#!/bin/bash

###############################################################################
# Database Backup Script for MariaDB
# 
# Features:
# - Dumps all databases from MariaDB
# - Compresses backups with gzip
# - Rotates backups to keep only 7 days of backups
# - Logs all operations with timestamps
# - Handles errors gracefully
###############################################################################

# Use 'set -a' to export all variables (important for password with special chars)
set -a
# Source environment if it exists
if [ -f "/mnt/HC_Volume_103713257/tilbudgivern/backend/.env" ]; then
    source "/mnt/HC_Volume_103713257/tilbudgivern/backend/.env"
fi
set +a

set -euo pipefail

# Configuration
BACKUP_DIR="/mnt/HC_Volume_103713257/tilbudgivern/backups"
LOG_FILE="/mnt/HC_Volume_103713257/tilbudgivern/logs/backups/backup.log"
RETENTION_DAYS=7

# Use environment variables with defaults
MYSQL_USER="${DB_BACKUP_USER:-tilbudgivern_service}"
MYSQL_PASSWORD="${DB_BACKUP_PASSWORD:-}"
MYSQL_HOST="${DB_BACKUP_HOST:-127.0.0.1}"

# Ensure directories exist
mkdir -p "$BACKUP_DIR"
mkdir -p "$(dirname "$LOG_FILE")"

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

# Error handler
error_exit() {
    log "ERROR: $1"
    exit 1
}

# Start backup
log "=========================================="
log "Starting database backup process"
log "=========================================="

# Create timestamp for backup file
TIMESTAMP=$(date '+%Y%m%d_%H%M%S')
BACKUP_FILE="$BACKUP_DIR/mariadb_all_databases_${TIMESTAMP}.sql"
COMPRESSED_FILE="${BACKUP_FILE}.gz"

# Check if mysqldump is available
if ! command -v mysqldump &> /dev/null; then
    error_exit "mysqldump command not found. Please ensure MySQL client is installed."
fi

# Create mysqldump command
MYSQLDUMP_CMD="mysqldump --user=$MYSQL_USER"

if [ -n "$MYSQL_PASSWORD" ]; then
    MYSQLDUMP_CMD="$MYSQLDUMP_CMD --password=$MYSQL_PASSWORD"
fi

MYSQLDUMP_CMD="$MYSQLDUMP_CMD --host=$MYSQL_HOST --all-databases --single-transaction --quick --lock-tables=false"

# Perform backup
log "Dumping all databases from $MYSQL_HOST..."
if $MYSQLDUMP_CMD > "$BACKUP_FILE"; then
    UNCOMPRESSED_SIZE=$(du -h "$BACKUP_FILE" | cut -f1)
    log "Database dump completed successfully. Size: $UNCOMPRESSED_SIZE"
else
    rm -f "$BACKUP_FILE"
    error_exit "Failed to create database dump"
fi

# Compress backup
log "Compressing backup file..."
if gzip "$BACKUP_FILE"; then
    COMPRESSED_SIZE=$(du -h "$COMPRESSED_FILE" | cut -f1)
    log "Backup compressed successfully. Size: $COMPRESSED_SIZE"
    log "Backup saved to: $COMPRESSED_FILE"
else
    error_exit "Failed to compress backup file"
fi

# Rotate backups - keep only 7 most recent
log "Rotating backups (keeping $RETENTION_DAYS days)..."
ROTATION_COUNT=0
while [ $(find "$BACKUP_DIR" -name "mariadb_all_databases_*.sql.gz" -type f | wc -l) -gt $RETENTION_DAYS ]; do
    OLDEST_BACKUP=$(find "$BACKUP_DIR" -name "mariadb_all_databases_*.sql.gz" -type f -printf '%T@ %p\n' | sort -n | head -1 | cut -d' ' -f2-)
    log "Removing old backup: $(basename "$OLDEST_BACKUP")"
    rm -f "$OLDEST_BACKUP"
    ((ROTATION_COUNT++))
done

if [ $ROTATION_COUNT -gt 0 ]; then
    log "Rotated $ROTATION_COUNT backup(s)"
fi

# Display current backups
log "Current backups in system:"
ls -lh "$BACKUP_DIR"/*.gz 2>/dev/null | awk '{print "  " $9 " (" $5 ")"}' | tee -a "$LOG_FILE" || log "No backups found"

# Summary
log "=========================================="
log "Backup process completed successfully"
log "=========================================="

exit 0