#    Licensed under the Apache License, Version 2.0 (the "License"); you may
#    not use this file except in compliance with the License. You may obtain
#    a copy of the License at
#
#         http://www.apache.org/licenses/LICENSE-2.0
#
#    Unless required by applicable law or agreed to in writing, software
#    distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
#    WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
#    License for the specific language governing permissions and limitations
#    under the License.

OVS_REPO=${OVS_REPO:-https://github.com/openvswitch/ovs.git}
OVS_REPO_NAME=$(basename ${OVS_REPO} | cut -f1 -d'.')
OVS_BRANCH=${OVS_BRANCH:-master}

# Functions

# load_module() - Load module using modprobe module given by argument and dies
#                 on failure
#               - fatal argument is optional and says whether function should
#                 exit if module can't be loaded
function load_module {
    local module=$1
    local fatal=$2

    if [ "$(trueorfalse True fatal)" == "True" ]; then
        sudo modprobe $module || (dmesg && die $LINENO "FAILED TO LOAD $module")
    else
        sudo modprobe $module || (echo "FAILED TO LOAD vport_geneve" && dmesg)
    fi
}

# is_kernel_supported_for_ovs25() - compilation of openvswitch 2.5 kernel module
#                                   supports only kernels up to 4.3.x, function
#                                   determines whether compilation from source
#                                   will succeed on this machine
function is_kernel_supported_for_ovs25 {
    major=$(uname -r | cut -d\. -f 1)
    minor=$(uname -r | cut -d\. -f 2)
    if [ $major -le 3 ]; then
        # All 3.x branches and lesser are supported
        return 0
    elif [ $major -eq 4 -a $minor -le 3 ]; then
        # If it's version 4, minor must not be higher than 3
        return 0
    fi

    return 1
}

# is_version_le() - Helper function to test if the first version string is less
#                   than or equal to the second version string
function is_version_le {
    version1=$1
    version2=$2
    echo -e "$version1\\n$version2" | sort -VC
    return $?
}


# is_kernel_supported_for_ovs261() - compilation of openvswitch 2.6.1 kernel
#                                    module supports only kernels versions
#                                    between 3.10 and 4.8 (inclusive)
#                                    Taken from the OVS tree (acinclude.m4)
function is_kernel_supported_for_ovs261 {
    major=$(uname -r | cut -d\. -f 1)
    minor=$(uname -r | cut -d\. -f 2)
    kversion="$major.$minor"
    minimum_version="3.10"
    maximum_version="4.8"
    if ! is_version_le $minimum_version $kversion; then
        return 1
    fi
    if ! is_version_le $kversion $maximum_version ; then
        return 1
    fi
    return 0
}

# is_ovs_version_ok() - Verify the OVS version is new enough. Specifically,
#                       verify the OVS version >= 2.5.1
function is_ovs_version_ok {
    minimum_version="2.5.1"
    version_string=$(ovs-vswitchd -V | awk '/^ovs-vswitchd/ { print $NF}')
    is_version_le $minimum_version $version_string
    return $?
}

# upgrade_ovs_if_necessary() - Check if OVS version is high enough ( >= 2.5.1)
#                              and upgrade if necessary.
#                              Accepts one optional parameter for kernel modules compilation:
#                                 - first parameter is True by default and it means OVS will be
#                                   compiled with kernel modules. False won't compile kernel modules.
function upgrade_ovs_if_necessary {
    local compile_modules=${1:-True}
    if ! is_ovs_version_ok; then
        if [ "$NEUTRON_OVERRIDE_OVS_BRANCH" ]; then
            OVS_BRANCH=$NEUTRON_OVERRIDE_OVS_BRANCH
        elif is_kernel_supported_for_ovs25; then
            # The order of conditions here is such that on Trusty we install
            # version 2.5.1, and on Xenial we upgrade to 2.6.1 (Since Xenial
            # kernel is not compatible with 2.5.1)
            OVS_BRANCH="v2.5.1"
        elif is_kernel_supported_for_ovs261; then
            OVS_BRANCH="v2.6.1"
        else
            echo "WARNING: Unsupported kernel for OVS compilation. Trying default branch."
        fi
        echo "Compiling OVS branch: $OVS_BRANCH"
        remove_ovs_packages
        compile_ovs $compile_modules /usr /var
        start_new_ovs
    fi
}

# compile_ovs() - Compile OVS from source and load needed modules.
#                 Accepts two parameters:
#                   - first one is True by default and means that modules are built and installed.
#                   - second optional parameter defines prefix for ovs compilation
#                   - third optional parameter defines localstatedir for ovs single machine runtime
#                 Env variables OVS_REPO_NAME, OVS_REPO and OVS_BRANCH must be set
function compile_ovs {
    local _pwd=$PWD
    local build_modules=${1:-True}
    local prefix=$2
    local localstatedir=$3

    if [ -n "$prefix" ]; then
        prefix="--prefix=$prefix"
    fi

    if [ -n "$localstatedir" ]; then
        localstatedir="--localstatedir=$localstatedir"
    fi

    OVS_DIR=$DEST/$OVS_REPO_NAME
    if [ ! -d $OVS_DIR ] ; then
        # We can't use git_clone here because we want to ignore ERROR_ON_CLONE
        git_timed clone $OVS_REPO $OVS_DIR
        cd $OVS_DIR
        git checkout $OVS_BRANCH
    else
        # Even though the directory already exists, call git_clone to update it
        # if needed based on the RECLONE option
        git_clone $OVS_REPO $OVS_DIR $OVS_BRANCH
        cd $OVS_DIR
    fi

    # TODO: Can you create package list files like you can inside devstack?
    install_package autoconf automake libtool gcc patch make

    if is_fedora ; then
        # is_fedora covers Fedora, RHEL, CentOS, etc...
        echo NOTE: if kernel-devel-$(uname -r) or kernel-headers-$(uname -r) installation
        echo failed, please, provide a repository with the package, or yum update / reboot
        echo your machine to get the latest kernel.

        install_package kernel-devel-$(uname -r)
        install_package kernel-headers-$(uname -r)

    elif is_ubuntu ; then
        install_package linux-headers-$(uname -r)
    fi

    if [ ! -f configure ] ; then
        ./boot.sh
    fi
    if [ ! -f config.status ] || [ configure -nt config.status ] ; then
        if [[ "$build_modules" == "True" ]]; then
            ./configure $prefix $localstatedir --with-linux=/lib/modules/$(uname -r)/build
        else
            ./configure $prefix $localstatedir
        fi
    fi
    make -j$[$(nproc) + 1]
    sudo make install
    if [[ "$build_modules" == "True" ]]; then
        sudo make INSTALL_MOD_DIR=kernel/net/openvswitch modules_install
        sudo modprobe -r vport_geneve
        sudo modprobe -r openvswitch
        load_module openvswitch
        load_module vport-geneve False
        dmesg | tail
    fi

    cd $_pwd
}

# start_new_ovs() - removes old ovs database, creates a new one and starts ovs
function start_new_ovs () {
    sudo rm -f /etc/openvswitch/conf.db /etc/openvswitch/.conf.db~lock~
    sudo /usr/share/openvswitch/scripts/ovs-ctl start
}

# remove_ovs_packages() - removes old ovs packages from the system
function remove_ovs_packages() {
    for package in openvswitch openvswitch-switch openvswitch-common; do
        if is_package_installed $package; then
            uninstall_package $package
        fi
    done
}