game2048

#!/bin/bash

declare -r SIZE=4

declare -r KEY_UP="w"
declare -r KEY_DOWN="s"
declare -r KEY_RIGHT="d"
declare -r KEY_LEFT="a"

declare -r BEST_SCORE_FILE="best-score.txt"

declare -i fixedTileIndex
declare -i floatTileIndex

declare -i score
declare -i bestScore
declare shifted
declare -a tiles
declare keepGoing=false

function writeBestScore() {
    if [[ -w $BEST_SCORE_FILE ]]; then
        if (( score > bestScore )); then
            echo "$score" > $BEST_SCORE_FILE
        fi
    fi
}

function readBestScore() {
    if [[ -r $BEST_SCORE_FILE ]]; then
        bestScore=$(cat $BEST_SCORE_FILE)
    else
        bestScore=0
    fi
}

function display() {
    local -i i
    local -i j
    local -i tileValue
    local generatedColor

    readBestScore

    echo -e "\e[1;1f\e[2J" # clear display
    echo -e "\e[31mScore: $score    Best: $bestScore"
    echo

    for (( i = 0; i < SIZE; i++ )); do
        for (( j = 0; j < SIZE; j++ )); do
            tileValue=${tiles[i * SIZE + j]}
            generatedColor="\e[3$(( (tileValue % 10) / 2 + 1 ))m"
            echo -n -e " $generatedColor" $tileValue " "
        done
        echo
    done
}

function placeRandomTile() {
    local -a freeTiles
    local -i i
    local randomTile

    for (( i = 0; i < (SIZE * SIZE); i++ )); do
        if (( tiles[i] == 0 )); then
            freeTiles[${#freeTiles[*]}]=$i
        fi
    done

    randomTile=${freeTiles[$(( $RANDOM % ${#freeTiles[@]} ))]}

    if (( $RANDOM % 100 <= 90 )); then
        tiles[$randomTile]=2
    else
        tiles[$randomTile]=4
    fi
}

function incOrDecFixedTileIndex() {
    local -l direction=$1
    local -l incOrDec=$2

    if [[ x"$direction" = x"h" ]]; then
        if [[ x"$incOrDec" = x"inc"  ]]; then
            ((fixedTileIndex++))
        else
            ((fixedTileIndex--))
        fi
    else
        if [[ x"$incOrDec" = x"inc"  ]]; then
            ((fixedTileIndex += SIZE))
        else
            ((fixedTileIndex -= SIZE))
        fi
    fi
}

function shiftTile() {
    local -l direction=$1
    local -l incOrDec=$2

    local -i fixedTile=${tiles[$fixedTileIndex]}
    local -i floatTile=${tiles[$floatTileIndex]}
    local -i sum

    if [[ $floatTile -eq 0 ]]; then
        return
    fi

    tiles[$floatTileIndex]=0

    if [[ $fixedTile -eq 0 ]]; then
        tiles[$fixedTileIndex]=$floatTile
    elif [[ $floatTile -eq $fixedTile ]]; then
        sum=$((floatTile + fixedTile))
        tiles[$fixedTileIndex]=$sum
        incOrDecFixedTileIndex $direction $incOrDec
        (( score += sum))
        writeBestScore
    else
        incOrDecFixedTileIndex $direction $incOrDec
        tiles[$fixedTileIndex]=$floatTile
    fi
    shifted=true
}

function shiftToLeft() {
    for (( i = 0; i < SIZE; i++ )); do
        fixedTileIndex=$((i * SIZE))
        for (( j = 1; j < SIZE; j++ )); do
            floatTileIndex=$((i * SIZE + j))
            shiftTile "h" "inc"
        done
    done
}

function shiftToRight() {
    for (( i = 0; i < SIZE; i++ )); do
        fixedTileIndex=$((i * SIZE + (SIZE - 1)))
        for (( j = SIZE - 2; j >= 0; j-- )); do
            floatTileIndex=$((i * SIZE + j))
            shiftTile "h" "dec"
        done
    done
}

function shiftToTop() {
    for (( j = 0; j < SIZE; j++ )); do
        fixedTileIndex=$((j))
        for (( i = 1; i < SIZE; i++ )); do
            floatTileIndex=$((i * SIZE + j))
            shiftTile "v" "inc"
        done
    done
}

function shiftToBottom() {
    for (( j = 0; j < SIZE; j++ )); do
        fixedTileIndex=$((SIZE * (SIZE - 1) + j))
        for (( i = SIZE - 2; i >=0 ; i-- )); do
            floatTileIndex=$((i * SIZE + j))
            shiftTile "v" "dec"
        done
    done
}

function action() {
    shifted=false
    local -l key

    read -n 1 key
    case $key in
        $KEY_UP ) shiftToTop ;;
        $KEY_DOWN ) shiftToBottom ;;
        $KEY_LEFT ) shiftToLeft ;;
        $KEY_RIGHT ) shiftToRight ;;
    esac
}

function askWantContinue() {
    local -l key

    echo "You win!"
    echo "k) Keep going"
    echo "r) Try again!"
    read -n 1 key

    case $key in
        "r" ) newGame ;;
        * ) keepGoing="true";;
    esac
}

function isYouWin() {
    if [[ ($score -eq 2048) && ($keepGoing = "false") ]]; then
        return 0;
    else
        return 1;
    fi
}

function newGame() {
    score=0
    shifted=false
    tiles=(
        0 0 0 0
        0 0 0 0
        0 0 0 0
        0 0 0 0
    )

    placeRandomTile; placeRandomTile;
    display
}

function main() {
    stty -echo

    newGame

    while [[ true ]]; do
        action
        if [[ $shifted = "true" ]]; then
            placeRandomTile
        fi
        display

        if isYouWin; then
            askWantContinue
            display
        fi
    done
}

main