package stickers

import (
	"context"
	"errors"
	"io/ioutil"
	"math/big"
	"net/http"
	"time"

	"github.com/ipfs/go-cid"
	"github.com/multiformats/go-multibase"
	"github.com/wealdtech/go-multicodec"
	"github.com/zenthangplus/goccm"
	"olympos.io/encoding/edn"

	"github.com/ethereum/go-ethereum/accounts/abi/bind"
	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/common/hexutil"
	"github.com/ethereum/go-ethereum/log"
	"github.com/status-im/status-go/account"
	"github.com/status-im/status-go/contracts"
	"github.com/status-im/status-go/contracts/stickers"
	"github.com/status-im/status-go/eth-node/types"
	"github.com/status-im/status-go/multiaccounts/accounts"
	"github.com/status-im/status-go/params"
	"github.com/status-im/status-go/rpc"
	"github.com/status-im/status-go/services/rpcfilters"
	"github.com/status-im/status-go/services/wallet/bigint"
)

const ipfsGateway = ".ipfs.infura-ipfs.io/"
const maxConcurrentRequests = 3

// ConnectionType constants
type stickerStatus int

const (
	statusAvailable stickerStatus = iota
	statusInstalled
	statusPending
	statusPurchased
)

type API struct {
	contractMaker   *contracts.ContractMaker
	accountsManager *account.GethManager
	accountsDB      *accounts.Database
	rpcFiltersSrvc  *rpcfilters.Service
	config          *params.NodeConfig
	ctx             context.Context
	client          *http.Client
}

type Sticker struct {
	PackID *bigint.BigInt `json:"packID,omitempty"`
	URL    string         `json:"url,omitempty"`
	Hash   string         `json:"hash,omitempty"`
}

type StickerPack struct {
	ID        *bigint.BigInt `json:"id"`
	Name      string         `json:"name"`
	Author    string         `json:"author"`
	Owner     common.Address `json:"owner,omitempty"`
	Price     *bigint.BigInt `json:"price"`
	Preview   string         `json:"preview"`
	Thumbnail string         `json:"thumbnail"`
	Stickers  []Sticker      `json:"stickers"`

	Status stickerStatus `json:"status,omitempty"`
}

type StickerPackCollection map[uint]StickerPack

type ednSticker struct {
	Hash string
}

type ednStickerPack struct {
	Name      string
	Author    string
	Thumbnail string
	Preview   string
	Stickers  []ednSticker
}
type ednStickerPackInfo struct {
	Meta ednStickerPack
}

func NewAPI(ctx context.Context, acc *accounts.Database, rpcClient *rpc.Client, accountsManager *account.GethManager, rpcFiltersSrvc *rpcfilters.Service, config *params.NodeConfig) *API {
	return &API{
		contractMaker: &contracts.ContractMaker{
			RPCClient: rpcClient,
		},
		accountsManager: accountsManager,
		accountsDB:      acc,
		rpcFiltersSrvc:  rpcFiltersSrvc,
		config:          config,
		ctx:             ctx,
		client: &http.Client{
			Timeout: time.Second * 5,
		},
	}
}

func (api *API) Market(chainID uint64) ([]StickerPack, error) {
	// TODO: eventually this should be changed to include pagination
	accs, err := api.accountsDB.GetAccounts()
	if err != nil {
		return nil, err
	}

	allStickerPacks, err := api.getContractPacks(chainID)
	if err != nil {
		return nil, err
	}

	purchasedPacks := make(map[uint]struct{})

	purchasedPackChan := make(chan *big.Int)
	errChan := make(chan error)
	doneChan := make(chan struct{}, 1)
	go api.getAccountsPurchasedPack(chainID, accs, purchasedPackChan, errChan, doneChan)

	for {
		select {
		case err := <-errChan:
			if err != nil {
				return nil, err
			}
		case packID := <-purchasedPackChan:
			if packID != nil {
				purchasedPacks[uint(packID.Uint64())] = struct{}{}
			}

		case <-doneChan:
			var result []StickerPack
			for _, pack := range allStickerPacks {
				packID := uint(pack.ID.Uint64())
				_, isPurchased := purchasedPacks[packID]
				if isPurchased {
					pack.Status = statusPurchased
				} else {
					pack.Status = statusAvailable
				}
				result = append(result, pack)
			}

			return result, nil
		}
	}
}

func (api *API) execTokenPackID(chainID uint64, tokenIDs []*big.Int, resultChan chan<- *big.Int, errChan chan<- error, doneChan chan<- struct{}) {
	defer close(doneChan)
	defer close(errChan)
	defer close(resultChan)

	stickerPack, err := api.contractMaker.NewStickerPack(chainID)
	if err != nil {
		errChan <- err
		return
	}

	if len(tokenIDs) == 0 {
		return
	}

	callOpts := &bind.CallOpts{Context: api.ctx, Pending: false}

	c := goccm.New(maxConcurrentRequests)
	for _, tokenID := range tokenIDs {
		c.Wait()
		go func(tokenID *big.Int) {
			defer c.Done()
			packID, err := stickerPack.TokenPackId(callOpts, tokenID)
			if err != nil {
				errChan <- err
				return
			}
			resultChan <- packID
		}(tokenID)
	}
	c.WaitAllDone()
}

func (api *API) getTokenPackIDs(chainID uint64, tokenIDs []*big.Int) ([]*big.Int, error) {
	tokenPackIDChan := make(chan *big.Int)
	errChan := make(chan error)
	doneChan := make(chan struct{}, 1)

	go api.execTokenPackID(chainID, tokenIDs, tokenPackIDChan, errChan, doneChan)

	var tokenPackIDs []*big.Int
	for {
		select {
		case <-doneChan:
			return tokenPackIDs, nil
		case err := <-errChan:
			if err != nil {
				return nil, err
			}
		case t := <-tokenPackIDChan:
			if t != nil {
				tokenPackIDs = append(tokenPackIDs, t)
			}
		}
	}
}

func (api *API) getPurchasedPackIDs(chainID uint64, account types.Address) ([]*big.Int, error) {
	// TODO: this should be replaced in the future by something like TheGraph to reduce the number of requests to infura

	stickerPack, err := api.contractMaker.NewStickerPack(chainID)
	if err != nil {
		return nil, err
	}

	callOpts := &bind.CallOpts{Context: api.ctx, Pending: false}

	balance, err := stickerPack.BalanceOf(callOpts, common.Address(account))
	if err != nil {
		return nil, err
	}

	tokenIDs, err := api.getTokenOwnerOfIndex(chainID, account, balance)
	if err != nil {
		return nil, err
	}

	return api.getTokenPackIDs(chainID, tokenIDs)
}

func hashToURL(hash []byte) (string, error) {
	// contract response includes a contenthash, which needs to be decoded to reveal
	// an IPFS identifier. Once decoded, download the content from IPFS. This content
	// is in EDN format, ie https://ipfs.infura.io/ipfs/QmWVVLwVKCwkVNjYJrRzQWREVvEk917PhbHYAUhA1gECTM
	// and it also needs to be decoded in to a nim type

	data, codec, err := multicodec.RemoveCodec(hash)
	if err != nil {
		return "", err
	}

	codecName, err := multicodec.Name(codec)
	if err != nil {
		return "", err
	}

	if codecName != "ipfs-ns" {
		return "", errors.New("codecName is not ipfs-ns")
	}

	thisCID, err := cid.Parse(data)
	if err != nil {
		return "", err
	}

	str, err := thisCID.StringOfBase(multibase.Base32)
	if err != nil {
		return "", err
	}

	return "https://" + str + ipfsGateway, nil
}

func (api *API) fetchStickerPacks(chainID uint64, resultChan chan<- *StickerPack, errChan chan<- error, doneChan chan<- struct{}) {
	defer close(doneChan)
	defer close(errChan)
	defer close(resultChan)

	installedPacks, err := api.Installed()
	if err != nil {
		errChan <- err
		return
	}

	pendingPacks, err := api.pendingStickerPacks()
	if err != nil {
		errChan <- err
		return
	}

	stickerType, err := api.contractMaker.NewStickerType(chainID)
	if err != nil {
		errChan <- err
		return
	}

	callOpts := &bind.CallOpts{Context: api.ctx, Pending: false}

	numPacks, err := stickerType.PackCount(callOpts)
	if err != nil {
		errChan <- err
		return
	}

	if numPacks.Uint64() == 0 {
		return
	}

	c := goccm.New(maxConcurrentRequests)
	for i := uint64(0); i < numPacks.Uint64(); i++ {
		c.Wait()
		go func(i uint64) {
			defer c.Done()

			packID := new(big.Int).SetUint64(i)

			_, exists := installedPacks[uint(i)]
			if exists {
				return // We already have the sticker pack data, no need to query it
			}

			_, exists = pendingPacks[uint(i)]
			if exists {
				return // We already have the sticker pack data, no need to query it
			}

			stickerPack, err := api.fetchPackData(stickerType, packID, true)
			if err != nil {
				log.Warn("Could not retrieve stickerpack data", "packID", packID, "error", err)
				return
			}

			resultChan <- stickerPack
		}(i)
	}

	c.WaitAllDone()
}

func (api *API) fetchPackData(stickerType *stickers.StickerType, packID *big.Int, translateHashes bool) (*StickerPack, error) {
	callOpts := &bind.CallOpts{Context: api.ctx, Pending: false}

	packData, err := stickerType.GetPackData(callOpts, packID)
	if err != nil {
		return nil, err
	}

	packDetailsURL, err := hashToURL(packData.Contenthash)
	if err != nil {
		return nil, err
	}

	stickerPack := &StickerPack{
		ID:    &bigint.BigInt{Int: packID},
		Owner: packData.Owner,
		Price: &bigint.BigInt{Int: packData.Price},
	}

	err = api.downloadIPFSData(stickerPack, packDetailsURL, translateHashes)
	if err != nil {
		return nil, err
	}

	return stickerPack, nil
}

func (api *API) downloadIPFSData(stickerPack *StickerPack, packDetailsURL string, translateHashes bool) error {
	// This can be improved by adding a cache using packDetailsURL as key

	req, err := http.NewRequest(http.MethodGet, packDetailsURL, nil)
	if err != nil {
		return err
	}

	resp, err := api.client.Do(req)
	if err != nil {
		return err
	}

	defer func() {
		if err := resp.Body.Close(); err != nil {
			log.Error("failed to close the stickerpack request body", "err", err)
		}
	}()

	body, err := ioutil.ReadAll(resp.Body)
	if err != nil {
		return err
	}

	return populateStickerPackAttributes(stickerPack, body, translateHashes)
}

func populateStickerPackAttributes(stickerPack *StickerPack, ednSource []byte, translateHashes bool) error {
	var stickerpackIPFSInfo ednStickerPackInfo
	err := edn.Unmarshal(ednSource, &stickerpackIPFSInfo)
	if err != nil {
		return err
	}

	stickerPack.Author = stickerpackIPFSInfo.Meta.Author
	stickerPack.Name = stickerpackIPFSInfo.Meta.Name

	if translateHashes {
		stickerPack.Preview, err = decodeStringHash(stickerpackIPFSInfo.Meta.Preview)
		if err != nil {
			return err
		}

		stickerPack.Thumbnail, err = decodeStringHash(stickerpackIPFSInfo.Meta.Thumbnail)
		if err != nil {
			return err
		}
	} else {
		stickerPack.Preview = stickerpackIPFSInfo.Meta.Preview
		stickerPack.Thumbnail = stickerpackIPFSInfo.Meta.Thumbnail
	}

	for _, s := range stickerpackIPFSInfo.Meta.Stickers {
		url := ""
		if translateHashes {
			hash, err := hexutil.Decode("0x" + s.Hash)
			if err != nil {
				return err
			}

			url, err = hashToURL(hash)
			if err != nil {
				return err
			}
		}

		stickerPack.Stickers = append(stickerPack.Stickers, Sticker{
			PackID: stickerPack.ID,
			URL:    url,
			Hash:   s.Hash,
		})
	}

	return nil
}

func decodeStringHash(input string) (string, error) {
	hash, err := hexutil.Decode("0x" + input)
	if err != nil {
		return "", err
	}

	url, err := hashToURL(hash)
	if err != nil {
		return "", err
	}

	return url, nil
}

func (api *API) getContractPacks(chainID uint64) ([]StickerPack, error) {
	stickerPackChan := make(chan *StickerPack)
	errChan := make(chan error)
	doneChan := make(chan struct{}, 1)

	go api.fetchStickerPacks(chainID, stickerPackChan, errChan, doneChan)

	var packs []StickerPack

	for {
		select {
		case <-doneChan:
			return packs, nil
		case err := <-errChan:
			if err != nil {
				return nil, err
			}
		case pack := <-stickerPackChan:
			if pack != nil {
				packs = append(packs, *pack)
			}
		}
	}
}

func (api *API) getAccountsPurchasedPack(chainID uint64, accs []accounts.Account, resultChan chan<- *big.Int, errChan chan<- error, doneChan chan<- struct{}) {
	defer close(doneChan)
	defer close(errChan)
	defer close(resultChan)

	if len(accs) == 0 {
		return
	}

	c := goccm.New(maxConcurrentRequests)
	for _, account := range accs {
		c.Wait()
		go func(acc accounts.Account) {
			defer c.Done()
			packs, err := api.getPurchasedPackIDs(chainID, acc.Address)
			if err != nil {
				errChan <- err
				return
			}

			for _, p := range packs {
				resultChan <- p
			}
		}(account)
	}
	c.WaitAllDone()
}

func (api *API) execTokenOwnerOfIndex(chainID uint64, account types.Address, balance *big.Int, resultChan chan<- *big.Int, errChan chan<- error, doneChan chan<- struct{}) {
	defer close(doneChan)
	defer close(errChan)
	defer close(resultChan)

	stickerPack, err := api.contractMaker.NewStickerPack(chainID)
	if err != nil {
		errChan <- err
		return
	}

	if balance.Int64() == 0 {
		return
	}

	callOpts := &bind.CallOpts{Context: api.ctx, Pending: false}

	c := goccm.New(maxConcurrentRequests)
	for i := uint64(0); i < balance.Uint64(); i++ {
		c.Wait()
		go func(i uint64) {
			defer c.Done()
			tokenID, err := stickerPack.TokenOfOwnerByIndex(callOpts, common.Address(account), new(big.Int).SetUint64(i))
			if err != nil {
				errChan <- err
				return
			}

			resultChan <- tokenID
		}(i)
	}
	c.WaitAllDone()
}

func (api *API) getTokenOwnerOfIndex(chainID uint64, account types.Address, balance *big.Int) ([]*big.Int, error) {
	tokenIDChan := make(chan *big.Int)
	errChan := make(chan error)
	doneChan := make(chan struct{}, 1)

	go api.execTokenOwnerOfIndex(chainID, account, balance, tokenIDChan, errChan, doneChan)

	var tokenIDs []*big.Int
	for {
		select {
		case <-doneChan:
			return tokenIDs, nil
		case err := <-errChan:
			if err != nil {
				return nil, err
			}
		case tokenID := <-tokenIDChan:
			if tokenID != nil {
				tokenIDs = append(tokenIDs, tokenID)
			}
		}
	}
}