package main

import (
	"context"
	"os"
	"os/exec"
	"path/filepath"
	"strings"
	"sync"
	"testing"
)

// fake is a machine for a test: a tree standing in for /, and a runner answering from a table and
// recording every command it was asked to run.
type fake struct {
	t       *testing.T
	root    string
	mu      sync.Mutex
	answers map[string]string
	fails   map[string]error
	calls   []string
}

func newFake(t *testing.T) *fake {
	t.Helper()
	return &fake{t: t, root: t.TempDir(), answers: map[string]string{}, fails: map[string]error{}}
}

func (f *fake) machine() *Machine { return &Machine{Root: f.root, Run: f.run} }

func (f *fake) run(_ context.Context, name string, args ...string) (string, error) {
	line := strings.TrimSpace(name + " " + strings.Join(args, " "))
	f.mu.Lock()
	defer f.mu.Unlock()
	f.calls = append(f.calls, line)
	if err, ok := f.fails[line]; ok {
		return "", err
	}
	if out, ok := f.answers[line]; ok {
		return out, nil
	}
	if err, ok := f.fails[name]; ok {
		return "", err
	}
	return "", nil
}

func (f *fake) called(line string) bool {
	f.mu.Lock()
	defer f.mu.Unlock()
	for _, c := range f.calls {
		if c == line {
			return true
		}
	}
	return false
}

func (f *fake) callsLike(prefix string) []string {
	f.mu.Lock()
	defer f.mu.Unlock()
	var out []string
	for _, c := range f.calls {
		if strings.HasPrefix(c, prefix) {
			out = append(out, c)
		}
	}
	return out
}

// file writes a file under the fake root.
func (f *fake) file(path, content string) {
	f.t.Helper()
	full := filepath.Join(f.root, path)
	if err := os.MkdirAll(filepath.Dir(full), 0o755); err != nil {
		f.t.Fatal(err)
	}
	if err := os.WriteFile(full, []byte(content), 0o644); err != nil {
		f.t.Fatal(err)
	}
}

// supply writes one power supply's attributes.
func (f *fake) supply(name string, attrs map[string]string) {
	for k, v := range attrs {
		f.file("/sys/class/power_supply/"+name+"/"+k, v+"\n")
	}
}

// onMains and onBattery are this model's two states as measured on 2026-10-04.
func (f *fake) onMains() {
	f.supply("ACAD", map[string]string{"type": "Mains", "online": "1"})
	f.supply("BAT1", map[string]string{"type": "Battery", "status": "Not charging", "capacity": "80"})
}

func (f *fake) onBattery() {
	f.supply("ACAD", map[string]string{"type": "Mains", "online": "0"})
	f.supply("BAT1", map[string]string{"type": "Battery", "status": "Discharging", "capacity": "79"})
}

var notFound = &exec.Error{Name: "x", Err: exec.ErrNotFound}

const profileGetBalanced = "Active profile: Balanced\n\nAC profile Balanced\nBattery profile Quiet\n"