package pipelinedb

import (
	"encoding/binary"
	"errors"
	"os"
	"sort"
	"testing"
)

// TestIndexEntry 测试索引条目的基本功能
func TestIndexEntry(t *testing.T) {
	entry1 := IndexEntry{ID: 100, PageNo: 5, SlotNo: 10}
	entry2 := IndexEntry{ID: 200, PageNo: 8, SlotNo: 15}
	entry3 := IndexEntry{ID: 100, PageNo: 6, SlotNo: 12} // 相同ID，不同位置

	// 测试Less方法
	if !entry1.Less(entry2) {
		t.Error("entry1 should be less than entry2")
	}

	if entry2.Less(entry1) {
		t.Error("entry2 should not be less than entry1")
	}

	if entry1.Less(entry3) || entry3.Less(entry1) {
		t.Error("entries with same ID should be equal")
	}
}

// TestNewGroupIndex 测试组索引的创建
func TestNewGroupIndex(t *testing.T) {
	groupName := "test_group"
	idx := NewGroupIndex(groupName)

	if idx == nil {
		t.Fatal("NewGroupIndex returned nil")
	}

	if idx.name != groupName {
		t.Errorf("index name = %s, want %s", idx.name, groupName)
	}

	if idx.Count() != 0 {
		t.Errorf("initial count = %d, want 0", idx.Count())
	}

	if idx.tree == nil {
		t.Error("B+Tree not initialized")
	}
}

// TestTableIndexInsert 测试索引插入操作
func TestTableIndexInsert(t *testing.T) {
	idx := NewGroupIndex("test")

	// 插入一些条目
	testData := []struct {
		id     int64
		pageNo uint16
		slotNo uint16
	}{
		{100, 1, 5},
		{200, 2, 10},
		{150, 1, 8},
		{300, 3, 2},
	}

	for _, data := range testData {
		idx.Insert(data.id, data.pageNo, data.slotNo)
	}

	// 验证索引大小
	if idx.Count() != len(testData) {
		t.Errorf("count after inserts = %d, want %d", idx.Count(), len(testData))
	}

	// 验证每个条目都能找到
	for _, data := range testData {
		pageNo, slotNo, found := idx.Get(data.id)
		if !found {
			t.Errorf("entry with ID %d not found", data.id)
			continue
		}
		if pageNo != data.pageNo || slotNo != data.slotNo {
			t.Errorf("entry %d: got (%d, %d), want (%d, %d)",
				data.id, pageNo, slotNo, data.pageNo, data.slotNo)
		}
	}
}

// TestTableIndexInsertUpdate 测试插入时的更新操作
func TestTableIndexInsertUpdate(t *testing.T) {
	idx := NewGroupIndex("test")

	id := int64(100)

	// 首次插入
	idx.Insert(id, 1, 5)

	pageNo, slotNo, found := idx.Get(id)
	if !found || pageNo != 1 || slotNo != 5 {
		t.Errorf("first insert: got (%d, %d, %t), want (1, 5, true)", pageNo, slotNo, found)
	}

	// 更新同一ID的位置
	idx.Insert(id, 2, 10)

	pageNo, slotNo, found = idx.Get(id)
	if !found || pageNo != 2 || slotNo != 10 {
		t.Errorf("after update: got (%d, %d, %t), want (2, 10, true)", pageNo, slotNo, found)
	}

	// 验证索引大小没有增加
	if idx.Count() != 1 {
		t.Errorf("count after update = %d, want 1", idx.Count())
	}
}

// TestTableIndexGet 测试索引查找操作
func TestTableIndexGet(t *testing.T) {
	idx := NewGroupIndex("test")

	// 插入测试数据
	idx.Insert(100, 1, 5)
	idx.Insert(200, 2, 10)
	idx.Insert(300, 3, 15)

	// 测试存在的条目
	pageNo, slotNo, found := idx.Get(200)
	if !found || pageNo != 2 || slotNo != 10 {
		t.Errorf("Get(200) = (%d, %d, %t), want (2, 10, true)", pageNo, slotNo, found)
	}

	// 测试不存在的条目
	pageNo, slotNo, found = idx.Get(999)
	if found || pageNo != 0 || slotNo != 0 {
		t.Errorf("Get(999) = (%d, %d, %t), want (0, 0, false)", pageNo, slotNo, found)
	}
}

// TestTableIndexDelete 测试索引删除操作
func TestTableIndexDelete(t *testing.T) {
	idx := NewGroupIndex("test")

	// 插入测试数据
	testIDs := []int64{100, 200, 300, 400}
	for i, id := range testIDs {
		idx.Insert(id, uint16(i+1), uint16(i*5))
	}

	initialCount := idx.Count()

	// 删除存在的条目
	deleted := idx.Delete(200)
	if !deleted {
		t.Error("Delete(200) should return true")
	}

	// 验证条目被删除
	_, _, found := idx.Get(200)
	if found {
		t.Error("deleted entry should not be found")
	}

	// 验证索引大小减少
	if idx.Count() != initialCount-1 {
		t.Errorf("count after delete = %d, want %d", idx.Count(), initialCount-1)
	}

	// 删除不存在的条目
	deleted = idx.Delete(999)
	if deleted {
		t.Error("Delete(999) should return false")
	}

	// 验证索引大小没有变化
	if idx.Count() != initialCount-1 {
		t.Errorf("count after deleting non-existent = %d, want %d", idx.Count(), initialCount-1)
	}

	// 验证其他条目仍然存在
	for _, id := range []int64{100, 300, 400} {
		_, _, found := idx.Get(id)
		if !found {
			t.Errorf("entry %d should still exist", id)
		}
	}
}

// TestTableIndexRange 测试范围查询
func TestTableIndexRange(t *testing.T) {
	idx := NewGroupIndex("test")

	// 插入测试数据（乱序插入）
	testData := []struct {
		id     int64
		pageNo uint16
		slotNo uint16
	}{
		{300, 3, 15},
		{100, 1, 5},
		{500, 5, 25},
		{200, 2, 10},
		{400, 4, 20},
	}

	for _, data := range testData {
		idx.Insert(data.id, data.pageNo, data.slotNo)
	}

	// 测试范围查询 [200, 400]
	var results []int64
	idx.Range(200, 400, func(id int64, pageNo, slotNo uint16) bool {
		results = append(results, id)
		return true // 继续遍历
	})

	// 验证结果按ID升序排列
	expectedIDs := []int64{200, 300, 400}
	if len(results) != len(expectedIDs) {
		t.Errorf("range query returned %d results, want %d", len(results), len(expectedIDs))
		t.Errorf("actual results: %v", results)
	}

	for i, expected := range expectedIDs {
		if i >= len(results) || results[i] != expected {
			t.Errorf("result[%d] = %d, want %d", i, results[i], expected)
		}
	}

	// 测试提前终止的范围查询
	results = nil
	count := 0
	idx.Range(100, 500, func(id int64, pageNo, slotNo uint16) bool {
		results = append(results, id)
		count++
		return count < 2 // 只处理前2个
	})

	if len(results) != 2 {
		t.Errorf("early termination returned %d results, want 2", len(results))
	}

	if results[0] != 100 || results[1] != 200 {
		t.Errorf("early termination results = %v, want [100, 200]", results)
	}
}

// TestTableIndexRangeEmpty 测试空范围查询
func TestTableIndexRangeEmpty(t *testing.T) {
	idx := NewGroupIndex("test")

	// 插入一些数据
	idx.Insert(100, 1, 5)
	idx.Insert(300, 3, 15)

	// 查询不存在的范围
	var results []int64
	idx.Range(150, 250, func(id int64, pageNo, slotNo uint16) bool {
		results = append(results, id)
		return true
	})

	if len(results) != 0 {
		t.Errorf("empty range query returned %d results, want 0", len(results))
	}
}

// TestTableIndexClear 测试清空索引
func TestTableIndexClear(t *testing.T) {
	idx := NewGroupIndex("test")

	// 插入一些数据
	for i := int64(1); i <= 10; i++ {
		idx.Insert(i, uint16(i), uint16(i*2))
	}

	// 验证数据存在
	if idx.Count() != 10 {
		t.Errorf("count before clear = %d, want 10", idx.Count())
	}

	// 清空索引
	idx.Clear()

	// 验证索引被清空
	if idx.Count() != 0 {
		t.Errorf("count after clear = %d, want 0", idx.Count())
	}

	// 验证数据不再存在
	_, _, found := idx.Get(5)
	if found {
		t.Error("data should not exist after clear")
	}

	// 验证可以重新插入数据
	idx.Insert(100, 1, 5)
	if idx.Count() != 1 {
		t.Errorf("count after re-insert = %d, want 1", idx.Count())
	}
}

// TestNewIndexManager 测试索引管理器的创建
func TestNewIndexManager(t *testing.T) {
	im := NewIndexManager()

	if im == nil {
		t.Fatal("NewIndexManager returned nil")
	}

	if im.indexes == nil {
		t.Error("indexes map not initialized")
	}

	// 验证初始状态
	stats := im.GetStats()
	if len(stats) != 0 {
		t.Errorf("initial stats length = %d, want 0", len(stats))
	}
}

// TestIndexManagerGetOrCreateIndex 测试获取或创建索引
func TestIndexManagerGetOrCreateIndex(t *testing.T) {
	im := NewIndexManager()

	groupName := "test_group"

	// 第一次调用应该创建新索引
	idx1 := im.GetOrCreateIndex(groupName)
	if idx1 == nil {
		t.Fatal("GetOrCreateIndex returned nil")
	}

	if idx1.name != groupName {
		t.Errorf("index name = %s, want %s", idx1.name, groupName)
	}

	// 第二次调用应该返回相同的索引
	idx2 := im.GetOrCreateIndex(groupName)
	if idx2 != idx1 {
		t.Error("GetOrCreateIndex should return the same index instance")
	}

	// 验证统计信息
	stats := im.GetStats()
	if len(stats) != 1 {
		t.Errorf("stats length = %d, want 1", len(stats))
	}

	if stats[groupName] != 0 {
		t.Errorf("stats[%s] = %d, want 0", groupName, stats[groupName])
	}
}

// TestIndexManagerGetIndex 测试获取索引
func TestIndexManagerGetIndex(t *testing.T) {
	im := NewIndexManager()

	groupName := "test_group"

	// 获取不存在的索引
	idx, exists := im.GetIndex(groupName)
	if exists || idx != nil {
		t.Error("GetIndex should return (nil, false) for non-existent index")
	}

	// 创建索引
	createdIdx := im.GetOrCreateIndex(groupName)

	// 获取存在的索引
	idx, exists = im.GetIndex(groupName)
	if !exists || idx != createdIdx {
		t.Error("GetIndex should return the created index")
	}
}

// TestIndexManagerDropIndex 测试删除索引
func TestIndexManagerDropIndex(t *testing.T) {
	im := NewIndexManager()

	groupName := "test_group"

	// 创建索引并添加数据
	idx := im.GetOrCreateIndex(groupName)
	idx.Insert(100, 1, 5)
	idx.Insert(200, 2, 10)

	// 验证索引存在且有数据
	if idx.Count() != 2 {
		t.Errorf("index count = %d, want 2", idx.Count())
	}

	stats := im.GetStats()
	if stats[groupName] != 2 {
		t.Errorf("stats[%s] = %d, want 2", groupName, stats[groupName])
	}

	// 删除索引
	im.DropIndex(groupName)

	// 验证索引被删除
	_, exists := im.GetIndex(groupName)
	if exists {
		t.Error("index should not exist after drop")
	}

	// 验证统计信息更新
	stats = im.GetStats()
	if len(stats) != 0 {
		t.Errorf("stats length after drop = %d, want 0", len(stats))
	}

	// 删除不存在的索引应该是安全的
	im.DropIndex("non_existent")
}

// TestIndexManagerGetStats 测试获取统计信息
func TestIndexManagerGetStats(t *testing.T) {
	im := NewIndexManager()

	// 创建多个索引并添加不同数量的数据
	groups := map[string]int{
		"group1": 5,
		"group2": 10,
		"group3": 3,
	}

	for groupName, count := range groups {
		idx := im.GetOrCreateIndex(groupName)
		for i := 0; i < count; i++ {
			idx.Insert(int64(i), uint16(i), uint16(i*2))
		}
	}

	// 获取统计信息
	stats := im.GetStats()

	// 验证统计信息
	if len(stats) != len(groups) {
		t.Errorf("stats length = %d, want %d", len(stats), len(groups))
	}

	for groupName, expectedCount := range groups {
		if stats[groupName] != expectedCount {
			t.Errorf("stats[%s] = %d, want %d", groupName, stats[groupName], expectedCount)
		}
	}
}

// MockPipelineDB 用于测试RebuildIndex的模拟数据库
type MockPipelineDB struct {
	pages map[uint16]*MockPage
}

type MockPage struct {
	data       []byte
	nextPageNo uint16
	slots      []uint16
}

func (p *MockPage) slotArray() []uint16 {
	return p.slots
}

func (p *MockPage) nextPage() uint16 {
	return p.nextPageNo
}

func NewMockPipelineDB() *MockPipelineDB {
	return &MockPipelineDB{
		pages: make(map[uint16]*MockPage),
	}
}

func (db *MockPipelineDB) readPage(pageNo uint16) (*MockPage, error) {
	if page, exists := db.pages[pageNo]; exists {
		return page, nil
	}
	return nil, errors.New("page not found")
}

func (db *MockPipelineDB) addPage(pageNo uint16, nextPage uint16, records []struct {
	id     int64
	offset uint16
}) {
	page := &MockPage{
		data:       make([]byte, PageSize),
		nextPageNo: nextPage,
		slots:      make([]uint16, len(records)),
	}

	for i, record := range records {
		// 将ID写入指定偏移位置
		binary.LittleEndian.PutUint64(page.data[record.offset:], uint64(record.id))
		page.slots[i] = record.offset
	}

	db.pages[pageNo] = page
}

// TestRebuildIndex 测试索引重建
func TestRebuildIndex(t *testing.T) {
	// 创建一个临时的PipelineDB实例用于测试
	tmpFile, err := os.CreateTemp("", "rebuild_test_*.db")
	if err != nil {
		t.Fatalf("failed to create temp file: %v", err)
	}
	defer os.Remove(tmpFile.Name())
	tmpFile.Close()

	config := &Config{CacheSize: 10}
	pdb, err := Open(Options{
		Filename: tmpFile.Name(),
		Config:   config,
	})
	if err != nil {
		t.Fatalf("Open failed: %v", err)
	}
	defer pdb.Stop()

	// 先添加一些测试数据
	testData := [][]byte{
		[]byte("test data 1"),
		[]byte("test data 2"),
		[]byte("test data 3"),
	}

	var recordIDs []int64
	for _, data := range testData {
		recordID, err := pdb.AcceptData("test_group", data, `{"test": true}`)
		if err != nil {
			t.Fatalf("AcceptData failed: %v", err)
		}
		recordIDs = append(recordIDs, recordID)
	}

	// 重建索引
	idx, err := pdb.RebuildIndex("test_group", 1)
	if err != nil {
		t.Errorf("RebuildIndex returned error: %v", err)
	}

	if idx == nil {
		t.Fatal("RebuildIndex returned nil index")
	}

	// 验证索引包含所有记录
	if idx.Count() != len(recordIDs) {
		t.Errorf("rebuilt index count = %d, want %d", idx.Count(), len(recordIDs))
	}

	// 验证每个记录都能在索引中找到
	for _, recordID := range recordIDs {
		_, _, found := idx.Get(recordID)
		if !found {
			t.Errorf("record %d not found in rebuilt index", recordID)
		}
	}
}

// TestIndexLargeDataset 测试大数据集的索引操作
func TestIndexLargeDataset(t *testing.T) {
	idx := NewGroupIndex("large_test")

	const numRecords = 10000

	// 插入大量记录
	for i := int64(1); i <= numRecords; i++ {
		idx.Insert(i, uint16(i%1000), uint16(i%100))
	}

	// 验证记录数量
	if idx.Count() != numRecords {
		t.Errorf("count = %d, want %d", idx.Count(), numRecords)
	}

	// 随机验证一些记录
	testIDs := []int64{1, 100, 1000, 5000, 9999, 10000}
	for _, id := range testIDs {
		_, _, found := idx.Get(id)
		if !found {
			t.Errorf("record %d not found", id)
		}
	}

	// 测试范围查询
	var rangeResults []int64
	idx.Range(5000, 5010, func(id int64, pageNo, slotNo uint16) bool {
		rangeResults = append(rangeResults, id)
		return true
	})

	expectedRange := []int64{5000, 5001, 5002, 5003, 5004, 5005, 5006, 5007, 5008, 5009, 5010}
	if len(rangeResults) != len(expectedRange) {
		t.Errorf("range query returned %d results, want %d", len(rangeResults), len(expectedRange))
	}

	// 删除一些记录
	for i := int64(1000); i <= 2000; i++ {
		idx.Delete(i)
	}

	// 验证删除后的数量
	expectedCount := numRecords - 1001 // 删除了1001个记录（1000到2000，包含两端）
	if idx.Count() != expectedCount {
		t.Errorf("count after deletion = %d, want %d", idx.Count(), expectedCount)
	}
}

// TestIndexOrdering 测试索引的有序性
func TestIndexOrdering(t *testing.T) {
	idx := NewGroupIndex("order_test")

	// 乱序插入数据
	ids := []int64{500, 100, 300, 200, 400, 600, 150, 350}
	for _, id := range ids {
		idx.Insert(id, uint16(id/100), uint16(id%100))
	}

	// 范围查询应该返回有序结果
	var results []int64
	idx.Range(0, 1000, func(id int64, pageNo, slotNo uint16) bool {
		results = append(results, id)
		return true
	})

	// 验证结果是有序的
	if !sort.SliceIsSorted(results, func(i, j int) bool {
		return results[i] < results[j]
	}) {
		t.Errorf("range query results are not sorted: %v", results)
	}

	// 验证所有ID都存在
	sort.Slice(ids, func(i, j int) bool { return ids[i] < ids[j] })
	if len(results) != len(ids) {
		t.Errorf("result count = %d, want %d", len(results), len(ids))
	}

	for i, expected := range ids {
		if i >= len(results) || results[i] != expected {
			t.Errorf("result[%d] = %d, want %d", i, results[i], expected)
		}
	}
}

// BenchmarkTableIndexInsert 性能测试：索引插入
func BenchmarkTableIndexInsert(b *testing.B) {
	idx := NewGroupIndex("bench_test")

	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		idx.Insert(int64(i), uint16(i%1000), uint16(i%100))
	}
}

// BenchmarkTableIndexGet 性能测试：索引查找
func BenchmarkTableIndexGet(b *testing.B) {
	idx := NewGroupIndex("bench_test")

	// 预填充数据
	for i := 0; i < 100000; i++ {
		idx.Insert(int64(i), uint16(i%1000), uint16(i%100))
	}

	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		idx.Get(int64(i % 100000))
	}
}

// BenchmarkTableIndexRange 性能测试：范围查询
func BenchmarkTableIndexRange(b *testing.B) {
	idx := NewGroupIndex("bench_test")

	// 预填充数据
	for i := 0; i < 100000; i++ {
		idx.Insert(int64(i), uint16(i%1000), uint16(i%100))
	}

	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		start := int64(i % 90000)
		end := start + 100
		idx.Range(start, end, func(id int64, pageNo, slotNo uint16) bool {
			return true
		})
	}
}

// BenchmarkIndexManagerOperations 性能测试：索引管理器操作
func BenchmarkIndexManagerOperations(b *testing.B) {
	im := NewIndexManager()

	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		groupName := "group_" + string(rune('A'+i%26))
		idx := im.GetOrCreateIndex(groupName)
		idx.Insert(int64(i), uint16(i%1000), uint16(i%100))

		if i%1000 == 0 {
			im.GetStats()
		}
	}
}