package pxe

import (
	"fmt"
	"io"
	"strings"

	"vetting/internal/model"
)

// IPXEParams is everything an iPXE boot script needs.
// For Phase 2 the boot target is always "linux" — Memtest chain-load
// is not required because we replaced Memtest86+ with stress-ng under
// Linux (see plan §3.2).
type IPXEParams struct {
	OrchestratorURL string // e.g. http://10.0.0.5:8080
	LiveKernelURL   string // e.g. http://10.0.0.5:8080/live/vmlinuz
	LiveInitrdURL   string // e.g. http://10.0.0.5:8080/live/initrd.img
	TLSCertFPR      string // optional; empty = skip pin
	RunID           int64
	MAC             string
	Token           string // plaintext, hashed on server side
}

// BuildScript returns an iPXE script tailored for this run.
// iPXE scripts are plain text beginning with "#!ipxe".
func BuildScript(p IPXEParams) string {
	cmdline := []string{
		"initrd=initrd.img",
		fmt.Sprintf("vetting.orchestrator=%s", p.OrchestratorURL),
		fmt.Sprintf("vetting.run_id=%d", p.RunID),
		fmt.Sprintf("vetting.mac=%s", p.MAC),
		fmt.Sprintf("vetting.token=%s", p.Token),
	}
	if p.TLSCertFPR != "" {
		cmdline = append(cmdline, fmt.Sprintf("vetting.cert_fpr=%s", p.TLSCertFPR))
	}
	// Verbose kernel + systemd logging on both the video console and the
	// serial port so first-boot failures on unfamiliar hardware aren't
	// invisible. Drop `quiet` entirely — once boot is stable we can
	// re-add it. systemd.log_target=kmsg makes early systemd go through
	// the same dmesg buffer as the kernel, so nothing is lost before
	// journald comes up.
	cmdline = append(cmdline,
		"console=tty0",
		"console=ttyS0,115200n8",
		"ip=dhcp",
		"loglevel=7",
		"systemd.log_level=info",
		"systemd.log_target=kmsg",
		"systemd.journald.forward_to_console=1",
		// systemd-getty-generator sees console=ttyS0 and creates
		// serial-getty@ttyS0.service, which waits up to 90s for
		// /dev/ttyS0 to appear. Hosts without a serial port time
		// out and delay boot. Mask the getty — kernel logs still
		// tee to ttyS0 if the port exists, we just don't spawn
		// a login prompt there.
		"systemd.mask=serial-getty@ttyS0.service",
		// systemd-firstboot.service is the interactive "first boot
		// wizard" (locale/timezone/root-password prompts). In a
		// PXE live image there's no operator at the console to
		// answer, so it blocks sysinit.target forever and the
		// agent never comes up. systemd.firstboot=off short-
		// circuits it entirely.
		"systemd.firstboot=off",
	)

	var b strings.Builder
	fmt.Fprintln(&b, "#!ipxe")
	fmt.Fprintf(&b, "echo Vetting run %d — booting live image for %s\n", p.RunID, p.MAC)
	fmt.Fprintf(&b, "kernel %s %s\n", p.LiveKernelURL, strings.Join(cmdline, " "))
	fmt.Fprintf(&b, "initrd %s\n", p.LiveInitrdURL)
	fmt.Fprintln(&b, "boot")
	return b.String()
}

// NotRegisteredScript is served for unknown MACs. The MAC allowlist
// at the dnsmasq level should prevent this from ever being reachable,
// but it exists as belt-and-braces.
func NotRegisteredScript(mac string) string {
	return fmt.Sprintf("#!ipxe\necho MAC %s not registered for vetting — halting.\nshell\n", mac)
}

// NoActiveRunScript is served when a registered MAC PXE-boots but has
// no currently active run. The host is told to shut down rather than
// loop forever.
func NoActiveRunScript(mac string) string {
	return fmt.Sprintf("#!ipxe\necho MAC %s has no active run — powering off in 10s.\nsleep 10\npoweroff\n", mac)
}

// Used by handlers to compose URLs; exposed for tests.
func BuildLiveURLs(base string) (kernel, initrd string) {
	base = strings.TrimRight(base, "/")
	return base + "/live/vmlinuz", base + "/live/initrd.img"
}

// WriteNotFound is a small convenience so handlers can return a shell
// script error directly to iPXE without cluttering handlers with a
// mime-type dance.
func WriteNotFound(w io.Writer, mac string) {
	_, _ = w.Write([]byte(NotRegisteredScript(mac)))
}

// ScriptMarker is used by iPXE to detect that the response is a script.
const ScriptMarker = "#!ipxe"

// State returns the compact single-word status used for logging.
// Takes a Run's state because iPXE handler already looked it up.
func State(run model.Run) string { return string(run.State) }