package strategy

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

// --- SMA 的表格式驅動測試 ---

func TestSMA(t *testing.T) {
	d10 := decimal.NewFromInt(10)
	d20 := decimal.NewFromInt(20)
	d30 := decimal.NewFromInt(30)
	d40 := decimal.NewFromInt(40)
	d50 := decimal.NewFromInt(50)

	// 定義 Push 過程中的檢查點結構
	type pushCheck struct {
		wantSMA decimal.Decimal
		wantOK  bool
	}

	testCases := []struct {
		name         string
		n            uint
		inputs       []decimal.Decimal
		pushChecks   []pushCheck     // 驗證每一次 Push 的回傳值
		wantFinalSMA decimal.Decimal // 驗證最後 GetSMA 的回傳值
		wantFinalOK  bool
	}{
		{
			name:   "SMA-5 未滿載",
			n:      5,
			inputs: []decimal.Decimal{d10, d20, d30},
			pushChecks: []pushCheck{
				{decimal.Zero, false},
				{decimal.Zero, false},
				{decimal.Zero, false},
			},
			wantFinalSMA: decimal.Zero,
			wantFinalOK:  false,
		},
		{
			name:   "SMA-3 剛好滿載",
			n:      3,
			inputs: []decimal.Decimal{d10, d20, d30},
			pushChecks: []pushCheck{
				{decimal.Zero, false},
				{decimal.Zero, false},
				{decimal.NewFromInt(20), true}, // (10+20+30)/3
			},
			wantFinalSMA: decimal.NewFromInt(20),
			wantFinalOK:  true,
		},
		{
			name:   "SMA-3 滾動計算",
			n:      3,
			inputs: []decimal.Decimal{d10, d20, d30, d40, d50},
			pushChecks: []pushCheck{
				{decimal.Zero, false},
				{decimal.Zero, false},
				{decimal.NewFromInt(20), true}, // (10+20+30)/3
				{decimal.NewFromInt(30), true}, // (20+30+40)/3
				{decimal.NewFromInt(40), true}, // (30+40+50)/3
			},
			wantFinalSMA: decimal.NewFromInt(40),
			wantFinalOK:  true,
		},
		{
			name:   "SMA-1 邊界情況",
			n:      1,
			inputs: []decimal.Decimal{d10, d20, d30},
			pushChecks: []pushCheck{
				{d10, true},
				{d20, true},
				{d30, true},
			},
			wantFinalSMA: d30,
			wantFinalOK:  true,
		},
		{
			name:   "SMA-0 無效情況",
			n:      0,
			inputs: []decimal.Decimal{d10, d20, d30},
			pushChecks: []pushCheck{
				{decimal.Zero, false},
				{decimal.Zero, false},
				{decimal.Zero, false},
			},
			wantFinalSMA: decimal.Zero,
			wantFinalOK:  false,
		},
		{
			name:         "在空實例上呼叫 GetSMA",
			n:            5,
			inputs:       []decimal.Decimal{},
			pushChecks:   []pushCheck{},
			wantFinalSMA: decimal.Zero,
			wantFinalOK:  false,
		},
	}

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

			// 驗證每一次 Push 的結果
			for i, input := range tc.inputs {
				gotSMA, gotOK := sma.Push(input)
				// 確保 pushChecks 陣列不會索引越界
				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)
					}
					if !gotSMA.Equals(check.wantSMA) {
						t.Errorf("Push #%d 的 SMA 值錯誤: got %s, want %s", i+1, gotSMA.String(), check.wantSMA.String())
					}
				}
			}

			// 在所有 Push 操作完成後，驗證最終 GetSMA 的結果
			finalSMA, finalOK := sma.GetSMA()
			if finalOK != tc.wantFinalOK {
				t.Errorf("最終 GetSMA 的 OK 狀態錯誤: got %v, want %v", finalOK, tc.wantFinalOK)
			}
			if !finalSMA.Equals(tc.wantFinalSMA) {
				t.Errorf("最終 GetSMA 的 SMA 值錯誤: got %s, want %s", finalSMA.String(), tc.wantFinalSMA.String())
			}
		})
	}
}