/*
 * Copyright (c) 2024 The GoPlus Authors (goplus.org). All rights reserved.
 *
 * 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 safesplit

import "strings"

// SplitPkgConfigFlags splits a pkg-config outputs string into parts.
// Each part starts with "-" followed by a single character flag.
// Spaces after the flag character are ignored.
// Content is read until the next space, unless escaped with "\".
func SplitPkgConfigFlags(s string) []string {
	var result []string
	var current strings.Builder
	i := 0

	// Skip leading whitespace
	for i < len(s) && (s[i] == ' ' || s[i] == '\t') {
		i++
	}

	for i < len(s) {
		// Start a new part
		if current.Len() > 0 {
			result = append(result, strings.TrimSpace(current.String()))
			current.Reset()
		}
		// Write "-" and the flag character
		current.WriteByte('-')
		i++
		if i < len(s) {
			current.WriteByte(s[i])
			i++
		}
		// Skip spaces after flag character
		for i < len(s) && (s[i] == ' ' || s[i] == '\t') {
			i++
		}
		// Read content until next space
		for i < len(s) {
			if s[i] == '\\' && i+1 < len(s) && (s[i+1] == ' ' || s[i+1] == '\t') {
				// Skip backslash and write the escaped space
				i++
				current.WriteByte(s[i])
				i++
				continue
			}
			if s[i] == ' ' || s[i] == '\t' {
				// Skip consecutive spaces
				j := i
				for j < len(s) && (s[j] == ' ' || s[j] == '\t') {
					j++
				}
				// If we've seen content, check for new flag
				if j < len(s) && s[j] == '-' {
					i = j
					break
				}
				// Otherwise, include one space and continue
				current.WriteByte(' ')
				i = j
			} else {
				current.WriteByte(s[i])
				i++
			}
		}
	}
	// Add the last part
	if current.Len() > 0 {
		result = append(result, strings.TrimSpace(current.String()))
	}
	return result
}