// Copyright 2011 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.

package api

import (
	"flag"
	"fmt"
	"go/build"
	"internal/testenv"
	"os"
	"path/filepath"
	"sort"
	"strings"
	"sync"
	"testing"
)

var flagCheck = flag.Bool("check", false, "run API checks")

func TestMain(m *testing.M) {
	if !testenv.HasExec() {
		os.Stdout.WriteString("skipping test: platform cannot exec")
		os.Exit(0)
	}
	if !testenv.HasGoBuild() {
		os.Stdout.WriteString("skipping test: platform cannot 'go build' to import std packages")
		os.Exit(0)
	}

	flag.Parse()
	for _, c := range contexts {
		c.Compiler = build.Default.Compiler
	}
	build.Default.GOROOT = testenv.GOROOT(nil)

	// Warm up the import cache in parallel.
	var wg sync.WaitGroup
	for _, context := range contexts {
		context := context
		wg.Add(1)
		go func() {
			defer wg.Done()
			_ = NewWalker(context, filepath.Join(testenv.GOROOT(nil), "src"))
		}()
	}
	wg.Wait()

	os.Exit(m.Run())
}

var (
	updateGolden = flag.Bool("updategolden", false, "update golden files")
)

func TestGolden(t *testing.T) {
	if *flagCheck {
		// slow, not worth repeating in -check
		t.Skip("skipping with -check set")
	}
	td, err := os.Open("testdata/src/pkg")
	if err != nil {
		t.Fatal(err)
	}
	fis, err := td.Readdir(0)
	if err != nil {
		t.Fatal(err)
	}
	for _, fi := range fis {
		if !fi.IsDir() {
			continue
		}

		// TODO(gri) remove extra pkg directory eventually
		goldenFile := filepath.Join("testdata", "src", "pkg", fi.Name(), "golden.txt")
		w := NewWalker(nil, "testdata/src/pkg")
		pkg, _ := w.import_(fi.Name())
		w.export(pkg)

		if *updateGolden {
			os.Remove(goldenFile)
			f, err := os.Create(goldenFile)
			if err != nil {
				t.Fatal(err)
			}
			for _, feat := range w.Features() {
				fmt.Fprintf(f, "%s\n", feat)
			}
			f.Close()
		}

		bs, err := os.ReadFile(goldenFile)
		if err != nil {
			t.Fatalf("opening golden.txt for package %q: %v", fi.Name(), err)
		}
		wanted := strings.Split(string(bs), "\n")
		sort.Strings(wanted)
		for _, feature := range wanted {
			if feature == "" {
				continue
			}
			_, ok := w.features[feature]
			if !ok {
				t.Errorf("package %s: missing feature %q", fi.Name(), feature)
			}
			delete(w.features, feature)
		}

		for _, feature := range w.Features() {
			t.Errorf("package %s: extra feature not in golden file: %q", fi.Name(), feature)
		}
	}
}

func TestCompareAPI(t *testing.T) {
	tests := []struct {
		name                                    string
		features, required, optional, exception []string
		ok                                      bool   // want
		out                                     string // want
	}{
		{
			name:     "feature added",
			features: []string{"A", "B", "C", "D", "E", "F"},
			required: []string{"B", "D"},
			ok:       true,
			out:      "+A\n+C\n+E\n+F\n",
		},
		{
			name:     "feature removed",
			features: []string{"C", "A"},
			required: []string{"A", "B", "C"},
			ok:       false,
			out:      "-B\n",
		},
		{
			name:     "feature added then removed",
			features: []string{"A", "C"},
			optional: []string{"B"},
			required: []string{"A", "C"},
			ok:       true,
			out:      "±B\n",
		},
		{
			name:      "exception removal",
			required:  []string{"A", "B", "C"},
			features:  []string{"A", "C"},
			exception: []string{"B"},
			ok:        true,
			out:       "",
		},
		{
			// https://golang.org/issue/4303
			name: "contexts reconverging",
			required: []string{
				"A",
				"pkg syscall (darwin-amd64), type RawSockaddrInet6 struct",
			},
			features: []string{
				"A",
				"pkg syscall, type RawSockaddrInet6 struct",
			},
			ok:  true,
			out: "+pkg syscall, type RawSockaddrInet6 struct\n",
		},
	}
	for _, tt := range tests {
		buf := new(strings.Builder)
		gotok := compareAPI(buf, tt.features, tt.required, tt.optional, tt.exception, true)
		if gotok != tt.ok {
			t.Errorf("%s: ok = %v; want %v", tt.name, gotok, tt.ok)
		}
		if got := buf.String(); got != tt.out {
			t.Errorf("%s: output differs\nGOT:\n%s\nWANT:\n%s", tt.name, got, tt.out)
		}
	}
}

func TestSkipInternal(t *testing.T) {
	tests := []struct {
		pkg  string
		want bool
	}{
		{"net/http", true},
		{"net/http/internal-foo", true},
		{"net/http/internal", false},
		{"net/http/internal/bar", false},
		{"internal/foo", false},
		{"internal", false},
	}
	for _, tt := range tests {
		got := !internalPkg.MatchString(tt.pkg)
		if got != tt.want {
			t.Errorf("%s is internal = %v; want %v", tt.pkg, got, tt.want)
		}
	}
}

func BenchmarkAll(b *testing.B) {
	for i := 0; i < b.N; i++ {
		for _, context := range contexts {
			w := NewWalker(context, filepath.Join(testenv.GOROOT(b), "src"))
			for _, name := range w.stdPackages {
				pkg, _ := w.import_(name)
				w.export(pkg)
			}
			w.Features()
		}
	}
}

func TestIssue21181(t *testing.T) {
	if *flagCheck {
		// slow, not worth repeating in -check
		t.Skip("skipping with -check set")
	}
	for _, context := range contexts {
		w := NewWalker(context, "testdata/src/issue21181")
		pkg, err := w.import_("p")
		if err != nil {
			t.Fatalf("%s: (%s-%s) %s %v", err, context.GOOS, context.GOARCH,
				pkg.Name(), w.imported)
		}
		w.export(pkg)
	}
}

func TestIssue29837(t *testing.T) {
	if *flagCheck {
		// slow, not worth repeating in -check
		t.Skip("skipping with -check set")
	}
	for _, context := range contexts {
		w := NewWalker(context, "testdata/src/issue29837")
		_, err := w.ImportFrom("p", "", 0)
		if _, nogo := err.(*build.NoGoError); !nogo {
			t.Errorf("expected *build.NoGoError, got %T", err)
		}
	}
}

func TestIssue41358(t *testing.T) {
	if *flagCheck {
		// slow, not worth repeating in -check
		t.Skip("skipping with -check set")
	}
	context := new(build.Context)
	*context = build.Default
	context.Dir = filepath.Join(testenv.GOROOT(t), "src")

	w := NewWalker(context, context.Dir)
	for _, pkg := range w.stdPackages {
		if strings.HasPrefix(pkg, "vendor/") || strings.HasPrefix(pkg, "golang.org/x/") {
			t.Fatalf("stdPackages contains unexpected package %s", pkg)
		}
	}
}

func TestCheck(t *testing.T) {
	if !*flagCheck {
		t.Skip("-check not specified")
	}
	Check(t)
}