#!/usr/bin/env bash
# /home/spuser/PassKeeper/scripts/restore_db.sh
#
# Restore a PassKeeper MySQL backup created by backup_db.sh.
#
# SAFETY FEATURES:
#   - Requires explicit confirmation before overwriting the live database.
#   - Creates a pre-restore safety dump of the current DB before touching it.
#   - Verifies the backup file is a valid gzip before proceeding.
#   - Stops the PassKeeper service before restore, restarts it after.
#   - Runs flask db upgrade after restore to ensure the schema is current.
#
# Usage:
#   bash scripts/restore_db.sh /path/to/passkeeper_20260101_020000.sql.gz
#
# Dry-run (verify only, no changes):
#   DRY_RUN=1 bash scripts/restore_db.sh /path/to/backup.sql.gz

set -euo pipefail

# ── Configuration ──────────────────────────────────────────────────────────────
SCRIPT_DIR="$(dirname "$(realpath "$0")")"
PROJECT_DIR="$(realpath "$SCRIPT_DIR/..")"
ENV_FILE="$PROJECT_DIR/.env"
SERVICE_NAME="${PASSKEEPER_SERVICE:-passkeeper}"
BACKUP_DIR="${BACKUP_DIR:-/home/spuser/backups/passkeeper}"
LOG_FILE="${BACKUP_DIR}/restore.log"
DRY_RUN="${DRY_RUN:-0}"

# ── Helpers ────────────────────────────────────────────────────────────────────
log()  { echo "[$(date '+%Y-%m-%d %H:%M:%S')] $*" | tee -a "$LOG_FILE"; }
die()  { log "ERROR $*"; exit 1; }
info() { log "INFO  $*"; }

# ── Argument check ─────────────────────────────────────────────────────────────
[[ $# -lt 1 ]] && die "Usage: $0 <backup_file.sql.gz>"
BACKUP_FILE="$(realpath "$1")"
[[ -f "$BACKUP_FILE" ]] || die "Backup file not found: $BACKUP_FILE"

# ── Load .env ─────────────────────────────────────────────────────────────────
[[ -f "$ENV_FILE" ]] || die ".env file not found at $ENV_FILE"
set -o allexport
# shellcheck disable=SC1090
source "$ENV_FILE"
set +o allexport

DB_HOST="${MYSQL_HOST:-127.0.0.1}"
DB_PORT="${MYSQL_PORT:-3306}"
DB_USER="${MYSQL_USER:-passkeeper}"
DB_PASS="${MYSQL_PASSWORD}"
DB_NAME="${MYSQL_DB:-passkeeper}"

mkdir -p "$BACKUP_DIR"

info "=== PassKeeper database restore ==="
info "Backup file : $BACKUP_FILE"
info "Target DB   : $DB_NAME @ $DB_HOST:$DB_PORT"
info "Service     : $SERVICE_NAME"
[[ "$DRY_RUN" == "1" ]] && info "MODE        : DRY RUN — no changes will be made"

# ── Validate backup file ───────────────────────────────────────────────────────
info "Validating backup file integrity…"
if ! gzip -t "$BACKUP_FILE" 2>/dev/null; then
    die "Backup file failed gzip integrity check: $BACKUP_FILE"
fi
BACKUP_SIZE="$(du -sh "$BACKUP_FILE" | cut -f1)"
info "Backup size : $BACKUP_SIZE — gzip OK"

# ── Confirmation ───────────────────────────────────────────────────────────────
if [[ "$DRY_RUN" != "1" ]]; then
    echo ""
    echo "  ⚠️  WARNING: This will OVERWRITE the live database '$DB_NAME'."
    echo "  All current data will be replaced with the contents of:"
    echo "  $BACKUP_FILE"
    echo ""
    read -r -p "  Type 'yes' to continue: " CONFIRM
    [[ "$CONFIRM" == "yes" ]] || { info "Restore cancelled by user."; exit 0; }
fi

[[ "$DRY_RUN" == "1" ]] && { info "Dry run complete — backup file is valid."; exit 0; }

# ── Pre-restore safety dump ────────────────────────────────────────────────────
SAFETY_TIMESTAMP="$(date +%Y%m%d_%H%M%S)"
SAFETY_FILE="${BACKUP_DIR}/pre_restore_safety_${SAFETY_TIMESTAMP}.sql.gz"
info "Creating pre-restore safety dump → $SAFETY_FILE"
MYSQL_PWD="$DB_PASS" mysqldump \
    --host="$DB_HOST" \
    --port="$DB_PORT" \
    --user="$DB_USER" \
    --single-transaction \
    --no-tablespaces \
    "$DB_NAME" \
    | gzip -9 > "$SAFETY_FILE" \
    || die "Safety dump failed — aborting restore. Database is unchanged."
info "Safety dump complete: $(du -sh "$SAFETY_FILE" | cut -f1)"

# ── Stop service ───────────────────────────────────────────────────────────────
info "Stopping $SERVICE_NAME…"
sudo systemctl stop "$SERVICE_NAME" || die "Failed to stop $SERVICE_NAME"
info "$SERVICE_NAME stopped"

RESTORE_OK=0

# ── Restore ────────────────────────────────────────────────────────────────────
info "Restoring database from backup…"
if MYSQL_PWD="$DB_PASS" gunzip -c "$BACKUP_FILE" | mysql \
    --host="$DB_HOST" \
    --port="$DB_PORT" \
    --user="$DB_USER" \
    "$DB_NAME"; then
    info "Database restore complete"
    RESTORE_OK=1
else
    log "ERROR Database restore failed — attempting to roll back from safety dump"
    if MYSQL_PWD="$DB_PASS" gunzip -c "$SAFETY_FILE" | mysql \
        --host="$DB_HOST" \
        --port="$DB_PORT" \
        --user="$DB_USER" \
        "$DB_NAME"; then
        log "WARN  Rolled back to pre-restore state from $SAFETY_FILE"
    else
        log "ERROR Rollback also failed — database may be in an inconsistent state"
        log "ERROR Manual recovery required. Safety dump: $SAFETY_FILE"
    fi
fi

# ── Run migrations ─────────────────────────────────────────────────────────────
if [[ "$RESTORE_OK" == "1" ]]; then
    info "Running flask db upgrade to ensure schema is current…"
    cd "$PROJECT_DIR"
    if source .venv/bin/activate 2>/dev/null; then
        flask db upgrade && info "flask db upgrade OK" || \
            log "WARN  flask db upgrade failed — check migrations manually"
        deactivate 2>/dev/null || true
    else
        log "WARN  Could not activate .venv — skipping flask db upgrade"
        log "WARN  Run 'flask db upgrade' manually before restarting the service"
    fi
fi

# ── Restart service ────────────────────────────────────────────────────────────
info "Starting $SERVICE_NAME…"
sudo systemctl start "$SERVICE_NAME" && info "$SERVICE_NAME started" || \
    die "$SERVICE_NAME failed to start — check 'journalctl -u $SERVICE_NAME -n 50'"

# ── Summary ────────────────────────────────────────────────────────────────────
echo ""
if [[ "$RESTORE_OK" == "1" ]]; then
    info "=== Restore finished successfully ==="
    info "Restored from : $BACKUP_FILE"
    info "Safety dump   : $SAFETY_FILE (kept for 24 h — delete manually when satisfied)"
else
    die "=== Restore FAILED — see log for details: $LOG_FILE ==="
fi