go-emlid/reach/client/client.go

package client

import (
	"context"
	"sync"

	"forge.cadoles.com/cadoles/go-emlid/reach/client/protocol"
	"github.com/pkg/errors"
)

type Client struct {
	addr string
	opts *Options

	ops           protocol.Operations
	getOpsOnce    sync.Once
	getOpsOnceErr error
}

// Close implements protocol.Operations.
func (c *Client) Close() error {
	panic("unimplemented")
}

// Connect implements protocol.Operations.
func (c *Client) Connect(ctx context.Context) error {
	ops, err := c.getOperations(ctx)
	if err != nil {
		return errors.WithStack(err)
	}

	if err := ops.Connect(ctx); err != nil {
		return errors.WithStack(err)
	}

	return nil
}

func (c *Client) getOperations(ctx context.Context) (protocol.Operations, error) {
	c.getOpsOnce.Do(func() {
		availables, err := c.opts.Protocols.Availables(ctx, c.addr)
		if err != nil {
			c.getOpsOnceErr = errors.WithStack(err)
			return
		}

		var preferred protocol.Operations
		var fallback protocol.Operations

		for _, proto := range availables {
			if proto.Identifier() == c.opts.FallbackProtocol {
				fallback = proto.Operations(c.addr)
			}

			if proto.Identifier() == c.opts.PreferredProtocol {
				preferred = proto.Operations(c.addr)
				break
			}
		}

		if preferred != nil {
			c.ops = preferred
			return
		}

		if fallback != nil {
			c.ops = fallback
			return
		}

		for _, proto := range availables {
			if proto.Identifier() != c.opts.FallbackProtocol {
				continue
			}

			fallback = proto.Operations(c.addr)
			break
		}

		if fallback == nil {
			c.getOpsOnceErr = errors.Errorf("neither preferred protocol '%v' or fallback '%v' are available", c.opts.PreferredProtocol, c.opts.FallbackProtocol)
			return
		}

		c.ops = fallback
	})
	if c.getOpsOnceErr != nil {
		return nil, errors.WithStack(c.getOpsOnceErr)
	}

	return c.ops, nil
}

func NewClient(addr string, funcs ...OptionFunc) *Client {
	opts := NewOptions(funcs...)
	client := &Client{
		addr: addr,
		opts: opts,
	}
	return client
}

var _ protocol.Operations = &Client{}