#!/bin/bash

show_help()
{
cat << end_of_help

 USAGE: $(basename $0) [-h | --help] <[--force] domain1 domain2...>

 $(basename $0) -- Applies Backup Rotation and Retention Policy.
  - Checks backups lifecyle based on MAX_BACKUPS_PER_CHAIN, triggering its archiving when reaches that number of checkpoints
  - Applies retention policy, based on LOCAL|RSYNC_BACKUP_CHAINS_TO_KEEP, keeping as many (and most recent) backup chains on each endpoint, deleting the older ones.
  - When '--force'is passed as the first argument, overrides MAX_BACKUPS_PER_CHAIN and triggers its immediate archiving.

end_of_help
}

if [[ $1 == "-h" || $1 == "--help" ]]; then

    # Show help and exit:
    show_help
    exit

elif [[ $1 == "--force" ]]; then

    # Force the end of lifecycle:
    retention_mode="Forced"
    shift

elif [[ -n $MAX_BACKUPS_PER_CHAIN && $MAX_BACKUPS_PER_CHAIN -gt 0 ]]; then

    # Run normal checks and apply retention policy:
    retention_mode="Normal"
fi

# Load common functions:
source /usr/local/bin/vm-functions

# Processes initial backups list from VMs (passed as arguments):
retention_list=($@)

if [[ -n ${retention_list[@]} ]]; then

    for domain in ${retention_list[@]}; do

        # (Re)Initialize boolean variables:
        local_backup_not_found=""
        end_of_lifecycle=""

        # Display screen divider when processing several backup chains:
        [[ ${#retention_list[@]} -gt 1 ]] \
            && screen_header "-"

        if [[ -d $LOCAL_BACKUP_PATH/$domain \
            && -n $(ls -A $LOCAL_BACKUP_PATH/$domain) \
            && -n $(list_extensions $LOCAL_BACKUP_PATH/$domain | grep -iv log) ]]; then

            echo "$domain: Checking backup chain lifecycle..."

            # Backup path exists, is not empty and has something aside logs. Proceed with check:
            # Retention policy is set (at least, partially) by the user. Retrieve the number of existing checkpoints in the backup chain:
            num_of_backup_checkpoints=$(backup_checkpoints_num $LOCAL_BACKUP_PATH/$domain)

            case $retention_mode in

                Normal) # Will check how many checkpoints will have, marking the end of its lifecycle if cannot be used

                    if [[ $num_of_backup_checkpoints -eq 0 ]]; then

                        # '0' checkpoints means it's a 'copy' backup:
                        end_of_lifecycle=true
                        echo "$domain: Chainless backup made using 'copy' mode. It cannot be used to store incremental backups"

                    elif [[ $num_of_backup_checkpoints -ge $MAX_BACKUPS_PER_CHAIN ]]; then

                        end_of_lifecycle=true
                        echo "$domain: Backup chain has reached the end of its lifecycle and must be rotated ($num_of_backup_checkpoints of $MAX_BACKUPS_PER_CHAIN allowed checkpoints)"

                    else
                        end_of_lifecycle=false
                        echo "$domain: Backup chain currently contains $num_of_backup_checkpoints of $MAX_BACKUPS_PER_CHAIN allowed checkpoints"
                    fi
                ;;

                Forced) # No checks will be performed. Directly end its lifecycle

                    echo "$domain: Backup chain has been forcibly set to end its lifecycle and must be rotated ($num_of_backup_checkpoints of $MAX_BACKUPS_PER_CHAIN allowed checkpoints)"
                    end_of_lifecycle=true
                ;;

                *)  # MAX_BACKUPS_PER_CHAIN is not set, or value is 0:

                    echo "WARNING: $domain: Data retention policy is disabled ($num_of_backup_checkpoints) checkpoints so far)"
                ;;
            esac

            if [[ $end_of_lifecycle == true ]]; then

                # Process local backup chain if it has reached its lifecycle (for whatever reason):
                archive_backup $LOCAL_BACKUP_PATH/$domain $LOCAL_BACKUP_CHAINS_TO_KEEP
            fi

        else
            echo "$domain: No backup found at $LOCAL_BACKUP_PATH"

            # Mark local backup as 'not found' (to perform tasks below):
            local_backup_not_found=true
        fi

        if [[ -n $RSYNC_BACKUP_PATH ]] && [[ $end_of_lifecycle == true || $local_backup_not_found == true ]]; then

            # Process rsync mirror, discerning if located at local or remote (SSH) path:
            [[ $RSYNC_BACKUP_PATH == *@*:/* ]] && archive_command="archive_remote_backup" || archive_command="archive_backup"

            # Also discerning if local backup was not found in first instance,
            # in which case any remote mirror that exists will be archived, but no retention policy applied with old backup chains:
            [[ $local_backup_not_found == true ]] && rsync_retention="" || rsync_retention=$RSYNC_BACKUP_CHAINS_TO_KEEP

            # In order to archive and apply (or not) retention policy on the mirror:
            $archive_command $RSYNC_BACKUP_PATH/$domain $rsync_retention
        fi
    done

    # When multiple backups chains were processed, display that the script has finished:
    [[ ${#retention_list[@]} -gt 1 ]] \
        && echo -e "\n$(basename $0): Finished\n"

else
    echo -e "No flags and/or domain(s) passed as arguments to check backup lifecycle or apply data retention policy\n\nUSAGE: $(basename $0) [-h |--help] <[--force] domain1 domain2...>\n"
fi