#!/usr/bin/env bash

set -euo pipefail

handle_error() {
    cat <<EOF

It looks like quick-start setup has failed. Please run the command again
with the debug flag like below, and open an issue on
https://github.com/openzipkin/zipkin/issues/new. Make sure to include the
full output of the run.

    \curl -sSL http://zipkin.io/quickstart.sh | bash -sx

EOF
}

extract_latest_version() {
    package_data="$1"
    if \which jq >/dev/null 2>&1; then
        echo "$package_data" | jq '.latest_version' -r
    else
        echo "$package_data" | sed 's/^.*"latest_version" *: *"*\([^"]*\)".*$/\1/'
    fi
}

verify_version_number() {
    if ! echo "$1" | grep -E '^[0-9]+\.[0-9]+\.[0-9]+$' >/dev/null 2>&1; then
        cat <<EOF
It looks like the current version number is "$1". That doesn't look like a
valid Zipkin release version number; this script is confused. Bailing out.

EOF
        exit 1
    fi
}

verify_checksum() {
    url="$1"; shift
    filename="$1"; shift

    if \which md5sum >/dev/null 2>&1; then
        echo "Verifying checksum..."
        echo "$(curl -s "$url.md5")  $filename" > "$filename.md5"
        md5sum --check "$filename.md5"
    else
        echo "md5sum not found on path, skipping checksum verification"
    fi
}

verify_signature() {
    url="$1"; shift
    filename="$1"; shift

    bintray_gpg_key='D401AB61'

    if \which gpg >/dev/null 2>&1; then
        echo "Verifying signature of $filename..."
        curl -s -o "$filename.asc" "$url.asc"
        if gpg --list-keys "$bintray_gpg_key" >/dev/null 2>&1; then
            gpg --verify "$filename.asc" "$filename"
        else
            cat <<EOF
JFrog BinTray GPG signing key is not known, skipping signature verification.
You can import it, then verify the signature of $filename, using the following
commands:

    gpg --keyserver keyserver.ubuntu.com --recv D401AB61
    gpg --verify $filename.asc $filename

EOF
        fi
    else
        echo "gpg not found on path, skipping checksum verification"
    fi
}

main() {
    trap '[ $? -ne 0 ] && handle_error' EXIT
    cat <<EOF
Thank you for trying OpenZipkin!

This installer is provided as a quick-start helper, so you can try Zipkin out
without a lengthy installation process.

EOF
    echo 'Fetching version number of latest Zipkin release...'
    package_data="$(curl -fs  https://bintray.com/api/v1/packages/openzipkin/maven/zipkin)"
    latest_version="$(extract_latest_version "$package_data")"
    verify_version_number "$latest_version"

    echo "Downloading executable jar for Zipkin $latest_version..."
    url="https://dl.bintray.com/openzipkin/maven/io/zipkin/java/zipkin-server/$latest_version/zipkin-server-$latest_version-exec.jar"
    filename="zipkin-server-$latest_version-exec.jar"
    curl -s -o "$filename" "$url"
    verify_checksum "$url" "$filename"
    verify_signature "$url" "$filename"
    verify_signature "$url.md5" "$filename.md5"

    cat <<EOF

You can now run the Zipkin Server:

    java -jar $filename
EOF
}

main "$@"