package services

import (
	"testing"
)

func TestCalcPercentChange(t *testing.T) {
	tests := []struct {
		name     string
		previous int64
		current  int64
		expected float64
	}{
		{"zero to positive", 0, 100, 100.0},
		{"zero to zero", 0, 0, 0.0},
		{"positive to zero", 100, 0, -100.0},
		{"same value", 100, 100, 0.0},
		{"50% increase", 100, 150, 50.0},
		{"50% decrease", 200, 100, -50.0},
		{"double", 50, 100, 100.0},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := calcPercentChange(tt.previous, tt.current)
			if result != tt.expected {
				t.Errorf("calcPercentChange(%d, %d) = %f, want %f", tt.previous, tt.current, result, tt.expected)
			}
		})
	}
}

func TestCalcFloatPercentChange(t *testing.T) {
	tests := []struct {
		name     string
		previous float64
		current  float64
		expected float64
	}{
		{"zero to positive", 0.0, 50.0, 100.0},
		{"zero to zero", 0.0, 0.0, 0.0},
		{"50% increase", 80.0, 120.0, 50.0},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := calcFloatPercentChange(tt.previous, tt.current)
			if result != tt.expected {
				t.Errorf("calcFloatPercentChange(%f, %f) = %f, want %f", tt.previous, tt.current, result, tt.expected)
			}
		})
	}
}

func TestNewAdvancedAnalyticsService(t *testing.T) {
	// Test nil logger fallback
	svc := NewAdvancedAnalyticsService(nil, nil)
	if svc == nil {
		t.Fatal("expected non-nil service")
	}
	if svc.logger == nil {
		t.Fatal("expected non-nil logger (nop logger)")
	}
}