package main

import (
	"context"
	"fmt"
	"os"
	"path/filepath"
	"regexp"
	"strings"
)

// Check is one thing the module expects of the machine, and whether it holds.
type Check struct {
	Name   string `json:"name"`
	OK     bool   `json:"ok"`
	Detail string `json:"detail"`
}

// CheckReport is what zephyrus_check answers. NotChecked says what it did not look at, because a
// check that reads as clean while skipping something is the predecessor's verifier again.
type CheckReport struct {
	Model      string   `json:"model"`
	Checks     []Check  `json:"checks"`
	Failing    int      `json:"failing"`
	NotChecked []string `json:"not_checked"`
}

var (
	pacmanVersion  = regexp.MustCompile(`(?m)^Version\s*:\s*(\S+)`)
	pacmanPackager = regexp.MustCompile(`(?m)^Packager\s*:\s*(.+)$`)
	nvidiaParam    = regexp.MustCompile(`(?m)^(\w+):\s*(\S+)`)
)

// ParseNvidiaParams reads /proc/driver/nvidia/params.
func ParseNvidiaParams(text string) map[string]string {
	out := map[string]string{}
	for _, g := range nvidiaParam.FindAllStringSubmatch(text, -1) {
		out[g[1]] = g[2]
	}
	return out
}

// predecessorProcess finds a running process whose command line names the predecessor's script.
func (m *Machine) predecessorProcess(name string) (int, bool) {
	for _, dir := range m.glob("/proc/[0-9]*") {
		cmd := strings.ReplaceAll(m.read(dir+"/cmdline"), "\x00", " ")
		if strings.Contains(cmd, "/"+name) && !strings.Contains(cmd, "zephyrus") {
			var pid int
			fmt.Sscanf(filepath.Base(dir), "%d", &pid)
			return pid, true
		}
	}
	return 0, false
}

func (m *Machine) unitIs(ctx context.Context, verb, unit string) string {
	out, _ := m.Run(ctx, "systemctl", verb, unit)
	return strings.TrimSpace(out)
}

// Check reads every expectation and reports each.
func (m *Machine) Check(ctx context.Context, sw *Switcher) CheckReport {
	r := CheckReport{Model: m.Model(), NotChecked: []string{
		"the fan curves (asusd's own, read them with zephyrus_fan_curves)",
		"whether the initramfs carries the NVIDIA options (they are read from the running driver instead)",
		"the vendor keys themselves (press them)",
	}}
	add := func(name string, ok bool, format string, a ...any) {
		r.Checks = append(r.Checks, Check{Name: name, OK: ok, Detail: fmt.Sprintf(format, a...)})
		if !ok {
			r.Failing++
		}
	}
	add("model", m.ThisModel(), "the firmware reports %q; this module is for %q", r.Model, ModelFamily)

	// asusctl: present, and from the distribution rather than a local build.
	if info, err := m.Run(ctx, "pacman", "-Qi", "asusctl"); err != nil {
		add("asusctl package", false, "not installed: %v", err)
	} else {
		v, p := "", ""
		if g := pacmanVersion.FindStringSubmatch(info); g != nil {
			v = g[1]
		}
		if g := pacmanPackager.FindStringSubmatch(info); g != nil {
			p = strings.TrimSpace(g[1])
		}
		local := p == "Unknown Packager"
		add("asusctl package", !local, "version %s, packager %s%s", v, p,
			map[bool]string{true: "; a local build — the distribution's package replaces it at the next upgrade (pacman -S asusctl)", false: ""}[local])
	}
	for _, foreign := range []string{"supergfxctl", "triggerhappy"} {
		_, err := m.Run(ctx, "pacman", "-Q", foreign)
		add(foreign+" package", err == nil, "%s; not in the distribution's repositories, kept as found (novox/hq research 027, question 1)",
			map[bool]string{true: "installed", false: "NOT installed"}[err == nil])
	}
	for _, unit := range []string{"asusd.service", "supergfxd.service", "triggerhappy.service"} {
		state := m.unitIs(ctx, "is-active", unit)
		add(unit, state == "active", "%s", state)
	}
	powerd := m.unitIs(ctx, "is-enabled", "nvidia-powerd.service")
	add("nvidia-powerd.service", powerd == "masked" || powerd == "disabled" || powerd == "" || strings.Contains(powerd, "not-found"),
		"%s; the module's drop-in keeps it from starting unless the kernel command line says zephyrus.nvidia-powerd", orNone(powerd))
	wants, _ := m.Run(ctx, "systemctl", "show", "-p", "Wants", "systemd-suspend.service")
	add("nvidia suspend and resume", strings.Contains(wants, "nvidia-suspend.service") && strings.Contains(wants, "nvidia-resume.service"),
		"systemd-suspend.service %s", strings.TrimSpace(wants))

	// The touchpad reset after waking is this module's contribution to node-power's after-wake moment
	// (novox/hq ADR 0211), placed in the power module's moment file under a "# asus-zephyrus-g14" line.
	afterWake := m.read("/etc/mesh-power/moments/after-wake")
	placed := strings.Contains(afterWake, "# asus-zephyrus-g14\n") && strings.Contains(afterWake, "zephyrus-touchpad reset")
	add("touchpad after resume", placed,
		"the reset is placed in the power module's after-wake moment: %v (it needs the power module on this machine)", placed)
	if uid := m.triggerhappyUID(); uid < 0 {
		add("triggerhappy as the account", false, "no thd process runs: the vendor keys do nothing")
	} else {
		add("triggerhappy as the account", uid == operatorUID(), "thd runs as uid %d; the operator's account is %d (the module's drop-in passes --user)", uid, operatorUID())
	}
	refs := m.asUserReferences()
	add("no as-user", len(refs) == 0, "%s", orNone(map[bool]string{true: "", false: "the predecessor's as-user is still named in " + strings.Join(refs, ", ") +
		": it su-s to a named person on a guessed display and sources a file of secrets"}[len(refs) == 0]))

	params := ParseNvidiaParams(m.read("/proc/driver/nvidia/params"))
	if len(params) == 0 {
		add("nvidia options", false, "the NVIDIA driver is not loaded (no /proc/driver/nvidia/params)")
	} else {
		add("nvidia options", params["PreserveVideoMemoryAllocations"] == "1" && params["DynamicPowerManagement"] == "0",
			"PreserveVideoMemoryAllocations=%s DynamicPowerManagement=%s (want 1 and 0; a change applies when the driver loads again)",
			params["PreserveVideoMemoryAllocations"], params["DynamicPowerManagement"])
	}

	for _, b := range m.Batteries() {
		ok := b.LimitPercent != nil && *b.LimitPercent == ChargeLimitPercent
		have := "unknown"
		if b.LimitPercent != nil {
			have = fmt.Sprintf("%d%%", *b.LimitPercent)
		}
		add("charge limit", ok, "%s is %s, the module's is %d%%", b.Name, have, ChargeLimitPercent)
	}

	if c := m.Asusd(); c != nil && (c.ACCommand != "" || c.BatteryCommand != "") {
		add("one authority over the GPU mode", false,
			"asusd runs %q on mains and %q on battery: it switches the GPU mode on every change of power source, "+
				"so a mode set with zephyrus_gpu_mode lasts until the next one. Clear ac_command and bat_command in /etc/asusd/asusd.ron (asusd's file) to make it the operator's alone",
			c.ACCommand, c.BatteryCommand)
	}
	if out, err := m.Run(ctx, "journalctl", "-b", "-u", "supergfxd.service", "-g", "invalid variant", "-n", "1", "-q", "-o", "cat"); err == nil && strings.TrimSpace(out) != "" {
		add("supergfxd and logind", false, "supergfxd cannot read logind's sessions this boot (%s): a mode change that needs a logout times out", strings.TrimSpace(out))
	}

	if pid, ok := m.predecessorProcess("auto-profile"); ok {
		add("one profile switcher", false, "the predecessor's auto-profile still runs (pid %d) and switches the profile every five seconds; "+
			"stop it: systemctl --user disable --now auto-profile.service", pid)
	} else {
		add("one profile switcher", true, "no predecessor auto-profile is running")
	}
	if sw != nil {
		rep := sw.Report()
		add("profile switcher", rep.Running, "%s", orNone(firstNonEmpty(rep.Disabled, rep.LastError, "woken by "+rep.Watching)))
	}
	if home := os.Getenv("MESH_OPERATOR_HOME"); home != "" {
		var left []string
		for _, p := range PredecessorHomeFiles {
			if _, err := os.Stat(filepath.Join(m.Root, home, p)); err == nil {
				left = append(left, "~/"+p)
			}
		}
		add("predecessor files in the home", len(left) == 0, "%s", orNone(strings.Join(left, ", ")))
	} else {
		r.NotChecked = append(r.NotChecked, "the predecessor's files in the operator's home (MESH_OPERATOR_HOME is not set)")
	}
	return r
}

// PredecessorHomeFiles are what the predecessor placed in the operator's home for this model and this
// module replaces. The mesh removes nothing it did not make (novox/hq ADR 0182): the operator does,
// once, and this list is how the check knows.
var PredecessorHomeFiles = []string{
	"scripts/auto-profile",
	".config/systemd/user/auto-profile.service",
	"scripts/asus-bright",
	"scripts/asusctl-kbd-bright",
	"scripts/xrandr-bright",
	"scripts/media-control",
	"scripts/xinput-reset-touchpad",
	".config/i3/scripts/kbd-brightness-notify.sh",
	"scripts/.screenlayouts/orden-workspaces.sh",
}

func orNone(s string) string {
	if strings.TrimSpace(s) == "" {
		return "none"
	}
	return s
}

func firstNonEmpty(ss ...string) string {
	for _, s := range ss {
		if s != "" {
			return s
		}
	}
	return ""
}