package config

import (
	"errors"
	"fmt"
	"os"
	"strings"

	monov1alpha1 "undecided.project/monok8s/pkg/apis/monok8s/v1alpha1"
	"gopkg.in/yaml.v3"
)

const EnvVar = "MONOKSCONFIG"

type Loader struct{}

func (Loader) ResolvePath(flagValue string) (string, error) {
	if strings.TrimSpace(flagValue) != "" {
		return flagValue, nil
	}
	if env := strings.TrimSpace(os.Getenv(EnvVar)); env != "" {
		return env, nil
	}
	return "", fmt.Errorf("config path not provided; pass -c or set %s", EnvVar)
}

func (Loader) Load(path string) (*monov1alpha1.MonoKSConfig, error) {
	data, err := os.ReadFile(path)
	if err != nil {
		return nil, err
	}
	var cfg monov1alpha1.MonoKSConfig
	if err := yaml.Unmarshal(data, &cfg); err != nil {
		return nil, err
	}
	if cfg.Kind == "" {
		cfg.Kind = "MonoKSConfig"
	}
	if cfg.APIVersion == "" {
		cfg.APIVersion = monov1alpha1.Group + "/" + monov1alpha1.Version
	}
	ApplyDefaults(&cfg)
	if err := Validate(&cfg); err != nil {
		return nil, err
	}
	return &cfg, nil
}

func ApplyDefaults(cfg *monov1alpha1.MonoKSConfig) {
	if cfg.Spec.PodSubnet == "" {
		cfg.Spec.PodSubnet = "10.244.0.0/16"
	}
	if cfg.Spec.ServiceSubnet == "" {
		cfg.Spec.ServiceSubnet = "10.96.0.0/12"
	}
	if cfg.Spec.ClusterName == "" {
		cfg.Spec.ClusterName = "monok8s"
	}
	if cfg.Spec.ClusterDomain == "" {
		cfg.Spec.ClusterDomain = "cluster.local"
	}
	if cfg.Spec.ContainerRuntimeEndpoint == "" {
		cfg.Spec.ContainerRuntimeEndpoint = "unix:///var/run/crio/crio.sock"
	}
	if cfg.Spec.BootstrapMode == "" {
		cfg.Spec.BootstrapMode = "init"
	}
	if cfg.Spec.JoinKind == "" {
		cfg.Spec.JoinKind = "worker"
	}
	if cfg.Spec.CNIPlugin == "" {
		cfg.Spec.CNIPlugin = "none"
	}
	if len(cfg.Spec.KubeProxyNodePortAddresses) == 0 {
		cfg.Spec.KubeProxyNodePortAddresses = []string{"primary"}
	}
}

func Validate(cfg *monov1alpha1.MonoKSConfig) error {
	var problems []string
	if cfg.Kind != "MonoKSConfig" {
		problems = append(problems, "kind must be MonoKSConfig")
	}
	if cfg.APIVersion != monov1alpha1.Group+"/"+monov1alpha1.Version {
		problems = append(problems, "apiVersion must be "+monov1alpha1.Group+"/"+monov1alpha1.Version)
	}
	if strings.TrimSpace(cfg.Spec.KubernetesVersion) == "" {
		problems = append(problems, "spec.kubernetesVersion is required")
	}
	if strings.TrimSpace(cfg.Spec.NodeName) == "" {
		problems = append(problems, "spec.nodeName is required")
	}
	if strings.TrimSpace(cfg.Spec.APIServerAdvertiseAddress) == "" {
		problems = append(problems, "spec.apiServerAdvertiseAddress is required")
	}
	if strings.TrimSpace(cfg.Spec.Network.Hostname) == "" {
		problems = append(problems, "spec.network.hostname is required")
	}
	if strings.TrimSpace(cfg.Spec.Network.ManagementIface) == "" {
		problems = append(problems, "spec.network.managementIface is required")
	}
	if !strings.Contains(cfg.Spec.Network.ManagementCIDR, "/") {
		problems = append(problems, "spec.network.managementCIDR must include a CIDR prefix")
	}
	if cfg.Spec.BootstrapMode != "init" && cfg.Spec.BootstrapMode != "join" {
		problems = append(problems, "spec.bootstrapMode must be init or join")
	}
	if cfg.Spec.JoinKind != "worker" && cfg.Spec.JoinKind != "control-plane" {
		problems = append(problems, "spec.joinKind must be worker or control-plane")
	}
	for _, ns := range cfg.Spec.Network.DNSNameservers {
		if ns == "10.96.0.10" {
			problems = append(problems, "spec.network.dnsNameservers must not include cluster DNS service IP 10.96.0.10")
		}
	}
	if cfg.Spec.BootstrapMode == "join" {
		if cfg.Spec.APIServerEndpoint == "" {
			problems = append(problems, "spec.apiServerEndpoint is required for join mode")
		}
		if cfg.Spec.BootstrapToken == "" {
			problems = append(problems, "spec.bootstrapToken is required for join mode")
		}
		if cfg.Spec.DiscoveryTokenCACertHash == "" {
			problems = append(problems, "spec.discoveryTokenCACertHash is required for join mode")
		}
		if cfg.Spec.JoinKind == "control-plane" && cfg.Spec.ControlPlaneCertKey == "" {
			problems = append(problems, "spec.controlPlaneCertKey is required for control-plane join")
		}
	}
	if len(problems) > 0 {
		return errors.New(strings.Join(problems, "; "))
	}
	return nil
}