// Copyright (C) 2014 The Syncthing Authors.
//
// This Source Code Form is subject to the terms of the Mozilla Public
// License, v. 2.0. If a copy of the MPL was not distributed with this file,
// You can obtain one at https://mozilla.org/MPL/2.0/.

package scanner

import (
	"bytes"
	"context"
	"crypto/sha256"
	"fmt"
	mrand "math/rand"
	"testing"
)

var blocksTestData = []struct {
	data      []byte
	blocksize int
	hash      []string
}{
	{
		[]byte(""), 1024,
		[]string{
			"e3b0c44298fc1c149afbf4c8996fb92427ae41e4649b934ca495991b7852b855",
		},
	},
	{
		[]byte("contents"), 1024,
		[]string{
			"d1b2a59fbea7e20077af9f91b27e95e865061b270be03ff539ab3b73587882e8",
		},
	},
	{
		[]byte("contents"), 9,
		[]string{
			"d1b2a59fbea7e20077af9f91b27e95e865061b270be03ff539ab3b73587882e8",
		},
	},
	{
		[]byte("contents"), 8,
		[]string{
			"d1b2a59fbea7e20077af9f91b27e95e865061b270be03ff539ab3b73587882e8",
		},
	},
	{
		[]byte("contents"), 7,
		[]string{
			"ed7002b439e9ac845f22357d822bac1444730fbdb6016d3ec9432297b9ec9f73",
			"043a718774c572bd8a25adbeb1bfcd5c0256ae11cecf9f9c3f925d0e52beaf89",
		},
	},
	{
		[]byte("contents"), 3,
		[]string{
			"1143da2bc54c495c4be31d3868785d39ffdfd56df5668f0645d8f14d47647952",
			"e4432baa90819aaef51d2a7f8e148bf7e679610f3173752fabb4dcb2d0f418d3",
			"44ad63f60af0f6db6fdde6d5186ef78176367df261fa06be3079b6c80c8adba4",
		},
	},
	{
		[]byte("conconts"), 3,
		[]string{
			"1143da2bc54c495c4be31d3868785d39ffdfd56df5668f0645d8f14d47647952",
			"1143da2bc54c495c4be31d3868785d39ffdfd56df5668f0645d8f14d47647952",
			"44ad63f60af0f6db6fdde6d5186ef78176367df261fa06be3079b6c80c8adba4",
		},
	},
	{
		[]byte("contenten"), 3,
		[]string{
			"1143da2bc54c495c4be31d3868785d39ffdfd56df5668f0645d8f14d47647952",
			"e4432baa90819aaef51d2a7f8e148bf7e679610f3173752fabb4dcb2d0f418d3",
			"e4432baa90819aaef51d2a7f8e148bf7e679610f3173752fabb4dcb2d0f418d3",
		},
	},
}

func TestBlocks(t *testing.T) {
	for testNo, test := range blocksTestData {
		buf := bytes.NewBuffer(test.data)
		blocks, err := Blocks(context.TODO(), buf, test.blocksize, -1, nil)
		if err != nil {
			t.Fatal(err)
		}

		if l := len(blocks); l != len(test.hash) {
			t.Fatalf("%d: Incorrect number of blocks %d != %d", testNo, l, len(test.hash))
		} else {
			i := 0
			for off := int64(0); off < int64(len(test.data)); off += int64(test.blocksize) {
				if blocks[i].Offset != off {
					t.Errorf("%d/%d: Incorrect offset %d != %d", testNo, i, blocks[i].Offset, off)
				}

				bs := test.blocksize
				if rem := len(test.data) - int(off); bs > rem {
					bs = rem
				}
				if int(blocks[i].Size) != bs {
					t.Errorf("%d/%d: Incorrect length %d != %d", testNo, i, blocks[i].Size, bs)
				}
				if h := fmt.Sprintf("%x", blocks[i].Hash); h != test.hash[i] {
					t.Errorf("%d/%d: Incorrect block hash %q != %q", testNo, i, h, test.hash[i])
				}

				i++
			}
		}
	}
}

func BenchmarkValidate(b *testing.B) {
	type block struct {
		data []byte
		hash [sha256.Size]byte
	}
	var blocks []block
	const blocksPerType = 100

	r := mrand.New(mrand.NewSource(0x136bea689e851))

	// Valid blocks.
	for i := 0; i < blocksPerType; i++ {
		var b block
		b.data = make([]byte, 128<<10)
		r.Read(b.data)
		b.hash = sha256.Sum256(b.data)
		blocks = append(blocks, b)
	}

	b.ReportAllocs()
	b.ResetTimer()

	for i := 0; i < b.N; i++ {
		for _, b := range blocks {
			Validate(b.data, b.hash[:])
		}
	}
}