// Copyright 2013 The Go Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// This file tests types.Check by using it to
// typecheck the standard library.

package types

import (
	"flag"
	"fmt"
	"go/ast"
	"go/build"
	"go/parser"
	"go/scanner"
	"go/token"
	"io/ioutil"
	"path/filepath"
	"runtime"
	"testing"
	"time"
)

var verbose = flag.Bool("types.v", false, "verbose mode")

var (
	pkgCount int // number of packages processed
	start    = time.Now()
)

func TestStdlib(t *testing.T) {
	walkDirs(t, filepath.Join(runtime.GOROOT(), "src/pkg"))
	if *verbose {
		fmt.Println(pkgCount, "packages typechecked in", time.Since(start))
	}
}

// Package paths of excluded packages.
var excluded = map[string]bool{
	"builtin": true,
}

// typecheck typechecks the given package files.
func typecheck(t *testing.T, filenames []string) {
	fset := token.NewFileSet()

	// parse package files
	var files []*ast.File
	for _, filename := range filenames {
		file, err := parser.ParseFile(fset, filename, nil, parser.DeclarationErrors|parser.AllErrors)
		if err != nil {
			// the parser error may be a list of individual errors; report them all
			if list, ok := err.(scanner.ErrorList); ok {
				for _, err := range list {
					t.Error(err)
				}
				return
			}
			t.Error(err)
			return
		}

		if *verbose {
			if len(files) == 0 {
				fmt.Println("package", file.Name.Name)
			}
			fmt.Println("\t", filename)
		}

		files = append(files, file)
	}

	// typecheck package files
	ctxt := Context{
		Error: func(err error) { t.Error(err) },
	}
	ctxt.Check(fset, files)
	pkgCount++
}

// pkgfiles returns the list of package files for the given directory.
func pkgfiles(t *testing.T, dir string) []string {
	ctxt := build.Default
	ctxt.CgoEnabled = false
	pkg, err := ctxt.ImportDir(dir, 0)
	if err != nil {
		if _, nogo := err.(*build.NoGoError); !nogo {
			t.Error(err)
		}
		return nil
	}
	if excluded[pkg.ImportPath] {
		return nil
	}
	var filenames []string
	for _, name := range pkg.GoFiles {
		filenames = append(filenames, filepath.Join(pkg.Dir, name))
	}
	for _, name := range pkg.TestGoFiles {
		filenames = append(filenames, filepath.Join(pkg.Dir, name))
	}
	return filenames
}

// Note: Could use filepath.Walk instead of walkDirs but that wouldn't
//       necessarily be shorter or clearer after adding the code to
//       terminate early for -short tests.

func walkDirs(t *testing.T, dir string) {
	// limit run time for short tests
	if testing.Short() && time.Since(start) >= 750*time.Millisecond {
		return
	}

	fis, err := ioutil.ReadDir(dir)
	if err != nil {
		t.Error(err)
		return
	}

	// typecheck package in directory
	if files := pkgfiles(t, dir); files != nil {
		typecheck(t, files)
	}

	// traverse subdirectories, but don't walk into testdata
	for _, fi := range fis {
		if fi.IsDir() && fi.Name() != "testdata" {
			walkDirs(t, filepath.Join(dir, fi.Name()))
		}
	}
}