// Copyright 2011 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 (
	"strconv"
	"syscall"
	"unsafe"

	"github.com/xuchengzhi/win"
)

const tabWidgetWindowClass = `\o/ Walk_TabWidget_Class \o/`

func init() {
	MustRegisterWindowClass(tabWidgetWindowClass)
}

type TabWidget struct {
	WidgetBase
	hWndTab                      win.HWND
	tabOrigWndProcPtr            uintptr
	imageList                    *ImageList
	pages                        *TabPageList
	currentIndex                 int
	currentIndexChangedPublisher EventPublisher
	persistent                   bool
}

func NewTabWidget(parent Container) (*TabWidget, error) {
	tw := &TabWidget{currentIndex: -1}
	tw.pages = newTabPageList(tw)

	if err := InitWidget(
		tw,
		parent,
		tabWidgetWindowClass,
		win.WS_VISIBLE,
		win.WS_EX_CONTROLPARENT); err != nil {
		return nil, err
	}

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

	tw.SetPersistent(true)

	tw.hWndTab = win.CreateWindowEx(
		0, syscall.StringToUTF16Ptr("SysTabControl32"), nil,
		win.WS_CHILD|win.WS_CLIPSIBLINGS|win.WS_TABSTOP|win.WS_VISIBLE,
		0, 0, 0, 0, tw.hWnd, 0, 0, nil)
	if tw.hWndTab == 0 {
		return nil, lastError("CreateWindowEx")
	}

	win.SetWindowLongPtr(tw.hWndTab, win.GWLP_USERDATA, uintptr(unsafe.Pointer(tw)))
	tw.tabOrigWndProcPtr = win.SetWindowLongPtr(tw.hWndTab, win.GWLP_WNDPROC, tabWidgetTabWndProcPtr)

	win.SendMessage(tw.hWndTab, win.WM_SETFONT, uintptr(defaultFont.handleForDPI(0)), 1)

	tw.applyFont(tw.Font())

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

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

	succeeded = true

	return tw, nil
}

func (tw *TabWidget) Dispose() {
	tw.WidgetBase.Dispose()

	if tw.imageList != nil {
		tw.imageList.Dispose()
		tw.imageList = nil
	}
}

func (tw *TabWidget) LayoutFlags() LayoutFlags {
	if tw.pages.Len() == 0 {
		return ShrinkableHorz | ShrinkableVert | GrowableHorz | GrowableVert | GreedyHorz | GreedyVert
	}

	var flags LayoutFlags

	for i := tw.pages.Len() - 1; i >= 0; i-- {
		flags |= tw.pages.At(i).LayoutFlags()
	}

	return flags
}

func (tw *TabWidget) MinSizeHint() Size {
	if tw.pages.Len() == 0 {
		return tw.SizeHint()
	}

	var min Size

	for i := tw.pages.Len() - 1; i >= 0; i-- {
		s := tw.pages.At(i).MinSizeHint()

		min.Width = maxi(min.Width, s.Width)
		min.Height = maxi(min.Height, s.Height)
	}

	b := tw.BoundsPixels()
	pb := tw.pages.At(0).BoundsPixels()

	size := Size{b.Width - pb.Width + min.Width, b.Height - pb.Height + min.Height}

	return size
}

func (tw *TabWidget) HeightForWidth(width int) int {
	if tw.pages.Len() == 0 {
		return 0
	}

	var height int
	margin := tw.SizePixels()
	pageSize := tw.pages.At(0).SizePixels()

	margin.Width -= pageSize.Width
	margin.Height -= pageSize.Height

	for i := tw.pages.Len() - 1; i >= 0; i-- {
		h := tw.pages.At(i).HeightForWidth(width + margin.Width)

		height = maxi(height, h)
	}

	return height + margin.Height
}

func (tw *TabWidget) SizeHint() Size {
	return Size{100, 100}
}

func (tw *TabWidget) applyEnabled(enabled bool) {
	tw.WidgetBase.applyEnabled(enabled)

	setWindowEnabled(tw.hWndTab, enabled)

	applyEnabledToDescendants(tw, enabled)
}

func (tw *TabWidget) applyFont(font *Font) {
	tw.WidgetBase.applyFont(font)

	SetWindowFont(tw.hWndTab, font)

	// FIXME: won't work with ApplyDPI
	// applyFontToDescendants(tw, font)
}

func (tw *TabWidget) ApplyDPI(dpi int) {
	tw.WidgetBase.ApplyDPI(dpi)

	var maskColor Color
	var size Size
	if tw.imageList != nil {
		maskColor = tw.imageList.maskColor
		size = tw.imageList.imageSize96dpi
	} else {
		size = Size{16, 16}
	}

	iml, err := newImageList(size, maskColor, dpi)
	if err != nil {
		return
	}

	win.SendMessage(tw.hWndTab, win.TCM_SETIMAGELIST, 0, uintptr(iml.hIml))

	if tw.imageList != nil {
		tw.imageList.Dispose()
	}

	tw.imageList = iml

	for _, page := range tw.pages.items {
		tw.onPageChanged(page)
	}
}

func (tw *TabWidget) CurrentIndex() int {
	return tw.currentIndex
}

func (tw *TabWidget) SetCurrentIndex(index int) error {
	if index == tw.currentIndex {
		return nil
	}

	if index < 0 || index >= tw.pages.Len() {
		return newError("invalid index")
	}

	ret := int(win.SendMessage(tw.hWndTab, win.TCM_SETCURSEL, uintptr(index), 0))
	if ret == -1 {
		return newError("SendMessage(TCM_SETCURSEL) failed")
	}

	// FIXME: The SendMessage(TCM_SETCURSEL) call above doesn't cause a
	// TCN_SELCHANGE notification, so we use this workaround.
	tw.onSelChange()

	return nil
}

func (tw *TabWidget) CurrentIndexChanged() *Event {
	return tw.currentIndexChangedPublisher.Event()
}

func (tw *TabWidget) Pages() *TabPageList {
	return tw.pages
}

func (tw *TabWidget) Persistent() bool {
	return tw.persistent
}

func (tw *TabWidget) SetPersistent(value bool) {
	tw.persistent = value
}

func (tw *TabWidget) SaveState() error {
	tw.WriteState(strconv.Itoa(tw.CurrentIndex()))

	for _, page := range tw.pages.items {
		if err := page.SaveState(); err != nil {
			return err
		}
	}

	return nil
}

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

	index, err := strconv.Atoi(state)
	if err != nil {
		return err
	}
	if index >= 0 && index < tw.pages.Len() {
		if err := tw.SetCurrentIndex(index); err != nil {
			return err
		}
	}

	for _, page := range tw.pages.items {
		if err := page.RestoreState(); err != nil {
			return err
		}
	}

	return nil
}

func (tw *TabWidget) resizePages() {
	var r win.RECT
	if !win.GetWindowRect(tw.hWndTab, &r) {
		lastError("GetWindowRect")
		return
	}

	p := win.POINT{
		r.Left,
		r.Top,
	}
	if !win.ScreenToClient(tw.hWnd, &p) {
		newError("ScreenToClient failed")
		return
	}

	r = win.RECT{
		p.X,
		p.Y,
		r.Right - r.Left + p.X,
		r.Bottom - r.Top + p.Y,
	}
	win.SendMessage(tw.hWndTab, win.TCM_ADJUSTRECT, 0, uintptr(unsafe.Pointer(&r)))

	for _, page := range tw.pages.items {
		if err := page.SetBoundsPixels(
			Rectangle{
				int(r.Left - 2),
				int(r.Top),
				int(r.Right - r.Left + 2),
				int(r.Bottom - r.Top),
			}); err != nil {

			return
		}
	}
}

func (tw *TabWidget) onResize(lParam uintptr) {
	r := win.RECT{0, 0, win.GET_X_LPARAM(lParam), win.GET_Y_LPARAM(lParam)}
	if !win.MoveWindow(tw.hWndTab, r.Left, r.Top, r.Right-r.Left, r.Bottom-r.Top, true) {
		lastError("MoveWindow")
		return
	}

	tw.resizePages()
}

func (tw *TabWidget) onSelChange() {
	pageCount := tw.pages.Len()

	if tw.currentIndex > -1 && tw.currentIndex < pageCount {
		page := tw.pages.At(tw.currentIndex)
		page.SetVisible(false)
	}

	tw.currentIndex = int(int32(win.SendMessage(tw.hWndTab, win.TCM_GETCURSEL, 0, 0)))

	if tw.currentIndex > -1 && tw.currentIndex < pageCount {
		page := tw.pages.At(tw.currentIndex)
		page.SetVisible(true)
		page.Invalidate()
		tw.pages.At(tw.currentIndex).focusFirstCandidateDescendant()
	}

	tw.Invalidate()

	tw.currentIndexChangedPublisher.Publish()
}

func (tw *TabWidget) WndProc(hwnd win.HWND, msg uint32, wParam, lParam uintptr) uintptr {
	if tw.hWndTab != 0 {
		switch msg {
		case win.WM_ERASEBKGND:
			return 1

		//case win.WM_PAINT:
		//	return 0

		case win.WM_SIZE, win.WM_SIZING:
			tw.onResize(lParam)

		case win.WM_NOTIFY:
			nmhdr := (*win.NMHDR)(unsafe.Pointer(lParam))

			switch int32(nmhdr.Code) {
			case win.TCN_SELCHANGE:
				tw.onSelChange()
			}
		}
	}

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

var tabWidgetTabWndProcPtr = syscall.NewCallback(tabWidgetTabWndProc)

func tabWidgetTabWndProc(hwnd win.HWND, msg uint32, wParam, lParam uintptr) uintptr {
	tw := (*TabWidget)(unsafe.Pointer(win.GetWindowLongPtr(hwnd, win.GWLP_USERDATA)))

	switch msg {
	case win.WM_MOUSEMOVE:
		win.InvalidateRect(hwnd, nil, true)

	case win.WM_ERASEBKGND:
		return 1

	case win.WM_PAINT:
		var ps win.PAINTSTRUCT

		hdc := win.BeginPaint(hwnd, &ps)
		defer win.EndPaint(hwnd, &ps)

		cb := tw.ClientBoundsPixels()

		bitmap, err := NewBitmap(cb.Size())
		if err != nil {
			break
		}
		defer bitmap.Dispose()

		canvas, err := NewCanvasFromImage(bitmap)
		if err != nil {
			break
		}
		defer canvas.Dispose()

		themed := win.IsAppThemed()

		if !themed {
			if err := canvas.FillRectangle(sysColorBtnFaceBrush, cb); err != nil {
				break
			}
		}

		win.SendMessage(hwnd, win.WM_PRINTCLIENT, uintptr(canvas.hdc), uintptr(win.PRF_CLIENT|win.PRF_CHILDREN|win.PRF_ERASEBKGND))

		parent := tw.Parent()
		if parent == nil {
			break
		}

		// Draw background of free area not occupied by tab items.
		if bg, wnd := parent.AsWindowBase().backgroundEffective(); bg != nil {
			tw.prepareDCForBackground(canvas.hdc, hwnd, wnd)

			hRgn := win.CreateRectRgn(0, 0, 0, 0)
			defer win.DeleteObject(win.HGDIOBJ(hRgn))

			var rc win.RECT

			count := tw.pages.Len()
			for i := 0; i < count; i++ {
				if 0 == win.SendMessage(hwnd, win.TCM_GETITEMRECT, uintptr(i), uintptr(unsafe.Pointer(&rc))) {
					break
				}

				if i == tw.currentIndex {
					rc.Left -= 2
					rc.Top -= 2
					rc.Right += 2
				} else {
					if i == count-1 && themed {
						rc.Right -= 2
					}
				}

				hRgnTab := win.CreateRectRgn(rc.Left, rc.Top, rc.Right, rc.Bottom)
				win.CombineRgn(hRgn, hRgn, hRgnTab, win.RGN_OR)
				win.DeleteObject(win.HGDIOBJ(hRgnTab))
			}

			hRgnRC := win.CreateRectRgn(0, 0, int32(cb.Width), rc.Bottom)
			win.CombineRgn(hRgn, hRgnRC, hRgn, win.RGN_DIFF)
			win.DeleteObject(win.HGDIOBJ(hRgnRC))

			if !win.FillRgn(canvas.hdc, hRgn, bg.handle()) {
				break
			}
		}

		// Draw current tab item.
		if tw.currentIndex != -1 {
			page := tw.pages.At(tw.CurrentIndex())

			if bg, wnd := page.AsWindowBase().backgroundEffective(); bg != nil &&
				bg != tabPageBackgroundBrush &&
				(page.layout == nil || !page.layout.Margins().isZero()) {

				tw.prepareDCForBackground(canvas.hdc, hwnd, wnd)

				var rc win.RECT
				if 0 == win.SendMessage(hwnd, win.TCM_GETITEMRECT, uintptr(tw.currentIndex), uintptr(unsafe.Pointer(&rc))) {
					break
				}

				hRgn := win.CreateRectRgn(rc.Left, rc.Top, rc.Right, rc.Bottom+2)
				defer win.DeleteObject(win.HGDIOBJ(hRgn))
				if !win.FillRgn(canvas.hdc, hRgn, bg.handle()) {
					break
				}

				if page.image != nil {
					x := rc.Left + 6
					y := rc.Top
					s := int32(16)

					bmp, err := iconCache.Bitmap(page.image, tw.DPI())
					if err == nil {
						if imageCanvas, err := NewCanvasFromImage(bmp); err == nil {
							defer imageCanvas.Dispose()

							if !win.TransparentBlt(
								canvas.hdc, x, y, s, s,
								imageCanvas.hdc, 0, 0, int32(bmp.size.Width), int32(bmp.size.Height),
								0) {
								break
							}
						}

						rc.Left += s + 6
					}
				}

				rc.Left += 6
				rc.Top += 1

				title := syscall.StringToUTF16(page.title)

				if themed {
					hTheme := win.OpenThemeData(hwnd, syscall.StringToUTF16Ptr("tab"))
					defer win.CloseThemeData(hTheme)

					options := win.DTTOPTS{DwFlags: win.DTT_GLOWSIZE, IGlowSize: 3}
					options.DwSize = uint32(unsafe.Sizeof(options))
					if hr := win.DrawThemeTextEx(hTheme, canvas.hdc, 0, win.TIS_SELECTED, &title[0], int32(len(title)), 0, &rc, &options); !win.SUCCEEDED(hr) {
						break
					}
				} else {
					if 0 == win.DrawTextEx(canvas.hdc, &title[0], int32(len(title)), &rc, 0, nil) {
						break
					}
				}
			}
		}

		if !win.BitBlt(hdc, 0, 0, int32(cb.Width), int32(cb.Height), canvas.hdc, 0, 0, win.SRCCOPY) {
			break
		}

		return 0
	}

	return win.CallWindowProc(tw.tabOrigWndProcPtr, hwnd, msg, wParam, lParam)
}

func (tw *TabWidget) onPageChanged(page *TabPage) (err error) {
	index := tw.pages.Index(page)
	item := tw.tcitemFromPage(page)

	if 0 == win.SendMessage(tw.hWndTab, win.TCM_SETITEM, uintptr(index), uintptr(unsafe.Pointer(item))) {
		return newError("SendMessage(TCM_SETITEM) failed")
	}

	return nil
}

func (tw *TabWidget) onInsertingPage(index int, page *TabPage) (err error) {
	return nil
}

func (tw *TabWidget) onInsertedPage(index int, page *TabPage) (err error) {
	item := tw.tcitemFromPage(page)

	if idx := int(win.SendMessage(tw.hWndTab, win.TCM_INSERTITEM, uintptr(index), uintptr(unsafe.Pointer(item)))); idx == -1 {
		return newError("SendMessage(TCM_INSERTITEM) failed")
	}

	page.SetVisible(false)

	style := uint32(win.GetWindowLong(page.hWnd, win.GWL_STYLE))
	if style == 0 {
		return lastError("GetWindowLong")
	}

	style |= win.WS_CHILD
	style &^= win.WS_POPUP

	win.SetLastError(0)
	if win.SetWindowLong(page.hWnd, win.GWL_STYLE, int32(style)) == 0 {
		return lastError("SetWindowLong")
	}

	if win.SetParent(page.hWnd, tw.hWnd) == 0 {
		return lastError("SetParent")
	}

	if tw.pages.Len() == 1 {
		page.SetVisible(true)
		tw.SetCurrentIndex(0)
	}

	tw.resizePages()

	page.tabWidget = tw

	page.applyFont(tw.Font())

	tw.Invalidate()

	return
}

func (tw *TabWidget) removePage(page *TabPage) (err error) {
	page.SetVisible(false)

	style := uint32(win.GetWindowLong(page.hWnd, win.GWL_STYLE))
	if style == 0 {
		return lastError("GetWindowLong")
	}

	style &^= win.WS_CHILD
	style |= win.WS_POPUP

	win.SetLastError(0)
	if win.SetWindowLong(page.hWnd, win.GWL_STYLE, int32(style)) == 0 {
		return lastError("SetWindowLong")
	}

	page.tabWidget = nil

	return page.SetParent(nil)
}

func (tw *TabWidget) onRemovingPage(index int, page *TabPage) (err error) {
	return nil
}

func (tw *TabWidget) onRemovedPage(index int, page *TabPage) (err error) {
	err = tw.removePage(page)
	if err != nil {
		return
	}

	win.SendMessage(tw.hWndTab, win.TCM_DELETEITEM, uintptr(index), 0)

	if tw.pages.Len() > 0 {
		tw.currentIndex = 0
		win.SendMessage(tw.hWndTab, win.TCM_SETCURSEL, uintptr(tw.currentIndex), 0)
	} else {
		tw.currentIndex = -1
	}
	tw.onSelChange()

	return

	// FIXME: Either make use of this unreachable code or remove it.
	if index == tw.currentIndex {
		// removal of current visible tabpage...
		tw.currentIndex = -1

		// select new tabpage if any :
		if tw.pages.Len() > 0 {
			// are we removing the rightmost page ?
			if index == tw.pages.Len()-1 {
				// If so, select the page on the left
				index -= 1
			}
		}
	}

	tw.SetCurrentIndex(index)

	tw.Invalidate()

	return
}

func (tw *TabWidget) onClearingPages(pages []*TabPage) (err error) {
	return nil
}

func (tw *TabWidget) onClearedPages(pages []*TabPage) (err error) {
	win.SendMessage(tw.hWndTab, win.TCM_DELETEALLITEMS, 0, 0)
	for _, page := range pages {
		tw.removePage(page)
	}
	tw.currentIndex = -1

	tw.Invalidate()

	return nil
}

func (tw *TabWidget) tcitemFromPage(page *TabPage) *win.TCITEM {
	var imageIndex int32 = -1
	if page.image != nil {
		if bmp, err := iconCache.Bitmap(page.image, tw.DPI()); err == nil {
			imageIndex, _ = tw.imageIndex(bmp)
		}
	}

	text := syscall.StringToUTF16(page.title)

	item := &win.TCITEM{
		Mask:       win.TCIF_IMAGE | win.TCIF_TEXT,
		IImage:     imageIndex,
		PszText:    &text[0],
		CchTextMax: int32(len(text)),
	}

	return item
}

func (tw *TabWidget) imageIndex(image *Bitmap) (index int32, err error) {
	index = -1
	if image != nil {
		if tw.imageList == nil {
			if tw.imageList, err = newImageList(Size{16, 16}, 0, tw.DPI()); err != nil {
				return
			}

			win.SendMessage(tw.hWndTab, win.TCM_SETIMAGELIST, 0, uintptr(tw.imageList.hIml))
		}

		if index, err = tw.imageList.AddMasked(image); err != nil {
			return
		}
	}

	return
}