// Package convmv provides the convmv command.
package convmv

import (
	"cmp"
	"context"
	"fmt"
	"path/filepath"
	"slices"
	"strings"
	"testing"

	_ "github.com/rclone/rclone/backend/all" // import all backends
	"github.com/rclone/rclone/fs/filter"
	"github.com/rclone/rclone/fs/operations"
	"github.com/rclone/rclone/fs/walk"
	"github.com/rclone/rclone/lib/encoder"
	"golang.org/x/text/unicode/norm"

	"github.com/rclone/rclone/fs"
	"github.com/rclone/rclone/fstest"
	"github.com/stretchr/testify/assert"
	"github.com/stretchr/testify/require"
)

// Some times used in the tests
var (
	t1    = fstest.Time("2001-02-03T04:05:06.499999999Z")
	debug = ``
)

// TestMain drives the tests
func TestMain(m *testing.M) {
	fstest.TestMain(m)
}

func TestConvmv(t *testing.T) {
	type args struct {
		ConvertAlgo     fs.Enum[convertChoices]
		ConvertBackAlgo fs.Enum[convertChoices]
		Lossless        bool // whether the ConvertBackAlgo is always losslessly invertible
		ExtraOpt        ConvOpt
	}
	tests := []struct {
		name string
		args args
	}{
		{name: "NFC", args: args{ConvertAlgo: ConvToNFC, ConvertBackAlgo: ConvToNFD, Lossless: false}},
		{name: "NFD", args: args{ConvertAlgo: ConvToNFD, ConvertBackAlgo: ConvToNFC, Lossless: false}},
		{name: "NFKC", args: args{ConvertAlgo: ConvToNFKC, ConvertBackAlgo: ConvToNFKD, Lossless: false}},
		{name: "NFKD", args: args{ConvertAlgo: ConvToNFKD, ConvertBackAlgo: ConvToNFKC, Lossless: false}},
		{name: "base64", args: args{ConvertAlgo: ConvBase64Encode, ConvertBackAlgo: ConvBase64Decode, Lossless: true}},
		{name: "replace", args: args{ConvertAlgo: ConvFindReplace, ConvertBackAlgo: ConvFindReplace, Lossless: true, ExtraOpt: ConvOpt{FindReplace: []string{"bread,banana", "pie,apple", "apple,pie", "banana,bread"}}}},
		{name: "prefix", args: args{ConvertAlgo: ConvPrefix, ConvertBackAlgo: ConvTrimPrefix, Lossless: true, ExtraOpt: ConvOpt{Prefix: "PREFIX"}}},
		{name: "suffix", args: args{ConvertAlgo: ConvSuffix, ConvertBackAlgo: ConvTrimSuffix, Lossless: true, ExtraOpt: ConvOpt{Suffix: "SUFFIX"}}},
		{name: "truncate", args: args{ConvertAlgo: ConvTruncate, ConvertBackAlgo: ConvTruncate, Lossless: false, ExtraOpt: ConvOpt{Max: 10}}},
		{name: "encoder", args: args{ConvertAlgo: ConvEncoder, ConvertBackAlgo: ConvDecoder, Lossless: true, ExtraOpt: ConvOpt{Enc: encoder.OS}}},
		{name: "ISO-8859-1", args: args{ConvertAlgo: ConvISO8859_1, ConvertBackAlgo: ConvISO8859_1, Lossless: false}},
		{name: "charmap", args: args{ConvertAlgo: ConvCharmap, ConvertBackAlgo: ConvCharmap, Lossless: false, ExtraOpt: ConvOpt{CmapFlag: 3}}},
		{name: "lowercase", args: args{ConvertAlgo: ConvLowercase, ConvertBackAlgo: ConvUppercase, Lossless: false}},
		{name: "ascii", args: args{ConvertAlgo: ConvASCII, ConvertBackAlgo: ConvASCII, Lossless: false}},
	}
	for _, tt := range tests {
		t.Run(tt.name, func(t *testing.T) {
			r := fstest.NewRun(t)
			defer r.Finalise()

			items := makeTestFiles(t, r, "dir1")
			deleteDSStore(t, r)
			r.CheckRemoteListing(t, items, nil)

			Opt = tt.args.ExtraOpt
			Opt.ConvertAlgo = tt.args.ConvertAlgo
			err := Convmv(context.Background(), r.Fremote, "")
			assert.NoError(t, err)
			compareNames(t, r, items)

			convertedItems := convertItems(t, items)
			Opt.ConvertAlgo = tt.args.ConvertBackAlgo
			err = Convmv(context.Background(), r.Fremote, "")
			assert.NoError(t, err)
			compareNames(t, r, convertedItems)

			if tt.args.Lossless {
				deleteDSStore(t, r)
				r.CheckRemoteItems(t, items...)
			}
		})
	}
}

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var extras = []string{"apple", "banana", "appleappleapplebanana", "splitbananasplit"}

func makeTestFiles(t *testing.T, r *fstest.Run, dir string) []fstest.Item {
	t.Helper()
	n := 0
	// Create test files
	items := []fstest.Item{}
	for _, c := range alphabet {
		var out strings.Builder
		for i := rune(0); i < 32; i++ {
			out.WriteRune(c + i)
		}
		fileName := filepath.Join(dir, fmt.Sprintf("%04d-%s.txt", n, out.String()))
		fileName = strings.ToValidUTF8(fileName, "")

		if debug != "" {
			fileName = debug
		}

		item := r.WriteObject(context.Background(), fileName, fileName, t1)
		items = append(items, item)
		n++

		if debug != "" {
			break
		}
	}

	for _, extra := range extras {
		item := r.WriteObject(context.Background(), extra, extra, t1)
		items = append(items, item)
	}

	return items
}

func deleteDSStore(t *testing.T, r *fstest.Run) {
	ctxDSStore, fi := filter.AddConfig(context.Background())
	err := fi.AddRule(`+ *.DS_Store`)
	assert.NoError(t, err)
	err = fi.AddRule(`- **`)
	assert.NoError(t, err)
	err = operations.Delete(ctxDSStore, r.Fremote)
	assert.NoError(t, err)
}

func compareNames(t *testing.T, r *fstest.Run, items []fstest.Item) {
	var entries fs.DirEntries

	deleteDSStore(t, r)
	err := walk.ListR(context.Background(), r.Fremote, "", true, -1, walk.ListObjects, func(e fs.DirEntries) error {
		entries = append(entries, e...)
		return nil
	})
	assert.NoError(t, err)
	entries = slices.DeleteFunc(entries, func(E fs.DirEntry) bool { // remove those pesky .DS_Store files
		if strings.Contains(E.Remote(), ".DS_Store") {
			err := operations.DeleteFile(context.Background(), E.(fs.Object))
			assert.NoError(t, err)
			return true
		}
		return false
	})
	require.Equal(t, len(items), entries.Len())

	// sort by CONVERTED name
	slices.SortStableFunc(items, func(a, b fstest.Item) int {
		aConv, err := ConvertPath(a.Path, Opt.ConvertAlgo, false)
		require.NoError(t, err, a.Path)
		bConv, err := ConvertPath(b.Path, Opt.ConvertAlgo, false)
		require.NoError(t, err, b.Path)
		return cmp.Compare(aConv, bConv)
	})
	slices.SortStableFunc(entries, func(a, b fs.DirEntry) int {
		return cmp.Compare(a.Remote(), b.Remote())
	})

	for i, e := range entries {
		expect, err := ConvertPath(items[i].Path, Opt.ConvertAlgo, false)
		assert.NoError(t, err)
		msg := fmt.Sprintf("expected %v, got %v", detectEncoding(expect), detectEncoding(e.Remote()))
		assert.Equal(t, expect, e.Remote(), msg)
	}
}

func convertItems(t *testing.T, items []fstest.Item) []fstest.Item {
	convertedItems := []fstest.Item{}
	for _, item := range items {
		newPath, err := ConvertPath(item.Path, Opt.ConvertAlgo, false)
		assert.NoError(t, err)
		newItem := item
		newItem.Path = newPath
		convertedItems = append(convertedItems, newItem)
	}
	return convertedItems
}

func detectEncoding(s string) string {
	if norm.NFC.IsNormalString(s) && norm.NFD.IsNormalString(s) {
		return "BOTH"
	}
	if !norm.NFC.IsNormalString(s) && norm.NFD.IsNormalString(s) {
		return "NFD"
	}
	if norm.NFC.IsNormalString(s) && !norm.NFD.IsNormalString(s) {
		return "NFC"
	}
	return "OTHER"
}