package app

import (
	"strings"

	"charm.land/lipgloss/v2"
)

// ansiTruncate — potong string ber-ANSI ke lebar tampilan w (sel), aman
// terhadap escape sequence; bila terpotong ditutup reset + "…".
// Dipakai panel() agar konten tidak pernah wrap (tinggi panel tetap).
func ansiTruncate(s string, w int) string {
	if w <= 0 {
		return ""
	}
	if lipgloss.Width(s) <= w {
		return s
	}
	const (
		stNormal = iota
		stEsc
		stCSI
		stOSC
		stOSCEsc
	)
	state := stNormal
	width := 0
	var b strings.Builder
	for _, r := range s {
		switch state {
		case stNormal:
			if r == 0x1b {
				state = stEsc
				b.WriteRune(r)
				continue
			}
			if width >= w-1 { // sisakan satu sel untuk "…"
				b.WriteString("\x1b[0m…")
				return b.String()
			}
			b.WriteRune(r)
			width++
		case stEsc:
			b.WriteRune(r)
			switch {
			case r == '[':
				state = stCSI
			case r == ']':
				state = stOSC
			case r >= 0x20 && r <= 0x2f:
				// intermediate — tunggu final byte
			default:
				state = stNormal
			}
		case stCSI:
			b.WriteRune(r)
			if r >= 0x40 && r <= 0x7e {
				state = stNormal
			}
		case stOSC:
			b.WriteRune(r)
			if r == 0x07 {
				state = stNormal
			} else if r == 0x1b {
				state = stOSCEsc
			}
		case stOSCEsc:
			b.WriteRune(r)
			if r == '\\' {
				state = stNormal
			} else {
				state = stOSC
			}
		}
	}
	return b.String()
}