#!/bin/bash
# Setup and validate Slack integration for StemeDB alerting
#
# Usage:
#   ./setup-slack.sh                    # Full validation
#   ./setup-slack.sh --validate-only    # Skip test message posting
#   ./setup-slack.sh --dry-run          # Show what would be done

set -euo pipefail

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m' # No Color

# Configuration (override with environment variables)
SLACK_WEBHOOK_CRITICAL="${SLACK_WEBHOOK_CRITICAL:-}"
SLACK_WEBHOOK_WARNING="${SLACK_WEBHOOK_WARNING:-}"
SLACK_WEBHOOK_INFO="${SLACK_WEBHOOK_INFO:-}"
SLACK_CHANNEL_CRITICAL="${SLACK_CHANNEL_CRITICAL:-#stemedb-alerts-critical}"
SLACK_CHANNEL_WARNING="${SLACK_CHANNEL_WARNING:-#stemedb-alerts-warning}"
SLACK_CHANNEL_INFO="${SLACK_CHANNEL_INFO:-#stemedb-alerts-info}"

# Modes
VALIDATE_ONLY=false
DRY_RUN=false

# Parse arguments
for arg in "$@"; do
  case $arg in
    --validate-only)
      VALIDATE_ONLY=true
      shift
      ;;
    --dry-run)
      DRY_RUN=true
      shift
      ;;
    --help)
      echo "Usage: $0 [--validate-only] [--dry-run] [--help]"
      echo ""
      echo "Options:"
      echo "  --validate-only  Skip test message posting"
      echo "  --dry-run        Show what would be done without executing"
      echo "  --help           Show this help message"
      echo ""
      echo "Environment variables:"
      echo "  SLACK_WEBHOOK_CRITICAL   Webhook URL for critical alerts"
      echo "  SLACK_WEBHOOK_WARNING    Webhook URL for warning alerts"
      echo "  SLACK_WEBHOOK_INFO       Webhook URL for info alerts"
      echo "  SLACK_CHANNEL_CRITICAL   Channel name (default: #stemedb-alerts-critical)"
      echo "  SLACK_CHANNEL_WARNING    Channel name (default: #stemedb-alerts-warning)"
      echo "  SLACK_CHANNEL_INFO       Channel name (default: #stemedb-alerts-info)"
      exit 0
      ;;
    *)
      echo "Unknown argument: $arg"
      echo "Use --help for usage information"
      exit 1
      ;;
  esac
done

# Helper functions
log_info() {
  echo -e "${GREEN}[INFO]${NC} $1"
}

log_warn() {
  echo -e "${YELLOW}[WARN]${NC} $1"
}

log_error() {
  echo -e "${RED}[ERROR]${NC} $1"
}

check_dependency() {
  if ! command -v "$1" &> /dev/null; then
    log_error "Required command '$1' not found"
    return 1
  fi
}

# Validation step 1: Check dependencies
validate_dependencies() {
  log_info "Checking dependencies..."

  local missing=0
  for cmd in curl jq; do
    if ! check_dependency "$cmd"; then
      missing=1
    fi
  done

  if [ $missing -eq 1 ]; then
    log_error "Missing required dependencies. Install curl and jq."
    return 1
  fi

  log_info "✓ All dependencies present"
  return 0
}

# Validation step 2: Validate webhook URLs
validate_webhook_urls() {
  log_info "Validating Slack webhook URLs..."

  local failed=0

  # Validate critical webhook
  if [ -z "$SLACK_WEBHOOK_CRITICAL" ]; then
    log_error "SLACK_WEBHOOK_CRITICAL not set"
    log_info "Set it with: export SLACK_WEBHOOK_CRITICAL='https://hooks.slack.com/services/...'"
    failed=1
  elif [[ ! "$SLACK_WEBHOOK_CRITICAL" =~ ^https://hooks\.slack\.com/services/ ]]; then
    log_error "SLACK_WEBHOOK_CRITICAL has invalid format"
    log_info "Expected format: https://hooks.slack.com/services/T00000000/B00000000/XXXXXXXXXXXXXXXXXXXX"
    failed=1
  else
    log_info "✓ Critical webhook URL format valid"
  fi

  # Validate warning webhook
  if [ -z "$SLACK_WEBHOOK_WARNING" ]; then
    log_warn "SLACK_WEBHOOK_WARNING not set (optional)"
  elif [[ ! "$SLACK_WEBHOOK_WARNING" =~ ^https://hooks\.slack\.com/services/ ]]; then
    log_error "SLACK_WEBHOOK_WARNING has invalid format"
    failed=1
  else
    log_info "✓ Warning webhook URL format valid"
  fi

  # Validate info webhook
  if [ -z "$SLACK_WEBHOOK_INFO" ]; then
    log_warn "SLACK_WEBHOOK_INFO not set (optional)"
  elif [[ ! "$SLACK_WEBHOOK_INFO" =~ ^https://hooks\.slack\.com/services/ ]]; then
    log_error "SLACK_WEBHOOK_INFO has invalid format"
    failed=1
  else
    log_info "✓ Info webhook URL format valid"
  fi

  return $failed
}

# Validation step 3: Test message posting
test_message_posting() {
  log_info "Testing message posting to Slack channels..."

  if [ "$DRY_RUN" = true ]; then
    log_info "[DRY RUN] Would send test messages to Slack"
    return 0
  fi

  if [ "$VALIDATE_ONLY" = true ]; then
    log_info "Skipping test messages (--validate-only mode)"
    return 0
  fi

  local failed=0

  # Test critical channel
  if [ -n "$SLACK_WEBHOOK_CRITICAL" ]; then
    log_info "Sending test message to $SLACK_CHANNEL_CRITICAL..."

    local response
    response=$(curl -X POST "$SLACK_WEBHOOK_CRITICAL" \
      -H 'Content-Type: application/json' \
      -d '{
        "channel": "'"$SLACK_CHANNEL_CRITICAL"'",
        "username": "StemeDB Alerts",
        "icon_emoji": ":warning:",
        "attachments": [{
          "color": "danger",
          "title": "🔴 CRITICAL: StemeDB Setup Test",
          "text": "This is a test message from setup-slack.sh. Safe to ignore.",
          "fields": [
            {
              "title": "Severity",
              "value": "CRITICAL",
              "short": true
            },
            {
              "title": "Timestamp",
              "value": "'"$(date -u +%Y-%m-%dT%H:%M:%SZ)"'",
              "short": true
            }
          ],
          "footer": "StemeDB Monitoring"
        }]
      }' 2>&1)

    if [ "$response" = "ok" ]; then
      log_info "✓ Test message sent to $SLACK_CHANNEL_CRITICAL"
    else
      log_error "Failed to send message to $SLACK_CHANNEL_CRITICAL"
      log_error "Response: $response"
      failed=1
    fi
  fi

  # Test warning channel
  if [ -n "$SLACK_WEBHOOK_WARNING" ]; then
    log_info "Sending test message to $SLACK_CHANNEL_WARNING..."

    local response
    response=$(curl -X POST "$SLACK_WEBHOOK_WARNING" \
      -H 'Content-Type: application/json' \
      -d '{
        "channel": "'"$SLACK_CHANNEL_WARNING"'",
        "username": "StemeDB Alerts",
        "icon_emoji": ":warning:",
        "attachments": [{
          "color": "warning",
          "title": "🟡 WARNING: StemeDB Setup Test",
          "text": "This is a test message from setup-slack.sh. Safe to ignore.",
          "fields": [
            {
              "title": "Severity",
              "value": "WARNING",
              "short": true
            },
            {
              "title": "Timestamp",
              "value": "'"$(date -u +%Y-%m-%dT%H:%M:%SZ)"'",
              "short": true
            }
          ],
          "footer": "StemeDB Monitoring"
        }]
      }' 2>&1)

    if [ "$response" = "ok" ]; then
      log_info "✓ Test message sent to $SLACK_CHANNEL_WARNING"
    else
      log_warn "Failed to send message to $SLACK_CHANNEL_WARNING"
      log_warn "Response: $response"
    fi
  fi

  # Test info channel
  if [ -n "$SLACK_WEBHOOK_INFO" ]; then
    log_info "Sending test message to $SLACK_CHANNEL_INFO..."

    local response
    response=$(curl -X POST "$SLACK_WEBHOOK_INFO" \
      -H 'Content-Type: application/json' \
      -d '{
        "channel": "'"$SLACK_CHANNEL_INFO"'",
        "username": "StemeDB Alerts",
        "icon_emoji": ":information_source:",
        "attachments": [{
          "color": "good",
          "title": "ℹ️ INFO: StemeDB Setup Test",
          "text": "This is a test message from setup-slack.sh. Safe to ignore.",
          "fields": [
            {
              "title": "Severity",
              "value": "INFO",
              "short": true
            },
            {
              "title": "Timestamp",
              "value": "'"$(date -u +%Y-%m-%dT%H:%M:%SZ)"'",
              "short": true
            }
          ],
          "footer": "StemeDB Monitoring"
        }]
      }' 2>&1)

    if [ "$response" = "ok" ]; then
      log_info "✓ Test message sent to $SLACK_CHANNEL_INFO"
    else
      log_warn "Failed to send message to $SLACK_CHANNEL_INFO"
      log_warn "Response: $response"
    fi
  fi

  return $failed
}

# Validation step 4: Verify formatting renders correctly
verify_formatting() {
  log_info "Verifying message formatting..."

  if [ "$DRY_RUN" = true ] || [ "$VALIDATE_ONLY" = true ]; then
    log_info "Skipping formatting verification (requires manual check)"
    return 0
  fi

  log_info "Please check Slack channels to verify:"
  log_info "  1. Messages appear in correct channels"
  log_info "  2. Color coding is correct (red=critical, yellow=warning, green=info)"
  log_info "  3. Formatting renders properly (fields, footer, emoji)"
  log_info "  4. Bot icon and username are correct"

  return 0
}

# Validation step 5: Check Alertmanager configuration
verify_alertmanager_config() {
  log_info "Verifying Alertmanager Slack configuration..."

  local alertmanager_config="/etc/prometheus/alertmanager.yml"

  if [ ! -f "$alertmanager_config" ]; then
    log_warn "Alertmanager config not found at $alertmanager_config"
    log_info "Ensure Slack receivers are configured in Alertmanager"
    return 0
  fi

  # Verify Slack receiver is configured
  if grep -q "slack_configs" "$alertmanager_config"; then
    log_info "✓ Slack receivers configured in Alertmanager"

    # Count configured Slack receivers
    local slack_count
    slack_count=$(grep -c "api_url:" "$alertmanager_config" || echo "0")
    log_info "  Found $slack_count Slack webhook(s) configured"

    # Check for channel routing
    if grep -q "channel:" "$alertmanager_config"; then
      log_info "  ✓ Channel routing configured"
    else
      log_warn "  Warning: No explicit channel routing found"
    fi
  else
    log_warn "No Slack receivers found in Alertmanager config"
    log_info "Add Slack receivers to $alertmanager_config"
  fi

  return 0
}

# Main execution
main() {
  echo "========================================="
  echo "StemeDB Slack Setup Validation"
  echo "========================================="
  echo ""

  if [ "$DRY_RUN" = true ]; then
    log_info "Running in DRY RUN mode - no changes will be made"
  fi

  local failed=0

  # Run validation steps
  validate_dependencies || failed=1
  validate_webhook_urls || failed=1
  test_message_posting || failed=1
  verify_formatting || failed=1
  verify_alertmanager_config || failed=1

  echo ""
  echo "========================================="
  if [ $failed -eq 0 ]; then
    log_info "✓ Slack validation PASSED"
    echo "========================================="
    exit 0
  else
    log_error "✗ Slack validation FAILED"
    echo "========================================="
    exit 1
  fi
}

# Run main function
main