package PubMed::Dates;

use strict;
use warnings;

use Carp qw(confess);
use Date::Parse;
use Date::Format;
use Date::Calc;

use PubMed::Paths;
use PubMed::Files;

my $seconds_in_a_day=60*60*24;
my $seconds_in_a_week=7*$seconds_in_a_day;
my $format='%Y-%m-%d';

our $month_number;
$month_number->{'Jan'}='01';
$month_number->{'Feb'}='02';
$month_number->{'Mar'}='03';
$month_number->{'Apr'}='04';
$month_number->{'May'}='05';
$month_number->{'Jun'}='06';
$month_number->{'Jun'}='06';
$month_number->{'Jul'}='07';
$month_number->{'Aug'}='08';
$month_number->{'Sep'}='09';
$month_number->{'Oct'}='10';
$month_number->{'Nov'}='11';
$month_number->{'Dec'}='12';
$month_number->{'JAN'}='01';
$month_number->{'FEB'}='02';
$month_number->{'MAR'}='03';
$month_number->{'APR'}='04';
$month_number->{'MAY'}='05';
$month_number->{'JUN'}='06';
$month_number->{'JUN'}='06';
$month_number->{'JUL'}='07';
$month_number->{'AUG'}='08';
$month_number->{'SEP'}='09';
$month_number->{'OCT'}='10';
$month_number->{'NOV'}='11';
$month_number->{'DEC'}='12';
$month_number->{'JAn'}='01';
$month_number->{'FEb'}='02';
$month_number->{'MAr'}='03';
$month_number->{'APr'}='04';
$month_number->{'MAy'}='05';
$month_number->{'JUn'}='06';
$month_number->{'JUn'}='06';
$month_number->{'JUl'}='07';
$month_number->{'AUg'}='08';
$month_number->{'SEp'}='09';
$month_number->{'OCt'}='10';
$month_number->{'NOv'}='11';
$month_number->{'N0v'}='11';
$month_number->{'DEc'}='12';
$month_number->{'jan'}='01';
$month_number->{'feb'}='02';
$month_number->{'mar'}='03';
$month_number->{'apr'}='04';
$month_number->{'may'}='05';
$month_number->{'jun'}='06';
$month_number->{'jun'}='06';
$month_number->{'jul'}='07';
$month_number->{'aug'}='08';
$month_number->{'sep'}='09';
$month_number->{'oct'}='10';
$month_number->{'nov'}='11';
$month_number->{'dec'}='12';
$month_number->{'Oc'}='10';
$month_number->{'Oktober'}='10';
$month_number->{'Ene'}='01';

our $seasons_date;
$seasons_date->{'Spring'}="03-21";
$seasons_date->{'Spr'}="03-21";
$seasons_date->{'SPR'}="03-21";
$seasons_date->{'Summer'}="06-21";
$seasons_date->{'Fall'}  ="09-21";
$seasons_date->{'Fall/Winter'}  ="09-21";
$seasons_date->{'Autumn'}="09-21";
$seasons_date->{'Winter'}="12-21";
$seasons_date->{'spring'}="03-21";
$seasons_date->{'summer'}="06-21";
$seasons_date->{'fall'}  ="09-21";
$seasons_date->{'autumn'}="09-21";
$seasons_date->{'winter'}="12-21";
$seasons_date->{'SPRING'}="03-21";
$seasons_date->{'SUMMER'}="06-21";
$seasons_date->{'FALL'}  ="09-21";
$seasons_date->{'AUTUMN'}="09-21";
$seasons_date->{'WINTER'}="12-21";
$seasons_date->{'SUM'}="06-21";

sub this_year {
  return time2str('%Y',time);
}

sub get_past_weeks_from_date {
  my $number=shift // '';
  my $start_date=shift // '';
  my $dates=[];
  if(not $number=~m|^\d+|) {
    confess "I need a different number than '$number'.";
  }
  ## we never look at today's date
  if(not $number > 0) {
    return $dates;
  }
  my $start=0;
  if($start_date) {
    $start=&get_time_on_date($start_date);
    ## to start from the given day
    $start+=$seconds_in_a_day;
  }
  else {
    $start=time();
  }
  my $count=0;
  while($number>0) {
    my $time=$start - $number * $seconds_in_a_week;
    $dates->[$count++]=time2str($format,$time);
    $number--;
  }
  return $dates;
}

sub is_before {
  my $d1=shift;
  my $d2=shift;
  return $d1 cmp $d2;
}

sub get_time_on_date {
  my $date=shift;
  my $do_date="$PubMed::Paths::date -d '$date 12:00'";
  my $date_written=`$do_date`;
  chomp $date_written;
  my $time=Date::Parse::str2time($date_written);
  return $time;
}

sub date_file {
  my $file=shift // confess "I need a file here.";
  my $time=&PubMed::Files::mtime($file);
  my $date=time2str("%Y-%m-%d", $time);
  return $date;
}

sub get_past_dates_from_number {
  my $number=shift // '';
  my $start_date=shift // '';
  my $dates=[];
  if(not $number=~m|^\d+|) {
    confess "I need a different number than '$number'.";
  }
  ## we never look at today's date
  if(not $number > 0) {
    return $dates;
  }
  my $start=0;
  if($start_date) {
    $start=&get_time_on_date($start_date);
    ## to start from the given day
    $start+=$seconds_in_a_day;
  }
  else {
    $start=time();
  }
  my $count=0;
  while($number>0) {
    my $time=$start - $number * $seconds_in_a_day;
    $dates->[$count++]=time2str($format,$time);
    $number--;
  }
  return $dates;
}

sub today {
  my $time=shift // time;
  my $date=time2str("%Y-%m-%d", $time);
  return $date;
}

sub yesterday {
  my $date=`$PubMed::Paths::date -I -d 'yesterday'`;
  chomp $date;
  return $date;
}

## prepare the date if data
sub make_touch_for_date {
  my $date=shift;
  my $string="$date 12:00";
  my $time=str2time($string)
    or confess "I think you gave me invalid date '$date'";
  my $touch_date=File::Touch->new(mtime_only=>1,mtime=>$time);
  return $touch_date;
}

## later date come second
sub diff_dates {
  my $d1=shift;
  my $d2=shift;
  ## construct containing the parsed dates
  my $d;
  my $count=0;
  foreach my $in ($d1,$d2) {
    $in=~m|^(\d{4})-(\d{2})-(\d{2})$| or confess "bad date '$in'.";
    $d->[$count]->[0]=$1;
    $d->[$count]->[1]=$2;
    $d->[$count]->[2]=$3;
    $count++;
  }
  ## make sure we capture an invalid date
  my $delta;
  eval {
    $delta=Date::Calc::Delta_Days(@{$d->[0]},@{$d->[1]});
  };
  if(not defined($delta)) {
    confess "I could not compute the difference between $d1 and $d2";
  }
  return $delta;
}

sub split_date {
  my $date=shift;
  my $year=substr($date,0,4);
  my $month=substr($date,5,2);
  my $day=substr($date,8,2);
  return ($year,$month,$day);
}

sub is_date {
  my $date=shift // confess "I need a date here.";
  ## by http://umbraco.slu-art.phosdev.se/en/contact/staff/johan-soedercrantz/
  if($date=~m/^[0-9]{4}-(((0[13578]|(10|12))-(0[1-9]|[1-2][0-9]|3[0-1]))|(02-(0[1-9]|[1-2][0-9]))|((0[469]|11)-(0[1-9]|[1-2][0-9]|30)))$/) {
    return 1;
  }
  return 0;
}

sub days_ago {
  my $d=shift // confess "I need a date here.";
  my $ago=shift // confess "I need an integer here.";
  my ($year,$month,$day) = &split_date($d);
  ($year,$month,$day) = &Date::Calc::Add_Delta_Days($year,$month,$day,-$ago);
  if(length($month)==1) {
    $month="0$month";
  }
  if(length($day)==1) {
    $day="0$day";
  }
  my $date="$year-$month-$day";
  return $date;
}

sub days_in_the_last_years {
  my $years_ago=shift // confess "I need a number here.";
  my $today=&today();
  my $year=substr($today,0,4);
  my $rest=substr($today,4);
  my $year_ago=$year-$years_ago;
  my $days=&diff_dates($year_ago.$rest,$today);
  return $days;
}




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