package main

import (
	"context"
	"fmt"
	"sort"
	"strings"
)

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

// Check says what this module expects and whether the machine meets it: its units in place and
// enabled, the runner and the moment files present, logind's file the mesh's, the inhibitor held,
// and the predecessor's leftovers.
func (m *Machine) Check(ctx context.Context, w *Watcher) map[string]any {
	var checks []Check
	add := func(name string, ok bool, format string, args ...any) {
		checks = append(checks, Check{Name: name, OK: ok, Detail: fmt.Sprintf(format, args...)})
	}
	units := make([]string, 0, len(Units))
	for u := range Units {
		units = append(units, u)
	}
	sort.Strings(units)
	for _, u := range units {
		present := m.exists("/etc/systemd/system/" + u)
		enabled, _ := m.Run(ctx, "systemctl", "is-enabled", u)
		enabled = strings.TrimSpace(enabled)
		want := "enabled"
		switch u {
		case "mesh-power-supply.service":
			want = "static" // started by the udev rule, never by a target
		case "mesh-power-before-sleep.service", "mesh-power-after-wake.service":
			want = "static" // wanted by the sleep targets through the module's drop-ins, never enabled
		}
		add(u, present && enabled == want, "%s: file present %v, %s (want %s)", Units[u], present, orWord(enabled, "unknown"), want)
	}
	add("runner", m.exists(RunnerPath), "%s present: %v", RunnerPath, m.exists(RunnerPath))
	for _, moment := range Moments {
		p := MomentsDir + "/" + moment
		add("moment "+moment, m.exists(p), "%s placed: %v, %d piece(s)", p, m.exists(p), len(Pieces(m.read(p)+"\n")))
	}
	logind := m.read(LogindFile)
	add("logind's power file", strings.Contains(logind, "module power"), "%s is the mesh's (module power): %v",
		LogindFile, strings.Contains(logind, "module power"))
	var others []string
	for _, f := range m.glob("/etc/systemd/logind.conf.d/*.conf") {
		if f != LogindFile {
			others = append(others, f)
		}
	}
	add("one writer of logind's power handling", len(others) == 0,
		"other logind drop-ins: %s (novox/hq ADR 0210: logind's power settings are this module's alone)", orWord(strings.Join(others, ", "), "none"))
	hooks := m.glob("/etc/systemd/system-sleep/*")
	add("no hand-placed sleep hooks", len(hooks) == 0,
		"%s (code around sleep is a contribution to node-power now, novox/hq ADR 0211)", orWord(strings.Join(hooks, ", "), "none"))
	add("udev rule", m.exists(UdevRule) || Source(m.Supplies()) == "none", "%s present: %v (only acts where there is a Mains supply)", UdevRule, m.exists(UdevRule))
	if w != nil {
		s := w.Snapshot()
		add("sleep inhibitor", s.Inhibiting, "delay lock on sleep and shutdown held by the watcher: %v%s", s.Inhibiting, orNote(s.Problem))
		add("events reach the bus", s.Pending == 0, "%d event(s) waiting for the bus", s.Pending)
	}
	failing := 0
	for _, c := range checks {
		if !c.OK {
			failing++
		}
	}
	return map[string]any{"checks": checks, "failing": failing,
		"not_checked": []string{"that a contribution's own code does what it means (power_run runs one moment now)"}}
}

func orWord(s, word string) string {
	if strings.TrimSpace(s) == "" {
		return word
	}
	return s
}

func orNote(s string) string {
	if s == "" {
		return ""
	}
	return " (" + s + ")"
}