feat: initial commit

reach/client/client.go

@@ -0,0 +1,96 @@
+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
+
+	proto protocol.Identifier
+	ops   protocol.Operations
+
+	getProtocolOnce    sync.Once
+	getProtocolOnceErr error
+}
+
+func (c *Client) Protocol(ctx context.Context) (protocol.Identifier, protocol.Operations, error) {
+	id, ops, err := c.getProtocol(ctx)
+	if err != nil {
+		return "", nil, errors.WithStack(err)
+	}
+
+	return id, ops, nil
+}
+
+func (c *Client) getProtocol(ctx context.Context) (protocol.Identifier, protocol.Operations, error) {
+	c.getProtocolOnce.Do(func() {
+		availables, err := c.opts.Protocols.Availables(ctx, c.addr)
+		if err != nil {
+			c.getProtocolOnceErr = errors.WithStack(err)
+			return
+		}
+
+		var preferred protocol.Protocol
+		var fallback protocol.Protocol
+
+		for _, proto := range availables {
+			if proto.Identifier() == c.opts.FallbackProtocol {
+				fallback = proto
+			}
+
+			if proto.Identifier() == c.opts.PreferredProtocol {
+				preferred = proto
+				break
+			}
+		}
+
+		if preferred != nil {
+			c.proto = preferred.Identifier()
+			c.ops = preferred.Operations(c.addr)
+			return
+		}
+
+		if fallback != nil {
+			c.proto = fallback.Identifier()
+			c.ops = fallback.Operations(c.addr)
+			return
+		}
+
+		for _, proto := range availables {
+			if proto.Identifier() != c.opts.FallbackProtocol {
+				continue
+			}
+
+			fallback = proto
+			break
+		}
+
+		if fallback == nil {
+			c.getProtocolOnceErr = errors.Errorf("neither preferred protocol '%v' or fallback '%v' are available", c.opts.PreferredProtocol, c.opts.FallbackProtocol)
+			return
+		}
+
+		c.proto = fallback.Identifier()
+		c.ops = fallback.Operations(c.addr)
+	})
+	if c.getProtocolOnceErr != nil {
+		return "", nil, errors.WithStack(c.getProtocolOnceErr)
+	}
+
+	return c.proto, c.ops, nil
+}
+
+func NewClient(addr string, funcs ...OptionFunc) *Client {
+	opts := NewOptions(funcs...)
+	client := &Client{
+		addr: addr,
+		opts: opts,
+	}
+	return client
+}