package hostmode

import (
	"bufio"
	"context"
	"log"
	"os"
	"os/exec"
	"strings"
)

// setPXEBootNext points the next boot at a PXE-capable BootOrder
// entry via efibootmgr --bootnext. Best-effort: absent efibootmgr,
// non-UEFI firmware, or zero PXE entries all fall through silently —
// the operator's BIOS/DHCP chain will still PXE-boot on most hosts.
func setPXEBootNext(ctx context.Context) {
	if _, err := os.Stat("/sys/firmware/efi"); err != nil {
		log.Printf("hostmode: not a UEFI system; skipping efibootmgr")
		return
	}
	bin, err := exec.LookPath("efibootmgr")
	if err != nil {
		log.Printf("hostmode: efibootmgr not installed; skipping")
		return
	}
	boots, err := exec.CommandContext(ctx, bin, "-v").Output()
	if err != nil {
		log.Printf("hostmode: efibootmgr -v: %v", err)
		return
	}
	num := findPXEBootNum(string(boots))
	if num == "" {
		log.Printf("hostmode: no PXE boot entry found")
		return
	}
	if err := exec.CommandContext(ctx, bin, "--bootnext", num).Run(); err != nil {
		log.Printf("hostmode: efibootmgr --bootnext %s: %v", num, err)
		return
	}
	log.Printf("hostmode: efibootmgr --bootnext %s", num)
}

// findPXEBootNum picks the first BootXXXX entry whose description
// looks like a network boot. efibootmgr -v output lines look like:
//
//	Boot0003* UEFI: IPv4 Intel I225-V  PciRoot(0x0)/Pci(...)/MAC(...)
//	Boot0001* ubuntu        HD(1,GPT,...)/File(\EFI\ubuntu\shimx64.efi)
func findPXEBootNum(out string) string {
	scan := bufio.NewScanner(strings.NewReader(out))
	for scan.Scan() {
		line := scan.Text()
		if !strings.HasPrefix(line, "Boot") || len(line) < 8 {
			continue
		}
		low := strings.ToLower(line)
		if !(strings.Contains(low, "pxe") ||
			strings.Contains(low, "ipv4") ||
			strings.Contains(low, "ipv6") ||
			strings.Contains(low, "network")) {
			continue
		}
		return line[4:8]
	}
	return ""
}