#!/bin/bash

set -eu

# If the old cache exists, move it to the new name
function make_new_cache(){
    local OLD_CACHE_BASE=$1
    local CACHE_BASE=$2

    # If the old cache name exists, move it to the new cache name
    if [ -e "$OLD_CACHE_BASE" ] ; then
        if [ ! -e "$CACHE_BASE" ] ; then
            mv -n $OLD_CACHE_BASE $CACHE_BASE
        else
            echo "Not replacing new cache location with old cache"
        fi
    fi
}

# Gets repositories or individual files listed in the a repository file
# and places them in the specified destination path.
# The format of the repository file is one or more lines matching
# <name> <type> <destination> <location> [<ref>]
function get_repos_for_element(){
    local REPO_SOURCES=$1
    local CACHE_URL=$TMP_HOOKS_PATH/bin/cache-url

    local REGEX="^([^ ]+) (git|tar|file|package) ?(/[^ ]+)? ?([^ ]+)? ?([^ ]*)$"

    while read line; do
        # expand variables
        line=$(eval echo $line)

        # ignore blank lines and lines beginning in '#'
        [[ "$line" == \#* ]] || [[ -z "$line" ]] && continue

        if [[ "$line" =~ $REGEX ]]  ; then
            local REPONAME=${BASH_REMATCH[1]}
            local REPOTYPE=${BASH_REMATCH[2]}
            local REPOPATH=${BASH_REMATCH[3]}
            local REPOLOCATION=${BASH_REMATCH[4]}
            local REPO_ORIG_LOCATION=$REPOLOCATION
            local REPOREF=${BASH_REMATCH[5]:-master}

            local REPO_DEST=$TMP_MOUNT_PATH$REPOPATH
            local REPO_SUB_DIRECTORY=$(dirname $REPO_DEST)

            # REPOTYPE can be overridden with DIB_REPOTYPE_{name}
            local REPOTYPE_OVERRIDE=DIB_REPOTYPE_${REPONAME//[^A-Za-z0-9]/_}
            REPOTYPE=${!REPOTYPE_OVERRIDE:-$REPOTYPE}

            # REPOLOCATION can be overridden with DIB_REPOLOCATION_{name}
            local REPOLOCATION_OVERRIDE=DIB_REPOLOCATION_${REPONAME//[^A-Za-z0-9]/_}
            REPOLOCATION=${!REPOLOCATION_OVERRIDE:-$REPOLOCATION}

            # REPOREF can be overridden with DIB_REPOREF_{name}
            local REPOREF_OVERRIDE=DIB_REPOREF_${REPONAME//[^A-Za-z0-9]/_}
            REPOREF=${!REPOREF_OVERRIDE:-$REPOREF}

            # Determine a unique cache path for this repo
            CACHE_NAME=$(echo "${REPOTYPE}_${REPOLOCATION}" | sha1sum | awk '{ print $1 }' )
            OLD_CACHE_PATH=${CACHE_BASE}/${CACHE_NAME}
            # Add the repo name to the sha1sum for readability
            CACHE_NAME=${REPONAME//[^A-Za-z0-9]/_}_${CACHE_NAME}
            CACHE_PATH=${CACHE_BASE}/$CACHE_NAME
            make_new_cache $OLD_CACHE_PATH $CACHE_PATH

            # Return if install type is not source
            local INSTALL_TYPE_VAR=DIB_INSTALLTYPE_${REPONAME//[^A-Za-z0-9]/_}
            local INSTALL_TYPE=${!INSTALL_TYPE_VAR:-source}
            if [ ! $INSTALL_TYPE = "source" ]; then
                echo "$REPONAME install type not set to source"
                continue
            fi

            case $REPOTYPE in
            git)
                if [ -z "${!REPOLOCATION_OVERRIDE:-""}" -a -n "${DIB_GITREPOBASE:-""}" ] ; then
                    # Transform the current repo base to the new one
                    local NEW_REPOLOCATION=$(echo $REPOLOCATION |\
                        sed "s,^[^:]\+://[^/]\+/\(~[^/]\+\)\?\(.*\)$,${DIB_GITREPOBASE}\2,g")
                    echo "Transformed ${REPOLOCATION} to ${NEW_REPOLOCATION}"
                    REPOLOCATION=$NEW_REPOLOCATION
                    # Also update the cache location
                    CACHE_NAME=$(echo "${REPOTYPE}_${REPOLOCATION}" | sha1sum | awk '{ print $1 }' )
                    CACHE_PATH=~/.cache/image-create/repository-sources/$CACHE_NAME
                fi
                sudo mkdir -p $REPO_SUB_DIRECTORY

                if [ ! -e "$CACHE_PATH" ] ; then
                    echo "Caching $REPONAME from $REPOLOCATION in $CACHE_PATH"
                    git clone $REPOLOCATION $CACHE_PATH.tmp
                    mv ${CACHE_PATH}{.tmp,}
                fi

                HAS_REF=$(git --git-dir=$CACHE_PATH/.git name-rev $REPOREF 2>/dev/null || true)
                if [ -z "$DIB_OFFLINE" -o -z "$HAS_REF" ] ; then
                    echo "Updating cache of $REPOLOCATION in $CACHE_PATH with ref $REPOREF"
                    git --git-dir=$CACHE_PATH/.git fetch --update-head-ok $REPOLOCATION ${REPOREF}:${REPOREF}
                fi

                echo "Cloning from $REPONAME cache and applying ref $REPOREF"
                sudo git clone $CACHE_PATH $REPO_DEST
                pushd $REPO_DEST
                sudo git fetch $CACHE_PATH $REPOREF
                sudo git reset --hard FETCH_HEAD
                # Get the reference in use
                git_ref=$(git rev-parse FETCH_HEAD)
                popd

                # Write the reference being used into the source-repositories manifest
                echo "$REPONAME git $REPOPATH $REPOLOCATION $git_ref" >> $GIT_MANIFEST
                ;;
            tar)
                # The top level directory of the tarball mightn't have a fixed name i.e.
                # it could contain version numbers etc... so we write it to a tmpdir
                # the then move the contents into the directory we want it in, this does
                # assume the tarball only contains a single top level directory
                local tmpdir=$(mktemp --tmpdir=$TMP_MOUNT_PATH/tmp -d)
                if [ -n "$CACHE_PATH" ] ; then
                    echo "Caching $REPONAME tarball from $REPOLOCATION in $CACHE_PATH"
                    if [ ! -f "$CACHE_PATH" -o -z "$DIB_OFFLINE" ] ; then
                        $CACHE_URL $REPOLOCATION $CACHE_PATH
                    fi
                    tar -C $tmpdir -xzf $CACHE_PATH
                else
                    echo "Fetching $REPONAME tarball from $REPOLOCATION"
                    curl $REPOLOCATION | tar -C $tmpdir -xzf -
                fi
                sudo mkdir -p $REPO_DEST
                sudo mv $tmpdir/*/* $REPO_DEST
                rm -rf $tmpdir
                ;;
            file)
                sudo mkdir -p $REPO_SUB_DIRECTORY
                if [ -n "$CACHE_PATH" ] ; then
                    echo "Caching $REPONAME file from $REPOLOCATION in $CACHE_PATH"
                    if [ ! -f "$CACHE_PATH" -o -z "$DIB_OFFLINE" ] ; then
                        $CACHE_URL $REPOLOCATION $CACHE_PATH
                    fi
                    sudo cp $CACHE_PATH $REPO_DEST
                else
                    echo "Fetching $REPONAME file from $REPOLOCATION"
                    sudo curl $REPOLOCATION -o $REPO_DEST
                fi
                ;;
            *)
                echo "Unsupported repository type: $REPOTYPE"
                return 1
                ;;
            esac

            # Capture the in-instance repository path for later review / other
            # elements (like a pypi dependency cache).
            echo "$REPOPATH" | sudo dd of=$TMP_MOUNT_PATH/etc/dib-source-repositories oflag=append conv=notrunc

        else
            echo "Couldn't parse '$line' as a source repository"
            return 1
        fi
    done < $REPO_SOURCES
}

CACHE_BASE=~/.cache/image-create/source-repositories
OLD_CACHE_BASE=~/.cache/image-create/repository-sources
make_new_cache $OLD_CACHE_BASE $CACHE_BASE
mkdir -p $CACHE_BASE
# Use the IMAGE_NAME from the calling script, and make it unique with the temporary path
GIT_MANIFEST_NAME=dib-git-manifest-$(basename ${IMAGE_NAME})
GIT_MANIFEST_CACHE_NAME=${GIT_MANIFEST_NAME}_$(dirname ${TMP_MOUNT_PATH##*.})
GIT_MANIFEST=$CACHE_BASE/${GIT_MANIFEST_CACHE_NAME}
rm -f $GIT_MANIFEST

# Get source repositories for the target
for _SOURCEREPO in $(find $TMP_HOOKS_PATH -maxdepth 1 -name "source-repository-*" -not -name '*~'); do
    get_repos_for_element $_SOURCEREPO
done

# Copy the manifest into the image if it exists (there may be no git repositories used)
if [ -e "$GIT_MANIFEST" ] ; then
    sudo cp $GIT_MANIFEST $TMP_MOUNT_PATH/etc/$GIT_MANIFEST_NAME
    sudo mv $GIT_MANIFEST $(dirname ${IMAGE_NAME})/$GIT_MANIFEST_NAME
fi