#!/bin/bash
# Maintenance mode migration script
# Enables maintenance mode, runs migrations, then restores service
#
# Usage: ./maintenance-migrate.sh [backup]
#   backup: If set, creates a database backup before migration
#
# This script is for BREAKING migrations that require downtime.
# Non-breaking migrations run automatically on container start.
#
# Exit codes:
#   0 - Migration successful
#   1 - Migration failed (maintenance mode will remain active)

set -euo pipefail

SCRIPT_DIR="$(cd "$(dirname "${BASH_SOURCE[0]}")" && pwd)"
PROJECT_ROOT="$(cd "$SCRIPT_DIR/../.." && pwd)"

CREATE_BACKUP="${1:-}"

COMPOSE_FILE="$PROJECT_ROOT/docker-compose.yml"
COMPOSE_BLUE_GREEN="$PROJECT_ROOT/docker-compose.blue-green.yml"
STATE_FILE="$PROJECT_ROOT/config/deployment/state.json"
NOTIFY_SCRIPT="$SCRIPT_DIR/notify.sh"
TRAEFIK_CONFIG="$PROJECT_ROOT/config/traefik/dynamic/blue-green.yml"
BACKUP_DIR="$PROJECT_ROOT/data/backups"

echo "========================================"
echo "MAINTENANCE MODE MIGRATION"
echo "Time: $(date -u +"%Y-%m-%dT%H:%M:%SZ")"
echo "========================================"

# Determine active stack
if [[ -f "$STATE_FILE" ]] && command -v jq &> /dev/null; then
  ACTIVE_STACK=$(jq -r '.active_stack // "blue"' "$STATE_FILE")
else
  ACTIVE_STACK="blue"
fi

BACKEND_CONTAINER="mvp-backend-$ACTIVE_STACK"

echo ""
echo "Configuration:"
echo "  Active stack: $ACTIVE_STACK"
echo "  Backend container: $BACKEND_CONTAINER"
echo "  Create backup: ${CREATE_BACKUP:-no}"
echo ""

# Step 1: Send maintenance notification
echo "Step 1/6: Sending maintenance notification..."
echo "----------------------------------------"

if [[ -x "$NOTIFY_SCRIPT" ]]; then
  "$NOTIFY_SCRIPT" "maintenance_start" "Starting maintenance window for database migration" || true
fi
echo "  OK"

# Step 2: Enable maintenance mode
echo ""
echo "Step 2/6: Enabling maintenance mode..."
echo "----------------------------------------"

# Update state file
if [[ -f "$STATE_FILE" ]] && command -v jq &> /dev/null; then
  jq '.maintenance_mode = true' "$STATE_FILE" > "${STATE_FILE}.tmp" && mv "${STATE_FILE}.tmp" "$STATE_FILE"
fi

# Stop traffic to both stacks (weight 0)
echo "  Stopping traffic to application stacks..."

# Set both stacks to weight 0 - Traefik will return 503
sed -i.bak -E "s/(name: mvp-frontend-blue-svc[[:space:]]+weight:)[[:space:]]+[0-9]+/\1 0/" "$TRAEFIK_CONFIG"
sed -i.bak -E "s/(name: mvp-frontend-green-svc[[:space:]]+weight:)[[:space:]]+[0-9]+/\1 0/" "$TRAEFIK_CONFIG"
sed -i.bak -E "s/(name: mvp-backend-blue-svc[[:space:]]+weight:)[[:space:]]+[0-9]+/\1 0/" "$TRAEFIK_CONFIG"
sed -i.bak -E "s/(name: mvp-backend-green-svc[[:space:]]+weight:)[[:space:]]+[0-9]+/\1 0/" "$TRAEFIK_CONFIG"
rm -f "${TRAEFIK_CONFIG}.bak"

# Wait for Traefik to pick up changes
sleep 3
echo "  OK: Maintenance mode active"

# Step 3: Create database backup (if requested)
if [[ -n "$CREATE_BACKUP" ]]; then
  echo ""
  echo "Step 3/6: Creating database backup..."
  echo "----------------------------------------"

  mkdir -p "$BACKUP_DIR"
  BACKUP_FILE="$BACKUP_DIR/pre-migration-$(date +%Y%m%d-%H%M%S).sql"

  if docker exec mvp-postgres pg_dump -U postgres motovaultpro > "$BACKUP_FILE"; then
    echo "  OK: Backup created: $BACKUP_FILE"
    ls -lh "$BACKUP_FILE"
  else
    echo "  ERROR: Backup failed"
    echo ""
    echo "Aborting migration. Restoring traffic..."

    # Restore traffic
    if [[ "$ACTIVE_STACK" == "blue" ]]; then
      sed -i -E "s/(name: mvp-frontend-blue-svc[[:space:]]+weight:)[[:space:]]+[0-9]+/\1 100/" "$TRAEFIK_CONFIG"
      sed -i -E "s/(name: mvp-backend-blue-svc[[:space:]]+weight:)[[:space:]]+[0-9]+/\1 100/" "$TRAEFIK_CONFIG"
    else
      sed -i -E "s/(name: mvp-frontend-green-svc[[:space:]]+weight:)[[:space:]]+[0-9]+/\1 100/" "$TRAEFIK_CONFIG"
      sed -i -E "s/(name: mvp-backend-green-svc[[:space:]]+weight:)[[:space:]]+[0-9]+/\1 100/" "$TRAEFIK_CONFIG"
    fi

    if [[ -f "$STATE_FILE" ]] && command -v jq &> /dev/null; then
      jq '.maintenance_mode = false' "$STATE_FILE" > "${STATE_FILE}.tmp" && mv "${STATE_FILE}.tmp" "$STATE_FILE"
    fi

    exit 1
  fi
else
  echo ""
  echo "Step 3/6: Skipping backup (not requested)..."
  echo "----------------------------------------"
  echo "  OK"
fi

# Step 4: Run migrations
echo ""
echo "Step 4/6: Running database migrations..."
echo "----------------------------------------"

# Flush Redis cache before migration
echo "  Flushing Redis cache..."
docker exec mvp-redis redis-cli FLUSHALL > /dev/null 2>&1 || true

# Run migrations
echo "  Running migrations..."
if docker exec "$BACKEND_CONTAINER" npm run migrate; then
  echo "  OK: Migrations completed"
else
  echo "  ERROR: Migration failed"
  echo ""
  echo "Migration failed. Maintenance mode remains active."
  echo "To restore:"
  echo "  1. Fix migration issues"
  echo "  2. Re-run migrations: docker exec $BACKEND_CONTAINER npm run migrate"
  echo "  3. Run: $0 to retry, or manually restore traffic"

  if [[ -x "$NOTIFY_SCRIPT" ]]; then
    "$NOTIFY_SCRIPT" "failure" "Database migration failed during maintenance window. Manual intervention required." || true
  fi

  exit 1
fi

# Step 5: Restart backend containers
echo ""
echo "Step 5/6: Restarting backend containers..."
echo "----------------------------------------"

# Restart both backends to pick up any schema changes
docker restart mvp-backend-blue mvp-backend-green 2>/dev/null || true

# Wait for backends to be healthy
echo "  Waiting for backends to be healthy..."
sleep 10

for container in mvp-backend-blue mvp-backend-green; do
  for i in {1..12}; do
    health=$(docker inspect --format='{{.State.Health.Status}}' "$container" 2>/dev/null || echo "unknown")
    if [[ "$health" == "healthy" ]]; then
      echo "  OK: $container is healthy"
      break
    fi
    if [[ $i -eq 12 ]]; then
      echo "  WARNING: $container health check timeout"
    fi
    sleep 5
  done
done

# Step 6: Disable maintenance mode
echo ""
echo "Step 6/6: Restoring traffic..."
echo "----------------------------------------"

# Restore traffic to active stack
if [[ "$ACTIVE_STACK" == "blue" ]]; then
  sed -i -E "s/(name: mvp-frontend-blue-svc[[:space:]]+weight:)[[:space:]]+[0-9]+/\1 100/" "$TRAEFIK_CONFIG"
  sed -i -E "s/(name: mvp-backend-blue-svc[[:space:]]+weight:)[[:space:]]+[0-9]+/\1 100/" "$TRAEFIK_CONFIG"
else
  sed -i -E "s/(name: mvp-frontend-green-svc[[:space:]]+weight:)[[:space:]]+[0-9]+/\1 100/" "$TRAEFIK_CONFIG"
  sed -i -E "s/(name: mvp-backend-green-svc[[:space:]]+weight:)[[:space:]]+[0-9]+/\1 100/" "$TRAEFIK_CONFIG"
fi

# Update state file
if [[ -f "$STATE_FILE" ]] && command -v jq &> /dev/null; then
  TIMESTAMP=$(date -u +"%Y-%m-%dT%H:%M:%SZ")
  jq --arg ts "$TIMESTAMP" '.maintenance_mode = false | .last_migration = $ts' "$STATE_FILE" > "${STATE_FILE}.tmp" && mv "${STATE_FILE}.tmp" "$STATE_FILE"
fi

# Wait for Traefik to pick up changes
sleep 3
echo "  OK: Traffic restored"

# Send completion notification
if [[ -x "$NOTIFY_SCRIPT" ]]; then
  "$NOTIFY_SCRIPT" "maintenance_end" "Maintenance window complete. Database migration successful." || true
fi

echo ""
echo "========================================"
echo "MAINTENANCE MIGRATION COMPLETE"
echo "========================================"
echo ""
echo "Summary:"
echo "  - Migrations: Successful"
echo "  - Active stack: $ACTIVE_STACK"
echo "  - Maintenance mode: Disabled"
if [[ -n "$CREATE_BACKUP" ]]; then
  echo "  - Backup: $BACKUP_FILE"
fi
echo ""

exit 0