package main

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

	"github.com/cockroachdb/pebble"
	"github.com/cockroachdb/pebble/vfs"
	"github.com/ying32/govcl/vcl"
)

type pebbleLoadedDatabase struct {
	displayName string
	db          *pebble.DB
	nav         *vcl.TTreeNode

	arena []*navData // keepalive
}

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

func (ld *pebbleLoadedDatabase) DriverName() string {
	return "Pebble " + version_Pebble // Parsed from embedded go.mod copy
}

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

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

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

	ctx := context.Background()

	// Load properties

	content := fmt.Sprintf("Pebble metrics: %#v", ld.db.Metrics())
	f.propertiesBox.SetText(content)

	// Load data
	// pebble 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")

	itr := ld.db.NewIterWithContext(ctx, nil)
	defer itr.Close()

	for itr.First(); itr.Valid(); itr.Next() {
		k := itr.Key()
		v, err := itr.ValueAndErr()
		if err != nil {
			vcl.ShowMessage(fmt.Sprintf("Failed to load data for key %q: %s", formatAny(k), err.Error()))
			return
		}

		rpos := f.contentBox.RowCount()
		f.contentBox.SetRowCount(rpos + 1)
		f.contentBox.SetCells(0, rpos, formatUtf8(k))
		f.contentBox.SetCells(0, rpos, formatUtf8(v))
	}

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

func (n *pebbleLoadedDatabase) ApplyChanges(f *TMainForm, ndata *navData) error {
	return ErrNotSupported
}

func (ld *pebbleLoadedDatabase) NavChildren(ndata *navData) ([]string, error) {
	// In the pebble 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 *pebbleLoadedDatabase) NavContext(ndata *navData) ([]contextAction, error) {
	return nil, nil // No special actions are supported
}

func (ld *pebbleLoadedDatabase) ExecQuery(query string, resultArea *vcl.TStringGrid) error {
	return ErrNotSupported
}

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

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

//

func (f *TMainForm) pebbleAddDatabaseFromMemory() {
	f.pebbleAddDatabaseFrom("", &pebble.Options{FS: vfs.NewMem()})
}

func (f *TMainForm) pebbleAddDatabaseFrom(dirname string, opts *pebble.Options) {
	// TODO load in background thread to stop blocking the UI

	db, err := pebble.Open(dirname, opts)
	if err != nil {
		vcl.ShowMessage(fmt.Sprintf("Failed to load database: %s", err.Error()))
		return
	}

	ld := &pebbleLoadedDatabase{
		db:          db,
		displayName: filepath.Base(dirname),
	}

	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)
}