FROM debian:jessie

# ensure local python is preferred over distribution python
ENV PATH /usr/local/bin:$PATH

# http://bugs.python.org/issue19846
# > At the moment, setting "LANG=C" on a Linux system *fundamentally breaks Python 3*, and that's not OK.
ENV LANG C.UTF-8

# runtime dependencies
RUN apt-get update && apt-get install -y --no-install-recommends \
		ca-certificates \
		libgdbm3 \
		libsqlite3-0 \
		libssl1.0.0 \
	&& rm -rf /var/lib/apt/lists/*

ENV GPG_KEY %%PLACEHOLDER%%
ENV PYTHON_VERSION %%PLACEHOLDER%%

# if this is called "PIP_VERSION", pip explodes with "ValueError: invalid truth value '<VERSION>'"
ENV PYTHON_PIP_VERSION %%PLACEHOLDER%%

RUN set -ex \
	&& buildDeps=' \
		gcc \
		libbz2-dev \
		libc6-dev \
		libgdbm-dev \
		liblzma-dev \
		libncurses-dev \
		libreadline-dev \
		libsqlite3-dev \
		libssl-dev \
		make \
		tcl-dev \
		tk-dev \
		wget \
		xz-utils \
		zlib1g-dev \
	' \
	&& apt-get update && apt-get install -y $buildDeps --no-install-recommends && rm -rf /var/lib/apt/lists/* \
	\
	&& wget -O python.tar.xz "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz" \
	&& wget -O python.tar.xz.asc "https://www.python.org/ftp/python/${PYTHON_VERSION%%[a-z]*}/Python-$PYTHON_VERSION.tar.xz.asc" \
	&& export GNUPGHOME="$(mktemp -d)" \
	&& gpg --keyserver ha.pool.sks-keyservers.net --recv-keys "$GPG_KEY" \
	&& gpg --batch --verify python.tar.xz.asc python.tar.xz \
	&& rm -r "$GNUPGHOME" python.tar.xz.asc \
	&& mkdir -p /usr/src/python \
	&& tar -xJC /usr/src/python --strip-components=1 -f python.tar.xz \
	&& rm python.tar.xz \
	\
	&& cd /usr/src/python \
	&& ./configure \
		--enable-loadable-sqlite-extensions \
		--enable-shared \
	&& make -j$(nproc) \
	&& make install \
	&& ldconfig \
	\
# explicit path to "pip3" to ensure distribution-provided "pip3" cannot interfere
	&& if [ ! -e /usr/local/bin/pip3 ]; then : \
		&& wget -O /tmp/get-pip.py 'https://bootstrap.pypa.io/get-pip.py' \
		&& python3 /tmp/get-pip.py "pip==$PYTHON_PIP_VERSION" \
		&& rm /tmp/get-pip.py \
	; fi \
# we use "--force-reinstall" for the case where the version of pip we're trying to install is the same as the version bundled with Python
# ("Requirement already up-to-date: pip==8.1.2 in /usr/local/lib/python3.6/site-packages")
# https://github.com/docker-library/python/pull/143#issuecomment-241032683
	&& pip3 install --no-cache-dir --upgrade --force-reinstall "pip==$PYTHON_PIP_VERSION" \
# then we use "pip list" to ensure we don't have more than one pip version installed
# https://github.com/docker-library/python/pull/100
	&& [ "$(pip list |tac|tac| awk -F '[ ()]+' '$1 == "pip" { print $2; exit }')" = "$PYTHON_PIP_VERSION" ] \
	\
	&& find /usr/local -depth \
		\( \
			\( -type d -a -name test -o -name tests \) \
			-o \
			\( -type f -a -name '*.pyc' -o -name '*.pyo' \) \
		\) -exec rm -rf '{}' + \
	&& apt-get purge -y --auto-remove $buildDeps \
	&& rm -rf /usr/src/python ~/.cache

# make some useful symlinks that are expected to exist
RUN cd /usr/local/bin \
	&& { [ -e easy_install ] || ln -s easy_install-* easy_install; } \
	&& ln -s idle3 idle \
	&& ln -s pydoc3 pydoc \
	&& ln -s python3 python \
	&& ln -s python3-config python-config

CMD ["python3"]