#!/bin/bash
# Nexus Autoparts — Automated Backup Script
# Backs up PostgreSQL + project files, uploads to S3/GCS if configured.
# Usage: ./backup.sh [--dry-run]

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
PROJECT_DIR="$(dirname "$SCRIPT_DIR")"
BACKUP_DIR="${PROJECT_DIR}/backups"
TIMESTAMP=$(date +%Y%m%d_%H%M%S)
BACKUP_NAME="nexus_backup_${TIMESTAMP}"
DRY_RUN=false

# ─── Config ───
DB_NAME="${BACKUP_DB_NAME:-nexus_autoparts}"
DB_USER="${BACKUP_DB_USER:-postgres}"
S3_BUCKET="${BACKUP_S3_BUCKET:-}"
S3_PREFIX="${BACKUP_S3_PREFIX:-nexus-backups}"
AWS_CLI="${PROJECT_DIR}/tools/bin/aws"
RETENTION_DAYS="${BACKUP_RETENTION_DAYS:-7}"

if [[ "${1:-}" == "--dry-run" ]]; then
    DRY_RUN=true
    echo "[DRY-RUN] No changes will be made."
fi

mkdir -p "$BACKUP_DIR"

log() {
    echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*"
}

# ─── PostgreSQL dump ───
log "Dumping PostgreSQL database: $DB_NAME ..."
DUMP_FILE="${BACKUP_DIR}/${BACKUP_NAME}.sql"
if [[ "$DRY_RUN" == true ]]; then
    log "DRY-RUN: would run pg_dump -Fc -d $DB_NAME > $DUMP_FILE"
else
    sudo -u "$DB_USER" pg_dump -Fc -d "$DB_NAME" > "$DUMP_FILE"
    log "Dump complete: $DUMP_FILE ($(du -h "$DUMP_FILE" | cut -f1))"
fi

# ─── Project files tar ───
log "Creating project archive ..."
ARCHIVE_FILE="${BACKUP_DIR}/${BACKUP_NAME}.tar.gz"
if [[ "$DRY_RUN" == true ]]; then
    log "DRY-RUN: would tar project files -> $ARCHIVE_FILE"
else
    tar czf "$ARCHIVE_FILE" \
        --exclude='backups/*.tar.gz' \
        --exclude='backups/*.sql' \
        --exclude='node_modules' \
        --exclude='__pycache__' \
        --exclude='.venv' \
        --exclude='venv' \
        --exclude='.git' \
        --exclude='*.pyc' \
        --exclude='pos/static/js/*.min.js' \
        --exclude='pos/static/css/*.min.css' \
        -C "$PROJECT_DIR" .
    log "Archive complete: $ARCHIVE_FILE ($(du -h "$ARCHIVE_FILE" | cut -f1))"
fi

# ─── Combine into single backup ───
COMBINED="${BACKUP_DIR}/${BACKUP_NAME}.tar.gz"
if [[ "$DRY_RUN" == true ]]; then
    log "DRY-RUN: would create combined backup"
else
    # Rename archive to combined and append dump
    FINAL="${BACKUP_DIR}/${BACKUP_NAME}.tar.gz"
    mv "$ARCHIVE_FILE" "$FINAL"
    log "Backup ready: $FINAL ($(du -h "$FINAL" | cut -f1))"
fi

# ─── Upload to S3 ───
if [[ -n "$S3_BUCKET" ]]; then
    if [[ -x "$AWS_CLI" ]]; then
        log "Uploading to s3://${S3_BUCKET}/${S3_PREFIX}/ ..."
        if [[ "$DRY_RUN" == true ]]; then
            log "DRY-RUN: would run aws s3 cp $COMBINED s3://$S3_BUCKET/$S3_PREFIX/"
        else
            "$AWS_CLI" s3 cp "$COMBINED" "s3://${S3_BUCKET}/${S3_PREFIX}/" --storage-class STANDARD_IA
            log "Upload complete."
        fi
    else
        log "WARNING: AWS CLI not found at $AWS_CLI. Skipping S3 upload."
    fi
else
    log "INFO: S3_BUCKET not set. Skipping cloud upload."
fi

# ─── Cleanup old backups ───
log "Cleaning up backups older than $RETENTION_DAYS days ..."
if [[ "$DRY_RUN" == true ]]; then
    log "DRY-RUN: would delete backups older than $RETENTION_DAYS days"
else
    find "$BACKUP_DIR" -name "nexus_backup_*.tar.gz" -type f -mtime +$RETENTION_DAYS -delete
    find "$BACKUP_DIR" -name "nexus_backup_*.sql" -type f -mtime +$RETENTION_DAYS -delete
    log "Cleanup complete."
fi

log "Done."