update

#!/bin/bash
#-*- coding: utf-8 -*-
# Author: Andrew Quach
#
# Manage the schedule at http://sstctf.org

VERSION="1.1.2"

# Constants
declare -r html_file='index.php'
declare -ra tag_prefix=("Previous" "Next" "Future") # Schedule column
declare -ra tag_body=("Date" "DateLong" "Topic" "Leader" "Description" "Homework" "Download") # Schedule field
declare -ra tag_suffix=("Begin" "End") # Position of tag in HTML
declare -ra tag_format=("MM/DD/YY" "WEEKDAY MONTH DATE (TIME)" "1 line of text" "First Last" "2 lines of text" "1 line of text" "/downloads/MM-DD-YY") # Format for the fields
declare -r prompt=$(echo $'\n> ') # Prompt format
declare -r is_num='^[0-9]+$'

# Globals
user_values=
formatted_user_values=

# Format for complete tag: [PREFIX][BODY][SUFFIX]
# Possible Tags
	# 0  PreviousDate          NextDate         FutureDate
	# 1  PreviousDateLong      NextDateLong     FutureDateLog
	# 2  PreviousTopic         NextTopic        FutureTopic
	# 3  PreviousLeader        NextLeader       FutureLeader
	# 4  PreviousDescription   NextDescription  FutureDescription
	# 5  PreviousHomework      NextHomework     FutureHomework
	# 6  PreviousDownload      NextDownload     FutureDownload

# Functions

# USAGE: print_help
print_help() {
    
# Usage information
cat <<EOF
USAGE: ./update [0|1]
0: Automatic Mode
1: Manual Mode

Automatic mode shifts over the latest two dates.
It then replaces the latest date with user input.

Manual mode allows the user to place any field needed.
No shifting is done.
EOF

    exit

}

# USAGE: retrieve_info [TAG]
retrieve_info() {
    
    # Add the suffix to the tag
    local start=$1${tag_suffix[0]}
    local end=$1${tag_suffix[1]}

    # Echo the information between the tags
    # 1. GREP the information in the HTML File
    # 2. Use SED to cut out the tags
    echo $(grep -o "<!--$start-->.*<!--$end-->" "$html_file" | sed "s/\(<\!\-\-$start\-\->\|<\!\-\-$end\-\->\)//g")

}

# USAGE: replace_info [TAG] [REPLACEMENT_TEXT]
replace_info() {
    
    # Add the suffix to the tag
    local start=$1${tag_suffix[0]}
    local end=$1${tag_suffix[1]}

    # Escape out the replacement text
    local escaped_text=$(echo $2 | sed -e 's/[\/&]/\\&/g')

    # Replace the information between the tags
    # 1. Use SED to replace the information between the tags

	sed -E "s/(<\!\-\-$start\-\->)(.*)(<\!\-\-$end\-\->)/\1$escaped_text\3/" -i "$html_file"

}

# USAGE: get_user_input [PREFIX]
get_user_input() {
    
    # Get user input
    # Ignore fields 1 and 6 (DateLong and Download)
    # They can be deduced from field 0 (Date)

    # Loop through the code the number tags times
    for i in ${!tag_body[@]}; do
        if [[ ($i -ne 1) && ($i -ne 6) ]]; then
            read -p "What is the value of $1${tag_body[i]}? Note: The recommended format is \"${tag_format[i]}\". $prompt" user_values[i]
        fi
    done

    # Get already inputted date if user skipped field
    if [[ ${user_values[0]} == 'n' ]]; then
        user_values[0]=$(retrieve_info $1"Date")
    fi

    # Set fields 1 and 6 to the same value as field 0
    user_values[1]=${user_values[0]}
    user_values[6]=${user_values[0]}

}


# Usage: format_user_input
format_user_input() {

    # Format field 0 and 1 (Date and DateLong) using date
    formatted_user_values[0]=$(date --date="${user_values[0]}" "+%m/%d/%g")
    formatted_user_values[1]=$(date --date="${user_values[1]}" "+%A %B %d")" (2:15-3:30)"

    # Added the corresponding headers to fields 2-5
    formatted_user_values[2]="Topic: "${user_values[2]}
    formatted_user_values[3]="Leader: "${user_values[3]}
    formatted_user_values[4]="Description: "${user_values[4]}
    formatted_user_values[5]="Homework: "${user_values[5]}

    # Generate a directory (/downloads/currentdate) if it doesn't exist
    # Enable if on server with sudo
    if [[ $(id -u) -eq 0 ]] && [[ $(hostname -s) = "sstctf" ]]; then
        mkdir -p /var/www/html/downloads/"$(date --date="${user_values[0]}" "+%m-%d-%g")" 
    fi
    # Link to that directory
    formatted_user_values[6]="<a href=\"downloads/"$(date --date="${user_values[0]}" "+%m-%d-%g")"\">"

}   

# USAGE: main
main() {
    
    # Automated Mode
    case $1 in
        0)
            # Warning
            echo "This operation will shift the last two dates down."
            echo "This is irreversible."
            read -p "Type 1 to confirm the operation. Type anything else to stop. $prompt" verify

            if [[ $verify -ne 1 ]]; then
                exit;
            fi

            # Get user input
            get_user_input Future

            # Format user input
            format_user_input

            # Store old columns - "Next" and "Future"
            local old_next_values=
            local old_future_Values=
            for i in ${!tag_body[@]}; do
                old_next_values[i]=$(retrieve_info ${tag_prefix[1]}${tag_body[i]});
                old_future_values[i]=$(retrieve_info ${tag_prefix[2]}${tag_body[i]});
            done

            # Shift columns one down.
            # 1. Old Next -> Previous
            # 2. Old Future -> Next
            # 3. User input -> Future
            for i in ${!tag_body[@]}; do
                replace_info ${tag_prefix[0]}${tag_body[i]} "${old_next_values[i]}"
                replace_info ${tag_prefix[1]}${tag_body[i]} "${old_future_values[i]}"
                replace_info ${tag_prefix[2]}${tag_body[i]} "${formatted_user_values[i]}"
            done
            ;;

        # Control Mode
        1)
            # Description
            echo "This operation will allow you to edit a specific column."
            read -p "What column do you wish to edit? ${prompt}Type 0 for \"Past\"${prompt}Type 1 for \"Next\"${prompt}Type 2 for \"Future\"${prompt}" selection

            # Verify if the choice made is between 0-2
            if ! [[ ($selection -ge 0) && ($selection -le 2) && ($selection =~ $is_num ) ]]; then
                echo "Invalid input."
                exit;
            fi

            echo "Type 'n' to skip a field. The original value will remain."

            # Get user input
            get_user_input ${tag_prefix[selection]}

            # Format user input
            format_user_input

            # Replace columns with user input
            for i in ${!tag_body[@]}; do

                # Do not replace if field contains "n"
                if [[ ${user_values[i]} != "n" ]]; then
                    replace_info "${tag_prefix[selection]}${tag_body[i]}" "${formatted_user_values[i]}"
                fi
            done

            ;;
        esac

}

# PROGRAM START
if [[ $# -eq 1 ]] && [[ ($1 -ge 0) && ($1 -le 1) ]] && [[ $1 =~ $is_num ]]; then
        main $1
else
        print_help
fi