// SPDX-FileCopyrightText: (C) Copyright 2026 Pim van Pelt <pim@ipng.ch>
// SPDX-License-Identifier: Apache-2.0

//go:build openbsd

package cli

import (
	"os"

	"github.com/chzyer/readline"
	"golang.org/x/sys/unix"
)

// applyTermFuncs makes readline drive the terminal through golang.org/x/sys/unix.
//
// chzyer/readline's own termios handling (term_bsd.go) issues raw
// syscall.Syscall6(SYS_IOCTL, ...) calls. OpenBSD forbids direct syscalls from
// outside libc, so those return ENOSYS: readline's IsTerminal() then reports
// false and the REPL silently degrades to a dumb line reader -- no prompt, no
// tab completion. x/sys/unix performs the same ioctls through libc.
//
// The raw-mode flag set below is copied verbatim from readline's own MakeRaw
// (term.go), and that match matters: it deliberately leaves OPOST enabled, so a
// command's "\n" output is still translated to "\r\n". A full cfmakeraw (e.g.
// golang.org/x/term.MakeRaw) clears OPOST and staircases multi-line output.
// Only OpenBSD needs this; every other platform keeps readline's native path.
func applyTermFuncs(cfg *readline.Config) {
	stdin := int(os.Stdin.Fd())
	stdout := int(os.Stdout.Fd())
	var saved *unix.Termios

	cfg.FuncIsTerminal = func() bool {
		_, err := unix.IoctlGetTermios(stdin, unix.TIOCGETA)
		return err == nil
	}
	cfg.FuncMakeRaw = func() error {
		old, err := unix.IoctlGetTermios(stdin, unix.TIOCGETA)
		if err != nil {
			return err
		}
		saved = old
		raw := *old
		raw.Iflag &^= unix.IGNBRK | unix.BRKINT | unix.PARMRK | unix.ISTRIP | unix.INLCR | unix.IGNCR | unix.ICRNL | unix.IXON
		// OPOST is intentionally left set (see the doc comment above).
		raw.Lflag &^= unix.ECHO | unix.ECHONL | unix.ICANON | unix.ISIG | unix.IEXTEN
		raw.Cflag &^= unix.CSIZE | unix.PARENB
		raw.Cflag |= unix.CS8
		raw.Cc[unix.VMIN] = 1
		raw.Cc[unix.VTIME] = 0
		return unix.IoctlSetTermios(stdin, unix.TIOCSETA, &raw)
	}
	cfg.FuncExitRaw = func() error {
		if saved == nil {
			return nil
		}
		err := unix.IoctlSetTermios(stdin, unix.TIOCSETA, saved)
		saved = nil
		return err
	}
	cfg.FuncGetWidth = func() int {
		ws, err := unix.IoctlGetWinsize(stdout, unix.TIOCGWINSZ)
		if err != nil || ws.Col == 0 {
			return 80 // sane default when the width can't be read
		}
		return int(ws.Col)
	}
}