// Copyright 2019 The Go Cloud Development Kit Authors
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     https://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

package memdocstore

import (
	"context"
	"io"
	"os"
	"path/filepath"
	"slices"
	"testing"

	"github.com/google/go-cmp/cmp"
	"gocloud.dev/docstore"
	"gocloud.dev/docstore/driver"
	"gocloud.dev/docstore/drivertest"
)

type harness struct{}

func newHarness(ctx context.Context, t *testing.T) (drivertest.Harness, error) {
	t.Helper()

	return &harness{}, nil
}

func (h *harness) MakeCollection(_ context.Context, kind drivertest.CollectionKind) (driver.Collection, error) {
	switch kind {
	case drivertest.SingleKey, drivertest.NoRev:
		return newCollection(drivertest.KeyField, nil, nil)
	case drivertest.TwoKey:
		return newCollection("", drivertest.HighScoreKey, nil)
	case drivertest.AltRev:
		return newCollection(drivertest.KeyField, nil, &Options{RevisionField: drivertest.AlternateRevisionField})
	default:
		panic("bad kind")
	}
}

func (*harness) BeforeDoTypes() []any    { return nil }
func (*harness) BeforeQueryTypes() []any { return nil }

func (*harness) RevisionsEqual(rev1, rev2 any) bool { return rev1 == rev2 }

func (*harness) SupportsAtomicWrites() bool { return true }

func (*harness) Close() {}

func TestConformance(t *testing.T) {
	// CodecTester is nil because memdocstore has no native representation.
	drivertest.RunConformanceTests(t, newHarness, nil, nil)
}

type docmap = map[string]any

// memdocstore-specific tests.

// The following tests test memdocstore's backend implementation.

func TestUpdateEncodesValues(t *testing.T) {
	// Check that update encodes the values in mods.
	ctx := context.Background()
	dc, err := newCollection(drivertest.KeyField, nil, nil)
	if err != nil {
		t.Fatal(err)
	}
	coll := docstore.NewCollection(dc)
	defer coll.Close()
	doc := docmap{drivertest.KeyField: "testUpdateEncodes", "a": 1, dc.RevisionField(): nil}
	if err := coll.Put(ctx, doc); err != nil {
		t.Fatal(err)
	}
	if err := coll.Update(ctx, doc, docstore.Mods{"a": 2}); err != nil {
		t.Fatal(err)
	}
	got := docmap{drivertest.KeyField: doc[drivertest.KeyField]}
	// This Get will fail if the int value 2 in the above mod was not encoded to an int64.
	if err := coll.Get(ctx, got); err != nil {
		t.Fatal(err)
	}
	want := docmap{
		drivertest.KeyField: doc[drivertest.KeyField],
		"a":                 int64(2),
		dc.RevisionField():  got[dc.RevisionField()],
	}
	if !cmp.Equal(got, want) {
		t.Errorf("got %v, want %v", got, want)
	}
}

func TestUpdateAtomic(t *testing.T) {
	// Check that update is atomic.
	ctx := context.Background()
	dc, err := newCollection(drivertest.KeyField, nil, nil)
	if err != nil {
		t.Fatal(err)
	}
	coll := docstore.NewCollection(dc)
	defer coll.Close()
	doc := docmap{drivertest.KeyField: "testUpdateAtomic", "a": "A", "b": "B", dc.RevisionField(): nil}

	mods := docstore.Mods{"a": "Y", "b.c": "Z"} // "b" is not a map, so "b.c" is an error
	if err := coll.Put(ctx, doc); err != nil {
		t.Fatal(err)
	}
	if errs := coll.Actions().Update(doc, mods).Do(ctx); errs == nil {
		t.Fatal("got nil, want errors")
	}
	got := docmap{drivertest.KeyField: doc[drivertest.KeyField]}
	if err := coll.Get(ctx, got); err != nil {
		t.Fatal(err)
	}
	want := docmap{
		drivertest.KeyField: doc[drivertest.KeyField],
		dc.RevisionField():  got[dc.RevisionField()],
		"a":                 "A",
		"b":                 "B",
	}
	if !cmp.Equal(got, want) {
		t.Errorf("got %v, want %v", got, want)
	}
}

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

	dc, err := newCollection(drivertest.KeyField, nil, &Options{AllowNestedSliceQueries: true})
	if err != nil {
		t.Fatal(err)
	}
	coll := docstore.NewCollection(dc)
	defer coll.Close()

	// Set up test documents
	testDocs := []docmap{{
		drivertest.KeyField: "TestQueryNested",
		"list":              []any{docmap{"a": "A"}},
		"map":               docmap{"b": "B"},
		"listOfMaps":        []any{docmap{"id": "1"}, docmap{"id": "2"}, docmap{"id": "3"}},
		"mapOfLists":        docmap{"ids": []any{"1", "2", "3"}},
		"deep":              []any{docmap{"nesting": []any{docmap{"of": docmap{"elements": "yes"}}}}},
		"listOfLists":       []any{docmap{"items": []any{docmap{"price": 10}, docmap{"price": 20}}}},
		dc.RevisionField():  nil,
	}, {
		drivertest.KeyField: "CheapItems",
		"items":             []any{docmap{"price": 10}, docmap{"price": 1}},
		dc.RevisionField():  nil,
	}, {
		drivertest.KeyField: "ExpensiveItems",
		"items":             []any{docmap{"price": 50}, docmap{"price": 100}},
		dc.RevisionField():  nil,
	}}

	for _, testDoc := range testDocs {
		err = coll.Put(ctx, testDoc)
		if err != nil {
			t.Fatal(err)
		}
	}

	tests := []struct {
		name     string
		where    []any
		wantKeys []string
	}{
		{
			name:     "list field match",
			where:    []any{"list.a", "=", "A"},
			wantKeys: []string{"TestQueryNested"},
		}, {
			name:  "list field no match",
			where: []any{"list.a", "=", "missing"},
		}, {
			name:     "map field match",
			where:    []any{"map.b", "=", "B"},
			wantKeys: []string{"TestQueryNested"},
		}, {
			name:     "list of maps field match",
			where:    []any{"listOfMaps.id", "=", "2"},
			wantKeys: []string{"TestQueryNested"},
		}, {
			name:     "map of lists field match",
			where:    []any{"mapOfLists.ids", "=", "1"},
			wantKeys: []string{"TestQueryNested"},
		}, {
			name:     "deep nested field match",
			where:    []any{"deep.nesting.of.elements", "=", "yes"},
			wantKeys: []string{"TestQueryNested"},
		}, {
			name:     "list of lists exact price 10",
			where:    []any{"listOfLists.items.price", "=", 10},
			wantKeys: []string{"TestQueryNested"},
		}, {
			name:     "list of lists exact price 20",
			where:    []any{"listOfLists.items.price", "=", 20},
			wantKeys: []string{"TestQueryNested"},
		}, {
			name:     "list of lists price less than or equal to 20",
			where:    []any{"listOfLists.items.price", "<=", 20},
			wantKeys: []string{"TestQueryNested"},
		}, {
			name:     "items price equals 1",
			where:    []any{"items.price", "=", 1},
			wantKeys: []string{"CheapItems"},
		}, {
			name:  "items price equals 5 (no match)",
			where: []any{"items.price", "=", 5},
		}, {
			name:     "items price greater than or equal to 1",
			where:    []any{"items.price", ">=", 1},
			wantKeys: []string{"CheapItems", "ExpensiveItems"},
		}, {
			name:     "items price greater than or equal to 5",
			where:    []any{"items.price", ">=", 5},
			wantKeys: []string{"CheapItems", "ExpensiveItems"},
		}, {
			name:     "items price greater than or equal to 10",
			where:    []any{"items.price", ">=", 10},
			wantKeys: []string{"CheapItems", "ExpensiveItems"},
		}, {
			name:     "items price less than or equal to 50",
			where:    []any{"items.price", "<=", 50},
			wantKeys: []string{"CheapItems", "ExpensiveItems"},
		},
	}

	for _, tc := range tests {
		t.Run(tc.name, func(t *testing.T) {
			iter := coll.Query().Where(docstore.FieldPath(tc.where[0].(string)), tc.where[1].(string), tc.where[2]).Get(ctx)
			var got []docmap
			for {
				doc := docmap{}
				err := iter.Next(ctx, doc)
				if err != nil {
					if err == io.EOF {
						break
					}
					t.Fatal(err)
				}
				got = append(got, doc)
			}

			// Extract keys from results
			var gotKeys []string
			for _, d := range got {
				if key, ok := d[drivertest.KeyField].(string); ok {
					gotKeys = append(gotKeys, key)
				}
			}
			slices.Sort(gotKeys)

			diff := cmp.Diff(gotKeys, tc.wantKeys)
			if diff != "" {
				t.Errorf("query results mismatch (-got +want):\n%s", diff)
			}
		})
	}
}

func TestSortDocs(t *testing.T) {
	newDocs := func() []storedDoc {
		return []storedDoc{
			{"a": int64(1), "b": "1", "c": 3.0},
			{"a": int64(2), "b": "2", "c": 4.0},
			{"a": int64(3), "b": "3"}, // missing "c"
		}
	}
	inorder := newDocs()
	reversed := newDocs()
	for i := 0; i < len(reversed)/2; i++ {
		j := len(reversed) - i - 1
		reversed[i], reversed[j] = reversed[j], reversed[i]
	}

	for _, test := range []struct {
		field     string
		ascending bool
		want      []storedDoc
	}{
		{"a", true, inorder},
		{"a", false, reversed},
		{"b", true, inorder},
		{"b", false, reversed},
		{"c", true, inorder},
		{"c", false, []storedDoc{inorder[1], inorder[0], inorder[2]}},
	} {
		got := newDocs()
		sortDocs(got, test.field, test.ascending)
		if diff := cmp.Diff(got, test.want); diff != "" {
			t.Errorf("%q, asc=%t:\n%s", test.field, test.ascending, diff)
		}
	}
}

func TestSaveAndLoad(t *testing.T) {
	dir := t.TempDir()

	// Load from nonexistent file should return empty data.
	f := filepath.Join(dir, "saveAndLoad")
	got, err := loadDocs(f)
	if err != nil {
		t.Fatalf("loading from nonexistent file, got %v, want nil", err)
	}
	if len(got) != 0 {
		t.Fatalf("loading from nonexistent file, got %v, want empty map", got)
	}

	// Save some data into the file.
	docs := map[any]storedDoc{
		"k1": {"key": "k1", "a": 1},
		"k2": {"key": "k2", "b": 2},
	}
	if err := saveDocs(f, docs); err != nil {
		t.Fatal(err)
	}
	// File should exist now.
	if _, err := os.Lstat(f); err != nil {
		t.Fatal(err)
	}

	// Reload the data.
	got, err = loadDocs(f)
	if err != nil {
		t.Fatal(err)
	}
	if !cmp.Equal(got, docs) {
		t.Errorf("\ngot  %v\nwant %v", got, docs)
	}
}
