package main

import (
	"errors"
	"fmt"
	"path/filepath"
	"unsafe"

	"github.com/dgraph-io/badger/v4"
	"github.com/ying32/govcl/vcl"
)

type badgerLoadedDatabase struct {
	displayName string
	db          *badger.DB
	nav         *vcl.TTreeNode

	arena []*navData // keepalive
}

func (ld *badgerLoadedDatabase) DisplayName() string {
	return ld.displayName
}

func (ld *badgerLoadedDatabase) DriverName() string {
	return "Badger v4"
}

func (ld *badgerLoadedDatabase) RootElement() *vcl.TTreeNode {
	return ld.nav
}

func (ld *badgerLoadedDatabase) Keepalive(ndata *navData) {
	ld.arena = append(ld.arena, ndata)
}

func (ld *badgerLoadedDatabase) RenderForNav(f *TMainForm, ndata *navData) {

	// Load properties

	content := fmt.Sprintf("Table statistics: %#v", ld.db.Tables())
	f.propertiesBox.SetText(content)

	// Load data
	// Badger always uses Key + Value as the columns

	colKey := f.contentBox.Columns().Add()
	colKey.Title().SetCaption("Key")
	colVal := f.contentBox.Columns().Add()
	colVal.Title().SetCaption("Value")

	err := ld.db.View(func(txn *badger.Txn) error {

		// Create iterator
		opts := badger.DefaultIteratorOptions
		opts.PrefetchSize = 64
		it := txn.NewIterator(opts)
		defer it.Close()

		for it.Rewind(); it.Valid(); it.Next() {
			item := it.Item()
			k := item.Key()
			err := item.Value(func(v []byte) error {
				rpos := f.contentBox.RowCount()
				f.contentBox.SetRowCount(rpos + 1)
				f.contentBox.SetCells(0, rpos, formatUtf8(k))
				f.contentBox.SetCells(1, rpos, formatUtf8(v))

				return nil
			})
			if err != nil {
				return err
			}
		}
		return nil
	})
	if err != nil {
		vcl.ShowMessage(fmt.Sprintf("Failed to load data: %s", err.Error()))
		return
	}

	// Valid
	vcl_stringgrid_columnwidths(f.contentBox)
	f.contentBox.SetEnabled(true)
}

func (n *badgerLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
	return errors.New("Editing is not supported")
}

func (ld *badgerLoadedDatabase) NavChildren(ndata *navData) ([]string, error) {
	// In the Badger implementation, there is only one child: "Data"
	if len(ndata.bucketPath) == 0 {
		return []string{"Data"}, nil

	} else {
		// No children deeper than that
		return []string{}, nil
	}
}

func (ld *badgerLoadedDatabase) NavContext(ndata *navData) ([]contextAction, error) {
	return nil, nil // No special actions are supported
}

func (ld *badgerLoadedDatabase) ExecQuery(query string, resultArea *vcl.TStringGrid) error {
	return errors.New("Badger doesn't support querying")
}

func (ld *badgerLoadedDatabase) Close() {
	_ = ld.db.Close()
	ld.arena = nil
}

var _ loadedDatabase = &badgerLoadedDatabase{} // interface assertion

//

func (f *TMainForm) badgerAddDatabaseFromMemory() {
	f.badgerAddDatabaseFrom(badger.DefaultOptions("").WithInMemory(true))
}

func (f *TMainForm) badgerAddDatabaseFromDirectory(path string) {
	f.badgerAddDatabaseFrom(badger.DefaultOptions(path))
}

func (f *TMainForm) badgerAddDatabaseFrom(opts badger.Options) {
	// TODO load in background thread to stop blocking the UI
	db, err := badger.Open(opts)
	if err != nil {
		vcl.ShowMessage(fmt.Sprintf("Failed to load database: %s", err.Error()))
		return
	}

	ld := &badgerLoadedDatabase{
		db: db,
	}

	if opts.Dir == "" {
		ld.displayName = ":memory:" // SQLite-style naming
	} else {
		ld.displayName = filepath.Base(opts.Dir)
	}

	ld.nav = f.Buckets.Items().Add(nil, ld.displayName)
	ld.nav.SetHasChildren(true) // dynamically populate in OnNavExpanding
	ld.nav.SetImageIndex(imgDatabase)
	ld.nav.SetSelectedIndex(imgDatabase)
	navData := &navData{
		ld:             ld,
		childrenLoaded: false,      // will be loaded dynamically
		bucketPath:     []string{}, // empty = root
	}
	ld.nav.SetData(unsafe.Pointer(navData))

	f.dbs = append(f.dbs, ld)
	f.Buckets.SetSelected(ld.nav) // Select new element

	ld.Keepalive(navData)
}