package services

import (
	"context"
	"fmt"
	"strings"
	"time"

	appsv1 "k8s.io/api/apps/v1"
	metav1 "k8s.io/apimachinery/pkg/apis/meta/v1"
	"k8s.io/apimachinery/pkg/util/intstr"
	"lokistack/models"
)

const ingressNamespace = "ingress-nginx"
const ingressControllerName = "ingress-nginx-controller"

// The field names are shared with the JSON parser on the Loki query page.
const ingressAccessFormat = `{"time":"$time_iso8601","remote_addr":"$remote_addr","host":"$host","http_host":"$http_host","request":"$request","method":"$request_method","uri":"$request_uri","status":$status,"body_bytes_sent":$body_bytes_sent,"http_referer":"$http_referer","http_user_agent":"$http_user_agent","request_length":$request_length,"request_time":$request_time,"proxy_upstream_name":"$proxy_upstream_name","upstream_addr":"$upstream_addr","upstream_status":"$upstream_status","upstream_response_time":"$upstream_response_time"}`

type IngressAccessStatus struct {
	Namespace         string `json:"namespace"`
	Deployment        string `json:"deployment"`
	Image             string `json:"image"`
	ConfigMap         string `json:"configMap"`
	ConfigMapAttached bool   `json:"configMapAttached"`
	CurrentFormat     string `json:"currentFormat"`
	TargetFormat      string `json:"targetFormat"`
	Standardized      bool   `json:"standardized"`
	ManagedBy         string `json:"managedBy"`
}

func ingressConfigArg(args []string) string {
	for i, arg := range args {
		if strings.HasPrefix(arg, "--configmap=") {
			return strings.TrimPrefix(arg, "--configmap=")
		}
		if arg == "--configmap" && i+1 < len(args) {
			return args[i+1]
		}
	}
	return ""
}

func ingressAccessState(ctx context.Context, cluster *models.Cluster) (IngressAccessStatus, error) {
	client, err := clusterClient(cluster, 10*time.Second)
	if err != nil {
		return IngressAccessStatus{}, err
	}
	dep, err := client.AppsV1().Deployments(ingressNamespace).Get(ctx, ingressControllerName, metav1.GetOptions{})
	if err != nil {
		return IngressAccessStatus{}, fmt.Errorf("读取 ingress-nginx 控制器失败: %w", err)
	}
	index := -1
	for i, container := range dep.Spec.Template.Spec.Containers {
		if strings.Contains(container.Image, "ingress-nginx/controller:") {
			index = i
			break
		}
	}
	if index < 0 {
		return IngressAccessStatus{}, fmt.Errorf("未识别到社区 ingress-nginx controller 容器")
	}
	container := dep.Spec.Template.Spec.Containers[index]
	configName := ingressConfigArg(container.Args)
	if configName == "" {
		configName = ingressNamespace + "/" + ingressControllerName
	}
	parts := strings.Split(configName, "/")
	if len(parts) != 2 || parts[0] != ingressNamespace || parts[1] == "" {
		return IngressAccessStatus{}, fmt.Errorf("控制器使用其他命名空间的 ConfigMap: %s", configName)
	}
	cm, err := client.CoreV1().ConfigMaps(parts[0]).Get(ctx, parts[1], metav1.GetOptions{})
	if err != nil {
		return IngressAccessStatus{}, fmt.Errorf("读取 ingress-nginx ConfigMap 失败: %w", err)
	}
	format := cm.Data["log-format-upstream"]
	return IngressAccessStatus{
		Namespace: ingressNamespace, Deployment: dep.Name, Image: container.Image,
		ConfigMap: configName, ConfigMapAttached: ingressConfigArg(container.Args) != "",
		CurrentFormat: format, TargetFormat: ingressAccessFormat,
		Standardized: format == ingressAccessFormat && cm.Data["log-format-escape-json"] == "true" && ingressConfigArg(container.Args) != "",
		ManagedBy:    dep.Labels["app.kubernetes.io/managed-by"],
	}, nil
}

func InspectIngressAccess(ctx context.Context, cluster *models.Cluster) (IngressAccessStatus, error) {
	return ingressAccessState(ctx, cluster)
}

// ApplyIngressAccess changes only the two log keys, preserving unrelated ingress settings.
// Explicitly attaching the ConfigMap is necessary for controllers launched without --configmap.
func ApplyIngressAccess(ctx context.Context, cluster *models.Cluster) (IngressAccessStatus, error) {
	state, err := ingressAccessState(ctx, cluster)
	if err != nil {
		return state, err
	}
	client, err := clusterClient(cluster, 10*time.Second)
	if err != nil {
		return state, err
	}
	parts := strings.Split(state.ConfigMap, "/")
	cm, err := client.CoreV1().ConfigMaps(parts[0]).Get(ctx, parts[1], metav1.GetOptions{})
	if err != nil {
		return state, err
	}
	if !state.ConfigMapAttached {
		for key := range cm.Data {
			if key != "log-format-upstream" && key != "log-format-escape-json" {
				return state, fmt.Errorf("控制器尚未关联 ConfigMap，且其中已有 %s 等设置；为避免意外启用原有配置，已跳过自动配置", key)
			}
		}
	}
	previousFormat := strings.Replace(ingressAccessFormat, `"request":"$request",`, "", 1)
	if current := cm.Data["log-format-upstream"]; current != "" && current != ingressAccessFormat && current != previousFormat {
		return state, fmt.Errorf("已有自定义 access log 格式；为避免覆盖，已跳过自动配置")
	}
	if state.Standardized {
		if err := ensureIngressRolloutStrategy(ctx, cluster); err != nil {
			return state, err
		}
		return state, nil
	}
	if cm.Data == nil {
		cm.Data = make(map[string]string)
	}
	cm.Data["log-format-upstream"] = ingressAccessFormat
	cm.Data["log-format-escape-json"] = "true"
	if _, err = client.CoreV1().ConfigMaps(parts[0]).Update(ctx, cm, metav1.UpdateOptions{}); err != nil {
		return state, fmt.Errorf("更新 ingress-nginx ConfigMap 失败: %w", err)
	}
	if !state.ConfigMapAttached {
		dep, err := client.AppsV1().Deployments(ingressNamespace).Get(ctx, ingressControllerName, metav1.GetOptions{})
		if err != nil {
			return state, err
		}
		for i := range dep.Spec.Template.Spec.Containers {
			container := &dep.Spec.Template.Spec.Containers[i]
			if strings.Contains(container.Image, "ingress-nginx/controller:") {
				container.Args = append(container.Args, "--configmap="+state.ConfigMap)
				break
			}
		}
		setIngressRolloutStrategy(dep)
		if _, err = client.AppsV1().Deployments(ingressNamespace).Update(ctx, dep, metav1.UpdateOptions{}); err != nil {
			return state, fmt.Errorf("ConfigMap 已更新，但控制器尚未关联配置；更新 Deployment 失败: %w", err)
		}
	}
	return ingressAccessState(ctx, cluster)
}

// Host-network replicas occupying every ingress node cannot use a surge pod:
// the new pod would need the same 80/443 ports as an existing replica.
func setIngressRolloutStrategy(dep *appsv1.Deployment) bool {
	if !dep.Spec.Template.Spec.HostNetwork || dep.Spec.Replicas == nil || *dep.Spec.Replicas < 2 {
		return false
	}
	zero, one := intstr.FromInt32(0), intstr.FromInt32(1)
	strategy := &dep.Spec.Strategy
	if strategy.Type == appsv1.RecreateDeploymentStrategyType {
		return false
	}
	if strategy.RollingUpdate != nil && strategy.RollingUpdate.MaxSurge != nil && *strategy.RollingUpdate.MaxSurge == zero && strategy.RollingUpdate.MaxUnavailable != nil && *strategy.RollingUpdate.MaxUnavailable == one {
		return false
	}
	strategy.Type = appsv1.RollingUpdateDeploymentStrategyType
	strategy.RollingUpdate = &appsv1.RollingUpdateDeployment{MaxSurge: &zero, MaxUnavailable: &one}
	return true
}

func ensureIngressRolloutStrategy(ctx context.Context, cluster *models.Cluster) error {
	client, err := clusterClient(cluster, 10*time.Second)
	if err != nil {
		return err
	}
	dep, err := client.AppsV1().Deployments(ingressNamespace).Get(ctx, ingressControllerName, metav1.GetOptions{})
	if err != nil {
		return err
	}
	if setIngressRolloutStrategy(dep) {
		_, err = client.AppsV1().Deployments(ingressNamespace).Update(ctx, dep, metav1.UpdateOptions{})
	}
	return err
}