/* SPDX-License-Identifier: MIT
 *
 * Copyright (C) 2019 WireGuard LLC. All Rights Reserved.
 */

package ui

import (
	"archive/zip"
	"fmt"
	"io/ioutil"
	"os"
	"path/filepath"
	"sort"
	"strings"

	"github.com/lxn/walk"

	"golang.zx2c4.com/wireguard/windows/conf"
	"golang.zx2c4.com/wireguard/windows/manager"
)

type TunnelsPage struct {
	*walk.TabPage

	listView      *ListView
	listContainer walk.Container
	listToolbar   *walk.ToolBar
	confView      *ConfView
	fillerButton  *walk.PushButton
	fillerHandler func()

	fillerContainer        *walk.Composite
	currentTunnelContainer *walk.Composite
}

func NewTunnelsPage() (*TunnelsPage, error) {
	var err error
	var disposables walk.Disposables
	defer disposables.Treat()

	tp := new(TunnelsPage)
	if tp.TabPage, err = walk.NewTabPage(); err != nil {
		return nil, err
	}
	disposables.Add(tp)

	tp.SetTitle("Tunnels")
	tp.SetLayout(walk.NewHBoxLayout())

	tp.listContainer, _ = walk.NewComposite(tp)
	vlayout := walk.NewVBoxLayout()
	vlayout.SetMargins(walk.Margins{})
	vlayout.SetSpacing(0)
	tp.listContainer.SetLayout(vlayout)

	if tp.listView, err = NewListView(tp.listContainer); err != nil {
		return nil, err
	}

	if tp.currentTunnelContainer, err = walk.NewComposite(tp); err != nil {
		return nil, err
	}
	vlayout = walk.NewVBoxLayout()
	vlayout.SetMargins(walk.Margins{})
	tp.currentTunnelContainer.SetLayout(vlayout)

	if tp.fillerContainer, err = walk.NewComposite(tp); err != nil {
		return nil, err
	}
	tp.fillerContainer.SetVisible(false)
	hlayout := walk.NewHBoxLayout()
	hlayout.SetMargins(walk.Margins{})
	tp.fillerContainer.SetLayout(hlayout)
	tp.fillerButton, _ = walk.NewPushButton(tp.fillerContainer)
	tp.fillerButton.SetMinMaxSize(walk.Size{200, 0}, walk.Size{200, 0})
	tp.fillerButton.Clicked().Attach(func() {
		if tp.fillerHandler != nil {
			tp.fillerHandler()
		}
	})

	if tp.confView, err = NewConfView(tp.currentTunnelContainer); err != nil {
		return nil, err
	}

	controlsContainer, err := walk.NewComposite(tp.currentTunnelContainer)
	if err != nil {
		return nil, err
	}
	controlsContainer.SetLayout(walk.NewHBoxLayout())
	controlsContainer.Layout().SetMargins(walk.Margins{})

	walk.NewHSpacer(controlsContainer)

	editTunnel, err := walk.NewPushButton(controlsContainer)
	if err != nil {
		return nil, err
	}
	editTunnel.SetEnabled(false)
	tp.listView.CurrentIndexChanged().Attach(func() {
		editTunnel.SetEnabled(tp.listView.CurrentIndex() > -1)
	})
	editTunnel.SetText("&Edit")
	editTunnel.Clicked().Attach(tp.onEditTunnel)

	disposables.Spare()

	tp.listView.ItemCountChanged().Attach(tp.onTunnelsChanged)
	tp.listView.SelectedIndexesChanged().Attach(tp.onSelectedTunnelsChanged)
	tp.listView.ItemActivated().Attach(tp.onTunnelsViewItemActivated)
	tp.listView.CurrentIndexChanged().Attach(tp.updateConfView)
	tp.listView.Load(false)
	tp.onTunnelsChanged()

	return tp, nil
}

func (tp *TunnelsPage) CreateToolbar() error {
	if tp.listToolbar != nil {
		return nil
	}

	// HACK: Because of https://github.com/lxn/walk/issues/481
	// we need to put the ToolBar into its own Composite.
	toolBarContainer, err := walk.NewComposite(tp.listContainer)
	if err != nil {
		return err
	}
	toolBarContainer.SetDoubleBuffering(true)
	hlayout := walk.NewHBoxLayout()
	hlayout.SetMargins(walk.Margins{})
	toolBarContainer.SetLayout(hlayout)

	if tp.listToolbar, err = walk.NewToolBarWithOrientationAndButtonStyle(toolBarContainer, walk.Horizontal, walk.ToolBarButtonImageBeforeText); err != nil {
		return err
	}

	addMenu, err := walk.NewMenu()
	if err != nil {
		return err
	}
	tp.AddDisposable(addMenu)
	importAction := walk.NewAction()
	importAction.SetText("&Import tunnel(s) from file...")
	importActionIcon, _ := loadSystemIcon("imageres", 3, 16)
	importAction.SetImage(importActionIcon)
	importAction.SetShortcut(walk.Shortcut{walk.ModControl, walk.KeyO})
	importAction.SetDefault(true)
	importAction.Triggered().Attach(tp.onImport)
	addMenu.Actions().Add(importAction)
	addAction := walk.NewAction()
	addAction.SetText("Add &empty tunnel...")
	addActionIcon, _ := loadSystemIcon("imageres", 2, 16)
	addAction.SetImage(addActionIcon)
	addAction.SetShortcut(walk.Shortcut{walk.ModControl, walk.KeyN})
	addAction.Triggered().Attach(tp.onAddTunnel)
	addMenu.Actions().Add(addAction)
	addMenuAction := walk.NewMenuAction(addMenu)
	addMenuActionIcon, _ := loadSystemIcon("shell32", 149, 16)
	addMenuAction.SetImage(addMenuActionIcon)
	addMenuAction.SetText("Add Tunnel")
	addMenuAction.SetToolTip(importAction.Text())
	addMenuAction.Triggered().Attach(tp.onImport)
	tp.listToolbar.Actions().Add(addMenuAction)

	tp.listToolbar.Actions().Add(walk.NewSeparatorAction())

	deleteAction := walk.NewAction()
	deleteActionIcon, _ := loadSystemIcon("shell32", 131, 16)
	deleteAction.SetImage(deleteActionIcon)
	deleteAction.SetShortcut(walk.Shortcut{0, walk.KeyDelete})
	deleteAction.SetToolTip("Remove selected tunnel(s)")
	deleteAction.Triggered().Attach(tp.onDelete)
	tp.listToolbar.Actions().Add(deleteAction)
	tp.listToolbar.Actions().Add(walk.NewSeparatorAction())

	exportAction := walk.NewAction()
	exportActionIcon, _ := loadSystemIcon("imageres", 165, 16) // Or "shell32", 45?
	exportAction.SetImage(exportActionIcon)
	exportAction.SetToolTip("Export all tunnels to zip...")
	exportAction.Triggered().Attach(tp.onExportTunnels)
	tp.listToolbar.Actions().Add(exportAction)

	fixContainerWidthToToolbarWidth := func() {
		toolbarWidth := tp.listToolbar.SizeHint().Width
		tp.listContainer.SetMinMaxSizePixels(walk.Size{toolbarWidth, 0}, walk.Size{toolbarWidth, 0})
	}
	fixContainerWidthToToolbarWidth()
	tp.listToolbar.SizeChanged().Attach(fixContainerWidthToToolbarWidth)

	contextMenu, err := walk.NewMenu()
	if err != nil {
		return err
	}
	tp.listView.AddDisposable(contextMenu)
	toggleAction := walk.NewAction()
	toggleAction.SetText("&Toggle")
	toggleAction.SetDefault(true)
	toggleAction.Triggered().Attach(tp.onTunnelsViewItemActivated)
	contextMenu.Actions().Add(toggleAction)
	contextMenu.Actions().Add(walk.NewSeparatorAction())
	importAction2 := walk.NewAction()
	importAction2.SetText("&Import tunnel(s) from file...")
	importAction2.SetShortcut(walk.Shortcut{walk.ModControl, walk.KeyO})
	importAction2.Triggered().Attach(tp.onImport)
	contextMenu.Actions().Add(importAction2)
	tp.ShortcutActions().Add(importAction2)
	addAction2 := walk.NewAction()
	addAction2.SetText("Add &empty tunnel...")
	addAction2.SetShortcut(walk.Shortcut{walk.ModControl, walk.KeyN})
	addAction2.Triggered().Attach(tp.onAddTunnel)
	contextMenu.Actions().Add(addAction2)
	tp.ShortcutActions().Add(addAction2)
	exportAction2 := walk.NewAction()
	exportAction2.SetText("Export all tunnels to &zip...")
	exportAction2.Triggered().Attach(tp.onExportTunnels)
	contextMenu.Actions().Add(exportAction2)
	contextMenu.Actions().Add(walk.NewSeparatorAction())
	editAction := walk.NewAction()
	editAction.SetText("Edit &selected tunnel...")
	editAction.SetShortcut(walk.Shortcut{walk.ModControl, walk.KeyE})
	editAction.Triggered().Attach(tp.onEditTunnel)
	contextMenu.Actions().Add(editAction)
	tp.ShortcutActions().Add(editAction)
	deleteAction2 := walk.NewAction()
	deleteAction2.SetText("&Remove selected tunnel(s)")
	deleteAction2.SetShortcut(walk.Shortcut{0, walk.KeyDelete})
	deleteAction2.Triggered().Attach(tp.onDelete)
	contextMenu.Actions().Add(deleteAction2)
	tp.listView.ShortcutActions().Add(deleteAction2)
	tp.listView.SetContextMenu(contextMenu)
	selectAllAction := walk.NewAction()
	selectAllAction.SetText("Select &all")
	selectAllAction.SetShortcut(walk.Shortcut{walk.ModControl, walk.KeyA})
	selectAllAction.Triggered().Attach(tp.onSelectAll)
	contextMenu.Actions().Add(selectAllAction)
	tp.listView.ShortcutActions().Add(selectAllAction)
	tp.listView.SetContextMenu(contextMenu)

	setSelectionOrientedOptions := func() {
		selected := len(tp.listView.SelectedIndexes())
		all := len(tp.listView.model.tunnels)
		deleteAction.SetEnabled(selected > 0)
		deleteAction2.SetEnabled(selected > 0)
		toggleAction.SetEnabled(selected == 1)
		selectAllAction.SetEnabled(selected < all)
		editAction.SetEnabled(selected == 1)
	}
	tp.listView.SelectedIndexesChanged().Attach(setSelectionOrientedOptions)
	setSelectionOrientedOptions()
	setExport := func() {
		all := len(tp.listView.model.tunnels)
		exportAction.SetEnabled(all > 0)
		exportAction2.SetEnabled(all > 0)
	}
	setExportRange := func(from, to int) { setExport() }
	tp.listView.model.RowsInserted().Attach(setExportRange)
	tp.listView.model.RowsRemoved().Attach(setExportRange)
	tp.listView.model.RowsReset().Attach(setExport)
	setExport()

	return nil
}

func (tp *TunnelsPage) updateConfView() {
	tp.confView.SetTunnel(tp.listView.CurrentTunnel())
}

func (tp *TunnelsPage) importFiles(paths []string) {
	go func() {
		syncedMsgBox := func(title string, message string, flags walk.MsgBoxStyle) {
			tp.Synchronize(func() {
				walk.MsgBox(tp.Form(), title, message, flags)
			})
		}
		type unparsedConfig struct {
			Name   string
			Config string
		}

		var (
			unparsedConfigs []unparsedConfig
			lastErr         error
		)

		for _, path := range paths {
			switch strings.ToLower(filepath.Ext(path)) {
			case ".conf":
				textConfig, err := ioutil.ReadFile(path)
				if err != nil {
					lastErr = err
					continue
				}
				unparsedConfigs = append(unparsedConfigs, unparsedConfig{Name: strings.TrimSuffix(filepath.Base(path), filepath.Ext(path)), Config: string(textConfig)})
			case ".zip":
				// 1 .conf + 1 error .zip edge case?
				r, err := zip.OpenReader(path)
				if err != nil {
					lastErr = err
					continue
				}

				for _, f := range r.File {
					if strings.ToLower(filepath.Ext(f.Name)) != ".conf" {
						continue
					}

					rc, err := f.Open()
					if err != nil {
						lastErr = err
						continue
					}
					textConfig, err := ioutil.ReadAll(rc)
					rc.Close()
					if err != nil {
						lastErr = err
						continue
					}
					unparsedConfigs = append(unparsedConfigs, unparsedConfig{Name: strings.TrimSuffix(filepath.Base(f.Name), filepath.Ext(f.Name)), Config: string(textConfig)})
				}

				r.Close()
			}
		}

		if lastErr != nil || unparsedConfigs == nil {
			syncedMsgBox("Error", fmt.Sprintf("Could not import selected configuration: %v", lastErr), walk.MsgBoxIconWarning)
			return
		}

		// Add in reverse order so that the first one is selected.
		sort.Slice(unparsedConfigs, func(i, j int) bool {
			return conf.TunnelNameIsLess(unparsedConfigs[j].Name, unparsedConfigs[i].Name)
		})

		existingTunnelList, err := manager.IPCClientTunnels()
		if err != nil {
			syncedMsgBox("Error", fmt.Sprintf("Could not enumerate existing tunnels: %v", lastErr), walk.MsgBoxIconWarning)
			return
		}
		existingLowerTunnels := make(map[string]bool, len(existingTunnelList))
		for _, tunnel := range existingTunnelList {
			existingLowerTunnels[strings.ToLower(tunnel.Name)] = true
		}

		configCount := 0
		tp.listView.SetSuspendTunnelsUpdate(true)
		for _, unparsedConfig := range unparsedConfigs {
			if existingLowerTunnels[strings.ToLower(unparsedConfig.Name)] {
				lastErr = fmt.Errorf("Another tunnel already exists with the name ‘%s’", unparsedConfig.Name)
				continue
			}
			config, err := conf.FromWgQuickWithUnknownEncoding(unparsedConfig.Config, unparsedConfig.Name)
			if err != nil {
				lastErr = err
				continue
			}
			_, err = manager.IPCClientNewTunnel(config)
			if err != nil {
				lastErr = err
				continue
			}
			configCount++
		}
		tp.listView.SetSuspendTunnelsUpdate(false)

		m, n := configCount, len(unparsedConfigs)
		switch {
		case n == 1 && m != n:
			syncedMsgBox("Error", fmt.Sprintf("Unable to import configuration: %v", lastErr), walk.MsgBoxIconWarning)
		case n == 1 && m == n:
			// nothing
		case m == n:
			syncedMsgBox("Imported tunnels", fmt.Sprintf("Imported %d tunnels", m), walk.MsgBoxIconInformation)
		case m != n:
			syncedMsgBox("Imported tunnels", fmt.Sprintf("Imported %d of %d tunnels", m, n), walk.MsgBoxIconWarning)
		}
	}()
}

func (tp *TunnelsPage) exportTunnels(filePath string) {
	writeFileWithOverwriteHandling(tp.Form(), filePath, func(file *os.File) error {
		writer := zip.NewWriter(file)

		for _, tunnel := range tp.listView.model.tunnels {
			cfg, err := tunnel.StoredConfig()
			if err != nil {
				return fmt.Errorf("onExportTunnels: tunnel.StoredConfig failed: %v", err)
			}

			w, err := writer.Create(tunnel.Name + ".conf")
			if err != nil {
				return fmt.Errorf("onExportTunnels: writer.Create failed: %v", err)
			}

			if _, err := w.Write(([]byte)(cfg.ToWgQuick())); err != nil {
				return fmt.Errorf("onExportTunnels: cfg.ToWgQuick failed: %v", err)
			}
		}

		return writer.Close()
	})
}

func (tp *TunnelsPage) addTunnel(config *conf.Config) {
	_, err := manager.IPCClientNewTunnel(config)
	if err != nil {
		showErrorCustom(tp.Form(), "Unable to create tunnel", err.Error())
	}

}

// Handlers

func (tp *TunnelsPage) onTunnelsViewItemActivated() {
	go func() {
		globalState, err := manager.IPCClientGlobalState()
		if err != nil || (globalState != manager.TunnelStarted && globalState != manager.TunnelStopped) {
			return
		}
		oldState, err := tp.listView.CurrentTunnel().Toggle()
		if err != nil {
			tp.Synchronize(func() {
				if oldState == manager.TunnelUnknown {
					showErrorCustom(tp.Form(), "Failed to determine tunnel state", err.Error())
				} else if oldState == manager.TunnelStopped {
					showErrorCustom(tp.Form(), "Failed to activate tunnel", err.Error())
				} else if oldState == manager.TunnelStarted {
					showErrorCustom(tp.Form(), "Failed to deactivate tunnel", err.Error())
				}
			})
			return
		}
	}()
}

func (tp *TunnelsPage) onEditTunnel() {
	tunnel := tp.listView.CurrentTunnel()
	if tunnel == nil {
		return
	}

	if config := runEditDialog(tp.Form(), tunnel); config != nil {
		go func() {
			priorState, err := tunnel.State()
			tunnel.Delete()
			tunnel.WaitForStop()
			tunnel, err2 := manager.IPCClientNewTunnel(config)
			if err == nil && err2 == nil && (priorState == manager.TunnelStarting || priorState == manager.TunnelStarted) {
				tunnel.Start()
			}
		}()
	}
}

func (tp *TunnelsPage) onAddTunnel() {
	if config := runEditDialog(tp.Form(), nil); config != nil {
		// Save new
		tp.addTunnel(config)
	}
}

func (tp *TunnelsPage) onDelete() {
	indices := tp.listView.SelectedIndexes()
	if len(indices) == 0 {
		return
	}

	var topic string
	if len(indices) > 1 {
		topic = fmt.Sprintf("%d tunnels", len(indices))
	} else {
		topic = fmt.Sprintf("‘%s’", tp.listView.model.tunnels[indices[0]].Name)
	}
	if walk.DlgCmdNo == walk.MsgBox(
		tp.Form(),
		fmt.Sprintf("Delete %s", topic),
		fmt.Sprintf("Are you sure you would like to delete %s? You cannot undo this action.", topic),
		walk.MsgBoxYesNo|walk.MsgBoxIconWarning) {
		return
	}

	selectTunnelAfter := ""
	if len(indices) < len(tp.listView.model.tunnels) {
		sort.Ints(indices)
		max := 0
		for i, idx := range indices {
			if idx+1 < len(tp.listView.model.tunnels) && (i+1 == len(indices) || idx+1 != indices[i+1]) {
				max = idx + 1
			} else if idx-1 >= 0 && (i == 0 || idx-1 != indices[i-1]) {
				max = idx - 1
			}
		}
		selectTunnelAfter = tp.listView.model.tunnels[max].Name
	}
	if len(selectTunnelAfter) > 0 {
		tp.listView.selectTunnel(selectTunnelAfter)
	}

	tunnelsToDelete := make([]manager.Tunnel, len(indices))
	for i, j := range indices {
		tunnelsToDelete[i] = tp.listView.model.tunnels[j]

	}
	go func() {
		tp.listView.SetSuspendTunnelsUpdate(true)
		var errors []error
		for _, tunnel := range tunnelsToDelete {
			err := tunnel.Delete()
			if err != nil && (len(errors) == 0 || errors[len(errors)-1].Error() != err.Error()) {
				errors = append(errors, err)
			}
		}
		tp.listView.SetSuspendTunnelsUpdate(false)
		if len(errors) > 0 {
			tp.listView.Synchronize(func() {
				if len(errors) == 1 {
					showErrorCustom(tp.Form(), "Unable to delete tunnel", fmt.Sprintf("A tunnel was unable to be removed: %s", errors[0].Error()))
				} else {
					showErrorCustom(tp.Form(), "Unable to delete tunnels", fmt.Sprintf("%d tunnels were unable to be removed.", len(errors)))
				}
			})
		}
	}()
}

func (tp *TunnelsPage) onSelectAll() {
	tp.listView.SetSelectedIndexes([]int{-1})
}

func (tp *TunnelsPage) onImport() {
	dlg := walk.FileDialog{
		Filter: "Configuration Files (*.zip, *.conf)|*.zip;*.conf|All Files (*.*)|*.*",
		Title:  "Import tunnel(s) from file...",
	}

	if ok, _ := dlg.ShowOpenMultiple(tp.Form()); !ok {
		return
	}

	tp.importFiles(dlg.FilePaths)
}

func (tp *TunnelsPage) onExportTunnels() {
	dlg := walk.FileDialog{
		Filter: "Configuration ZIP Files (*.zip)|*.zip",
		Title:  "Export tunnels to zip...",
	}

	if ok, _ := dlg.ShowSave(tp.Form()); !ok {
		return
	}

	if !strings.HasSuffix(dlg.FilePath, ".zip") {
		dlg.FilePath += ".zip"
	}

	tp.exportTunnels(dlg.FilePath)
}

func (tp *TunnelsPage) swapFiller(enabled bool) bool {
	if tp.fillerContainer.Visible() == enabled {
		return enabled
	}
	tp.SetSuspended(true)
	tp.fillerContainer.SetVisible(enabled)
	tp.currentTunnelContainer.SetVisible(!enabled)
	tp.SetSuspended(false)
	return enabled
}

func (tp *TunnelsPage) onTunnelsChanged() {
	if tp.swapFiller(tp.listView.model.RowCount() == 0) {
		tp.fillerButton.SetText("Import tunnel(s) from file")
		tp.fillerHandler = tp.onImport
	}
}

func (tp *TunnelsPage) onSelectedTunnelsChanged() {
	if tp.listView.model.RowCount() == 0 {
		return
	}
	indices := tp.listView.SelectedIndexes()
	if tp.swapFiller(len(indices) > 1) {
		tp.fillerButton.SetText(fmt.Sprintf("Delete %d tunnels", len(indices)))
		tp.fillerHandler = tp.onDelete
	}
}