#!/bin/sh

[[ -e /opt/bssdtk/core ]] && . /opt/bssdtk/core || {
        echo Requires bssdtk to be installed.
        exit 1
}

requireOnce colors

DATAFILE="${HOME}/.todo-list"
DATE_FORMAT="%Y-%m-%d %H:%M"

MINUTE=60
HOUR=$(( $MINUTE * 60))
DAY=$(( $HOUR * 24))
WEEK=$(( $DAY * 7 ))
MONTH=$(( $WEEK * 4 ))
YEAR=$(( $WEEK * 52 ))

function SaveNewToDo () {
    [[ -e "${DATAFILE}.temp" ]] && mv "${DATAFILE}.temp" "${DATAFILE}"
}

function Plural () {
    [[ "$3" != "1" ]] && echo "$3 $2" || echo "$3 $1"
}

function ToSeconds () {
    if [[ "$(uname)" == "Darwin" ]] ; then
        # Mac Version
        date -j -f "%a %b %d %T %Z %Y" "$1" "+%s"
    else
        date --date "`date`" "+%s"
    fi;
}

function FromSeconds () {
    if [[ "$(uname)" == "Darwin" ]] ; then
        # Mac Version
        date -r "$1" +"$DATE_FORMAT"
    else
        # Linux Version
        date -d @"$1" +"$DATE_FORMAT"
    fi
}

function DayName () {
    if [[ "$(uname)" == "Darwin" ]] ; then
        # Mac Version
        local when=$(date -r "$1")
    else
        # Linux Version
        local when=$(date -d @"$1")
    fi
    local name=$(echo $when | cut -d " " -f 1)
    local day=$(echo $when | cut -d " " -f 3)
    case day in
        1|21|31) local suffix=st
        ;;
        2|22) local suffix=nd
        ;;
        3|23) local suffix=rd
        ;;
        *) local suffix=th
    esac
    echo $name the ${day}${suffix}
}

function SetRemainingText () {
    if [[ "$status" == "C" ]] ; then
        remaining="$(FromSeconds $due)"
        remaining_text=Completed
    else
        remaining=$(( $due - $(ToSeconds "$(date)") ))
        remaining_text="$remaining"
        if [[ $remaining -lt 0 ]] ; then
            remaining_text=Overdue
        elif [[ $remaining -lt $DAY ]] ; then
            remaining_text="Today by $(echo $(FromSeconds $due) | cut -d ' ' -f 2)"
        elif [[ $remaining -lt $WEEK ]] ; then
            remaining_text="In $(Plural day days $(( $remaining / $DAY )) ) on $(DayName $due)"
        else
            remaining_text="In $(Plural week weeks $(( $remaining / $WEEK ))) on $(echo $(FromSeconds $due) | cut -d ' ' -f 1)"
        fi
    fi
}

function SetPriorityText () {
    case $priority in
        L)
            priorty_text=Low
        ;;
        H)
            priorty_text=High
        ;;
        *)
            priorty_text=Medium
    esac
}

function DoToDo () {
    local task=$1
    shift
    index=0
    while read -r line ; do
        [[ "$(echo $line)" == "" ]] && continue
        status=$(echo $line|cut -d , -f 1| tr "[:lower:]" "[:upper:]")
        priority=$(echo $line|cut -d , -f 2| tr "[:lower:]" "[:upper:]")
        SetPriorityText
        added=$(echo $line|cut -d , -f 3)
        due=$(echo $line|cut -d , -f 4)
        SetRemainingText
        message=$(echo $line|cut -d , -f 5-)
        $task
        (( index++ ))
    done<"$DATAFILE"
}

function ShowItem () {
    echoNoBreak "#$index ($priorty_text), ${remaining_text}, ${message}"
}

function SaveItem () {
    echo "$status,$priority,$added,$due,$message">>"${DATAFILE}.temp"
}

function ShowAllOfType () {
    local class=$1
    shift
    if [[ "$class" == "*" ]] || [[ "${class//$status/}" != "$class" ]] ; then
        ShowItem
    fi
}

function ShowIncomplete () {
    ShowAllOfType I
}

function PushToDo () {
    if [[ "$number" == "*" ]] || [[ "$number" == "$index" ]] ; then
        case $(echo $delayinc | tr "[:upper:]" "[:lower:]") in
            day|days)
                local pushby=$(( $delayby * $DAY ))
            ;;
            week|weeks)
                local pushby=$(( $delayby * $WEEK ))
            ;;
            month|months)
                local pushby=$(( $delayby * $MONTH ))
            ;;
            year|years)
                local pushby=$(( $delayby * $YEAR))
            ;;
            *)
                local pushby=$(( $delayby * $HOUR ))
        esac
        setColor red
        ShowItem
        due=$(( $due + $pushby ))
        setColor green
        SetRemainingText
        ShowItem
        setColor default
    fi
    SaveItem
}

function MarkComplete () {
    if [[ "$number" == "*" ]] || [[ "$number" == "$index" ]] ; then
        setColor green
        now=$(ToSeconds "$(date)")
        due=$now
        status=C
        SetPriorityText
        SetRemainingText
        ShowItem
        setColor default
    fi
    SaveItem
}

while [[ "${1}" != "" ]] ; do
    case "${1}" in
        help)
            echoNoBreak "Usage: ${0##*/} option [parameters...]"
            echoNoBreak
            echoNoBreak "  help          show help"
            echoNoBreak "  add M         add a new todo with Message"
            echoNoBreak "  done N        todo Number is complete"
            echoNoBreak "  push N T [F]  push Number is out by Time [hour,day,week..]"
            echoNoBreak "  list          list todo items."
            echoNoBreak
            exit 0
        ;;
        add|new)
            message="$2"
            shift
            while [[ "$2" != "" ]] ; do
                message="$message $2"
                shift
            done
            now=$(ToSeconds "$(date)")
            message="I,M,$now,$(($now + $WEEK)),$message"
            echo "$message">>"$DATAFILE"
            echoNoBreak "Added new item: \`$(echo $message | cut -d , -f 5-)'"
            echoNoBreak "Due by $(FromSeconds $(echo $message | cut -d , -f 4))"
        ;;
        done|finish|finished|complete|completed)
            number="$2"
            shift
            DoToDo MarkComplete
            SaveNewToDo
        ;;
        push|delay)
            number="$2"
            shift
            delayinc="days"
            delayby="$2"
            shift
            if [[ "$2" != "" ]] ; then
                delayinc="$2"
                shift
            fi
            DoToDo PushToDo
            SaveNewToDo
        ;;
        list)
            [[ ! -e "$DATAFILE" ]] && {
                echo "No To-Do list present."
                exit 0
            }
            DoToDo ShowIncomplete
        ;;
        *)
        echo "Error: \`${1}' is an invalid option."
        exit 1
    esac

    shift

done