package shreder

import (
	"bytes"
	"context"
	"errors"
	"fmt"
	"runtime"
	"time"

	"github.com/gagliardetto/solana-go/rpc"
	"github.com/panjf2000/ants/v2"
	"google.golang.org/grpc"
	"google.golang.org/grpc/credentials/insecure"
)

type Client struct {
	enableBlockStats bool
	enableParseStats bool

	conn         *grpc.ClientConn
	client       ShrederServiceClient
	tableLoader  *AddressTables
	subscription map[string]*SubscribeRequestFilterTransactions

	pool *ants.Pool

	lastSlot     uint64
	lastSlotTime time.Time
}

type ClientOpts struct {
	blockStats      bool
	showTableLoaded bool
	logParseStats   bool
}

type ClientOption func(*ClientOpts)

func ShowTableLoaded(enable bool) ClientOption {
	return func(opts *ClientOpts) {
		opts.showTableLoaded = enable
	}
}

func BlocksStats(enable bool) ClientOption {
	return func(opts *ClientOpts) {
		opts.blockStats = enable
	}
}

// LogParsedStats enables logging of parsed transaction statistics.
// Deprecated: do not use.
func LogParsedStats(enable bool) ClientOption {
	return func(opts *ClientOpts) {
		opts.logParseStats = enable
	}
}

func NewShrederClient(
	url string,
	rpcClient *rpc.Client,
	subscription map[string]*SubscribeRequestFilterTransactions,
	options ...ClientOption,
) (*Client, func(), error) {
	if rpcClient == nil {
		return nil, func() {}, fmt.Errorf("rpc client is nil")
	}

	conn, err := grpc.NewClient(url, grpc.WithTransportCredentials(insecure.NewCredentials()))
	if err != nil {
		return nil, func() {}, err
	}

	poolSize := runtime.NumCPU()*2 + 2
	logger.Info("creating shreder client", "url", url, "pool_size", poolSize)
	pool, err := ants.NewPool(poolSize, ants.WithNonblocking(false))
	if err != nil {
		return nil, func() {}, err
	}
	o := &ClientOpts{
		blockStats:      false,
		showTableLoaded: true,
		logParseStats:   false,
	}
	for _, option := range options {
		option(o)
	}
	s := &Client{
		conn:         conn,
		client:       NewShrederServiceClient(conn),
		subscription: subscription,
		tableLoader:  NewAddressTables(rpcClient, o.showTableLoaded),
		pool:         pool,

		enableBlockStats: o.blockStats,
		enableParseStats: o.logParseStats,
	}

	return s, func() {
		s.Wait()
	}, nil
}

func (c *Client) Wait() {
	logger.Debug("waiting for shreder client to stop")

	if c.pool != nil {
		c.pool.Release()
	}

	err := c.conn.Close()
	if err != nil {
		logger.Error("failed to close connection: ", "err", err)
	}

	logger.Debug("shreder client stopped")
}

func (c *Client) ReadEntriesSync(ctx context.Context, txCh chan<- TxSignal) error {
	stream, err := c.client.SubscribeEntries(ctx, &SubscribeEntriesRequest{})
	if err != nil {
		return err
	}

	logger.Debug("reading entries from shreder client")
	for {
		response, err := stream.Recv()
		if err != nil {
			return err
		}
		slot := response.Slot
		if c.enableBlockStats {
			now := time.Now()
			if c.lastSlotTime.IsZero() || slot > c.lastSlot {
				if !c.lastSlotTime.IsZero() {
					logger.Info("block processed", "running", c.pool.Running(), "slot", slot, "prev_slot", c.lastSlot, "delta_ms", now.Sub(c.lastSlotTime).Milliseconds())
				}
				c.lastSlot = slot
				c.lastSlotTime = now
			}
		}

		err = c.pool.Submit(func() {
			ParseTransactionForEntries(ctx, slot, bytes.NewReader(response.Entries), c.tableLoader, txCh)
		})
		if err != nil && errors.Is(err, ants.ErrPoolOverload) {
			logger.Warn("task pool is full")
		}
	}
}

func (c *Client) ReadSync(ctx context.Context, txCh chan<- TxSignal) error {
	stream, err := c.client.SubscribeTransactions(ctx)
	if err != nil {
		return err
	}

	logger.Debug("subscribing to transactions")

	err = stream.Send(&SubscribeTransactionsRequest{
		Transactions: c.subscription,
	})
	if err != nil {
		return err
	}

	// reboot the pool
	c.pool.Reboot()

	for {
		var response *SubscribeTransactionsResponse
		response, err = stream.Recv()
		if err != nil {
			break
		}

		if c.enableBlockStats {
			slot := response.Transaction.Slot
			now := time.Now()
			if c.lastSlotTime.IsZero() || slot > c.lastSlot {
				if !c.lastSlotTime.IsZero() {
					logger.Info("block processed", "running", c.pool.Running(), "slot", slot, "prev_slot", c.lastSlot, "delta_ms", now.Sub(c.lastSlotTime).Milliseconds())
				}
				c.lastSlot = slot
				c.lastSlotTime = now
			}
		}

		txData := response.Transaction

		err := c.pool.Submit(func() {
			ParseTransactionForSubscribe(ctx, txData, c.tableLoader, txCh, nil)
		})
		if err != nil && errors.Is(err, ants.ErrPoolOverload) {
			logger.Warn("task pool is full")
		}
	}

	// sync waiting for all tasks to complete
	c.pool.Release()

	return err
}