// Package grpcserver implements the gRPC server for Metacrypt.
package grpcserver

import (
	"crypto/tls"
	"fmt"
	"log/slog"
	"net"
	"sync"

	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials"

	pb "git.wntrmute.dev/kyle/metacrypt/gen/metacrypt/v2"
	internacme "git.wntrmute.dev/kyle/metacrypt/internal/acme"
	"git.wntrmute.dev/kyle/metacrypt/internal/auth"
	"git.wntrmute.dev/kyle/metacrypt/internal/config"
	"git.wntrmute.dev/kyle/metacrypt/internal/engine"
	"git.wntrmute.dev/kyle/metacrypt/internal/policy"
	"git.wntrmute.dev/kyle/metacrypt/internal/seal"
)

// GRPCServer wraps the gRPC server and all service implementations.
type GRPCServer struct {
	cfg          *config.Config
	sealMgr      *seal.Manager
	auth         *auth.Authenticator
	policy       *policy.Engine
	engines      *engine.Registry
	logger       *slog.Logger
	srv          *grpc.Server
	acmeHandlers map[string]*internacme.Handler
	mu           sync.Mutex
}

// New creates a new GRPCServer.
func New(cfg *config.Config, sealMgr *seal.Manager, authenticator *auth.Authenticator,
	policyEngine *policy.Engine, engineRegistry *engine.Registry, logger *slog.Logger) *GRPCServer {
	return &GRPCServer{
		cfg:          cfg,
		sealMgr:      sealMgr,
		auth:         authenticator,
		policy:       policyEngine,
		engines:      engineRegistry,
		logger:       logger,
		acmeHandlers: make(map[string]*internacme.Handler),
	}
}

// Start starts the gRPC server on cfg.Server.GRPCAddr.
func (s *GRPCServer) Start() error {
	if s.cfg.Server.GRPCAddr == "" {
		s.logger.Info("grpc_addr not configured, gRPC server disabled")
		return nil
	}

	tlsCert, err := tls.LoadX509KeyPair(s.cfg.Server.TLSCert, s.cfg.Server.TLSKey)
	if err != nil {
		return fmt.Errorf("grpc: load TLS cert: %w", err)
	}
	tlsCfg := &tls.Config{
		Certificates: []tls.Certificate{tlsCert},
		MinVersion:   tls.VersionTLS13,
	}
	creds := credentials.NewTLS(tlsCfg)

	interceptor := chainInterceptors(
		sealInterceptor(s.sealMgr, s.logger, sealRequiredMethods()),
		authInterceptor(s.auth, s.logger, authRequiredMethods()),
		adminInterceptor(s.logger, adminRequiredMethods()),
	)

	s.srv = grpc.NewServer(
		grpc.Creds(creds),
		grpc.UnaryInterceptor(interceptor),
	)

	pb.RegisterSystemServiceServer(s.srv, &systemServer{s: s})
	pb.RegisterAuthServiceServer(s.srv, &authServer{s: s})
	pb.RegisterEngineServiceServer(s.srv, &engineServer{s: s})
	pb.RegisterPKIServiceServer(s.srv, &pkiServer{s: s})
	pb.RegisterCAServiceServer(s.srv, &caServer{s: s})
	pb.RegisterPolicyServiceServer(s.srv, &policyServer{s: s})
	pb.RegisterBarrierServiceServer(s.srv, &barrierServer{s: s})
	pb.RegisterACMEServiceServer(s.srv, &acmeServer{s: s})

	lis, err := net.Listen("tcp", s.cfg.Server.GRPCAddr)
	if err != nil {
		return fmt.Errorf("grpc: listen %s: %w", s.cfg.Server.GRPCAddr, err)
	}

	s.logger.Info("starting gRPC server", "addr", s.cfg.Server.GRPCAddr)
	if err := s.srv.Serve(lis); err != nil {
		return fmt.Errorf("grpc: serve: %w", err)
	}
	return nil
}

// Shutdown gracefully stops the gRPC server.
func (s *GRPCServer) Shutdown() {
	if s.srv != nil {
		s.srv.GracefulStop()
	}
}

// sealRequiredMethods returns the set of RPC full names that require the vault
// to be unsealed.
func sealRequiredMethods() map[string]bool {
	return map[string]bool{
		"/metacrypt.v2.AuthService/Login":          true,
		"/metacrypt.v2.AuthService/Logout":         true,
		"/metacrypt.v2.AuthService/TokenInfo":      true,
		"/metacrypt.v2.EngineService/Mount":        true,
		"/metacrypt.v2.EngineService/Unmount":      true,
		"/metacrypt.v2.EngineService/ListMounts":   true,
		"/metacrypt.v2.PKIService/GetRootCert":     true,
		"/metacrypt.v2.PKIService/GetChain":        true,
		"/metacrypt.v2.PKIService/GetIssuerCert":   true,
		"/metacrypt.v2.CAService/ImportRoot":       true,
		"/metacrypt.v2.CAService/GetRoot":          true,
		"/metacrypt.v2.CAService/CreateIssuer":     true,
		"/metacrypt.v2.CAService/DeleteIssuer":     true,
		"/metacrypt.v2.CAService/ListIssuers":      true,
		"/metacrypt.v2.CAService/GetIssuer":        true,
		"/metacrypt.v2.CAService/GetChain":         true,
		"/metacrypt.v2.CAService/IssueCert":        true,
		"/metacrypt.v2.CAService/GetCert":          true,
		"/metacrypt.v2.CAService/ListCerts":        true,
		"/metacrypt.v2.CAService/RenewCert":        true,
		"/metacrypt.v2.CAService/SignCSR":          true,
		"/metacrypt.v2.CAService/RevokeCert":       true,
		"/metacrypt.v2.CAService/DeleteCert":       true,
		"/metacrypt.v2.PolicyService/CreatePolicy": true,
		"/metacrypt.v2.PolicyService/ListPolicies": true,
		"/metacrypt.v2.PolicyService/GetPolicy":    true,
		"/metacrypt.v2.PolicyService/DeletePolicy": true,
		"/metacrypt.v2.ACMEService/CreateEAB":      true,
		"/metacrypt.v2.ACMEService/SetConfig":      true,
		"/metacrypt.v2.ACMEService/ListAccounts":   true,
		"/metacrypt.v2.ACMEService/ListOrders":      true,
		"/metacrypt.v2.BarrierService/ListKeys":     true,
		"/metacrypt.v2.BarrierService/RotateMEK":    true,
		"/metacrypt.v2.BarrierService/RotateKey":    true,
		"/metacrypt.v2.BarrierService/Migrate":      true,
	}
}

// authRequiredMethods returns the set of RPC full names that require a valid token.
func authRequiredMethods() map[string]bool {
	return map[string]bool{
		"/metacrypt.v2.AuthService/Logout":         true,
		"/metacrypt.v2.AuthService/TokenInfo":      true,
		"/metacrypt.v2.EngineService/Mount":        true,
		"/metacrypt.v2.EngineService/Unmount":      true,
		"/metacrypt.v2.EngineService/ListMounts":   true,
		"/metacrypt.v2.CAService/ImportRoot":       true,
		"/metacrypt.v2.CAService/CreateIssuer":     true,
		"/metacrypt.v2.CAService/DeleteIssuer":     true,
		"/metacrypt.v2.CAService/ListIssuers":      true,
		"/metacrypt.v2.CAService/IssueCert":        true,
		"/metacrypt.v2.CAService/GetCert":          true,
		"/metacrypt.v2.CAService/ListCerts":        true,
		"/metacrypt.v2.CAService/RenewCert":        true,
		"/metacrypt.v2.CAService/SignCSR":          true,
		"/metacrypt.v2.CAService/RevokeCert":       true,
		"/metacrypt.v2.CAService/DeleteCert":       true,
		"/metacrypt.v2.PolicyService/CreatePolicy": true,
		"/metacrypt.v2.PolicyService/ListPolicies": true,
		"/metacrypt.v2.PolicyService/GetPolicy":    true,
		"/metacrypt.v2.PolicyService/DeletePolicy": true,
		"/metacrypt.v2.ACMEService/CreateEAB":      true,
		"/metacrypt.v2.ACMEService/SetConfig":      true,
		"/metacrypt.v2.ACMEService/ListAccounts":   true,
		"/metacrypt.v2.ACMEService/ListOrders":      true,
		"/metacrypt.v2.BarrierService/ListKeys":     true,
		"/metacrypt.v2.BarrierService/RotateMEK":    true,
		"/metacrypt.v2.BarrierService/RotateKey":    true,
		"/metacrypt.v2.BarrierService/Migrate":      true,
	}
}

// adminRequiredMethods returns the set of RPC full names that require admin.
func adminRequiredMethods() map[string]bool {
	return map[string]bool{
		"/metacrypt.v2.SystemService/Seal":         true,
		"/metacrypt.v2.EngineService/Mount":        true,
		"/metacrypt.v2.EngineService/Unmount":      true,
		"/metacrypt.v2.CAService/ImportRoot":       true,
		"/metacrypt.v2.CAService/CreateIssuer":     true,
		"/metacrypt.v2.CAService/DeleteIssuer":     true,
		"/metacrypt.v2.CAService/RevokeCert":       true,
		"/metacrypt.v2.CAService/DeleteCert":       true,
		"/metacrypt.v2.PolicyService/CreatePolicy": true,
		"/metacrypt.v2.PolicyService/ListPolicies": true,
		"/metacrypt.v2.PolicyService/GetPolicy":    true,
		"/metacrypt.v2.PolicyService/DeletePolicy":  true,
		"/metacrypt.v2.ACMEService/SetConfig":      true,
		"/metacrypt.v2.ACMEService/ListAccounts":   true,
		"/metacrypt.v2.ACMEService/ListOrders":      true,
		"/metacrypt.v2.BarrierService/ListKeys":     true,
		"/metacrypt.v2.BarrierService/RotateMEK":    true,
		"/metacrypt.v2.BarrierService/RotateKey":    true,
		"/metacrypt.v2.BarrierService/Migrate":      true,
	}
}