package featureflag

import (
	"errors"
	"os"
	"time"

	"github.com/launchdarkly/go-sdk-common/v3/ldcontext"
	ld "github.com/launchdarkly/go-server-sdk/v6"
)

var (
	client *ld.LDClient

	recreateClient bool // this is set to true whenever the SetConfig function is called.
	config         ld.Config
)

var ErrNoAPIKey = errors.New("LD_KEY not set")

func Client() (*ld.LDClient, error) {
	if client != nil && !recreateClient {
		return client, nil
	}
	recreateClient = false

	// if no LD_KEY is given, then a custom data source is required,
	// The custom data source is set when testing using the testutil package.
	key, hasKey := os.LookupEnv("LD_KEY")
	if !hasKey && config.DataSource == nil {
		return nil, ErrNoAPIKey
	}
	var err error
	client, err = ld.MakeCustomClient(key, config, 10*time.Second)
	return client, err
}

func SetConfig(c ld.Config) {
	recreateClient = true
	config = c
}

// FeatureEnabledForContext wraps BoolVariation to get the value of a boolean
// feature flag for a particular LD Context.
func FeatureEnabledForContext(ctxer Contextualizer, feature string, defaultVal bool) (bool, error) {
	client, err := Client()
	if err != nil {
		return defaultVal, err
	}
	ldCtx := ldcontext.NewWithKind(ctxer.Kind(), ctxer.Key())
	return client.BoolVariation(feature, ldCtx, defaultVal)
}

// FeatureEnabledForBanner is a helper wrapping [FeatureEnabledForContext] that automatically creates a
// [BannerContext].
func FeatureEnabledForBanner(feature, banner string, defaultVal bool) (bool, error) {
	return FeatureEnabledForContext(NewBannerContext(banner), feature, defaultVal)
}

// FeatureEnabledForLDContext wraps BoolVariation to get the value of a boolean
// feature flag for a particular LD Context.
func FeatureEnabledForLDContext(feature string, ldcontext ldcontext.Context, defaultVal bool) (bool, error) {
	client, err := Client()
	if err != nil {
		return defaultVal, err
	}
	return client.BoolVariation(feature, ldcontext, defaultVal)
}

// FeatureEnabled is a helper wrapping FeatureEnabledForContext that automatically creates an
// EnvironmentContext, which is a rule not targeted to a specific Context.
func FeatureEnabled(feature string, defaultVal bool) (bool, error) {
	return FeatureEnabledForContext(NewEnvironmentContext(), feature, defaultVal)
}