#! /usr/bin/env bash

# script.sh - utilitary functions.
# Copyright (c) 2022 ge <https://nixhacks.net/>
#
# This program is free software: you can redistribute it and/or modify
# it under the terms of the GNU General Public License as published by
# the Free Software Foundation, either version 3 of the License, or
# (at your option) any later version.
#
# This program is distributed in the hope that it will be useful,
# but WITHOUT ANY WARRANTY; without even the implied warranty of
# MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
# GNU General Public License for more details.
#
# You should have received a copy of the GNU General Public License
# along with this program.  If not, see <https://www.gnu.org/licenses/>.

validate_sources() {
    # Check sources array.
    #
    # Usage: validate_sources ARRAY

    # Allowed URI schemes: file, mysql postgres, sqlite
    # No required schemes.

    local array=("$@")
    local scheme=

    for uri in "${array[@]}"; do
        scheme="${uri%%:*}"
        case "$scheme" in
            file|mysql|postgres|sqlite) : ;; # do nothing, this is OK
            *) echo "Error: Unsupported URI scheme: $scheme" >&2; exit 1;;
        esac
    done
}

validate_targets() {
    # Check targets array and set local_target variable.
    #
    # Usage: validate_targets ARRAY

    # Allowed URI schemes: file, ftp, sftp, rsync, s3, swift, sj, dav, davs
    # Required schemes (one or more times): file

    local array=("$@")
    local scheme=
    local file_targets=()

    for uri in "${array[@]}"; do
        scheme="${uri%%:*}"
        case "$scheme" in
            file|ftp|sftp|rsync|s3|swift|sj|dav|davs)
                if [[ "$scheme" == file ]]; then
                    file_targets+=("$uri")
                fi
            ;;
            *) echo "Error: Unsupported URI scheme: $scheme" >&2; exit 1;;
        esac
    done

    if [ "${#file_targets[@]}" -eq 0 ]; then
        echo "Error: 'file' scheme is not set in targets." \
            "You must provide one or more targets with 'file' scheme." >&2
        exit 1
    else
        # Set local_target. This variable contains path to save local backups.
        # Files to additional targets will be coped from this directory.
        local_target="${file_targets[0]}"
    fi
}

source_script() {
    # Safely as possible source backup script.
    #
    # Usage: source_script SCRIPT

    local script="$1"

    if ! test -f "$script"; then
        echo "Error: No such file: $script" >&2; exit 1
    fi

    # Dry run script, check syntax. See set(1p)
    if ! bash -n "$script"; then
        echo Error: Please check your syntax >&2; exit 1
    fi

    # Source script
    . "$@"

    # Check required variables
    if [[ "$sources" ]]; then
        validate_sources "${sources[@]}"
    else
        echo Error: sources array is not set >&2; exit 1
    fi

    if [[ "$targets" ]]; then
        validate_targets "${targets[@]}"
    else
        echo Error: targets array is not set >&2; exit 1
    fi
}

is_function_set() {
    # Test function is set or not. Return exit code.
    # Useful with 'if' statement.
    #
    # Usage: is_function_set FUNCTION

    declare -F -- "$1" > /dev/null
}