package gui

import (
	"fmt"

	"github.com/fatih/color"
	"github.com/jesseduffield/gocui"
	"github.com/jesseduffield/lazygit/pkg/theme"
	"github.com/jesseduffield/lazygit/pkg/utils"
)

// getFocusLayout returns a manager function for when view gain and lose focus
func (gui *Gui) getFocusLayout() func(g *gocui.Gui) error {
	var previousView *gocui.View
	return func(g *gocui.Gui) error {
		newView := gui.g.CurrentView()
		if err := gui.onFocusChange(); err != nil {
			return err
		}
		// for now we don't consider losing focus to a popup panel as actually losing focus
		if newView != previousView && !gui.isPopupPanel(newView.Name()) {
			if err := gui.onFocusLost(previousView, newView); err != nil {
				return err
			}
			if err := gui.onFocus(newView); err != nil {
				return err
			}
			previousView = newView
		}
		return nil
	}
}

func (gui *Gui) onFocusChange() error {
	currentView := gui.g.CurrentView()
	for _, view := range gui.g.Views() {
		view.Highlight = view == currentView
	}
	return nil
}

func (gui *Gui) onFocusLost(v *gocui.View, newView *gocui.View) error {
	if v == nil {
		return nil
	}
	if v.IsSearching() && newView.Name() != "search" {
		if err := gui.onSearchEscape(); err != nil {
			return err
		}
	}
	switch v.Name() {
	case "main":
		// if we have lost focus to a first-class panel, we need to do some cleanup
		gui.changeMainViewsContext("normal")
	case "commitFiles":
		if gui.State.MainContext != "patch-building" {
			if _, err := gui.g.SetViewOnBottom(v.Name()); err != nil {
				return err
			}
		}
	}
	gui.Log.Info(v.Name() + " focus lost")
	return nil
}

func (gui *Gui) onFocus(v *gocui.View) error {
	if v == nil {
		return nil
	}
	gui.Log.Info(v.Name() + " focus gained")
	return nil
}

type dimensions struct {
	x0 int
	x1 int
	y0 int
	y1 int
}

func (gui *Gui) getViewDimensions() map[string]dimensions {
	// things to consider:
	// current cyclable view
	// three modes: normal, squashed, portrait
	// three fullscreen modes: regular, half, full
	// half/full ignored squashed but not portrait where the orientation is just swapped
	// height (for squashing)
	// width (for portrait mode)
	// let's start by saying squashing and portrait mode are mutuall exclusive. If you're in portrait mode and you end up in a squashed state you're pretty much fucked either way.
	// having said that, half and fullscreen mode can be combined with the other two. Fullscreen is gonna be the same across all of the options. Half mode will just be split vertically rather than horizontally for

	// need

	// we'll start assuming normal mode
	// in normal mode pick the split between the main panel and the side panels, then give every cyclablable view roughly equal height.

	// the options panel has 1 height always

	// so our views are:
	// "status"
	// "files"
	// "branches"
	// "commits"
	// "stash"
	// "main"
	// "commitFiles"
	// "secondary"

	// would be good to have a way of describing this programmatically, like with html:

	// <box>

	width, height := gui.g.Size()

	main := "main"
	secondary := "secondary"
	if gui.State.Panels.LineByLine != nil && gui.State.Panels.LineByLine.SecondaryFocused {
		main, secondary = secondary, main
	}

	mainSectionChildren := []*box{
		{
			viewName: main,
			weight:   1,
		},
	}

	if gui.State.SplitMainPanel {
		mainSectionChildren = append(mainSectionChildren, &box{
			viewName: secondary,
			weight:   1,
		})
	}

	currentCyclableViewName := gui.currentCyclableViewName()

	var sideSectionChildren []*box
	if gui.State.ScreenMode == SCREEN_FULL || gui.State.ScreenMode == SCREEN_HALF {
		fullHeightBox := func(viewName string) *box {
			if viewName == currentCyclableViewName {
				return &box{
					viewName: viewName,
					weight:   1,
				}
			} else {
				return &box{
					viewName: viewName,
					size:     0,
				}
			}
		}

		sideSectionChildren = []*box{
			fullHeightBox("status"),
			fullHeightBox("files"),
			fullHeightBox("branches"),
			fullHeightBox("commits"),
			fullHeightBox("stash"),
		}
	} else if height >= 28 {
		sideSectionChildren = []*box{
			{
				viewName: "status",
				size:     3,
			},
			{
				viewName: "files",
				weight:   1,
			},
			{
				viewName: "branches",
				weight:   1,
			},
			{
				viewName: "commits",
				weight:   1,
			},
			{
				viewName: "stash",
				size:     3,
			},
		}
	} else {
		squashedHeight := 1
		if height >= 21 {
			squashedHeight = 3
		}

		squashedSidePanelBox := func(viewName string) *box {
			if viewName == currentCyclableViewName {
				return &box{
					viewName: viewName,
					weight:   1,
				}
			} else {
				return &box{
					viewName: viewName,
					size:     squashedHeight,
				}
			}
		}

		sideSectionChildren = []*box{
			squashedSidePanelBox("status"),
			squashedSidePanelBox("files"),
			squashedSidePanelBox("branches"),
			squashedSidePanelBox("commits"),
			squashedSidePanelBox("stash"),
		}
	}

	// we originally specified this as a ratio i.e. .20 would correspond to a weight of 1 against 4
	sidePanelWidthRatio := gui.Config.GetUserConfig().GetFloat64("gui.sidePanelWidth")
	// we could make this better by creating ratios like 2:3 rather than always 1:something
	mainSectionWeight := int(1/sidePanelWidthRatio) - 1
	sideSectionWeight := 1

	if gui.State.SplitMainPanel {
		mainSectionWeight = 5 // need to shrink side panel to make way for main panels if side-by-side
	}
	currentViewName := gui.currentViewName()
	if currentViewName == "main" {
		if gui.State.ScreenMode == SCREEN_HALF || gui.State.ScreenMode == SCREEN_FULL {
			sideSectionWeight = 0
		}
	} else {
		if gui.State.ScreenMode == SCREEN_HALF {
			mainSectionWeight = 1
		} else if gui.State.ScreenMode == SCREEN_FULL {
			mainSectionWeight = 0
		}
	}

	root := &box{
		direction: ROW,
		children: []*box{
			{
				direction: COLUMN,
				weight:    1,
				children: []*box{
					{
						direction: ROW,
						weight:    sideSectionWeight,
						children:  sideSectionChildren,
					},
					{
						conditionalDirection: func(width int, _height int) int {
							if width < 160 && height > 30 { // 2 80 character width panels
								return ROW
							} else {
								return COLUMN
							}
						},
						direction: COLUMN,
						weight:    mainSectionWeight,
						children:  mainSectionChildren,
					},
				},
			},
			// TODO: actually handle options here. Currently we're just hard-coding it to be set on the bottom row in our layout function given that we need some custom logic to have it share space with other views on that row.
			{
				viewName: "options",
				size:     1,
			},
		},
	}

	return gui.layoutViews(root, 0, 0, width, height)
}

func (gui *Gui) currentCyclableViewName() string {
	currView := gui.g.CurrentView()
	currentCyclebleView := gui.State.PreviousView
	if currView != nil {
		viewName := currView.Name()
		usePreviousView := true
		for _, view := range cyclableViews {
			if view == viewName {
				currentCyclebleView = viewName
				usePreviousView = false
				break
			}
		}
		if usePreviousView {
			currentCyclebleView = gui.State.PreviousView
		}
	}

	// unfortunate result of the fact that these are separate views, have to map explicitly
	if currentCyclebleView == "commitFiles" {
		return "commits"
	}

	return currentCyclebleView
}

// layout is called for every screen re-render e.g. when the screen is resized
func (gui *Gui) layout(g *gocui.Gui) error {
	g.Highlight = true
	width, height := g.Size()

	information := gui.Config.GetVersion()
	if gui.g.Mouse {
		donate := color.New(color.FgMagenta, color.Underline).Sprint(gui.Tr.SLocalize("Donate"))
		information = donate + " " + information
	}
	if gui.inDiffMode() {
		information = utils.ColoredString(fmt.Sprintf("%s %s %s", gui.Tr.SLocalize("showingGitDiff"), "git diff "+gui.diffStr(), utils.ColoredString(gui.Tr.SLocalize("(reset)"), color.Underline)), color.FgMagenta)
	} else if gui.inFilterMode() {
		information = utils.ColoredString(fmt.Sprintf("%s '%s' %s", gui.Tr.SLocalize("filteringBy"), gui.State.FilterPath, utils.ColoredString(gui.Tr.SLocalize("(reset)"), color.Underline)), color.FgRed, color.Bold)
	} else if len(gui.State.CherryPickedCommits) > 0 {
		information = utils.ColoredString(fmt.Sprintf("%d commits copied", len(gui.State.CherryPickedCommits)), color.FgCyan)
	}

	minimumHeight := 9
	minimumWidth := 10
	if height < minimumHeight || width < minimumWidth {
		v, err := g.SetView("limit", 0, 0, width-1, height-1, 0)
		if err != nil {
			if err.Error() != "unknown view" {
				return err
			}
			v.Title = gui.Tr.SLocalize("NotEnoughSpace")
			v.Wrap = true
			_, _ = g.SetViewOnTop("limit")
		}
		return nil
	}

	viewDimensions := gui.getViewDimensions()

	optionsVersionBoundary := width - max(len(utils.Decolorise(information)), 1)

	appStatus := gui.statusManager.getStatusString()
	appStatusOptionsBoundary := 0
	if appStatus != "" {
		appStatusOptionsBoundary = len(appStatus) + 2
	}

	_, _ = g.SetViewOnBottom("limit")
	_ = g.DeleteView("limit")

	textColor := theme.GocuiDefaultTextColor

	// reading more lines into main view buffers upon resize
	prevMainView, err := gui.g.View("main")
	if err == nil {
		_, prevMainHeight := prevMainView.Size()
		newMainHeight := viewDimensions["main"].y1 - viewDimensions["main"].y0 - 1
		heightDiff := newMainHeight - prevMainHeight
		if heightDiff > 0 {
			if manager, ok := gui.viewBufferManagerMap["main"]; ok {
				manager.ReadLines(heightDiff)
			}
			if manager, ok := gui.viewBufferManagerMap["secondary"]; ok {
				manager.ReadLines(heightDiff)
			}
		}
	}

	setViewFromDimensions := func(viewName string, boxName string) (*gocui.View, error) {
		dimensionsObj := viewDimensions[boxName]
		return g.SetView(
			viewName,
			dimensionsObj.x0,
			dimensionsObj.y0,
			dimensionsObj.x1,
			dimensionsObj.y1,
			0,
		)
	}

	v, err := setViewFromDimensions("main", "main")
	if err != nil {
		if err.Error() != "unknown view" {
			return err
		}
		v.Title = gui.Tr.SLocalize("DiffTitle")
		v.Wrap = true
		v.FgColor = textColor
		v.IgnoreCarriageReturns = true
	}

	secondaryView, err := setViewFromDimensions("secondary", "secondary")
	if err != nil {
		if err.Error() != "unknown view" {
			return err
		}
		secondaryView.Title = gui.Tr.SLocalize("DiffTitle")
		secondaryView.Wrap = true
		secondaryView.FgColor = textColor
		secondaryView.IgnoreCarriageReturns = true
	}

	hiddenViewOffset := 9999

	if v, err := setViewFromDimensions("status", "status"); err != nil {
		if err.Error() != "unknown view" {
			return err
		}
		v.Title = gui.Tr.SLocalize("StatusTitle")
		v.FgColor = textColor
	}

	filesView, err := setViewFromDimensions("files", "files")
	if err != nil {
		if err.Error() != "unknown view" {
			return err
		}
		filesView.Highlight = true
		filesView.Title = gui.Tr.SLocalize("FilesTitle")
		filesView.SetOnSelectItem(gui.onSelectItemWrapper(gui.onFilesPanelSearchSelect))
		filesView.ContainsList = true
	}

	branchesView, err := setViewFromDimensions("branches", "branches")
	if err != nil {
		if err.Error() != "unknown view" {
			return err
		}
		branchesView.Title = gui.Tr.SLocalize("BranchesTitle")
		branchesView.Tabs = []string{"Local Branches", "Remotes", "Tags"}
		branchesView.FgColor = textColor
		branchesView.SetOnSelectItem(gui.onSelectItemWrapper(gui.onBranchesPanelSearchSelect))
		branchesView.ContainsList = true
	}

	commitFilesView, err := setViewFromDimensions("commitFiles", "commits")
	if err != nil {
		if err.Error() != "unknown view" {
			return err
		}
		commitFilesView.Title = gui.Tr.SLocalize("CommitFiles")
		commitFilesView.FgColor = textColor
		commitFilesView.SetOnSelectItem(gui.onSelectItemWrapper(gui.onCommitFilesPanelSearchSelect))
		commitFilesView.ContainsList = true
	}

	commitsView, err := setViewFromDimensions("commits", "commits")
	if err != nil {
		if err.Error() != "unknown view" {
			return err
		}
		commitsView.Title = gui.Tr.SLocalize("CommitsTitle")
		commitsView.Tabs = []string{"Commits", "Reflog"}
		commitsView.FgColor = textColor
		commitsView.SetOnSelectItem(gui.onSelectItemWrapper(gui.onCommitsPanelSearchSelect))
		commitsView.ContainsList = true
	}

	stashView, err := setViewFromDimensions("stash", "stash")
	if err != nil {
		if err.Error() != "unknown view" {
			return err
		}
		stashView.Title = gui.Tr.SLocalize("StashTitle")
		stashView.FgColor = textColor
		stashView.SetOnSelectItem(gui.onSelectItemWrapper(gui.onStashPanelSearchSelect))
		stashView.ContainsList = true
	}

	if v, err := g.SetView("options", appStatusOptionsBoundary-1, height-2, optionsVersionBoundary-1, height, 0); err != nil {
		if err.Error() != "unknown view" {
			return err
		}
		v.Frame = false
		v.FgColor = theme.OptionsColor
	}

	if gui.getCommitMessageView() == nil {
		// doesn't matter where this view starts because it will be hidden
		if commitMessageView, err := g.SetView("commitMessage", hiddenViewOffset, hiddenViewOffset, hiddenViewOffset+10, hiddenViewOffset+10, 0); err != nil {
			if err.Error() != "unknown view" {
				return err
			}
			_, _ = g.SetViewOnBottom("commitMessage")
			commitMessageView.Title = gui.Tr.SLocalize("CommitMessage")
			commitMessageView.FgColor = textColor
			commitMessageView.Editable = true
			commitMessageView.Editor = gocui.EditorFunc(gui.commitMessageEditor)
		}
	}

	if check, _ := g.View("credentials"); check == nil {
		// doesn't matter where this view starts because it will be hidden
		if credentialsView, err := g.SetView("credentials", hiddenViewOffset, hiddenViewOffset, hiddenViewOffset+10, hiddenViewOffset+10, 0); err != nil {
			if err.Error() != "unknown view" {
				return err
			}
			_, err := g.SetViewOnBottom("credentials")
			if err != nil {
				return err
			}
			credentialsView.Title = gui.Tr.SLocalize("CredentialsUsername")
			credentialsView.FgColor = textColor
			credentialsView.Editable = true
		}
	}

	searchViewOffset := hiddenViewOffset
	if gui.State.Searching.isSearching {
		searchViewOffset = 0
	}

	// this view takes up one character. Its only purpose is to show the slash when searching
	searchPrefix := "search: "
	if searchPrefixView, err := g.SetView("searchPrefix", appStatusOptionsBoundary-1+searchViewOffset, height-2+searchViewOffset, len(searchPrefix)+searchViewOffset, height+searchViewOffset, 0); err != nil {
		if err.Error() != "unknown view" {
			return err
		}

		searchPrefixView.BgColor = gocui.ColorDefault
		searchPrefixView.FgColor = gocui.ColorGreen
		searchPrefixView.Frame = false
		gui.setViewContent(searchPrefixView, searchPrefix)
	}

	if searchView, err := g.SetView("search", appStatusOptionsBoundary-1+searchViewOffset+len(searchPrefix), height-2+searchViewOffset, optionsVersionBoundary+searchViewOffset, height+searchViewOffset, 0); err != nil {
		if err.Error() != "unknown view" {
			return err
		}

		searchView.BgColor = gocui.ColorDefault
		searchView.FgColor = gocui.ColorGreen
		searchView.Frame = false
		searchView.Editable = true
	}

	if appStatusView, err := g.SetView("appStatus", -1, height-2, width, height, 0); err != nil {
		if err.Error() != "unknown view" {
			return err
		}
		appStatusView.BgColor = gocui.ColorDefault
		appStatusView.FgColor = gocui.ColorCyan
		appStatusView.Frame = false
		if _, err := g.SetViewOnBottom("appStatus"); err != nil {
			return err
		}
	}

	informationView, err := g.SetView("information", optionsVersionBoundary-1, height-2, width, height, 0)
	if err != nil {
		if err.Error() != "unknown view" {
			return err
		}
		informationView.BgColor = gocui.ColorDefault
		informationView.FgColor = gocui.ColorGreen
		informationView.Frame = false
		gui.renderString(g, "information", information)

		// doing this here because it'll only happen once
		if err := gui.onInitialViewsCreation(); err != nil {
			return err
		}
	}
	if gui.State.OldInformation != information {
		gui.setViewContent(informationView, information)
		gui.State.OldInformation = information
	}

	if gui.g.CurrentView() == nil {
		initialView := gui.getFilesView()
		if gui.inFilterMode() {
			initialView = gui.getCommitsView()
		}
		if _, err := gui.g.SetCurrentView(initialView.Name()); err != nil {
			return err
		}

		if err := gui.switchFocus(gui.g, nil, initialView); err != nil {
			return err
		}
	}

	type listViewState struct {
		selectedLine int
		lineCount    int
		view         *gocui.View
		context      string
	}

	listViews := []listViewState{
		{view: filesView, context: "", selectedLine: gui.State.Panels.Files.SelectedLine, lineCount: len(gui.State.Files)},
		{view: branchesView, context: "local-branches", selectedLine: gui.State.Panels.Branches.SelectedLine, lineCount: len(gui.State.Branches)},
		{view: branchesView, context: "remotes", selectedLine: gui.State.Panels.Remotes.SelectedLine, lineCount: len(gui.State.Remotes)},
		{view: branchesView, context: "remote-branches", selectedLine: gui.State.Panels.RemoteBranches.SelectedLine, lineCount: len(gui.State.Remotes)},
		{view: commitsView, context: "branch-commits", selectedLine: gui.State.Panels.Commits.SelectedLine, lineCount: len(gui.State.Commits)},
		{view: commitsView, context: "reflog-commits", selectedLine: gui.State.Panels.ReflogCommits.SelectedLine, lineCount: len(gui.State.FilteredReflogCommits)},
		{view: stashView, context: "", selectedLine: gui.State.Panels.Stash.SelectedLine, lineCount: len(gui.State.StashEntries)},
		{view: commitFilesView, context: "", selectedLine: gui.State.Panels.CommitFiles.SelectedLine, lineCount: len(gui.State.CommitFiles)},
	}

	// menu view might not exist so we check to be safe
	if menuView, err := gui.g.View("menu"); err == nil {
		listViews = append(listViews, listViewState{view: menuView, context: "", selectedLine: gui.State.Panels.Menu.SelectedLine, lineCount: gui.State.MenuItemCount})
	}
	for _, listView := range listViews {
		// ignore views where the context doesn't match up with the selected line we're trying to focus
		if listView.context != "" && (listView.view.Context != listView.context) {
			continue
		}
		// check if the selected line is now out of view and if so refocus it
		listView.view.FocusPoint(0, listView.selectedLine)

		listView.view.SelBgColor = theme.GocuiSelectedLineBgColor
	}

	mainViewWidth, mainViewHeight := gui.getMainView().Size()
	if mainViewWidth != gui.State.PrevMainWidth || mainViewHeight != gui.State.PrevMainHeight {
		gui.State.PrevMainWidth = mainViewWidth
		gui.State.PrevMainHeight = mainViewHeight
		if err := gui.onResize(); err != nil {
			return err
		}
	}

	// here is a good place log some stuff
	// if you download humanlog and do tail -f development.log | humanlog
	// this will let you see these branches as prettified json
	// gui.Log.Info(utils.AsJson(gui.State.Branches[0:4]))
	return gui.resizeCurrentPopupPanel(g)
}

func (gui *Gui) onInitialViewsCreation() error {
	gui.changeMainViewsContext("normal")

	gui.getBranchesView().Context = "local-branches"
	gui.getCommitsView().Context = "branch-commits"

	return gui.loadNewRepo()
}

func max(a, b int) int {
	if a > b {
		return a
	}
	return b
}