#!/usr/bin/env bash
set -euo pipefail

# Rollback Script
# Sprint: CI/CD Enhancement - Deployment Safety
#
# Purpose: Execute rollback to a previous version
# Usage:
#   ./rollback.sh --environment <env> --version <ver> --services <json> --reason <text>
#
# Exit codes:
#   0 - Rollback successful
#   1 - General error
#   2 - Invalid arguments
#   3 - Deployment failed
#   4 - Health check failed

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

# Colors for output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
BLUE='\033[0;34m'
NC='\033[0m'

log_info() {
    echo -e "${GREEN}[INFO]${NC} $*"
}

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

log_error() {
    echo -e "${RED}[ERROR]${NC} $*" >&2
}

log_step() {
    echo -e "${BLUE}[STEP]${NC} $*"
}

usage() {
    cat << EOF
Usage: $(basename "$0") [OPTIONS]

Execute rollback to a previous version.

Options:
  --environment <env>    Target environment (staging|production)
  --version <version>    Target version to rollback to
  --services <json>      JSON array of services to rollback
  --reason <text>        Reason for rollback
  --dry-run              Show what would be done without executing
  --help, -h             Show this help message

Examples:
  $(basename "$0") --environment staging --version 1.2.3 --services '["scanner"]' --reason "Bug fix"
  $(basename "$0") --environment production --version 1.2.0 --services '["authority","scanner"]' --reason "Hotfix rollback"

Exit codes:
  0  Rollback successful
  1  General error
  2  Invalid arguments
  3  Deployment failed
  4  Health check failed
EOF
}

# Default values
ENVIRONMENT=""
VERSION=""
SERVICES=""
REASON=""
DRY_RUN=false

# Parse arguments
while [[ $# -gt 0 ]]; do
    case "$1" in
        --environment)
            ENVIRONMENT="$2"
            shift 2
            ;;
        --version)
            VERSION="$2"
            shift 2
            ;;
        --services)
            SERVICES="$2"
            shift 2
            ;;
        --reason)
            REASON="$2"
            shift 2
            ;;
        --dry-run)
            DRY_RUN=true
            shift
            ;;
        --help|-h)
            usage
            exit 0
            ;;
        *)
            log_error "Unknown option: $1"
            usage
            exit 2
            ;;
    esac
done

# Validate required arguments
if [[ -z "$ENVIRONMENT" ]] || [[ -z "$VERSION" ]] || [[ -z "$SERVICES" ]]; then
    log_error "Missing required arguments"
    usage
    exit 2
fi

# Validate environment
if [[ "$ENVIRONMENT" != "staging" ]] && [[ "$ENVIRONMENT" != "production" ]]; then
    log_error "Invalid environment: $ENVIRONMENT (must be staging or production)"
    exit 2
fi

# Validate services JSON
if ! echo "$SERVICES" | jq empty 2>/dev/null; then
    log_error "Invalid services JSON: $SERVICES"
    exit 2
fi

log_info "Starting rollback process"
log_info "  Environment: $ENVIRONMENT"
log_info "  Version: $VERSION"
log_info "  Services: $SERVICES"
log_info "  Reason: $REASON"
log_info "  Dry run: $DRY_RUN"

# Record start time
START_TIME=$(date +%s)

# Rollback each service
FAILED_SERVICES=()
SUCCESSFUL_SERVICES=()

echo "$SERVICES" | jq -r '.[]' | while read -r service; do
    log_step "Rolling back $service to $VERSION..."

    if [[ "$DRY_RUN" == "true" ]]; then
        log_info "  [DRY RUN] Would rollback $service"
        continue
    fi

    # Determine deployment method
    HELM_RELEASE="stellaops-${service}"
    NAMESPACE="stellaops-${ENVIRONMENT}"

    # Check if Helm release exists
    if helm status "$HELM_RELEASE" -n "$NAMESPACE" >/dev/null 2>&1; then
        log_info "  Using Helm rollback for $service"

        # Get revision for target version
        REVISION=$(helm history "$HELM_RELEASE" -n "$NAMESPACE" --output json | \
            jq -r --arg ver "$VERSION" '.[] | select(.app_version == $ver) | .revision' | tail -1)

        if [[ -n "$REVISION" ]]; then
            if helm rollback "$HELM_RELEASE" "$REVISION" -n "$NAMESPACE" --wait --timeout 5m; then
                log_info "  Successfully rolled back $service to revision $REVISION"
                SUCCESSFUL_SERVICES+=("$service")
            else
                log_error "  Failed to rollback $service"
                FAILED_SERVICES+=("$service")
            fi
        else
            log_warn "  No Helm revision found for version $VERSION"
            log_info "  Attempting deployment with specific version..."

            # Try to deploy specific version
            IMAGE_TAG="${VERSION}"
            VALUES_FILE="${REPO_ROOT}/devops/helm/values-${ENVIRONMENT}.yaml"

            if helm upgrade "$HELM_RELEASE" "${REPO_ROOT}/devops/helm/stellaops" \
                -n "$NAMESPACE" \
                --set "services.${service}.image.tag=${IMAGE_TAG}" \
                -f "$VALUES_FILE" \
                --wait --timeout 5m 2>/dev/null; then
                log_info "  Deployed $service with version $VERSION"
                SUCCESSFUL_SERVICES+=("$service")
            else
                log_error "  Failed to deploy $service with version $VERSION"
                FAILED_SERVICES+=("$service")
            fi
        fi
    else
        log_warn "  No Helm release found for $service"
        log_info "  Attempting kubectl rollout undo..."

        DEPLOYMENT="stellaops-${service}"

        if kubectl rollout undo deployment/"$DEPLOYMENT" -n "$NAMESPACE" 2>/dev/null; then
            log_info "  Rolled back deployment $DEPLOYMENT"
            SUCCESSFUL_SERVICES+=("$service")
        else
            log_error "  Failed to rollback deployment $DEPLOYMENT"
            FAILED_SERVICES+=("$service")
        fi
    fi
done

# Calculate duration
END_TIME=$(date +%s)
DURATION=$((END_TIME - START_TIME))

# Summary
echo ""
log_info "Rollback completed in ${DURATION}s"
log_info "  Successful: ${#SUCCESSFUL_SERVICES[@]}"
log_info "  Failed: ${#FAILED_SERVICES[@]}"

if [[ ${#FAILED_SERVICES[@]} -gt 0 ]]; then
    log_error "Failed services: ${FAILED_SERVICES[*]}"
    exit 3
fi

log_info "Rollback successful"
exit 0