#!/bin/bash
set -o nounset
set -o errexit

function _echo
{
    echo -e "$1"
}

function _echoB
{
    _echo "\033[1m$1\033[0m"
}

red=$(tput setaf 1)
green=$(tput setaf 2)
yellow=$(tput setaf 3)
normal=$(tput sgr0)

function _help
{
    _echo ""
    _echoB "A command line PERT calculator for quick estimates."
    _echo "Comma separated task list in the form \"one,1,2,12 two,4,5,9 three,2,3,6\", where whitespace separates tasks."
    _echo ""
    _echoB "Usage:"
    _echo "\tpert [name,optimistic,realistic,pessimistic]"
    _echo ""
    _echoB "Example:"
    _echo "\tpert one,1,3,4"
    _echo "\tpert one,10,15,20 two,5,7,10"
    _echo "\tpert \"one,1,2,3\" \"two,15,17,20\""
    _echo ""
}

scale=2
function _calc
{
    _echo "scale=$scale; $@" | bc -l | sed 's/^\./0./'
}

width=88
function _divider
{
    divider=------------------------------
    divider=" +"$divider$divider$divider"+"
    printf "%$width.${width}s+\n" "$divider"
}

readonly format=" | %-12s |${green}%11s${normal} |%10s |${red}%12s${normal} |%9s |${yellow}%9s${normal} |%9s |\n"
function _header
{
    _echo ""
    _echoB "Task"
    _echo ""
    _divider
    printf "$format" "#" "optimistic" "realistic" "pessimistic" "duration" "risk" "variance"
    _divider
}


function pert_table
{
    _header

    counter=0
    total_estimate=0
    total_standard_deviation=0
    total_variance=0
    time=("$@")
    for var in "${time[@]}"; do

        # counter iterator
        counter=$[$counter +1]

        # split values
        IFS=',' read -ra ADDR <<< "$var"
o="0"
        if [ -n "${ADDR[0]-}" ]; then
            t=${ADDR[0]}
        fi

        # optimistic value
        o="0"
        if [ -n "${ADDR[1]-}" ]; then
            o=${ADDR[1]}
        fi

        # realistic value
        r="0"
        if [ -n "${ADDR[2]-}" ]; then
            r=${ADDR[2]}
        fi

        # pessimistic value
        p="0"
        if [ -n "${ADDR[3]-}" ]; then
            p=${ADDR[3]}
        fi

        # check values
        if [ -z "$o" ] || [ -z "$r" ] || [ -z "$p" ]; then
            printf "$format" "$counter. bad input" $t $o $r $p
        else

            # pert estimate
            pert_estimate=$(_calc "($o+4*$r+$p)/6")
            total_estimate=$(_calc "$total_estimate + $pert_estimate")

            # standard deviation
            standard_deviation=$(_calc "($p-$o)/6")
            total_standard_deviation=$(_calc "$total_standard_deviation + $standard_deviation")

            # variance
            variance=$(_calc "$standard_deviation * $standard_deviation")
            total_variance=$(_calc "$total_variance + $variance")

            # row
            printf "$format" "$counter."$t $o $r $p $pert_estimate $standard_deviation $variance
        fi

    done

    _divider

    if [[ $total_estimate > 0 ]]; then

        # footer summary
        printf "$format" "summary" "-" "-" "-" $total_estimate $total_standard_deviation $total_variance
        _divider

        _echo ""
        _echoB "Three point estimates"
        _echo ""

        width=42
        tpeformat=" | %-13s |%11s |%10s |\n"

        _divider
        printf "$tpeformat" "confidence"
        _divider
        printf "$tpeformat" "1 Sigma - 68%" $(_calc "$total_estimate - $total_standard_deviation") $(_calc "$total_estimate + $total_standard_deviation")
        printf "$tpeformat" "2 Sigma - 95%" $(_calc "$total_estimate - 2 * $total_standard_deviation") $(_calc "$total_estimate + 2 * $total_standard_deviation")
        printf "$tpeformat" "3 Sigma - 99%" $(_calc "$total_estimate - 3 * $total_standard_deviation") $(_calc "$total_estimate + 3 * $total_standard_deviation")
        _divider

    fi

    _echo ""
}


# main
if [ ! -t 0 ];then
    time=$(cat -)
    pert_table ${time[@]}
else
    if [ $# -eq 0 ]; then
        _help
        exit 1
    fi

    case "$1" in
      *help|*h)
        _help
        exit 1
        ;;
      *)

        pert_table $@
        exit 0
        ;;
    esac
fi