package utils

import (
	"github.com/gofiber/utils/v2/internal/caseconv"
)

type byteSeq interface {
	~string | ~[]byte
}

// EqualFold tests ascii strings or bytes for equality case-insensitively
func EqualFold[S byteSeq](b, s S) bool {
	if len(b) != len(s) {
		return false
	}

	table := caseconv.ToUpperTable
	n := len(b)
	i := 0

	// Unroll by 4 to match other hot paths and drive instruction-level parallelism.
	limit := n &^ 3
	for i < limit {
		b0 := b[i+0]
		s0 := s[i+0]
		if table[b0] != table[s0] {
			return false
		}

		b1 := b[i+1]
		s1 := s[i+1]
		if table[b1] != table[s1] {
			return false
		}

		b2 := b[i+2]
		s2 := s[i+2]
		if table[b2] != table[s2] {
			return false
		}

		b3 := b[i+3]
		s3 := s[i+3]
		if table[b3] != table[s3] {
			return false
		}

		i += 4
	}

	for i < n {
		if table[b[i]] != table[s[i]] {
			return false
		}
		i++
	}
	return true
}

// TrimLeft is the equivalent of strings/bytes.TrimLeft
func TrimLeft[S byteSeq](s S, cutset byte) S {
	lenStr, start := len(s), 0
	for start < lenStr && s[start] == cutset {
		start++
	}
	return s[start:]
}

// Trim is the equivalent of strings/bytes.Trim
func Trim[S byteSeq](s S, cutset byte) S {
	i, j := 0, len(s)-1
	for ; i <= j; i++ {
		if s[i] != cutset {
			break
		}
	}
	for ; i < j; j-- {
		if s[j] != cutset {
			break
		}
	}

	return s[i : j+1]
}

// TrimRight is the equivalent of strings/bytes.TrimRight
func TrimRight[S byteSeq](s S, cutset byte) S {
	lenStr := len(s)
	for lenStr > 0 && s[lenStr-1] == cutset {
		lenStr--
	}
	return s[:lenStr]
}

// TrimSpace removes leading and trailing whitespace from a string or byte slice.
// This is an optimized version that's faster than strings/bytes.TrimSpace for ASCII strings.
// It removes the following ASCII whitespace characters: space, tab, newline, carriage return, vertical tab, and form feed.
func TrimSpace[S byteSeq](s S) S {
	n := len(s)
	if n == 0 {
		return s
	}

	i, j := 0, n-1
	if !whitespaceTable[s[i]] && !whitespaceTable[s[j]] {
		return s
	}

	// Find first non-whitespace from start
	for ; i <= j && whitespaceTable[s[i]]; i++ { //nolint:revive // we want to check for multiple whitespace chars
	}

	// Find first non-whitespace from end
	for ; i < j && whitespaceTable[s[j]]; j-- { //nolint:revive // we want to check for multiple whitespace chars
	}

	return s[i : j+1]
}