package cgo

import (
	"bytes"
	"go/format"
	"go/token"
	"strings"
	"testing"
)

func TestParseConst(t *testing.T) {
	// Test converting a C constant to a Go constant.
	for _, tc := range []struct {
		C  string
		Go string
	}{
		{`5`, `5`},
		{`(5)`, `(5)`},
		{`(((5)))`, `(5)`},
		{`)`, `error: 1:1: unexpected token )`},
		{`5)`, `error: 1:2: unexpected token ), expected end of expression`},
		{"  \t)", `error: 1:4: unexpected token )`},
		{`5.8f`, `5.8`},
		{`foo`, `C.foo`},
		{``, `error: 1:1: empty constant`}, // empty constants not allowed in Go
		{`"foo"`, `"foo"`},
		{`"a\\n"`, `"a\\n"`},
		{`"a\n"`, `"a\n"`},
		{`"a\""`, `"a\""`},
		{`'a'`, `'a'`},
		{`0b10`, `0b10`},
		{`0x1234_5678`, `0x1234_5678`},
		{`5 5`, `error: 1:3: unexpected token INT, expected end of expression`}, // test for a bugfix
	} {
		fset := token.NewFileSet()
		startPos := fset.AddFile("", -1, 1000).Pos(0)
		expr, err := parseConst(startPos, fset, tc.C)
		s := "<invalid>"
		if err != nil {
			if !strings.HasPrefix(tc.Go, "error: ") {
				t.Errorf("expected value %#v for C constant %#v but got error %#v", tc.Go, tc.C, err.Error())
				continue
			}
			s = "error: " + err.Error()
		} else if expr != nil {
			// Serialize the Go constant to a string, for more readable test
			// cases.
			buf := &bytes.Buffer{}
			err := format.Node(buf, fset, expr)
			if err != nil {
				t.Errorf("could not format expr from C constant %#v: %v", tc.C, err)
				continue
			}
			s = buf.String()
		}
		if s != tc.Go {
			t.Errorf("C constant %#v was parsed to %#v while expecting %#v", tc.C, s, tc.Go)
		}
	}
}