#!/usr/bin/env bash

#important variables
declare -ia board # array that keeps track of game status
declare -i pieces # number of pieces present on board
declare -i score=0 # score variable
declare -i flag_skip # flag that prevents doing more than one operation on
# single field in one step
declare -i moves # stores number of possible moves to determine if player lost
# the game
declare ESC=$'\e' # escape byte
declare header="Bash 2048 v1.1 (https://github.com/mydzor/bash2048)"

declare -i start_time=$(date +%s)

#default config
declare -i board_size=4
declare -i target=2048
declare -i reload_flag=0
declare config_dir="$HOME/.bash2048"

#for colorizing numbers
declare -a colors
colors[2]=33 # yellow text
colors[4]=32 # green text
colors[8]=34 # blue text
colors[16]=36 # cyan text
colors[32]=35 # purple text
colors[64]="33m\033[7" # yellow background
colors[128]="32m\033[7" # green background
colors[256]="34m\033[7" # blue background
colors[512]="36m\033[7" # cyan background
colors[1024]="35m\033[7" # purple background
colors[2048]="31m\033[7" # red background (won with default target)

exec 3>/dev/null # no logging by default

trap "end_game 0 1" INT #handle INT signal

#simplified replacement of seq command
function _seq {
local cur=1
local max
local inc=1
case $# in
1) let max=$1;;
2) let cur=$1
let max=$2;;
3) let cur=$1
let inc=$2
let max=$3;;
esac
while test $max -ge $cur; do
printf "$cur "
let cur+=inc
done
}

# print currect status of the game, last added pieces are marked red
function print_board {
clear
printf "$header pieces=$pieces target=$target score=$score\n"
printf "Board status:\n" >&3
printf "\n"
printf '/------'
for l in $(_seq 1 $index_max); do
printf '+------'
done
printf '\\\n'
for l in $(_seq 0 $index_max); do
printf '|'
for m in $(_seq 0 $index_max); do
if let ${board[l*$board_size+m]}; then
if let '(last_added==(l*board_size+m))|(first_round==(l*board_size+m))'; then
printf '\033[1m\033[31m %4d \033[0m|' ${board[l*$board_size+m]}
else
printf "\033[1m\033[${colors[${board[l*$board_size+m]}]}m %4d\033[0m |" ${board[l*$board_size+m]}
fi
printf " %4d |" ${board[l*$board_size+m]} >&3
else
printf ' |'
printf ' |' >&3
fi
done
let l==$index_max || {
printf '\n|------'
for l in $(_seq 1 $index_max); do
printf '+------'
done
printf '|\n'
printf '\n' >&3
}
done
printf '\n\\------'
for l in $(_seq 1 $index_max); do
printf '+------'
done
printf '/\n'
}

# Generate new piece on the board
# inputs:
# $board - original state of the game board
# $pieces - original number of pieces
# outputs:
# $board - new state of the game board
# $pieces - new number of pieces
function generate_piece {
while true; do
let pos=RANDOM%fields_total
let board[$pos] || {
let value=RANDOM%10?2:4
board[$pos]=$value
last_added=$pos
printf "Generated new piece with value $value at position [$pos]\n" >&3
break;
}
done
let pieces++
}

# perform push operation between two pieces
# inputs:
# $1 - push position, for horizontal push this is row, for vertical column
# $2 - recipient piece, this will hold result if moving or joining
# $3 - originator piece, after moving or joining this will be left empty
# $4 - direction of push, can be either "up", "down", "left" or "right"
# $5 - if anything is passed, do not perform the push, only update number
# of valid moves
# $board - original state of the game board
# outputs:
# $change - indicates if the board was changed this round
# $flag_skip - indicates that recipient piece cannot be modified further
# $board - new state of the game board
function push_pieces {
case $4 in
"up")
let "first=$2*$board_size+$1"
let "second=($2+$3)*$board_size+$1"
;;
"down")
let "first=(index_max-$2)*$board_size+$1"
let "second=(index_max-$2-$3)*$board_size+$1"
;;
"left")
let "first=$1*$board_size+$2"
let "second=$1*$board_size+($2+$3)"
;;
"right")
let "first=$1*$board_size+(index_max-$2)"
let "second=$1*$board_size+(index_max-$2-$3)"
;;
esac
let ${board[$first]} || {
let ${board[$second]} && {
if test -z $5; then
board[$first]=${board[$second]}
let board[$second]=0
let change=1
printf "move piece with value ${board[$first]} from [$second] to [$first]\n" >&3
else
let moves++
fi
return
}
return
}
let ${board[$second]} && let flag_skip=1
let "${board[$first]}==${board[second]}" && {
if test -z $5; then
let board[$first]*=2
let "board[$first]==$target" && end_game 1
let board[$second]=0
let pieces-=1
let change=1
let score+=${board[$first]}
printf "joined piece from [$second] with [$first], new value=${board[$first]}\n" >&3
else
let moves++
fi
}
}

function apply_push {
printf "\n\ninput: $1 key\n" >&3
for i in $(_seq 0 $index_max); do
for j in $(_seq 0 $index_max); do
flag_skip=0
let increment_max=index_max-j
for k in $(_seq 1 $increment_max); do
let flag_skip && break
push_pieces $i $j $k $1 $2
done
done
done
}

function check_moves {
let moves=0
apply_push up fake
apply_push down fake
apply_push left fake
apply_push right fake
}

function key_react {
let change=0
read -d '' -sn 1
test "$REPLY" = "$ESC" && {
read -d '' -sn 1 -t1
test "$REPLY" = "[" && {
read -d '' -sn 1 -t1
case $REPLY in
A) apply_push up;;
B) apply_push down;;
C) apply_push right;;
D) apply_push left;;
esac
}
} || {
case $REPLY in
k) apply_push up;;
j) apply_push down;;
l) apply_push right;;
h) apply_push left;;
esac
}
}

function save_game {
rm -rf "$config_dir"
mkdir "$config_dir"
echo "${board[@]}" > "$config_dir/board"
echo "$board_size" > "$config_dir/board_size"
echo "$pieces" > "$config_dir/pieces"
echo "$target" > "$config_dir/target"
# echo "$log_file" > "$config_dir/log_file"
echo "$score" > "$config_dir/score"
echo "$first_round" > "$config_dir/first_round"
}

function reload_game {
printf "Loading saved game...\n" >&3

if test ! -d "$config_dir"; then
return
fi
board