package main

// Polychromatic's tray as the tools see it: its processes, its one start (the module's line in the
// window manager's configuration), the package's login helper and the one setting of the application's
// that makes the helper start the tray too, and whether the daemon it drives answers. The daemon is
// the openrazer module's; it is asked with --auto-start=no, so a question never starts it.

import (
	"encoding/json"
	"fmt"
	"strings"
	"time"
)

const (
	trayComm    = "polychromatic-t" // the kernel keeps 15 characters of polychromatic-tray-applet
	trayWord    = "polychromatic-tray-applet"
	trayBin     = "/usr/bin/polychromatic-tray-applet"
	helperEntry = "polychromatic-autostart.desktop"
	restartAs   = "mesh-polychromatic-tray"
	packageFor  = "polychromatic"
	prefsFile   = ".config/polychromatic/preferences.json"
	settingName = "Preferences → Tray → \"Start the tray applet when I log on\""
)

// trays are the tray's processes. Its cut command name is this bundle's own too, so the program is
// matched by its full name.
func (m *Machine) trays() []Proc { return m.procsOf(trayComm, trayWord) }

// TraySetting is the application's own setting that makes its login helper start the tray. The
// module never writes it: the application rewrites its preferences file itself.
type TraySetting struct {
	// Autostart is the setting; Polychromatic's default is on.
	Autostart bool   `json:"autostart"`
	Delay     int    `json:"autostart_delay_seconds"`
	From      string `json:"from"`
}

// setting reads the tray keys of the preferences file and nothing else of it.
func (m *Machine) setting() TraySetting {
	s := TraySetting{Autostart: true, From: "Polychromatic's default (no preferences file)"}
	raw, err := readBounded(m.home(prefsFile))
	if err != nil {
		return s
	}
	var doc struct {
		Tray struct {
			Autostart *bool `json:"autostart"`
			Delay     int   `json:"autostart_delay"`
		} `json:"tray"`
	}
	if err := json.Unmarshal(raw, &doc); err != nil {
		s.From = "Polychromatic's default (the preferences file does not parse)"
		return s
	}
	s.From = "~/" + prefsFile
	if doc.Tray.Autostart != nil {
		s.Autostart = *doc.Tray.Autostart
	}
	s.Delay = doc.Tray.Delay
	return s
}

// Backend is whether the openrazer daemon answers, and how many devices it has.
type Backend struct {
	Answers    bool   `json:"answers"`
	Devices    int    `json:"devices"`
	Unanswered string `json:"unanswered,omitempty"`
}

func (m *Machine) backend() Backend {
	args := []string{"--user", "--auto-start=no", "--json=short", "call", "org.razer", "/org/razer", "razer.devices", "getDevices"}
	o := m.cmd(5*time.Second, m.bus(), "busctl", args...)
	if err := failed(o, "busctl", args...); err != nil {
		return Backend{Unanswered: "the openrazer daemon does not answer (asked without starting it): " + err.Error()}
	}
	var doc struct {
		Data [][]string `json:"data"`
	}
	if err := json.Unmarshal([]byte(o.Stdout), &doc); err != nil || len(doc.Data) != 1 {
		return Backend{Unanswered: "the daemon's device list is not busctl's JSON"}
	}
	return Backend{Answers: true, Devices: len(doc.Data[0])}
}

// foreign says whether the package came from outside the official repositories (pacman -Qm).
func (m *Machine) foreign() bool {
	o := m.cmd(0, nil, "pacman", "-Qqm", packageFor)
	return o.Err == nil && o.Code == 0 && strings.TrimSpace(o.Stdout) == packageFor
}

// StatusAnswer is what polychromatic_status answers.
type StatusAnswer struct {
	Installed string      `json:"installed,omitempty"`
	Foreign   bool        `json:"outside_official_repositories"`
	Tray      []Proc      `json:"tray"`
	StartedBy []string    `json:"started_by"`
	Helper    Autostart   `json:"login_helper"`
	Setting   TraySetting `json:"tray_setting"`
	Backend   Backend     `json:"backend"`
}

// Status reads the tray, what starts it, and whether the daemon behind it answers.
func (m *Machine) Status() (StatusAnswer, error) {
	s := StatusAnswer{Tray: m.trays(), StartedBy: []string{}, Helper: m.autostart(helperEntry),
		Setting: m.setting(), Backend: m.backend()}
	if s.Tray == nil {
		s.Tray = []Proc{}
	}
	v, err := m.installed(packageFor)
	if err != nil {
		return s, err
	}
	s.Installed = v
	if v != "" {
		s.Foreign = m.foreign()
	}
	for _, l := range m.i3Starts(trayWord) {
		s.StartedBy = append(s.StartedBy, "window manager: "+l)
	}
	if s.Helper.Starts && s.Setting.Autostart {
		s.StartedBy = append(s.StartedBy, "the login helper ("+s.Helper.From+"), as the tray setting is on")
	}
	return s, nil
}

// RestartAnswer is what polychromatic_restart answers.
type RestartAnswer struct {
	Ended   []int   `json:"ended"`
	Killed  []int   `json:"killed,omitempty"`
	Running []Proc  `json:"running"`
	Session Session `json:"session"`
	Unit    string  `json:"unit"`
}

// Restart ends the tray and starts it again in the operator's session, under the account's service
// manager.
func (m *Machine) Restart() (RestartAnswer, error) {
	s, err := m.session()
	if err != nil {
		return RestartAnswer{}, err
	}
	a := RestartAnswer{Session: s, Unit: restartAs + ".service"}
	a.Ended, a.Killed = m.stopProcs(5*time.Second, m.trays())
	if err := m.detach(s, restartAs, trayBin); err != nil {
		return a, err
	}
	a.Running = m.waitForOf(trayComm, trayWord, 4*time.Second)
	if len(a.Running) == 0 {
		return a, fmt.Errorf("the tray was started as %s but no %s process appeared within 4 s: "+
			"see `journalctl --user -u %s`", a.Unit, trayWord, a.Unit)
	}
	return a, nil
}

// CheckAnswer is what polychromatic_check answers.
type CheckAnswer struct {
	OK       bool      `json:"ok"`
	Findings []Finding `json:"findings"`
	Starts   []string  `json:"starts"`
}

// Check verifies what the module promises and relies on: the package (found, not installed by the
// mesh); one start, the module's window-manager line; the tray running once; and the daemon answering.
func (m *Machine) Check() (CheckAnswer, error) {
	a := CheckAnswer{Findings: []Finding{}, Starts: []string{}}
	add := func(what, do string) { a.Findings = append(a.Findings, Finding{what, do}) }
	v, err := m.installed(packageFor)
	if err != nil {
		return a, err
	}
	if v == "" {
		add("polychromatic is not installed. It is outside the official repositories, so the mesh does not install it",
			"install it from the AUR by hand; it brings the openrazer packages with it")
	}

	lines := m.i3Starts(trayWord)
	for _, l := range lines {
		a.Starts = append(a.Starts, "window manager: "+l)
	}
	switch {
	case len(lines) == 0:
		add("the window manager does not start the tray", "push the module: its line in the window manager's configuration is the tray's start")
	case len(lines) > 1:
		for _, l := range lines[1:] {
			add("a second start: "+l, "remove the line; the module's line is the tray's one start")
		}
	}
	helper := m.autostart(helperEntry)
	if set := m.setting(); helper.Starts && set.Autostart {
		a.Starts = append(a.Starts, "login helper: "+helper.From+" (the tray setting is on)")
		add("a second start: the package's login helper starts the tray too, as the tray setting is on ("+set.From+")",
			"in Polychromatic, untick "+settingName+". The helper keeps its other work: it resumes the devices' effects")
	}
	if own := m.autostart(trayWord + ".desktop"); own.Starts {
		a.Starts = append(a.Starts, "XDG autostart: "+own.From)
		add("a second start: "+own.From, "remove it; the module's line is the tray's one start")
	}

	if _, err := m.session(); err == nil {
		switch running := m.trays(); {
		case len(running) == 0:
			add("no tray runs in the desktop session", "polychromatic_restart")
		case len(running) > 1:
			add(fmt.Sprintf("%d trays run", len(running)), "polychromatic_restart ends them all and starts one")
		}
	}
	if b := m.backend(); !b.Answers {
		add(b.Unanswered+": the tray has no devices to show", "assign the openrazer module; openrazer_check says why the daemon is not running")
	}
	a.OK = len(a.Findings) == 0
	return a, nil
}