Setup pyenv and pipenv from .python-history and Pipfile

pyenv-setup.sh

#!/bin/bash

# Set up pyenv from .python-version.
# If the current folder contains Pipfile, pipenv and all dependencies will also be installed.

error() { # msg
    echo ERROR "$@" 1>&2
    exit 1
}

containsElement () { # pattern array...
    local it pattern="$1"
    shift
    for it; do [[ "$it" == "$pattern" ]] && return 0; done
    return 1
}

if [[ $(type -t pyenv) == "" ]]; then
    error "Unable to find pyenv on PATH"
fi

if [[ ! -e .python-version ]]; then
    error "Missing $PWD/.python-version"
fi

required_version=$(pyenv version-name)
if [[ "$required_version" == */envs/* ]]; then
    echo "INFO Detected virtualenv"
    python_version=${required_version%%/*}
    echo "INFO Installing base python $python_version"
    pyenv install --skip-existing "$python_version" || exit 1

    venv_name=${required_version##*/}
    declare -a existing_venvs=( $(pyenv virtualenvs --bare) )
    if containsElement "$required_version" "${existing_venvs[@]}"; then
        echo "INFO venv already exists"
    else
        echo "INFO Creating virtualenv $required_version"
        pyenv virtualenv "$python_version" "$venv_name" || exit 1
    fi
else
    echo "INFO Installing python $required_version"
    pyenv install --skip-existing "$required_version"
fi

echo "INFO Your python version is:"
pyenv exec python -c 'import sys; print(sys.version)' || exit 1

if [[ -e Pipfile ]]; then
    echo "INFO Detected pipenv."
    if pyenv exec pip show pipenv > /dev/null; then
        :
    else
        pyenv exec pip install pipenv
    fi
    echo "INFO Installing dependencies..."
    pyenv exec pipenv install --dev
fi

echo "SUCCESS"