package main

// blueman's applet as the tools see it: its processes, its XDG autostart entry (the package's), the
// applet's own answers on the session bus, and its settings in gsettings. Every bus call is made with
// --auto-start=no: the applet is D-Bus activatable, and a question must never start it.

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

const (
	appletComm = "blueman-applet"
	trayComm   = "blueman-tray"
	appletBin  = "/usr/bin/blueman-applet"
	entryName  = "blueman.desktop"
	restartAs  = "mesh-blueman-applet"
	packageFor = "blueman"
	busName    = "org.blueman.Applet"
	busPath    = "/org/blueman/Applet"
	stackUnit  = "bluetooth.service"
)

// appletCall asks the running applet one question over the session bus and answers busctl's JSON.
func (m *Machine) appletCall(method string) (json.RawMessage, error) {
	args := []string{"--user", "--auto-start=no", "--json=short", "call", busName, busPath, busName, method}
	o := m.cmd(5*time.Second, m.bus(), "busctl", args...)
	if err := failed(o, "busctl", args...); err != nil {
		return nil, err
	}
	var doc struct {
		Data []json.RawMessage `json:"data"`
	}
	if err := json.Unmarshal([]byte(o.Stdout), &doc); err != nil || len(doc.Data) != 1 {
		return nil, fmt.Errorf("the applet's answer to %s is not busctl's JSON: %q", method, tail(o.Stdout, 200))
	}
	return doc.Data[0], nil
}

func (m *Machine) appletStrings(method string) ([]string, error) {
	raw, err := m.appletCall(method)
	if err != nil {
		return nil, err
	}
	var out []string
	if err := json.Unmarshal(raw, &out); err != nil {
		return nil, fmt.Errorf("the applet's %s is not a list of names: %w", method, err)
	}
	sort.Strings(out)
	return out, nil
}

// gvariantStrings reads gsettings' printed array of strings: "@as []" or "['a', '!b']".
func gvariantStrings(s string) []string {
	s = strings.TrimSpace(strings.TrimPrefix(strings.TrimSpace(s), "@as"))
	s = strings.TrimSuffix(strings.TrimPrefix(s, "["), "]")
	out := []string{}
	for _, item := range strings.Split(s, ",") {
		item = strings.Trim(strings.TrimSpace(item), `'"`)
		if item != "" {
			out = append(out, item)
		}
	}
	return out
}

// Plugins is which applet plugins run, and what the operator's settings say about them.
type Plugins struct {
	// Loaded are the plugins the running applet answers it has loaded.
	Loaded []string `json:"loaded"`
	// NotLoaded are the plugins it knows but did not load: switched off, or not fit for this machine.
	NotLoaded []string `json:"not_loaded"`
	// Switched is the operator's plugin-list setting: a name to load it, !name to keep it off. Empty
	// is blueman's defaults.
	Switched []string `json:"switched"`
}

// AppletStatus is what blueman_status answers.
type AppletStatus struct {
	Installed string    `json:"installed,omitempty"`
	Applet    []Proc    `json:"applet"`
	Tray      []Proc    `json:"tray"`
	StartedBy Autostart `json:"started_by"`
	// Bluetooth is the applet's own view of the adapter's power, when it runs.
	Bluetooth *bool   `json:"bluetooth_on,omitempty"`
	Plugins   Plugins `json:"plugins"`
	// Unanswered says why the running applet's view is missing.
	Unanswered string `json:"unanswered,omitempty"`
}

// Status reads the applet: running or not, how it starts, and its plugins.
func (m *Machine) Status() (AppletStatus, error) {
	s := AppletStatus{Applet: m.procs(appletComm), Tray: m.procs(trayComm), StartedBy: m.autostart(entryName),
		Plugins: Plugins{Loaded: []string{}, NotLoaded: []string{}, Switched: []string{}}}
	if s.Applet == nil {
		s.Applet = []Proc{}
	}
	if s.Tray == nil {
		s.Tray = []Proc{}
	}
	if v, err := m.installed(packageFor); err == nil {
		s.Installed = v
	}
	o := m.cmd(5*time.Second, m.bus(), "gsettings", "get", "org.blueman.general", "plugin-list")
	if o.Err == nil && o.Code == 0 {
		s.Plugins.Switched = gvariantStrings(o.Stdout)
	}
	if len(s.Applet) == 0 {
		s.Unanswered = "the applet is not running"
		return s, nil
	}
	loaded, err := m.appletStrings("QueryPlugins")
	if err != nil {
		s.Unanswered = err.Error()
		return s, nil
	}
	s.Plugins.Loaded = loaded
	if all, err := m.appletStrings("QueryAvailablePlugins"); err == nil {
		in := map[string]bool{}
		for _, p := range loaded {
			in[p] = true
		}
		for _, p := range all {
			if !in[p] {
				s.Plugins.NotLoaded = append(s.Plugins.NotLoaded, p)
			}
		}
	}
	if raw, err := m.appletCall("GetBluetoothStatus"); err == nil {
		var on bool
		if json.Unmarshal(raw, &on) == nil {
			s.Bluetooth = &on
		}
	}
	return s, nil
}

// RestartAnswer is what blueman_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 applet and its tray icon, and starts the applet again in the operator's session
// under the account's service manager. The applet starts its tray icon itself.
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.stop(5*time.Second, appletComm, trayComm)
	if err := m.detach(s, restartAs, appletBin); err != nil {
		return a, err
	}
	a.Running = m.waitFor(appletComm, 4*time.Second)
	if len(a.Running) == 0 {
		return a, fmt.Errorf("the applet was started as %s but no %s process appeared within 4 s: "+
			"see `journalctl --user -u %s`", a.Unit, appletComm, a.Unit)
	}
	return a, nil
}

// CheckAnswer is what blueman_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; one start (the package's
// autostart entry, which the session's dex runs); the applet running once in a session; and the
// Bluetooth daemon it manages, which is the bluetooth module's.
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("the package blueman is not installed", "push the module to the node")
	}
	entry := m.autostart(entryName)
	if entry.Starts {
		a.Starts = append(a.Starts, "XDG autostart: "+entry.From)
		if entry.From != "/etc/xdg/autostart/"+entryName {
			add("the account's own "+entry.From+" replaces the package's entry", "remove it, so the package's entry is the one start")
		}
	} else {
		add("the applet does not start with the session ("+entry.Because+")", "remove ~/.config/autostart/"+entryName+" if it hides the package's entry")
	}
	if o := m.cmd(0, nil, "dex", "--version"); o.Err != nil {
		add("dex, which runs the XDG autostart entries at login, is not installed", "assign the i3 module, which installs it and runs it")
	}
	for _, l := range m.i3Starts(appletComm) {
		a.Starts = append(a.Starts, "window manager: "+l)
		add("a second start: "+l, "remove the line; the package's autostart entry is the applet's one start")
	}
	if o := m.cmd(0, nil, "systemctl", "is-active", stackUnit); o.Err != nil || strings.TrimSpace(o.Stdout) != "active" {
		add("the Bluetooth daemon ("+stackUnit+") is not running: the applet has nothing to manage",
			"assign the bluetooth module, which owns bluez and its daemon")
	}
	running := m.procs(appletComm)
	if _, err := m.session(); err == nil {
		switch {
		case len(running) == 0:
			add("no applet runs in the desktop session", "blueman_restart")
		case len(running) > 1:
			add(fmt.Sprintf("%d applets run", len(running)), "blueman_restart ends them all and starts one")
		}
	}
	a.OK = len(a.Findings) == 0
	return a, nil
}