#!/bin/bash

CAN_BIND=${CAN_BIND:-1}

# Add a file or a directory to the list of paths to backup
#
# usage: ynh_backup /path/to/stuff
#
# NB : note that this helper does *NOT* perform any copy in itself, it only
# declares stuff to be backuped via a CSV which is later picked up by the core
#
# NB 2 : there is a specific behavior for $data_dir (or childs of $data_dir) and
# /var/log/$app which are *NOT* backedup during safety-backup-before-upgrade,
# OR if the setting "do_not_backup_data" is equals 1 for that app
#
# The rationale is that these directories are usually too heavy to be integrated in every backup
# (think for example about Nextcloud with quite a lot of data, or an app with a lot of media files...)
#
# This is coupled to the fact that $data_dir and the log dir won't be (and
# should NOT) be deleted during remove, unless --purge is used. Hence, if the
# upgrade fails and the script is removed prior to restoring the backup, the
# data/logs are not destroyed.
#
ynh_backup() {

    local target="$1"
    local is_data=false

    # If the path starts with /var/log/$app or $data_dir
    if ([[ -n "${app:-}" ]] && [[ "$target" == "/var/log/$app*" ]]) || ([[ -n "${data_dir:-}" ]] && [[ "$target" == "$data_dir*" ]])
    then
        is_data=true
    fi

    if [[ -n "${app:-}" ]]
    then
        local do_not_backup_data=$(ynh_app_setting_get --key=do_not_backup_data)
    fi

    # If backing up core only (used by ynh_backup_before_upgrade),
    # don't backup big data items
    if [[ "$is_data" == true ]] && ([[ ${do_not_backup_data:-0} -eq 1 ]] || [[ ${BACKUP_CORE_ONLY:-0} -eq 1 ]]); then
        if [ $BACKUP_CORE_ONLY -eq 1 ]; then
            ynh_print_info "$target will not be saved, because 'BACKUP_CORE_ONLY' is set."
        else
            ynh_print_info "$target will not be saved, because 'do_not_backup_data' is set."
        fi
        return 1
    fi

    # ==============================================================================
    # Format correctly source and destination paths
    # ==============================================================================
    # Be sure the source path is not empty
    if [ ! -e "$target" ]; then
        ynh_print_warn "File or folder '${target}' to be backed up does not exist"
        return 1
    fi

    # Transform the source path as an absolute path
    # If it's a dir remove the ending /
    src_path=$(realpath "$target")

    # Initialize the dest path with the source path relative to "/".
    # eg: src_path=/etc/yunohost -> dest_path=etc/yunohost
    dest_path="${src_path#/}"

    # Check if dest_path already exists in tmp archive
    if [[ -e "${dest_path}" ]]; then
        ynh_print_warn "Destination path '${dest_path}' already exist"
        return 1
    fi

    # Add the relative current working directory to the destination path
    local rel_dir="${YNH_CWD#$YNH_BACKUP_DIR}"
    rel_dir="${rel_dir%/}/"
    dest_path="${rel_dir}${dest_path}"
    dest_path="${dest_path#/}"
    # ==============================================================================

    # ==============================================================================
    # Write file to backup into backup_list
    # ==============================================================================
    local src=$(echo "${src_path}" | sed --regexp-extended 's/"/\"\"/g')
    local dest=$(echo "${dest_path}" | sed --regexp-extended 's/"/\"\"/g')
    echo "\"${src}\",\"${dest}\"" >>"${YNH_BACKUP_CSV}"

    # ==============================================================================

    # Create the parent dir of the destination path
    # It's for retro compatibility, some script consider ynh_backup creates this dir
    mkdir --parents $(dirname "$YNH_BACKUP_DIR/${dest_path}")
}

# Return the path in the archive where has been stocked the origin path
#
# [internal]
#
# usage: _get_archive_path ORIGIN_PATH
_get_archive_path() {
    # For security reasons we use csv python library to read the CSV
    python3 -c "
import sys
import csv
with open(sys.argv[1], 'r') as backup_file:
    backup_csv = csv.DictReader(backup_file, fieldnames=['source', 'dest'])
    for row in backup_csv:
        if row['source']==sys.argv[2].strip('\"'):
            print(row['dest'])
            sys.exit(0)
    raise Exception('Original path for %s not found' % sys.argv[2])
    " "${YNH_BACKUP_CSV}" "$1"
    return $?
}

# Restore a file or a directory from the backup archive
#
# usage: ynh_restore /path/to/stuff
#
# examples:
#     ynh_restore "/etc/nginx/conf.d/$domain.d/$app.conf"
#
# If the file or dir to be restored already exists on the system and is lighter
# than 500 Mo, it is backed up in `/var/cache/yunohost/appconfbackup/`.
# Otherwise, the existing file or dir is removed.
#
# if `apps/$app/etc/nginx/conf.d/$domain.d/$app.conf` exists, restore it into
# `/etc/nginx/conf.d/$domain.d/$app.conf`
# otheriwse, search for a match in the csv (eg: conf/nginx.conf) and restore it into
# `/etc/nginx/conf.d/$domain.d/$app.conf`
#
# Requires YunoHost version 2.6.4 or higher.
ynh_restore() {
    target="$1"

    local archive_path="$YNH_CWD${target}"

    # If the path starts with /var/log/$app or $data_dir
    local is_data=false
    if ([[ -n "${app:-}" ]] && [[ "$target" == "/var/log/$app*" ]]) || ([[ -n "${data_dir:-}" ]] && [[ "$target" == "$data_dir*" ]])
    then
        is_data=true
    fi

    # If archive_path doesn't exist, search for a corresponding path in CSV
    if [ ! -d "$archive_path" ] && [ ! -f "$archive_path" ] && [ ! -L "$archive_path" ]; then
        if [[ "$is_data" == true ]]
        then
            ynh_print_info "Skipping $target which doesn't exists in the archive, probably because restoring from a safety-backup-before-upgrade"
            # Assume it's not a big deal, we may be restoring a safety-backup-before-upgrade which doesnt contain those
            return 0
        else
            # (get_archive_path will raise an exception if no match found)
            archive_path="$YNH_BACKUP_DIR/$(_get_archive_path \"$target\")"
        fi
    fi

    # Move the old directory if it already exists
    if [[ -e "${target}" ]]; then
        # Check if the file/dir size is less than 500 Mo
        if [[ $(du --summarize --bytes ${target} | cut --delimiter="/" --fields=1) -le "500000000" ]]; then
            local backup_file="/var/cache/yunohost/appconfbackup/${target}.backup.$(date '+%Y%m%d.%H%M%S')"
            mkdir --parents "$(dirname "$backup_file")"
            mv "${target}" "$backup_file" # Move the current file or directory
        else
            ynh_safe_rm "${target}"
        fi
    fi

    # Restore target into target
    mkdir --parents $(dirname "$target")

    # Do a copy if it's just a mounting point
    if mountpoint --quiet $YNH_BACKUP_DIR; then
        if [[ -d "${archive_path}" ]]; then
            archive_path="${archive_path}/."
            mkdir --parents "$target"
        fi
        cp --archive "$archive_path" "${target}"
    # Do a move if YNH_BACKUP_DIR is already a copy
    else
        mv "$archive_path" "${target}"
    fi
}

# Restore all files that were previously backuped in an app backup script
#
# usage: ynh_restore_everything
#
# Requires YunoHost version 2.6.4 or higher.
ynh_restore_everything() {
    # Deduce the relative path of $YNH_CWD
    local REL_DIR="${YNH_CWD#$YNH_BACKUP_DIR/}"
    REL_DIR="${REL_DIR%/}/"

    # For each destination path begining by $REL_DIR
    cat ${YNH_BACKUP_CSV} | tr --delete $'\r' | grep --only-matching --no-filename --perl-regexp "^\".*\",\"$REL_DIR.*\"$" \
        | while read line; do
            local ARCHIVE_PATH=$(echo "$line" | grep --only-matching --no-filename --perl-regexp "^\".*\",\"$REL_DIR\K.*(?=\"$)")
            ynh_restore "$ARCHIVE_PATH"
        done
}

# Calculate and store a file checksum into the app settings
#
# usage: ynh_store_file_checksum --file=file
# | arg: -f, --file=    - The file on which the checksum will performed, then stored.
#
# $app should be defined when calling this helper
#
# Requires YunoHost version 2.6.4 or higher.
ynh_store_file_checksum() {
    # ============ Argument parsing =============
    local -A args_array=([f]=file= [u]=update_only)
    local file
    local update_only
    update_only="${update_only:-0}"
    ynh_handle_getopts_args "$@"
    # ===========================================

    local checksum_setting_name=checksum_${file//[\/ ]/_} # Replace all '/' and ' ' by '_'

    # If update only, we don't save the new checksum if no old checksum exist
    if [ $update_only -eq 1 ]; then
        local checksum_value=$(ynh_app_setting_get --key=$checksum_setting_name)
        if [ -z "${checksum_value}" ]; then
            unset backup_file_checksum
            return 0
        fi
    fi

    ynh_app_setting_set --key=$checksum_setting_name --value=$(md5sum "$file" | cut --delimiter=' ' --fields=1)

    if [ ${PACKAGE_CHECK_EXEC:-0} -eq 1 ]; then
        # Using a base64 is in fact more reversible than "replace / and space by _" ... So we can in fact obtain the original file path in an easy reliable way ...
        local file_path_base64=$(echo "$file" | base64 -w0)
        mkdir -p /var/cache/yunohost/appconfbackup/
        cat $file > /var/cache/yunohost/appconfbackup/original_${file_path_base64}
    fi

    # If backup_file_checksum isn't empty, ynh_backup_if_checksum_is_different has made a backup
    if [ -n "${backup_file_checksum-}" ]; then
        # Print the diff between the previous file and the new one.
        # diff return 1 if the files are different, so the || true
        diff --report-identical-files --unified --color=always $backup_file_checksum $file >&2 || true
    fi
    # Unset the variable, so it wouldn't trig a ynh_store_file_checksum without a ynh_backup_if_checksum_is_different before it.
    unset backup_file_checksum
}

# Verify the checksum and backup the file if it's different
#
# usage: ynh_backup_if_checksum_is_different --file=file
# | arg: -f, --file=    - The file on which the checksum test will be perfomed.
# | ret: the name of a backup file, or nothing
#
# This helper is primarily meant to allow to easily backup personalised/manually
# modified config files.
#
# Requires YunoHost version 2.6.4 or higher.
ynh_backup_if_checksum_is_different() {
    # ============ Argument parsing =============
    local -A args_array=([f]=file=)
    local file
    ynh_handle_getopts_args "$@"
    # ===========================================

    local checksum_setting_name=checksum_${file//[\/ ]/_} # Replace all '/' and ' ' by '_'
    local checksum_value=$(ynh_app_setting_get --key=$checksum_setting_name)
    # backup_file_checksum isn't declare as local, so it can be reuse by ynh_store_file_checksum
    backup_file_checksum=""
    if [ -n "$checksum_value" ]; then                                                     # Proceed only if a value was stored into the app settings
        if [ -e $file ] && ! echo "$checksum_value $file" | md5sum --check --status; then # If the checksum is now different

            backup_file_checksum="/var/cache/yunohost/appconfbackup/$file.backup.$(date '+%Y%m%d.%H%M%S')"
            mkdir --parents "$(dirname "$backup_file_checksum")"
            cp --archive "$file" "$backup_file_checksum" # Backup the current file
            ynh_print_warn "File $file has been manually modified since the installation or last upgrade. So it has been duplicated in $backup_file_checksum"
            echo "$backup_file_checksum" # Return the name of the backup file
            if [ ${PACKAGE_CHECK_EXEC:-0} -eq 1 ]; then
                local file_path_base64=$(echo "$file" | base64 -w0)
                if test -e /var/cache/yunohost/appconfbackup/original_${file_path_base64}
                then
                    ynh_print_warn "Diff with the original file:"
                    diff --report-identical-files --unified --color=always /var/cache/yunohost/appconfbackup/original_${file_path_base64} $file >&2 || true
                fi
            fi
        fi
    fi
}

# Delete a file checksum from the app settings
#
# usage: ynh_delete_file_checksum --file=file
# | arg: -f, --file=    - The file for which the checksum will be deleted
#
# $app should be defined when calling this helper
#
# Requires YunoHost version 3.3.1 or higher.
ynh_delete_file_checksum() {
    # ============ Argument parsing =============
    local -A args_array=([f]=file=)
    local file
    ynh_handle_getopts_args "$@"
    # ===========================================

    local checksum_setting_name=checksum_${file//[\/ ]/_} # Replace all '/' and ' ' by '_'
    ynh_app_setting_delete --key=$checksum_setting_name
}
