A script for importing GitHub issues into a Fossil repository

import-github-issues.sh

#!/bin/bash

# +o histexpand is to avoid issues with ! showing up in ticket descriptions.
# The rest are just good Bash script practice.
set -eu -o pipefail +o histexpand

if [[ $# -lt 2 ]]; then
        echo "usage: $0 <user> <repo>"
        exit 1
fi

REPO_OWNER="$1"
REPO_NAME="$2"

github () {
        API_ENDPOINT="https://api.github.com"
        ACCEPT_HEADER="Accept: application/vnd.github.v3+json"

        if [[ ! -z "${GITHUB_TOKEN:-}" ]]; then
                RESULT=$(curl -s -H "${ACCEPT_HEADER}" -H "Authorization: token ${GITHUB_TOKEN}" "${API_ENDPOINT}$1")
        elif [[ ! -z "${GITHUB_USERNAME:-}" ]]; then
                RESULT=$(curl -s -H "${ACCEPT_HEADER}" -u "${GITHUB_USERNAME}" "${API_ENDPOINT}$1")
        else
                echo "One of GITHUB_TOKEN or GITHUB_USERNAME must be set. See https://developer.github.com/v3/?#authentication" >&2
                exit 1
        fi

        if [[ ! -z $(echo "${RESULT}" | jq '.message? | select(.!=null)') ]]; then
                echo "${RESULT}" >&2
                exit 1
        fi

        echo "${RESULT}"
}

for issue in $(github "/repos/${REPO_OWNER}/${REPO_NAME}/issues" | jq --raw-output --compact-output '.[] | @base64'); do
        _jq () {
                echo "${issue}" | base64 --decode | jq --raw-output $@
        }

        ticket_args=()
        ticket_args+=(title "'$(_jq '.title')'")
        ticket_args+=(type "'GitHub Issue'")

        # Convert markdown to HTML, then remove special characters.
        body=$(_jq '.body' | pandoc --from markdown --to html | sed $'s/\r/\\\\r/' | awk 1 ORS='\\n' | sed $'s/\'/\\\\\'/g')
        body+="<br><br><center><small>Imported from <a href=\"$(_jq '.html_url')\">GitHub</a></small></center>"
        ticket_args+=(comment "'${body}'")

        state=$(_jq --raw-output '.state')
        status=$(tr '[:lower:]' '[:upper:]' <<< ${state:0:1})${state:1}  # Capitalize the first letter, so e.g. "open" becomes "Open"
        ticket_args+=(status "'${status}'")

        email=$(github "/users/$(_jq .user.login)" | jq --raw-output '.email | select(.!=null)')
        if [[ ! -z "${email}" ]]; then
                ticket_args+=(private_contact "'${email}'")
        fi

        echo "${ticket_args[@]}" | xargs fossil ticket add --quote
done