#!/usr/bin/env bash

# THIS FILE IS PART OF THE CYLC WORKFLOW ENGINE.
# Copyright (C) NIWA & British Crown (Met Office) & Contributors.
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <http://www.gnu.org/licenses/>.

#------------------------------------------------------------------------------
# Wrapper script to support multiple installed Cylc, Rose & Isodatetime
# versions. Handles Conda and Python virtual environments, and legacy plain
# installations.
#
# WRAPPER INSTALLATION AND CONFIGURATION
# --------------------------------------
# - Copy this script as "cylc" into default $PATH, on scheduler and job hosts
# - Create an "isodatetime" symlink (ln -s cylc isodatetime)
# - If using Rose, create "rose" & "rosie" symlinks
# - Set CYLC_HOME_ROOT ("EDIT ME" below) to default to the parent directory of
#   installed versions and set the global config locations if necessary
#
# HOW IT WORKS
# ------------
# Intercept "cylc", "rose", "rosie" and "isodatetime" commands and re-invoke
# them with the version selected via the environment variables described below.
#
# Additional legacy logic is used when calling Rose with Cylc 7.
#
# ENVIRONMENT VARIABLES
# ---------------------
#
# CYLC_VERSION - can be set by users (e.g. in .bash_profile) in order to select a
# specific Cylc environment. If set this wrapper will look for an installed
# environment called cylc-$CYLC_VERSION in the ROOT locations (if not set it will
# look for an installed environment called cylc).
# e.g.    export CYLC_VERSION=8.0.0-1
#
# CYLC_HOME_ROOT - location of installed Cylc environments.
# Usually defined in this wrapper script.
#
# CYLC_HOME_ROOT_ALT - alternate location of installed Cylc environments.
# Can be set by users for use with their own Cylc environments.
# If used it must be set on workflow and job hosts, e.g. in .bash_profile.
# e.g.    export CYLC_HOME_ROOT_ALT=$HOME/miniconda3/envs
#
# CYLC_ENV_NAME - gets set to the basename of the selected environment.
# If set this defines the environment name rather than CYLC_VERSION.
# The scheduler sets CYLC_ENV_NAME for all remote commands to ensure the same
# environment is used on all platforms.
# Users should not set CYLC_ENV_NAME (use CYLC_VERSION).
#
# CYLC_HOME - full path to the Cylc environment.
# Can be set by users in order to use an environment outside of the ROOT
# locations. However, it is not passed by the scheduler to remote platforms so
# use of CYLC_VERSION & CYLC_HOME_ROOT_ALT is preferred.
#
# INSTALLING ENVIRONMENTS
# -----------------------
#
# Releases should be installed into environments in the ROOT location, named
# cylc-$CYLC_VERSION. We recommend using the cylc-flow version plus an additional
# suffix to allow for multiple environments containing the same cylc-flow
# version. e.g. cylc-8.0.0-1
#
# A cylc symlink should be created in the ROOT location to define the default
# version to used. e.g. ln -s cylc-8.0.0-1 cylc
# Other symlinks can be created in order to create additional named environments
# for selection using CYLC_VERSION. e.g. ln -s cylc-8.0.1-1 cylc-next
#
# Legacy Cylc 7 and Rose 2019.01 versions can also be installed into environments
# in the ROOT location. The legacy support for rose edit and rosie
# requires cylc-7 and rose-2019.01 symlinks to be created to the preferred
# environments.
# e.g.    ln -s cylc-7.9.5 cylc-7
#         ln -s rose-2019.01.7 rose-2019.01
#
##############################!!! EDIT ME !!!##################################
# Centrally installed Cylc releases:
CYLC_HOME_ROOT="${CYLC_HOME_ROOT:-/opt}"

# Users can set CYLC_HOME_ROOT_ALT as well (see above), e.g.:
# CYLC_HOME_ROOT_ALT=${HOME}/miniconda3/envs

# Global config locations for Cylc 8 & Rose 2 (defaults: /etc/cylc & /etc/rose)
# export CYLC_SITE_CONF_PATH="${CYLC_SITE_CONF_PATH:-/etc/cylc}"
# export ROSE_SITE_CONF_PATH="${ROSE_SITE_CONF_PATH:-/etc/rose}"
###############################################################################

if [[ -z "${CYLC_HOME}" ]]; then
    if [[ -z "${CYLC_ENV_NAME}" ]]; then
        if [[ -n "${CYLC_VERSION}" ]]; then
            CYLC_ENV_NAME="cylc-$CYLC_VERSION"
        else
            # Use default version (symlink)
            CYLC_ENV_NAME="cylc"
        fi
    fi
    # CYLC_VERSION gets set to the actual version of Cylc used within workflows.
    # Therefore we export CYLC_ENV_NAME to ensure it gets used rather than
    # CYLC_VERSION in subsequent calls to the wrapper.
    export CYLC_ENV_NAME
    for ROOT in "${CYLC_HOME_ROOT}" "${CYLC_HOME_ROOT_ALT}"; do
        if [[ -d "${ROOT}/${CYLC_ENV_NAME}" ]]; then
            CYLC_HOME="${ROOT}/${CYLC_ENV_NAME}"
            # If CYLC_HOME is a symlink then replace it with the real path and
            # set CYLC_ENV_NAME to the linked environment to ensure changes to
            # symlinked environments can't affect running workflows.
            if [[ -L ${CYLC_HOME} ]]; then
                CYLC_HOME=$(readlink -f "${CYLC_HOME}")
                CYLC_ENV_NAME=${CYLC_HOME##*/}
            fi
            break
        fi
    done
    if [[ -z "${CYLC_HOME}" ]]; then
        MSG="ERROR: $CYLC_ENV_NAME not found in $CYLC_HOME_ROOT"
        if [[ -n "${CYLC_HOME_ROOT_ALT}" ]]; then
            MSG="${MSG} or ${CYLC_HOME_ROOT_ALT}"
        fi
        echo 1>&2 "$MSG"
        exit 1
    fi
fi

# Legacy support for Rose
if [[ ${0##*/} =~ ^ros ]]; then
    # Prior to Cylc 8, Rose used a standalone installation
    if [[ -n "${CYLC_ENV_NAME}" ]]; then
        ROSE_HOME_ROOT="${ROSE_HOME_ROOT:-$CYLC_HOME_ROOT}"
        if [[ ${CYLC_ENV_NAME:-} =~ ^cylc-7 ]]; then
            # Cylc 7: Use ROSE_HOME / ROSE_VERSION to select the installation
            if [[ -z "${ROSE_HOME:-}" ]]; then
                if [[ -n "${ROSE_VERSION:-}" ]]; then
                    CYLC_HOME="${ROSE_HOME_ROOT}/rose-${ROSE_VERSION}"
                else
                    # Use default version (symlink)
                    CYLC_HOME="${ROSE_HOME_ROOT}/rose"
                fi
            else
                CYLC_HOME="${ROSE_HOME}"
            fi
        elif [[ ${1:-} == "edit" || ${1:-} == "config-edit" || \
                ${0##*/} == "rosie" ]]; then
            # Cylc 8: Use Rose 2019.01 to run "rose config-edit" or "rosie"
            CYLC_HOME="${ROSE_HOME_ROOT}/rose-2019.01"
        fi
    elif [[ -z "${CYLC_ENV_NAME}" ]]; then
        # If CYLC_HOME was set externally, use ROSE_HOME if it is set
        CYLC_HOME="${ROSE_HOME:-$CYLC_HOME}"
    fi
fi

if [[ ! -x "${CYLC_HOME}/bin/${0##*/}" ]]; then
    echo 1>&2 "ERROR: ${0##*/} not found in ${CYLC_HOME}"
    exit 1
fi

# Set PATH when running cylc hub so that configurable-http-proxy can find node
if [[ ${0##*/} == "cylc" && ${1:-} == "hub" ]]; then
    PATH=${PATH}:${CYLC_HOME}/bin
fi

# Run the executable from the selected installation.
# n.b. If CYLC_HOME points to a binary inside a
# ``conda/envs/bin directory`` this is sufficient without using
# ``conda activate``. We avoid ``conda activate`` because:
# - It's slow.
# - Subsequent environment changes (conda activate or deactivate)
#   are not straightforward.
exec "${CYLC_HOME}/bin/${0##*/}" "$@"
