package service

import (
	"database/sql"
	"testing"
	"time"

	"github.com/daniil/homelab-api/internal/model"
)

func TestCalculateInterestForDeposit_NotDeposit(t *testing.T) {
	s := &InterestService{}
	deposit := &model.SavingsCategory{IsDeposit: false}
	result, err := s.CalculateInterestForDeposit(deposit)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if result != "" {
		t.Errorf("expected empty result for non-deposit, got %q", result)
	}
}

func TestCalculateInterestForDeposit_ZeroRate(t *testing.T) {
	s := &InterestService{}
	deposit := &model.SavingsCategory{IsDeposit: true, InterestRate: 0}
	result, err := s.CalculateInterestForDeposit(deposit)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if result != "" {
		t.Errorf("expected empty result for zero rate, got %q", result)
	}
}

func TestCalculateInterestForDeposit_NoStartDate(t *testing.T) {
	s := &InterestService{}
	deposit := &model.SavingsCategory{
		IsDeposit:    true,
		InterestRate: 10,
		DepositStartDate: sql.NullTime{Valid: false},
	}
	_, err := s.CalculateInterestForDeposit(deposit)
	if err == nil {
		t.Error("expected error for missing start date")
	}
}

func TestCalculateInterestForDeposit_ExpiredDeposit(t *testing.T) {
	s := &InterestService{}
	deposit := &model.SavingsCategory{
		IsDeposit:    true,
		InterestRate: 10,
		DepositTerm:  3, // 3 months
		DepositStartDate: sql.NullTime{
			Time:  time.Now().AddDate(0, -6, 0), // 6 months ago
			Valid: true,
		},
	}
	result, err := s.CalculateInterestForDeposit(deposit)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if result != "" {
		t.Errorf("expected empty result for expired deposit, got %q", result)
	}
}

func TestCalculateInterestForDeposit_WrongDay(t *testing.T) {
	s := &InterestService{}
	// Start date with day that is NOT today
	// We pick a day that will never be today unless very lucky
	today := time.Now()
	// Pick a start day that differs from today
	startDay := today.Day() + 1
	if startDay > 28 {
		startDay = 1
	}
	startDate := time.Date(today.Year()-1, today.Month(), startDay, 0, 0, 0, 0, time.UTC)
	
	deposit := &model.SavingsCategory{
		Name:         "Test",
		IsDeposit:    true,
		InterestRate: 12,
		DepositStartDate: sql.NullTime{
			Time:  startDate,
			Valid: true,
		},
	}
	// Should return empty string (not today's interest day) — no DB call
	result, err := s.CalculateInterestForDeposit(deposit)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if result != "" {
		t.Errorf("expected empty result for non-interest day, got %q", result)
	}
}