#!/bin/bash

## Bash wrap script to launch the ``compose`` docker with right options.
##
##

## Launcher
##  - should need minimum requirement to run
##    - no shell libs
##


get_os() {
    local uname_output machine

    uname_output="$(uname -s)"
    case "${uname_output}" in
        Linux*)   machine=linux;;
        Darwin*)  machine=mac;;
        CYGWIN*)  machine=cygwin;;
        MINGW*)   machine=mingw;;
        *)        machine="UNKNOWN:${uname_output}"
    esac
    echo "${machine}"
}


read-0() {
    local eof= IFS=''
    while [ "$1" ]; do
        read -r -d '' -- "$1" || eof=1
        shift
    done
    [ -z "$eof" ]
}


get_running_compose_containers() {
    ## XXXvlab: docker bug: there will be a final newline anyway
    docker ps --filter label="compose.service" --format='{{.ID}}'
}


get_volumes_for_container() {
    local container="$1"

    docker inspect \
           --format '{{range $mount := .Mounts}}{{$mount.Source}}{{"\x00"}}{{$mount.Destination}}{{"\x00"}}{{end}}' \
           "$container"
}


is_volume_used() {
    local volume="$1"

    while read container_id; do
        while read-0 src dst; do
            [ "$src" == "$volume" ] && return 0
        done < <(get_volumes_for_container "$container_id")
    done < <(get_running_compose_containers)
    return 1
}


clean_unused_sessions() {
    for f in "$COMPOSE_VAR/sessions/"*; do
        [ -e "$f" ] || continue
        is_volume_used "$f" && continue
        rm -f "$f"
    done
}


relink_subdirs() {
    local dir
    for dir in "$@"; do
        [ -L "$dir" ] || continue
        target=$(realpath "$dir")
        [ -d "$target" ] || continue
        docker_run_opts+=("-v" "$target:$dir")
        [ -e "$dir/metadata.yml" ] && continue
        relink_subdirs "$dir"/*
    done
}


mk_docker_run_options() {

    docker_run_opts=("-v" "/var/run/docker.sock:/var/run/docker.sock")

    ## CACHE/DATA DIRS
    docker_run_opts+=("-v" "$COMPOSE_VAR:/var/lib/compose")
    docker_run_opts+=("-v" "$COMPOSE_CACHE:/var/cache/compose")

    docker_run_opts+=("-v" "$TZ_PATH:/etc/timezone:ro")


    ## current dir
    if parent=$(while true; do
                    [ -e "./compose.yml" ] && {
                        echo "$PWD"
                        exit 0
                    }
                    [ "$PWD" == "/" ] && exit 1
                    cd ..
                done
             ); then
        docker_path=$COMPOSE_VAR/root/$(basename "$parent")
        docker_run_opts+=("-v" "$parent:$docker_path:ro" \
                               "-w" "$docker_path")
    fi


    ##
    ## Load config files
    ##

    if [ -z "$DISABLE_SYSTEM_CONFIG_FILE" ]; then
        ## XXXvlab: should provide YML config opportunities in possible parent dirs ?
        ##  userdir ? and global /etc/compose.yml ?
        for cfgfile in "${compose_config_files[@]}"; do
            [ -e "$cfgfile" ] || continue
            docker_run_opts+=("-v" "$cfgfile:$cfgfile:ro")
            . "$cfgfile"
        done
    else
        docker_run_opts+=("-e" "DISABLE_SYSTEM_CONFIG_FILE=$DISABLE_SYSTEM_CONFIG_FILE")
    fi


    ##
    ## Checking vars
    ##

    ## CHARM_STORE
    CHARM_STORE=${CHARM_STORE:-/srv/charm-store}
    [ -L "$CHARM_STORE" ] && {
        CHARM_STORE=$(readlink -f "$CHARM_STORE") || exit 1
    }
    docker_run_opts+=(
        "-v" "$CHARM_STORE:/srv/charm-store:ro"
        "-e" "CHARM_STORE=/srv/charm-store"
        "-e" "HOST_CHARM_STORE=$CHARM_STORE"
    )
    relink_subdirs /srv/charm-store/*

    ## DEFAULT_COMPOSE_FILE
    if [ "${DEFAULT_COMPOSE_FILE+x}" ]; then
        DEFAULT_COMPOSE_FILE=$(realpath "$DEFAULT_COMPOSE_FILE")
        dirname=$(dirname "$DEFAULT_COMPOSE_FILE")/
        if [ -e "${DEFAULT_COMPOSE_FILE}" ]; then
            docker_run_opts+=("-v" "$dirname:$dirname:ro")
        fi
    fi

    ## COMPOSE_YML_FILE
    if [ "${COMPOSE_YML_FILE+x}" ]; then
        if [ -e "${COMPOSE_YML_FILE}" ]; then
            docker_run_opts+=(
                "-v" "$COMPOSE_YML_FILE:/tmp/compose.yml:ro"
                "-e" "COMPOSE_YML_FILE=/tmp/compose.yml"
                "-e" "HOST_COMPOSE_YML_FILE=/tmp/compose.yml"
            )
        fi
    fi

    ## DATASTORE
    DATASTORE=${DATASTORE:-/srv/datastore/data}
    docker_run_opts+=(
        "-v" "$DATASTORE:/srv/datastore/data:rw"
        "-e" "DATASTORE=/srv/datastore/data"
        "-e" "HOST_DATASTORE=$DATASTORE"
    )

    ## CONFIGSTORE
    CONFIGSTORE=${CONFIGSTORE:-/srv/datastore/config}
    docker_run_opts+=(
        "-v" "$CONFIGSTORE:/srv/datastore/config:rw"
        "-e" "CONFIGSTORE=/srv/datastore/config"
        "-e" "HOST_CONFIGSTORE=$CONFIGSTORE"
    )

    docker_run_opts+=("-v" "$HOME/.docker:/root/.docker")

    COMPOSE_DOCKER_IMAGE=${COMPOSE_DOCKER_IMAGE:-docker.0k.io/compose}
    docker_run_opts+=("-e" "COMPOSE_DOCKER_IMAGE=$COMPOSE_DOCKER_IMAGE")

    COMPOSE_LAUNCHER_BIN=$(readlink -f "${BASH_SOURCE[0]}")
    docker_run_opts+=("-v" "$COMPOSE_LAUNCHER_BIN:/usr/local/bin/compose")

    filename=$(mktemp -p /tmp/ -t launch_opts-XXXXXXXXXXXXXXXX)
    {
        printf "%s\0" "${docker_run_opts[@]}"
    } > "$filename"
    sha=$(sha256sum "$filename")
    sha=${sha:0:64}
    dest="$COMPOSE_VAR/sessions/$sha"
    {
        printf "%s\0" "-v" "$dest:$dest"
        printf "%s\0" "-e" "COMPOSE_LAUNCHER_OPTS=$dest"
        printf "%s\0" "-e" "COMPOSE_LAUNCHER_BIN=$COMPOSE_LAUNCHER_BIN"
    } >> "$filename"
    mkdir -p "$COMPOSE_VAR"/sessions
    mv "$filename" "$dest"
    echo "$dest"
}


run() {
    local os docker_run_opts

    ## Order matters, files get to override vars
    compose_config_files=(
        /etc/default/charm
        /etc/default/datastore
        /etc/compose.conf
        /etc/compose.local.conf
        /etc/default/compose
        ~/.compose/etc/local.conf
        /etc/compose/local.conf
    )

    os=$(get_os)
    case "$os" in
        linux)
            COMPOSE_VAR=/var/lib/compose
            COMPOSE_CACHE=/var/cache/compose
            TZ_PATH=/etc/timezone
            ;;
        mac)
            if ! [ -e "$HOME/.compose/etc/timezone" ]; then
                TZ=${TZ:-"Europe/Paris"}
                echo "$TZ" > "$HOME"/.compose/etc/timezone
            fi
            TZ_PATH="$HOME"/.compose/etc/timezone
            COMPOSE_VAR="$HOME"/.compose/lib
            COMPOSE_CACHE="$HOME"/.compose/cache
            ;;
        *)
            echo "System '$os' not supported yet." >&2
            exit 1
            ;;
    esac


    docker_run_opts=()
    if [ -z "$COMPOSE_LAUNCHER_OPTS" ]; then
        clean_unused_sessions
        COMPOSE_LAUNCHER_OPTS="$(mk_docker_run_options)"
    fi

    while read-0 opt; do
        docker_run_opts+=("$opt")
        ## catch COMPOSE_DOCKER_IMAGE
        if [[ "$env" == "true" && "$opt" == "COMPOSE_DOCKER_IMAGE="* ]]; then
            COMPOSE_DOCKER_IMAGE=${opt##COMPOSE_DOCKER_IMAGE=}
        elif [ "$opt" == "-e" ]; then
            env=true
        else
            env=
        fi
    done < <(cat "$COMPOSE_LAUNCHER_OPTS")

    if [ -t 0 ]; then
        docker_run_opts+=("-i")
    fi
    if [ -t 1 ]; then
        docker_run_opts+=("-t")
    fi
    exec docker run --rm "${docker_run_opts[@]}" "${COMPOSE_DOCKER_IMAGE}" "$@"
}


run "$@"