#!/bin/bash
# Notes manager for the command line

NOTES_VER="0.1a"
NOTES_DIR="$HOME/.notes"

# Initialize with the default editor
[ -z "$EDITOR" ] && EDITOR="/usr/bin/vim"

notes_init() {
    # Check if the notes folder exists, if not, create it
    if [ ! -d $NOTES_DIR ]
    then
        echo -n "Creating notes folder..."
        mkdir -p $NOTES_DIR
        cd $NOTES_DIR
        echo "done."

        git init .
    else
        echo "Notes has already been initialized."
    fi
}

make_title() {
    echo "$*" | sed 's/[^A-Za-z0-9_-]\+/-/g' | \
    sed 'y/ABCDEFGHIJKLMNOPQRSTUVWXYZ/abcdefghijklmnopqrstuvwxyz/'
}

title_to_name() {
    note_file=$NOTES_DIR/$(make_title $note_arg)
}

check_arg() {
    if [ -z "$note_arg" ]
    then
        echo "Must specify a note title!"
        exit
    fi
}

note_exists() {
    [[ -f "$note_file" ]]
}

check_md5() {
    if [[ "$note_old_md5" == "$note_new_md5" ]]
    then
        echo "No changes to '$note_arg'"

        if [[ ! -z "$1" ]]
        then
            rm -f $1
        fi

        exit
    fi
}

check_dir() {
    if [[ ! -d "$NOTES_DIR" ]]
    then
        echo "Notes not initialized. Run init first!"
        exit
    fi
}

help_cmd() {
    echo '
Notes Manager for the Command Line
==================================

This is a bash script that lets you take notes which are maintained in a
Git repository. You can run this script by typing the following command
at the command line:

Usage: note <command> <arguments>

Commands
--------

    Command     Usage
    -------     -----
    new         Follow this with the note name to create a new note
    edit        Follow this with the note name to edit an existing note
    delete      Follow this with the note name to delete a note
    list        Prints the list of available notes
    history     Displays the note history
    init        Run this the very first time to set up the folders
    help        Prints this help message
    version     Prints the version information
'
}

version_info() {
    echo "Notes Manager version $NOTES_VER"
}

parse_args() {
    note_cmd=$1
    shift
    note_arg="$*"

    case "$note_cmd" in
    "help")
        help_cmd
        ;;

    "new")
        check_dir
        check_arg
        title_to_name

        if note_exists
        then
            echo "Note '$note_arg' already exists! Use edit instead."
            exit
        fi

        echo "$note_arg" > $note_file
        note_old_md5=$(md5sum $note_file)

        $EDITOR $note_file

        note_new_title=$(head -1 $note_file)
        note_new_md5=$(md5sum $note_file)
        note_new_file=$(make_title $note_new_title)
        check_md5 $note_file

        cd $NOTES_DIR
        gitfile=$(basename $note_new_file)

        git add $gitfile
        git commit -m "Create note '$note_new_title'"
        echo "Created note '$note_new_title'"

        ;;

    "edit")
        check_dir
        check_arg
        title_to_name
        if ! note_exists
        then
            echo "Cannot find note '$note_arg'!"
            exit
        fi

        note_old_title=$(head -1 $note_file)
        note_old_md5=$(md5sum $note_file)

        $EDITOR $note_file

        note_new_title=$(head -1 $note_file)
        note_new_md5=$(md5sum $note_file)

        check_md5

        cd $NOTES_DIR
        gitfile=$(basename $note_file)
        commit_msg="Update note '$note_new_title'"
        if [[ "$note_old_title" != "$note_new_title" ]]
        then
            note_new_file=$(make_title $note_new_title)
            
            git mv $gitfile $note_new_file
            git add $note_new_file
            commit_msg="$commit_msg. Rename from '$note_old_title'"
        else
            git add $gitfile
        fi

        git commit -m "$commit_msg"
        echo "Updated note '$note_new_title'"
        ;;

    "del" | "delete")
        check_dir
        check_arg
        title_to_name
        if ! note_exists
        then
            echo "Cannot find note '$note_arg'!"
            exit
        fi

        cd $NOTES_DIR
        gitfile=$(basename $note_file)
        git rm $gitfile
        git commit -m "Delete note '$note_arg'"
        echo "Deleted note '$note_arg'"
        ;;

    "hist"|"history")
        check_dir
        cd $NOTES_DIR
        git log --pretty=format:'%ai - %s' -- $note_arg
        ;;
    
    "init")
        notes_init
        ;;
    
    "list")
        check_dir
        cd $NOTES_DIR
        ls -1 $note_arg
        ;;
    
    "ver" | "version")
        version_info
        ;;

    *)
        echo "Unrecognized command '$note_cmd'. Use help."
        ;;
    esac
}

if [[ $# -lt 1 ]]
then
    echo "Usage: note <command> <arguments>"
    echo "Type 'note help' for detailed help"
else
    parse_args $*
fi