#!/usr/bin/bash

HOME=$(pwd)
MODELSFILE="models.yml"

while IFS= read -r line; do
    PAT_VERSION=$(echo "${line}" | cut -f 1 -d ' ')
    PAT_BUILD=$(echo "${line}" | cut -f 2 -d ' ')
    MODEL=$(echo "${line}" | cut -f 3 -d ' ')
    BUILD=$(echo "${line}" | cut -f 4 -d ' ')
    CACHE_PATH="${HOME}/cache"
    RAMDISK_PATH="${CACHE_PATH}/ramdisk"
    PAT_FILE="${MODEL}_${BUILD}.pat"
    PAT_PATH="${CACHE_PATH}/dl/${PAT_FILE}"
    EXTRACTOR_PATH="${CACHE_PATH}/extractor"
    EXTRACTOR_BIN="syno_extract_system_patch"
    UNTAR_PAT_PATH="${CACHE_PATH}/${MODEL}/${BUILD}"
    DSMPATH="${HOME}/dsm"
    DESTINATION="${DSMPATH}/${MODEL}/${BUILD}"
    FILESPATH="${HOME}/files"
    DESTINATIONFILES="${FILESPATH}/${MODEL}/${BUILD}"
    if [ ! -f "${DESTINATIONFILES}/dsm.tar" ] || [ ! -f "${DESTINATION}" ]; then
        PAT_MODEL="$(echo "${MODEL}" | sed 's/ /%20/')"
        echo "${PAT_MODEL} ${VERSION} ${BUILD}"
        
        PAT_LINK="${PAT_VERSION}/${PAT_BUILD}/DSM_${PAT_MODEL}_${BUILD}.pat"
        PAT_URL="https://global.synologydownload.com/download/DSM/release/${PAT_LINK}"

        speed_a=$(ping -c 1 -W 5 global.synologydownload.com | awk '/time=/ {print $7}' | cut -d '=' -f 2)
        speed_b=$(ping -c 1 -W 5 global.download.synology.com | awk '/time=/ {print $7}' | cut -d '=' -f 2)
        fastest=$(echo -e "global.synologydownload.com ${speed_a:-999}\nglobal.download.synology.com ${speed_b:-999}" | sort -k2rn | head -1 | awk '{print $1}')
        
        mirror=$(echo ${PAT_URL} | sed 's|^http[s]*://\([^/]*\).*|\1|')
        echo "$(printf "Based on the current network situation, switch to %s mirror for download." "${fastest}")"
        PAT_URL=$(echo ${PAT_URL} | sed "s/${mirror}/${fastest}/")
        
        mkdir -p "${CACHE_PATH}/dl"

        if [ ! -f "${PAT_PATH}" ]; then
            echo "Downloading ${PAT_FILE}"
            # Discover remote file size
            STATUS=$(curl -k -w "%{http_code}" -L "${PAT_URL}" -o "${PAT_PATH}" --progress-bar)
            if [ $? -ne 0 -o ${STATUS} -ne 200 ]; then
                rm "${PAT_PATH}"
                echo "Error downloading"
            fi
            if [ -f "${PAT_PATH}" ]; then
                
                mkdir -p "${DESTINATION}"
                mkdir -p "${DESTINATIONFILES}"

                echo -n "Checking hash of pat: "
                HASH=$(md5sum ${PAT_PATH} | awk '{print$1}')
                echo "OK"
                echo "${HASH}" >"${DESTINATION}/pat_hash"
                echo "${PAT_URL}" >"${DESTINATION}/pat_url"

                rm -rf "${UNTAR_PAT_PATH}"
                mkdir -p "${UNTAR_PAT_PATH}"
                echo -n "Disassembling ${PAT_FILE}: "

                header=$(od -bcN2 ${PAT_PATH} | head -1 | awk '{print $3}')
                case ${header} in
                    105)
                    echo "Uncompressed tar"
                    isencrypted="no"
                    ;;
                    213)
                    echo "Compressed tar"
                    isencrypted="no"
                    ;;
                    255)
                    echo "Encrypted"
                    isencrypted="yes"
                    ;;
                    *)
                    echo -e "Could not determine if pat file is encrypted or not, maybe corrupted, try again!"
                    ;;
                esac

                if [ "${isencrypted}" = "yes" ]; then
                    # Check existance of extractor
                    if [ -f "${EXTRACTOR_PATH}/${EXTRACTOR_BIN}" ]; then
                        echo "Extractor cached."
                    fi
                    # Uses the extractor to untar pat file
                    echo "Extracting..."
                    LD_LIBRARY_PATH="${EXTRACTOR_PATH}" "${EXTRACTOR_PATH}/${EXTRACTOR_BIN}" "${PAT_PATH}" "${UNTAR_PAT_PATH}"
                else
                    echo "Extracting..."
                    tar -xf "${PAT_PATH}" -C "${UNTAR_PAT_PATH}"
                    if [ $? -ne 0 ]; then
                        echo "Error extracting"
                    fi
                fi

                echo -n "Checking hash of zImage: "
                HASH=$(sha256sum ${UNTAR_PAT_PATH}/zImage | awk '{print$1}')
                echo "OK"
                echo "${HASH}" >"${DESTINATION}/zImage_hash"

                echo -n "Checking hash of ramdisk: "
                HASH=$(sha256sum ${UNTAR_PAT_PATH}/rd.gz | awk '{print$1}')
                echo "OK"
                echo "${HASH}" >"${DESTINATION}/ramdisk_hash"

                echo -n "Copying files: "
                cp "${UNTAR_PAT_PATH}/grub_cksum.syno" "${DESTINATION}"
                cp "${UNTAR_PAT_PATH}/GRUB_VER"        "${DESTINATION}"
                cp "${UNTAR_PAT_PATH}/grub_cksum.syno" "${DESTINATION}"
                cp "${UNTAR_PAT_PATH}/GRUB_VER"        "${DESTINATION}"
                cp "${UNTAR_PAT_PATH}/zImage"          "${DESTINATION}"
                cp "${UNTAR_PAT_PATH}/rd.gz"           "${DESTINATION}"
                cd "${DESTINATION}"
                tar -cf "${DESTINATIONFILES}/dsm.tar" .
                rm -f "${PAT_PATH}"
                rm -rf "${UNTAR_PAT_PATH}"
                echo "DSM extract complete: ${MODEL}_${BUILD}"
            else
                echo "DSM extract Error: ${MODEL}_${BUILD}"
            fi
        fi
        cd ${HOME}
    fi
done < ${MODELSFILE}

rm -rf "${CACHE_PATH}/dl"