package simapp

import (
	"encoding/json"
	"flag"
	"fmt"
	"io"
	"io/ioutil"
	"math/rand"
	"os"
	"testing"
	"time"

	"github.com/stretchr/testify/require"

	abci "github.com/tendermint/tendermint/abci/types"
	dbm "github.com/tendermint/tendermint/libs/db"
	"github.com/tendermint/tendermint/libs/log"

	"github.com/cosmos/cosmos-sdk/baseapp"
	sdk "github.com/cosmos/cosmos-sdk/types"
	authsim "github.com/cosmos/cosmos-sdk/x/auth/simulation"
	"github.com/cosmos/cosmos-sdk/x/bank"
	distrsim "github.com/cosmos/cosmos-sdk/x/distribution/simulation"
	govsim "github.com/cosmos/cosmos-sdk/x/gov/simulation"
	paramsim "github.com/cosmos/cosmos-sdk/x/params/simulation"
	"github.com/cosmos/cosmos-sdk/x/simulation"
	slashingsim "github.com/cosmos/cosmos-sdk/x/slashing/simulation"
	"github.com/cosmos/cosmos-sdk/x/staking"
	stakingsim "github.com/cosmos/cosmos-sdk/x/staking/simulation"
)

func init() {
	flag.StringVar(&genesisFile, "SimulationGenesis", "", "custom simulation genesis file; cannot be used with params file")
	flag.StringVar(&paramsFile, "SimulationParams", "", "custom simulation params file which overrides any random params; cannot be used with genesis")
	flag.Int64Var(&seed, "SimulationSeed", 42, "simulation random seed")
	flag.IntVar(&numBlocks, "SimulationNumBlocks", 500, "number of blocks")
	flag.IntVar(&blockSize, "SimulationBlockSize", 200, "operations per block")
	flag.BoolVar(&enabled, "SimulationEnabled", false, "enable the simulation")
	flag.BoolVar(&verbose, "SimulationVerbose", false, "verbose log output")
	flag.BoolVar(&lean, "SimulationLean", false, "lean simulation log output")
	flag.BoolVar(&commit, "SimulationCommit", false, "have the simulation commit")
	flag.IntVar(&period, "SimulationPeriod", 1, "run slow invariants only once every period assertions")
	flag.BoolVar(&onOperation, "SimulateEveryOperation", false, "run slow invariants every operation")
	flag.BoolVar(&allInvariants, "PrintAllInvariants", false, "print all invariants if a broken invariant is found")
}

// helper function for populating input for SimulateFromSeed
func getSimulateFromSeedInput(tb testing.TB, w io.Writer, app *SimApp) (
	testing.TB, io.Writer, *baseapp.BaseApp, simulation.AppStateFn, int64,
	simulation.WeightedOperations, sdk.Invariants, int, int, bool, bool, bool, bool) {

	return tb, w, app.BaseApp, appStateFn, seed,
		testAndRunTxs(app), invariants(app), numBlocks, blockSize, commit, lean, onOperation, allInvariants
}

func appStateFn(
	r *rand.Rand, accs []simulation.Account, genesisTimestamp time.Time,
) (appState json.RawMessage, simAccs []simulation.Account, chainID string) {

	cdc := MakeCodec()

	switch {
	case paramsFile != "" && genesisFile != "":
		panic("cannot provide both a genesis file and a params file")

	case genesisFile != "":
		appState, simAccs, chainID = AppStateFromGenesisFileFn(r, accs, genesisTimestamp)

	case paramsFile != "":
		appParams := make(simulation.AppParams)
		bz, err := ioutil.ReadFile(paramsFile)
		if err != nil {
			panic(err)
		}

		cdc.MustUnmarshalJSON(bz, &appParams)
		appState, simAccs, chainID = appStateRandomizedFn(r, accs, genesisTimestamp, appParams)

	default:
		appParams := make(simulation.AppParams)
		appState, simAccs, chainID = appStateRandomizedFn(r, accs, genesisTimestamp, appParams)
	}

	return appState, simAccs, chainID
}

// TODO refactor out random initialization code to the modules
func appStateRandomizedFn(
	r *rand.Rand, accs []simulation.Account, genesisTimestamp time.Time, appParams simulation.AppParams,
) (json.RawMessage, []simulation.Account, string) {

	cdc := MakeCodec()
	genesisState := NewDefaultGenesisState()

	var (
		amount             int64
		numInitiallyBonded int64
	)

	appParams.GetOrGenerate(cdc, StakePerAccount, &amount, r,
		func(r *rand.Rand) { amount = int64(r.Intn(1e12)) })
	appParams.GetOrGenerate(cdc, InitiallyBondedValidators, &amount, r,
		func(r *rand.Rand) { numInitiallyBonded = int64(r.Intn(250)) })

	numAccs := int64(len(accs))
	if numInitiallyBonded > numAccs {
		numInitiallyBonded = numAccs
	}

	fmt.Printf(
		`Selected randomly generated parameters for simulated genesis:
{
  stake_per_account: "%v",
  initially_bonded_validators: "%v"
}
`, amount, numInitiallyBonded,
	)

	GenGenesisAccounts(cdc, r, accs, genesisTimestamp, amount, numInitiallyBonded, genesisState)
	GenAuthGenesisState(cdc, r, appParams, genesisState)
	GenBankGenesisState(cdc, r, appParams, genesisState)
	GenSupplyGenesisState(cdc, amount, numInitiallyBonded, int64(len(accs)), genesisState)
	GenGovGenesisState(cdc, r, appParams, genesisState)
	GenMintGenesisState(cdc, r, appParams, genesisState)
	GenDistrGenesisState(cdc, r, appParams, genesisState)
	stakingGen := GenStakingGenesisState(cdc, r, accs, amount, numAccs, numInitiallyBonded, appParams, genesisState)
	GenSlashingGenesisState(cdc, r, stakingGen, appParams, genesisState)

	appState, err := MakeCodec().MarshalJSON(genesisState)
	if err != nil {
		panic(err)
	}

	return appState, accs, "simulation"
}

func testAndRunTxs(app *SimApp) []simulation.WeightedOperation {
	cdc := MakeCodec()
	ap := make(simulation.AppParams)

	if paramsFile != "" {
		bz, err := ioutil.ReadFile(paramsFile)
		if err != nil {
			panic(err)
		}

		cdc.MustUnmarshalJSON(bz, &ap)
	}

	return []simulation.WeightedOperation{
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightDeductFee, &v, nil,
					func(_ *rand.Rand) {
						v = 5
					})
				return v
			}(nil),
			authsim.SimulateDeductFee(app.accountKeeper, app.supplyKeeper),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightMsgSend, &v, nil,
					func(_ *rand.Rand) {
						v = 100
					})
				return v
			}(nil),
			bank.SimulateMsgSend(app.accountKeeper, app.bankKeeper),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightSingleInputMsgMultiSend, &v, nil,
					func(_ *rand.Rand) {
						v = 10
					})
				return v
			}(nil),
			bank.SimulateSingleInputMsgMultiSend(app.accountKeeper, app.bankKeeper),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightMsgSetWithdrawAddress, &v, nil,
					func(_ *rand.Rand) {
						v = 50
					})
				return v
			}(nil),
			distrsim.SimulateMsgSetWithdrawAddress(app.accountKeeper, app.distrKeeper),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightMsgWithdrawDelegationReward, &v, nil,
					func(_ *rand.Rand) {
						v = 50
					})
				return v
			}(nil),
			distrsim.SimulateMsgWithdrawDelegatorReward(app.accountKeeper, app.distrKeeper),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightMsgWithdrawValidatorCommission, &v, nil,
					func(_ *rand.Rand) {
						v = 50
					})
				return v
			}(nil),
			distrsim.SimulateMsgWithdrawValidatorCommission(app.accountKeeper, app.distrKeeper),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightSubmitVotingSlashingTextProposal, &v, nil,
					func(_ *rand.Rand) {
						v = 5
					})
				return v
			}(nil),
			govsim.SimulateSubmittingVotingAndSlashingForProposal(app.govKeeper, govsim.SimulateTextProposalContent),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightSubmitVotingSlashingCommunitySpendProposal, &v, nil,
					func(_ *rand.Rand) {
						v = 5
					})
				return v
			}(nil),
			govsim.SimulateSubmittingVotingAndSlashingForProposal(app.govKeeper, distrsim.SimulateCommunityPoolSpendProposalContent(app.distrKeeper)),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightSubmitVotingSlashingParamChangeProposal, &v, nil,
					func(_ *rand.Rand) {
						v = 5
					})
				return v
			}(nil),
			govsim.SimulateSubmittingVotingAndSlashingForProposal(app.govKeeper, paramsim.SimulateParamChangeProposalContent),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightMsgDeposit, &v, nil,
					func(_ *rand.Rand) {
						v = 100
					})
				return v
			}(nil),
			govsim.SimulateMsgDeposit(app.govKeeper),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightMsgCreateValidator, &v, nil,
					func(_ *rand.Rand) {
						v = 100
					})
				return v
			}(nil),
			stakingsim.SimulateMsgCreateValidator(app.accountKeeper, app.stakingKeeper),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightMsgEditValidator, &v, nil,
					func(_ *rand.Rand) {
						v = 5
					})
				return v
			}(nil),
			stakingsim.SimulateMsgEditValidator(app.stakingKeeper),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightMsgDelegate, &v, nil,
					func(_ *rand.Rand) {
						v = 100
					})
				return v
			}(nil),
			stakingsim.SimulateMsgDelegate(app.accountKeeper, app.stakingKeeper),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightMsgUndelegate, &v, nil,
					func(_ *rand.Rand) {
						v = 100
					})
				return v
			}(nil),
			stakingsim.SimulateMsgUndelegate(app.accountKeeper, app.stakingKeeper),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightMsgBeginRedelegate, &v, nil,
					func(_ *rand.Rand) {
						v = 100
					})
				return v
			}(nil),
			stakingsim.SimulateMsgBeginRedelegate(app.accountKeeper, app.stakingKeeper),
		},
		{
			func(_ *rand.Rand) int {
				var v int
				ap.GetOrGenerate(cdc, OpWeightMsgUnjail, &v, nil,
					func(_ *rand.Rand) {
						v = 100
					})
				return v
			}(nil),
			slashingsim.SimulateMsgUnjail(app.slashingKeeper),
		},
	}
}

func invariants(app *SimApp) []sdk.Invariant {
	// TODO: fix PeriodicInvariants, it doesn't seem to call individual invariants for a period of 1
	// Ref: https://github.com/cosmos/cosmos-sdk/issues/4631
	if period == 1 {
		return app.crisisKeeper.Invariants()
	}
	return simulation.PeriodicInvariants(app.crisisKeeper.Invariants(), period, 0)
}

// Pass this in as an option to use a dbStoreAdapter instead of an IAVLStore for simulation speed.
func fauxMerkleModeOpt(bapp *baseapp.BaseApp) {
	bapp.SetFauxMerkleMode()
}

// Profile with:
// /usr/local/go/bin/go test -benchmem -run=^$ github.com/cosmos/cosmos-sdk/simapp -bench ^BenchmarkFullAppSimulation$ -SimulationCommit=true -cpuprofile cpu.out
func BenchmarkFullAppSimulation(b *testing.B) {
	logger := log.NewNopLogger()

	var db dbm.DB
	dir, _ := ioutil.TempDir("", "goleveldb-app-sim")
	db, _ = sdk.NewLevelDB("Simulation", dir)
	defer func() {
		db.Close()
		os.RemoveAll(dir)
	}()
	app := NewSimApp(logger, db, nil, true, 0)

	// Run randomized simulation
	// TODO parameterize numbers, save for a later PR
	_, err := simulation.SimulateFromSeed(getSimulateFromSeedInput(b, os.Stdout, app))
	if err != nil {
		fmt.Println(err)
		b.Fail()
	}
	if commit {
		fmt.Println("GoLevelDB Stats")
		fmt.Println(db.Stats()["leveldb.stats"])
		fmt.Println("GoLevelDB cached block size", db.Stats()["leveldb.cachedblock"])
	}
}

func TestFullAppSimulation(t *testing.T) {
	if !enabled {
		t.Skip("Skipping application simulation")
	}

	var logger log.Logger

	if verbose {
		logger = log.TestingLogger()
	} else {
		logger = log.NewNopLogger()
	}

	var db dbm.DB
	dir, _ := ioutil.TempDir("", "goleveldb-app-sim")
	db, _ = sdk.NewLevelDB("Simulation", dir)

	defer func() {
		db.Close()
		os.RemoveAll(dir)
	}()

	app := NewSimApp(logger, db, nil, true, 0, fauxMerkleModeOpt)
	require.Equal(t, "SimApp", app.Name())

	// Run randomized simulation
	_, err := simulation.SimulateFromSeed(getSimulateFromSeedInput(t, os.Stdout, app))
	if commit {
		// for memdb:
		// fmt.Println("Database Size", db.Stats()["database.size"])
		fmt.Println("GoLevelDB Stats")
		fmt.Println(db.Stats()["leveldb.stats"])
		fmt.Println("GoLevelDB cached block size", db.Stats()["leveldb.cachedblock"])
	}

	require.Nil(t, err)
}

func TestAppImportExport(t *testing.T) {
	if !enabled {
		t.Skip("Skipping application import/export simulation")
	}

	var logger log.Logger
	if verbose {
		logger = log.TestingLogger()
	} else {
		logger = log.NewNopLogger()
	}

	var db dbm.DB
	dir, _ := ioutil.TempDir("", "goleveldb-app-sim")
	db, _ = sdk.NewLevelDB("Simulation", dir)

	defer func() {
		db.Close()
		os.RemoveAll(dir)
	}()

	app := NewSimApp(logger, db, nil, true, 0, fauxMerkleModeOpt)
	require.Equal(t, "SimApp", app.Name())

	// Run randomized simulation
	_, err := simulation.SimulateFromSeed(getSimulateFromSeedInput(t, os.Stdout, app))

	if commit {
		// for memdb:
		// fmt.Println("Database Size", db.Stats()["database.size"])
		fmt.Println("GoLevelDB Stats")
		fmt.Println(db.Stats()["leveldb.stats"])
		fmt.Println("GoLevelDB cached block size", db.Stats()["leveldb.cachedblock"])
	}

	require.Nil(t, err)
	fmt.Printf("Exporting genesis...\n")

	appState, _, err := app.ExportAppStateAndValidators(false, []string{})
	require.NoError(t, err)
	fmt.Printf("Importing genesis...\n")

	newDir, _ := ioutil.TempDir("", "goleveldb-app-sim-2")
	newDB, _ := sdk.NewLevelDB("Simulation-2", dir)

	defer func() {
		newDB.Close()
		os.RemoveAll(newDir)
	}()

	newApp := NewSimApp(log.NewNopLogger(), newDB, nil, true, 0, fauxMerkleModeOpt)
	require.Equal(t, "SimApp", newApp.Name())

	var genesisState GenesisState
	err = app.cdc.UnmarshalJSON(appState, &genesisState)
	if err != nil {
		panic(err)
	}

	ctxB := newApp.NewContext(true, abci.Header{})
	newApp.mm.InitGenesis(ctxB, genesisState)

	fmt.Printf("Comparing stores...\n")
	ctxA := app.NewContext(true, abci.Header{})

	type StoreKeysPrefixes struct {
		A        sdk.StoreKey
		B        sdk.StoreKey
		Prefixes [][]byte
	}

	storeKeysPrefixes := []StoreKeysPrefixes{
		{app.keyMain, newApp.keyMain, [][]byte{}},
		{app.keyAccount, newApp.keyAccount, [][]byte{}},
		{app.keyStaking, newApp.keyStaking, [][]byte{staking.UnbondingQueueKey,
			staking.RedelegationQueueKey, staking.ValidatorQueueKey}}, // ordering may change but it doesn't matter
		{app.keySlashing, newApp.keySlashing, [][]byte{}},
		{app.keyMint, newApp.keyMint, [][]byte{}},
		{app.keyDistr, newApp.keyDistr, [][]byte{}},
		{app.keySupply, newApp.keySupply, [][]byte{}},
		{app.keyParams, newApp.keyParams, [][]byte{}},
		{app.keyGov, newApp.keyGov, [][]byte{}},
	}

	for _, storeKeysPrefix := range storeKeysPrefixes {
		storeKeyA := storeKeysPrefix.A
		storeKeyB := storeKeysPrefix.B
		prefixes := storeKeysPrefix.Prefixes
		storeA := ctxA.KVStore(storeKeyA)
		storeB := ctxB.KVStore(storeKeyB)
		kvA, kvB, count, equal := sdk.DiffKVStores(storeA, storeB, prefixes)
		fmt.Printf("Compared %d key/value pairs between %s and %s\n", count, storeKeyA, storeKeyB)
		require.True(t, equal, GetSimulationLog(storeKeyA.Name(), app.cdc, newApp.cdc, kvA, kvB))
	}

}

func TestAppSimulationAfterImport(t *testing.T) {
	if !enabled {
		t.Skip("Skipping application simulation after import")
	}

	var logger log.Logger
	if verbose {
		logger = log.TestingLogger()
	} else {
		logger = log.NewNopLogger()
	}

	dir, _ := ioutil.TempDir("", "goleveldb-app-sim")
	db, _ := sdk.NewLevelDB("Simulation", dir)

	defer func() {
		db.Close()
		os.RemoveAll(dir)
	}()

	app := NewSimApp(logger, db, nil, true, 0, fauxMerkleModeOpt)
	require.Equal(t, "SimApp", app.Name())

	// Run randomized simulation
	stopEarly, err := simulation.SimulateFromSeed(getSimulateFromSeedInput(t, os.Stdout, app))

	if commit {
		// for memdb:
		// fmt.Println("Database Size", db.Stats()["database.size"])
		fmt.Println("GoLevelDB Stats")
		fmt.Println(db.Stats()["leveldb.stats"])
		fmt.Println("GoLevelDB cached block size", db.Stats()["leveldb.cachedblock"])
	}

	require.Nil(t, err)

	if stopEarly {
		// we can't export or import a zero-validator genesis
		fmt.Printf("We can't export or import a zero-validator genesis, exiting test...\n")
		return
	}

	fmt.Printf("Exporting genesis...\n")

	appState, _, err := app.ExportAppStateAndValidators(true, []string{})
	if err != nil {
		panic(err)
	}

	fmt.Printf("Importing genesis...\n")

	newDir, _ := ioutil.TempDir("", "goleveldb-app-sim-2")
	newDB, _ := sdk.NewLevelDB("Simulation-2", dir)

	defer func() {
		newDB.Close()
		os.RemoveAll(newDir)
	}()

	newApp := NewSimApp(log.NewNopLogger(), newDB, nil, true, 0, fauxMerkleModeOpt)
	require.Equal(t, "SimApp", newApp.Name())
	newApp.InitChain(abci.RequestInitChain{
		AppStateBytes: appState,
	})

	// Run randomized simulation on imported app
	_, err = simulation.SimulateFromSeed(getSimulateFromSeedInput(t, os.Stdout, newApp))
	require.Nil(t, err)
}

// TODO: Make another test for the fuzzer itself, which just has noOp txs
// and doesn't depend on the application.
func TestAppStateDeterminism(t *testing.T) {
	if !enabled {
		t.Skip("Skipping application simulation")
	}

	numSeeds := 3
	numTimesToRunPerSeed := 5
	appHashList := make([]json.RawMessage, numTimesToRunPerSeed)

	for i := 0; i < numSeeds; i++ {
		seed := rand.Int63()
		for j := 0; j < numTimesToRunPerSeed; j++ {
			logger := log.NewNopLogger()
			db := dbm.NewMemDB()
			app := NewSimApp(logger, db, nil, true, 0)

			// Run randomized simulation
			simulation.SimulateFromSeed(
				t, os.Stdout, app.BaseApp, appStateFn, seed,
				testAndRunTxs(app),
				[]sdk.Invariant{},
				50,
				100,
				true,
				false,
				false,
				false,
			)
			appHash := app.LastCommitID().Hash
			appHashList[j] = appHash
		}
		for k := 1; k < numTimesToRunPerSeed; k++ {
			require.Equal(t, appHashList[0], appHashList[k], "appHash list: %v", appHashList)
		}
	}
}

func BenchmarkInvariants(b *testing.B) {
	logger := log.NewNopLogger()
	dir, _ := ioutil.TempDir("", "goleveldb-app-invariant-bench")
	db, _ := sdk.NewLevelDB("simulation", dir)

	defer func() {
		db.Close()
		os.RemoveAll(dir)
	}()

	app := NewSimApp(logger, db, nil, true, 0)

	// 2. Run parameterized simulation (w/o invariants)
	_, err := simulation.SimulateFromSeed(
		b, ioutil.Discard, app.BaseApp, appStateFn, seed, testAndRunTxs(app),
		[]sdk.Invariant{}, numBlocks, blockSize, commit, lean, onOperation, false,
	)
	if err != nil {
		fmt.Println(err)
		b.FailNow()
	}

	ctx := app.NewContext(true, abci.Header{Height: app.LastBlockHeight() + 1})

	// 3. Benchmark each invariant separately
	//
	// NOTE: We use the crisis keeper as it has all the invariants registered with
	// their respective metadata which makes it useful for testing/benchmarking.
	for _, cr := range app.crisisKeeper.Routes() {
		b.Run(fmt.Sprintf("%s/%s", cr.ModuleName, cr.Route), func(b *testing.B) {
			if res, stop := cr.Invar(ctx); stop {
				fmt.Printf("broken invariant at block %d of %d\n%s", ctx.BlockHeight()-1, numBlocks, res)
				b.FailNow()
			}
		})
	}
}