package engine

import (
	"testing"

	"git.kingecg.top/kingecg/gomog/pkg/types"
)

// TestProjectionElemMatch 测试 $elemMatch 投影操作符
func TestProjectionElemMatch(t *testing.T) {
	tests := []struct {
		name     string
		data     map[string]interface{}
		field    string
		spec     map[string]interface{}
		expected interface{}
	}{
		{
			name: "elemMatch finds first matching element",
			data: map[string]interface{}{
				"scores": []interface{}{
					map[string]interface{}{"subject": "math", "score": 85},
					map[string]interface{}{"subject": "english", "score": 92},
					map[string]interface{}{"subject": "science", "score": 78},
				},
			},
			field: "scores",
			spec: map[string]interface{}{
				"$elemMatch": map[string]interface{}{
					"score": map[string]interface{}{"$gte": float64(90)},
				},
			},
			expected: map[string]interface{}{"subject": "english", "score": float64(92)},
		},
		{
			name: "elemMatch with no match returns nil",
			data: map[string]interface{}{
				"scores": []interface{}{
					map[string]interface{}{"subject": "math", "score": 65},
					map[string]interface{}{"subject": "english", "score": 72},
				},
			},
			field: "scores",
			spec: map[string]interface{}{
				"$elemMatch": map[string]interface{}{
					"score": map[string]interface{}{"$gte": float64(90)},
				},
			},
			expected: nil,
		},
		{
			name: "elemMatch with non-array field",
			data: map[string]interface{}{
				"name": "Alice",
			},
			field:    "name",
			spec:     map[string]interface{}{"$elemMatch": map[string]interface{}{}},
			expected: nil,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := projectElemMatch(tt.data, tt.field, tt.spec)
			if !compareEq(result, tt.expected) {
				t.Errorf("projectElemMatch() = %v, want %v", result, tt.expected)
			}
		})
	}
}

// TestProjectionSlice 测试 $slice 投影操作符
func TestProjectionSlice(t *testing.T) {
	tests := []struct {
		name      string
		data      map[string]interface{}
		field     string
		sliceSpec interface{}
		expected  interface{}
	}{
		{
			name: "slice with positive limit - first N elements",
			data: map[string]interface{}{
				"tags": []interface{}{"a", "b", "c", "d", "e"},
			},
			field:     "tags",
			sliceSpec: float64(3),
			expected:  []interface{}{"a", "b", "c"},
		},
		{
			name: "slice with negative limit - last N elements",
			data: map[string]interface{}{
				"tags": []interface{}{"a", "b", "c", "d", "e"},
			},
			field:     "tags",
			sliceSpec: float64(-2),
			expected:  []interface{}{"d", "e"},
		},
		{
			name: "slice with skip and limit",
			data: map[string]interface{}{
				"items": []interface{}{1, 2, 3, 4, 5, 6, 7, 8, 9, 10},
			},
			field:     "items",
			sliceSpec: []interface{}{float64(5), float64(3)},
			expected:  []interface{}{float64(6), float64(7), float64(8)},
		},
		{
			name: "slice with skip beyond array length",
			data: map[string]interface{}{
				"items": []interface{}{1, 2, 3},
			},
			field:     "items",
			sliceSpec: []interface{}{float64(10), float64(2)},
			expected:  []interface{}{},
		},
		{
			name: "slice with zero limit",
			data: map[string]interface{}{
				"items": []interface{}{1, 2, 3},
			},
			field:     "items",
			sliceSpec: float64(0),
			expected:  []interface{}{},
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := projectSlice(tt.data, tt.field, tt.sliceSpec)
			if !compareEq(result, tt.expected) {
				t.Errorf("projectSlice() = %v, want %v", result, tt.expected)
			}
		})
	}
}

// TestApplyProjection 测试投影应用
func TestApplyProjection(t *testing.T) {
	tests := []struct {
		name       string
		docs       []types.Document
		projection types.Projection
		expected   int // expected number of documents
	}{
		{
			name: "projection with inclusion mode",
			docs: []types.Document{
				{ID: "1", Data: map[string]interface{}{"name": "Alice", "age": 25, "email": "alice@example.com"}},
				{ID: "2", Data: map[string]interface{}{"name": "Bob", "age": 30, "email": "bob@example.com"}},
			},
			projection: types.Projection{
				"name": 1,
				"age":  1,
			},
			expected: 2,
		},
		{
			name: "projection with exclusion mode",
			docs: []types.Document{
				{ID: "1", Data: map[string]interface{}{"name": "Alice", "age": 25, "email": "alice@example.com"}},
			},
			projection: types.Projection{
				"email": 0,
			},
			expected: 1,
		},
		{
			name: "projection excluding _id",
			docs: []types.Document{
				{ID: "1", Data: map[string]interface{}{"name": "Alice", "age": 25}},
			},
			projection: types.Projection{
				"name": 1,
				"_id":  0,
			},
			expected: 1,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := applyProjection(tt.docs, tt.projection)
			if len(result) != tt.expected {
				t.Errorf("applyProjection() returned %d documents, want %d", len(result), tt.expected)
			}
		})
	}
}

// TestApplyProjectionToDoc 测试单个文档投影
func TestApplyProjectionToDoc(t *testing.T) {
	tests := []struct {
		name       string
		data       map[string]interface{}
		projection types.Projection
		checkField string
		expectHas  bool
	}{
		{
			name: "include specific fields",
			data: map[string]interface{}{
				"name":  "Alice",
				"age":   25,
				"email": "alice@example.com",
			},
			projection: types.Projection{
				"name": 1,
				"age":  1,
			},
			checkField: "name",
			expectHas:  true,
		},
		{
			name: "exclude specific fields",
			data: map[string]interface{}{
				"name":  "Alice",
				"age":   25,
				"email": "alice@example.com",
			},
			projection: types.Projection{
				"email": 0,
			},
			checkField: "email",
			expectHas:  false,
		},
	}

	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			result := applyProjectionToDoc(tt.data, tt.projection)
			_, has := result[tt.checkField]
			if has != tt.expectHas {
				t.Errorf("applyProjectionToDoc() has field %s = %v, want %v", tt.checkField, has, tt.expectHas)
			}
		})
	}
}