package main

import (
	"bytes"
	"testing"
)

// A TestableVolumeManagerFactory creates a volume manager with one or more TestableVolumes.
// The factory function, and the TestableVolumes it returns, can use "t" to write
// logs, fail the current test, etc.
type TestableVolumeManagerFactory func(t *testing.T) []TestableVolume

// DoGenericVolumeTests runs a set of tests that every TestableVolume
// is expected to pass. It calls factory to create a new TestableVolume
// for each test case, to avoid leaking state between tests.
func DoGenericVolumeFunctionalTests(t *testing.T, factory TestableVolumeManagerFactory) {
	testGetBlock(t, factory, TestHash, TestBlock)
	testGetBlock(t, factory, EmptyHash, EmptyBlock)
	testPutRawBadDataGetBlock(t, factory, TestHash, TestBlock, []byte("baddata"))
	testPutRawBadDataGetBlock(t, factory, EmptyHash, EmptyBlock, []byte("baddata"))
	testPutBlock(t, factory, TestHash, TestBlock)
	testPutBlock(t, factory, EmptyHash, EmptyBlock)
	testPutBlockCorrupt(t, factory, TestHash, TestBlock, []byte("baddata"))
	testPutBlockCorrupt(t, factory, EmptyHash, EmptyBlock, []byte("baddata"))
}

// Put a block using PutRaw in just one volume and Get it using GetBlock
func testGetBlock(t *testing.T, factory TestableVolumeManagerFactory, testHash string, testBlock []byte) {
	testableVolumes := factory(t)
	defer testableVolumes[0].Teardown()
	defer testableVolumes[1].Teardown()
	defer KeepVM.Close()

	// Put testBlock in one volume
	testableVolumes[1].PutRaw(testHash, testBlock)

	// Get should pass
	buf, err := GetBlock(testHash)
	if err != nil {
		t.Fatalf("Error while getting block %s", err)
	}
	if bytes.Compare(buf, testBlock) != 0 {
		t.Errorf("Put succeeded but Get returned %+v, expected %+v", buf, testBlock)
	}
}

// Put a bad block using PutRaw and get it.
func testPutRawBadDataGetBlock(t *testing.T, factory TestableVolumeManagerFactory,
	testHash string, testBlock []byte, badData []byte) {
	testableVolumes := factory(t)
	defer testableVolumes[0].Teardown()
	defer testableVolumes[1].Teardown()
	defer KeepVM.Close()

	// Put bad data for testHash in both volumes
	testableVolumes[0].PutRaw(testHash, badData)
	testableVolumes[1].PutRaw(testHash, badData)

	// Get should fail
	_, err := GetBlock(testHash)
	if err == nil {
		t.Fatalf("Expected error while getting corrupt block %v", testHash)
	}
}

// Invoke PutBlock twice to ensure CompareAndTouch path is tested.
func testPutBlock(t *testing.T, factory TestableVolumeManagerFactory, testHash string, testBlock []byte) {
	testableVolumes := factory(t)
	defer testableVolumes[0].Teardown()
	defer testableVolumes[1].Teardown()
	defer KeepVM.Close()

	// PutBlock
	if err := PutBlock(testBlock, testHash); err != nil {
		t.Fatalf("Error during PutBlock: %s", err)
	}

	// Check that PutBlock succeeds again even after CompareAndTouch
	if err := PutBlock(testBlock, testHash); err != nil {
		t.Fatalf("Error during PutBlock: %s", err)
	}

	// Check that PutBlock stored the data as expected
	buf, err := GetBlock(testHash)
	if err != nil {
		t.Fatalf("Error during GetBlock for %q: %s", testHash, err)
	} else if bytes.Compare(buf, testBlock) != 0 {
		t.Errorf("Get response incorrect. Expected %q; found %q", testBlock, buf)
	}
}

// Put a bad block using PutRaw, overwrite it using PutBlock and get it.
func testPutBlockCorrupt(t *testing.T, factory TestableVolumeManagerFactory,
	testHash string, testBlock []byte, badData []byte) {
	testableVolumes := factory(t)
	defer testableVolumes[0].Teardown()
	defer testableVolumes[1].Teardown()
	defer KeepVM.Close()

	// Put bad data for testHash in both volumes
	testableVolumes[0].PutRaw(testHash, badData)
	testableVolumes[1].PutRaw(testHash, badData)

	// Check that PutBlock with good data succeeds
	if err := PutBlock(testBlock, testHash); err != nil {
		t.Fatalf("Error during PutBlock for %q: %s", testHash, err)
	}

	// Put succeeded and overwrote the badData in one volume,
	// and Get should return the testBlock now, ignoring the bad data.
	buf, err := GetBlock(testHash)
	if err != nil {
		t.Fatalf("Error during GetBlock for %q: %s", testHash, err)
	} else if bytes.Compare(buf, testBlock) != 0 {
		t.Errorf("Get response incorrect. Expected %q; found %q", testBlock, buf)
	}
}