allow more flexibility in specifying options

Options can be specified in any order (size no longer needs to be listed
first), and may be repeated.  Duplicated options overwrite previous
values.  Technically, non-size options could already be repeated... now
size can as well.  There's really not much value to this, it's just an
side-effect of allowing any order.

fixes #5

proxy/data.go

@@ -61,27 +61,9 @@ func (o Options) String() string {
 
 func ParseOptions(str string) *Options {
 	o := new(Options)
-	var h, w string
 
 	parts := strings.Split(str, ",")
-
+	for _, part := range parts {
-	// parse size
-	size := strings.SplitN(parts[0], "x", 2)
-	w = size[0]
-	if len(size) > 1 {
-		h = size[1]
-	} else {
-		h = w
-	}
-
-	if w != "" {
-		o.Width, _ = strconv.ParseFloat(w, 64)
-	}
-	if h != "" {
-		o.Height, _ = strconv.ParseFloat(h, 64)
-	}
-
-	for _, part := range parts[1:] {
 		if part == "fit" {
 			o.Fit = true
 			continue
@@ -95,10 +77,35 @@ func ParseOptions(str string) *Options {
 			continue
 		}
 
-		if len(part) > 2 && strings.HasPrefix(part, "r") {
+		if len(part) > 2 && part[:1] == "r" {
 			o.Rotate, _ = strconv.Atoi(part[1:])
 			continue
 		}
+
+		if strings.ContainsRune(part, 'x') {
+			var h, w string
+			size := strings.SplitN(part, "x", 2)
+			w = size[0]
+			if len(size) > 1 {
+				h = size[1]
+			} else {
+				h = w
+			}
+
+			if w != "" {
+				o.Width, _ = strconv.ParseFloat(w, 64)
+			}
+			if h != "" {
+				o.Height, _ = strconv.ParseFloat(h, 64)
+			}
+			continue
+		}
+
+		if size, err := strconv.ParseFloat(part, 64); err == nil {
+			o.Width = size
+			o.Height = size
+			continue
+		}
 	}
 
 	return o

proxy/data_test.go

@@ -46,6 +46,7 @@ func TestParseOptions(t *testing.T) {
 		{"", emptyOptions},
 		{"x", emptyOptions},
 		{"0", emptyOptions},
+		{",,,,", emptyOptions},
 
 		// size variations
 		{"1x", &Options{Width: 1}},
@@ -54,12 +55,23 @@ func TestParseOptions(t *testing.T) {
 		{"0.1x0.2", &Options{Width: 0.1, Height: 0.2}},
 
 		// additional flags
-		{",fit", &Options{Fit: true}},
+		{"fit", &Options{Fit: true}},
-		{",r90", &Options{Rotate: 90}},
+		{"r90", &Options{Rotate: 90}},
-		{",fv", &Options{FlipVertical: true}},
+		{"fv", &Options{FlipVertical: true}},
-		{",fh", &Options{FlipHorizontal: true}},
+		{"fh", &Options{FlipHorizontal: true}},
+
+		// duplicate flags (last one wins)
+		{"1x2,3x4", &Options{Width: 3, Height: 4}},
+		{"1x2,3", &Options{Width: 3, Height: 3}},
+		{"1x2,0x3", &Options{Width: 0, Height: 3}},
+		{"1x,x2", &Options{Width: 1, Height: 2}},
+		{"r90,r270", &Options{Rotate: 270}},
+
+		// mix of valid and invalid flags
+		{"FOO,1,BAR,r90,BAZ", &Options{Width: 1, Height: 1, Rotate: 90}},
 
 		{"1x2,fit,r90,fv,fh", &Options{1, 2, true, 90, true, true}},
+		{"r90,fh,1x2,fv,fit", &Options{1, 2, true, 90, true, true}},
 	}
 
 	for i, tt := range tests {

readme.md

@@ -24,9 +24,10 @@ imageproxy URLs are of the form `http://localhost/{options}/{remote_url}`.
 
 ### Options ###
 
-Options are specified as a comma delimited list of parameters, the first of
+Options are specified as a comma delimited list of parameters, which can be
-which always specifies image size.  The format is a superset of [resize.ly's
+supplied in any order.  Duplicate parameters overwrite previous values.  
-options](https://resize.ly/#demo).
+
+The format is a superset of [resize.ly's options](https://resize.ly/#demo).
 
 #### Size ####