#!/bin/bash
# Auto-rollback script for blue-green deployment
# Reverts traffic to the previous healthy stack
#
# Usage: ./auto-rollback.sh [reason]
#   reason: Optional description of why rollback is happening
#
# Exit codes:
#   0 - Rollback successful
#   1 - Rollback failed

set -euo pipefail

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

REASON="${1:-Automatic rollback triggered}"

STATE_FILE="$PROJECT_ROOT/config/deployment/state.json"
SWITCH_SCRIPT="$SCRIPT_DIR/switch-traffic.sh"
HEALTH_SCRIPT="$SCRIPT_DIR/health-check.sh"
NOTIFY_SCRIPT="$SCRIPT_DIR/notify.sh"

echo "========================================"
echo "AUTO-ROLLBACK INITIATED"
echo "Reason: $REASON"
echo "Time: $(date -u +"%Y-%m-%dT%H:%M:%SZ")"
echo "========================================"

# Determine current and rollback stacks
if [[ -f "$STATE_FILE" ]] && command -v jq &> /dev/null; then
  CURRENT_STACK=$(jq -r '.active_stack // "unknown"' "$STATE_FILE")
  ROLLBACK_STACK=$(jq -r '.inactive_stack // "unknown"' "$STATE_FILE")
else
  echo "ERROR: Cannot determine current stack state"
  echo "State file: $STATE_FILE"
  exit 1
fi

if [[ "$CURRENT_STACK" == "unknown" ]] || [[ "$ROLLBACK_STACK" == "unknown" ]]; then
  echo "ERROR: Invalid stack state"
  echo "  Current: $CURRENT_STACK"
  echo "  Rollback target: $ROLLBACK_STACK"
  exit 1
fi

echo ""
echo "Stack Status:"
echo "  Currently active: $CURRENT_STACK"
echo "  Rollback target: $ROLLBACK_STACK"
echo ""

# Verify rollback stack is healthy before switching
echo "Step 1/3: Verifying rollback stack health..."
echo "----------------------------------------"

if [[ -x "$HEALTH_SCRIPT" ]]; then
  if ! "$HEALTH_SCRIPT" "$ROLLBACK_STACK" 30; then
    echo ""
    echo "CRITICAL: Rollback stack ($ROLLBACK_STACK) is NOT healthy!"
    echo "Manual intervention required."
    echo ""
    echo "Troubleshooting steps:"
    echo "  1. Check container logs: docker logs mvp-backend-$ROLLBACK_STACK"
    echo "  2. Check container status: docker ps -a"
    echo "  3. Consider restarting rollback stack"
    echo ""

    # Send critical notification
    if [[ -x "$NOTIFY_SCRIPT" ]]; then
      "$NOTIFY_SCRIPT" "rollback_failed" \
        "Rollback to $ROLLBACK_STACK failed - stack unhealthy. Manual intervention required. Reason: $REASON" \
        || true
    fi

    exit 1
  fi
  echo "  OK: Rollback stack is healthy"
else
  echo "  WARNING: Health check script not found, proceeding anyway"
fi

# Switch traffic to rollback stack
echo ""
echo "Step 2/3: Switching traffic to $ROLLBACK_STACK..."
echo "----------------------------------------"

if [[ -x "$SWITCH_SCRIPT" ]]; then
  if ! "$SWITCH_SCRIPT" "$ROLLBACK_STACK" instant; then
    echo "ERROR: Traffic switch failed"

    if [[ -x "$NOTIFY_SCRIPT" ]]; then
      "$NOTIFY_SCRIPT" "rollback_failed" \
        "Rollback traffic switch failed. Manual intervention required. Reason: $REASON" \
        || true
    fi

    exit 1
  fi
else
  echo "ERROR: Traffic switch script not found: $SWITCH_SCRIPT"
  exit 1
fi

# Update state file with rollback info
echo ""
echo "Step 3/3: Updating deployment state..."
echo "----------------------------------------"

if [[ -f "$STATE_FILE" ]] && command -v jq &> /dev/null; then
  TIMESTAMP=$(date -u +"%Y-%m-%dT%H:%M:%SZ")

  jq --arg stack "$ROLLBACK_STACK" \
     --arg reason "$REASON" \
     --arg ts "$TIMESTAMP" \
     --arg failed "$CURRENT_STACK" \
     '.active_stack = $stack |
      .inactive_stack = $failed |
      .last_rollback = $ts |
      .last_rollback_reason = $reason |
      .rollback_available = false' \
     "$STATE_FILE" > "${STATE_FILE}.tmp" && mv "${STATE_FILE}.tmp" "$STATE_FILE"

  echo "  State updated"
fi

# Send notification
if [[ -x "$NOTIFY_SCRIPT" ]]; then
  echo ""
  echo "Sending rollback notification..."
  "$NOTIFY_SCRIPT" "rollback" \
    "Rollback executed. Traffic switched from $CURRENT_STACK to $ROLLBACK_STACK. Reason: $REASON" \
    || echo "  WARNING: Notification failed"
fi

echo ""
echo "========================================"
echo "ROLLBACK COMPLETE"
echo "========================================"
echo ""
echo "Summary:"
echo "  Previous stack: $CURRENT_STACK (now inactive)"
echo "  Current stack: $ROLLBACK_STACK (now active)"
echo "  Reason: $REASON"
echo ""
echo "Next steps:"
echo "  1. Investigate why $CURRENT_STACK failed"
echo "  2. Check logs: docker logs mvp-backend-$CURRENT_STACK"
echo "  3. Fix issues before next deployment"
echo ""

exit 0