package jsonrpc

import (
	"errors"
	"fmt"
	"io/ioutil"
	"time"

	"github.com/daglabs/btcd/apiserver/config"
	"github.com/daglabs/btcd/util/daghash"

	"github.com/daglabs/btcd/rpcclient"
	"github.com/daglabs/btcd/util"
	"github.com/daglabs/btcd/wire"
)

// Client represents a connection to the JSON-RPC API of a full node
type Client struct {
	*rpcclient.Client
	onBlockAdded   chan *blockAddedMsg
	onChainChanged chan *chainChangedMsg
}

var client *Client

// GetClient returns an instance of the JSON-RPC client, in case we have an active connection
func GetClient() (*Client, error) {
	if client == nil {
		return nil, errors.New("JSON-RPC is not connected")
	}

	return client, nil
}

type blockAddedMsg struct {
	chainHeight uint64
	header      *wire.BlockHeader
}

type chainChangedMsg struct {
	removedChainBlockHashes []*daghash.Hash
	addedChainBlocks        []*rpcclient.ChainBlock
}

// Close closes the connection to the JSON-RPC API server
func Close() {
	if client == nil {
		return
	}

	client.Disconnect()
	client = nil
}

// Connect initiates a connection to the JSON-RPC API Server
func Connect(cfg *config.Config) error {
	var cert []byte
	if !cfg.DisableTLS {
		var err error
		cert, err = ioutil.ReadFile(cfg.RPCCert)
		if err != nil {
			return fmt.Errorf("Error reading certificates file: %s", err)
		}
	}

	connCfg := &rpcclient.ConnConfig{
		Host:           cfg.RPCServer,
		Endpoint:       "ws",
		User:           cfg.RPCUser,
		Pass:           cfg.RPCPassword,
		DisableTLS:     cfg.DisableTLS,
		RequestTimeout: time.Second * 5,
	}

	if !cfg.DisableTLS {
		connCfg.Certificates = cert
	}

	var err error
	client, err = newClient(connCfg)
	if err != nil {
		return fmt.Errorf("Error connecting to address %s: %s", cfg.RPCServer, err)
	}

	return nil
}

func newClient(connCfg *rpcclient.ConnConfig) (*Client, error) {
	client = &Client{
		onBlockAdded:   make(chan *blockAddedMsg),
		onChainChanged: make(chan *chainChangedMsg),
	}
	notificationHandlers := &rpcclient.NotificationHandlers{
		OnFilteredBlockAdded: func(height uint64, header *wire.BlockHeader,
			txs []*util.Tx) {
			client.onBlockAdded <- &blockAddedMsg{
				chainHeight: height,
				header:      header,
			}
		},
		OnChainChanged: func(removedChainBlockHashes []*daghash.Hash,
			addedChainBlocks []*rpcclient.ChainBlock) {
			client.onChainChanged <- &chainChangedMsg{
				removedChainBlockHashes: removedChainBlockHashes,
				addedChainBlocks:        addedChainBlocks,
			}
		},
	}
	var err error
	client.Client, err = rpcclient.New(connCfg, notificationHandlers)
	if err != nil {
		return nil, fmt.Errorf("Error connecting to address %s: %s", connCfg.Host, err)
	}

	if err = client.NotifyBlocks(); err != nil {
		return nil, fmt.Errorf("Error while registering client %s for block notifications: %s", client.Host(), err)
	}
	if err = client.NotifyChainChanges(); err != nil {
		return nil, fmt.Errorf("Error while registering client %s for chain changes notifications: %s", client.Host(), err)
	}

	return client, nil
}