#!/bin/sh

set -e

REPOSITORY=https://github.com/descartes-underwriting/devops-technical-test-data.git
BRANCH=main
DATA_DIR=$(pwd)/data
# max number of commit to backup
MAX_NUM=0
# logs!
VERBOSE=0
# ignore tracking. Can be useful to fill missing commits
# if 0 (and -i not used), will continue where it stopped.
IGNORE_TRACK=0

while getopts ":r:b:d:vxn:hi" opt
do
    case ${opt} in
        r)
            REPOSITORY=${OPTARG}
            ;;
        b)
            BRANCH=${OPTARG}
            ;;
        d)
            DATA_DIR=${OPTARG}
            if [[ "${DATA_DIR}" != /* ]]
            then
                # I want an absolute directory
                DATA_DIR=$(pwd)/${DATA_DIR}
            fi
            ;;
        i)
            IGNORE_TRACK=1
            ;;
        n)
            MAX_NUM=${OPTARG}
            ;;
        v)
            VERBOSE=1
            ;;
        x)
            set -x
            ;;
        h)
            echo "Usage: $0 [-r <repository url>] [-b <branch>] [-d <absolute path dest>] [-n <num>] [-v] [-x] [-h]"
            echo "Ex: $0 -r $REPOSITORY -b $BRANCH -d $DATA_DIR"
            exit 0
            ;;
        ?)
            echo "Invalid option -${OPTARG}"
            exit 1
            ;;
    esac
done

IFS="
"

GIT=git
GIT_OPTS=(-c core.quotepath=false)

if test ! -d ${DATA_DIR}
then
    mkdir -p ${DATA_DIR}
fi

TMPDIR=$(mktemp -d)
cd ${TMPDIR}

git clone ${REPOSITORY} && cd ./*

CURRENT_COMMIT=""
if test -s ${DATA_DIR}/.track -a ${IGNORE_TRACK} -eq 0
then
    CURRENT_COMMIT=$(cat ${DATA_DIR}/.track)..
fi

# List all commit sha, from older to newer; 
COMMIT_SHAS=$($GIT ${GIT_OPTS[@]} log --reverse --pretty=format:"%H" remotes/origin/${BRANCH} ${CURRENT_COMMIT})

NUM_ADDED=0

for COMMIT_SHA in ${COMMIT_SHAS}
do
    if test -d ${DATA_DIR}/${COMMIT_SHA}
    then
        # commit already backup; skipping
        continue
    fi

    echo "new commit: ${COMMIT_SHA}"

    # There are malformed files names that are creating complex filenames to parse.
    # Those malformed filenames are double quotes, so to remove quotes, -c core.quotepath=false
    # and -z are used. sed 's/\x0/\n/g' is replacing the null byte by a return to line
    FILES=$($GIT ${GIT_OPTS[@]} show --pretty= --name-only -z ${COMMIT_SHA} | sed 's/\x0/\n/g')

    if test -z "${FILES}"
    then
        # merge commit, etc. There is no file here.
        echo "No file was found in commit ${COMMIT_SHA}"
    fi

    TARGET_BACKUP_SHA=${DATA_DIR}/${COMMIT_SHA}
    mkdir -p ${TARGET_BACKUP_SHA}

    for FILE in ${FILES}
    do
        TARGET_DIR=$(dirname ${FILE})
        mkdir -p ${TARGET_BACKUP_SHA}/${TARGET_DIR}

        if test ${VERBOSE} -eq 1
        then
            echo "Writing ${TARGET_BACKUP_SHA}/${FILE}"
        fi

        # Retrieve file state (Added, Modified, Deleted)
        # Using basic regex as we want to avoid checking '()' or other complex regex patterns.
        # This is suboptimal and error prone. But it passes the full backup :-)
        STATE=$(${GIT} ${GIT_OPTS[@]} show --name-status --pretty= ${COMMIT_SHA} | grep -G "^..${FILE}\$" | cut -f1)

        if test "${STATE}" != "D"
        then
            # ${FILE} contains path/to/file
            $GIT ${GIT_OPTS[@]} show ${COMMIT_SHA}:${FILE} > ${TARGET_BACKUP_SHA}/${FILE}
        else
            echo "Skipping ${FILE} as file was deleted in this commit"
        fi
    done

    # if ${TARGET_BACKUP_SHA} is empty, keep track it was "backuped"
    if test -z "$(ls -A ${TARGET_BACKUP_SHA})"
    then
        echo "Folder ${TARGET_BACKUP_SHA} is empty. Marking it to keep as it in the backup"
        touch ${TARGET_BACKUP_SHA}/.gitkeep
    fi

    NUM_ADDED=$((NUM_ADDED + 1))

    echo -n ${COMMIT_SHA} > ${DATA_DIR}/.track

    if test ${NUM_ADDED} -eq ${MAX_NUM}
    then
        echo "Max commit to backup reached; stopping."
        break
    fi
done

echo "done: ${NUM_ADDED} commits"