package strategy

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

// --- 表格式驅動測試 (Table-Driven Test) ---

func TestRingQD(t *testing.T) {
	// 為了方便測試，預先建立幾個 decimal 數值
	d10 := decimal.NewFromInt(10)
	d20 := decimal.NewFromInt(20)
	d30 := decimal.NewFromInt(30)
	d40 := decimal.NewFromInt(40)
	d50 := decimal.NewFromInt(50)
	d_neg5 := decimal.NewFromInt(-5)

	// 定義測試案例的結構
	testCases := []struct {
		name       string            // 測試案例的名稱
		n          int               // ringQD 的大小
		inputs     []decimal.Decimal // 輸入的數值序列
		wantSum    decimal.Decimal   // 預期的總和
		wantMean   decimal.Decimal   // 預期的平均值
		wantValues []decimal.Decimal // 預期隊列中最後的值
		wantReady  bool              // 預期的就緒狀態
	}{
		{
			name:       "未滿載的情況",
			n:          5,
			inputs:     []decimal.Decimal{d10, d20},
			wantSum:    decimal.NewFromInt(30),
			wantMean:   decimal.NewFromInt(15),
			wantValues: []decimal.Decimal{d10, d20},
			wantReady:  false,
		},
		{
			name:       "剛好滿載的情況",
			n:          3,
			inputs:     []decimal.Decimal{d10, d20, d30},
			wantSum:    decimal.NewFromInt(60),
			wantMean:   decimal.NewFromInt(20),
			wantValues: []decimal.Decimal{d10, d20, d30},
			wantReady:  true,
		},
		{
			name:       "超出容量，舊資料被移除",
			n:          3,
			inputs:     []decimal.Decimal{d10, d20, d30, d40, d50},
			wantSum:    decimal.NewFromInt(120), // 30 + 40 + 50
			wantMean:   decimal.NewFromInt(40),
			wantValues: []decimal.Decimal{d30, d40, d50},
			wantReady:  true,
		},
		{
			name:       "包含零與負數",
			n:          4,
			inputs:     []decimal.Decimal{d10, d_neg5, decimal.Zero, d30, d_neg5},
			wantSum:    decimal.NewFromInt(20), // -5 + 0 + 30 + (-5)
			wantMean:   decimal.NewFromInt(5),
			wantValues: []decimal.Decimal{d_neg5, decimal.Zero, d30, d_neg5},
			wantReady:  true,
		},
		{
			name:       "初始為空",
			n:          5,
			inputs:     []decimal.Decimal{},
			wantSum:    decimal.Zero,
			wantMean:   decimal.Zero,
			wantValues: []decimal.Decimal{},
			wantReady:  false,
		},
		{
			name:       "N 為 1 的邊界情況",
			n:          1,
			inputs:     []decimal.Decimal{d10, d20, d30},
			wantSum:    d30,
			wantMean:   d30,
			wantValues: []decimal.Decimal{d30},
			wantReady:  true,
		},
		{
			name:       "N 為 0 的無效情況",
			n:          0,
			inputs:     []decimal.Decimal{d10, d20, d30},
			wantSum:    decimal.Zero,
			wantMean:   decimal.Zero,
			wantValues: []decimal.Decimal{},
			wantReady:  true,
		},
	}

	// 遍歷所有測試案例
	for _, tc := range testCases {
		t.Run(tc.name, func(t *testing.T) {
			// 針對每個案例建立一個新的 ringQD
			q := newRingQD(tc.n)

			// 依序推入資料
			for _, val := range tc.inputs {
				q.push(val)
			}

			// 驗證總和
			if !q.sum.Equals(tc.wantSum) {
				t.Errorf("Sum 錯誤：got %v, want %v", q.sum, tc.wantSum)
			}

			// 驗證平均值
			gotMean := q.mean()
			if !gotMean.Equals(tc.wantMean) {
				t.Errorf("Mean 錯誤：got %v, want %v", gotMean, tc.wantMean)
			}

			// 驗證就緒狀態
			if q.ready() != tc.wantReady {
				t.Errorf("Ready 狀態錯誤：got %v, want %v", q.ready(), tc.wantReady)
			}

			// 驗證隊列中的值
			gotValues := q.values()
			if !reflect.DeepEqual(gotValues, tc.wantValues) {
				t.Errorf("Values 錯誤：got %v, want %v", gotValues, tc.wantValues)
			}
		})
	}
}