package merkle

import (
    "testing"
    "fmt"
    "os"
    "bytes"
    "math/rand"
    "encoding/binary"
    "github.com/tendermint/tendermint/db"
    "crypto/sha256"
    "runtime"
)

func init() {
    if urandom, err := os.Open("/dev/urandom"); err != nil {
        return
    } else {
        buf := make([]byte, 8)
        if _, err := urandom.Read(buf); err == nil {
            buf_reader := bytes.NewReader(buf)
            if seed, err := binary.ReadVarint(buf_reader); err == nil {
                rand.Seed(seed)
            }
        }
        urandom.Close()
    }
}

func TestUnit(t *testing.T) {

    // Convenience for a new node
    N := func(l, r interface{}) *IAVLNode {
        var left, right *IAVLNode
        if _, ok := l.(*IAVLNode); ok {
            left = l.(*IAVLNode)
        } else {
            left = NewIAVLNode(Int32(l.(int)), nil)
        }
        if _, ok := r.(*IAVLNode); ok {
            right = r.(*IAVLNode)
        } else {
            right = NewIAVLNode(Int32(r.(int)), nil)
        }

        n := &IAVLNode{
            key:    right.lmd(nil).key,
            left:   left,
            right:  right,
        }
        n.calcHeightAndSize(nil)
        n.Hash()
        return n
    }

    // Convenience for simple printing of keys & tree structure
    var P func(*IAVLNode) string
    P = func(n *IAVLNode) string {
        if n.height == 0 {
            return fmt.Sprintf("%v", n.key)
        } else {
            return fmt.Sprintf("(%v %v)", P(n.left), P(n.right))
        }
    }

    expectHash := func(n2 *IAVLNode, hashCount uint64) {
        // ensure number of new hash calculations is as expected.
        hash, count := n2.Hash()
        if count != hashCount {
            t.Fatalf("Expected %v new hashes, got %v", hashCount, count)
        }
        // nuke hashes and reconstruct hash, ensure it's the same.
        (&IAVLTree{root:n2}).Traverse(func(node Node) bool {
            node.(*IAVLNode).hash = nil
            return false
        })
        // ensure that the new hash after nuking is the same as the old.
        newHash, _ := n2.Hash()
        if bytes.Compare(hash, newHash) != 0 {
            t.Fatalf("Expected hash %v but got %v after nuking", hash, newHash)
        }
    }

    expectPut := func(n *IAVLNode, i int, repr string, hashCount uint64) {
        n2, updated := n.put(nil, Int32(i), nil)
        // ensure node was added & structure is as expected.
        if updated == true || P(n2) != repr {
            t.Fatalf("Adding %v to %v:\nExpected         %v\nUnexpectedly got %v updated:%v",
                i, P(n), repr, P(n2), updated)
        }
        // ensure hash calculation requirements
        expectHash(n2, hashCount)
    }

    expectRemove := func(n *IAVLNode, i int, repr string, hashCount uint64) {
        n2, _, value, err := n.remove(nil, Int32(i))
        // ensure node was added & structure is as expected.
        if value != nil || err != nil || P(n2) != repr {
            t.Fatalf("Removing %v from %v:\nExpected         %v\nUnexpectedly got %v value:%v err:%v",
                i, P(n), repr, P(n2), value, err)
        }
        // ensure hash calculation requirements
        expectHash(n2, hashCount)
    }

    //////// Test Put cases:

    // Case 1:
    n1 := N(4, 20)

    expectPut(n1, 8, "((4 8) 20)", 3)
    expectPut(n1, 25, "(4 (20 25))", 3)

    n2 := N(4, N(20, 25))

    expectPut(n2, 8, "((4 8) (20 25))", 3)
    expectPut(n2, 30, "((4 20) (25 30))", 4)

    n3 := N(N(1, 2), 6)

    expectPut(n3, 4, "((1 2) (4 6))", 4)
    expectPut(n3, 8, "((1 2) (6 8))", 3)

    n4 := N(N(1, 2), N(N(5, 6), N(7, 9)))

    expectPut(n4, 8, "(((1 2) (5 6)) ((7 8) 9))", 5)
    expectPut(n4, 10, "(((1 2) (5 6)) (7 (9 10)))", 5)

    //////// Test Remove cases:

    n10 := N(N(1, 2), 3)

    expectRemove(n10, 2, "(1 3)", 1)
    expectRemove(n10, 3, "(1 2)", 0)

    n11 := N(N(N(1, 2), 3), N(4, 5))

    expectRemove(n11, 4, "((1 2) (3 5))", 2)
    expectRemove(n11, 3, "((1 2) (4 5))", 1)

}

func TestIntegration(t *testing.T) {

    type record struct {
        key String
        value String
    }

    records := make([]*record, 400)
    var tree *IAVLTree = NewIAVLTree(nil)
    var err error
    var val Value
    var updated bool

    randomRecord := func() *record {
        return &record{ randstr(20), randstr(20) }
    }

    for i := range records {
        r := randomRecord()
        records[i] = r
        //t.Log("New record", r)
        //PrintIAVLNode(tree.root)
        updated = tree.Put(r.key, String(""))
        if updated {
            t.Error("should have not been updated")
        }
        updated = tree.Put(r.key, r.value)
        if !updated {
            t.Error("should have been updated")
        }
        if tree.Size() != uint64(i+1) {
            t.Error("size was wrong", tree.Size(), i+1)
        }
    }

    for _, r := range records {
        if has := tree.Has(r.key); !has {
            t.Error("Missing key", r.key)
        }
        if has := tree.Has(randstr(12)); has {
            t.Error("Table has extra key")
        }
        if val := tree.Get(r.key); !(val.(String)).Equals(r.value) {
            t.Error("wrong value")
        }
    }

    for i, x := range records {
        if val, err = tree.Remove(x.key); err != nil {
            t.Error(err)
        } else if !(val.(String)).Equals(x.value) {
            t.Error("wrong value")
        }
        for _, r := range records[i+1:] {
            if has := tree.Has(r.key); !has {
                t.Error("Missing key", r.key)
            }
            if has := tree.Has(randstr(12)); has {
                t.Error("Table has extra key")
            }
            if val := tree.Get(r.key); !(val.(String)).Equals(r.value) {
                t.Error("wrong value")
            }
        }
        if tree.Size() != uint64(len(records) - (i+1)) {
            t.Error("size was wrong", tree.Size(), (len(records) - (i+1)))
        }
    }
}

func TestPersistence(t *testing.T) {
    db := db.NewMemDB()

    // Create some random key value pairs
    records := make(map[String]String)
    for i:=0; i<10000; i++ {
        records[String(randstr(20))] = String(randstr(20))
    }

    // Construct some tree and save it
    t1 := NewIAVLTree(db)
    for key, value := range records {
        t1.Put(key, value)
    }
    t1.Save()

    hash, _ := t1.Hash()

    // Load a tree
    t2 := NewIAVLTreeFromHash(db, hash)
    for key, value := range records {
        t2value := t2.Get(key)
        if !t2value.Equals(value) {
            t.Fatalf("Invalid value. Expected %v, got %v", value, t2value)
        }
    }
}

func BenchmarkHash(b *testing.B) {
    b.StopTimer()

    s := randstr(128)

    b.StartTimer()
    for i := 0; i < b.N; i++ {
        hasher := sha256.New()
        hasher.Write([]byte(s))
        hasher.Sum(nil)
    }
}

func BenchmarkImmutableAvlTree(b *testing.B) {
    b.StopTimer()

    type record struct {
        key String
        value String
    }

    randomRecord := func() *record {
        return &record{ randstr(32), randstr(32) }
    }

    t := NewIAVLTree(nil)
    for i:=0; i<1000000; i++ {
        r := randomRecord()
        t.Put(r.key, r.value)
    }

    fmt.Println("ok, starting")

    runtime.GC()

    b.StartTimer()
    for i := 0; i < b.N; i++ {
        r := randomRecord()
        t.Put(r.key, r.value)
        t.Remove(r.key)
    }
}