package cabana

import (
	"context"
	"reflect"
	"testing"
	"time"

	"gorm.io/gorm"

	"git.golem15.com/golem15/summercms/modules/pact"
	"git.golem15.com/golem15/summercms/modules/towel"
)

// The D-92 record-event diff without a database: the snapshot taken before
// a save, the changes computed after it, and the value rules. The Postgres
// suite (record_events_postgres_test.go) covers every admin write path.

// rdArticle has a column of each kind a change reports.
type rdArticle struct {
	ID          uint       `gorm:"column:id;primaryKey"`
	Title       string     `gorm:"column:title"`
	Views       int        `gorm:"column:views"`
	Note        *string    `gorm:"column:note"`
	Published   bool       `gorm:"column:published"`
	PublishedAt *time.Time `gorm:"column:published_at"`
	Body        []byte     `gorm:"column:body"`
	Ignored     string     `gorm:"-"`
	CreatedAt   time.Time
	UpdatedAt   time.Time
}

// rdWriter is a translation writer with en as the default locale and the
// stored non-default values in stored (field -> locale -> value).
type rdWriter struct {
	stored map[string]map[string]string
	calls  int
}

func (w *rdWriter) DefaultLocale(context.Context, *gorm.DB) (string, error) { return "en", nil }
func (w *rdWriter) EnabledLocales(context.Context, *gorm.DB) ([]string, error) {
	return []string{"en", "pl", "de"}, nil
}
func (w *rdWriter) WriteTranslated(context.Context, *gorm.DB, any, string, string, string) error {
	return nil
}
func (w *rdWriter) TranslatedExact(_ context.Context, _ *gorm.DB, _ any, field, locale string) (string, bool, error) {
	w.calls++
	v, ok := w.stored[field][locale]
	return v, ok, nil
}

func rdStr(s string) *string { return &s }

func TestRecordEventDiff(t *testing.T) {
	db, _ := openDryRunDB(t)
	ctx := context.Background()
	at := time.Date(2026, 10, 27, 12, 0, 0, 0, time.UTC)

	cases := []struct {
		name   string
		before *rdArticle // nil: a create
		after  rdArticle
		want   []pact.RecordChange
	}{
		{"create lists the non-zero columns with a nil Old",
			nil,
			rdArticle{ID: 7, Title: "Hello", Note: rdStr("n"), CreatedAt: at, UpdatedAt: at},
			[]pact.RecordChange{{Attribute: "title", New: "Hello"}, {Attribute: "note", New: "n"}}},
		{"create of a zero record lists nothing",
			nil,
			rdArticle{ID: 7},
			[]pact.RecordChange{}},
		{"update reports a changed scalar column",
			&rdArticle{ID: 7, Title: "Old", Views: 3},
			rdArticle{ID: 7, Title: "New", Views: 3},
			[]pact.RecordChange{{Attribute: "title", Old: "Old", New: "New"}}},
		{"unchanged columns, the primary key and GORM timestamps are omitted",
			&rdArticle{ID: 7, Title: "Same", CreatedAt: at, UpdatedAt: at},
			rdArticle{ID: 7, Title: "Same", CreatedAt: at, UpdatedAt: at.Add(time.Hour)},
			[]pact.RecordChange{}},
		{"nil to value dereferences the pointer",
			&rdArticle{ID: 7},
			rdArticle{ID: 7, Note: rdStr("now set")},
			[]pact.RecordChange{{Attribute: "note", Old: nil, New: "now set"}}},
		{"value to nil",
			&rdArticle{ID: 7, Note: rdStr("gone")},
			rdArticle{ID: 7},
			[]pact.RecordChange{{Attribute: "note", Old: "gone", New: nil}}},
		{"times compare as instants",
			&rdArticle{ID: 7, PublishedAt: &at},
			rdArticle{ID: 7, PublishedAt: func() *time.Time { v := at.In(time.FixedZone("CET", 3600)); return &v }()},
			[]pact.RecordChange{}},
		{"a moved time is a change",
			&rdArticle{ID: 7, PublishedAt: &at},
			rdArticle{ID: 7, PublishedAt: func() *time.Time { v := at.Add(time.Minute); return &v }()},
			[]pact.RecordChange{{Attribute: "published_at", Old: at, New: at.Add(time.Minute)}}},
		{"several columns in declaration order",
			&rdArticle{ID: 7, Title: "a", Views: 1, Published: false},
			rdArticle{ID: 7, Title: "b", Views: 2, Published: true},
			[]pact.RecordChange{{Attribute: "title", Old: "a", New: "b"}, {Attribute: "views", Old: 1, New: 2}, {Attribute: "published", Old: false, New: true}}},
		{"byte columns compare by content",
			&rdArticle{ID: 7, Body: []byte("x")},
			rdArticle{ID: 7, Body: []byte("x")},
			[]pact.RecordChange{}},
	}
	for _, tc := range cases {
		t.Run(tc.name, func(t *testing.T) {
			var snap *recordSnapshot
			if tc.before != nil {
				var err error
				snap, err = takeRecordSnapshot(ctx, db, nil, tc.before, nil)
				if err != nil {
					t.Fatal(err)
				}
			}
			after := tc.after
			got, err := recordChanges(ctx, db, nil, &after, snap, nil)
			if err != nil {
				t.Fatal(err)
			}
			if !reflect.DeepEqual(got, tc.want) {
				t.Fatalf("changes = %#v\nwant %#v", got, tc.want)
			}
		})
	}

	t.Run("translated values per locale", func(t *testing.T) {
		writer := &rdWriter{stored: map[string]map[string]string{"title": {"pl": "Stary", "de": "Gleich"}}}
		submitted := []mlValue{{field: "title", values: map[string]string{"en": "New", "pl": "Nowy", "de": "Gleich", "fr": "Nouveau"}}}
		before := &rdArticle{ID: 7, Title: "Old"}
		snap, err := takeRecordSnapshot(ctx, db, writer, before, submitted)
		if err != nil {
			t.Fatal(err)
		}
		if _, asked := snap.translations["title"]["en"]; asked {
			t.Fatal("the snapshot read the default locale from the translation store")
		}
		after := &rdArticle{ID: 7, Title: "New"}
		got, err := recordChanges(ctx, db, writer, after, snap, submitted)
		if err != nil {
			t.Fatal(err)
		}
		want := []pact.RecordChange{
			{Attribute: "title", Old: "Old", New: "New"},
			{Attribute: "title", Locale: "fr", Old: nil, New: "Nouveau"},
			{Attribute: "title", Locale: "pl", Old: "Stary", New: "Nowy"},
		}
		if !reflect.DeepEqual(got, want) {
			t.Fatalf("changes = %#v\nwant %#v", got, want)
		}
	})

	t.Run("translated values on create", func(t *testing.T) {
		writer := &rdWriter{}
		submitted := []mlValue{{field: "title", values: map[string]string{"en": "Hello", "pl": "Cześć", "de": ""}}}
		got, err := recordChanges(ctx, db, writer, &rdArticle{ID: 7, Title: "Hello"}, nil, submitted)
		if err != nil {
			t.Fatal(err)
		}
		want := []pact.RecordChange{
			{Attribute: "title", New: "Hello"},
			{Attribute: "title", Locale: "pl", New: "Cześć"},
		}
		if !reflect.DeepEqual(got, want) {
			t.Fatalf("changes = %#v\nwant %#v", got, want)
		}
	})

	t.Run("no translation store is asked without submitted translations", func(t *testing.T) {
		writer := &rdWriter{}
		snap, err := takeRecordSnapshot(ctx, db, writer, &rdArticle{ID: 7}, nil)
		if err != nil {
			t.Fatal(err)
		}
		if _, err := recordChanges(ctx, db, writer, &rdArticle{ID: 7}, snap, nil); err != nil {
			t.Fatal(err)
		}
		if writer.calls != 0 {
			t.Fatalf("TranslatedExact called %d times", writer.calls)
		}
	})

	t.Run("a model GORM cannot parse reports nothing", func(t *testing.T) {
		snap, err := takeRecordSnapshot(ctx, db, nil, 42, nil)
		if err != nil || len(snap.columns) != 0 {
			t.Fatalf("snapshot = %+v, %v", snap, err)
		}
		got, err := recordChanges(ctx, db, nil, 42, snap, nil)
		if err != nil || len(got) != 0 {
			t.Fatalf("changes = %+v, %v", got, err)
		}
	})
}

func TestRecordEventDiffValues(t *testing.T) {
	s := "x"
	var nilStr *string
	slice := []string{"a"}
	m := map[string]int{"a": 1}
	for _, tc := range []struct {
		name string
		in   any
		want any
	}{
		{"nil", nil, nil},
		{"a value", 3, 3},
		{"a pointer is dereferenced", &s, "x"},
		{"a nil pointer is nil", nilStr, nil},
		{"a nil slice is nil", []string(nil), nil},
		{"a nil map is nil", map[string]int(nil), nil},
		{"a slice is copied", slice, []string{"a"}},
		{"a map is copied", m, map[string]int{"a": 1}},
	} {
		t.Run(tc.name, func(t *testing.T) {
			if got := changeValue(tc.in); !reflect.DeepEqual(got, tc.want) {
				t.Fatalf("changeValue(%#v) = %#v, want %#v", tc.in, got, tc.want)
			}
		})
	}

	t.Run("a copied slice and map do not follow later writes", func(t *testing.T) {
		gotSlice := changeValue(slice).([]string)
		gotMap := changeValue(m).(map[string]int)
		slice[0], m["a"] = "changed", 2
		if gotSlice[0] != "a" || gotMap["a"] != 1 {
			t.Fatalf("copies followed the model: %v %v", gotSlice, gotMap)
		}
	})

	at := time.Date(2026, 10, 27, 12, 0, 0, 0, time.UTC)
	for _, tc := range []struct {
		name string
		a, b any
		same bool
	}{
		{"equal strings", "a", "a", true},
		{"different strings", "a", "b", false},
		{"the same instant in two zones", at, at.In(time.FixedZone("X", 7200)), true},
		{"two instants", at, at.Add(time.Second), false},
		{"nil and nil", nil, nil, true},
		{"nil and a value", nil, "", false},
		{"int and int64 differ", 1, int64(1), false},
	} {
		t.Run("same "+tc.name, func(t *testing.T) {
			if got := sameChangeValue(tc.a, tc.b); got != tc.same {
				t.Fatalf("sameChangeValue(%#v, %#v) = %v", tc.a, tc.b, got)
			}
		})
	}

	t.Run("columnValue converts to the column type", func(t *testing.T) {
		type tree struct {
			ParentID  *uint `gorm:"column:parent_id"`
			SortOrder int   `gorm:"column:sort_order"`
		}
		if got := columnValue(&tree{}, "parent_id", float64(4)); got != uint(4) {
			t.Fatalf("parent_id = %#v", got)
		}
		if got := columnValue(&tree{}, "sort_order", int64(2)); got != 2 {
			t.Fatalf("sort_order = %#v", got)
		}
		if got := columnValue(&tree{}, "missing", "v"); got != "v" {
			t.Fatalf("missing column = %#v", got)
		}
		if got := columnValue(&tree{}, "sort_order", nil); got != nil {
			t.Fatalf("nil = %#v", got)
		}
	})
}

// TestRecordEventLocale (WR-02): an admin record event reports the primary
// tag of the request locale, never a raw Accept-Language header.
func TestRecordEventLocale(t *testing.T) {
	for in, want := range map[string]string{
		"":                           "",
		"pl":                         "pl",
		"pl-PL,pl;q=0.9,en-US;q=0.8": "pl-PL",
		" en ; q=1":                  "en",
	} {
		ctx := context.Background()
		if in != "" {
			ctx = towel.WithLocale(ctx, in)
		}
		if got := eventLocale(ctx); got != want {
			t.Errorf("eventLocale(%q) = %q, want %q", in, got, want)
		}
	}
}