package runner

import (
	"strings"
)

func findStop(sequence string, stops []string) (bool, string) {
	for _, stop := range stops {
		if strings.Contains(sequence, stop) {
			return true, stop
		}
	}

	return false, ""
}

func containsStopSuffix(sequence string, stops []string) bool {
	for _, stop := range stops {
		for i := 1; i <= len(stop); i++ {
			if strings.HasSuffix(sequence, stop[:i]) {
				return true
			}
		}
	}

	return false
}

// truncateStop removes the provided stop string from sequence,
// returning both the truncated sequence and a bool indicating if truncation occurred
func truncateStop(sequence string, stop string) (string, bool) {
	index := strings.Index(sequence, stop)
	if index == -1 {
		return sequence, false
	}

	return sequence[:index], true
}

func incompleteUnicode(token string) bool {
	incomplete := false

	// check if there is incomplete UTF-8 character at the end
	for i := 1; i < 5 && i <= len(token); i++ {
		c := token[len(token)-i]

		if (c & 0xc0) == 0x80 {
			// continuation byte: 10xxxxxx
			continue
		}

		if (c & 0xe0) == 0xc0 {
			// 2-byte character: 110xxxxx ...
			incomplete = i < 2
		} else if (c & 0xf0) == 0xe0 {
			// 3-byte character: 1110xxxx ...
			incomplete = i < 3
		} else if (c & 0xf8) == 0xf0 {
			// 4-byte character: 11110xxx ...
			incomplete = i < 4
		}

		// else 1-byte character or invalid byte
		break
	}

	return incomplete
}