http and registry work

Author: pjdufour

pkg/http/ErrNotNegotiable.go

@@ -0,0 +1,22 @@
+// =================================================================
+//
+// Copyright (C) 2019 Spatial Current, Inc. - All Rights Reserved
+// Released as open source under the MIT License.  See LICENSE file.
+//
+// =================================================================
+
+package http
+
+import (
+	"fmt"
+)
+
+// ErrNotNegotiable is used when the server cannot negotiate a format given an accept header.
+type ErrNotNegotiable struct {
+	Value string // the name of the unknown format
+}
+
+// Error returns the error formatted as a string.
+func (e ErrNotNegotiable) Error() string {
+	return fmt.Sprintf("could not negotiate format from string %q", e.Value)
+}

pkg/http/Ext.go

@@ -0,0 +1,36 @@
+// =================================================================
+//
+// Copyright (C) 2019 Spatial Current, Inc. - All Rights Reserved
+// Released as open source under the MIT License.  See LICENSE file.
+//
+// =================================================================
+
+package http
+
+import (
+	"net/http"
+	"path/filepath"
+
+	"github.com/pkg/errors"
+)
+
+var (
+	ErrMissingURL = errors.New("missing URL")
+)
+
+// Ext returns the file name extension in the URL path.
+// The extension begins after the last period in the file element of the path.
+// If no period is in the last element or a period is the last character, then returns a blank string.
+func Ext(r *http.Request) (string, error) {
+	if r.URL == nil {
+		return "", ErrMissingURL
+	}
+	ext := filepath.Ext(r.URL.Path)
+	if len(ext) == 0 {
+		return "", nil
+	}
+	if ext == "." {
+		return "", nil
+	}
+	return ext[1:], nil
+}

pkg/http/NegotiateFormat.go

@@ -0,0 +1,83 @@
+// =================================================================
+//
+// Copyright (C) 2019 Spatial Current, Inc. - All Rights Reserved
+// Released as open source under the MIT License.  See LICENSE file.
+//
+// =================================================================
+
+package http
+
+import (
+	"net/http"
+	"sort"
+	"strconv"
+	"strings"
+
+	"github.com/pkg/errors"
+
+	"github.com/spatialcurrent/go-simple-serializer/pkg/registry"
+)
+
+var (
+	ErrMissingAcceptHeader = errors.New("missing accept header")
+	ErrMissingRegistry     = errors.New("missing file type registry")
+)
+
+// NegotiateFormat negotitates the format for the response based on the incoming request and the given file type registry.
+// Returns the matching content type, followed by the format known to GSS, and then an error if any.
+func NegotiateFormat(r *http.Request, reg *registry.Registry) (string, string, error) {
+
+	accept := strings.TrimSpace(r.Header.Get(HeaderAccept))
+
+	if len(accept) == 0 {
+		return "", "", ErrMissingAcceptHeader
+	}
+
+	if reg == nil {
+		return "", "", ErrMissingRegistry
+	}
+
+	// Parse accept header into map of weights to accepted values
+	values := map[float64][]string{}
+	for _, str := range strings.SplitN(accept, ",", -1) {
+		v := strings.TrimSpace(str)
+		if strings.Contains(v, ";q=") {
+			parts := strings.SplitN(v, ";q=", 2)
+			w, err := strconv.ParseFloat(parts[1], 64)
+			if err != nil {
+				return "", "", errors.Wrapf(err, "could not parse quality value for value %q", v)
+			}
+			if _, ok := values[w]; !ok {
+				values[w] = make([]string, 0)
+			}
+			values[w] = append(values[w], strings.TrimSpace(parts[0]))
+
+		} else {
+			if _, ok := values[1.0]; !ok {
+				values[1.0] = make([]string, 0)
+			}
+			values[1.0] = append(values[1.0], v)
+		}
+	}
+
+	// Create list of weights
+	weights := make([]float64, 0, len(values))
+	for w := range values {
+		weights = append(weights, w)
+	}
+
+	// Sort by weigt in descending order
+	sort.SliceStable(weights, func(i, j int) bool {
+		return weights[i] > weights[j]
+	})
+
+	// Iterate through accepted values in order of highest weight first
+	for _, w := range weights {
+		for _, contentType := range values[w] {
+			if item, ok := reg.LookupContentType(contentType); ok {
+				return contentType, item.Format, nil
+			}
+		}
+	}
+	return "", "", &ErrNotNegotiable{Value: accept}
+}

pkg/http/NegotiateFormat_test.go

@@ -0,0 +1,47 @@
+// =================================================================
+//
+// Copyright (C) 2019 Spatial Current, Inc. - All Rights Reserved
+// Released as open source under the MIT License.  See LICENSE file.
+//
+// =================================================================
+
+package http
+
+import (
+	"net/http/httptest"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/spatialcurrent/go-simple-serializer/pkg/serializer"
+)
+
+func TestNegotiateFormatJSON(t *testing.T) {
+	reg := NewDefaultRegistry()
+	r := httptest.NewRequest("GET", "https://example.com/foo/bar", nil)
+	r.Header.Set("Accept", "application/json")
+	c, f, err := NegotiateFormat(r, reg)
+	assert.NoError(t, err)
+	assert.Equal(t, "application/json", c)
+	assert.Equal(t, serializer.FormatJSON, f)
+}
+
+func TestNegotiateFormatBSON(t *testing.T) {
+	reg := NewDefaultRegistry()
+	r := httptest.NewRequest("GET", "https://example.com/foo/bar", nil)
+	r.Header.Set("Accept", "application/ubjson, application/json")
+	c, f, err := NegotiateFormat(r, reg)
+	assert.NoError(t, err)
+	assert.Equal(t, "application/ubjson", c)
+	assert.Equal(t, serializer.FormatBSON, f)
+}
+
+func TestNegotiateFormatWeight(t *testing.T) {
+	reg := NewDefaultRegistry()
+	r := httptest.NewRequest("GET", "https://example.com/foo/bar", nil)
+	r.Header.Set("Accept", "text/csv;q=0.8, application/json;q=0.9")
+	c, f, err := NegotiateFormat(r, reg)
+	assert.NoError(t, err)
+	assert.Equal(t, "application/json", c)
+	assert.Equal(t, serializer.FormatJSON, f)
+}

pkg/http/Respond.go

@@ -0,0 +1,45 @@
+// =================================================================
+//
+// Copyright (C) 2019 Spatial Current, Inc. - All Rights Reserved
+// Released as open source under the MIT License.  See LICENSE file.
+//
+// =================================================================
+
+package http
+
+import (
+	"net/http"
+
+	"github.com/pkg/errors"
+
+	"github.com/spatialcurrent/go-simple-serializer/pkg/registry"
+	"github.com/spatialcurrent/go-simple-serializer/pkg/serializer"
+)
+
+// Respond writes the given data to the respond writer, and returns an error if any.
+// If filename is not empty, then the "Content-Disposition" header is set to "attachment; filename=<FILENAME>".
+func Respond(w http.ResponseWriter, r *http.Request, reg *registry.Registry, data interface{}, status int, filename string) error {
+
+	contentType, format, err := NegotiateFormat(r, reg)
+	if err != nil {
+		ext, err := Ext(r)
+		if err != nil || len(ext) == 0 {
+			return errors.Errorf("could not negotiate format or parse file extension from %#v", r)
+		}
+		if item, ok := reg.LookupExtension(ext); ok {
+			contentType = item.ContentTypes[0]
+			format = item.Format
+		} else {
+			return errors.Errorf("could not negotiate format or parse file extension from %#v", r)
+		}
+	}
+
+	s := serializer.New(format)
+
+	body, err := s.Serialize(data)
+	if err != nil {
+		return errors.Wrap(err, "error serializing response body")
+	}
+
+	return RespondWithContent(w, body, contentType, status, filename)
+}

pkg/http/RespondWithContent.go

@@ -0,0 +1,37 @@
+// =================================================================
+//
+// Copyright (C) 2019 Spatial Current, Inc. - All Rights Reserved
+// Released as open source under the MIT License.  See LICENSE file.
+//
+// =================================================================
+
+package http
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/pkg/errors"
+)
+
+// RespondWithContent writes the given content to the response writer, and returns an error if any.
+// If filename is not empty, then the "Content-Disposition" header is set to "attachment; filename=<FILENAME>".
+func RespondWithContent(w http.ResponseWriter, body []byte, contentType string, status int, filename string) error {
+
+	if len(filename) > 0 {
+		w.Header().Set("Content-Disposition", fmt.Sprintf("attachment; filename=%s", filename))
+	}
+
+	w.Header().Set("Content-Type", contentType)
+
+	if status != http.StatusOK {
+		w.WriteHeader(status)
+	}
+
+	_, err := w.Write(body)
+	if err != nil {
+		return errors.Wrap(err, "error writing response body")
+	}
+
+	return nil
+}