package featuremgmt

import (
	"fmt"
	"net/http"
	"net/url"
	"time"

	clientauthmiddleware "github.com/grafana/grafana/pkg/clientauth/middleware"
	"github.com/grafana/grafana/pkg/setting"
	"github.com/open-feature/go-sdk/openfeature/memprovider"

	sdkhttpclient "github.com/grafana/grafana-plugin-sdk-go/backend/httpclient"
	"github.com/open-feature/go-sdk/openfeature"
)

const (
	featuresProviderAudience = "features.grafana.app"
)

// OpenFeatureConfig holds configuration for initializing OpenFeature
type OpenFeatureConfig struct {
	// ProviderType is either "static", "features-service", or "ofrep"
	ProviderType string
	// URL is the remote provider's URL (required for features-service + OFREP providers)
	URL *url.URL
	// HTTPClient is a pre-configured HTTP client (optional, used by features-service + OFREP providers)
	HTTPClient *http.Client
	// StaticFlags are the feature flags to use with static provider
	StaticFlags map[string]memprovider.InMemoryFlag
	// TargetingKey is used for evaluation context
	TargetingKey string
	// ContextAttrs are additional attributes for evaluation context
	ContextAttrs map[string]any
}

// InitOpenFeature initializes OpenFeature with the provided configuration
func InitOpenFeature(config OpenFeatureConfig) error {
	// For remote providers, ensure we have a URL
	if (config.ProviderType == setting.FeaturesServiceProviderType || config.ProviderType == setting.OFREPProviderType) && (config.URL == nil || config.URL.String() == "") {
		return fmt.Errorf("URL is required for remote providers")
	}

	p, err := createProvider(config.ProviderType, config.URL, config.StaticFlags, config.HTTPClient)
	if err != nil {
		return err
	}

	if err = openfeature.SetProviderAndWait(p); err != nil {
		return fmt.Errorf("failed to set global feature provider: %s, %w", config.ProviderType, err)
	}

	contextAttrs := make(map[string]any)
	for k, v := range config.ContextAttrs {
		contextAttrs[k] = v
	}
	openfeature.SetEvaluationContext(openfeature.NewEvaluationContext(config.TargetingKey, contextAttrs))

	return nil
}

// InitOpenFeatureWithCfg initializes OpenFeature from setting.Cfg
func InitOpenFeatureWithCfg(cfg *setting.Cfg) error {
	confFlags, err := setting.ReadFeatureTogglesFromInitFile(cfg.Raw.Section("feature_toggles"))
	if err != nil {
		return fmt.Errorf("failed to read feature flags from config: %w", err)
	}

	var httpcli *http.Client
	if cfg.OpenFeature.ProviderType == setting.FeaturesServiceProviderType || cfg.OpenFeature.ProviderType == setting.OFREPProviderType {
		var m *clientauthmiddleware.TokenExchangeMiddleware

		if cfg.OpenFeature.ProviderType == setting.FeaturesServiceProviderType {
			m, err = clientauthmiddleware.NewTokenExchangeMiddleware(cfg)
			if err != nil {
				return fmt.Errorf("failed to create token exchange middleware: %w", err)
			}
		}

		httpcli, err = createHTTPClient(m)
		if err != nil {
			return err
		}
	}

	contextAttrs := make(map[string]any)
	for k, v := range cfg.OpenFeature.ContextAttrs {
		contextAttrs[k] = v
	}

	return InitOpenFeature(OpenFeatureConfig{
		ProviderType: cfg.OpenFeature.ProviderType,
		URL:          cfg.OpenFeature.URL,
		HTTPClient:   httpcli,
		StaticFlags:  confFlags,
		TargetingKey: cfg.OpenFeature.TargetingKey,
		ContextAttrs: contextAttrs,
	})
}

func createProvider(
	providerType string,
	u *url.URL,
	staticFlags map[string]memprovider.InMemoryFlag,
	httpClient *http.Client,
) (openfeature.FeatureProvider, error) {
	if providerType == setting.FeaturesServiceProviderType || providerType == setting.OFREPProviderType {
		if u == nil || u.String() == "" {
			return nil, fmt.Errorf("feature provider url is required for FeaturesServiceProviderType + OFREPProviderType")
		}

		if providerType == setting.FeaturesServiceProviderType {
			return newFeaturesServiceProvider(u.String(), httpClient)
		}

		if providerType == setting.OFREPProviderType {
			return newOFREPProvider(u.String(), httpClient)
		}
	}

	return newStaticProvider(staticFlags, standardFeatureFlags)
}

func createHTTPClient(m *clientauthmiddleware.TokenExchangeMiddleware) (*http.Client, error) {
	options := sdkhttpclient.Options{
		TLS: &sdkhttpclient.TLSOptions{InsecureSkipVerify: true},
		Timeouts: &sdkhttpclient.TimeoutOptions{
			Timeout: 10 * time.Second,
		},
	}
	if m != nil {
		options.Middlewares = append(options.Middlewares, m.New([]string{featuresProviderAudience}))
	}

	httpcli, err := sdkhttpclient.NewProvider().New(options)
	if err != nil {
		return nil, fmt.Errorf("failed to create http client for openfeature: %w", err)
	}

	return httpcli, nil
}