#!/usr/bin/env bash

. /etc/log2ram.conf

if [ -z "$PATH_DISK" ]; then
    PATH_DISK='/var/log'
fi

LOG_NAME='log2ram.log'
NO_RSYNC=${USE_RSYNC#true}

## @fn is_safe()
## @brief Check if hdd log exists
is_safe() {
    [ -d "$HDD_LOG" ] || echo "ERROR: $HDD_LOG/ doesn't exist! Can't sync."
    [ -d "$HDD_LOG" ] || exit 1
}

## @fn journald_logrotate()
## @brief Logrotate the journal if the current RAM_LOG path is part of the journald directory
journald_logrotate() {
    if ! [ -x "$(command -v journalctl)" ] || ! [ "$JOURNALD_AWARE" = true ]; then
        return 1
    fi

    if journalctl --header | grep "File path" | grep "$RAM_LOG" >/dev/null 2>&1; then
        journalctl --rotate
        return 0
    else
        return 1
    fi
}

## @fn sync_to_disk()
## @brief Sync memory back to hard disk
sync_to_disk() {
    is_safe

    optional_params=()

    if journald_logrotate; then
        optional_params+=("--include=journal/*/*@*.journal")
        optional_params+=("--exclude=journal/*/*")
    fi

    if [ -z "${NO_RSYNC}" ] && [ -x "$(command -v rsync)" ]; then
        rsync -aXv --inplace --no-whole-file --delete-after "${optional_params[@]}" "$RAM_LOG"/ "$HDD_LOG"/ 2>&1 |
            tee -a "$LOG2RAM_LOG"
    else
        cp -rfup "$RAM_LOG"/ -T "$HDD_LOG"/ 2>&1 | tee -a "$LOG2RAM_LOG"
    fi
}

## @fn sync_from_disk()
## @brief Sync hard disk to memory
sync_from_disk() {
    is_safe

    TP_SIZE=$SIZE
    if [ "$ZL2R" = true ]; then
        TP_SIZE=$LOG_DISK_SIZE
    fi

    if [ -n "$(du -sh -t "$TP_SIZE" "$HDD_LOG"/ | cut -f1)" ]; then
        echo "ERROR: RAM disk for \"$HDD_LOG/\" too small. Can't sync."
        echo -e "File(s) causing issues\n: $(du -sh -t "$TP_SIZE" "$HDD_LOG"/*)"
        umount -l "$RAM_LOG"/
        umount -l "$HDD_LOG"/
        if [ "$MAIL" = true ]; then
            echo "LOG2RAM : No place on RAM for \"$HDD_LOG/\" anymore, fallback on the disk" | mail -s 'Log2Ram Error' root
        fi
        exit 1
    fi

    if [ -z "${NO_RSYNC}" ] && [ -x "$(command -v rsync)" ]; then
        rsync -aXv --inplace --no-whole-file --delete-after "$HDD_LOG"/ "$RAM_LOG"/ 2>&1 | tee -a "$LOG2RAM_LOG"
    else
        cp -rfup "$HDD_LOG"/ -T "$RAM_LOG"/ 2>&1 | tee -a "$LOG2RAM_LOG"
    fi

}

## @fn wait_for()
## @brief Wait for directory and create test file to make sure the directory exists
## @param param1 path to the directory
wait_for() {
    WAIT_PATH="$1"
    while ! findmnt "$WAIT_PATH" >/dev/null; do
        sleep 0.1
    done

    while [ ! -f "$WAIT_PATH/log2ram.test" ]; do
        touch "$WAIT_PATH/log2ram.test"
        sleep 0.1
    done
    rm "$WAIT_PATH/log2ram.test"
}

## @fn create_zram_log_drive()
## @brief Create zram log device
create_zram_log_drive() {
    # Check Zram Class created
    if [ ! -d "/sys/class/zram-control" ]; then
        modprobe zram
        RAM_DEV='0'
    else
        RAM_DEV=$(cat /sys/class/zram-control/hot_add)
    fi
    echo "$COMP_ALG" >"/sys/block/zram${RAM_DEV}/comp_algorithm"
    echo "$LOG_DISK_SIZE" >"/sys/block/zram${RAM_DEV}/disksize"
    echo "$SIZE" >"/sys/block/zram${RAM_DEV}/mem_limit"
    mke2fs -t ext4 "/dev/zram${RAM_DEV}"
}

case "$1" in
start)
    IFS=';'
    for i in $PATH_DISK; do
        # Skip the path if the folder doesn't exist
        [ ! -d "$i" ] && continue

        PATH_FIRST_PART="${i%/*}"
        PATH_LAST_PART="${i##/*/}"
        RAM_LOG="$i"
        HDD_LOG="${PATH_FIRST_PART}/hdd.${PATH_LAST_PART}"
        LOG2RAM_LOG="${RAM_LOG}/${LOG_NAME}"

        [ -d "$HDD_LOG" ] || mkdir "$HDD_LOG"

        mount --bind "$RAM_LOG"/ "$HDD_LOG"/
        mount --make-private "$HDD_LOG"/
        wait_for "$HDD_LOG"

        if [ "$ZL2R" = true ]; then
            create_zram_log_drive
            mount -t ext4 -o nosuid,noexec,noatime,nodev,user=log2ram "/dev/zram${RAM_DEV}" "$RAM_LOG"/
        else
            mount -t tmpfs -o "nosuid,noexec,noatime,nodev,mode=0755,size=${SIZE}" log2ram "$RAM_LOG"/
        fi
        wait_for "$RAM_LOG"
        sync_from_disk
    done
    exit 0
    ;;

stop)
    IFS=';'
    for i in $PATH_DISK; do
        PATH_FIRST_PART="${i%/*}"
        PATH_LAST_PART="${i##/*/}"
        RAM_LOG="$i"
        HDD_LOG="${PATH_FIRST_PART}/hdd.${PATH_LAST_PART}"
        LOG2RAM_LOG="${RAM_LOG}/${LOG_NAME}"

        sync_to_disk
        #ZRAM_LOG=$(awk '$2 == "/var/log" {print $1}' /proc/mounts)
        #ZRAM_LOG=$(echo ${ZRAM_LOG} | grep -o -E '[0-9]+')
        umount -l "$RAM_LOG"/
        umount -l "$HDD_LOG"/
        # Unsure as even with Root permision denied
        #echo ${ZRAM_LOG} > /sys/class/zram-control/hot_remove
    done
    exit 0
    ;;

write)
    IFS=';'
    for i in $PATH_DISK; do
        PATH_FIRST_PART="${i%/*}"
        PATH_LAST_PART="${i##/*/}"
        RAM_LOG="$i"
        HDD_LOG="${PATH_FIRST_PART}/hdd.${PATH_LAST_PART}"
        LOG2RAM_LOG="${RAM_LOG}/${LOG_NAME}"

        sync_to_disk
    done
    exit 0
    ;;

*)
    echo 'Usage: log2ram {start|stop|write}' >&2
    exit 1
    ;;
esac