/*
   Copyright 2022 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 bptree

import (
	"fmt"
)

type Stats struct {
	ExposedCount  uint
	RehashedCount uint
	CreatedCount  uint
	UpdatedCount  uint
	DeletedCount  uint
	OpeningHashes uint
	ClosingHashes uint
}

type Tree23 struct {
	root *Node23
}

func NewEmptyTree23() *Tree23 {
	return &Tree23{}
}

func NewTree23(kvItems KeyValues) *Tree23 {
	tree := new(Tree23).Upsert(kvItems)
	tree.reset()
	return tree
}

func (t *Tree23) String() string {
	return fmt.Sprintf("root={keys=%v #children=%d} size=%d", deref(t.root.keys), t.root.childrenCount(), t.Size())
}

func (t *Tree23) Size() int {
	count := 0
	t.WalkPostOrder(func(n *Node23) interface{} { count++; return nil })
	return count
}

func (t *Tree23) RootHash() []byte {
	if t.root == nil {
		return []byte{}
	}
	return t.root.hashNode()
}

func (t *Tree23) IsValid() (bool, error) {
	if t.root == nil {
		return true, nil
	}
	// Last leaf must have sentinel next key
	if lastLeaf := t.root.lastLeaf(); lastLeaf.keyCount() > 0 && lastLeaf.nextKey() != nil {
		return false, fmt.Errorf("no sentinel next key in last leaf %d", &lastLeaf)
	}
	return t.root.isValid()
}

func (t *Tree23) Graph(filename string, debug bool) {
	graph := NewGraph(t.root)
	graph.saveDot(filename, debug)
}

func (t *Tree23) GraphAndPicture(filename string) error {
	graph := NewGraph(t.root)
	return graph.saveDotAndPicture(filename, false)
}

func (t *Tree23) GraphAndPictureDebug(filename string) error {
	graph := NewGraph(t.root)
	return graph.saveDotAndPicture(filename, true)
}

func (t *Tree23) Height() int {
	if t.root == nil {
		return 0
	}
	return t.root.height()
}

func (t *Tree23) KeysInLevelOrder() []Felt {
	if t.root == nil {
		return []Felt{}
	}
	return t.root.keysInLevelOrder()
}

func (t *Tree23) WalkPostOrder(w Walker) []interface{} {
	if t.root == nil {
		return make([]interface{}, 0)
	}
	return t.root.walkPostOrder(w)
}

func (t *Tree23) WalkKeysPostOrder() []Felt {
	keyPointers := make([]*Felt, 0)
	t.WalkPostOrder(func(n *Node23) interface{} {
		if n.isLeaf && n.keyCount() > 0 {
			keyPointers = append(keyPointers, n.keys[:len(n.keys)-1]...)
		}
		return nil
	})
	keys := deref(keyPointers)
	return keys
}

func (t *Tree23) Upsert(kvItems KeyValues) *Tree23 {
	return t.UpsertWithStats(kvItems, &Stats{})
}

func (t *Tree23) UpsertWithStats(kvItems KeyValues, stats *Stats) *Tree23 {
	promoted, _, intermediateKeys := upsert(t.root, kvItems, stats)
	ensure(len(promoted) > 0, "nodes length is zero")
	if len(promoted) == 1 {
		t.root = promoted[0]
	} else {
		t.root = promote(promoted, intermediateKeys, stats)
	}
	stats.RehashedCount, stats.ClosingHashes = t.countUpsertRehashedNodes()
	return t
}

func (t *Tree23) Delete(keyToDelete []Felt) *Tree23 {
	return t.DeleteWithStats(keyToDelete, &Stats{})
}

func (t *Tree23) DeleteWithStats(keysToDelete []Felt, stats *Stats) *Tree23 {
	newRoot, nextKey, intermediateKeys := del(t.root, keysToDelete, stats)
	t.root, _ = demote(newRoot, nextKey, intermediateKeys, stats)
	stats.RehashedCount, stats.ClosingHashes = t.countDeleteRehashedNodes()
	return t
}

func (t *Tree23) countUpsertRehashedNodes() (rehashedCount uint, closingHashes uint) {
	t.WalkPostOrder(func(n *Node23) interface{} {
		if n.exposed {
			rehashedCount++
			closingHashes += n.howManyHashes()
		}
		return nil
	})
	return rehashedCount, closingHashes
}

func (t *Tree23) countDeleteRehashedNodes() (rehashedCount uint, closingHashes uint) {
	t.WalkPostOrder(func(n *Node23) interface{} {
		if n.updated {
			rehashedCount++
			closingHashes += n.howManyHashes()
		}
		return nil
	})
	return rehashedCount, closingHashes
}

func (t *Tree23) reset() {
	if t.root == nil {
		return
	}
	t.root.reset()
}