package strategy

import (
	"context"
	"testing"

	"stock-analysis/internal/backtest"
)

func TestDoubleLow_Name(t *testing.T) {
	s := NewDoubleLow(DoubleLowParams{TopN: 10, Rebalance: 21, MinPrice: 90, MaxPrice: 130, MaxPremium: 30})
	name := s.Name()
	if name == "" {
		t.Error("strategy name should not be empty")
	}
}

func TestDoubleLow_SelectByDoubleLowValue(t *testing.T) {
	s := NewDoubleLow(DoubleLowParams{TopN: 3, Rebalance: 5, MinPrice: 90, MaxPrice: 130, MaxPremium: 30})

	universe := []backtest.Quote{
		{Code: "A", Price: 100, PremiumRate: 10}, // 双低 = 110
		{Code: "B", Price: 95, PremiumRate: 5},   // 双低 = 100 (最低)
		{Code: "C", Price: 110, PremiumRate: 20}, // 双低 = 130
		{Code: "D", Price: 105, PremiumRate: 8},  // 双低 = 113
		{Code: "E", Price: 120, PremiumRate: 15}, // 双低 = 135
	}

	targets, err := s.OnBar(context.Background(), "2020-01-02", universe, nil)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if len(targets) != 3 {
		t.Fatalf("expected 3 targets, got %d", len(targets))
	}

	// 按双低值排序：B(100), A(110), D(113)
	codes := make(map[string]bool)
	for _, tg := range targets {
		codes[tg.Code] = true
	}
	if !codes["B"] || !codes["A"] || !codes["D"] {
		t.Errorf("expected codes B, A, D, got %v", codes)
	}
}

func TestDoubleLow_FilterByPriceRange(t *testing.T) {
	s := NewDoubleLow(DoubleLowParams{TopN: 5, Rebalance: 5, MinPrice: 90, MaxPrice: 130, MaxPremium: 30})

	universe := []backtest.Quote{
		{Code: "A", Price: 85, PremiumRate: 5},  // 价格过低，过滤
		{Code: "B", Price: 100, PremiumRate: 10}, // 合格
		{Code: "C", Price: 135, PremiumRate: 5},  // 价格过高，过滤
	}

	targets, err := s.OnBar(context.Background(), "2020-01-02", universe, nil)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if len(targets) != 1 {
		t.Fatalf("expected 1 target, got %d", len(targets))
	}
	if targets[0].Code != "B" {
		t.Errorf("expected code B, got %s", targets[0].Code)
	}
}

func TestDoubleLow_FilterByPremiumRate(t *testing.T) {
	s := NewDoubleLow(DoubleLowParams{TopN: 5, Rebalance: 5, MinPrice: 90, MaxPrice: 130, MaxPremium: 20})

	universe := []backtest.Quote{
		{Code: "A", Price: 100, PremiumRate: 15}, // 合格
		{Code: "B", Price: 100, PremiumRate: 25}, // 溢价过高，过滤
		{Code: "C", Price: 100, PremiumRate: 0},  // 溢价为0，过滤
		{Code: "D", Price: 100, PremiumRate: -5}, // 负溢价，过滤
	}

	targets, err := s.OnBar(context.Background(), "2020-01-02", universe, nil)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if len(targets) != 1 {
		t.Fatalf("expected 1 target, got %d", len(targets))
	}
	if targets[0].Code != "A" {
		t.Errorf("expected code A, got %s", targets[0].Code)
	}
}

func TestDoubleLow_NoQualifiedCandidates(t *testing.T) {
	s := NewDoubleLow(DoubleLowParams{TopN: 3, Rebalance: 5, MinPrice: 90, MaxPrice: 130, MaxPremium: 30})

	universe := []backtest.Quote{
		{Code: "A", Price: 50, PremiumRate: 5},
		{Code: "B", Price: 200, PremiumRate: 10},
	}

	targets, err := s.OnBar(context.Background(), "2020-01-02", universe, nil)
	if err != nil {
		t.Fatalf("unexpected error: %v", err)
	}
	if targets != nil {
		t.Error("expected nil targets when no qualified candidates")
	}
}

func TestDoubleLow_RebalanceCycle(t *testing.T) {
	s := NewDoubleLow(DoubleLowParams{TopN: 3, Rebalance: 3, MinPrice: 90, MaxPrice: 130, MaxPremium: 30})

	universe := []backtest.Quote{
		{Code: "A", Price: 100, PremiumRate: 10},
	}

	// 第 1 天：调仓
	targets, _ := s.OnBar(context.Background(), "2020-01-02", universe, nil)
	if targets == nil {
		t.Error("day 1 should rebalance")
	}

	// 第 2-3 天：不调仓
	for i := 0; i < 2; i++ {
		targets, _ = s.OnBar(context.Background(), "2020-01-02", universe, nil)
		if targets != nil {
			t.Errorf("day %d should not rebalance", i+2)
		}
	}

	// 第 4 天：调仓
	targets, _ = s.OnBar(context.Background(), "2020-01-02", universe, nil)
	if targets == nil {
		t.Error("day 4 should rebalance")
	}
}

func TestDefaultDoubleLowParams(t *testing.T) {
	p := DefaultDoubleLowParams()
	if p.TopN != 10 {
		t.Errorf("TopN: expected 10, got %d", p.TopN)
	}
	if p.Rebalance != 21 {
		t.Errorf("Rebalance: expected 21, got %d", p.Rebalance)
	}
	if p.MinPrice != 90 {
		t.Errorf("MinPrice: expected 90, got %f", p.MinPrice)
	}
	if p.MaxPrice != 130 {
		t.Errorf("MaxPrice: expected 130, got %f", p.MaxPrice)
	}
	if p.MaxPremium != 30 {
		t.Errorf("MaxPremium: expected 30, got %f", p.MaxPremium)
	}
}