Fix Params case handling in the index, sort and where func

This means that you can now do:

```
{{ range where .Site.Pages "Params.MYPARAM" "foo" }}
```

4 files changed, 100 insertions, 66 deletions

diff --git a/common/maps/maps.go b/common/maps/maps.go
index e0d4f964d..8b42ca764 100644
--- a/common/maps/maps.go
+++ b/common/maps/maps.go
@@ -25,26 +25,45 @@ import (
 // recursively.
 // Notes:
 // * This will modify the map given.
-// * Any nested map[interface{}]interface{} will be converted to map[string]interface{}.
-func ToLower(m map[string]interface{}) {
+// * Any nested map[interface{}]interface{} will be converted to Params.
+func ToLower(m Params) {
 	for k, v := range m {
+		var retyped bool
 		switch v.(type) {
 		case map[interface{}]interface{}:
-			v = cast.ToStringMap(v)
-			ToLower(v.(map[string]interface{}))
+			var p Params = cast.ToStringMap(v)
+			v = p
+			ToLower(p)
+			retyped = true
 		case map[string]interface{}:
-			ToLower(v.(map[string]interface{}))
+			var p Params = v.(map[string]interface{})
+			v = p
+			ToLower(p)
+			retyped = true
 		}
 
 		lKey := strings.ToLower(k)
-		if k != lKey {
+		if retyped || k != lKey {
 			delete(m, k)
 			m[lKey] = v
 		}
+	}
+}
 
+func ToStringMapE(in interface{}) (map[string]interface{}, error) {
+	switch in.(type) {
+	case Params:
+		return in.(Params), nil
+	default:
+		return cast.ToStringMapE(in)
 	}
 }
 
+func ToStringMap(in interface{}) map[string]interface{} {
+	m, _ := ToStringMapE(in)
+	return m
+}
+
 type keyRename struct {
 	pattern glob.Glob
 	newKey  string
diff --git a/common/maps/maps_test.go b/common/maps/maps_test.go
index 8b0aa5eb9..6e4947adb 100644
--- a/common/maps/maps_test.go
+++ b/common/maps/maps_test.go
@@ -14,6 +14,7 @@
 package maps
 
 import (
+	"fmt"
 	"reflect"
 	"testing"
 
@@ -21,7 +22,6 @@ import (
 )
 
 func TestToLower(t *testing.T) {
-
 	tests := []struct {
 		input    map[string]interface{}
 		expected map[string]interface{}
@@ -30,7 +30,7 @@ func TestToLower(t *testing.T) {
 			map[string]interface{}{
 				"abC": 32,
 			},
-			map[string]interface{}{
+			Params{
 				"abc": 32,
 			},
 		},
@@ -48,16 +48,16 @@ func TestToLower(t *testing.T) {
 					"J": 25,
 				},
 			},
-			map[string]interface{}{
+			Params{
 				"abc": 32,
-				"def": map[string]interface{}{
+				"def": Params{
 					"23": "A value",
-					"24": map[string]interface{}{
+					"24": Params{
 						"abcde": "A value",
 						"efghi": "Another value",
 					},
 				},
-				"ghi": map[string]interface{}{
+				"ghi": Params{
 					"j": 25,
 				},
 			},
@@ -65,11 +65,13 @@ func TestToLower(t *testing.T) {
 	}
 
 	for i, test := range tests {
-		// ToLower modifies input.
-		ToLower(test.input)
-		if !reflect.DeepEqual(test.expected, test.input) {
-			t.Errorf("[%d] Expected\n%#v, got\n%#v\n", i, test.expected, test.input)
-		}
+		t.Run(fmt.Sprint(i), func(t *testing.T) {
+			// ToLower modifies input.
+			ToLower(test.input)
+			if !reflect.DeepEqual(test.expected, test.input) {
+				t.Errorf("[%d] Expected\n%#v, got\n%#v\n", i, test.expected, test.input)
+			}
+		})
 	}
 }
 
diff --git a/common/maps/params.go b/common/maps/params.go
index 2d62ad752..ecb63d7a5 100644
--- a/common/maps/params.go
+++ b/common/maps/params.go
@@ -19,76 +19,89 @@ import (
 	"github.com/spf13/cast"
 )
 
+// Params is a map where all keys are lower case.
+type Params map[string]interface{}
+
+// Get does a lower case and nested search in this map.
+// It will return nil if none found.
+func (p Params) Get(indices ...string) interface{} {
+	v, _, _ := getNested(p, indices)
+	return v
+}
+
+func getNested(m map[string]interface{}, indices []string) (interface{}, string, map[string]interface{}) {
+	if len(indices) == 0 {
+		return nil, "", nil
+	}
+
+	first := indices[0]
+	v, found := m[strings.ToLower(cast.ToString(first))]
+	if !found {
+		return nil, "", nil
+	}
+
+	if len(indices) == 1 {
+		return v, first, m
+	}
+
+	switch m2 := v.(type) {
+	case Params:
+		return getNested(m2, indices[1:])
+	case map[string]interface{}:
+		return getNested(m2, indices[1:])
+	default:
+		return nil, "", nil
+	}
+}
+
 // GetNestedParam gets the first match of the keyStr in the candidates given.
 // It will first try the exact match and then try to find it as a nested map value,
 // using the given separator, e.g. "mymap.name".
 // It assumes that all the maps given have lower cased keys.
-func GetNestedParam(keyStr, separator string, candidates ...map[string]interface{}) (interface{}, error) {
+func GetNestedParam(keyStr, separator string, candidates ...Params) (interface{}, error) {
 	keyStr = strings.ToLower(keyStr)
 
-	lookupFn := func(key string) interface{} {
-		for _, m := range candidates {
-			if v, ok := m[key]; ok {
-				return v
-			}
+	// Try exact match first
+	for _, m := range candidates {
+		if v, ok := m[keyStr]; ok {
+			return v, nil
 		}
-
-		return nil
-	}
-
-	v, _, _, err := GetNestedParamFn(keyStr, separator, lookupFn)
-	return v, err
-}
-
-func GetNestedParamFn(keyStr, separator string, lookupFn func(key string) interface{}) (interface{}, string, map[string]interface{}, error) {
-	result, _ := traverseDirectParams(keyStr, lookupFn)
-	if result != nil {
-		return result, keyStr, nil, nil
 	}
 
 	keySegments := strings.Split(keyStr, separator)
-	if len(keySegments) == 1 {
-		return nil, keyStr, nil, nil
+	for _, m := range candidates {
+		if v := m.Get(keySegments...); v != nil {
+			return v, nil
+		}
 	}
 
-	return traverseNestedParams(keySegments, lookupFn)
-}
+	return nil, nil
 
-func traverseDirectParams(keyStr string, lookupFn func(key string) interface{}) (interface{}, error) {
-	return lookupFn(keyStr), nil
 }
 
-func traverseNestedParams(keySegments []string, lookupFn func(key string) interface{}) (interface{}, string, map[string]interface{}, error) {
-	firstKey, rest := keySegments[0], keySegments[1:]
-	result := lookupFn(firstKey)
-	if result == nil || len(rest) == 0 {
-		return result, firstKey, nil, nil
+func GetNestedParamFn(keyStr, separator string, lookupFn func(key string) interface{}) (interface{}, string, map[string]interface{}, error) {
+	keySegments := strings.Split(strings.ToLower(keyStr), separator)
+	if len(keySegments) == 0 {
+		return nil, "", nil, nil
 	}
 
-	switch m := result.(type) {
-	case map[string]interface{}:
-		v, key, owner := traverseParams(rest, m)
-		return v, key, owner, nil
-	default:
+	first := lookupFn(keySegments[0])
+	if first == nil {
 		return nil, "", nil, nil
 	}
-}
-
-func traverseParams(keys []string, m map[string]interface{}) (interface{}, string, map[string]interface{}) {
-	// Shift first element off.
-	firstKey, rest := keys[0], keys[1:]
-	result := m[firstKey]
 
-	// No point in continuing here.
-	if result == nil {
-		return result, "", nil
+	if len(keySegments) == 1 {
+		return first, keySegments[0], nil, nil
 	}
 
-	if len(rest) == 0 {
-		// That was the last key.
-		return result, firstKey, m
+	switch m := first.(type) {
+	case map[string]interface{}:
+		v, key, owner := getNested(m, keySegments[1:])
+		return v, key, owner, nil
+	case Params:
+		v, key, owner := getNested(m, keySegments[1:])
+		return v, key, owner, nil
 	}
 
-	// That was not the last key.
-	return traverseParams(rest, cast.ToStringMap(result))
+	return nil, "", nil, nil
 }
diff --git a/common/maps/params_test.go b/common/maps/params_test.go
index 6477de6f4..8016a8bd6 100644
--- a/common/maps/params_test.go
+++ b/common/maps/params_test.go
@@ -35,7 +35,7 @@ func TestGetNestedParam(t *testing.T) {
 
 	c := qt.New(t)
 
-	must := func(keyStr, separator string, candidates ...map[string]interface{}) interface{} {
+	must := func(keyStr, separator string, candidates ...Params) interface{} {
 		v, err := GetNestedParam(keyStr, separator, candidates...)
 		c.Assert(err, qt.IsNil)
 		return v