# shellcheck shell=dash
# vim: ft=sh

# substitute replaces all occurances of one string with another in the provided
# file, writing to the specified output file.
substitute() {
    local input="$1"
    local output="$2"

    shift 2

    # TODO: real parsing
    local search="$1"
    local replace="$2"

        #-v RS="$(printf "\0")" \
    awk \
        -v srch="$search" \
        -v repl="$replace" \
        -v RS="" \
        -v ORS="" \
        '{ gsub(srch, repl, $0); print $0 }' \
        < "$input" > "$output"
}

# substituteInPlace works like substitute but operates in-place on the provided
# file
substituteInPlace() {
    local fpath="$1"
    shift

    local tmpfile
    tmpfile="$(mktemp)"
    
    if ! substitute "$fpath" "$tmpfile" "$@"; then
        rm "$tmpfile"
        return $?
    fi

    # Overwrite now that we've succeeded
    mv "$tmpfile" "$fpath"
}

# Shell-quotes an arbitrary string.
#
# From: http://www.etalabs.net/sh_tricks.html
#
#     This function simply replaces every instance of «'» (single quote) within
#     the string with «'\''» (single quote, backslash, single quote, single
#     quote), then puts single quotes at the beginning and end of the string.
#     Since the only character whose meaning is special within single quotes is
#     the single quote character itself, this is totally safe. Trailing
#     newlines are handled correctly, and the single quote at the end doubles
#     as a safety character to prevent command substitution from clobbering the
#     trailing newlines, should one want to do something like:
#         quoted=$(quote "$var")
quote() {
    printf "%s\n" "$1" | sed "s/'/'\\\\''/g;1s/^/'/;\$s/\$/'/"
}


# Returns whether or not a string matches a glob; similar to the bash [[ test,
# but portable.
fnmatch() {
    # We explicitly want this to act as a glob
    # shellcheck disable=SC2254
    case "$2" in
        $1) return 0 ;;
        *)  return 1 ;;
    esac
}

# Portable equivalent to GNU's `date +"%s"`
#
# From: http://www.etalabs.net/sh_tricks.html
epochseconds() {
    # This is horrible, but... it tells 'date' to generate a string that
    # contains shell math to generate the actual epoch date.
    #
    # TODO(andrew-d): break down and verify the math here
    echo $(( $(TZ=GMT0 date +"((%Y-1600)*365+(%Y-1600)/4-(%Y-1600)/100+(%Y-1600)/400+1%j-1000-135140)*86400+(1%H-100)*3600+(1%M-100)*60+(1%S-100)") ))
}