// Copyright 2018 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 (
	"go/build"
	"runtime"
	"testing"

	"golang.org/x/website/internal/backport/osfs"
)

func TestParseVersionRow(t *testing.T) {
	tests := []struct {
		row  string
		want row
	}{
		{
			row: "# comment",
		},
		{
			row: "",
		},
		{
			row: "pkg archive/tar, type Writer struct",
			want: row{
				pkg:  "archive/tar",
				kind: "type",
				name: "Writer",
			},
		},
		{
			row: "pkg archive/tar, type Header struct, AccessTime time.Time",
			want: row{
				pkg:        "archive/tar",
				kind:       "field",
				structName: "Header",
				name:       "AccessTime",
			},
		},
		{
			row: "pkg archive/tar, method (*Reader) Read([]uint8) (int, error)",
			want: row{
				pkg:  "archive/tar",
				kind: "method",
				name: "Read",
				recv: "*Reader",
			},
		},
		{
			row: "pkg archive/zip, func FileInfoHeader(os.FileInfo) (*FileHeader, error)",
			want: row{
				pkg:  "archive/zip",
				kind: "func",
				name: "FileInfoHeader",
			},
		},
		{
			row: "pkg encoding/base32, method (Encoding) WithPadding(int32) *Encoding",
			want: row{
				pkg:  "encoding/base32",
				kind: "method",
				name: "WithPadding",
				recv: "Encoding",
			},
		},
	}

	for i, tt := range tests {
		got, ok := parseRow(tt.row)
		if !ok {
			got = row{}
		}
		if got != tt.want {
			t.Errorf("%d. parseRow(%q) = %+v; want %+v", i, tt.row, got, tt.want)
		}
	}
}

// hasTag checks whether a given release tag is contained in the current version
// of the go binary.
func hasTag(t string) bool {
	for _, v := range build.Default.ReleaseTags {
		if t == v {
			return true
		}
	}
	return false
}

func TestAPIVersion(t *testing.T) {
	av, err := Load(osfs.DirFS(runtime.GOROOT()))
	if err != nil {
		t.Fatal(err)
	}
	for _, tc := range []struct {
		kind     string
		pkg      string
		name     string
		receiver string
		want     string
	}{
		// Things that were added post-1.0 should appear
		{"func", "archive/tar", "FileInfoHeader", "", "1.1"},
		{"type", "bufio", "Scanner", "", "1.1"},
		{"method", "bufio", "WriteTo", "*Reader", "1.1"},

		{"func", "bytes", "LastIndexByte", "", "1.5"},
		{"type", "crypto", "Decrypter", "", "1.5"},
		{"method", "crypto/rsa", "Decrypt", "*PrivateKey", "1.5"},
		{"method", "debug/dwarf", "GoString", "Class", "1.5"},

		{"func", "os", "IsTimeout", "", "1.10"},
		{"type", "strings", "Builder", "", "1.10"},
		{"method", "strings", "WriteString", "*Builder", "1.10"},

		// Should get the earliest Go version when an identifier
		// was initially added, rather than a later version when
		// it may have been updated. See issue 44081.
		{"func", "os", "Chmod", "", ""},              // Go 1 era function, updated in Go 1.16.
		{"method", "os", "Readdir", "*File", ""},     // Go 1 era method, updated in Go 1.16.
		{"method", "os", "ReadDir", "*File", "1.16"}, // New to Go 1.16.

		// Things from package syscall should never appear
		{"func", "syscall", "FchFlags", "", ""},
		{"type", "syscall", "Inet4Pktinfo", "", ""},

		// Things added in Go 1 should never appear
		{"func", "archive/tar", "NewReader", "", ""},
		{"type", "archive/tar", "Header", "", ""},
		{"method", "archive/tar", "Next", "*Reader", ""},
	} {
		if tc.want != "" && !hasTag("go"+tc.want) {
			continue
		}
		if got := av.Func(tc.pkg, tc.kind, tc.receiver, tc.name); got != tc.want {
			t.Errorf(`sinceFunc(%q, %q, %q, %q) = %q; want %q`, tc.pkg, tc.kind, tc.receiver, tc.name, got, tc.want)
		}
	}
}