// Copyright 2019 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 fetch

import (
	"context"
	"errors"
	"io/fs"
	"testing"

	"github.com/google/go-cmp/cmp"
	"golang.org/x/pkgsite/internal"
	"golang.org/x/pkgsite/internal/derrors"
	"golang.org/x/pkgsite/internal/proxy/proxytest"
	"golang.org/x/pkgsite/internal/stdlib"
	"golang.org/x/pkgsite/internal/testenv"
)

func TestExtractReadme(t *testing.T) {
	testenv.MustHaveExecPath(t, "git")
	defer stdlib.WithTestData()()

	ctx := context.Background()

	for _, test := range []struct {
		name, modulePath, pkgPath, version string
		files                              map[string]string
		want                               *internal.Readme
	}{
		{
			name:       "README at root and README in unit and README in _",
			modulePath: stdlib.ModulePath,
			pkgPath:    "cmd/pprof",
			version:    "v1.12.5",
			want: &internal.Readme{
				Filepath: "cmd/pprof/README",
				Contents: "This directory is the copy of Google's pprof shipped as part of the Go distribution.\n",
			},
		},
		{
			name:       "directory start with _",
			modulePath: "github.com/my/module",
			pkgPath:    "github.com/my/module/_foo",
			version:    "v1.0.0",
			files: map[string]string{
				"_foo/README.md": "README",
			},
			want: nil,
		},
		{
			name:       "prefer README.md",
			modulePath: "github.com/my/module",
			pkgPath:    "github.com/my/module/foo",
			version:    "v1.0.0",
			files: map[string]string{
				"foo/README":    "README",
				"foo/README.md": "README",
			},
			want: &internal.Readme{
				Filepath: "foo/README.md",
				Contents: "README",
			},
		},
		{
			name:       "prefer readme.markdown",
			modulePath: "github.com/my/module",
			pkgPath:    "github.com/my/module/foo",
			version:    "v1.0.0",
			files: map[string]string{
				"foo/README.markdown": "README",
				"foo/readme.rst":      "README",
			},
			want: &internal.Readme{
				Filepath: "foo/README.markdown",
				Contents: "README",
			},
		},
		{
			name:       "no readme",
			modulePath: "emp.ty/module",
			version:    "v1.0.0",
			files:      map[string]string{},
		},
		{
			name:       "readme is a directory",
			modulePath: "github.com/my/module",
			version:    "v1.0.0",
			files: map[string]string{
				"foo/README/bar": "README",
			},
			want: nil,
		},
	} {
		t.Run(test.name, func(t *testing.T) {
			var (
				contentDir fs.FS
				err        error
			)
			if test.modulePath == stdlib.ModulePath {
				contentDir, _, _, err = stdlib.ContentDir(ctx, test.version)
				if err != nil {
					t.Fatal(err)
				}
			} else {
				proxyClient, teardownProxy := proxytest.SetupTestClient(t, []*proxytest.Module{
					{ModulePath: test.modulePath, Files: test.files}})
				defer teardownProxy()
				reader, err := proxyClient.Zip(ctx, test.modulePath, "v1.0.0")
				if err != nil {
					t.Fatal(err)
				}
				contentDir, err = fs.Sub(reader, test.modulePath+"@v1.0.0")
				if err != nil {
					t.Fatal(err)
				}
			}
			got, err := extractReadme(test.modulePath, test.pkgPath, test.version, contentDir)
			if err != nil {
				t.Fatal(err)
			}

			if diff := cmp.Diff(test.want, got); diff != "" {
				t.Errorf("mismatch (-want +got):\n%s", diff)
			}
		})
	}
}

func TestExtractReadmesError(t *testing.T) {
	ctx := context.Background()

	var (
		modulePath = "github.com/my/module"
		pkgPath    = "github.com/my/module/foo"
		version    = "v1.0.0"
		files      = map[string]string{
			"foo/README.md": string(make([]byte, MaxFileSize+100)),
		}
	)
	var (
		contentDir fs.FS
		err        error
	)
	proxyClient, teardownProxy := proxytest.SetupTestClient(t, []*proxytest.Module{
		{ModulePath: modulePath, Files: files}})
	defer teardownProxy()
	reader, err := proxyClient.Zip(ctx, modulePath, "v1.0.0")
	if err != nil {
		t.Fatal(err)
	}
	contentDir, err = fs.Sub(reader, modulePath+"@v1.0.0")
	if err != nil {
		t.Fatal(err)
	}
	got, err := extractReadme(modulePath, pkgPath, version, contentDir)
	if err == nil {
		t.Fatalf("want error, got %v", cmp.Diff([]*internal.Readme{}, got))
	}

	if !errors.Is(err, derrors.ModuleTooLarge) {
		t.Errorf("want ModuleTooLarge, got %v", err)
	}
}

func TestIsReadme(t *testing.T) {
	for _, test := range []struct {
		name, file string
		want       bool
	}{
		{
			name: "README in nested dir returns true",
			file: "github.com/my/module@v1.0.0/README.md",
			want: true,
		},
		{
			name: "case insensitive",
			file: "rEaDme",
			want: true,
		},
		{
			name: "random extension returns true",
			file: "README.FOO",
			want: true,
		},
		{
			name: "{prefix}readme will return false",
			file: "FOO_README",
			want: false,
		},
		{
			file: "README_FOO",
			name: "readme{suffix} will return false",
			want: false,
		},
		{
			file: "README.FOO.FOO",
			name: "README file with multiple extensions will return false",
			want: false,
		},
		{
			file: "readme.go",
			name: ".go README file will return false",
			want: false,
		},
		{
			file: "readme.vendor",
			name: ".vendor README file will return false",
			want: false,
		},
		{
			file: "",
			name: "empty filename returns false",
			want: false,
		},
	} {
		{
			t.Run(test.file, func(t *testing.T) {
				if got := isReadme(test.file); got != test.want {
					t.Errorf("isReadme(%q) = %t: %t", test.file, got, test.want)
				}
			})
		}
	}
}