/*
Copyright 2021 Erigon contributors

Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at

	http://www.apache.org/licenses/LICENSE-2.0

Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/
package kvcache

import (
	"context"
	"fmt"
	"sync"
	"testing"

	"github.com/ledgerwatch/erigon-lib/common"
	"github.com/ledgerwatch/erigon-lib/gointerfaces"
	"github.com/ledgerwatch/erigon-lib/gointerfaces/remote"
	"github.com/ledgerwatch/erigon-lib/kv"
	"github.com/ledgerwatch/erigon-lib/kv/memdb"
	"github.com/stretchr/testify/require"
)

func TestEvictionInUnexpectedOrder(t *testing.T) {
	// Order: View - 2, OnNewBlock - 2, View - 5, View - 6, OnNewBlock - 3, OnNewBlock - 4, View - 5, OnNewBlock - 5, OnNewBlock - 100
	require := require.New(t)
	cfg := DefaultCoherentConfig
	cfg.KeysLimit = 3
	cfg.NewBlockWait = 0
	c := New(cfg)
	c.selectOrCreateRoot(2)
	require.Equal(1, len(c.roots))
	require.Equal(0, int(c.latestViewID))
	require.False(c.roots[2].isCanonical)

	c.add([]byte{1}, nil, c.roots[2], 2)
	require.Equal(0, c.stateEvict.Len())

	c.advanceRoot(2)
	require.Equal(1, len(c.roots))
	require.Equal(2, int(c.latestViewID))
	require.True(c.roots[2].isCanonical)

	c.add([]byte{1}, nil, c.roots[2], 2)
	require.Equal(1, c.stateEvict.Len())

	c.selectOrCreateRoot(5)
	require.Equal(2, len(c.roots))
	require.Equal(2, int(c.latestViewID))
	require.False(c.roots[5].isCanonical)

	c.add([]byte{2}, nil, c.roots[5], 5) // not added to evict list
	require.Equal(1, c.stateEvict.Len())
	c.add([]byte{2}, nil, c.roots[2], 2) // added to evict list, because it's latest view
	require.Equal(2, c.stateEvict.Len())

	c.selectOrCreateRoot(6)
	require.Equal(3, len(c.roots))
	require.Equal(2, int(c.latestViewID))
	require.False(c.roots[6].isCanonical) // parrent exists, but parent has isCanonical=false

	c.advanceRoot(3)
	require.Equal(4, len(c.roots))
	require.Equal(3, int(c.latestViewID))
	require.True(c.roots[3].isCanonical)

	c.advanceRoot(4)
	require.Equal(5, len(c.roots))
	require.Equal(4, int(c.latestViewID))
	require.True(c.roots[4].isCanonical)

	c.selectOrCreateRoot(5)
	require.Equal(5, len(c.roots))
	require.Equal(4, int(c.latestViewID))
	require.False(c.roots[5].isCanonical)

	c.advanceRoot(5)
	require.Equal(5, len(c.roots))
	require.Equal(5, int(c.latestViewID))
	require.True(c.roots[5].isCanonical)

	c.advanceRoot(100)
	require.Equal(6, len(c.roots))
	require.Equal(100, int(c.latestViewID))
	require.True(c.roots[100].isCanonical)

	//c.add([]byte{1}, nil, c.roots[2], 2)
	require.Equal(0, c.latestStateView.cache.Len())
	require.Equal(0, c.stateEvict.Len())
}

func TestEviction(t *testing.T) {
	require, ctx := require.New(t), context.Background()
	cfg := DefaultCoherentConfig
	cfg.KeysLimit = 3
	cfg.NewBlockWait = 0
	c := New(cfg)
	db := memdb.NewTestDB(t)
	k1, k2 := [20]byte{1}, [20]byte{2}

	var id uint64
	_ = db.Update(ctx, func(tx kv.RwTx) error {
		_ = tx.Put(kv.PlainState, k1[:], []byte{1})
		cacheView, _ := c.View(ctx, tx)
		view := cacheView.(*CoherentView)
		id = tx.ViewID()
		_, _ = c.Get(k1[:], tx, view.viewID)
		_, _ = c.Get([]byte{1}, tx, view.viewID)
		_, _ = c.Get([]byte{2}, tx, view.viewID)
		_, _ = c.Get([]byte{3}, tx, view.viewID)
		//require.Equal(c.roots[c.latestViewID].cache.Len(), c.stateEvict.Len())
		return nil
	})
	require.Equal(0, c.stateEvict.Len())
	//require.Equal(c.roots[c.latestViewID].cache.Len(), c.stateEvict.Len())
	c.OnNewBlock(&remote.StateChangeBatch{
		DatabaseViewID: id + 1,
		ChangeBatch: []*remote.StateChange{
			{
				Direction: remote.Direction_FORWARD,
				Changes: []*remote.AccountChange{{
					Action:  remote.Action_UPSERT,
					Address: gointerfaces.ConvertAddressToH160(k1),
					Data:    []byte{2},
				}},
			},
		},
	})
	require.Equal(1, c.stateEvict.Len())
	require.Equal(c.roots[c.latestViewID].cache.Len(), c.stateEvict.Len())
	_ = db.Update(ctx, func(tx kv.RwTx) error {
		_ = tx.Put(kv.PlainState, k1[:], []byte{1})
		cacheView, _ := c.View(ctx, tx)
		view := cacheView.(*CoherentView)
		id = tx.ViewID()
		_, _ = c.Get(k1[:], tx, view.viewID)
		_, _ = c.Get(k2[:], tx, view.viewID)
		_, _ = c.Get([]byte{5}, tx, view.viewID)
		_, _ = c.Get([]byte{6}, tx, view.viewID)
		return nil
	})
	require.Equal(c.roots[c.latestViewID].cache.Len(), c.stateEvict.Len())
	require.Equal(cfg.KeysLimit, c.stateEvict.Len())
}

func TestAPI(t *testing.T) {
	require := require.New(t)
	c := New(DefaultCoherentConfig)
	k1, k2 := [20]byte{1}, [20]byte{2}
	db := memdb.NewTestDB(t)
	get := func(key [20]byte, expectTxnID uint64) (res [1]chan []byte) {
		wg := sync.WaitGroup{}
		for i := 0; i < len(res); i++ {
			wg.Add(1)
			res[i] = make(chan []byte)
			go func(out chan []byte) {
				require.NoError(db.View(context.Background(), func(tx kv.Tx) error {
					if expectTxnID != tx.ViewID() {
						panic(fmt.Sprintf("epxected: %d, got: %d", expectTxnID, tx.ViewID()))
					}
					wg.Done()
					cacheView, err := c.View(context.Background(), tx)
					view := cacheView.(*CoherentView)
					if err != nil {
						panic(err)
					}
					v, err := c.Get(key[:], tx, view.viewID)
					if err != nil {
						panic(err)
					}
					out <- common.Copy(v)
					return nil
				}))
			}(res[i])
		}
		wg.Wait() // ensure that all goroutines started their transactions
		return res
	}
	put := func(k, v []byte) uint64 {
		var txID uint64
		require.NoError(db.Update(context.Background(), func(tx kv.RwTx) error {
			_ = tx.Put(kv.PlainState, k, v)
			txID = tx.ViewID()
			return nil
		}))
		return txID
	}
	// block 1 - represents existing state (no notifications about this data will come to client)
	txID1 := put(k2[:], []byte{42})

	wg := sync.WaitGroup{}

	res1, res2 := get(k1, txID1), get(k2, txID1) // will return immediately
	wg.Add(1)
	go func() {
		defer wg.Done()
		for i := range res1 {
			require.Nil(<-res1[i])
		}
		for i := range res2 {
			require.Equal([]byte{42}, <-res2[i])
		}
		fmt.Printf("done1: \n")
	}()

	txID2 := put(k1[:], []byte{2})
	fmt.Printf("-----1 %d, %d\n", txID1, txID2)
	res3, res4 := get(k1, txID2), get(k2, txID2) // will see View of transaction 2
	txID3 := put(k1[:], []byte{3})               // even if core already on block 3

	c.OnNewBlock(&remote.StateChangeBatch{
		DatabaseViewID:      txID2,
		PendingBlockBaseFee: 1,
		ChangeBatch: []*remote.StateChange{
			{
				Direction:   remote.Direction_FORWARD,
				BlockHeight: 2,
				BlockHash:   gointerfaces.ConvertHashToH256([32]byte{}),
				Changes: []*remote.AccountChange{{
					Action:  remote.Action_UPSERT,
					Address: gointerfaces.ConvertAddressToH160(k1),
					Data:    []byte{2},
				}},
			},
		},
	})

	wg.Add(1)
	go func() {
		defer wg.Done()
		for i := range res3 {
			require.Equal([]byte{2}, <-res3[i])
		}
		for i := range res4 {
			require.Equal([]byte{42}, <-res4[i])
		}
		fmt.Printf("done2: \n")
	}()
	fmt.Printf("-----2\n")

	res5, res6 := get(k1, txID3), get(k2, txID3) // will see View of transaction 3, even if notification has not enough changes
	c.OnNewBlock(&remote.StateChangeBatch{
		DatabaseViewID:      txID3,
		PendingBlockBaseFee: 1,
		ChangeBatch: []*remote.StateChange{
			{
				Direction:   remote.Direction_FORWARD,
				BlockHeight: 3,
				BlockHash:   gointerfaces.ConvertHashToH256([32]byte{}),
				Changes: []*remote.AccountChange{{
					Action:  remote.Action_UPSERT,
					Address: gointerfaces.ConvertAddressToH160(k1),
					Data:    []byte{3},
				}},
			},
		},
	})

	wg.Add(1)
	go func() {
		defer wg.Done()
		for i := range res5 {
			require.Equal([]byte{3}, <-res5[i])
		}
		fmt.Printf("-----21\n")
		for i := range res6 {
			require.Equal([]byte{42}, <-res6[i])
		}
		fmt.Printf("done3: \n")
	}()
	fmt.Printf("-----3\n")
	txID4 := put(k1[:], []byte{2})
	_ = txID4
	c.OnNewBlock(&remote.StateChangeBatch{
		DatabaseViewID:      txID4,
		PendingBlockBaseFee: 1,
		ChangeBatch: []*remote.StateChange{
			{
				Direction:   remote.Direction_UNWIND,
				BlockHeight: 2,
				BlockHash:   gointerfaces.ConvertHashToH256([32]byte{}),
				Changes: []*remote.AccountChange{{
					Action:  remote.Action_UPSERT,
					Address: gointerfaces.ConvertAddressToH160(k1),
					Data:    []byte{2},
				}},
			},
		},
	})
	fmt.Printf("-----4\n")
	txID5 := put(k1[:], []byte{4}) // reorg to new chain
	c.OnNewBlock(&remote.StateChangeBatch{
		DatabaseViewID:      txID4,
		PendingBlockBaseFee: 1,
		ChangeBatch: []*remote.StateChange{
			{
				Direction:   remote.Direction_FORWARD,
				BlockHeight: 3,
				BlockHash:   gointerfaces.ConvertHashToH256([32]byte{2}),
				Changes: []*remote.AccountChange{{
					Action:  remote.Action_UPSERT,
					Address: gointerfaces.ConvertAddressToH160(k1),
					Data:    []byte{4},
				}},
			},
		},
	})
	fmt.Printf("-----5\n")

	res7, res8 := get(k1, txID5), get(k2, txID5) // will see View of transaction 3, even if notification has not enough changes

	wg.Add(1)
	go func() {
		defer wg.Done()
		for i := range res7 {
			require.Equal([]byte{4}, <-res7[i])
		}
		for i := range res8 {
			require.Equal([]byte{42}, <-res8[i])
		}
		fmt.Printf("done4: \n")
	}()
	err := db.View(context.Background(), func(tx kv.Tx) error {
		_, err := AssertCheckValues(context.Background(), tx, c)
		require.NoError(err)
		return nil
	})
	require.NoError(err)

	wg.Wait()
}

func TestCode(t *testing.T) {
	require, ctx := require.New(t), context.Background()
	c := New(DefaultCoherentConfig)
	db := memdb.NewTestDB(t)
	k1, k2 := [20]byte{1}, [20]byte{2}

	_ = db.Update(ctx, func(tx kv.RwTx) error {
		_ = tx.Put(kv.Code, k1[:], k2[:])
		cacheView, _ := c.View(ctx, tx)
		view := cacheView.(*CoherentView)

		v, err := c.GetCode(k1[:], tx, view.viewID)
		require.NoError(err)
		require.Equal(k2[:], v)

		v, err = c.GetCode(k1[:], tx, view.viewID)
		require.NoError(err)
		require.Equal(k2[:], v)

		//require.Equal(c.roots[c.latestViewID].cache.Len(), c.stateEvict.Len())
		return nil
	})
}