#!/bin/bash

set -euo pipefail
SCRIPT_NAME="$(basename "$0")"

# Arg1: OLD_YEAR
# Arg2: NEW_YEAR
# Arg3: File Path
replace_copyright() {
    local PATTERN="s|Copyright (c) 2010-${1}, Deusty, LLC|Copyright (c) 2010-${2}, Deusty, LLC|g"
    if [[ "$(uname -s)" = 'Darwin' ]]; then
        sed -i '' -e "${PATTERN}" "$3"
        return $?
    else
        sed -i -e "${PATTERN}" "$3"
        return $?
    fi
}

current_year() {
    date '+%Y'
    return $?
}

last_year() {
    date -v'-1y' '+%Y'
    return $?
}

# Arg1: Mode (full, usage_only). Defaults to 'full'.
print_usage() {
    echo "Usage: ${SCRIPT_NAME} [OLD_YEAR NEW_YEAR]"
    if [[ "${1:-full}" = 'full' ]]; then
        echo ''
        echo 'If called with OLD_YEAR and NEW_YEAR arguments, updates the copyright years from OLD_YEAR to NEW_YEAR.'
        echo 'If called with no arguments but OLD_YEAR and NEW_YEAR environment variables defined, updates from OLD_YEAR to NEW_YEAR.'
        echo 'If called with no arguments and OLD_YEAR and NEW_YEAR not being defined, updates from last year to the current year.'
        echo ''
        echo 'Examples:'
        echo "$ ${SCRIPT_NAME} 2016 2017                       # Updates from 2016 to 2017."
        echo "$ OLD_YEAR=2017 NEW_YEAR=2018 ${SCRIPT_NAME}     # Updates from 2017 to 2018."
        echo "$ ${SCRIPT_NAME}                                 # Updates from $(last_year) to $(current_year)."
    fi
}

OLD_YEAR=${OLD_YEAR:-$(last_year)}
NEW_YEAR=${NEW_YEAR:-$(current_year)}
if [[ $# -gt 0 ]]; then
    if [[ $# -eq 2 ]]; then
        OLD_YEAR="$1"
        NEW_YEAR="$2"
    elif [[ $# -eq 1 ]] && [[ $1 == '--help' ]] || [[ $1 == '-h' ]]; then
        print_usage 'full'
        exit 0
    else
        echo 'Specifying years via command line arguments requires two arguments (OLD_YEAR and NEW_YEAR)!'
        echo 'For more information use --help.'
        echo ''
        print_usage 'usage_only'
        exit 1
    fi
fi

# We need to export the function so that bash can call it from the find exec argument.
export -f replace_copyright

EXTENDED_REGEX_FLAG_POST_PATH='-regextype posix-extended'
EXTENDED_REGEX_FLAG_PRE_PATH=''
if [[ "$(uname -s)" = 'Darwin' ]]; then
    EXTENDED_REGEX_FLAG_PRE_PATH='-E'
    EXTENDED_REGEX_FLAG_POST_PATH=''
fi

pushd "$(dirname "$0")/../" > /dev/null
find ${EXTENDED_REGEX_FLAG_PRE_PATH} \
    . \
    ${EXTENDED_REGEX_FLAG_POST_PATH} \
    -regex '.*\.([hm]|swift|pch)' \
    -exec bash -c "replace_copyright \"${OLD_YEAR}\" \"${NEW_YEAR}\" \"{}\"" \;
replace_copyright "${OLD_YEAR}" "${NEW_YEAR}" './LICENSE'
popd > /dev/null

# Delete the function again
unset -f replace_copyright