");
  fprintf(time_fd, " clock   elapsed:              other lines\n\n");

  time_msg(message, NULL);
}

/// Prints out timing info.
///
/// @warning don't forget to call `time_start()` once before calling this.
///
/// @param mesg the message to display next to the timing information
/// @param start only for do_source: start time
void time_msg(const char *mesg, const proftime_T *start)
{
  if (time_fd == NULL) {
    return;
  }

  // print out the difference between `start` (init earlier) and `now`
  proftime_T now = profile_start();
  time_diff(g_start_time, now);

  // if `start` was supplied, print the diff between `start` and `now`
  if (start != NULL) {
    fprintf(time_fd, "  ");
    time_diff(*start, now);
  }

  // print the difference between the global `g_prev_time` and `now`
  fprintf(time_fd, "  ");
  time_diff(g_prev_time, now);

  // reset `g_prev_time` and print the message
  g_prev_time = now;
  fprintf(time_fd, ": %s\n", mesg);
}
