#!/bin/bash

set -eu

usage() {
    echo "Usage:"
    echo "scope launch [<peer> ...]"
    echo "scope stop"
    echo
    echo "scope <peer>    is of the form <ip_address_or_fqdn>[:<port>]"
    exit 1
}

SCRIPT_VERSION="(unreleased version)"
if [ "$SCRIPT_VERSION" = "(unreleased version)" ] ; then
    IMAGE_VERSION=latest
else
    IMAGE_VERSION=$SCRIPT_VERSION
fi
IMAGE_VERSION=${VERSION:-$IMAGE_VERSION}
SCOPE_IMAGE=weaveworks/scope:$IMAGE_VERSION
SCOPE_CONTAINER_NAME=weavescope
WEAVE_CONTAINER_NAME=weave
DNS_CONTAINER_NAME=weavedns
DNS_HTTP_PORT=6785
HOSTNAME=scope
DOMAINNAME=weave.local
FQDN=$HOSTNAME.$DOMAINNAME
DOCKER_BRIDGE=${DOCKER_BRIDGE:-docker0}
IP_REGEXP="[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}\.[0-9]{1,3}"
IP_ADDR_CMD="find /sys/class/net -type l | xargs -n1 basename | grep -vE 'docker|veth|lo' | \
    xargs -n1 ip addr show | grep inet | awk '{ print \$2 }' | grep -oE '$IP_REGEXP'"

WEAVESCOPE_DOCKER_ARGS=${WEAVESCOPE_DOCKER_ARGS:-}
WEAVESCOPE_DNS_ARGS=${WEAVESCOPE_DNS_ARGS:-}

[ $# -gt 0 ] || usage
COMMAND=$1
shift 1

# http://stackoverflow.com/questions/592620/how-to-check-if-a-program-exists-from-a-bash-script
command_exists() {
    command -v $1 >/dev/null 2>&1
}

is_running() {
    status=$(docker inspect --format='{{.State.Running}}' $1 2>/dev/null) && [ "$status" = "true" ]
    return $?
}

# Check that a container named $1 with image $2 is not running
check_not_running() {
    case $(docker inspect --format='{{.State.Running}} {{.Config.Image}}' $1 2>/dev/null) in
        "true $2")
            echo "$1 is already running." >&2
            exit 1
            ;;
        "true $2:"*)
            echo "$1 is already running." >&2
            exit 1
            ;;
        "false $2")
            docker rm $1 >/dev/null
            ;;
        "false $2:"*)
            docker rm $1 >/dev/null
            ;;
        true*)
            echo "Found another running container named '$1'. Aborting." >&2
            exit 1
            ;;
        false*)
            echo "Found another container named '$1'. Aborting." >&2
            exit 1
            ;;
    esac
}

# Run `weave expose` if it's not already exposed.
weave_expose() {
    status=$(weave ps weave:expose | awk '{print $3}' 2>/dev/null)
    if [ "$status" == "" ]; then
        weave expose
    fi
}

# Add all Scope IPs to its DNS record.
weave_dns_add() {
    CONTAINER_ID="$1"
    CONTAINER_FQDN="$2"
    shift 2

	for ip in $*; do
        weave dns-add $ip $CONTAINER_ID -h $CONTAINER_FQDN
    done
}

set_docker_bridge_ip() {
    DOCKER_BRIDGE_IP=$(ip -4 addr show dev $DOCKER_BRIDGE | grep -m1 -o 'inet [.0-9]*')
    DOCKER_BRIDGE_IP=${DOCKER_BRIDGE_IP#inet }
}

# Call url $4 with http verb $3 on container $1 at port $2
http_call() {
    container_ip $1 \
        "$1 container is not present. Have you launched it?" \
        "$1 container is not running." \
        || return 1
    shift 1
    http_call_ip $CONTAINER_IP "$@"
}

http_call_ip() {
    ip="$1"
    port="$2"
    http_verb="$3"
    url="$4"
    shift 4
    curl --connect-timeout 3 -s -X $http_verb "$@" http://$ip:$port$url
}

container_ip() {
    if ! status=$(docker inspect --format='{{.State.Running}} {{.NetworkSettings.IPAddress}}' $1 2>/dev/null); then
        echo "$2" >&2
        return 1
    fi
    case "$status" in
        "true ")
            echo "$1 container has no IP address; is Docker networking enabled?" >&2
            return 1
            ;;
        true*)
            CONTAINER_IP="${status#true }"
            ;;
        *)
            echo "$3" >&2
            return 1
            ;;
    esac
}

case "$COMMAND" in

    launch)
        check_not_running $SCOPE_CONTAINER_NAME $SCOPE_IMAGE

        # If Weave is running, we want to expose a Weave IP to the host
        # network namespace, so Scope can use it.
        if is_running $WEAVE_CONTAINER_NAME && command_exists weave; then
            weave_expose
        fi

        # If WeaveDNS is running, we want to automatically tell the scope
        # image to use weave dns.  We can't use --dns with --net=host, so we
        # have to hack it.
        if is_running $DNS_CONTAINER_NAME; then
            set_docker_bridge_ip
            WEAVESCOPE_DNS_ARGS="$WEAVESCOPE_DNS_ARGS --dns $DOCKER_BRIDGE_IP --searchpath $DOMAINNAME"
        fi

        CONTAINER=$(docker run --privileged -d --name=$SCOPE_CONTAINER_NAME --net=host --pid=host \
            -v /var/run/docker.sock:/var/run/docker.sock \
            $WEAVESCOPE_DOCKER_ARGS $SCOPE_IMAGE $WEAVESCOPE_DNS_ARGS "$@")

        IP_ADDRS=$(docker run --net=host gliderlabs/alpine /bin/sh -c "$IP_ADDR_CMD")
        if is_running $DNS_CONTAINER_NAME && is_running $WEAVE_CONTAINER_NAME && command_exists weave; then
            if [ -z "$IP_ADDRS" ]; then
                echo "Could not determine local IP address; Weave DNS integration will not work correctly."
                exit 1
            fi
            weave_dns_add $CONTAINER $FQDN $IP_ADDRS
        fi

        echo $CONTAINER

        echo "Weave Scope is reachable at the following URL(s):" >&2
        for ip in $IP_ADDRS; do
            echo "  * http://$ip:4040/" >&2
        done
        ;;

    stop)
        [ $# -eq 0 ] || usage
        if ! docker stop $SCOPE_CONTAINER_NAME >/dev/null 2>&1 ; then
            echo "Weave Scope is not running." >&2
        fi
        docker rm -f $SCOPE_CONTAINER_NAME >/dev/null 2>&1 || true
        ;;

    *)
        echo "Unknown scope command '$COMMAND'" >&2
        usage
        ;;

esac