package collectibles

import (
	"context"
	"encoding/json"
	"errors"
	"math/big"
	"sync/atomic"
	"time"

	"github.com/ethereum/go-ethereum/common"
	"github.com/ethereum/go-ethereum/event"
	"github.com/ethereum/go-ethereum/log"
	"github.com/status-im/status-go/services/wallet/async"
	"github.com/status-im/status-go/services/wallet/bigint"
	walletCommon "github.com/status-im/status-go/services/wallet/common"
	"github.com/status-im/status-go/services/wallet/thirdparty"
	"github.com/status-im/status-go/services/wallet/transfer"
	"github.com/status-im/status-go/services/wallet/walletevent"
)

const (
	fetchLimit                          = 50 // Limit number of collectibles we fetch per provider call
	accountOwnershipUpdateInterval      = 60 * time.Minute
	accountOwnershipUpdateDelayInterval = 30 * time.Second
)

type OwnershipState = int

type OwnedCollectibles struct {
	chainID walletCommon.ChainID
	account common.Address
	ids     []thirdparty.CollectibleUniqueID
}

type OwnedCollectiblesChangeType = int

const (
	OwnedCollectiblesChangeTypeAdded OwnedCollectiblesChangeType = iota + 1
	OwnedCollectiblesChangeTypeUpdated
	OwnedCollectiblesChangeTypeRemoved
)

type OwnedCollectiblesChange struct {
	ownedCollectibles OwnedCollectibles
	changeType        OwnedCollectiblesChangeType
}

type OwnedCollectiblesChangeCb func(OwnedCollectiblesChange)

type TransferCb func(common.Address, walletCommon.ChainID, []transfer.Transfer)

const (
	OwnershipStateIdle OwnershipState = iota + 1
	OwnershipStateDelayed
	OwnershipStateUpdating
	OwnershipStateError
)

type periodicRefreshOwnedCollectiblesCommand struct {
	chainID                   walletCommon.ChainID
	account                   common.Address
	manager                   *Manager
	ownershipDB               *OwnershipDB
	walletFeed                *event.Feed
	ownedCollectiblesChangeCb OwnedCollectiblesChangeCb

	group *async.Group
	state atomic.Value
}

func newPeriodicRefreshOwnedCollectiblesCommand(
	manager *Manager,
	ownershipDB *OwnershipDB,
	walletFeed *event.Feed,
	chainID walletCommon.ChainID,
	account common.Address,
	ownedCollectiblesChangeCb OwnedCollectiblesChangeCb) *periodicRefreshOwnedCollectiblesCommand {
	ret := &periodicRefreshOwnedCollectiblesCommand{
		manager:                   manager,
		ownershipDB:               ownershipDB,
		walletFeed:                walletFeed,
		chainID:                   chainID,
		account:                   account,
		ownedCollectiblesChangeCb: ownedCollectiblesChangeCb,
	}
	ret.state.Store(OwnershipStateIdle)
	return ret
}

func (c *periodicRefreshOwnedCollectiblesCommand) DelayedCommand() async.Command {
	return async.SingleShotCommand{
		Interval: accountOwnershipUpdateDelayInterval,
		Init: func(ctx context.Context) (err error) {
			c.state.Store(OwnershipStateDelayed)
			return nil
		},
		Runable: c.Command(),
	}.Run
}

func (c *periodicRefreshOwnedCollectiblesCommand) Command() async.Command {
	return async.InfiniteCommand{
		Interval: accountOwnershipUpdateInterval,
		Runable:  c.Run,
	}.Run
}

func (c *periodicRefreshOwnedCollectiblesCommand) Run(ctx context.Context) (err error) {
	return c.loadOwnedCollectibles(ctx)
}

func (c *periodicRefreshOwnedCollectiblesCommand) GetState() OwnershipState {
	return c.state.Load().(OwnershipState)
}

func (c *periodicRefreshOwnedCollectiblesCommand) Stop() {
	if c.group != nil {
		c.group.Stop()
		c.group.Wait()
		c.group = nil
	}
}

func (c *periodicRefreshOwnedCollectiblesCommand) loadOwnedCollectibles(ctx context.Context) error {
	c.group = async.NewGroup(ctx)

	ownedCollectiblesChangeCh := make(chan OwnedCollectiblesChange)
	command := newLoadOwnedCollectiblesCommand(c.manager, c.ownershipDB, c.walletFeed, c.chainID, c.account, ownedCollectiblesChangeCh)

	c.state.Store(OwnershipStateUpdating)
	defer func() {
		if command.err != nil {
			c.state.Store(OwnershipStateError)
		} else {
			c.state.Store(OwnershipStateIdle)
		}
	}()

	c.group.Add(command.Command())

	select {
	case ownedCollectiblesChange := <-ownedCollectiblesChangeCh:
		if c.ownedCollectiblesChangeCb != nil {
			c.ownedCollectiblesChangeCb(ownedCollectiblesChange)
		}
	case <-ctx.Done():
		return ctx.Err()
	case <-c.group.WaitAsync():
		return nil
	}

	return nil
}

// Fetches owned collectibles for a ChainID+OwnerAddress combination in chunks
// and updates the ownershipDB when all chunks are loaded
type loadOwnedCollectiblesCommand struct {
	chainID                   walletCommon.ChainID
	account                   common.Address
	manager                   *Manager
	ownershipDB               *OwnershipDB
	walletFeed                *event.Feed
	ownedCollectiblesChangeCh chan<- OwnedCollectiblesChange

	// Not to be set by the caller
	partialOwnership []thirdparty.CollectibleUniqueID
	err              error
}

func newLoadOwnedCollectiblesCommand(
	manager *Manager,
	ownershipDB *OwnershipDB,
	walletFeed *event.Feed,
	chainID walletCommon.ChainID,
	account common.Address,
	ownedCollectiblesChangeCh chan<- OwnedCollectiblesChange) *loadOwnedCollectiblesCommand {
	return &loadOwnedCollectiblesCommand{
		manager:                   manager,
		ownershipDB:               ownershipDB,
		walletFeed:                walletFeed,
		chainID:                   chainID,
		account:                   account,
		ownedCollectiblesChangeCh: ownedCollectiblesChangeCh,
	}
}

func (c *loadOwnedCollectiblesCommand) Command() async.Command {
	return c.Run
}

func (c *loadOwnedCollectiblesCommand) triggerEvent(eventType walletevent.EventType, chainID walletCommon.ChainID, account common.Address, message string) {
	c.walletFeed.Send(walletevent.Event{
		Type:    eventType,
		ChainID: uint64(chainID),
		Accounts: []common.Address{
			account,
		},
		Message: message,
	})
}

func ownedTokensToTokenBalancesPerContractAddress(ownership []thirdparty.CollectibleUniqueID) thirdparty.TokenBalancesPerContractAddress {
	ret := make(thirdparty.TokenBalancesPerContractAddress)
	for _, id := range ownership {
		balance := thirdparty.TokenBalance{
			TokenID: id.TokenID,
			Balance: &bigint.BigInt{Int: big.NewInt(1)},
		}
		ret[id.ContractID.Address] = append(ret[id.ContractID.Address], balance)
	}
	return ret
}

func (c *loadOwnedCollectiblesCommand) sendOwnedCollectiblesChanges(removed, updated, added []thirdparty.CollectibleUniqueID) {
	if len(removed) > 0 {
		c.ownedCollectiblesChangeCh <- OwnedCollectiblesChange{
			ownedCollectibles: OwnedCollectibles{
				chainID: c.chainID,
				account: c.account,
				ids:     removed,
			},
			changeType: OwnedCollectiblesChangeTypeRemoved,
		}
	}

	if len(updated) > 0 {
		c.ownedCollectiblesChangeCh <- OwnedCollectiblesChange{
			ownedCollectibles: OwnedCollectibles{
				chainID: c.chainID,
				account: c.account,
				ids:     updated,
			},
			changeType: OwnedCollectiblesChangeTypeUpdated,
		}
	}

	if len(added) > 0 {
		c.ownedCollectiblesChangeCh <- OwnedCollectiblesChange{
			ownedCollectibles: OwnedCollectibles{
				chainID: c.chainID,
				account: c.account,
				ids:     added,
			},
			changeType: OwnedCollectiblesChangeTypeAdded,
		}
	}
}

func (c *loadOwnedCollectiblesCommand) Run(parent context.Context) (err error) {
	log.Debug("start loadOwnedCollectiblesCommand", "chain", c.chainID, "account", c.account)

	pageNr := 0
	cursor := thirdparty.FetchFromStartCursor
	providerID := thirdparty.FetchFromAnyProvider
	start := time.Now()

	c.triggerEvent(EventCollectiblesOwnershipUpdateStarted, c.chainID, c.account, "")

	updateMessage := OwnershipUpdateMessage{}

	lastFetchTimestamp, err := c.ownershipDB.GetOwnershipUpdateTimestamp(c.account, c.chainID)
	if err != nil {
		c.err = err
	} else {
		initialFetch := lastFetchTimestamp == InvalidTimestamp
		// Fetch collectibles in chunks
		for {
			if walletCommon.ShouldCancel(parent) {
				c.err = errors.New("context cancelled")
				break
			}

			pageStart := time.Now()
			log.Debug("start loadOwnedCollectiblesCommand", "chain", c.chainID, "account", c.account, "page", pageNr)

			partialOwnership, err := c.manager.FetchCollectibleOwnershipByOwner(parent, c.chainID, c.account, cursor, fetchLimit, providerID)

			if err != nil {
				log.Error("failed loadOwnedCollectiblesCommand", "chain", c.chainID, "account", c.account, "page", pageNr, "error", err)
				c.err = err
				break
			}

			log.Debug("partial loadOwnedCollectiblesCommand", "chain", c.chainID, "account", c.account, "page", pageNr, "in", time.Since(pageStart), "found", len(partialOwnership.Items))

			c.partialOwnership = append(c.partialOwnership, partialOwnership.Items...)

			pageNr++
			cursor = partialOwnership.NextCursor
			providerID = partialOwnership.Provider

			finished := cursor == thirdparty.FetchFromStartCursor

			// Normally, update the DB once we've finished fetching
			// If this is the first fetch, make partial updates to the client to get a better UX
			if initialFetch || finished {
				// Token balances should come from the providers. For now we assume all balances are 1, which
				// is only valid for ERC721.
				// TODO (#13025): Fetch balances from the providers.
				balances := ownedTokensToTokenBalancesPerContractAddress(c.partialOwnership)

				updateMessage.Removed, updateMessage.Updated, updateMessage.Added, err = c.ownershipDB.Update(c.chainID, c.account, balances, start.Unix())
				if err != nil {
					log.Error("failed updating ownershipDB in loadOwnedCollectiblesCommand", "chain", c.chainID, "account", c.account, "error", err)
					c.err = err
					break
				}

				c.sendOwnedCollectiblesChanges(updateMessage.Removed, updateMessage.Updated, updateMessage.Added)
			}

			if finished || c.err != nil {
				break
			} else if initialFetch {
				encodedMessage, err := json.Marshal(updateMessage)
				if err != nil {
					c.err = err
					break
				}
				c.triggerEvent(EventCollectiblesOwnershipUpdatePartial, c.chainID, c.account, string(encodedMessage))

				updateMessage = OwnershipUpdateMessage{}
			}
		}
	}

	var encodedMessage []byte
	if c.err == nil {
		encodedMessage, c.err = json.Marshal(updateMessage)
	}

	if c.err != nil {
		c.triggerEvent(EventCollectiblesOwnershipUpdateFinishedWithError, c.chainID, c.account, c.err.Error())
	} else {
		c.triggerEvent(EventCollectiblesOwnershipUpdateFinished, c.chainID, c.account, string(encodedMessage))
	}

	log.Debug("end loadOwnedCollectiblesCommand", "chain", c.chainID, "account", c.account, "in", time.Since(start))
	return nil
}