#!/bin/bash
#==========================================================
# Simple Note System, v2.0a9
# Copyright 2016, Xenese Labs/Sicron-Perion XNF
#==========================================================

# Prevent freak accidents involving the root directory
if [ -z "$HOME" ]; then HOME=/home/"$(whoami)"; fi

# Store files and locations
readonly PROD_STR="Simple Note System"
readonly VER_STR="v2.0a9"
readonly ROOT_DIR="$HOME"/.config/sns
readonly NOTES_DIR="$ROOT_DIR"/notes
readonly TMP_DIR="$ROOT_DIR"/tmp
readonly CONFIG_FILE="$ROOT_DIR/sns.conf"

#Color codes for error reporting
readonly RED_COLOR='\033[1;31m'
readonly RESET_COLOR='\033[0m'

#Print the program header to stdout
printf "%s\n" "$PROD_STR"
printf "%s\n" "------------------"

# Section: Functions
function init_store {

if [ ! -d "$ROOT_DIR" ]; then mkdir -p "$ROOT_DIR"; WILL_INIT="TRUE"; fi
if [ ! -d "$TMP_DIR"  ]; then mkdir -p "$TMP_DIR" ; WILL_INIT="TRUE"; fi


cat > "$CONFIG_FILE" << EOF
# This file contains directives for the Simple Note System.

EXT=note                # File extension to use (for listing notes)

#EDITOR=                # Preferred Editor:
                        # If you would like to specify a different editor for
                        # sns to use, you may do so here.

ENCRYPTION="FALSE"      # Main Encryption Toggle:
                        # WARNING: ANY PREVIOUSLY UNENCRYPTED NOTES WILL BE LOST
                        # Change this to TRUE to enable encryption.

PUBKEY=""               # Public Key
                        # Encryption is done using GPG. You must enter your
                        # public key's identifier here.
EOF

chmod 600 "$CONFIG_FILE"

printf "  - %s\n" "Rewrote Default Configuration"

if [ "$WILL_INIT" == "TRUE" ]; then
    printf "  - %s\n" "Environment initialized in $ROOT_DIR"
else
    printf "  - %s\n" "Store already initialized."
fi
}
function verify_store {

    ETC_DIR=$(dirname "$CONFIG_FILE")

    STORE_DIRS=("$ROOT_DIR" "$NOTES_DIR" "$TMP_DIR" "$ETC_DIR")
    for DIR in "${STORE_DIRS[@]}"; do
        if [ ! -d "$DIR" ]; then
            mkdir -p "$DIR"
        fi
    done
}
function help {
    printf "\n%s" "usage: sns [-cedp] NAME NOTEBOOK SECTION"
    printf "\n%s" "       sns [-l] NOTEBOOK"
    printf "\n%s" "       sns [-hi ]"

    printf "\n%s" "  -c | --create : Create note"
    printf "\n%s" "  -d | --delete : Delete note"
    printf "\n%s" "  -e | --edit   : Open note for editing"
    printf "\n%s" "  -h | --help   : Display this message"
    printf "\n%s" "  -p | --print  : Print note to console"
    printf "\n%s" "  -l | --list   : List all notes in NOTEBOOK"
    printf "\n%s" "  -i | --init   : Write default config and initalize SNS store"
    printf "\n"
}
function p_header(){
    printf "TITLE: %s\nDATE: %s\n" "$NAME" "$(date)"
}
function encrypt(){
# This function, given a recipient, $PUBKEY; a file to encrypt, $TMP_NOTE; and an
# output file, $NOTE, will encrypt $TMP_NOTE to $NOTE against $PUBKEY's private
# GPG key.

    gpg -r "$PUBKEY" -o "$NOTE" -e "$TMP_NOTE"

}

function decrypt(){
# This function, given a file to decrypt, will attempt to decrypt the file
# against the specified recipient's private key, and print the result to
# stdout.
    gpg -d "$NOTE"
}
function create(){
    # Depends : p_header
    # Requires: $NOTE, $NOTE_DIR,
    # Optional: $ENCRYPTION, $SESSION_ID, $TMP_DIR encrypt
    # Given a valid setup, create writes the standard note header as specified
    # by p_header, to $NOTE.

    # Refuse to overwrite a note
     if [ -e "$NOTES_DIR/$NOTE" ]; then
        >&2 printf "  $RED_COLOR!$RESET_COLOR %s\n\t%s\n"\
          "Note already exists"\
          "Hint: use -e to edit the note."
         exit 200
    fi

    # If the note's notebook/section does not exist,
    # create the appropriate folders.
    mkdir -p "$NOTES_DIR"/"$(dirname "$NOTE")"

    # Write the standard note header
     if [ "$ENCRYPTION" == "TRUE" ]; then
        TMP_NOTE="$TMP_DIR"/"$SESSION_ID"
        p_header > "$TMP_NOTE"
        encrypt
     else
        p_header > "$NOTES_DIR/$NOTE"
     fi
    # Make sure the note exists, and inform the user of the result.
     if [ -e "$NOTES_DIR/$NOTE" ]; then
        printf "  - %s\n" "Created note: ${NOTE%.*}"
     else
        >&2 printf "  $RED_COLOR!$RESET_COLOR%s\n"\
         "Something went wrong, and the note was not created."
     fi
}
function delete(){
    # Requires: $NOTE, $NOTE_DIR
    # Given a valid $NOTE, delete removes $NOTE from sns.

     if [ -e "$NOTES_DIR/$NOTE" ]; then
        rm "$NOTES_DIR/$NOTE"
        printf "  - %s\n" "Deleted note: ${NOTE%.*}."
     else
        >&2 printf "  $RED_COLOR!$RESET_COLOR %s\n" "Note ${NOTE%.*} does not exist."
     fi
}
function edit(){
# Requires: $EDITOR, $NOTE
# Optional: $ENCRYPTION, $TMP_DIR, $SESSION_ID, decrypt, encrypt

# Verify an editor was specified
if [ -z "$EDITOR" ]; then
    >&2 printf "  $RED_COLOR!$RESET_COLOR %s\n"\
     "No editor specified in environment."
    exit
# Verify the note exists
elif [ ! -r "$NOTE" ]; then
    >&2 printf "  $RED_COLOR!$RESET_COLOR %s\n"\
     "Note cannot be opened for editing."
    exit 40;
fi

# If encryption is enabled, decrypt $NOTE to a temp file, otherwise
# operate on the note directly.
if [ "$ENCRYPTION" == "TRUE" ]; then
    cp "$NOTE" "$NOTE".bk #Insurance
    TMP_NOTE="$TMP_DIR/$SESSION_ID"
    decrypt > "$TMP_NOTE"
else
    TMP_NOTE="$NOTE";
fi

# Write an ammendment header
if [ -z "$CREATE" ]; then
    printf "\n %s\n" "edit - $(date)" >> "$TMP_NOTE"
    printf "\n %s\n" "===================================" >> "$TMP_NOTE"
fi

# Call the editor
printf "  - %s\n" "editing ${NOTE%.*}"
"$EDITOR" "$TMP_NOTE"

# If the file was previously decrypted, encrypt it back
if [ "$ENCRYPTION" == "TRUE" ]; then
    rm "$NOTE"
    encrypt;
    if [ ! -r "$NOTE" ]; then
        >&2 printf "  $RED_COLOR!$RESET_COLOR %s\n" "error: note was not saved."
        cp "$NOTE.bk" "$NOTE"
    else
        rm "$NOTE.bk";
    fi
fi

}
function print(){
# Given an existing file, $NOTE, print prints the contents of $NOTE to stdout.

if [ -r "$NOTE" ]; then
    if [ "$ENCRYPTION" == "TRUE" ]; then decrypt #to stdout
    else cat "$NOTE"; fi
else
    >&2 printf "  $RED_COLOR!$RESET_COLOR %s\n\t%s\n"\
     "Note cannot be found."
    exit 205 #ERR_NOTE_NO_READ
fi
}
function list(){
    # This function, given a folder, $NOTE, will list the contents of $NOTE.
    ls "$NOTE"
}
# End Section: Functions
#==============================================================================
# Stage 1: Read Configuration / Verify Integrity
#==============================================================================

if [ -r "$CONFIG_FILE" ]; then
    source "$CONFIG_FILE"
    verify_store
else
    >&2 printf "  $RED_COLOR!$RESET_COLOR %s\n\t%s\n"\
     "Configuration note found. Please run sns -i."
     exit 5 #ERR_NO_STORE
fi

if [ "$ENCRYPTION" == "TRUE" ]; then
    if   [ ! -r "$(which gpg)" ]; then
        >&2 printf "  $RED_COLOR!$RESET_COLOR %s\n\t%s\n"\
            "Encryption was specified, but GPG is not installed."
        exit 100
    elif [ -z "$PUBKEY" ]; then
        >&2 printf "  $RED_COLOR!$RESET_COLOR %s\n\t%s\n"\
         "No GPG recipient was provided in $CONFIG_FILE. "
        exit 110
    fi
fi
#==============================================================================
# Stage 2: Argument Parsing
#==============================================================================
NOTE=""
if [ -z "$1" ]; then help; exit 20
else
    for ARG in "$@"; do
        case "$ARG" in
            -c|--create)
                CREATE="TRUE"
                OP="TRUE"
                ;;
            -d|--delete)
                DELETE="TRUE"
                OP="TRUE"
                ;;
            -e|--edit)
                EDIT="TRUE"
                OP="TRUE"
                ;;
            -ce|-ec)
                CREATE="TRUE"
                EDIT="TRUE"
                OP="TRUE"
                ;;
            -l|--list)
                LIST="TRUE"
                OP="TRUE"
                ;;
            -p|--print)
                PRINT="TRUE"
                OP="TRUE"
                ;;
            -h|--help)
                help
                exit 0
                ;;
            -i|--init-store)
                init_store
                exit 0
                ;;
            *)
                NOTE="$ARG"
                break;
                ;;
        esac
    done
fi
#==============================================================================
# Section: Actions / Stage 3
#==============================================================================
# Default behavior
# If no operation was specified, print help and exit on ERR_NO_OP
    if [ "$OP" != "TRUE" ]; then
        help; exit 20
    fi
# All options not requiring a note to be specified have been dealt
# with; if one isn't specified, exit on ERR_NO_NOTE.
if [ -z "$NOTE" ]; then
    printf "  $RED_COLOR!$RESET_COLOR %s\n" "No note specified."
    exit 30
fi

if [ "$ENCRYPTION" == "TRUE" ]; then
    SESSION_ID="$RANDOM" #SESSION_ID later becomes the temporary filename
    readonly NOTE="$NOTE.$EXT.gpg"
else
    readonly NOTE="$NOTE.$EXT"
fi

if [ "$LIST"   == "TRUE" ]; then list  ; exit 0; fi
if [ "$PRINT"  == "TRUE" ]; then print ; exit 0; fi
if [ "$DELETE" == "TRUE" ]; then delete; exit 0; fi
if [ "$CREATE" == "TRUE" ]; then create; fi
if [ "$EDIT"   == "TRUE" ]; then edit  ; fi
#==============================================================================
# End Section: Actions / Stage 3
#==============================================================================