multi-protocol client

Fixes #4

1 files changed, 87 insertions, 0 deletions

diff --git a/client.go b/client.go
new file mode 100644
index 0000000..3631bc5
--- /dev/null
+++ b/client.go
@@ -0,0 +1,87 @@
+package sliderule
+
+import (
+	"crypto/tls"
+	"errors"
+	"fmt"
+	neturl "net/url"
+
+	"tildegit.org/tjp/sliderule/finger"
+	"tildegit.org/tjp/sliderule/gemini"
+	"tildegit.org/tjp/sliderule/gopher"
+	"tildegit.org/tjp/sliderule/internal/types"
+	"tildegit.org/tjp/sliderule/spartan"
+)
+
+type protocolClient interface {
+	RoundTrip(*Request) (*Response, error)
+	IsRedirect(*Response) bool
+}
+
+// Client is a multi-protocol client which handles all protocols known to sliderule.
+type Client struct {
+	MaxRedirects int
+
+	protos map[string]protocolClient
+}
+
+const DefaultMaxRedirects int = 2
+
+var ExceededMaxRedirects = errors.New("Client: exceeded MaxRedirects")
+
+// NewClient builds a Client object.
+//
+// tlsConf may be nil, in which case gemini requests connections will not be made
+// with any client certificate.
+func NewClient(tlsConf *tls.Config) Client {
+	return Client{
+		protos: map[string]protocolClient{
+			"finger":  finger.Client{},
+			"gopher":  gopher.Client{},
+			"gemini":  gemini.NewClient(tlsConf),
+			"spartan": spartan.NewClient(),
+		},
+		MaxRedirects: DefaultMaxRedirects,
+	}
+}
+
+// RoundTrip sends a single request and returns the repsonse.
+//
+// If the response is a redirect it will be returned, rather than fetched.
+func (c Client) RoundTrip(request *Request) (*Response, error) {
+	pc, ok := c.protos[request.Scheme]
+	if !ok {
+		return nil, fmt.Errorf("unrecognized protocol: %s", request.Scheme)
+	}
+	return pc.RoundTrip(request)
+}
+
+// Fetch collects a resource from a URL including following any redirects.
+func (c Client) Fetch(url string) (*Response, error) {
+	u, err := neturl.Parse(url)
+	if err != nil {
+		return nil, err
+	}
+
+	for i := 0; i <= c.MaxRedirects; i += 1 {
+		response, err := c.RoundTrip(&types.Request{URL: u})
+		if err != nil {
+			return nil, err
+		}
+
+		if !c.protos[u.Scheme].IsRedirect(response) {
+			return response, nil
+		}
+
+		prev := u
+		u, err = neturl.Parse(response.Meta.(string))
+		if err != nil {
+			return nil, err
+		}
+		if u.Scheme == "" {
+			u.Scheme = prev.Scheme
+		}
+	}
+
+	return nil, ExceededMaxRedirects
+}