package main

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

	"yvbolt/debconf"

	"github.com/ying32/govcl/vcl"
)

type debconfLoadedDatabase struct {
	displayName string
	db          *debconf.Database
	nav         *vcl.TTreeNode

	arena []*navData // keepalive
}

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

func (ld *debconfLoadedDatabase) DriverName() string {
	return "debconf"
}

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

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

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

	// Load properties

	content := fmt.Sprintf("Entries: %d\nUnique attributes: %d\n", len(ld.db.Entries), len(ld.db.AllColumnNames))
	f.propertiesBox.SetText(content)

	// Load data

	f.contentBox.SetEnabled(false)
	f.contentBox.Clear()

	// debconf always uses Key + Value as the columns

	indexes := make(map[string]int)

	f.contentBox.Columns().Clear()
	for i, cname := range ld.db.AllColumnNames {
		indexes[cname] = i

		col := f.contentBox.Columns().Add()
		col.SetCaption(cname)
		col.SetWidth(MY_WIDTH)
	}

	for _, entry := range ld.db.Entries {

		cell := f.contentBox.Items().Add()
		cell.SetCaption(entry.Name)

		texts := make([]string, len(ld.db.AllColumnNames))
		for _, proppair := range entry.Properties {
			texts[indexes[proppair[0]]-1 /* compensate for 'Name' always being first */] = proppair[1]
		}
		cell.SubItems().AddStrings2(texts)
	}

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

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

func (ld *debconfLoadedDatabase) ExecQuery(query string, resultArea *vcl.TListView) {
	vcl.ShowMessage("debconf doesn't support querying")
}

func (ld *debconfLoadedDatabase) Close() {
	ld.arena = nil
}

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

//

func (f *TMainForm) debconfAddDatabaseFrom(path string) {
	// TODO load in background thread to stop blocking the UI

	fh, err := os.OpenFile(path, os.O_RDONLY, 0400)
	if err != nil {
		vcl.ShowMessage(fmt.Sprintf("Failed to load database: %s", err.Error()))
		return
	}
	defer fh.Close()

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

	ld := &debconfLoadedDatabase{
		db:          db,
		displayName: filepath.Base(path),
	}

	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)
}