// Copyright 2015 The go-ethereum Authors
// This file is part of the go-ethereum library.
//
// The go-ethereum library is free software: you can redistribute it and/or modify
// it under the terms of the GNU Lesser General Public License as published by
// the Free Software Foundation, either version 3 of the License, or
// (at your option) any later version.
//
// The go-ethereum library is distributed in the hope that it will be useful,
// but WITHOUT ANY WARRANTY; without even the implied warranty of
// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
// GNU Lesser General Public License for more details.
//
// You should have received a copy of the GNU Lesser General Public License
// along with the go-ethereum library. If not, see <http://www.gnu.org/licenses/>.

package node

import (
	"errors"
	"path/filepath"
	"reflect"
	"strings"
	"sync"

	"github.com/ava-labs/coreth/accounts"
	"github.com/ava-labs/coreth/core/rawdb"
	"github.com/ava-labs/coreth/internal/debug"
	"github.com/ava-labs/coreth/rpc"
	"github.com/ava-labs/go-ethereum/ethdb"
	"github.com/ava-labs/go-ethereum/event"
	"github.com/ava-labs/go-ethereum/log"
	"github.com/ava-labs/go-ethereum/p2p"
	"github.com/prometheus/tsdb/fileutil"
)

// Node is a container on which services can be registered.
type Node struct {
	eventmux *event.TypeMux // Event multiplexer used between the services of a stack
	config   *Config
	accman   *accounts.Manager

	ephemeralKeystore string            // if non-empty, the key directory that will be removed by Stop
	instanceDirLock   fileutil.Releaser // prevents concurrent use of instance directory

	serverConfig p2p.Config
	server       *p2p.Server // Currently running P2P networking layer

	serviceFuncs []ServiceConstructor     // Service constructors (in dependency order)
	services     map[reflect.Type]Service // Currently running services

	rpcAPIs       []rpc.API   // List of APIs currently provided by the node
	inprocHandler *rpc.Server // In-process RPC request handler to process the API requests

	stop chan struct{} // Channel to wait for termination notifications
	lock sync.RWMutex

	log log.Logger
}

// New creates a new P2P node, ready for protocol registration.
func New(conf *Config) (*Node, error) {
	// Copy config and resolve the datadir so future changes to the current
	// working directory don't affect the node.
	confCopy := *conf
	conf = &confCopy
	if conf.DataDir != "" {
		absdatadir, err := filepath.Abs(conf.DataDir)
		if err != nil {
			return nil, err
		}
		conf.DataDir = absdatadir
	}
	// Ensure that the instance name doesn't cause weird conflicts with
	// other files in the data directory.
	if strings.ContainsAny(conf.Name, `/\`) {
		return nil, errors.New(`Config.Name must not contain '/' or '\'`)
	}
	if conf.Name == datadirDefaultKeyStore {
		return nil, errors.New(`Config.Name cannot be "` + datadirDefaultKeyStore + `"`)
	}
	if strings.HasSuffix(conf.Name, ".ipc") {
		return nil, errors.New(`Config.Name cannot end in ".ipc"`)
	}
	// Ensure that the AccountManager method works before the node has started.
	// We rely on this in cmd/geth.
	am, ephemeralKeystore, err := makeAccountManager(conf)
	if err != nil {
		return nil, err
	}
	if conf.Logger == nil {
		conf.Logger = log.New()
	}
	// Note: any interaction with Config that would create/touch files
	// in the data directory or instance directory is delayed until Start.
	return &Node{
		accman:            am,
		ephemeralKeystore: ephemeralKeystore,
		config:            conf,
		serviceFuncs:      []ServiceConstructor{},
		eventmux:          new(event.TypeMux),
		log:               conf.Logger,
	}, nil
}

// Config returns the configuration of node.
func (n *Node) Config() *Config {
	return n.config
}

// Server retrieves the currently running P2P network layer. This method is meant
// only to inspect fields of the currently running server, life cycle management
// should be left to this Node entity.
func (n *Node) Server() *p2p.Server {
	n.lock.RLock()
	defer n.lock.RUnlock()

	return n.server
}

// Service retrieves a currently running service registered of a specific type.
func (n *Node) Service(service interface{}) error {
	n.lock.RLock()
	defer n.lock.RUnlock()

	// Short circuit if the node's not running
	if n.server == nil {
		return ErrNodeStopped
	}
	// Otherwise try to find the service to return
	element := reflect.ValueOf(service).Elem()
	if running, ok := n.services[element.Type()]; ok {
		element.Set(reflect.ValueOf(running))
		return nil
	}
	return ErrServiceUnknown
}

// DataDir retrieves the current datadir used by the protocol stack.
// Deprecated: No files should be stored in this directory, use InstanceDir instead.
func (n *Node) DataDir() string {
	return n.config.DataDir
}

// InstanceDir retrieves the instance directory used by the protocol stack.
func (n *Node) InstanceDir() string {
	return n.config.instanceDir()
}

// AccountManager retrieves the account manager used by the protocol stack.
func (n *Node) AccountManager() *accounts.Manager {
	return n.accman
}

// EventMux retrieves the event multiplexer used by all the network services in
// the current protocol stack.
func (n *Node) EventMux() *event.TypeMux {
	return n.eventmux
}

// OpenDatabase opens an existing database with the given name (or creates one if no
// previous can be found) from within the node's instance directory. If the node is
// ephemeral, a memory database is returned.
func (n *Node) OpenDatabase(name string, cache, handles int, namespace string) (ethdb.Database, error) {
	if n.config.DataDir == "" {
		return rawdb.NewMemoryDatabase(), nil
	}
	return rawdb.NewLevelDBDatabase(n.config.ResolvePath(name), cache, handles, namespace)
}

// OpenDatabaseWithFreezer opens an existing database with the given name (or
// creates one if no previous can be found) from within the node's data directory,
// also attaching a chain freezer to it that moves ancient chain data from the
// database to immutable append-only files. If the node is an ephemeral one, a
// memory database is returned.
func (n *Node) OpenDatabaseWithFreezer(name string, cache, handles int, freezer, namespace string) (ethdb.Database, error) {
	if n.config.DataDir == "" {
		return rawdb.NewMemoryDatabase(), nil
	}
	root := n.config.ResolvePath(name)

	switch {
	case freezer == "":
		freezer = filepath.Join(root, "ancient")
	case !filepath.IsAbs(freezer):
		freezer = n.config.ResolvePath(freezer)
	}
	return rawdb.NewLevelDBDatabaseWithFreezer(root, cache, handles, freezer, namespace)
}

// ResolvePath returns the absolute path of a resource in the instance directory.
func (n *Node) ResolvePath(x string) string {
	return n.config.ResolvePath(x)
}

// apis returns the collection of RPC descriptors this node offers.
func (n *Node) apis() []rpc.API {
	return []rpc.API{
		{
			Namespace: "admin",
			Version:   "1.0",
			Service:   NewPrivateAdminAPI(n),
		}, {
			Namespace: "admin",
			Version:   "1.0",
			Service:   NewPublicAdminAPI(n),
			Public:    true,
		}, {
			Namespace: "debug",
			Version:   "1.0",
			Service:   debug.Handler,
		}, {
			Namespace: "web3",
			Version:   "1.0",
			Service:   NewPublicWeb3API(n),
			Public:    true,
		},
	}
}