package docbuf

import (
	"testing"
	"fmt"
)

func docu(ctr *int) string {
	// we add a new line to try to trick the docbuf
	// into thinking there is an extra doc here.
	// but there isnt one.
	s := fmt.Sprintf("%d\n", *ctr)
	(*ctr) += 1

	return s
}

func TestPushPop(t *testing.T) {
	docCtr := 1

	backingStore := NewReadWriteSeekString()
	buf, e := NewDocumentBuffer(3, &backingStore)
	if e != nil {
		t.Fatalf("error making documentbuffer: %e", e)
	}

	// does push add 1 to cache
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 1 {
		t.Fatalf("error pushing: %e", err)
	}

	// does push past cache demote first document
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 2 {
		t.Fatalf("error pushing: %e", err)
	}
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 3 {
		t.Fatalf("error pushing: %e", err)
	}
	if err := buf.Push(docu(&docCtr)); err != nil || backingStore.Cursor() == 0 {
		t.Fatalf("error pushing: %e", err)
	}

	if backingStore.Contents() != "MQo=" {
		t.Fatalf("expected oldest doc to be in store, got %s",
			backingStore.Contents())
	}

	// does pop promote document from cache
	doc, err := buf.Pop()
	if err != nil || doc != "4\n" {
		t.Fatalf("did not get expected doc from cache: %s (%e)", doc, err)
	}
	if buf.Cached() != 3 {
		t.Fatalf("doc buffer did not promote: %d", buf.Cached())
	}

	// does pop past empty throw the right error
	doc, err = buf.Pop()
	if err != nil || doc != "3\n" {
		t.Fatalf("did not get expected doc from cache: %s (%e)", doc, err)
	}
	doc, err = buf.Pop()
	if err != nil || doc != "2\n" {
		t.Fatalf("did not get expected doc from cache: %s (%e)", doc, err)
	}
	doc, err = buf.Pop()
	if err != nil || doc != "1\n" {
		t.Logf("bs: %s", backingStore.Contents())
		t.Fatalf("did not get expected doc from cache: %s (%e)", doc, err)
	}
	doc, err = buf.Pop()
	if err == nil || 
	   doc != "" || 
	   err.Error() != "Can't pop from empty buffer" {
		t.Fatalf("did not get expected doc from cache: %s", doc)
	}
}

func TestRemove(t *testing.T) {
	docCtr := 1
	backingStore := NewReadWriteSeekString()
	buf, e := NewDocumentBuffer(3, &backingStore)
	if e != nil {
		t.Fatalf("error making documentbuffer: %e", e)
	}

	// setup test data
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 1 {
		t.Fatalf("error pushing: %e", err)
	}
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 2 {
		t.Fatalf("error pushing: %e", err)
	}
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 3 {
		t.Fatalf("error pushing: %e", err)
	}
	if err := buf.Push(docu(&docCtr)); err != nil || 
	   buf.Cached() != 3 || backingStore.Contents() != "MQo=" {
		t.Fatalf("error pushing: %e", err)
	}

	// tests
	docs, err := buf.Remove(2)
	if err != nil ||
	   len(docs) != 2 ||
	   docs[0] != "4\n" ||
	   docs[1] != "3\n" ||
	   buf.Cached() != 2 {
		t.Fatalf("error removing: %e", err)
	}

	for range 5 {
		if err := buf.Push(docu(&docCtr)); err != nil {
			t.Fatalf("error pushing: %e", err)
		}
	}
	
	docs, err = buf.Remove(4)
	if err != nil ||
	   len(docs) != 4 ||
	   docs[0] != "9\n" ||
	   docs[1] != "8\n" ||
	   docs[2] != "7\n" ||
	   docs[3] != "6\n" ||
	   buf.Cached() != 3 {
		t.Fatalf("error removing: %e", err)
	}

	docs, err = buf.Remove(3)
	if err != nil ||
	   len(docs) != 3 ||
	   docs[0] != "5\n" ||
	   docs[1] != "2\n" ||
	   docs[2] != "1\n" ||
	   buf.Cached() != 0 {
		t.Fatalf("error removing: %e", err)
	}
}

func TestFlush(t *testing.T) {
	docCtr := 1
	expectedDoc := "MQo=\nMgo=\nMwo=\nNAo="
	backingStore := NewReadWriteSeekString()
	buf, e := NewDocumentBuffer(3, &backingStore)
	if e != nil {
		t.Fatalf("error making documentbuffer: %e", e)
	}

	// setup test data
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 1 {
		t.Fatalf("error pushing: %e", err)
	}
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 2 {
		t.Fatalf("error pushing: %e", err)
	}
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 3 {
		t.Fatalf("error pushing: %e", err)
	}
	if err := buf.Push(docu(&docCtr)); err != nil || 
	   buf.Cached() != 3 || backingStore.Contents() == "Nao=\n" {
		t.Fatalf("error pushing: %e", err)
	}

	// test
	if err := buf.Flush(); err != nil {
		t.Fatalf("error flushing buffer: %e", err)
	}

	if backingStore.Contents() != expectedDoc {
		t.Fatalf("did not get expected document: %s", backingStore.Contents())
	}
}

func TestPeek(t *testing.T) {
	docCtr := 1
	backingStore := NewReadWriteSeekString()
	buf, e := NewDocumentBuffer(3, &backingStore)
	if e != nil {
		t.Fatalf("error making documentbuffer: %e", e)
	}

	// setup test data
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 1 {
		t.Fatalf("error pushing: %e", err)
	}

	// test
	if d, e := buf.Peek(); e != nil ||
	   d != "1\n" ||
	   buf.Cached() != 1 {
		t.Fatalf("error peeking: %e", e)
	   }
}

func TestRead(t *testing.T) {
	docCtr := 1
	backingStore := NewReadWriteSeekString()
	buf, e := NewDocumentBuffer(3, &backingStore)
	if e != nil {
		t.Fatalf("error making documentbuffer: %e", e)
	}

	// setup test data
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 1 {
		t.Fatalf("error pushing: %e", err)
	}
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 2 {
		t.Fatalf("error pushing: %e", err)
	}
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 3 {
		t.Fatalf("error pushing: %e", err)
	}
	if err := buf.Push(docu(&docCtr)); err != nil || 
	   buf.Cached() != 3 || backingStore.Contents() != "MQo=" {
		t.Fatalf("error pushing: %e", err)
	}

	// test
	if docs, err := buf.Read(4); err != nil ||
	   len(docs) != 4 ||
	   docs[0] != "4\n" ||
	   docs[1] != "3\n" ||
	   docs[2] != "2\n" ||
	   docs[3] != "1\n" ||
	   buf.Cached() != 3 ||
	   backingStore.Contents() != "MQo=" {
		t.Fatalf("error reading: %e", err)
	}
}

func TestClose(t *testing.T) {
	// do pushes and a remove then Close. assure no error
	// is the int return where I can truncate?
	docCtr := 1
	backingStore := NewReadWriteSeekString()
	buf, e := NewDocumentBuffer(3, &backingStore)
	if e != nil {
		t.Fatalf("error making documentbuffer: %e", e)
	}

	// setup test data
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 1 {
		t.Fatalf("error pushing: %e", err)
	}
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 2 {
		t.Fatalf("error pushing: %e", err)
	}
	if err := buf.Push(docu(&docCtr)); err != nil || buf.Cached() != 3 {
		t.Fatalf("error pushing: %e", err)
	}
	if err := buf.Push(docu(&docCtr)); err != nil || 
	   buf.Cached() != 3 || backingStore.Contents() != "MQo=" {
		t.Fatalf("error pushing: %e", err)
	}

	for range 5 {
		if err := buf.Push(docu(&docCtr)); err != nil {
			t.Fatalf("error pushing: %e", err)
		}
	}
	
	docs, err := buf.Remove(4)
	if err != nil ||
	   len(docs) != 4 ||
	   buf.Cached() != 3 {
		t.Fatalf("error removing: %e", err)
	}

	expectedDoc := "MQo=\nMgo=\nMwo=\nNAo=\nNQo=\nNgo="
	idx, err := buf.Close()
	if err != nil ||
	   idx != 24 ||
	   buf.Cached() != 0 ||
	   backingStore.Contents() != expectedDoc {
		t.Fatalf("error closing: %e", err)
	}
}

func TestInitialize(t *testing.T) {
	backingStore := NewReadWriteSeekString()
	backingStore.Write([]byte("MQo=\nMgo=\nMwo=\nNAo=\nNQo=\nNgo="))
	buf, e := NewDocumentBuffer(3, &backingStore)
	if e != nil {
		t.Fatalf("error making documentbuffer: %e", e)
	}
	
	// test cached
	if buf.Cached() != 3 {
		t.Fatalf("expected 3 docs in cache")
	}

	// read all docs
	docs, err := buf.Read(6)
	if err != nil ||
	   len(docs) != 6 ||
	   docs[0] != "6\n" ||
	   docs[1] != "5\n" ||
	   docs[2] != "4\n" ||
	   docs[3] != "3\n" ||
	   docs[4] != "2\n" ||
	   docs[5] != "1\n" {
		t.Fatalf("error reading: %e", err)
	}
}

func TestApply(t *testing.T) {
	backingStore := NewReadWriteSeekString()
	backingStore.Write([]byte("MQo=\nMgo=\nMwo=\nNAo=\nNQo=\nNgo="))
	buf, e := NewDocumentBuffer(3, &backingStore)
	if e != nil {
		t.Fatalf("error making documentbuffer: %e", e)
	}
	
	// test cached
	if buf.Cached() != 3 {
		t.Fatalf("expected 3 docs in cache")
	}

	count := 0
	if err := buf.Apply(func(doc string) bool {
		count += 1
		return true
	}); err != nil || count != 6 {
		t.Fatalf("error applying: %e", err)
	}

	count = 0
	if err := buf.Apply(func(doc string) bool {
		if doc == "2\n" {
			return false
		}
		count += 1
		return true
	}); err != nil || count != 4 {
		t.Fatalf("error applying: %e", err)
	}
}