combobox.go

// Copyright 2010 The Walk Authors. All rights reserved.
// Use of this source code is governed by a BSD-style
// license that can be found in the LICENSE file.

// +build windows

package walk

import (
	"fmt"
	"math/big"
	"reflect"
	"strconv"
	"syscall"
	"time"
	"unsafe"

	"github.com/lxn/win"
)

type ComboBox struct {
	WidgetBase
	bindingValueProvider         BindingValueProvider
	model                        ListModel
	providedModel                interface{}
	bindingMember                string
	displayMember                string
	format                       string
	precision                    int
	itemsResetHandlerHandle      int
	itemChangedHandlerHandle     int
	itemsInsertedHandlerHandle   int
	itemsRemovedHandlerHandle    int
	maxItemTextWidth             int
	prevCurIndex                 int
	selChangeIndex               int
	maxLength                    int
	currentIndexChangedPublisher EventPublisher
	textChangedPublisher         EventPublisher
	editingFinishedPublisher     EventPublisher
	editOrigWndProcPtr           uintptr
	editing                      bool
	persistent                   bool
}

var comboBoxEditWndProcPtr uintptr

func init() {
	AppendToWalkInit(func() {
		comboBoxEditWndProcPtr = syscall.NewCallback(comboBoxEditWndProc)
	})
}

func comboBoxEditWndProc(hwnd win.HWND, msg uint32, wParam, lParam uintptr) uintptr {
	cb := (*ComboBox)(unsafe.Pointer(win.GetWindowLongPtr(hwnd, win.GWLP_USERDATA)))

	switch msg {
	case win.WM_GETDLGCODE:
		if !cb.editing {
			if form := ancestor(cb); form != nil {
				if dlg, ok := form.(dialogish); ok {
					if dlg.DefaultButton() != nil {
						// If the ComboBox lives in a Dialog that has a
						// DefaultButton, we won't swallow the return key.
						break
					}
				}
			}
		}

		if wParam == win.VK_RETURN {
			return win.DLGC_WANTALLKEYS
		}

	case win.WM_KEYDOWN:
		if wParam != win.VK_RETURN || 0 == cb.SendMessage(win.CB_GETDROPPEDSTATE, 0, 0) {
			cb.handleKeyDown(wParam, lParam)
		}

		if cb.editing && wParam == win.VK_RETURN {
			cb.editing = false
			cb.editingFinishedPublisher.Publish()
		}

	case win.WM_KEYUP:
		if wParam != win.VK_RETURN || 0 == cb.SendMessage(win.CB_GETDROPPEDSTATE, 0, 0) {
			cb.handleKeyUp(wParam, lParam)
		}

	case win.WM_SETFOCUS, win.WM_KILLFOCUS:
		cb.invalidateBorderInParent()

		if cb.editing && msg == win.WM_KILLFOCUS {
			cb.editing = false
			cb.editingFinishedPublisher.Publish()
		}
	}

	return win.CallWindowProc(cb.editOrigWndProcPtr, hwnd, msg, wParam, lParam)
}

func NewComboBox(parent Container) (*ComboBox, error) {
	cb, err := newComboBoxWithStyle(parent, win.CBS_AUTOHSCROLL|win.CBS_DROPDOWN)
	if err != nil {
		return nil, err
	}

	editHwnd := win.GetWindow(cb.hWnd, win.GW_CHILD)

	win.SetWindowLongPtr(editHwnd, win.GWLP_USERDATA, uintptr(unsafe.Pointer(cb)))
	cb.editOrigWndProcPtr = win.SetWindowLongPtr(editHwnd, win.GWLP_WNDPROC, comboBoxEditWndProcPtr)

	return cb, nil
}

func NewDropDownBox(parent Container) (*ComboBox, error) {
	return newComboBoxWithStyle(parent, win.CBS_DROPDOWNLIST)
}

func newComboBoxWithStyle(parent Container, style uint32) (*ComboBox, error) {
	cb := &ComboBox{prevCurIndex: -1, selChangeIndex: -1, precision: 2}

	if err := InitWidget(
		cb,
		parent,
		"COMBOBOX",
		win.WS_TABSTOP|win.WS_VISIBLE|win.WS_VSCROLL|style,
		0); err != nil {
		return nil, err
	}

	succeeded := false
	defer func() {
		if !succeeded {
			cb.Dispose()
		}
	}()

	var event *Event
	if style&win.CBS_DROPDOWNLIST == win.CBS_DROPDOWNLIST {
		event = cb.CurrentIndexChanged()
	} else {
		event = cb.TextChanged()
	}

	cb.GraphicsEffects().Add(InteractionEffect)
	cb.GraphicsEffects().Add(FocusEffect)

	cb.MustRegisterProperty("CurrentIndex", NewProperty(
		func() interface{} {
			return cb.CurrentIndex()
		},
		func(v interface{}) error {
			return cb.SetCurrentIndex(assertIntOr(v, -1))
		},
		cb.CurrentIndexChanged()))

	cb.MustRegisterProperty("Text", NewProperty(
		func() interface{} {
			return cb.Text()
		},
		func(v interface{}) error {
			return cb.SetText(assertStringOr(v, ""))
		},
		event))

	cb.MustRegisterProperty("CurrentItem", NewReadOnlyProperty(
		func() interface{} {
			if rlm, ok := cb.providedModel.(ReflectListModel); ok {
				if i := cb.CurrentIndex(); i > -1 {
					return reflect.ValueOf(rlm.Items()).Index(i).Interface()
				}
			}

			return nil
		},
		cb.CurrentIndexChanged()))

	cb.MustRegisterProperty("HasCurrentItem", NewReadOnlyBoolProperty(
		func() bool {
			return cb.CurrentIndex() != -1
		},
		cb.CurrentIndexChanged()))

	cb.MustRegisterProperty("TextNotEmpty", NewReadOnlyBoolProperty(
		func() bool {
			return cb.Text() != ""
		},
		cb.CurrentIndexChanged()))

	cb.MustRegisterProperty("Value", NewProperty(
		func() interface{} {
			if cb.Editable() {
				return cb.Text()
			}

			index := cb.CurrentIndex()

			if cb.bindingValueProvider == nil || index == -1 {
				return nil
			}

			return cb.bindingValueProvider.BindingValue(index)
		},
		func(v interface{}) error {
			if cb.Editable() {
				return cb.SetText(assertStringOr(v, ""))
			}

			if cb.bindingValueProvider == nil {
				if cb.model == nil {
					return nil
				} else {
					return newError("Data binding is only supported using a model that implements BindingValueProvider.")
				}
			}

			index := -1

			count := cb.model.ItemCount()
			for i := 0; i < count; i++ {
				if cb.bindingValueProvider.BindingValue(i) == v {
					index = i
					break
				}
			}

			return cb.SetCurrentIndex(index)
		},
		event))

	succeeded = true

	return cb, nil
}

func (cb *ComboBox) applyFont(font *Font) {
	cb.WidgetBase.applyFont(font)

	if cb.model != nil {
		cb.maxItemTextWidth = cb.calculateMaxItemTextWidth()
		cb.RequestLayout()
	}
}

func (cb *ComboBox) Editable() bool {
	return !cb.hasStyleBits(win.CBS_DROPDOWNLIST)
}

func (cb *ComboBox) itemString(index int) string {
	switch val := cb.model.Value(index).(type) {
	case string:
		return val

	case time.Time:
		return val.Format(cb.format)

	case *big.Rat:
		return val.FloatString(cb.precision)

	default:
		return fmt.Sprintf(cb.format, val)
	}

	panic("unreachable")
}

func (cb *ComboBox) insertItemAt(index int) error {
	str := cb.itemString(index)
	lp := uintptr(unsafe.Pointer(syscall.StringToUTF16Ptr(str)))

	if win.CB_ERR == cb.SendMessage(win.CB_INSERTSTRING, uintptr(index), lp) {
		return newError("SendMessage(CB_INSERTSTRING)")
	}

	return nil
}

func (cb *ComboBox) removeItem(index int) error {
	if win.CB_ERR == cb.SendMessage(win.CB_DELETESTRING, uintptr(index), 0) {
		return newError("SendMessage(CB_DELETESTRING")
	}

	return nil
}

func (cb *ComboBox) resetItems() error {
	cb.SetSuspended(true)
	defer cb.SetSuspended(false)

	cb.selChangeIndex = -1

	if win.FALSE == cb.SendMessage(win.CB_RESETCONTENT, 0, 0) {
		return newError("SendMessage(CB_RESETCONTENT)")
	}

	cb.maxItemTextWidth = 0

	cb.SetCurrentIndex(-1)

	if cb.model == nil {
		return nil
	}

	count := cb.model.ItemCount()

	for i := 0; i < count; i++ {
		if err := cb.insertItemAt(i); err != nil {
			return err
		}
	}

	cb.RequestLayout()

	return nil
}

func (cb *ComboBox) attachModel() {
	itemsResetHandler := func() {
		cb.resetItems()
	}
	cb.itemsResetHandlerHandle = cb.model.ItemsReset().Attach(itemsResetHandler)

	itemChangedHandler := func(index int) {
		if win.CB_ERR == cb.SendMessage(win.CB_DELETESTRING, uintptr(index), 0) {
			newError("SendMessage(CB_DELETESTRING)")
		}

		cb.insertItemAt(index)

		cb.SetCurrentIndex(cb.prevCurIndex)
	}
	cb.itemChangedHandlerHandle = cb.model.ItemChanged().Attach(itemChangedHandler)

	cb.itemsInsertedHandlerHandle = cb.model.ItemsInserted().Attach(func(from, to int) {
		for i := from; i <= to; i++ {
			cb.insertItemAt(i)
		}
	})

	cb.itemsRemovedHandlerHandle = cb.model.ItemsRemoved().Attach(func(from, to int) {
		for i := to; i >= from; i-- {
			cb.removeItem(i)
		}
	})
}

func (cb *ComboBox) detachModel() {
	cb.model.ItemsReset().Detach(cb.itemsResetHandlerHandle)
	cb.model.ItemChanged().Detach(cb.itemChangedHandlerHandle)
	cb.model.ItemsInserted().Detach(cb.itemsInsertedHandlerHandle)
	cb.model.ItemsRemoved().Detach(cb.itemsRemovedHandlerHandle)
}

// Model returns the model of the ComboBox.
func (cb *ComboBox) Model() interface{} {
	return cb.providedModel
}

// SetModel sets the model of the ComboBox.
//
// It is required that mdl either implements walk.ListModel or
// walk.ReflectListModel or be a slice of pointers to struct or a []string.
func (cb *ComboBox) SetModel(mdl interface{}) error {
	model, ok := mdl.(ListModel)
	if !ok && mdl != nil {
		var err error
		if model, err = newReflectListModel(mdl); err != nil {
			return err
		}

		if _, ok := mdl.([]string); !ok {
			if badms, ok := model.(bindingAndDisplayMemberSetter); ok {
				var bindingMember string
				if cb.Editable() {
					bindingMember = cb.displayMember
				} else {
					bindingMember = cb.bindingMember
				}
				badms.setBindingMember(bindingMember)
				badms.setDisplayMember(cb.displayMember)
			}
		}
	}
	cb.providedModel = mdl

	if cb.model != nil {
		cb.detachModel()
	}

	cb.model = model
	cb.bindingValueProvider, _ = model.(BindingValueProvider)

	if model != nil {
		cb.attachModel()
	}

	if err := cb.resetItems(); err != nil {
		return err
	}

	if !cb.Editable() && model != nil && model.ItemCount() == 1 {
		cb.SetCurrentIndex(0)
	}

	return cb.Invalidate()
}

// BindingMember returns the member from the model of the ComboBox that is bound
// to a field of the data source managed by an associated DataBinder.
//
// This is only applicable to walk.ReflectListModel models and simple slices of
// pointers to struct.
func (cb *ComboBox) BindingMember() string {
	return cb.bindingMember
}

// SetBindingMember sets the member from the model of the ComboBox that is bound
// to a field of the data source managed by an associated DataBinder.
//
// This is only applicable to walk.ReflectListModel models and simple slices of
// pointers to struct.
//
// For a model consisting of items of type S, data source field of type T and
// bindingMember "Foo", this can be one of the following:
//
//	A field		Foo T
//	A method	func (s S) Foo() T
//	A method	func (s S) Foo() (T, error)
//
// If bindingMember is not a simple member name like "Foo", but a path to a
// member like "A.B.Foo", members "A" and "B" both must be one of the options
// mentioned above, but with T having type pointer to struct.
func (cb *ComboBox) SetBindingMember(bindingMember string) error {
	if bindingMember != "" {
		if _, ok := cb.providedModel.([]string); ok {
			return newError("invalid for []string model")
		}
	}

	cb.bindingMember = bindingMember

	if badms, ok := cb.model.(bindingAndDisplayMemberSetter); ok {
		badms.setBindingMember(bindingMember)
	}

	return nil
}

// DisplayMember returns the member from the model of the ComboBox that is
// displayed in the ComboBox.
//
// This is only applicable to walk.ReflectListModel models and simple slices of
// pointers to struct.
func (cb *ComboBox) DisplayMember() string {
	return cb.displayMember
}

// SetDisplayMember sets the member from the model of the ComboBox that is
// displayed in the ComboBox.
//
// This is only applicable to walk.ReflectListModel models and simple slices of
// pointers to struct.
//
// For a model consisting of items of type S, the type of the specified member T
// and displayMember "Foo", this can be one of the following:
//
//	A field		Foo T
//	A method	func (s S) Foo() T
//	A method	func (s S) Foo() (T, error)
//
// If displayMember is not a simple member name like "Foo", but a path to a
// member like "A.B.Foo", members "A" and "B" both must be one of the options
// mentioned above, but with T having type pointer to struct.
func (cb *ComboBox) SetDisplayMember(displayMember string) error {
	if displayMember != "" {
		if _, ok := cb.providedModel.([]string); ok {
			return newError("invalid for []string model")
		}
	}

	cb.displayMember = displayMember

	if badms, ok := cb.model.(bindingAndDisplayMemberSetter); ok {
		badms.setDisplayMember(displayMember)
	}

	return nil
}

func (cb *ComboBox) Format() string {
	return cb.format
}

func (cb *ComboBox) SetFormat(value string) {
	cb.format = value
}

func (cb *ComboBox) Precision() int {
	return cb.precision
}

func (cb *ComboBox) SetPrecision(value int) {
	cb.precision = value
}

func (cb *ComboBox) MaxLength() int {
	return cb.maxLength
}

func (cb *ComboBox) SetMaxLength(value int) {
	cb.SendMessage(win.CB_LIMITTEXT, uintptr(value), 0)

	cb.maxLength = value
}

func (cb *ComboBox) calculateMaxItemTextWidth() int {
	hdc := win.GetDC(cb.hWnd)
	if hdc == 0 {
		newError("GetDC failed")
		return -1
	}
	defer win.ReleaseDC(cb.hWnd, hdc)

	hFontOld := win.SelectObject(hdc, win.HGDIOBJ(cb.Font().handleForDPI(cb.DPI())))
	defer win.SelectObject(hdc, hFontOld)

	var maxWidth int

	count := cb.model.ItemCount()
	for i := 0; i < count; i++ {
		var s win.SIZE
		str := syscall.StringToUTF16(cb.itemString(i))

		if !win.GetTextExtentPoint32(hdc, &str[0], int32(len(str)-1), &s) {
			newError("GetTextExtentPoint32 failed")
			return -1
		}

		maxWidth = maxi(maxWidth, int(s.CX))
	}

	return maxWidth
}

func (cb *ComboBox) CurrentIndex() int {
	return int(int32(cb.SendMessage(win.CB_GETCURSEL, 0, 0)))
}

func (cb *ComboBox) SetCurrentIndex(value int) error {
	index := int(int32(cb.SendMessage(win.CB_SETCURSEL, uintptr(value), 0)))

	if index != value {
		return newError("invalid index")
	}

	if value != cb.prevCurIndex {
		cb.prevCurIndex = value
		cb.currentIndexChangedPublisher.Publish()
	}

	return nil
}

func (cb *ComboBox) CurrentIndexChanged() *Event {
	return cb.currentIndexChangedPublisher.Event()
}

func (cb *ComboBox) Text() string {
	return cb.text()
}

func (cb *ComboBox) SetText(value string) error {
	if err := cb.setText(value); err != nil {
		return err
	}

	cb.textChangedPublisher.Publish()

	return nil
}

func (cb *ComboBox) TextSelection() (start, end int) {
	cb.SendMessage(win.CB_GETEDITSEL, uintptr(unsafe.Pointer(&start)), uintptr(unsafe.Pointer(&end)))
	return
}

func (cb *ComboBox) SetTextSelection(start, end int) {
	cb.SendMessage(win.CB_SETEDITSEL, 0, uintptr(win.MAKELONG(uint16(start), uint16(end))))
}

func (cb *ComboBox) TextChanged() *Event {
	return cb.textChangedPublisher.Event()
}

func (cb *ComboBox) EditingFinished() *Event {
	return cb.editingFinishedPublisher.Event()
}

func (cb *ComboBox) Persistent() bool {
	return cb.persistent
}

func (cb *ComboBox) SetPersistent(value bool) {
	cb.persistent = value
}

func (cb *ComboBox) SaveState() error {
	cb.WriteState(strconv.Itoa(cb.CurrentIndex()))

	return nil
}

func (cb *ComboBox) RestoreState() error {
	state, err := cb.ReadState()
	if err != nil {
		return err
	}
	if state == "" {
		return nil
	}

	if i, err := strconv.Atoi(state); err == nil {
		cb.SetCurrentIndex(i)
	}

	return nil
}

func (cb *ComboBox) WndProc(hwnd win.HWND, msg uint32, wParam, lParam uintptr) uintptr {
	switch msg {
	case win.WM_COMMAND:
		code := win.HIWORD(uint32(wParam))
		selIndex := cb.CurrentIndex()

		switch code {
		case win.CBN_EDITCHANGE:
			cb.editing = true
			cb.selChangeIndex = -1
			cb.textChangedPublisher.Publish()

		case win.CBN_SELCHANGE:
			cb.selChangeIndex = selIndex

		case win.CBN_SELENDCANCEL:
			if cb.selChangeIndex != -1 {
				if cb.selChangeIndex < cb.model.ItemCount() {
					cb.SetCurrentIndex(cb.selChangeIndex)
				}

				cb.selChangeIndex = -1
			}

		case win.CBN_SELENDOK:
			if editable := cb.Editable(); editable || selIndex != cb.prevCurIndex {
				if editable && selIndex > -1 {
					cb.Property("Value").Set(cb.model.Value(selIndex))
				}
				cb.currentIndexChangedPublisher.Publish()
				cb.prevCurIndex = selIndex
				return 0
			}

			cb.selChangeIndex = -1
		}

	case win.WM_MOUSEWHEEL:
		if !cb.Enabled() {
			return 0
		}

	case win.WM_WINDOWPOSCHANGED:
		wp := (*win.WINDOWPOS)(unsafe.Pointer(lParam))

		if wp.Flags&win.SWP_NOSIZE != 0 {
			break
		}

		if cb.Editable() {
			result := cb.WidgetBase.WndProc(hwnd, msg, wParam, lParam)

			cb.SetTextSelection(0, 0)

			return result
		}
	}

	return cb.WidgetBase.WndProc(hwnd, msg, wParam, lParam)
}

func (*ComboBox) NeedsWmSize() bool {
	return true
}

func (cb *ComboBox) CreateLayoutItem(ctx *LayoutContext) LayoutItem {
	var layoutFlags LayoutFlags
	if cb.Editable() {
		layoutFlags = GrowableHorz | GreedyHorz
	} else {
		layoutFlags = GrowableHorz
	}

	defaultSize := cb.dialogBaseUnitsToPixels(Size{30, 12})

	if cb.model != nil && cb.maxItemTextWidth <= 0 {
		cb.maxItemTextWidth = cb.calculateMaxItemTextWidth()
	}

	// FIXME: Use GetThemePartSize instead of guessing
	w := maxi(defaultSize.Width, cb.maxItemTextWidth+int(win.GetSystemMetricsForDpi(win.SM_CXVSCROLL, uint32(ctx.dpi)))+8)
	h := defaultSize.Height + 1

	return &comboBoxLayoutItem{
		layoutFlags: layoutFlags,
		idealSize:   Size{w, h},
	}
}

type comboBoxLayoutItem struct {
	LayoutItemBase
	layoutFlags LayoutFlags
	idealSize   Size
}

func (li *comboBoxLayoutItem) LayoutFlags() LayoutFlags {
	return li.layoutFlags
}

func (li *comboBoxLayoutItem) IdealSize() Size {
	return li.idealSize
}

func (li *comboBoxLayoutItem) MinSize() Size {
	return li.idealSize
}