package store

import (
	"errors"
	"testing"
	"time"
)

func TestAddHeartbeat_FirstSetsFirstLastAndCount(t *testing.T) {
	s := New(nil)
	id := DeviceID("device-1")
	t0 := time.Date(2024, 1, 1, 12, 0, 0, 0, time.UTC)

	if err := s.AddHeartbeat(id, t0); err != nil {
		t.Fatalf("AddHeartbeat: %v", err)
	}
	if got := s.Uptime(id); got != 100 {
		t.Fatalf("uptime = %v, want 100 (1 beat / 1 minute)", got)
	}
}

func TestAddHeartbeat_LaterUpdatesLast(t *testing.T) {
	s := New(nil)
	id := DeviceID("device-1")
	t0 := time.Date(2024, 1, 1, 12, 0, 0, 0, time.UTC)
	t1 := t0.Add(time.Minute)

	_ = s.AddHeartbeat(id, t0)
	if err := s.AddHeartbeat(id, t1); err != nil {
		t.Fatalf("AddHeartbeat: %v", err)
	}
	// (2 beats / 1 minute) * 100
	if got := s.Uptime(id); got != 200 {
		t.Fatalf("uptime = %v, want 200", got)
	}
}

func TestAddHeartbeat_SameTimestampAccepted(t *testing.T) {
	s := New(nil)
	id := DeviceID("device-1")
	t0 := time.Date(2024, 1, 1, 12, 0, 0, 0, time.UTC)

	_ = s.AddHeartbeat(id, t0)
	if err := s.AddHeartbeat(id, t0); err != nil {
		t.Fatalf("same timestamp should be accepted: %v", err)
	}
	// span still zero → 1 minute floor; 2 beats → 200
	if got := s.Uptime(id); got != 200 {
		t.Fatalf("uptime = %v, want 200", got)
	}
}

func TestAddHeartbeat_OutOfSequence(t *testing.T) {
	s := New(nil)
	id := DeviceID("device-1")
	t0 := time.Date(2024, 1, 1, 12, 0, 0, 0, time.UTC)
	t1 := t0.Add(time.Minute)

	_ = s.AddHeartbeat(id, t1)
	err := s.AddHeartbeat(id, t0)
	if !errors.Is(err, ErrOutOfSequence) {
		t.Fatalf("err = %v, want ErrOutOfSequence", err)
	}
	// rejected beat must not affect uptime: still 1 beat → 100
	if got := s.Uptime(id); got != 100 {
		t.Fatalf("uptime = %v, want 100", got)
	}
}

func TestUptime_TwoHeartbeatsOverTwoMinutes(t *testing.T) {
	s := New(nil)
	id := DeviceID("device-1")
	t0 := time.Date(2024, 1, 1, 12, 0, 0, 0, time.UTC)

	_ = s.AddHeartbeat(id, t0)
	_ = s.AddHeartbeat(id, t0.Add(2*time.Minute))

	if got := s.Uptime(id); got != 100 {
		t.Fatalf("uptime = %v, want 100", got)
	}
}

func TestUptime_UnknownDevice(t *testing.T) {
	s := New(nil)
	if got := s.Uptime(DeviceID("missing")); got != 0 {
		t.Fatalf("uptime = %v, want 0", got)
	}
}

func TestUptime_IsPerDevice(t *testing.T) {
	s := New(nil)
	a := DeviceID("device-1")
	b := DeviceID("device-2")
	t0 := time.Date(2024, 1, 1, 12, 0, 0, 0, time.UTC)

	_ = s.AddHeartbeat(a, t0)
	_ = s.AddHeartbeat(a, t0.Add(time.Minute))
	_ = s.AddHeartbeat(b, t0)

	if got := s.Uptime(a); got != 200 {
		t.Fatalf("device-1 uptime = %v, want 200", got)
	}
	if got := s.Uptime(b); got != 100 {
		t.Fatalf("device-2 uptime = %v, want 100 (single beat = 1 minute)", got)
	}
}