//                           _       _
// __      _____  __ ___   ___  __ _| |_ ___
// \ \ /\ / / _ \/ _` \ \ / / |/ _` | __/ _ \
//  \ V  V /  __/ (_| |\ V /| | (_| | ||  __/
//   \_/\_/ \___|\__,_| \_/ |_|\__,_|\__\___|
//
//  Copyright © 2016 - 2024 Weaviate B.V. All rights reserved.
//
//  CONTACT: hello@weaviate.io
//

package inverted

import (
	"math"
	"math/rand"
	"sort"
	"testing"
)

// func BenchmarkAnd10k1m_Old(b *testing.B) {
// 	b.StopTimer()

// 	list1 := propValuePair{
// 		docIDs: docPointers{
// 			docIDs:   randomIDs(1e4),
// 			checksum: []byte{0x01},
// 		},
// 		operator: filters.OperatorEqual,
// 	}

// 	list2 := propValuePair{
// 		docIDs: docPointers{
// 			docIDs:   randomIDs(1e6),
// 			checksum: []byte{0x02},
// 		},
// 		operator: filters.OperatorEqual,
// 	}

// 	b.StartTimer()
// 	for i := 0; i < b.N; i++ {
// 		mergeAnd([]*propValuePair{&list1, &list2}, false)
// 	}
// }

// func BenchmarkAnd10k1m_Optimized(b *testing.B) {
// 	b.StopTimer()

// 	list1 := propValuePair{
// 		docIDs: docPointers{
// 			docIDs:   randomIDs(1e4),
// 			checksum: []byte{0x01},
// 		},
// 		operator: filters.OperatorEqual,
// 	}

// 	list2 := propValuePair{
// 		docIDs: docPointers{
// 			docIDs:   randomIDs(1e6),
// 			checksum: []byte{0x02},
// 		},
// 		operator: filters.OperatorEqual,
// 	}

// 	b.StartTimer()
// 	for i := 0; i < b.N; i++ {
// 		mergeAndOptimized([]*propValuePair{&list1, &list2}, false)
// 	}
// }

// func BenchmarkMultipleListsOf20k_Old(b *testing.B) {
// 	b.StopTimer()

// 	lists := make([]*propValuePair, 10)
// 	for i := range lists {
// 		lists[i] = &propValuePair{
// 			docIDs: docPointers{
// 				docIDs:   randomIDs(2e4),
// 				checksum: []byte{uint8(i)},
// 			},
// 			operator: filters.OperatorEqual,
// 		}
// 	}

// 	b.StartTimer()
// 	for i := 0; i < b.N; i++ {
// 		mergeAnd(lists, false)
// 	}
// }

// func BenchmarkMultipleListsOf20k_Optimized(b *testing.B) {
// 	b.StopTimer()

// 	lists := make([]*propValuePair, 10)
// 	for i := range lists {
// 		lists[i] = &propValuePair{
// 			docIDs: docPointers{
// 				docIDs:   randomIDs(2e4),
// 				checksum: []byte{uint8(i)},
// 			},
// 			operator: filters.OperatorEqual,
// 		}
// 	}

// 	b.StartTimer()
// 	for i := 0; i < b.N; i++ {
// 		mergeAndOptimized(lists, false)
// 	}
// }

func BenchmarkSort10k(b *testing.B) {
	for i := 0; i < b.N; i++ {
		b.StopTimer()
		list := randomIDs(1e4)
		b.StartTimer()

		sort.Slice(list, func(a, b int) bool {
			return list[a] < list[b]
		})
	}
}

func BenchmarkUnsortedLinearSearch(b *testing.B) {
	searchTargets := randomIDs(1e5)

	for i := 0; i < b.N; i++ {
		b.StopTimer()
		list := randomIDs(1e5)
		b.StartTimer()

		for i := range searchTargets {
			linearSearchUnsorted(list, searchTargets[i])
		}
	}
}

func BenchmarkSortedBinarySearch(b *testing.B) {
	searchTargets := randomIDs(1e6)

	for i := 0; i < b.N; i++ {
		b.StopTimer()
		list := randomIDs(1e4)
		b.StartTimer()

		sort.Slice(list, func(a, b int) bool {
			return list[a] < list[b]
		})

		for i := range searchTargets {
			binarySearch(list, searchTargets[i])
		}
	}
}

func BenchmarkHashmap(b *testing.B) {
	searchTargets := randomIDs(1e6)

	for i := 0; i < b.N; i++ {
		b.StopTimer()
		list := randomIDs(1e4)
		b.StartTimer()

		lookup := make(map[uint64]struct{}, len(list))
		for i := range list {
			lookup[list[i]] = struct{}{}
		}

		for i := range searchTargets {
			_, ok := lookup[searchTargets[i]]
			_ = ok
		}
	}
}

func randomIDs(count int) []uint64 {
	out := make([]uint64, count)
	for i := range out {
		out[i] = rand.Uint64()
	}

	return out
}

func linearSearchUnsorted(in []uint64, needle uint64) bool {
	for i := range in {
		if in[i] == needle {
			return true
		}
	}

	return false
}

// function binary_search(A, n, T) is
//     L := 0
//     R := n − 1
//     while L ≤ R do
//         m := floor((L + R) / 2)
//         if A[m] < T then
//             L := m + 1
//         else if A[m] > T then
//             R := m − 1
//         else:
//             return m
//     return unsuccessful

func binarySearch(in []uint64, needle uint64) bool {
	left := 0
	right := len(in) - 1

	for left <= right {
		m := int(math.Floor(float64((left + right)) / float64(2)))
		if in[m] < needle {
			left = m + 1
		} else if in[m] > needle {
			right = m - 1
		} else {
			return true
		}
	}

	return false
}