package remoteapi

import (
	"context"
	"database/sql"
	"fmt"
	"net"

	remotesapi "github.com/dolthub/dolt/go/gen/proto/dolt/services/remotesapi/v1alpha1"
	"github.com/dolthub/dolt/go/libraries/doltcore/remotesrv"
	"github.com/dolthub/dolt/go/libraries/utils/filesys"
	"github.com/sirupsen/logrus"
	"github.com/vaughan0/go-ini"

	"go.bigb.es/sourcehut-dolt/db"
	"go.bigb.es/sourcehut-dolt/storage"
)

// serviceName is the SourceHut service identifier for dolt.sr.ht. It selects
// the config section and OAuth grant namespace used across the auth stack.
const serviceName = "dolt.sr.ht"

// Config configures the remotesapi server assembly. It is the single struct the
// main wiring populates for both New (the chunk-store server) and NewCredServer
// (the credentials server); each uses the subset it needs.
type Config struct {
	// Conf is the loaded instance config (the shared config.ini as ini.File),
	// threaded into request contexts so the auth resolvers can read
	// [webhooks]private-key, network-key, meta origin, etc.
	Conf ini.File
	// DB is the shared Postgres pool.
	DB *sql.DB
	// ReposRoot is the absolute directory under which bare NBS stores live
	// ("<ReposRoot>/~<owner>/<name>"). The remotesrv filesys is rooted here.
	ReposRoot string
	// ListenAddr is the host:port for the remotesapi (gRPC + HTTP chunk data
	// plane multiplexed on one h2c port).
	ListenAddr string
	// CredsListenAddr is the host:port for the separate CredentialsService
	// (WhoAmI) gRPC server.
	CredsListenAddr string
	// HttpHost is the authority the server stamps into sealed chunk-download
	// URLs (e.g. "dolt.srht.bigb.es"; may carry a port for local testing, e.g.
	// "127.0.0.1:5306"). It also seeds the expected JWT audience: dolt's client
	// derives the audience with net.SplitHostPort(endpoint), i.e. the bare host
	// with any port stripped, so the audience the server must expect is
	// normalizeAud(HttpHost). Leave empty to echo the request :authority into
	// chunk URLs (auth then cannot be host-checked; used only by tests without a
	// stable host).
	HttpHost string
	// Logger is the base logger; may be nil (a default is used).
	Logger *logrus.Entry
}

// Server is the assembled remotesapi server: the remotesrv chunk-store server
// plus the storage cache it serves from. The cache is exposed so the web delete
// flow can evict a store when its repository is removed.
type Server struct {
	srv    *remotesrv.Server
	cache  *storage.Cache
	logger *logrus.Entry
	addr   string
}

// New assembles the remotesapi chunk-store server: a db-backed repo lookup, the
// storage cache, our auth/authz interceptors, and the importable remotesrv
// server bound to a single h2c port. It does not start listening; call Serve.
func New(cfg Config) (*Server, error) {
	if cfg.DB == nil {
		return nil, fmt.Errorf("remoteapi: New requires a non-nil DB")
	}
	if cfg.ReposRoot == "" {
		return nil, fmt.Errorf("remoteapi: New requires a ReposRoot")
	}
	logger := cfg.Logger
	if logger == nil {
		logger = logrus.NewEntry(logrus.StandardLogger())
	}

	// Repo lookup: resolve owner/name to the absolute on-disk store dir via the
	// repository row. v1 has no push-to-create, so a missing row is an error the
	// cache propagates (mapped to gRPC NotFound at the interceptor layer, which
	// runs first anyway).
	lookup := func(ctx context.Context, owner, name string) (string, error) {
		repo, err := db.NewStore(cfg.DB).GetRepoByOwnerAndName(ctx, owner, name)
		if err != nil {
			return "", err
		}
		return repo.Path, nil
	}
	cache := storage.NewCache(lookup)

	keys := newKeyStore(cfg.DB)
	icept := newInterceptor(cfg.Conf, serviceName, normalizeAud(cfg.HttpHost), cfg.DB, keys, logger)

	// Load-bearing (see storage/init.go): the FS MUST be rooted at ReposRoot via
	// LocalFilesysWithWorkingDir so sealed chunk-download URLs carry clean
	// relative prefixes; a bare LocalFS breaks every clone/push at chunk
	// transfer.
	fs, err := filesys.LocalFilesysWithWorkingDir(cfg.ReposRoot)
	if err != nil {
		return nil, fmt.Errorf("remoteapi: root filesys at %q: %w", cfg.ReposRoot, err)
	}

	srv, err := remotesrv.NewServer(remotesrv.ServerArgs{
		Logger:             logger,
		HttpHost:           cfg.HttpHost,
		HttpListenAddr:     cfg.ListenAddr,
		GrpcListenAddr:     cfg.ListenAddr, // == HttpListenAddr ⇒ single h2c port
		FS:                 fs,
		DBCache:            cache,
		ReadOnly:           false,
		Options:            icept.Options(),
		ConcurrencyControl: remotesapi.PushConcurrencyControl_PUSH_CONCURRENCY_CONTROL_IGNORE_WORKING_SET,
	})
	if err != nil {
		if cerr := cache.Close(); cerr != nil {
			logger.Warnf("remoteapi: closing cache after NewServer failure: %v", cerr)
		}
		return nil, fmt.Errorf("remoteapi: remotesrv.NewServer: %w", err)
	}

	return &Server{srv: srv, cache: cache, logger: logger, addr: cfg.ListenAddr}, nil
}

// Cache returns the storage cache backing this server so the web delete flow
// can evict a store on repository removal.
func (s *Server) Cache() *storage.Cache { return s.cache }

// Serve binds the listeners and serves until GracefulStop. It blocks. It
// returns an error only if binding the listeners fails; the underlying
// remotesrv.Serve blocks until shutdown and does not return an error.
func (s *Server) Serve() error {
	listeners, err := s.srv.Listeners()
	if err != nil {
		return fmt.Errorf("remoteapi: bind %q: %w", s.addr, err)
	}
	s.srv.Serve(listeners)
	return nil
}

// GracefulStop stops the server and closes every memoized chunk store.
func (s *Server) GracefulStop() {
	s.srv.GracefulStop()
	if err := s.cache.Close(); err != nil {
		s.logger.Warnf("remoteapi: closing cache on shutdown: %v", err)
	}
}

// normalizeAud reduces a configured HttpHost to the bare host the dolt client
// puts in a JWT audience. Verified against dolt's grpc_dial_provider:
// getHostFromEndpoint(endpoint) calls net.SplitHostPort and returns the host
// with any port stripped, so the audience the server receives is always the
// bare host. Normalizing here lets operators write either "dolt.srht.bigb.es"
// or "dolt.srht.bigb.es:443" (or a "127.0.0.1:PORT" test host) and get the same
// expected audience. An empty host yields an empty audience (no keypair auth).
func normalizeAud(host string) string {
	if host == "" {
		return ""
	}
	if h, _, err := net.SplitHostPort(host); err == nil {
		return h
	}
	return host
}