update_readme

#!/bin/bash

set -euo pipefail

ROOT="$(git rev-parse --show-toplevel)"

rdm:usage() {
    cat <<EOF
Usage: $(basename "$0") FILE

Updates a given markdown file by injecting the output of \`go run main.go --help\` into it.

Arguments:
  FILE        Markdown file to update.
EOF
}

# Updates a given markdown file by running a number of injectors on it.
# Args:
#  $1: Markdown file to update.
rdm:update() {
    if [[ $# -ne 1 ]]; then
        rdm:usage
        exit 1
    fi

    local file="${1:?Specify file}"
    local tmp_file
    tmp_file="$(mktemp --suffix='.md')"
    cp "$file" "$tmp_file"

    rdm:inject_usage "$tmp_file"

    mv "$tmp_file" "$file"
}

# Injects the output of `go run main.go --help` into the provided markdown file.
# Args:
#  $1: Markdown file to update.
rdm:inject_usage() {
    local begin_marker='<!-- BEGIN CFDDNS_USAGE -->'
    local end_marker='<!-- END CFDDNS_USAGE -->'

    local file="${1:?Specify file}"
    local tmp_file
    tmp_file="$(mktemp --suffix='.usage.md')"

    sed -n "1,/$begin_marker/p" "$file" >"$tmp_file"

    echo '<pre>' >>"$tmp_file"
    (
        cd "$ROOT"
        go run main.go --help >>"$tmp_file"
    )
    echo '</pre>' >>"$tmp_file"

    sed -n "/$end_marker/,\$p" "$file" >>"$tmp_file"
    cp "$tmp_file" "$file"
    rm "$tmp_file"
}

# Execute the main function if the script is not being sourced.
if [[ "${BASH_SOURCE[0]}" == "${0}" ]]; then
    rdm:update "$@"
fi