package sql

import (
	"bytes"
	"io"
	"testing"
)

func Test_stackEmpty(t *testing.T) {
	s := newStack()
	if !s.empty() {
		t.Fatal("new stack is not empty")
	}

	if s.peek() != rune(0) {
		t.Fatal("peek of empty stack does not return correct value")
	}
}

func Test_stackSingle(t *testing.T) {
	s := newStack()
	s.push('x')
	if s.empty() {
		t.Fatal("non-empty stack marked as empty")
	}

	if s.peek() != 'x' {
		t.Fatal("peek of stack with single entry does not return correct value")
	}

	if s.pop() != 'x' {
		t.Fatal("pop of stack with single entry does not return correct value")
	}

	if !s.empty() {
		t.Fatal("popped stack is not empty")
	}
}

func Test_stackMulti(t *testing.T) {
	s := newStack()
	s.push('x')
	s.push('y')
	s.push('z')

	if s.pop() != 'z' {
		t.Fatal("pop of 1st multi stack does not return correct value")
	}
	if s.pop() != 'y' {
		t.Fatal("pop of 2nd multi stack does not return correct value")
	}
	if s.pop() != 'x' {
		t.Fatal("pop of 3rd multi stack does not return correct value")
	}

	if !s.empty() {
		t.Fatal("popped mstack is not empty")
	}
}

func Test_ScannerNew(t *testing.T) {
	s := NewScanner(nil)
	if s == nil {
		t.Fatalf("failed to create basic Scanner")
	}
}

func Test_ScannerEmpty(t *testing.T) {
	r := bytes.NewBufferString("")
	s := NewScanner(r)

	_, err := s.Scan()
	if err != io.EOF {
		t.Fatal("Scan of empty string did not return EOF")
	}
}

func Test_ScannerSemi(t *testing.T) {
	r := bytes.NewBufferString(";")
	s := NewScanner(r)

	l, err := s.Scan()
	if err != nil {
		t.Fatal("Scan of single semicolon failed")
	}
	if l != ";" {
		t.Fatal("Scan of single semicolon returned incorrect value")
	}
	_, err = s.Scan()
	if err != io.EOF {
		t.Fatal("Scan of empty string after semicolon did not return EOF")
	}
}

func Test_ScannerSingleStatement(t *testing.T) {
	r := bytes.NewBufferString("SELECT * FROM foo;")
	s := NewScanner(r)

	l, err := s.Scan()
	if err != nil {
		t.Fatal("Scan of single statement failed")
	}
	if l != "SELECT * FROM foo;" {
		t.Fatal("Scan of single statement returned incorrect value")
	}
	_, err = s.Scan()
	if err != io.EOF {
		t.Fatal("Scan of empty string after statement did not return EOF")
	}
}

func Test_ScannerSingleStatementQuotes(t *testing.T) {
	r := bytes.NewBufferString(`SELECT * FROM "foo";`)
	s := NewScanner(r)

	l, err := s.Scan()
	if err != nil {
		t.Fatal("Scan of single statement failed")
	}
	if l != `SELECT * FROM "foo";` {
		t.Fatal("Scan of single statement returned incorrect value")
	}
	_, err = s.Scan()
	if err != io.EOF {
		t.Fatal("Scan of empty string after statement did not return EOF")
	}
}

func Test_ScannerSingleStatementQuotesEmbedded(t *testing.T) {
	r := bytes.NewBufferString(`SELECT * FROM ";SELECT * FROM '"foo"'";`)
	s := NewScanner(r)

	l, err := s.Scan()
	if err != nil {
		t.Fatal("Scan of single statement failed")
	}
	if l != `SELECT * FROM ";SELECT * FROM '"foo"'";` {
		t.Fatal("Scan of single statement returned incorrect value")
	}
	_, err = s.Scan()
	if err != io.EOF {
		t.Fatal("Scan of empty string after statement did not return EOF")
	}
}

func Test_ScannerMultiStatement(t *testing.T) {
	r := bytes.NewBufferString("SELECT * FROM foo;SELECT * FROM bar;")
	s := NewScanner(r)

	l, err := s.Scan()
	if err != nil {
		t.Fatal("Scan of multi statement failed")
	}
	if l != "SELECT * FROM foo;" {
		t.Fatal("Scan of first of multi statement returned incorrect value")
	}

	l, err = s.Scan()
	if err != nil {
		t.Fatal("Scan of multi statement failed")
	}
	if l != "SELECT * FROM bar;" {
		t.Fatal("Scan of second of multi statement returned incorrect value")
	}
}

func Test_ScannerMultiStatementQuotesEmbedded(t *testing.T) {
	r := bytes.NewBufferString(`SELECT * FROM "foo;barx";SELECT * FROM bar;`)
	s := NewScanner(r)

	l, err := s.Scan()
	if err != nil {
		t.Fatal("Scan of multi statement failed")
	}
	if l != `SELECT * FROM "foo;barx";` {
		t.Fatal("Scan of first of multi statement returned incorrect value")
	}

	l, err = s.Scan()
	if err != nil {
		t.Fatal("Scan of multi statement failed")
	}
	if l != "SELECT * FROM bar;" {
		t.Fatal("Scan of second of multi statement returned incorrect value")
	}
}

// XX I am missing this case: '"' ????