#!/bin/bash
#
# Builds a dockerized service defined by a docker-compose.yml file.
# This is a general purpose launcher, doesn't requires customization.
# Actually it is a humble wrapper script for a 'docker-compose build'
# command. Always pulls the latest image(s) from repository.
#
# Author: Kovács Zoltán <kovacs.zoltan@smartfront.hu>
#         Kovács Zoltán <kovacsz@marcusconsulting.hu>
# License: GNU/GPL v3+ (https://www.gnu.org/licenses/gpl-3.0.en.html)
# 2024-08-24 v1.1
# new: docker-compose v2 compatibility - tested with Ubuntu 24.04 LTS.
# 2023-06-18 v1.0
# new: forked from the "Smartfront's DOCKER_skeleton" repository.
# 2021-10-03 v0.2
# fix: now pulls the images even if the service doesn't requires build.
# 2021-08-30 v0.1 Initial release

# Accepted environment variables and their defaults.
PAR_BASEDIR=${PAR_BASEDIR:-""}			# Service's base folder.

# Other initialisations.
YMLFILE="docker-compose.yml"

# Messages.
MSG_ALREADYRUN="This service is running - shut down before build."
MSG_MISSINGDEP="Fatal: missing dependency"
MSG_MISSINGYML="Fatal: didn't find the docker-compose.yml file"

# Checks the dependencies.
TR=$(which tr 2>/dev/null)
if [ -z "$TR" ]; then echo "$MSG_MISSINGDEP tr."; exit 1 ; fi
for item in dirname docker readlink
do
    if [ -n "$(which $item)" ]
    then export $(echo $item | "$TR" '[:lower:]' '[:upper:]' | "$TR" '-' '_')=$(which $item)
    else echo "$MSG_MISSINGDEP $item." >&2; exit 1; fi
done
#
# Let's find which version of docker-compose is installed.
commandstring=""
if [ $($DOCKER compose version 2>&1 >/dev/null; echo $?) -eq 0 ]; then
    # We'll use v2 if it is available.
    DOCKER_COMPOSE="$DOCKER"
    commandstring="compose"
else
    # Otherwise falling back to v1.
    DOCKER_COMPOSE="$(which docker-compose)"
    commandstring=""
fi
# One of the two is mandatory.
if [ -z "$DOCKER_COMPOSE" ];then echo "$MSG_MISSINGDEP docker-compose" >&2; exit 1; fi
# All dependencies are available via "$THECOMMAND" (upper case) call.
# In addition "docker-compose" should be called as "$DOCKER_COMPOSE" $commandstring.

# Where I'm?
# https://gist.github.com/TheMengzor/968e5ea87e99d9c41782
SOURCE="$0"
while [ -h "$SOURCE" ]; do
    # resolve $SOURCE until the file is no longer a symlink
    SCRPATH="$( cd -P "$("$DIRNAME" "$SOURCE" )" && pwd )" #"
    SOURCE="$("$READLINK" "$SOURCE")"
    # if $SOURCE was a relative symlink, we need to resolve it
    # relative to the path where the symlink file was located
    [[ $SOURCE != /* ]] && SOURCE="$SCRPATH/$SOURCE"
done; SCRPATH="$( cd -P "$("$DIRNAME" "$SOURCE" )" && pwd )" #"

# Searches the base folder, containing a docker-compose.yml file.
# Called from the base folder (./)?
BASE_DIR="$PAR_BASEDIR"
TEST_DIR="$SCRPATH"
[[ -z "$BASE_DIR" ]] && [[ -r "$TEST_DIR/$YMLFILE" ]] && BASE_DIR="$TEST_DIR"
# Called from ./tools?
TEST_DIR="$("$DIRNAME" "$TEST_DIR")"
[[ -z "$BASE_DIR" ]] && [[ -r "$TEST_DIR/$YMLFILE" ]] && BASE_DIR="$TEST_DIR"
# Called from ./tools/*.d?
TEST_DIR="$("$DIRNAME" "$TEST_DIR")"
[[ -z "$BASE_DIR" ]] && [[ -r "$TEST_DIR/$YMLFILE" ]] && BASE_DIR="$TEST_DIR"
# On failure gives it up here.
if [ -z "$BASE_DIR" -o ! -r "$BASE_DIR/$YMLFILE" ]; then
    echo "$MSG_MISSINGYML" >&2; exit 1
fi

# Doesn't attempts to build if the service is running.
if [ -n "$(cd "$BASE_DIR"; "$DOCKER_COMPOSE" $commandstring ps --services --filter "status=running")" ]; then
    echo "$MSG_ALREADYRUN" >&2; exit 1
fi
# Pulls the components and builds the service (if necessary).
(cd "$BASE_DIR"; "$DOCKER_COMPOSE" $commandstring rm -f; "$DOCKER_COMPOSE" $commandstring pull; "$DOCKER_COMPOSE" $commandstring build)

# That's all, Folks!