#!/bin/bash

set -e  # Exit on error
trap 'log_message "ERROR: An error occurred. Exiting."' ERR

# Global Configurations
LOG_FILE="/var/log/backup_script.log"
DEFAULT_BACKUP_COUNT=5

# Validate required variables
validate_inputs() {
    : "${ENV_NAME:?ENV_NAME not set or empty. Please provide an environment name.}"
    : "${RESTIC_PASSWORD:?RESTIC_PASSWORD not set}"
    : "${APP_PATH:?APP_PATH not set}"
    
    # Dynamically set the backup path
    BACKUP_REPO_PATH="/mnt/backups/${ENV_NAME}"
    [ -d "$BACKUP_REPO_PATH" ] || mkdir -p "$BACKUP_REPO_PATH"
    export BACKUP_REPO_PATH
}

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

# Ensure Restic is installed
install_restic() {
    if ! which restic &>/dev/null; then
        log_message "Restic not found. Installing..."
        if which dnf &>/dev/null; then
            dnf install -y epel-release && dnf install -y restic
        elif which yum &>/dev/null; then
            yum install -y restic
        else
            log_message "ERROR: Unsupported package manager."
            exit 1
        fi
    fi
    log_message "Restic is installed."
}

# Initialize or validate repository
check_backup_repo() {
    if ! restic -r "$BACKUP_REPO_PATH" snapshots &>/dev/null; then
        log_message "Initializing new Restic repository..."
        restic -r "$BACKUP_REPO_PATH" init
    else
        log_message "Restic repository validated."
    fi
}

# Backup a given path
perform_backup() {
    local path="$1"
    local tag="$2"
    local exclude="$3"

    log_message "Backing up $path with tag $tag..."
    restic -r "$BACKUP_REPO_PATH" backup "$path" --tag "$tag" $exclude
    log_message "Backup for $path completed."
}

# Rotate snapshots
rotate_snapshots() {
    local keep_count="${1:-$DEFAULT_BACKUP_COUNT}"
    log_message "Rotating snapshots. Keeping the last $keep_count..."
    restic -r "$BACKUP_REPO_PATH" forget --keep-last "$keep_count" --prune
    log_message "Snapshot rotation completed."
}

# Backup database
backup_database() {
    log_message "Starting database backup..."
    local db_dump
    db_dump=$(mktemp)

    # Generate DB dump
    mysqldump -h "$DB_HOST" -u "$DB_USER" -p"$DB_PASSWORD" "$DB_NAME" > "$db_dump"
    perform_backup "$db_dump" "database-backup"
    rm -f "$db_dump"
    log_message "Database backup completed."
}

# Main entry point
case "$1" in
    backup)
        validate_inputs
        install_restic
        check_backup_repo
        perform_backup "$APP_PATH/wp-content" "wp-core" "--exclude $APP_PATH/wp-content/uploads"
        perform_backup "$APP_PATH/wp-content/uploads" "wp-uploads"
        backup_database
        rotate_snapshots
        ;;
    check_repo)
        validate_inputs
        check_backup_repo
        ;;
    rotate_snapshots)
        rotate_snapshots "$2"
        ;;
    *)
        echo "Usage: $0 {backup|check_repo|rotate_snapshots}"
        exit 1
        ;;
esac