// Copyright (C) 2014 The Syncthing Authors.
//
// This program is free software: you can redistribute it and/or modify it
// under the terms of the GNU General Public License as published by the Free
// Software Foundation, either version 3 of the License, or (at your option)
// any later version.
//
// This program is distributed in the hope that it will be useful, but WITHOUT
// ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
// FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for
// more details.
//
// You should have received a copy of the GNU General Public License along
// with this program. If not, see <http://www.gnu.org/licenses/>.

package model

import (
	"os"
	"path/filepath"
	"testing"

	"github.com/syncthing/syncthing/internal/config"
	"github.com/syncthing/syncthing/internal/protocol"
	"github.com/syncthing/syncthing/internal/scanner"

	"github.com/syndtr/goleveldb/leveldb"
	"github.com/syndtr/goleveldb/leveldb/storage"
)

var blocks = []protocol.BlockInfo{
	{Hash: []uint8{0xfa, 0x43, 0x23, 0x9b, 0xce, 0xe7, 0xb9, 0x7c, 0xa6, 0x2f, 0x0, 0x7c, 0xc6, 0x84, 0x87, 0x56, 0xa, 0x39, 0xe1, 0x9f, 0x74, 0xf3, 0xdd, 0xe7, 0x48, 0x6d, 0xb3, 0xf9, 0x8d, 0xf8, 0xe4, 0x71}}, // Zero'ed out block
	{Offset: 0, Size: 0x20000, Hash: []uint8{0x7e, 0xad, 0xbc, 0x36, 0xae, 0xbb, 0xcf, 0x74, 0x43, 0xe2, 0x7a, 0x5a, 0x4b, 0xb8, 0x5b, 0xce, 0xe6, 0x9e, 0x1e, 0x10, 0xf9, 0x8a, 0xbc, 0x77, 0x95, 0x2, 0x29, 0x60, 0x9e, 0x96, 0xae, 0x6c}},
	{Offset: 131072, Size: 0x20000, Hash: []uint8{0x3c, 0xc4, 0x20, 0xf4, 0xb, 0x2e, 0xcb, 0xb9, 0x5d, 0xce, 0x34, 0xa8, 0xc3, 0x92, 0xea, 0xf3, 0xda, 0x88, 0x33, 0xee, 0x7a, 0xb6, 0xe, 0xf1, 0x82, 0x5e, 0xb0, 0xa9, 0x26, 0xa9, 0xc0, 0xef}},
	{Offset: 262144, Size: 0x20000, Hash: []uint8{0x76, 0xa8, 0xc, 0x69, 0xd7, 0x5c, 0x52, 0xfd, 0xdf, 0x55, 0xef, 0x44, 0xc1, 0xd6, 0x25, 0x48, 0x4d, 0x98, 0x48, 0x4d, 0xaa, 0x50, 0xf6, 0x6b, 0x32, 0x47, 0x55, 0x81, 0x6b, 0xed, 0xee, 0xfb}},
	{Offset: 393216, Size: 0x20000, Hash: []uint8{0x44, 0x1e, 0xa4, 0xf2, 0x8d, 0x1f, 0xc3, 0x1b, 0x9d, 0xa5, 0x18, 0x5e, 0x59, 0x1b, 0xd8, 0x5c, 0xba, 0x7d, 0xb9, 0x8d, 0x70, 0x11, 0x5c, 0xea, 0xa1, 0x57, 0x4d, 0xcb, 0x3c, 0x5b, 0xf8, 0x6c}},
	{Offset: 524288, Size: 0x20000, Hash: []uint8{0x8, 0x40, 0xd0, 0x5e, 0x80, 0x0, 0x0, 0x7c, 0x8b, 0xb3, 0x8b, 0xf7, 0x7b, 0x23, 0x26, 0x28, 0xab, 0xda, 0xcf, 0x86, 0x8f, 0xc2, 0x8a, 0x39, 0xc6, 0xe6, 0x69, 0x59, 0x97, 0xb6, 0x1a, 0x43}},
	{Offset: 655360, Size: 0x20000, Hash: []uint8{0x38, 0x8e, 0x44, 0xcb, 0x30, 0xd8, 0x90, 0xf, 0xce, 0x7, 0x4b, 0x58, 0x86, 0xde, 0xce, 0x59, 0xa2, 0x46, 0xd2, 0xf9, 0xba, 0xaf, 0x35, 0x87, 0x38, 0xdf, 0xd2, 0xd, 0xf9, 0x45, 0xed, 0x91}},
	{Offset: 786432, Size: 0x20000, Hash: []uint8{0x32, 0x28, 0xcd, 0xf, 0x37, 0x21, 0xe5, 0xd4, 0x1e, 0x58, 0x87, 0x73, 0x8e, 0x36, 0xdf, 0xb2, 0x70, 0x78, 0x56, 0xc3, 0x42, 0xff, 0xf7, 0x8f, 0x37, 0x95, 0x0, 0x26, 0xa, 0xac, 0x54, 0x72}},
	{Offset: 917504, Size: 0x20000, Hash: []uint8{0x96, 0x6b, 0x15, 0x6b, 0xc4, 0xf, 0x19, 0x18, 0xca, 0xbb, 0x5f, 0xd6, 0xbb, 0xa2, 0xc6, 0x2a, 0xac, 0xbb, 0x8a, 0xb9, 0xce, 0xec, 0x4c, 0xdb, 0x78, 0xec, 0x57, 0x5d, 0x33, 0xf9, 0x8e, 0xaf}},
}

// Layout of the files: (indexes from the above array)
// 12345678 - Required file
// 02005008 - Existing file (currently in the index)
// 02340070 - Temp file on the disk

func TestHandleFile(t *testing.T) {
	// After the diff between required and existing we should:
	// Copy: 2, 5, 8
	// Pull: 1, 3, 4, 6, 7

	// Create existing file
	existingFile := protocol.FileInfo{
		Name:     "filex",
		Flags:    0,
		Modified: 0,
		Blocks: []protocol.BlockInfo{
			blocks[0], blocks[2], blocks[0], blocks[0],
			blocks[5], blocks[0], blocks[0], blocks[8],
		},
	}

	// Create target file
	requiredFile := existingFile
	requiredFile.Blocks = blocks[1:]

	db, _ := leveldb.Open(storage.NewMemStorage(), nil)
	m := NewModel(config.Wrap("/tmp/test", config.Configuration{}), "device", "syncthing", "dev", db)
	m.AddFolder(config.FolderConfiguration{ID: "default", Path: "testdata"})
	// Update index
	m.updateLocal("default", existingFile)

	p := Puller{
		folder: "default",
		dir:    "testdata",
		model:  m,
	}

	copyChan := make(chan copyBlocksState, 1)

	p.handleFile(requiredFile, copyChan, nil)

	// Receive the results
	toCopy := <-copyChan

	if len(toCopy.blocks) != 8 {
		t.Errorf("Unexpected count of copy blocks: %d != 8", len(toCopy.blocks))
	}

	for i, block := range toCopy.blocks {
		if string(block.Hash) != string(blocks[i+1].Hash) {
			t.Errorf("Block mismatch: %s != %s", block.String(), blocks[i+1].String())
		}
	}
}

func TestHandleFileWithTemp(t *testing.T) {
	// After diff between required and existing we should:
	// Copy: 2, 5, 8
	// Pull: 1, 3, 4, 6, 7

	// After dropping out blocks already on the temp file we should:
	// Copy: 5, 8
	// Pull: 1, 6

	// Create existing file
	existingFile := protocol.FileInfo{
		Name:     "file",
		Flags:    0,
		Modified: 0,
		Blocks: []protocol.BlockInfo{
			blocks[0], blocks[2], blocks[0], blocks[0],
			blocks[5], blocks[0], blocks[0], blocks[8],
		},
	}

	// Create target file
	requiredFile := existingFile
	requiredFile.Blocks = blocks[1:]

	db, _ := leveldb.Open(storage.NewMemStorage(), nil)
	m := NewModel(config.Wrap("/tmp/test", config.Configuration{}), "device", "syncthing", "dev", db)
	m.AddFolder(config.FolderConfiguration{ID: "default", Path: "testdata"})
	// Update index
	m.updateLocal("default", existingFile)

	p := Puller{
		folder: "default",
		dir:    "testdata",
		model:  m,
	}

	copyChan := make(chan copyBlocksState, 1)

	p.handleFile(requiredFile, copyChan, nil)

	// Receive the results
	toCopy := <-copyChan

	if len(toCopy.blocks) != 4 {
		t.Errorf("Unexpected count of copy blocks: %d != 4", len(toCopy.blocks))
	}

	for i, eq := range []int{1, 5, 6, 8} {
		if string(toCopy.blocks[i].Hash) != string(blocks[eq].Hash) {
			t.Errorf("Block mismatch: %s != %s", toCopy.blocks[i].String(), blocks[eq].String())
		}
	}
}

func TestCopierFinder(t *testing.T) {
	// After diff between required and existing we should:
	// Copy: 1, 2, 3, 4, 6, 7, 8
	// Since there is no existing file, nor a temp file

	// After dropping out blocks found locally:
	// Pull: 1, 5, 6, 8

	tempFile := filepath.Join("testdata", defTempNamer.TempName("file2"))
	err := os.Remove(tempFile)
	if err != nil && !os.IsNotExist(err) {
		t.Error(err)
	}

	// Create existing file
	existingFile := protocol.FileInfo{
		Name:     defTempNamer.TempName("file"),
		Flags:    0,
		Modified: 0,
		Blocks: []protocol.BlockInfo{
			blocks[0], blocks[2], blocks[3], blocks[4],
			blocks[0], blocks[0], blocks[7], blocks[0],
		},
	}

	// Create target file
	requiredFile := existingFile
	requiredFile.Blocks = blocks[1:]
	requiredFile.Name = "file2"

	fcfg := config.FolderConfiguration{ID: "default", Path: "testdata"}
	cfg := config.Configuration{Folders: []config.FolderConfiguration{fcfg}}

	db, _ := leveldb.Open(storage.NewMemStorage(), nil)
	m := NewModel(config.Wrap("/tmp/test", cfg), "device", "syncthing", "dev", db)
	m.AddFolder(fcfg)
	// Update index
	m.updateLocal("default", existingFile)

	iterFn := func(folder, file string, index uint32) bool {
		return true
	}

	// Verify that the blocks we say exist on file, really exist in the db.
	for _, idx := range []int{2, 3, 4, 7} {
		if m.finder.Iterate(blocks[idx].Hash, iterFn) == false {
			t.Error("Didn't find block")
		}
	}

	p := Puller{
		folder: "default",
		dir:    "testdata",
		model:  m,
	}

	copyChan := make(chan copyBlocksState)
	pullChan := make(chan pullBlockState, 4)
	finisherChan := make(chan *sharedPullerState, 1)

	// Run a single fetcher routine
	go p.copierRoutine(copyChan, pullChan, finisherChan, false)

	p.handleFile(requiredFile, copyChan, finisherChan)

	pulls := []pullBlockState{<-pullChan, <-pullChan, <-pullChan, <-pullChan}
	finish := <-finisherChan

	select {
	case <-pullChan:
		t.Fatal("Finisher channel has data to be read")
	case <-finisherChan:
		t.Fatal("Finisher channel has data to be read")
	default:
	}

	// Verify that the right blocks went into the pull list
	for i, eq := range []int{1, 5, 6, 8} {
		if string(pulls[i].block.Hash) != string(blocks[eq].Hash) {
			t.Errorf("Block %d mismatch: %s != %s", eq, pulls[i].block.String(), blocks[eq].String())
		}
		if string(finish.file.Blocks[eq-1].Hash) != string(blocks[eq].Hash) {
			t.Errorf("Block %d mismatch: %s != %s", eq, finish.file.Blocks[eq-1].String(), blocks[eq].String())
		}
	}

	// Verify that the fetched blocks have actually been written to the temp file
	blks, err := scanner.HashFile(tempFile, protocol.BlockSize)
	if err != nil {
		t.Log(err)
	}

	for _, eq := range []int{2, 3, 4, 7} {
		if string(blks[eq-1].Hash) != string(blocks[eq].Hash) {
			t.Errorf("Block %d mismatch: %s != %s", eq, blks[eq-1].String(), blocks[eq].String())
		}
	}
	finish.fd.Close()

	os.Remove(tempFile)
}

// Test that updating a file removes it's old blocks from the blockmap
func TestCopierCleanup(t *testing.T) {
	iterFn := func(folder, file string, index uint32) bool {
		return true
	}

	fcfg := config.FolderConfiguration{ID: "default", Path: "testdata"}
	cfg := config.Configuration{Folders: []config.FolderConfiguration{fcfg}}

	db, _ := leveldb.Open(storage.NewMemStorage(), nil)
	m := NewModel(config.Wrap("/tmp/test", cfg), "device", "syncthing", "dev", db)
	m.AddFolder(fcfg)

	// Create a file
	file := protocol.FileInfo{
		Name:     "test",
		Flags:    0,
		Modified: 0,
		Blocks:   []protocol.BlockInfo{blocks[0]},
	}

	// Add file to index
	m.updateLocal("default", file)

	if !m.finder.Iterate(blocks[0].Hash, iterFn) {
		t.Error("Expected block not found")
	}

	file.Blocks = []protocol.BlockInfo{blocks[1]}
	file.Version++
	// Update index (removing old blocks)
	m.updateLocal("default", file)

	if m.finder.Iterate(blocks[0].Hash, iterFn) {
		t.Error("Unexpected block found")
	}

	if !m.finder.Iterate(blocks[1].Hash, iterFn) {
		t.Error("Expected block not found")
	}

	file.Blocks = []protocol.BlockInfo{blocks[0]}
	file.Version++
	// Update index (removing old blocks)
	m.updateLocal("default", file)

	if !m.finder.Iterate(blocks[0].Hash, iterFn) {
		t.Error("Unexpected block found")
	}

	if m.finder.Iterate(blocks[1].Hash, iterFn) {
		t.Error("Expected block not found")
	}
}

// On the 10th iteration, we start hashing the content which we receive by
// following blockfinder's instructions. Make sure that the copier routine
// hashes the content when asked, and pulls if it fails to find the block.
func TestLastResortPulling(t *testing.T) {
	fcfg := config.FolderConfiguration{ID: "default", Path: "testdata"}
	cfg := config.Configuration{Folders: []config.FolderConfiguration{fcfg}}

	db, _ := leveldb.Open(storage.NewMemStorage(), nil)
	m := NewModel(config.Wrap("/tmp/test", cfg), "device", "syncthing", "dev", db)
	m.AddFolder(fcfg)

	// Add a file to index (with the incorrect block representation, as content
	// doesn't actually match the block list)
	file := protocol.FileInfo{
		Name:     "empty",
		Flags:    0,
		Modified: 0,
		Blocks:   []protocol.BlockInfo{blocks[0]},
	}
	m.updateLocal("default", file)

	// Pretend that we are handling a new file of the same content but
	// with a different name (causing to copy that particular block)
	file.Name = "newfile"

	iterFn := func(folder, file string, index uint32) bool {
		return true
	}

	// Check that that particular block is there
	if !m.finder.Iterate(blocks[0].Hash, iterFn) {
		t.Error("Expected block not found")
	}

	p := Puller{
		folder: "default",
		dir:    "testdata",
		model:  m,
	}

	copyChan := make(chan copyBlocksState)
	pullChan := make(chan pullBlockState, 1)
	finisherChan := make(chan *sharedPullerState, 1)

	// Run a single copier routine with checksumming enabled
	go p.copierRoutine(copyChan, pullChan, finisherChan, true)

	p.handleFile(file, copyChan, finisherChan)

	// Copier should hash empty file, realise that the region it has read
	// doesn't match the hash which was advertised by the block map, fix it
	// and ask to pull the block.
	<-pullChan

	// Verify that it did fix the incorrect hash.
	if m.finder.Iterate(blocks[0].Hash, iterFn) {
		t.Error("Found unexpected block")
	}

	if !m.finder.Iterate(scanner.SHA256OfNothing, iterFn) {
		t.Error("Expected block not found")
	}

	(<-finisherChan).fd.Close()
	os.Remove(filepath.Join("testdata", defTempNamer.TempName("newfile")))
}