proxy-pool/internal/controller/bootstrap/bootstrap.go

package bootstrap

import (
	"context"
	"errors"
	"fmt"
	"reflect"
	"strings"
	"time"

	"github.com/prometheus/client_golang/prometheus"

	"proxy-pool/internal/config"
	"proxy-pool/internal/controller/admin"
	"proxy-pool/internal/controller/distribution"
	"proxy-pool/internal/controller/extraction"
	"proxy-pool/internal/controller/operations"
	controllerRuntime "proxy-pool/internal/controller/runtime"
	"proxy-pool/internal/domain/activitypool"
	extractionDomain "proxy-pool/internal/domain/extraction"
	"proxy-pool/internal/platform/admission"
	"proxy-pool/internal/platform/httpserver"
	platformMetrics "proxy-pool/internal/platform/metrics"
)

var (
	ErrInvalidOptions = errors.New("invalid controller bootstrap options")
	ErrStartup        = errors.New("controller startup failed")
)

type Options struct {
	ConfigPath string
	Resolver   config.Resolver
	Now        func() time.Time
	HTTP       httpserver.Options
}

type activityStore interface {
	extractionDomain.Store
	activitypool.StateInventoryReader
}

type ports struct {
	state            admin.StateRepository
	activity         activityStore
	readiness        distribution.ReadinessChecker
	metricsReadiness platformMetrics.ReadinessChecker
	close            func() error
}

type infrastructure interface {
	Open(context.Context, *config.Config) (ports, error)
}

type controllerRunner interface {
	Run(context.Context) error
}

type runtimeFactory interface {
	New(*config.Config, controllerRuntime.Dependencies, controllerRuntime.Options) (controllerRunner, error)
}

func Run(ctx context.Context, options Options) error {
	return run(ctx, options, &productionInfrastructure{}, productionRuntimeFactory{})
}

func run(ctx context.Context, options Options, infrastructure infrastructure, factory runtimeFactory) (resultErr error) {
	if ctx == nil || strings.TrimSpace(options.ConfigPath) != options.ConfigPath || options.ConfigPath == "" ||
		nilInterface(options.Resolver) || nilInterface(infrastructure) || nilInterface(factory) {
		return ErrInvalidOptions
	}
	if err := ctx.Err(); err != nil {
		return err
	}
	if options.Now == nil {
		options.Now = time.Now
	}

	loader, err := admin.NewFileConfigurationLoader(options.ConfigPath, options.Resolver)
	if err != nil {
		return errors.Join(ErrInvalidOptions, err)
	}
	loaded, err := loader.LoadConfiguration(ctx)
	if err != nil {
		return fmt.Errorf("%w: load configuration: %w", ErrStartup, err)
	}
	configurationStore, err := config.NewStore(loaded.Value)
	if err != nil {
		return fmt.Errorf("%w: initialize configuration store: %w", ErrStartup, err)
	}

	opened, err := infrastructure.Open(ctx, loaded.Value)
	if err != nil {
		return fmt.Errorf("%w: open infrastructure: %w", ErrStartup, err)
	}
	if opened.close == nil {
		return errors.Join(ErrStartup, ErrInvalidOptions)
	}
	defer func() {
		resultErr = errors.Join(resultErr, opened.close())
	}()

	dependencies := controllerRuntime.Dependencies{}
	if loaded.Value.Distribution.Enabled {
		if nilInterface(opened.activity) || nilInterface(opened.readiness) {
			return errors.Join(ErrStartup, ErrInvalidOptions)
		}
		service, serviceErr := extraction.NewService(opened.activity, extractionPolicy(loaded.Value), admission.AllowAll{}, options.Now)
		if serviceErr != nil {
			return fmt.Errorf("%w: build extraction service: %w", ErrStartup, serviceErr)
		}
		dependencies.Extractor = service
		dependencies.Readiness = opened.readiness
	}
	if loaded.Value.Admin.Enabled {
		if nilInterface(opened.state) || nilInterface(opened.activity) {
			return errors.Join(ErrStartup, ErrInvalidOptions)
		}
		statusReader, statusErr := operations.NewReader(configurationStore, opened.activity, options.Now)
		if statusErr != nil {
			return fmt.Errorf("%w: build operational status reader: %w", ErrStartup, statusErr)
		}
		service, serviceErr := admin.NewApplicationService(admin.ApplicationDependencies{
			State: opened.state, Operations: statusReader, Configuration: loader, Publisher: configurationStore,
		}, admin.ApplicationOptions{Now: options.Now})
		if serviceErr != nil {
			return fmt.Errorf("%w: build admin service: %w", ErrStartup, serviceErr)
		}
		if _, applyErr := service.ApplyConfiguration(ctx, admin.ReloadCommand{
			RequestID: "controller-startup", ActorID: "proxy-controller",
		}, loaded); applyErr != nil {
			return fmt.Errorf("%w: commit startup configuration: %w", ErrStartup, applyErr)
		}
		dependencies.AdminService = service
	}
	if loaded.Value.Metrics.Enabled {
		if nilInterface(opened.metricsReadiness) {
			return errors.Join(ErrStartup, ErrInvalidOptions)
		}
		handler, handlerErr := platformMetrics.NewHandler(platformMetrics.Dependencies{
			Gatherer: prometheus.DefaultGatherer, Readiness: opened.metricsReadiness,
		})
		if handlerErr != nil {
			return fmt.Errorf("%w: build metrics handler: %w", ErrStartup, handlerErr)
		}
		dependencies.MetricsHandler = handler
	}

	runner, err := factory.New(configurationStore.Current(), dependencies, controllerRuntime.Options{HTTP: options.HTTP})
	if err != nil {
		return fmt.Errorf("%w: build HTTP runtime: %w", ErrStartup, err)
	}
	if nilInterface(runner) {
		return errors.Join(ErrStartup, ErrInvalidOptions)
	}
	return runner.Run(ctx)
}

func extractionPolicy(configuration *config.Config) extraction.Policy {
	configured := configuration.Distribution.Extraction
	return extraction.Policy{
		MaxCountPerRequest: configured.MaxCountPerRequest,
		DefaultFulfillment: extractionDomain.Fulfillment(configured.Fulfillment),
		MinRemainingTTL:    configured.MinRemainingTTL.Value(),
		MaxHealthCheckAge:  configured.MaxHealthCheckAge.Value(),
		ReserveForGateway:  configured.ReserveForGateway,
		IdempotencyTTL:     configured.IdempotencyTTL.Value(),
	}
}

func nilInterface(value any) bool {
	if value == nil {
		return true
	}
	reflected := reflect.ValueOf(value)
	switch reflected.Kind() {
	case reflect.Chan, reflect.Func, reflect.Interface, reflect.Map, reflect.Pointer, reflect.Slice:
		return reflected.IsNil()
	default:
		return false
	}
}

type productionRuntimeFactory struct{}

func (productionRuntimeFactory) New(
	configuration *config.Config,
	dependencies controllerRuntime.Dependencies,
	options controllerRuntime.Options,
) (controllerRunner, error) {
	return controllerRuntime.New(configuration, dependencies, options)
}