package core

import (
	"regexp"
	"strings"
)

// ansiCSI matches CSI sequences: ESC [ ... <final byte>
// Covers colors (SGR), cursor movement, erase, etc.
var ansiCSI = regexp.MustCompile(`\x1b\[[0-9;?]*[ -/]*[@-~]`)

// ansiOSC matches OSC sequences: ESC ] ... <BEL or ST>
// Used for window titles, hyperlinks, etc.
var ansiOSC = regexp.MustCompile(`\x1b\][^\x07\x1b]*(\x07|\x1b\\)`)

// ansiEsc matches other two-character escape sequences: ESC <char>
// Covers ESC c (reset), ESC ( B, ESC ) 0, etc.
var ansiEsc = regexp.MustCompile(`\x1b[@-Z\\-_]|\x1b[()][0-9A-Za-z]`)

// StripANSI removes ANSI/VT100 terminal escape sequences from s and filters
// non-printable control characters, preserving newlines (\n), tabs (\t) and
// carriage returns (\r).
func StripANSI(s string) string {
	s = ansiCSI.ReplaceAllString(s, "")
	s = ansiOSC.ReplaceAllString(s, "")
	s = ansiEsc.ReplaceAllString(s, "")
	return strings.Map(func(r rune) rune {
		// Preserve printable characters, \n (0x0A), \t (0x09), \r (0x0D).
		if r == '\n' || r == '\t' || r == '\r' {
			return r
		}
		// Drop C0 control characters (0x00-0x1F) and DEL (0x7F).
		if r < 0x20 || r == 0x7F {
			return -1
		}
		return r
	}, s)
}