// Copyright 2024 The Dawn & Tint Authors.
//
// Redistribution and use in source and binary forms, with or without
// modification, are permitted provided that the following conditions are met:
//
//  1. Redistributions of source code must retain the above copyright notice, this
//     list of conditions and the following disclaimer.
//
//  2. Redistributions in binary form must reproduce the above copyright notice,
//     this list of conditions and the following disclaimer in the documentation
//     and/or other materials provided with the distribution.
//
//  3. Neither the name of the copyright holder nor the names of its
//     contributors may be used to endorse or promote products derived from
//     this software without specific prior written permission.
//
// THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
// AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
// IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
// DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
// FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
// DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
// SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
// CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
// OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
// OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.

package text

import (
	"strings"
	"unicode"
)

// PascalCase returns the snake-case string s transformed into 'PascalCase',
// Rules:
// * The first letter of the string is capitalized
// * Characters following an underscore or number are capitalized
// * Underscores are removed from the returned string
// See: https://en.wikipedia.org/wiki/Camel_case
func PascalCase(s string) string {
	b := strings.Builder{}
	upper := true
	for _, r := range s {
		if r == '_' || r == ' ' {
			upper = true
			continue
		}
		if upper {
			b.WriteRune(unicode.ToUpper(r))
			upper = false
		} else {
			b.WriteRune(r)
		}
		if unicode.IsNumber(r) {
			upper = true
		}
	}
	return b.String()
}

// SnakeCase returns the pascal-case or camel-case string s transformed into 'snake_case',
// Rules:
// * Characters following a lower-case to upper-case transition has a '_' inserted
// * All emitted characters are lowered
// See: https://en.wikipedia.org/wiki/Snake_case
func SnakeCase(s string) string {
	b := strings.Builder{}
	wasUpper := true
	for _, r := range s {
		nowUpper := unicode.IsUpper(r) || unicode.IsNumber(r)
		if !wasUpper && nowUpper {
			b.WriteRune('_')
		}
		b.WriteRune(unicode.ToLower(r))
		wasUpper = nowUpper
	}
	return b.String()
}