#!/usr/bin/env bash
#==============================================================#
#
# AUTHOR:
#     Bryan Jenks
#         - www.bryanjenks.xyz
#         - https://github.com/tallguyjenks/flash.sh
#
# SOURCE:
#     This file is based off of the one presented in this YouTube Video by nixcasts:
#         - https://www.youtube.com/watch?v=lX8jqo70r1I
#
# 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
    CARD_POOL_SIZE=10 # How large the pool size is for shuf to draw from
    SEARCH_DEPTH=999  # How many levels to recursively search for .csv's in .local/share/flash

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

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

# Remember User's Starting Directory
    PWD="$(pwd)"
# Where Decks Are Located for linux & mac
# Prefer XDG Configuration before hard coded file paths
    OS="$(uname)"
    case "$OS" in
        "Darwin") DIR="${XDG_DATA_HOME:-HOME/Library/Application Support}/flash" ;;
        "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
    COUNTER=0
# Success message of setup process
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
"
# 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}
"
# The example flashcard deck to be made
DECK_TEMPLATE="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"

# Define setup process in a function and create necessary files for user
setup(){\
    mkdir "$DIR" && \
    eval touch {"$EXAMPLE_DECK","$HIGH_SCORE","$REVIEW_LOG"} && \
    echo "$DECK_TEMPLATE" >> "$EXAMPLE_DECK" && \
    echo -e "$DIR_MADE_MSG" \
;}

# 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 RESPONSE
        case "$RESPONSE" in
            [QqNn]) exit ;;
            [Yy]) setup && exit ;;
            *) echo -e "invalid choice, please select either ${LGREEN}y${NC} or ${LRED}n${NC}" && exit ;;
        esac
fi

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

# 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" | wc -l)" = 0 ]; then
    echo -e "$NO_DECKS" && cd "$PWD" && exit
fi

# if highscore file was removed, remake it.
if [ ! -e "$HIGH_SCORE" ]; then
    touch "$HIGH_SCORE"
fi

# if reviewed file was removed, remake it.
if [ ! -e "$REVIEW_LOG" ]; then
    touch "$REVIEW_LOG"
fi

a_flag=''
b_flag=''

print_usage() {
  printf "\n${LCYAN}fla.sh --- Flash card system by Bryan Jenks${NC} ${LBLUE}<BryanJenks@protonmail.com>${NC}\n\n${YELLOW}${BOLD}Usage:${NC}\n\t${GREEN}flash -h:${NC} Print this help text\n\t${GREEN}flash -i:${NC} Print Information about the flashcard system\n\t${GREEN}flash -v:${NC} Print version Number\n\n"
}

while getopts 'hiv' flag; do
  case "${flag}" in
    h) print_usage && exit ;;
    i) a_flag='true' ;;
    v) b_flag='true' ;;
    *) print_usage && exit 1 ;;
  esac
done


# Show pretty FZF preview of decks using BAT
    DECK="$(find . -maxdepth "$SEARCH_DEPTH" -iname "*.csv" | fzf --preview='bat --theme="Solarized (dark)" --style=numbers --color=always {} | head -500')"

# If no deck is selected in fzf menu
# return user to start location
# and exit quietly
if [ -z "$DECK" ]; then
    cd "$PWD" && exit
fi

main(){
    IFS=$':'
    # shellcheck disable=SC2162
    read -a q <<< "$(sort "$DECK" -n --field-separator=: --key=4 | head -n "$CARD_POOL_SIZE"| shuf -n 1)"
    clear
    echo -e "${WHITEBG}          Fla.sh - Flash Cards In Your Terminal            ${NC}"
    echo -e "${ORANGE}${BOLD}Cards Reviewed:${BOLD}${NC}\t$COUNTER"
    echo -e "\t${ORANGE}${BOLD}High Score:${BOLD}${NC}\t$(cat "$HIGH_SCORE")"
    echo -e "\t${ORANGE}${BOLD}Avg review:${BOLD}${NC}\t$(awk '{ sum += $7; n++ } END { if (n > 0) print sum / n; }' "$REVIEW_LOG")"
    echo -e ""
    echo -e "${LGREY}Category:${NC}\n\t\t${q[0]}"
    echo -e "${LGREY}Question:${NC}\n\t\t${q[1]}"
    echo -e ""
    echo -e ""
    echo -e "${LGREY}Press [Enter] to continue...${NC}"
    # shellcheck disable=SC2162
    read -sn 1 NEXT
    while [ ! "$NEXT" = "" ] && [ ! "$NEXT" = q ] && [ ! "$NEXT" = Q ]; do
        # shellcheck disable=SC2162
        read -sn 1 NEXT
    done
    clear
    echo -e "${WHITEBG}          Fla.sh - Flash Cards In Your Terminal            ${NC}"
    echo -e "${ORANGE}${BOLD}Cards Reviewed:${BOLD}${NC}\t$COUNTER"
    echo -e "\t${ORANGE}${BOLD}High Score:${BOLD}${NC}\t$(cat "$HIGH_SCORE")"
    echo -e "\t${ORANGE}${BOLD}Avg review:${BOLD}${NC}\t$(awk '{ sum += $7; n++ } END { if (n > 0) print sum / n; }' "$REVIEW_LOG")"
    echo -e ""
    echo -e "${LGREY}Category:${NC}\n\t\t${q[0]}"
    echo -e "${LGREY}Question:${NC}\n\t\t${q[1]}"
    echo -e ""
    if [ "$NEXT" = q ] || [ "$NEXT" = Q ]; then
        add_usage_entry && cd "$PWD" && clear && exit
    fi
    echo -e "${LGREY}Answer:${NC}\n\t\t${q[2]}"
    echo -e ""
    echo -e "${WHITEBG}${WHITE}===========================================================${NC}"
    echo -e ""
    echo -e "${LGREY}How Difficult Was This Question?${NC}"
    echo -e ""
    echo -e "${LRED}Hard${NC} [1]   ${RED}Difficult${NC} [2]   ${YELLOW}Normal${NC} [3]   ${GREEN}Mild${NC} [4]   ${LGREEN}Easy${NC} [5]"
    echo -e ""
    echo -e "${LGREY}Select a number to continue, or${NC} ${LRED}Q${NC} ${LGREY}to quit...${NC}"
    # shellcheck disable=SC2162
    read -sn 1 DIFFICULTY_SCORE
    while [[ ! "$DIFFICULTY_SCORE" =~ [12345qQ] ]]; do
        # shellcheck disable=SC2162
        read -sn 1 DIFFICULTY_SCORE
    done
    if [ "$DIFFICULTY_SCORE" = q ] || [ "$DIFFICULTY_SCORE" = Q ]; then
        add_usage_entry && cd "$PWD" && clear && exit
    fi
    clear

    COUNTER="$((COUNTER+1))" # Increment count for card review count increment

    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 "s/${q[0]}:${q[1]}:${q[2]}:${q[3]}/${q[0]}:${q[1]}:${q[2]}:$NEW_ITEM_SCORE/g" "$DECK"
    # If no highscore currently set, set it.
    if [ -z "$(cat "$HIGH_SCORE")" ]; then
        echo "$COUNTER" > "$HIGH_SCORE"
    fi

    # If Cards Reviewed > Current High Score, Update
    if [ "$COUNTER" -gt "$(cat "$HIGH_SCORE")" ]; then
        echo "$COUNTER" > "$HIGH_SCORE"
    fi

}

add_usage_entry(){
    if [ ! "$COUNTER" = 0 ]; then
        # Create a New Entry
        TIME_STAMP=$(date --rfc-3339=seconds)
        REVIEWED_DECK="$(echo "$EXAMPLE_DECK" | awk -F/ '{print $7}')"
        printf -v ENTRY "TimeStamp: %s Deck: %s cardsReviewed: %s" "$TIME_STAMP" "$REVIEWED_DECK" "$COUNTER"
        echo "$ENTRY" >> "$REVIEW_LOG"
    fi
}

while true; do
        main
done