#!/bin/bash
# Foxhunt Deployment Rollback Script
# Wave 5 W5-4: Safe rollback to previous deployment revision
#
# Usage: ./scripts/deployment/rollback.sh [service] [revision]
#   service: api-gateway|trading-service|backtesting-service|ml-training-service|trading-agent-service|all
#   revision: revision number (optional, defaults to previous)

set -euo pipefail

# Color output
RED='\033[0;31m'
GREEN='\033[0;32m'
YELLOW='\033[1;33m'
NC='\033[0m'

# Configuration
SERVICE="${1:-all}"
REVISION="${2:-0}"  # 0 = previous revision
NAMESPACE="foxhunt"
TIMEOUT=600

# Service list
ALL_SERVICES=(
    "api-gateway"
    "trading-service"
    "backtesting-service"
    "ml-training-service"
    "trading-agent-service"
)

echo -e "${YELLOW}========================================${NC}"
echo -e "${YELLOW}Foxhunt Deployment Rollback${NC}"
echo -e "${YELLOW}Service: ${SERVICE}${NC}"
echo -e "${YELLOW}Namespace: ${NAMESPACE}${NC}"
echo -e "${YELLOW}========================================${NC}"

# Function: Show deployment history
show_history() {
    local service=$1
    echo -e "\n${YELLOW}Deployment history for ${service}:${NC}"
    kubectl rollout history deployment/"${service}" --namespace="${NAMESPACE}" || true
}

# Function: Rollback a service
rollback_service() {
    local service=$1
    local revision=$2

    echo -e "\n${YELLOW}Rolling back ${service}...${NC}"

    # Show current history
    show_history "${service}"

    # Confirm rollback
    if [ "${REVISION}" == "0" ]; then
        echo -e "${RED}This will rollback ${service} to the previous revision.${NC}"
    else
        echo -e "${RED}This will rollback ${service} to revision ${revision}.${NC}"
    fi

    read -p "Are you sure? (y/N) " -n 1 -r
    echo
    if [[ ! $REPLY =~ ^[Yy]$ ]]; then
        echo "Rollback cancelled."
        return
    fi

    # Perform rollback
    if [ "${revision}" == "0" ]; then
        kubectl rollout undo deployment/"${service}" --namespace="${NAMESPACE}"
    else
        kubectl rollout undo deployment/"${service}" --namespace="${NAMESPACE}" --to-revision="${revision}"
    fi

    # Wait for rollout
    echo "Waiting for rollback to complete..."
    if kubectl rollout status deployment/"${service}" \
        --namespace="${NAMESPACE}" \
        --timeout="${TIMEOUT}s"; then
        echo -e "${GREEN}✓ ${service} rolled back successfully${NC}"
    else
        echo -e "${RED}✗ ${service} rollback failed${NC}"

        # Show pod logs
        echo "Recent pod logs:"
        kubectl logs -l app="${service}" --namespace="${NAMESPACE}" --tail=50 || true

        # Show events
        echo -e "\nRecent events:"
        kubectl get events --namespace="${NAMESPACE}" --field-selector involvedObject.name="${service}" --sort-by='.lastTimestamp' | tail -20

        exit 1
    fi

    # Verify health
    verify_health "${service}"
}

# Function: Verify service health after rollback
verify_health() {
    local service=$1

    echo -e "\n${YELLOW}Verifying ${service} health...${NC}"

    # Get pod name
    POD=$(kubectl get pods -l app="${service}" \
        --namespace="${NAMESPACE}" \
        -o jsonpath='{.items[0].metadata.name}' 2>/dev/null || echo "")

    if [ -z "$POD" ]; then
        echo -e "${RED}✗ No pods found for ${service}${NC}"
        return 1
    fi

    # Get health port
    case $service in
        api-gateway)
            HEALTH_PORT=8080
            HEALTH_PATH="/health/liveness"
            ;;
        trading-service)
            HEALTH_PORT=8081
            HEALTH_PATH="/health"
            ;;
        backtesting-service)
            HEALTH_PORT=8082
            HEALTH_PATH="/health"
            ;;
        ml-training-service)
            HEALTH_PORT=8095
            HEALTH_PATH="/health"
            ;;
        trading-agent-service)
            HEALTH_PORT=8083
            HEALTH_PATH="/health"
            ;;
    esac

    # Check health
    sleep 5  # Give service time to stabilize
    if kubectl exec -it "$POD" --namespace="${NAMESPACE}" -- \
        curl -f "http://localhost:${HEALTH_PORT}${HEALTH_PATH}" &> /dev/null; then
        echo -e "${GREEN}✓ ${service} is healthy after rollback${NC}"
    else
        echo -e "${RED}✗ ${service} health check failed after rollback${NC}"
        return 1
    fi
}

# Function: Rollback all services
rollback_all() {
    echo -e "\n${RED}WARNING: This will rollback ALL services!${NC}"
    read -p "Are you ABSOLUTELY sure? Type 'YES' to confirm: " -r
    echo

    if [[ ! $REPLY == "YES" ]]; then
        echo "Rollback cancelled."
        exit 0
    fi

    # Rollback in reverse order (agent -> ml -> backtesting -> trading -> gateway)
    for service in "${ALL_SERVICES[@]}"; do
        rollback_service "${service}" "${REVISION}"
    done

    echo -e "\n${GREEN}All services rolled back successfully${NC}"
}

# Function: Show summary
show_summary() {
    echo -e "\n${GREEN}========================================${NC}"
    echo -e "${GREEN}Rollback Summary${NC}"
    echo -e "${GREEN}========================================${NC}"

    echo -e "\nPods:"
    kubectl get pods --namespace="${NAMESPACE}" -o wide

    echo -e "\nDeployments:"
    kubectl get deployments --namespace="${NAMESPACE}"

    echo -e "\n${GREEN}Rollback completed!${NC}"
}

# Main rollback flow
main() {
    # Check kubectl
    if ! command -v kubectl &> /dev/null; then
        echo -e "${RED}Error: kubectl not found${NC}"
        exit 1
    fi

    # Perform rollback
    if [ "${SERVICE}" == "all" ]; then
        rollback_all
    else
        # Validate service name
        if [[ ! " ${ALL_SERVICES[@]} " =~ " ${SERVICE} " ]]; then
            echo -e "${RED}Error: Invalid service name '${SERVICE}'${NC}"
            echo "Valid services: ${ALL_SERVICES[*]} or 'all'"
            exit 1
        fi

        rollback_service "${SERVICE}" "${REVISION}"
    fi

    show_summary
}

# Run main function
main