#!/bin/bash
#
# copy-daily-note
# John Simpson <jms1@jms1.net> 2024-07-01
#
# Copy the current date's Obsidian "Daily Note" to a file outside the vault.
# This is designed to be called from the "Shell commands" Obsidian plugin,
# in response to a "File content modified" event.
#
# https://jms1.info/obsidian/copy-daily.html
#
###############################################################################
#
# The MIT License (MIT)
#
# Copyright (C) 2024 John Simpson
#
# Permission is hereby granted, free of charge, to any person obtaining a
# copy of this software and associated documentation files (the "Software"),
# to deal in the Software without restriction, including without limitation
# the rights to use, copy, modify, merge, publish, distribute, sublicense,
# and/or sell copies of the Software, and to permit persons to whom the
# Software is furnished to do so, subject to the following conditions:
#
# The above copyright notice and this permission notice shall be included in
# all copies or substantial portions of the Software.
#
# THE SOFTWARE IS PROVIDED “AS IS”, WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
# IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
# FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
# THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
# LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
# FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
# DEALINGS IN THE SOFTWARE.
#
###############################################################################

########################################
# Default configuration values

CHECKSUM_PROGRAM="sha256sum"
DATE_FORMAT=""
LOG_IGNORED=false
LOG_FILE=""
INCLUDE_LINK=true

###############################################################################
#
# Simple logging function
# - if $LOG_FILE is defined, send output there with a timestamp
# - otherwise send to STDERR, which becomes an on-screen notification

function logit {
    MSG="${*:-}"

    if [[ -n "$LOG_FILE" ]]
    then
        NOW="$( date '+%Y-%m-%dT%H:%M:%S%z' )"
        echo "$NOW $MSG" >> "$LOG_FILE"
    else
        echo "$MSG" 1>&2
    fi
}

###############################################################################
#
# Find the root directory of the Obsidian Vault containing a file
# - start from the directory containing the file and walk "up" until we
#   find a directory which *contains* a '.obsidian' directory

function find_vault {
    ########################################
    # Make sure the file exists. (This also means that
    # all of its parent directories exist.)

    FILE="${1:-}"

    if [[ -z "$FILE" ]]
    then
        logit "ERROR: find_vault() called with no filename"
        exit 1
    fi

    if [[ ! -f "$FILE" ]]
    then
        logit "ERROR: '$FILE' file does not exist"
        exit 1
    fi

    ########################################
    # Start with the directory containing the file, and walk "up" until
    # we find a directory which contains a '.obsidian' directory.

    DIR="${FILE%/*}"
    while [[ -n "${DIR}" ]]
    do
        ########################################
        # Is this directory the root of a vault?

        if [[ -d "${DIR}/.obsidian" ]]
        then
            echo "$DIR"
            return
        fi

        ########################################
        # No, try its parent directory

        if [[ "$DIR" =~ / ]]
        then
            DIR="${DIR%/*}"

            if [[ -n "$DIR" ]]
            then
                continue
            fi
        fi

        ########################################
        # Couldn't find a parent directory, we're not in a vault

        logit "ERROR: could not find vault from '$FILE'"
        exit 1
    done
}

###############################################################################
#
# Extract a value from a JSON file.
#
# This will use 'jq' if it's available, and 'sed' if not. Using 'sed'
# *appears* to be working for what this script needs, but you shouldn't
# trust this as a general purpose JSON parser.

function get_json_value {
    ########################################
    # Read parameters

    FILE="${1:-}"
    KEY="${2:-}"

    if [[ -z "$FILE" ]]
    then
        logit "ERROR: get_json_value(): no filename specified"
        exit 1
    fi

    if [[ -z "$KEY" ]]
    then
        logit "ERROR: get_json_value(): no JSON key specified"
        exit 1
    fi

    ########################################
    # Run the appropriate command

    if type -t jq >/dev/null
    then
        RV="$( jq -r -M ".$KEY" "$FILE" )"
    else
        RV="$( sed -E -n "/.*\"$KEY\":/{s/.*\"$KEY\"[[:space:]]*:[[:space:]]*\"(.+)\".*/\1/p;}" "$FILE" )"
    fi

    ########################################
    # Return the value, without a trailing newline

    echo -n "$RV"
}

###############################################################################
# Convert a date format string from the "moment.js" library's weird format,
# to the standard "strftime()" format used by the "date" command (and almost
# every other program for the past 40+ years).
#
# Note that not all tags can be converted, because some of the specifiers in
# the "moment.js" library refer to things that I doubt people would use, or
# because strftime() doesn't support them. Please let me know if any other
# tags are needed, if I *can* add them I will.

# The script will try to read the "Daily notes" plugin's "Date format"
# configuration value, and convert it to a string which can be used with the
# 'date' command. If you're using a date format where this conversion doesn't
# work, you can use the '-d' option to specify the format by hand.
#
# Library used by the "Daily notes" plugin:
#   https://momentjs.com/docs/#/displaying/format/
# Library used by the 'date' command:
#   https://www.man7.org/linux/man-pages/man3/strftime.3.html
#
#   moment.js           strftime()      Notes
#   ----------------    -------------   -------------------------
#   "YYYY-MM-DD"        "%Y-%m-%d"      "Daily notes" plugin's default format
#   "YYYY-MM-DD ddd"    "%Y-%m-%d %a"   The format I use in my vaults



function fix_date_format {
    RV="$( echo "${1:-YYYY-MM-DD}" | perl -pe '
        s/(?<![%Y])YYYY(?!Y)/%Y/   ;
        s/(?<![%Y])YY(?!Y)/%y/     ;
        s/(?<![%Y])Y(?!Y)/%Y/      ;

        s/(?<![%M])MMMM(?!M)/%m/   ;
        s/(?<![%M])MMM(?!M)/%b/    ;
        s/(?<![%M])MM(?!M)/%m/     ;

        s/(?<![%D])DDDD(?!D)/%j/   ;
        s/(?<![%D])DD(?!D)/%d/     ;

        s/(?<![%d])dddd(?!d)/%A/   ;
        s/(?<![%d])ddd(?!d)/%a/    ;
    ' )"

    echo -n "$RV"
}

###############################################################################
###############################################################################
###############################################################################
#
# Parse the command line

while getopts ':hc:d:il:n' OPT
do
    case $OPT in
        h)  usage
            ;;
        c)  CHECKSUM_PROGRAM="${OPTARG}"
            ;;
        d)  DATE_FORMAT="${OPTARG}"
            ;;
        i)  LOG_IGNORED=true
            ;;
        l)  LOG_FILE="${OPTARG}"
            ;;
        n)  INCLUDE_LINK=false
            ;;
        *)  echo "ERROR: invalid option '-${OPTARG}'"
            exit 1
            ;;
    esac
done

shift $(( OPTIND - 1 ))

########################################
# Get the filenames from the command line.

UPDATED_FILE="${1:-}"
OUTPUT_FILE="${2:-}"

if [[ -z "$UPDATED_FILE" ]]
then
    logit "ERROR: no updated filename specified (check command line)"
    exit 1
fi

if [[ -z "$OUTPUT_FILE" ]]
then
    logit "ERROR: no output filename specified (check command line)"
    exit 1
fi

########################################
# Make sure the source file exists and is readable.

if [[ ! -f "$UPDATED_FILE" ]]
then
    logit "ERROR: updated file '$UPDATED_FILE' does not exist."
    exit 1
fi

if [[ ! -r "$UPDATED_FILE" ]]
then
    logit "ERROR: updated file '$UPDATED_FILE' is not readable."
    exit 1
fi

########################################
# Make sure the output file's directory exists and is writable.

OUTPUT_DIR="${OUTPUT_FILE%/*}"

if [[ ! -d "${OUTPUT_DIR}" ]]
then
    logit "ERROR: output directory '${OUTPUT_DIR}' does not exist."
    exit 1
fi

if [[ ! -w "${OUTPUT_DIR}" ]]
then
    logit "ERROR: output directory '${OUTPUT_DIR}' is not writable."
    exit 1
fi

########################################
# Find the root of the vault containing that file.

VAULT="$( find_vault "${UPDATED_FILE}" )"

########################################
# Figure out what directory within the vault is used for Daily notes.

DAILY_FOLDER="$( sed -E -n '/.*"folder":/{s/.*"folder"[[:space:]]*:[[:space:]]*"(.+)".*/\1/p;}' \
    "${VAULT}/.obsidian/daily-notes.json" )"

if [[ -n "${DAILY_FOLDER}" ]]
then
    DAILY_FOLDER="${DAILY_FOLDER}/"
fi

########################################
# Figure out the date format used by the Daily notes plugin.

if [[ -z "$DATE_FORMAT" ]]
then
    DAILY_FORMAT="$( sed -E -n '/.*"format":/{s/.*"format"[[:space:]]*:[[:space:]]*"(.+)".*/\1/p;}' \
        "${VAULT}/.obsidian/daily-notes.json" )"
    DATE_FORMAT="$( fix_date_format "${DAILY_FORMAT}" )"
fi

###############################################################################
#
# If the file being updated is not today's Daily note, exit.

TODAY="$( date "+${DATE_FORMAT}" )"

if [[ "${UPDATED_FILE}" != "${VAULT}/${DAILY_FOLDER}${TODAY}.md" ]]
then
    if $LOG_IGNORED
    then
        logit "'${UPDATED_FILE}' ignored"
    fi
    exit 0
fi

########################################
# Figure out if the file in the shared drive needs to be copied or not.
# - If the checksum file exists
#   - and it contains today's filename
#     - and the checksum itself is correct
#       - then we don't need to copy the file

CHECKSUM_FILE="${OUTPUT_FILE}.checksum"

if [[ -f "$CHECKSUM_FILE" ]]
then
    if grep -q " ${UPDATED_FILE}\$" "${CHECKSUM_FILE}"
    then
        if "${CHECKSUM_PROGRAM}" --status -c "$CHECKSUM_FILE"
        then
            logit "copy-daily-note checksum is correct, no update needed"
            exit 0
        fi
    fi
fi

###############################################################################
#
# Copy the file

########################################
# Start with a header that tells the readers when the file was copied

QNOW="$( date '+%Y-%m-%d %H:%M:%S %Z' )"

if $INCLUDE_LINK
then
    COPIED="[Copied from Obsidian](https://jms1.info/obsidian/copy-daily.html)"
else
    COPIED="Copied from Obsidian"
fi

cat > "${OUTPUT_FILE}" <<EOF
# $TODAY
$COPIED \`$QNOW\`

---

EOF

########################################
# Add the original file

cat "${UPDATED_FILE}" >> "${OUTPUT_FILE}"

########################################
# Create/update the checksum file

#pushd "${UPDATED_FILE%/*}"
"${CHECKSUM_PROGRAM}" "${UPDATED_FILE}" > "${CHECKSUM_FILE}"
#popd

########################################
# Log what we did

logit "Updated ${OUTPUT_FILE}"