package tree

import (
	"context"
	"fmt"
	"sync"

	grpcService "git.frostfs.info/TrueCloudLab/frostfs-sdk-go/pool/tree/service"
	"google.golang.org/grpc"
)

type treeClient struct {
	mu      sync.RWMutex
	address string
	opts    []grpc.DialOption
	conn    *grpc.ClientConn
	service grpcService.TreeServiceClient
	healthy bool
}

// newTreeClient creates new tree client with auto dial.
func newTreeClient(addr string, opts ...grpc.DialOption) *treeClient {
	return &treeClient{
		address: addr,
		opts:    opts,
	}
}

func (c *treeClient) dial(ctx context.Context) error {
	c.mu.Lock()
	defer c.mu.Unlock()

	if c.conn != nil {
		return fmt.Errorf("couldn't dial '%s': connection already established", c.address)
	}

	var err error
	c.conn, err = grpc.DialContext(ctx, c.address, c.opts...)
	if err != nil {
		return fmt.Errorf("grpc dial node tree service: %w", err)
	}

	c.service = grpcService.NewTreeServiceClient(c.conn)
	if _, err = c.service.Healthcheck(ctx, &grpcService.HealthcheckRequest{}); err != nil {
		return fmt.Errorf("healthcheck tree service: %w", err)
	}

	c.healthy = true

	return nil
}

func (c *treeClient) redialIfNecessary(ctx context.Context) (healthHasChanged bool, err error) {
	c.mu.Lock()
	defer c.mu.Unlock()

	if c.conn == nil {
		c.conn, err = grpc.DialContext(ctx, c.address, c.opts...)
		if err != nil {
			return false, fmt.Errorf("grpc dial node tree service: %w", err)
		}

		c.service = grpcService.NewTreeServiceClient(c.conn)
	}

	wasHealthy := c.healthy
	if _, err = c.service.Healthcheck(ctx, &grpcService.HealthcheckRequest{}); err != nil {
		c.healthy = false
		return wasHealthy, fmt.Errorf("healthcheck tree service: %w", err)
	}

	c.healthy = true

	return !wasHealthy, nil
}

func (c *treeClient) serviceClient() (grpcService.TreeServiceClient, error) {
	c.mu.RLock()
	defer c.mu.RUnlock()

	if c.conn == nil || !c.healthy {
		return nil, fmt.Errorf("unhealthy endpoint: '%s'", c.address)
	}

	return c.service, nil
}

func (c *treeClient) endpoint() string {
	return c.address
}

func (c *treeClient) isHealthy() bool {
	c.mu.RLock()
	defer c.mu.RUnlock()
	return c.healthy
}

func (c *treeClient) setHealthy(val bool) {
	c.mu.Lock()
	defer c.mu.Unlock()
	c.healthy = val
}

func (c *treeClient) close() error {
	c.mu.Lock()
	defer c.mu.Unlock()

	if c.conn == nil {
		return nil
	}

	return c.conn.Close()
}