#!/bin/bash

# Description
# This script performs a backup of all folders in /srv
# For folders corresponding to active Docker containers,
# containers are stopped during backup then restarted
# Containers listed in EXCLUDED_CONTAINERS are ignored
# Backups are kept for 7 days

# Configuration
SRV_DIR="/srv"
BACKUP_DEST="/root/docker-backup"
RETENTION_DAYS=7
LOG_FILE="/root/docker-backup.log"

# List of containers to exclude from backup (space separated)
# Example: EXCLUDED_CONTAINERS="traefik mysql-prod redis-cache"
EXCLUDED_CONTAINERS=""

# Logging function
log_message() {
    echo "$(date '+%Y-%m-%d %H:%M:%S') - $1" | tee -a "$LOG_FILE"
}

# Check if destination directory exists
if [ ! -d "$BACKUP_DEST" ]; then
    log_message "Creating destination directory $BACKUP_DEST"
    mkdir -p "$BACKUP_DEST"
fi

# Check available disk space (at least 1GB)
available_space=$(df "$BACKUP_DEST" | awk 'NR==2 {print $4}')
if [ "$available_space" -lt 1048576 ]; then
    log_message "WARNING: Low disk space (less than 1GB available)"
fi

log_message "Starting Docker backup"

# Counters for statistics
success_count=0
error_count=0
docker_stopped=()
docker_errors=()

# Function to backup a directory
backup_directory() {
    local source_dir="$1"
    local folder_name="$2"
    
    if [ ! -e "$source_dir" ]; then
        log_message "WARNING: $source_dir does not exist, skipped"
        ((error_count++))
        return 1
    fi
    
    # Create destination folder for this service
    local dest_folder="$BACKUP_DEST/$folder_name"
    mkdir -p "$dest_folder"
    
    local filename="${folder_name}_$(date +%Y-%m-%d_%H-%M-%S).tar.gz"
    local filepath="$dest_folder/$filename"
    
    log_message "Backing up $source_dir to $folder_name/$filename"
    
    # Create the archive
    if tar -czf "$filepath" -C "$(dirname "$source_dir")" "$(basename "$source_dir")" 2>/dev/null; then
        # Create SHA-256 checksum file
        sha256sum "$filepath" > "$filepath.sha256"
        file_size=$(du -h "$filepath" | cut -f1)
        log_message "SUCCESS: $filename created ($file_size) - Checksum generated"
        ((success_count++))
        return 0
    else
        log_message "ERROR: Unable to create archive for $source_dir"
        ((error_count++))
        return 1
    fi
}

# Function to check if Docker is installed
is_docker_available() {
    command -v docker >/dev/null 2>&1
}

# Function to check if a container is excluded
is_container_excluded() {
    local container_name="$1"
    if [ -n "$EXCLUDED_CONTAINERS" ]; then
        for excluded in $EXCLUDED_CONTAINERS; do
            if [ "$container_name" = "$excluded" ]; then
                return 0
            fi
        done
    fi
    return 1
}

# Function to check if a Docker container exists and is running
is_container_running() {
    local container_name="$1"
    if is_docker_available; then
        docker ps --format "table {{.Names}}" | grep -q "^${container_name}$" 2>/dev/null
    else
        return 1
    fi
}

# Function to stop a Docker container
stop_container() {
    local container_name="$1"
    log_message "Stopping Docker container: $container_name"
    if docker stop "$container_name" >/dev/null 2>&1; then
        log_message "Container $container_name stopped successfully"
        docker_stopped+=("$container_name")
        return 0
    else
        log_message "ERROR: Unable to stop container $container_name"
        docker_errors+=("$container_name")
        return 1
    fi
}

# Function to start a Docker container
start_container() {
    local container_name="$1"
    log_message "Starting Docker container: $container_name"
    if docker start "$container_name" >/dev/null 2>&1; then
        log_message "Container $container_name started successfully"
        return 0
    else
        log_message "ERROR: Unable to start container $container_name"
        return 1
    fi
}

# Check if Docker is available
if ! is_docker_available; then
    log_message "WARNING: Docker is not installed or accessible"
fi

# Backup directories in /srv
log_message "=== DOCKER SERVICES BACKUP ==="
if [ -d "$SRV_DIR" ]; then
    # Loop through all folders in /srv
    for srv_folder in "$SRV_DIR"/*; do
        if [ -d "$srv_folder" ]; then
            folder_name=$(basename "$srv_folder")
            
            # Check if the container is in the exclusion list
            if is_container_excluded "$folder_name"; then
                log_message "EXCLUSION: Container $folder_name skipped (in exclusion list)"
                continue
            fi
            
            # Check if a Docker container with this name exists and is running
            if is_container_running "$folder_name"; then
                log_message "Active Docker container detected: $folder_name"
                
                # Stop the container
                if stop_container "$folder_name"; then
                    # Wait a bit to ensure the container is completely stopped
                    sleep 5
                    
                    # Perform the backup
                    backup_directory "$srv_folder" "$folder_name"
                    
                    # Restart the container
                    start_container "$folder_name"
                else
                    log_message "WARNING: Backing up $folder_name without stopping container (risk of inconsistency)"
                    backup_directory "$srv_folder" "$folder_name"
                fi
            else
                # No corresponding Docker container, normal backup
                log_message "Service without active container: $folder_name"
                backup_directory "$srv_folder" "$folder_name"
            fi
        fi
    done
else
    log_message "ERROR: Directory $SRV_DIR does not exist"
    exit 1
fi

# Verification and generation of checksums for all archives
log_message "=== CHECKSUM VERIFICATION AND GENERATION ==="
archives_without_checksum=0
archives_with_checksum=0

find "$BACKUP_DEST" -name "*.tar.gz" -type f | while read -r archive_file; do
    checksum_file="${archive_file}.sha256"
    if [ ! -f "$checksum_file" ]; then
        log_message "Generating missing checksum for $(basename "$archive_file")"
        sha256sum "$archive_file" > "$checksum_file"
        ((archives_without_checksum++))
    else
        ((archives_with_checksum++))
    fi
done

# Final archive count
total_archives=$(find "$BACKUP_DEST" -name "*.tar.gz" -type f | wc -l)
missing_checksums=$(find "$BACKUP_DEST" -name "*.tar.gz" -type f | while read -r archive; do [ ! -f "${archive}.sha256" ] && echo "$archive"; done | wc -l)

log_message "Archives found: $total_archives"
if [ "$missing_checksums" -eq 0 ]; then
    log_message "SUCCESS: All archives have a checksum file"
else
    log_message "WARNING: $missing_checksums archives without checksum"
fi

# Cleanup of old backups
log_message "=== OLD BACKUPS CLEANUP ==="
for service_dir in "$BACKUP_DEST"/*/; do
    if [ -d "$service_dir" ]; then
        service_name=$(basename "$service_dir")
        log_message "Removing backups older than $RETENTION_DAYS days for $service_name"
        
        # Find obsolete files (archives and checksums separately)
        deleted_files_tar=$(find "$service_dir" -type f -name "*.tar.gz" -mtime +$RETENTION_DAYS -print 2>/dev/null)
        deleted_files_sha=$(find "$service_dir" -type f -name "*.sha256" -mtime +$RETENTION_DAYS -print 2>/dev/null)
        
        if [ -n "$deleted_files_tar" ] || [ -n "$deleted_files_sha" ]; then
            # Remove and log archives
            if [ -n "$deleted_files_tar" ]; then
                echo "$deleted_files_tar" | while read -r file; do
                    log_message "Removing: $service_name/$(basename "$file")"
                done
                find "$service_dir" -type f -name "*.tar.gz" -mtime +$RETENTION_DAYS -delete 2>/dev/null
            fi
            # Remove and log checksums
            if [ -n "$deleted_files_sha" ]; then
                echo "$deleted_files_sha" | while read -r file; do
                    log_message "Removing: $service_name/$(basename "$file")"
                done
                find "$service_dir" -type f -name "*.sha256" -mtime +$RETENTION_DAYS -delete 2>/dev/null
            fi
        else
            log_message "No obsolete files to remove for $service_name"
        fi
    fi
done

# Restart containers that failed to restart
if [ ${#docker_errors[@]} -gt 0 ]; then
    log_message "=== RETRY STARTING CONTAINERS IN ERROR ==="
    for container in "${docker_errors[@]}"; do
        start_container "$container"
    done
fi

# Final statistics
log_message "=== BACKUP SUMMARY ==="
log_message "Successful backups: $success_count"
log_message "Errors: $error_count"
if [ ${#docker_stopped[@]} -gt 0 ]; then
    log_message "Docker containers managed: ${docker_stopped[*]}"
fi
if [ ${#docker_errors[@]} -gt 0 ]; then
    log_message "Docker containers in error: ${docker_errors[*]}"
fi
log_message "Backup completed"

# Exit code based on errors
if [ $error_count -gt 0 ] || [ ${#docker_errors[@]} -gt 0 ]; then
    exit 1
else
    exit 0
fi