package main

import (
	"context"
	"fmt"
	"regexp"
	"strconv"
	"strings"
)

// The vendor daemons are reached through their own command-line clients, which speak to them on the
// system bus. Their bus policy admits the `users` and `wheel` groups, so none of this needs root.

// Profiles are the platform profiles asusd offers on this model, in its spelling.
var Profiles = []string{"Quiet", "Balanced", "Performance"}

// canonicalProfile accepts any case and answers asusd's spelling, or an error naming the choices.
func canonicalProfile(s string) (string, error) {
	for _, p := range Profiles {
		if strings.EqualFold(strings.TrimSpace(s), p) {
			return p, nil
		}
	}
	return "", fmt.Errorf("profile %q is not one of %s", s, strings.Join(Profiles, ", "))
}

// ProfileState is what asusd says about the platform profile.
type ProfileState struct {
	Active   string `json:"active"`
	OnAC     string `json:"on_ac,omitempty"`
	Battery  string `json:"on_battery,omitempty"`
	Platform string `json:"platform_profile,omitempty"`
	Choices  string `json:"platform_profile_choices,omitempty"`
}

var (
	activeProfile  = regexp.MustCompile(`(?m)^Active profile:\s*(\S+)`)
	acProfile      = regexp.MustCompile(`(?m)^AC profile\s+(\S+)`)
	batteryProfile = regexp.MustCompile(`(?m)^Battery profile\s+(\S+)`)
)

// ParseProfileGet reads `asusctl profile get`.
func ParseProfileGet(out string) (ProfileState, error) {
	var p ProfileState
	if m := activeProfile.FindStringSubmatch(out); m != nil {
		p.Active = m[1]
	} else {
		return p, fmt.Errorf("asusctl profile get said no active profile: %q", strings.TrimSpace(out))
	}
	if m := acProfile.FindStringSubmatch(out); m != nil {
		p.OnAC = m[1]
	}
	if m := batteryProfile.FindStringSubmatch(out); m != nil {
		p.Battery = m[1]
	}
	return p, nil
}

// Profile reads the platform profile from asusd and the kernel.
func (m *Machine) Profile(ctx context.Context) (ProfileState, error) {
	out, err := m.Run(ctx, "asusctl", "profile", "get")
	if err != nil {
		return ProfileState{}, vendor("asusctl", err)
	}
	p, err := ParseProfileGet(out)
	if err != nil {
		return p, err
	}
	p.Platform = m.read("/sys/firmware/acpi/platform_profile")
	p.Choices = m.read("/sys/firmware/acpi/platform_profile_choices")
	return p, nil
}

// SetProfile has asusd switch the active profile.
func (m *Machine) SetProfile(ctx context.Context, profile string) error {
	_, err := m.Run(ctx, "asusctl", "profile", "set", profile)
	return vendor("asusctl", err)
}

var chargeLimit = regexp.MustCompile(`charge limit:\s*(\d+)\s*%`)

// ChargeLimit is the battery's charge limit as asusd reports it.
func (m *Machine) ChargeLimit(ctx context.Context) (int, error) {
	out, err := m.Run(ctx, "asusctl", "battery", "info")
	if err != nil {
		return 0, vendor("asusctl", err)
	}
	g := chargeLimit.FindStringSubmatch(out)
	if g == nil {
		return 0, fmt.Errorf("asusctl battery info said no limit: %q", strings.TrimSpace(out))
	}
	n, _ := strconv.Atoi(g[1])
	return n, nil
}

// Keyboard backlight levels in asusd's spelling, index = the kernel's brightness value.
var KeyboardLevels = []string{"off", "low", "med", "high"}

var ledLevel = regexp.MustCompile(`(?i)brightness:\s*(off|low|med|high)`)

// ParseLeds reads `asusctl leds get`.
func ParseLeds(out string) (string, error) {
	g := ledLevel.FindStringSubmatch(out)
	if g == nil {
		return "", fmt.Errorf("asusctl leds get said no level: %q", strings.TrimSpace(out))
	}
	return strings.ToLower(g[1]), nil
}

// FanCurve is one fan's curve in one profile: eight points of temperature (°C) and duty (0-255).
type FanCurve struct {
	Fan     string `json:"fan"`
	Enabled bool   `json:"enabled"`
	Temp    []int  `json:"temp_c"`
	PWM     []int  `json:"pwm"`
}

var (
	fanBlock = regexp.MustCompile(`(?s)fan:\s*(\w+),\s*pwm:\s*\(([^)]*)\),\s*temp:\s*\(([^)]*)\),\s*enabled:\s*(true|false)`)
)

// ParseFanCurves reads `asusctl fan-curve --mod-profile <p>`.
func ParseFanCurves(out string) []FanCurve {
	var curves []FanCurve
	for _, g := range fanBlock.FindAllStringSubmatch(out, -1) {
		curves = append(curves, FanCurve{Fan: g[1], PWM: ints(g[2]), Temp: ints(g[3]), Enabled: g[4] == "true"})
	}
	return curves
}

func ints(list string) []int {
	var out []int
	for _, f := range strings.Split(list, ",") {
		if n, err := strconv.Atoi(strings.TrimSpace(f)); err == nil {
			out = append(out, n)
		}
	}
	return out
}

// GPUState is what supergfxd says about the hybrid GPU.
type GPUState struct {
	Mode          string   `json:"mode"`
	Supported     []string `json:"supported"`
	Power         string   `json:"dgpu_power,omitempty"`
	PendingAction string   `json:"pending_action,omitempty"`
	PendingMode   string   `json:"pending_mode,omitempty"`
	Vendor        string   `json:"dgpu_vendor,omitempty"`
}

// ParseSupported reads `supergfxctl -s`: `[Integrated, Hybrid, AsusMuxDgpu]`.
func ParseSupported(out string) []string {
	out = strings.Trim(strings.TrimSpace(out), "[]")
	var modes []string
	for _, f := range strings.Split(out, ",") {
		if f = strings.TrimSpace(f); f != "" {
			modes = append(modes, f)
		}
	}
	return modes
}

// GPU reads supergfxd.
func (m *Machine) GPU(ctx context.Context) (GPUState, error) {
	var g GPUState
	mode, err := m.Run(ctx, "supergfxctl", "-g")
	if err != nil {
		return g, vendor("supergfxctl", err)
	}
	g.Mode = strings.TrimSpace(mode)
	if s, err := m.Run(ctx, "supergfxctl", "-s"); err == nil {
		g.Supported = ParseSupported(s)
	}
	if s, err := m.Run(ctx, "supergfxctl", "-S"); err == nil {
		g.Power = strings.TrimSpace(s)
	}
	if s, err := m.Run(ctx, "supergfxctl", "-p"); err == nil {
		g.PendingAction = strings.TrimSpace(s)
	}
	if s, err := m.Run(ctx, "supergfxctl", "-P"); err == nil {
		g.PendingMode = strings.TrimSpace(s)
	}
	if s, err := m.Run(ctx, "supergfxctl", "-V"); err == nil {
		g.Vendor = strings.TrimSpace(s)
	}
	return g, nil
}

// vendor names a vendor client that is not installed, rather than passing on "executable file not
// found". asusctl is in the distribution's repositories; supergfxctl is not, and the module keeps it as
// it was found until the mesh can build packages from the user repository (research 027, question 1).
func vendor(name string, err error) error {
	if err == nil {
		return nil
	}
	if notInstalled(err) {
		switch name {
		case "supergfxctl":
			return fmt.Errorf("supergfxctl is not installed: it is not in the distribution's repositories, " +
				"and this module keeps the copy it finds rather than install one (novox/hq research 027, question 1)")
		default:
			return fmt.Errorf("%s is not installed; the module's package resource installs it", name)
		}
	}
	return err
}

// AsusdConfig is the few settings of asusd's own file that decide what this module's code does. The
// file is asusd's: it rewrites it whenever a setting changes, so the module reads it and never writes
// it.
type AsusdConfig struct {
	ChargeLimit          *int   `json:"charge_control_end_threshold,omitempty"`
	ProfileOnAC          string `json:"platform_profile_on_ac,omitempty"`
	ProfileOnBattery     string `json:"platform_profile_on_battery,omitempty"`
	ChangesProfileOnAC   *bool  `json:"change_platform_profile_on_ac,omitempty"`
	ChangesProfileOnBatt *bool  `json:"change_platform_profile_on_battery,omitempty"`
	ACCommand            string `json:"ac_command,omitempty"`
	BatteryCommand       string `json:"bat_command,omitempty"`
	DisablesPowerdOnBatt *bool  `json:"disable_nvidia_powerd_on_battery,omitempty"`
}

var ronField = regexp.MustCompile(`(?m)^\s{4}([a-z_]+):\s*(.*?),?\s*$`)

// ParseAsusdRon reads the top-level scalar fields of asusd.ron. RON is not a format the mesh
// speaks; these are one line each, and nothing nested is read.
func ParseAsusdRon(text string) AsusdConfig {
	var c AsusdConfig
	for _, g := range ronField.FindAllStringSubmatch(text, -1) {
		key, value := g[1], strings.TrimSuffix(strings.TrimSpace(g[2]), ",")
		unquoted := strings.Trim(value, `"`)
		boolean := func() *bool { b := value == "true"; return &b }
		switch key {
		case "charge_control_end_threshold":
			if n, err := strconv.Atoi(value); err == nil {
				c.ChargeLimit = &n
			}
		case "platform_profile_on_ac":
			c.ProfileOnAC = unquoted
		case "platform_profile_on_battery":
			c.ProfileOnBattery = unquoted
		case "change_platform_profile_on_ac":
			c.ChangesProfileOnAC = boolean()
		case "change_platform_profile_on_battery":
			c.ChangesProfileOnBatt = boolean()
		case "ac_command":
			c.ACCommand = unquoted
		case "bat_command":
			c.BatteryCommand = unquoted
		case "disable_nvidia_powerd_on_battery":
			c.DisablesPowerdOnBatt = boolean()
		}
	}
	return c
}

// Asusd reads asusd's file; nil when it is not there.
func (m *Machine) Asusd() *AsusdConfig {
	text := m.read("/etc/asusd/asusd.ron")
	if text == "" {
		return nil
	}
	c := ParseAsusdRon(text)
	return &c
}