package merkle

import "testing"

import (
    "os"
    "bytes"
    "math/rand"
    "encoding/binary"
)


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 randstr(length int) String {
    if urandom, err := os.Open("/dev/urandom"); err != nil {
        panic(err)
    } else {
        slice := make([]byte, length)
        if _, err := urandom.Read(slice); err != nil {
            panic(err)
        }
        urandom.Close()
        return String(slice)
    }
    panic("unreachable")
}

func TestImmutableAvlPutHasGetRemove(t *testing.T) {

    type record struct {
        key String
        value String
    }

    records := make([]*record, 400)
    var tree *IAVLNode
    var err error
    var val interface{}
    var updated bool

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

    for i := range records {
        r := ranrec()
        records[i] = r
        tree, updated = tree.Put(r.key, String(""))
        if updated {
            t.Error("should have not been updated")
        }
        tree, updated = tree.Put(r.key, r.value)
        if !updated {
            t.Error("should have been updated")
        }
        if tree.Size() != (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")
        }
        if has := tree.Has(randstr(12)); has {
            t.Error("Table has extra key")
        }
        if val, err := tree.Get(r.key); err != nil {
            t.Error(err, val.(String), r.value)
        } else if !(val.(String)).Equals(r.value) {
            t.Error("wrong value")
        }
    }

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


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

    type record struct {
        key String
        value String
    }

    records := make([]*record, 100)

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

    for i := range records {
        records[i] = ranrec()
    }

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


func TestTraversals(t *testing.T) {
    var data []int = []int{
        1, 5, 7, 9, 12, 13, 17, 18, 19, 20,
    }
    var order []int = []int{
        6, 1, 8, 2, 4 , 9 , 5 , 7 , 0 , 3 ,
    }
    /*
    var preorder []int = []int {
        17, 7, 5, 1, 12, 9, 13, 19, 18, 20,
    }
    var postorder []int = []int {
        1, 5, 9, 13, 12, 7, 18, 20, 19, 17,
    }
    */

    test := func(T Tree) {
        t.Logf("%T", T)
        for j := range order {
            if err := T.Put(Int(data[order[j]]), order[j]); err != nil {
                t.Error(err)
            }
        }

        j := 0
        for
          tn, next := Iterator(T.Root())();
          next != nil;
          tn, next = next () {
            if int(tn.Key().(Int)) != data[j] {
                t.Error("key in wrong spot in-order")
            }
            j += 1
        }

        /*
        j = 0
        for tn, next := tree.TraverseTreePreOrder(T.Root())(); next != nil; tn, next = next () {
            if int(tn.Key().(Int)) != preorder[j] {
                t.Error("key in wrong spot pre-order")
            }
            j += 1
        }

        j = 0
        for tn, next := tree.TraverseTreePostOrder(T.Root())(); next != nil; tn, next = next () {
            if int(tn.Key().(Int)) != postorder[j] {
                t.Error("key in wrong spot post-order")
            }
            j += 1
        }
        */
    }
    test(NewIAVLTree())
}