flash

#!/usr/bin/env bash
#==============================================================#
#
# AUTHOR:
#     Bryan Jenks
#         - www.bryanjenks.xyz
#         - https://github.com/tallguyjenks/flash.sh
#     Modified by Lucien Grondin
#         - https://github.com/grondilu/fla.sh
#
# SOURCE:
#     This file is based off of the one presented in this YouTube Video by nixcasts:
#         - https://www.youtube.com/watch?v=lX8jqo70r1I
#     Regarding ANSI escape sequences:
#         - https://gist.github.com/fnky/458719343aabd01cfb17a3a4f7296797
#
# PURPOSE:
#     To have a command line flash card tool with minimal code, plain text input and output
#
# VISION:
#     The goal i have for this script is a basic level emulation of ANKI to where i have a way to
#     keep track of a score for each item in each selected deck so that it can pick from a selection
#     of the lowest scoring items and shuf them to the user for reenforcement of active recall.
#
# DEPENDENCIES:
#     fzf - https://github.com/junegunn/fzf
#     bat - https://github.com/sharkdp/bat
#==============================================================#

# USER CUSTOMIZABLE VARIABLES
declare -i CARD_POOL_SIZE=10        ######## How large the pool size is for shuf to draw from
declare -i SEARCH_DEPTH=999         ######### How many levels to recursively search for .csv's in .local/share/flash
declare PREVIEWER='bat'          ########## What fzf previewer to use when searching through decks
declare CURR_DECK_DISPLAY="file" # Options are 'file' or 'path'

# ANSI FOREGROUND ESCAPE COLORS
declare    RED=$'\033[0;31m'
declare   LRED=$'\033[1;31m'
declare YELLOW=$'\033[1;33m'
declare  GREEN=$'\033[0;32m'
declare LGREEN=$'\033[1;32m'
declare  LBLUE=$'\033[1;34m'
declare   CYAN=$'\033[0;36m'
declare  LCYAN=$'\033[1;36m'
declare ORANGE=$'\033[0;33m'
declare  LGREY=$'\033[0;37m'
declare  WHITE=$'\033[1;37m'
declare     NC=$'\033[0m' # No Color

declare REVERSE=$'\033[7m'

# ANSI BACKGROUND ESCAPE COLORS
declare WHITEBG=$'\033[1;47m'
# FONT FORMAT EXCAPE CODES
declare BOLD=$'\e[1m'

print-usage() {
  cat <<-END_USAGE
	${LCYAN}fla.sh --- Flash card system by Bryan Jenks${NC} ${LBLUE}<BryanJenks@protonmail.com>${NC}
	
	${YELLOW}${BOLD}Usage:${NC}
	    ${GREEN}flash -h:${NC} Print this help text
	    ${GREEN}flash -i:${NC} Print Information about the flashcard system
	    ${GREEN}flash -v:${NC} Print version Number
	    ${GREEN}flash -p [BINARY]:${NC} Change the previewer when selecting decks.
	        Default: ${GREEN}bat${NC}
	        Supported: ${GREEN}bat${NC}, ${GREEN}cat${NC}
	END_USAGE
}

print-info() {
  cat <<-END_INFO
	This flash card system works via colon ${YELLOW}:${NC} separated ${YELLOW}.csv${NC} files
	
	with entries that look like this: ${LGREY}category:question:answer:0${NC}
	
	These ${YELLOW}.csv${NC} files should be stored in your
	
	    ${YELLOW}\$XDG_DATA_HOME/flash${NC}
	OR
	    ${YELLOW}~/.local/share/flash${NC} for Linux
	    ${YELLOW}~/Library/Application Support/flash${NC} for mac
	-------------------------------------------------------------------------------
	${LCYAN}Exiting:${NC}
	
	    You can exit the application at any time by pressing either ${RED}q${NC} or ${RED}Q${NC}
	
	${LCYAN}Usage:${NC}
	
	    You will first be prompted with a question and will need to press ${RED}[Enter]${NC}
	    to reveal the answer. Once the answer is revealed you will need to either
	    quit, or give a rating to how difficult the question was.
	
	${LCYAN}The Scoring System:${NC}
	
	    The last field in the ${YELLOW}.csv${NC} files is the current point score of the 'card'
	    Every time you rate a card the point score will either increase, decrease,
	    or stay the same. zero is the lowest value, and the upper limit is over
	    100 billion.
	
	    ${CYAN}Scoring Results:${NC}
	    	[${LRED}Hard${NC}]		-2 points
	    	[${RED}Difficult${NC}]	-1 point
	    	[${YELLOW}Normal${NC}]	No Change
	    	[${GREEN}Mild${NC}]		+1 point
	    	[${LGREEN}Easy${NC}]		+2 points
	
	    The cards with the lowest scores (you scored them as ${LRED}Hard${NC}/${RED}Difficult${NC}) are
	    sorted to the top, a pool of them are picked and from that pool 1 card is
	    randomly drawn. As you become more familair with the material and rate it
	    as easier, the point values will go up and the cards will appear less
	    frequently making room for those cards that are still difficult and have
	    lower point values.
	
	It is a good idea to start all cards off at ${YELLOW}0${NC} initially so that they all
	have an equal chance of being drawn initially.
	END_INFO
}

# Remember User's Starting Directory
# PWD="$(pwd)"  # not used?

# Where Decks Are Located for linux & mac
# Prefer XDG Configuration before hard coded file paths
case "$(uname)" in
  Darwin) DIR="${XDG_DATA_HOME:-$HOME/Library/Application Support}/flash" && alias shuf=gshuf ;;
  Linux) DIR="${XDG_DATA_HOME:-$HOME/.local/share}/flash" ;;
  *) DIR="${XDG_DATA_HOME:-$HOME/.local/share}/flash" ;;
esac

# Where the example deck will be placed and named
EXAMPLE_DECK="$DIR/deck.csv"
# Track High score
HIGH_SCORE="$DIR/.highscore"
# Track number of cards reviewed per session
REVIEW_LOG="$DIR/.reviews"
# Iterator for Count of cards reveiwed
declare -i COUNTER=0

# User has .local/share directory but no decks inside
NO_DECKS="
No decks were found, please make a new deck
using ${ORANGE}:${NC} as a delimiter in a ${ORANGE}.csv${NC} file in
the ${LRED}$DIR${NC} directory.

An example of a card:
${GREEN}Math:What is the square root of 4?:2:0${NC}
"

# Define setup process in a function and create necessary files for user
setup() {
  # Success message of setup process
  local -r DIR_MADE_MSG="
  Your ${LRED}$DIR${NC} directory has been made and
  your ${ORANGE}deck.csv${NC} file is ready for you to enter your flashcard data
  If you want to see information about ${ORANGE}fla.sh${NC} then use the option
  ${YELLOW}flash -i${NC}."
  if mkdir "$DIR"
  then
    if touch "$EXAMPLE_DECK" "$HIGH_SCORE" "$REVIEW_LOG"
    then
      if cat <<-END_TEMPLATE >> "$EXAMPLE_DECK"
	History:When was the declaration of independence signed?:1776:0
	Math:What is the square root of 4?:2:4
	Science:What is the charge on a proton?:Positive 1:2
	Philosophy:What was Socrates known as?:The Gadfly of Athens:0
	Programming:What is the typical starting index of an array?:0:5
	History:What did Abraham Lincoln typically keep in his hat?:Mail:0
	Math:What is the value of PI to 2 decimal places?:3.14:4
	Science:What is the charge on an electron?:Negative 1:3
	Programming:What does OOP stand for?:Object Oriented Programming:2
	History:What did Socrates drink to commit suicide?:Hemlock Tea:2
	Math:What is the general equation for the slope of a line?:y=mx+b:4
	Science:What is the charge on a neutron?:Neutral:1
	Programming:What is Vim?:God's Text Editor:999
	History:What were the British known by during the American Revolution?:The Redcoats:1
	Math:What is the value of this equation - log10(100)?:2:0
	Science:What are protons and neutrons made of?:quarks:5
	Programming:What does RAM stand for?:Random Access Memory:1
	History:What was the year 2000 also known as?:Y2K:0
	Math:What is the formula for the mean?:Sum/count:4
	Science:What is cold?:The absense of heat:3
	Programming:What languages are the worst?:Proprietary:999
	History:When did man land on the moon?:1969:4
	Math:10^3=?:1000:1
	Science:The _____ ______ Project mapped all of man's genes.:Human Genome:3
	Programming:What is the best computer to program on?:Thinkpad:999
	History:When was fla.sh created?:April 2020:999
	Math:What do you call a number only divisible by itself and 1?:Prime:0
	Science:What is the distance between the Earth and Sol called?:An Astronomical Unit (AU):1
	Programming:What is the best operating system?:Arch, because BTW i run Arch:999"
	END_TEMPLATE
        then echo -e "$DIR_MADE_MSG"
      fi
    fi
  fi
}

# Test if .local/share exists and wether to offer setup process
if [ ! -d "$DIR" ]
then
    echo -e "No ${LRED}$DIR${NC} directory, make it? ${LGREEN}Y${NC}/${LRED}N${NC}"
    # shellcheck disable=SC2162
    read 
    case "${REPLY,,}" in
    [qn]) return 0 ;;
    y) setup && return 0 ;;
    *) >&2 echo -e "invalid choice, please select either ${LGREEN}y${NC} or ${LRED}n${NC}" && exit 1 ;;
    esac
fi

# go to the flashcard decks directory
#cd "$DIR" || exit 1
pushd "$DIR"

# If there are no flashcard decks available return user to starting location
# while also displaying explanatory text of issue
if
  ! find . -maxdepth "$SEARCH_DEPTH" -iname "*.csv" -print -quit |
  read
then 
  >&2 echo "$NO_DECKS"
  return 1
fi

# if highscore file was removed, remake it.
[ -e "$HIGH_SCORE" ] || : touch "$HIGH_SCORE"

# if reviewed file was removed, remake it.
[ -e "$REVIEW_LOG" ] || : touch "$REVIEW_LOG"

process-args() {
  local OPTIND OPTARG o
  while getopts 'hivp:' o
  do
    echo "option $o"
      case "$o" in
        h) print-usage && return 0 ;;
        i) print-info && return 0 ;;
        v) echo -e "\n${YELLOW}fla.sh Current Version:${NC} ${RED}1.2${NC}\n" && return 0 ;;
        p) { [[ $(command -v "$OPTARG" 2>&1) ]] && PREVIEWER=$OPTARG; } ||
          >&2 echo "Unable to find previewer $OPTARG. Exiting..." &&
          return 1 ;;
        *) print-usage && return 1 ;;
      esac
  done
}

# Set some parameters for preview command used by FZF
while [ -z "$PREVIEWER_PARAMTERS" ]
do
    case "$PREVIEWER" in
    bat) PREVIEWER_PARAMTERS="--theme='Solarized (dark)' --style=numbers --color=always" ;;
    cat) PREVIEWER_PARAMTERS="-b" ;;
    *) echo -e "${RED}$PREVIEWER${NC} is not a valid previewer. Use '${GREEN}bat${NC}' or '${GREEN}cat${NC}'. Falling back on default...\n" &&
      read -r -s -p 'Press [Enter] to continue...' &&
      echo -e "\n" &&
      PREVIEWER='bat' ;;
    esac
done

# Show pretty FZF preview of decks using $PREVIEWER. Default: BAT
DECK="$(find . -maxdepth "$SEARCH_DEPTH" -iname "*.csv" | fzf --preview="$PREVIEWER $PREVIEWER_PARAMTERS {} | head -500")"

# Creating new entries in the log for the average score generation
add-usage-entry() {
    if [ ! "$COUNTER" = 0 ]
    then
        # Create a New Entry
        TIME_STAMP=$(date +"%Y%m%d %H:%M:%S")
        printf -v ENTRY "TimeStamp: %s Deck: %s cardsReviewed: %s" "$TIME_STAMP" "${DECK##*/}" "$COUNTER"
        echo "$ENTRY" >>"$REVIEW_LOG"
    fi
}

function center() {
  fmt -w59 <<<"$1" |
  while read -r
  do printf "%$(( (59 - ${#REPLY})/2 ))s%s\n" ' ' "$REPLY"
  done
}

# If no deck is selected in fzf menu
# return user to start location
# and exit quietly
[ -z "$DECK" ] && return 1

quiz() {

  clear

  # hiding cursor
  echo -e "\e[?25l"

  sort "$DECK" -n --field-separator=: --key=4 |
  {
    local -i PICK
    mapfile -t 
    echo "${MAPFILE[
      RANDOM%(${#MAPFILE[@]} < CARD_POOL_SIZE ? ${#MAPFILE[@]} : CARD_POOL_SIZE)
    ]}"
  } |
  {
    local -a q
    local -i DIFFICULTY_SCORE

    IFS=: read -r -a q

    cat <<-EOF
	$REVERSE$BOLD          Fla.sh - Flash Cards In Your Terminal            $BOLD$REVERSE
	${ORANGE}${BOLD}  Current Deck:${BOLD}${NC}	$(basename -s .csv "${DECK##*/}")
	${ORANGE}${BOLD}Cards Reviewed:${BOLD}${NC}	$COUNTER
	    ${ORANGE}${BOLD}High Score:${BOLD}${NC}	$(cat "$HIGH_SCORE")
	    ${ORANGE}${BOLD}Avg review:${BOLD}${NC}	$(awk '{ sum += $7; n++ } END { if (n > 0) print sum / n; }' "$REVIEW_LOG")
	
	${LGREY}Category:${NC} ${q[0]}
	___________________________________________________________
	
	EOF
        center "${q[1]}"

    echo -e "\n${LGREY}──────────────── Press [Enter] to continue ────────────────${NC}"

    while
      read -sn 1 < /dev/tty
      ! [[ "$REPLY" =~ ^[qQ]?$ ]]
    do :
    done
    echo -ne "\e[1F"

    [[ "${REPLY,}" = q ]] && add-usage-entry && exit 0

    cat <<-EOF
	___________________________________________________________
	
	$(center "${q[2]}")
	
	${REVERSE}===========================================================${REVERSE}
	
	${LGREY}How Difficult Was This Question?${NC}
	
	${LRED}[H]ard${NC}  ${RED}[D]ifficult${NC}  ${YELLOW}[N]ormal${NC}  ${GREEN}[M]ild${NC}  ${LGREEN}[E]asy${NC}
	
	${LGREY}Select a letter continue, or${NC} ${LRED}Q${NC} ${LGREY}to quit...${NC}"
	EOF


    local -Ari difficulty=([H]=0 [D]=1 [N]=2 [M]=3 [E]=4) 
    # shellcheck disable=SC2162
    while
      read -sn 1 </dev/tty
      [[ ! "${REPLY^}" =~ [12345QHDNME] ]]
    do :
    done
    [[ "${REPLY,}" = q ]] && add-usage-entry && exit 0

    if [[ "${REPLY^}" =~ [HDNME] ]]
    then DIFFICULTY_SCORE=${difficulty[${REPLY^}]}
    else DIFFICULTY_SCORE=REPLY
    fi

    # Increment count for card review count increment
    ((COUNTER++))

    local -i NEW_ITEM_SCORE
    if (( q[3] == 0 ))
    then
        NEW_ITEM_SCORE=0
        case "$DIFFICULTY_SCORE" in
        [123]) NEW_ITEM_SCORE=0 ;; #HARD DIFFICULTY & NORMAL
        4) NEW_ITEM_SCORE=1 ;; #MILD
        5) NEW_ITEM_SCORE=2 ;; #EASY
        *) NEW_ITEM_SCORE=0 ;; #INVALID
        esac
    elif (( q[3] == 1 ))
    then
        case "$DIFFICULTY_SCORE" in
        1) NEW_ITEM_SCORE=0 ;; #HARD
        2) NEW_ITEM_SCORE=0 ;; #DIFFICULT
        3) NEW_ITEM_SCORE=1 ;; #NORMAL
        4) NEW_ITEM_SCORE=2 ;; #MILD
        5) NEW_ITEM_SCORE=3 ;; #EASY
        *) NEW_ITEM_SCORE=1 ;; #INVALID
        esac
    else
        case "$DIFFICULTY_SCORE" in
        1) NEW_ITEM_SCORE="$((q[3] - 2))" ;; #HARD
        2) NEW_ITEM_SCORE="$((q[3] - 1))" ;; #DIFFICULTY
        3) NEW_ITEM_SCORE="${q[3]}"       ;; #NORMAL
        4) NEW_ITEM_SCORE="$((q[3] + 1))" ;; #MILD
        5) NEW_ITEM_SCORE="$((q[3] + 2))" ;; #EASY
        *) NEW_ITEM_SCORE="${q[3]}"       ;; #INVALID
        esac
    fi

    # Update item score for each flashcard item
    sed -i "$((PICK+1))s/:[^:]*$/:$NEW_ITEM_SCORE/" "$DECK"
    
    # If no highscore currently set, set it.
    [ -z "$(cat "$HIGH_SCORE")" ] && echo "$COUNTER" >"$HIGH_SCORE"

    local -i high_score
    read high_score < "$HIGH_SCORE"
    # If Cards Reviewed > Current High Score, Update
    ((COUNTER > high_score)) && echo "$COUNTER" >"$HIGH_SCORE"

  }

  # restoring cursor
  echo -e "\e[?25h\e[?47l"

}

#while true
#do main
#done