// Copyright 2018 The CUE Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package strings

import (
	"strings"
	"unicode"
)

// ToTitle returns a copy of the string s with all Unicode letters that begin
// words mapped to their title case.
func ToTitle(s string) string {
	// Use a closure here to remember state.
	// Hackish but effective. Depends on Map scanning in order and calling
	// the closure once per rune.
	prev := ' '
	return strings.Map(
		func(r rune) rune {
			if unicode.IsSpace(prev) {
				prev = r
				return unicode.ToTitle(r)
			}
			prev = r
			return r
		},
		s)
}

// ToCamel returns a copy of the string s with all Unicode letters that begin
// words mapped to lower case.
func ToCamel(s string) string {
	// Use a closure here to remember state.
	// Hackish but effective. Depends on Map scanning in order and calling
	// the closure once per rune.
	prev := ' '
	return strings.Map(
		func(r rune) rune {
			if unicode.IsSpace(prev) {
				prev = r
				return unicode.ToLower(r)
			}
			prev = r
			return r
		},
		s)
}