package strategy

import (
	"github.com/shopspring/decimal"
	"testing"
)

// --- EMA 的表格式驅動測試 (新增) ---

func TestEMA(t *testing.T) {
	d10 := decimal.NewFromInt(10)
	d11 := decimal.NewFromInt(11)
	d12 := decimal.NewFromInt(12)
	d13 := decimal.NewFromInt(13)
	d20 := decimal.NewFromInt(20)
	
	type pushCheck struct {
		wantEMA decimal.Decimal
		wantOK  bool
	}

	testCases := []struct {
		name         string
		n            uint
		inputs       []decimal.Decimal
		pushChecks   []pushCheck
		wantFinalEMA decimal.Decimal
		wantFinalOK  bool
	}{
		{
			name:   "EMA-3 標準計算",
			n:      3, // α = 2 / (3 + 1) = 0.5
			inputs: []decimal.Decimal{d10, d11, d12},
			pushChecks: []pushCheck{
				{d10, true},                         // 第一次, EMA = 10
				{decimal.NewFromFloat(10.5), true},  // 第二次, 0.5*11 + (1-0.5)*10 = 5.5 + 5 = 10.5
				{decimal.NewFromFloat(11.25), true}, // 第三次, 0.5*12 + (1-0.5)*10.5 = 6 + 5.25 = 11.25
			},
			wantFinalEMA: decimal.NewFromFloat(11.25),
			wantFinalOK:  true,
		},
		{
			name:   "EMA-1 邊界情況",
			n:      1, // α = 2 / (1 + 1) = 1
			inputs: []decimal.Decimal{d10, d13, d11},
			pushChecks: []pushCheck{
				{d10, true}, // 第一次, EMA = 10
				{d13, true}, // 第二次, 1*13 + 0*10 = 13
				{d11, true}, // 第三次, 1*11 + 0*13 = 11
			},
			wantFinalEMA: d11,
			wantFinalOK:  true,
		},
		{
			name:   "EMA-0 無效情況",
			n:      0,
			inputs: []decimal.Decimal{d10, d20},
			pushChecks: []pushCheck{
				{decimal.Zero, false},
				{decimal.Zero, false},
			},
			wantFinalEMA: decimal.Zero,
			wantFinalOK:  false,
		},
		{
			name:         "在空實例上呼叫 GetEMA",
			n:            5,
			inputs:       []decimal.Decimal{},
			pushChecks:   []pushCheck{},
			wantFinalEMA: decimal.Zero,
			wantFinalOK:  false,
		},
	}

	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			ema := NewEMA(tc.n)

			for i, input := range tc.inputs {
				gotEMA, gotOK := ema.Push(input)
				if i < len(tc.pushChecks) {
					check := tc.pushChecks[i]
					if gotOK != check.wantOK {
						t.Errorf("Push #%d 的 OK 狀態錯誤: got %v, want %v", i+1, gotOK, check.wantOK)
					}
					// 使用 String() 進行比較，避免浮點數精度問題
					if gotEMA.String() != check.wantEMA.String() {
						t.Errorf("Push #%d 的 EMA 值錯誤: got %s, want %s", i+1, gotEMA.String(), check.wantEMA.String())
					}
				}
			}

			finalEMA, finalOK := ema.GetEMA()
			if finalOK != tc.wantFinalOK {
				t.Errorf("最終 GetEMA 的 OK 狀態錯誤: got %v, want %v", finalOK, tc.wantFinalOK)
			}
			if finalEMA.String() != tc.wantFinalEMA.String() {
				t.Errorf("最終 GetEMA 的 EMA 值錯誤: got %s, want %s", finalEMA.String(), tc.wantFinalEMA.String())
			}
		})
	}
}