package main

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

// Key is one custom key on the laptop: what it is, what runs, and where that is defined.
type Key struct {
	Key      string `json:"key"`
	Physical string `json:"physical,omitempty"`
	When     string `json:"when,omitempty"`
	Runs     string `json:"runs"`
	From     string `json:"from"`
}

// KeysReport is what zephyrus_keys answers.
type KeysReport struct {
	Keys     []Key    `json:"keys"`
	Warnings []string `json:"warnings"`
	NotRead  []string `json:"not_read"`
}

// TriggerDir is triggerhappy's directory of trigger files; the module owns one file in it.
const TriggerDir = "/etc/triggerhappy/triggers.d"

// I3Config is the window manager's configuration, relative to the account's home. This module's lines
// are its contribution to node-display-session (novox/hq ADR 0212), placed there by the i3 module
// under a line that names this module.
const I3Config = ".config/i3/config"

// ModuleName is the line the controller writes before this module's contributed lines.
const ModuleName = "asus-zephyrus-g14"

// ownSection is this module's contributed lines in a placed file: from the line naming it to the next
// line naming another module, a section header, or the file's end.
func ownSection(text string) []string {
	var out []string
	in := false
	for _, line := range strings.Split(text, "\n") {
		t := strings.TrimSpace(line)
		if t == "# "+ModuleName {
			in = true
			continue
		}
		if !in {
			continue
		}
		if strings.HasPrefix(t, "####") || (strings.HasPrefix(t, "# ") && isModuleLine(strings.TrimPrefix(t, "# "))) {
			break
		}
		out = append(out, line)
	}
	return out
}

// isModuleLine is a comment that is one catalogue module's name: lower case, digits and dashes.
func isModuleLine(s string) bool {
	if s == "" {
		return false
	}
	for _, r := range s {
		if !(r >= 'a' && r <= 'z' || r >= '0' && r <= '9' || r == '-') {
			return false
		}
	}
	return true
}

// physicalKeys names the key behind an evdev code, as far as it is known on this model. The media
// codes are the M4 key and Fn+F4/F5 together; which code is which key was not recorded.
var physicalKeys = map[string]string{
	"KEY_PROG1":          "a media key (M4, Fn+F4 or Fn+F5)",
	"KEY_PROG3":          "a media key (M4, Fn+F4 or Fn+F5)",
	"KEY_PROG4":          "a media key (M4, Fn+F4 or Fn+F5)",
	"KEY_BRIGHTNESSDOWN": "Fn+F7",
	"KEY_BRIGHTNESSUP":   "Fn+F8",
	"KEY_F21":            "Fn+F10 (touchpad)",
	"$mod+Shift+s":       "Fn+F6 (screenshot; the firmware sends Super+Shift+S)",
	"$mod+p":             "Fn+F9 (display; the firmware sends Super+P)",
}

// firmwareKeys are handled below any configuration file.
var firmwareKeys = []Key{
	{Key: "Fn+F2 / Fn+F3", Physical: "keyboard backlight", Runs: "the firmware and asusd; zephyrus-kbd-notify shows the level", From: "firmware"},
}

var (
	triggerLine = regexp.MustCompile(`^(\S+)\s+([0-9]+)\s+(.+)$`)
	i3Bind      = regexp.MustCompile(`^bindsym\s+((?:--\S+\s+)*)(\S+)\s+(.+)$`)
	i3Exec      = regexp.MustCompile(`^exec(?:_always)?\s+(?:--no-startup-id\s+)?(.+)$`)
)

var triggerWhen = map[string]string{"0": "released", "1": "pressed", "2": "held (repeat)"}

// Keys lists the laptop's custom keys: every triggerhappy trigger, the module's i3 lines and the keys
// the firmware handles itself.
func (m *Machine) Keys() KeysReport {
	r := KeysReport{Keys: []Key{}, Warnings: []string{}, NotRead: []string{}}
	seen := map[string][]string{}
	files := m.glob(TriggerDir + "/*.conf")
	sort.Strings(files)
	if len(files) == 0 {
		r.Warnings = append(r.Warnings, "no trigger file in "+TriggerDir+": the vendor keys do nothing")
	}
	for _, f := range files {
		for _, line := range strings.Split(m.read(f), "\n") {
			line = strings.TrimSpace(line)
			if line == "" || strings.HasPrefix(line, "#") {
				continue
			}
			g := triggerLine.FindStringSubmatch(line)
			if g == nil {
				continue
			}
			r.Keys = append(r.Keys, Key{Key: g[1], Physical: physicalKeys[g[1]], When: triggerWhen[g[2]], Runs: g[3], From: f})
			id := g[1] + " " + g[2]
			seen[id] = append(seen[id], f)
		}
	}
	for id, fs := range seen {
		if len(fs) > 1 {
			r.Warnings = append(r.Warnings, fmt.Sprintf("%s is bound in %d places (%s): it fires every one", id, len(fs), strings.Join(fs, ", ")))
		}
	}
	home := os.Getenv("MESH_OPERATOR_HOME")
	if home == "" {
		r.NotRead = append(r.NotRead, "the module's i3 lines (MESH_OPERATOR_HOME is not set)")
	}
	if home != "" {
		lines := ownSection(m.read(filepath.Join(home, I3Config)))
		if len(lines) == 0 {
			r.Warnings = append(r.Warnings, "~/"+I3Config+" holds no lines of this module's: is the i3 module assigned and pushed?")
		}
		from := "~/" + I3Config + " (" + ModuleName + "'s contribution)"
		for _, line := range lines {
			line = strings.TrimSpace(line)
			if g := i3Bind.FindStringSubmatch(line); g != nil {
				when := "pressed"
				if strings.Contains(g[1], "--release") {
					when = "released"
				}
				r.Keys = append(r.Keys, Key{Key: g[2], Physical: physicalKeys[g[2]], When: when, Runs: strings.TrimPrefix(strings.TrimPrefix(g[3], "exec "), "--no-startup-id "), From: from})
			} else if g := i3Exec.FindStringSubmatch(line); g != nil {
				r.Keys = append(r.Keys, Key{Key: "(session start)", When: "at login", Runs: g[1], From: from})
			}
		}
	}
	r.Keys = append(r.Keys, firmwareKeys...)
	sort.Strings(r.Warnings)
	return r
}

// asUserReferences finds the predecessor's as-user wrapper still named in a trigger, a udev rule or
// the module's i3 lines.
func (m *Machine) asUserReferences() []string {
	var at []string
	for _, pattern := range []string{TriggerDir + "/*.conf", "/etc/udev/rules.d/*.rules", "/etc/systemd/system-sleep/*"} {
		for _, f := range m.glob(pattern) {
			if strings.Contains(m.read(f), "as-user") {
				at = append(at, f)
			}
		}
	}
	sort.Strings(at)
	return at
}

// triggerhappyUID is the real user id the running thd has, or -1 when none runs.
func (m *Machine) triggerhappyUID() int {
	for _, dir := range m.glob("/proc/[0-9]*") {
		if strings.TrimSpace(m.read(dir+"/comm")) != "thd" {
			continue
		}
		for _, line := range strings.Split(m.read(dir+"/status"), "\n") {
			if f := strings.Fields(line); len(f) >= 2 && f[0] == "Uid:" {
				var uid int
				if _, err := fmt.Sscanf(f[1], "%d", &uid); err == nil {
					return uid
				}
			}
		}
	}
	return -1
}

// operatorUID is the account the module's code runs as: the runtime runs it as the operator's.
var operatorUID = os.Getuid