package detection

import (
	"sync"
	"testing"
	"time"
)

func TestScorer_EmptyInput(t *testing.T) {
	s := NewScorer()
	score := s.Score()
	if score != 0 {
		t.Errorf("empty scorer: got %f, want 0", score)
	}
}

func TestScorer_SingleKeystroke(t *testing.T) {
	s := NewScorer()
	s.RecordEvent(time.Now(), DirInput, []byte("a"))
	score := s.Score()
	if score != 0 {
		t.Errorf("single keystroke: got %f, want 0", score)
	}
}

func TestScorer_BotLikeInput(t *testing.T) {
	// Simulate a bot: paste entire commands with uniform tiny delays, no special keys.
	s := NewScorer()
	now := time.Now()

	// Bot pastes "cat /etc/passwd\r" all at once with perfectly uniform timing.
	for range 3 {
		cmd := []byte("cat /etc/passwd\r")
		for _, b := range cmd {
			s.RecordEvent(now, DirInput, []byte{b})
			now = now.Add(100 * time.Microsecond) // ~0.1ms uniform delay = paste
		}
	}

	score := s.Score()
	if score >= 0.3 {
		t.Errorf("bot-like input: got %f, want < 0.3", score)
	}
}

func TestScorer_HumanLikeInput(t *testing.T) {
	// Simulate a human: variable timing, backspaces, diverse commands.
	s := NewScorer()
	now := time.Now()

	type cmd struct {
		text  string
		delay time.Duration // base delay between keys
	}

	commands := []cmd{
		{"ls -la\r", 80 * time.Millisecond},
		{"cat /etc/paswd", 120 * time.Millisecond}, // typo
		{string([]byte{0x7f}), 200 * time.Millisecond},  // backspace
		{"wd\r", 90 * time.Millisecond},                  // correction
		{"whoami\r", 100 * time.Millisecond},
		{"uname -a\r", 150 * time.Millisecond},
		{string([]byte{0x09}), 300 * time.Millisecond}, // tab completion
		{"pwd\r", 70 * time.Millisecond},
	}

	for _, c := range commands {
		for _, b := range []byte(c.text) {
			// Add ±30% jitter to make timing more natural.
			jitter := time.Duration(float64(c.delay) * 0.3)
			delay := c.delay + jitter // simplified: always add, still variable across commands
			s.RecordEvent(now, DirInput, []byte{b})
			now = now.Add(delay)
		}
		// Pause between commands (thinking time).
		now = now.Add(2 * time.Second)
	}

	score := s.Score()
	if score <= 0.6 {
		t.Errorf("human-like input: got %f, want > 0.6", score)
	}
}

func TestScorer_OutputIgnored(t *testing.T) {
	s := NewScorer()
	now := time.Now()

	// Only output events — should not affect score.
	for i := 0; i < 100; i++ {
		s.RecordEvent(now, DirOutput, []byte("some output\n"))
		now = now.Add(10 * time.Millisecond)
	}

	score := s.Score()
	if score != 0 {
		t.Errorf("output-only: got %f, want 0", score)
	}
}

func TestScorer_ThreadSafety(t *testing.T) {
	s := NewScorer()
	now := time.Now()

	var wg sync.WaitGroup
	for i := 0; i < 10; i++ {
		wg.Add(1)
		go func(offset int) {
			defer wg.Done()
			for j := 0; j < 100; j++ {
				ts := now.Add(time.Duration(offset*100+j) * time.Millisecond)
				s.RecordEvent(ts, DirInput, []byte("a"))
			}
		}(i)
	}

	// Concurrently read score.
	wg.Add(1)
	go func() {
		defer wg.Done()
		for i := 0; i < 50; i++ {
			_ = s.Score()
		}
	}()

	wg.Wait()

	// Should not panic; score should be valid.
	score := s.Score()
	if score < 0 || score > 1 {
		t.Errorf("concurrent score out of range: %f", score)
	}
}

func TestScorer_CommandDiversity(t *testing.T) {
	s := NewScorer()
	now := time.Now()

	// Type 4 different commands with human-ish timing.
	cmds := []string{"ls\r", "pwd\r", "id\r", "whoami\r"}
	for _, cmd := range cmds {
		for _, b := range []byte(cmd) {
			s.RecordEvent(now, DirInput, []byte{b})
			now = now.Add(100 * time.Millisecond)
		}
		now = now.Add(time.Second)
	}

	score := s.Score()
	// With 4 unique commands, human timing, and decent duration,
	// we should get a meaningful score.
	if score < 0.4 {
		t.Errorf("diverse commands: got %f, want >= 0.4", score)
	}
}