pcal

#!/bin/bash

BREAKS=(-61 9 38 199 426 686 756 818 1111 1181 1210 1635 2060 2097 2192 2262 2324 2394 2456 3178)
DAY_NAMES_FA=(Sh Ye Do Se Ch Pa Jo)
declare -A DAY_NAMES=([Sh]=0 [Ye]=1 [Do]=2 [Se]=3 [Ch]=4 [Pa]=5 [Jo]=6)
declare -A DAY_NAMES_EN=([Sat]=Sh [Sun]=Ye [Mon]=Do [Tue]=Se [Wed]=Ch [Thu]=Pa [Fri]=Jo)
MONTH_NAMES=(Farvardin Ordibehesht Khordad Tir Mordad Shahrivar Mehr Aban Azar Dey Bahman Esfand)

exit_error() {
  >&2 echo "$1"
  exit 1
}

to_jalaali() {
  local gy=$1
  local gm=$2
  local gd=$3

  echo $(d2j $(g2d $gy $gm $gd))
}

to_gregorian() {
  local jy=$1
  local jm=$2
  local jd=$3

  echo $(format_output $(d2g $(j2d $jy $jm $jd)))
}

g2d() {
  local gy=$1
  local gm=$2
  local gd=$3
  local d=$(( (gy + (gm - 8) / 6 + 100100) * 1461 / 4 + (153 * ((gm + 9) % 12) + 2) / 5 + gd - 34840408 ))

  echo $(( d - ((gy + 100100 + (gm - 8) / 6) / 100) * 3 / 4 + 752 ))
}

d2g() {
  local jdn=$1
  local j=$((4 * jdn + 139361631))
  j=$(( j + (3 * ((4 * jdn + 183187720) / 146097) / 4) * 4 - 3908 ))
  local i=$(( ((j % 1461) / 4) * 5 + 308 ))
  local gd=$(( ((i % 153) / 5) + 1 ))
  local gm=$(( (i / 153) % 12 + 1 ))
  local gy=$(( j / 1461 - 100100 + (8 - gm) / 6 ))

  echo "$gy $gm $gd"
}

jal_cal() {
  local jy=$1
  local without_leap=$2
  local bl=${#BREAKS[@]}
  local gy=$((jy + 621))
  local leapj=-14
  local jp=${BREAKS[0]}

  if [[ $jy -lt $jp || $jy -ge ${BREAKS[$((bl - 1))]} ]]; then
    exit_error "Invalid Jalaali year $jy"
  fi

  for ((i = 1; i < bl; i++)); do
    local jm=${BREAKS[$i]}
    local jump=$((jm - jp))

    if [[ $jy -lt $jm ]]; then
      break
    fi

    leapj=$(( leapj + (jump / 33) * 8 + (jump % 33) / 4  ))
    jp=$jm
  done

  local n=$((jy - jp))
  leapj=$(( leapj + (n / 33) * 8 + ((n % 33) + 3) / 4 ))

  if [[ $((jump % 33)) -eq 4 && $((jump - n)) -eq 4 ]]; then
    leapj=$((leapj + 1))
  fi

  leapg=$(( gy / 4 - ((gy / 100) + 1) * 3 / 4 - 150 ))
  march=$((20 + leapj - leapg))

  if [[ $without_leap == "false" ]]; then
    if [[ $((jump - n)) -lt 6 ]]; then
      n=$(( n - jump + ((jump + 4) / 33) * 33 ))
    fi

    local leap=$(( ((n + 1) % 33 - 1) % 4 ))

    if [[ leap -eq -1 ]]; then
      leap=4
    fi
  fi

  echo "$leap $gy $march"
}

d2j() {
  local jdn=$1
  local gy=$(d2g $jdn)
  gy=${gy%% *}
  local jy=$((gy - 621))
  local r="$(jal_cal $jy 'false')"
  local jdn1f=$(g2d $gy 3 ${r##* })
  local k=$((jdn - jdn1f))

  if [[ $k -ge 0 ]]; then
    if [[ $k -le 185 ]]; then
      local jm=$((1 + k / 31))
      local jd=$((k % 31 + 1))

      echo "$(format_output $jy $jm $jd)"
      return 0
    else
      k=$((k - 186))
    fi
  else
    jy=$((jy - 1))
    k=$((k + 179))

    if [[ ${r%% *} -eq 1 ]]; then
      k=$((k + 1))
    fi
  fi

  local jm=$((7 + k / 30))
  local jd=$((k % 30 + 1))

  echo "$(format_output $jy $jm $jd)"
}

j2d() {
  local jy=$1
  local jm=$2
  local jd=$3
  local r=$(jal_cal $jy "true")
  local gy=${r#* }
  gy=${gy% *}
  local g2d_res=$(g2d $gy 3 ${r##* })

  echo $(( g2d_res + (jm - 1) * 31 - (jm / 7) * (jm - 7) + jd - 1 ))

}

zero_pad() {
  local num=$1

  [[ $num -lt 10 ]] && num="0$num"

  echo "$num"
}

format_output() {
  local jy=$1
  local jm=$(zero_pad $2)
  local jd=$(zero_pad $3)
  local odel=${OPTION_ODEL--}

  echo "$jy$odel$jm$odel$jd"
}

parse_input() {
  local input_date=$1
  local idel=${OPTION_IDEL:--}
  local y=${input_date%%$idel*}
  local m=${input_date%$idel*}
  m=${m#*$idel}
  local d=${input_date##*$idel}

  echo "$((10#$y)) $((10#$m)) $((10#$d))"
}

is_leap_jalaali_year() {
  [[ $(jal_cal_leap $(current_persian_year)) -eq 0 ]] && echo "true" && return 0
  echo "false"
}

jal_cal_leap() {
  local jy=$1
  local bl=${#BREAKS[@]}
  local jp=${BREAKS[0]}

  if [[ $jy -lt $jp || $jy -ge ${BREAKS[$((bl - 1))]} ]]; then
    echo "Invalid Jalali year $jy"
    exit 0
  fi

  for ((i = 1; i < bl; i++)); do
    local jm=${BREAKS[$i]}
    local jump=$((jm - jp))
    [[ $jy -lt $jm ]] && break
    jp=$jm
  done

  local n=$((jy - jp))
  [[ $((jump - n)) -lt 6 ]] && n=$(( n - jump + ((jump + 4) / 33) * 33 ))
  local leap=$(( ((n + 1) % 33 - 1) % 4 ))
  [[ $leap -eq -1 ]] && leap=4
  set -x
  echo $leap
}

jalaali_month_length() {
  local jm=$1

  [[ $jm -le 6 ]] && echo "31" && return 0
  [[ $jm -le 11 ]] && echo "30" && return 0
  [[ $(is_leap_jalaali_year) == "true" ]] && echo "30" && return 0
  echo "29"
}

print_current_month() {
  local index=$(first_day_of_month)
  local counter=0
  local day=1
  local current_month=$(current_persian_month)
  local month_length=$(jalaali_month_length $current_month)
  local fcolor='\e[39m'
  local bcolor='\e[49m'
  local dfcolor='\e[39m'
  local dbcolor='\e[49m'
  local current_day=$(current_persian_day)
  local current_month_name=${MONTH_NAMES[$((current_month - 1))]}
  local month_name_length=${#current_month_name}
  local month_pad=$(((21 + month_name_length) / 2))

  printf '%12s\n' $(current_persian_year)
  printf "%${month_pad}s\n" $current_month_name
  echo ${DAY_NAMES_FA[@]}

  for ((i = 0; i < 6; i++)); do
    for ((j = 0; j < 7; j++)); do
      if [[ $counter -lt $index || $day -gt $month_length ]]; then
        printf "   "
      else
        if [[ $j -eq 6 ]]; then
          fcolor='\e[31m'
        elif [[ $j -eq 5 ]]; then
          fcolor='\e[95m'
        else
          fcolor=$dfcolor
        fi

        if [[ $day -eq  $current_day ]]; then
          bcolor='\e[42m'
        else
          bcolor=$dbcolor
        fi

        printf "$bcolor$fcolor%02d$dfcolor$dbcolor " $day
        day=$((day + 1))
      fi
      counter=$((counter + 1))
    done
    echo ""
  done
  echo ""
}



find_en_day_name() {
  local first_day_number=$1
  local current_seconds=$(printf '%(%s)T' -1)
  local first_date_seconds=$(( current_seconds - (first_day_number - 1) * 86400 ))
  echo "$(printf '%(%a)T' $first_date_seconds)"
}

first_day_of_month() {
  local current=$(current_persian_date)
  local first_day_number=$((10#${current##*-}))

  echo ${DAY_NAMES[${DAY_NAMES_EN[$(find_en_day_name $first_day_number)]}]}
}

current_persian_date() {
  local current_g=$(printf '%(%F)T' -1)
  local current_j=$(to_jalaali $(parse_input $current_g))
  echo "$current_j"
}

current_persian_day() {
  local current=$(current_persian_date)
  local current_day=${current##*-}
  echo $((10#$current_day))
}

current_persian_month() {
  local current=$(current_persian_date)
  local current_month=${current%-*}
  current_month=${current_month#*-}
  echo $((10#$current_month))
}

current_persian_year() {
  local current=$(current_persian_date)
  local current_year=${current%%-*}
  echo $((10#$current_year))
}

print_help() {
  echo "Usage: pcal [d idelim] [D odelim]"
  echo "  Convert Gregorian calendar date to Persian calendar date."
  echo ""
  echo "  Reads a Gregorian calendar date from standard input and prints "
  echo "  its corresponding Persian calendar date to standard output."
  echo ""
  echo "  Options:"
  echo "    -h          display this help and exit"
  echo "    -d idelim   use IDELIM instead of - for input date delimiter"
  echo "    -D Odelim   use ODELIM instead of - for output date delimiter"
  echo "    -g          convert Persian calendar date to Gregorian calendar date"
  echo "    -m          display current Persian month in calendar"
  echo "    -t          print current Persian date"
}

main() {
  local input_data
  local gregorian
  local must_exit=1

  while getopts ":hd:D:gmt" opt; do
    case ${opt} in
      d)
        OPTION_IDEL=$OPTARG
        ;;
      D)
        OPTION_ODEL=$OPTARG
        ;;
    esac
  done

  OPTIND=1

  while getopts ":hd:D:gmt" opt; do
    case ${opt} in
      h)
        print_help
        exit 0
        ;;
      d)
        OPTION_IDEL=$OPTARG
        ;;
      D)
        OPTION_ODEL=$OPTARG
        ;;
      g)
        gregorian=1
        ;;
      t)
        current_persian_date
        exit
        ;;
      m)
        print_current_month
        exit
        ;;
      \?)
        echo "Invalid Option: -$OPTARG" 1>&2
        exit 1
        ;;
      :)
        echo "Invalid Option: -$OPTARG requires an argument" 1>&2
        exit 1
        ;;
    esac
  done
  shift $((OPTIND -1))

  read input_data

  if [[ $gregorian -eq 1 ]]; then
    to_gregorian $(parse_input $input_data)
  else
    to_jalaali $(parse_input $input_data)
  fi
}

main "$@"