package main

import (
	"errors"
	"fmt"
	"strings"
	"time"

	todotxt "github.com/br0xen/go-todotxt"
	"github.com/br0xen/termbox-screen"
	"github.com/br0xen/termbox-util"
	termbox "github.com/nsf/termbox-go"
)

const MainScreenId = 0

type ViewPort struct {
	bytesPerRow  int
	numberOfRows int
	firstRow     int
}

// MainScreen holds all that's going on
type MainScreen struct {
	viewPort       ViewPort
	message        string
	messageTimeout time.Duration
	messageTime    time.Time
	messageColorBg termbox.Attribute
	messageColorFg termbox.Attribute
	mode           int
	cursor         map[string]int

	inputField *termboxUtil.InputField

	currentList   string
	currentFilter string
	activeList    *todotxt.TaskList
	displayList   *todotxt.TaskList

	undoQueue     []string
	redoQueue     []string
	backspaceDoes int
}

const (
	MainBundleListKey   = "mainscreen.list"
	MainBundleFilterKey = "mainscreen.filter"

	MainBundleListTodo = "mainscreen.list.todo"
	MainBundleListDone = "mainscreen.list.done"

	MainBackspaceNothing = iota
	MainBackspaceMain
	MainBackspaceFilter

	InputIDFilter            = "filter"
	InputIDAddTask           = "add task"
	InputIDIncompleteArchive = "archive incomplete task? (y/n)"
	InputIDUnArchiveTask     = "move task to active list? (y/n)"
)

func (screen *MainScreen) Id() int { return MainScreenId }

func (screen *MainScreen) Initialize(bundle termboxScreen.Bundle) error {
	width, height := termbox.Size()
	screen.inputField = termboxUtil.CreateInputField(0, (height - 3), width, 1, DefaultFg, DefaultBg)

	screen.cursor = make(map[string]int)
	if bundle != nil {
		if err := screen.reloadList(bundle); err != nil {
			return err
		}
		screen.inputField.SetID("")
		screen.inputField.SetBordered(false)
	}

	return nil
}
func (screen *MainScreen) ResizeScreen() { screen.Initialize(nil) }

func (screen *MainScreen) refreshList(bundle termboxScreen.Bundle) error {
	whichList := bundle.GetString(MainBundleListKey, MainBundleListTodo)
	switch whichList {
	case MainBundleListTodo:
		return app.LoadTaskList()
	case MainBundleListDone:
		return app.LoadDoneList()
	}
	return errors.New("Invalid refresh request.")
}

func (screen *MainScreen) reloadList(bundle termboxScreen.Bundle) error {
	// We add tasks to the display list using append because we want to persist task Ids
	screen.displayList = todotxt.NewTaskList()
	screen.currentList = bundle.GetString(MainBundleListKey, MainBundleListTodo)
	switch screen.currentList {
	case MainBundleListTodo:
		screen.setActiveList(app.TaskList)
		if screen.currentFilter = bundle.GetString(MainBundleFilterKey, ""); screen.currentFilter != "" {
			filteredList := app.filterList(screen.activeList, screen.currentFilter)
			for _, av := range *screen.activeList {
				for _, fv := range *filteredList {
					if av.String() == fv.String() {
						(*screen.displayList) = append(*screen.displayList, av)
						break
					}
				}
			}
		} else {
			for _, av := range *screen.activeList {
				(*screen.displayList) = append(*screen.displayList, av)
			}
		}
	case MainBundleListDone:
		if err := app.LoadDoneList(); err != nil {
			return err
		}
		screen.setActiveList(app.DoneList)
		if screen.currentFilter = bundle.GetString(MainBundleFilterKey, ""); screen.currentFilter != "" {
			filteredList := app.filterList(screen.activeList, screen.currentFilter)
			for _, av := range *screen.activeList {
				for _, fv := range *filteredList {
					if av.String() == fv.String() {
						(*screen.displayList) = append(*screen.displayList, av)
						break
					}
				}
			}
		} else {
			for _, av := range *screen.activeList {
				(*screen.displayList) = append(*screen.displayList, av)
			}
		}
	}
	if screen.cursor[screen.currentList] > len(*screen.displayList)-1 {
		screen.cursor[screen.currentList] = len(*screen.displayList) - 1
	}
	return nil
}

func (screen *MainScreen) HandleKeyEvent(event termbox.Event) int {
	if screen.inputField.GetID() != "" {
		return screen.handleInputKeyEvent(event)
	}
	if event.Ch == '?' {
		// Go to About Screen
		b := termboxScreen.Bundle{}
		if err := app.uiManager.InitializeScreen(AboutScreenId, b); err != nil {
			screen.setErrorMessage(err.Error())
		}
		return AboutScreenId
	} else if event.Key == termbox.KeyBackspace || event.Key == termbox.KeyBackspace2 {

		if screen.backspaceDoes == MainBackspaceNothing {
			if screen.currentList == MainBundleListDone {
				screen.reloadList(screen.buildBundle(MainBundleListTodo, screen.currentFilter))
			} else if screen.currentFilter != "" {
				screen.reloadList(screen.buildBundle(screen.currentList, ""))
			}
		} else if screen.backspaceDoes == MainBackspaceMain {
			screen.reloadList(screen.buildBundle(MainBundleListTodo, screen.currentFilter))
		} else if screen.backspaceDoes == MainBackspaceFilter {
			screen.reloadList(screen.buildBundle(screen.currentList, ""))
		}
		return MainScreenId

	} else if event.Key == termbox.KeySpace {
		return screen.toggleTaskComplete()

	} else if event.Ch == 'g' {
		screen.cursor[screen.currentList] = 0

	} else if event.Ch == 'G' {
		screen.cursor[screen.currentList] = len(*screen.displayList) - 1

	} else if event.Key == termbox.KeyCtrlR {
		b := screen.buildBundle(screen.currentList, screen.currentFilter)
		screen.refreshList(b)
		screen.reloadList(b)

	} else if event.Key == termbox.KeyCtrlF {
		// Jump forward half a screen
		_, h := termbox.Size()
		screen.cursor[screen.currentList] += (h / 2)
		if screen.cursor[screen.currentList] >= len(*screen.displayList) {
			screen.cursor[screen.currentList] = len(*screen.displayList) - 1
		}

	} else if event.Key == termbox.KeyCtrlB {
		// Jump back half a screen
		_, h := termbox.Size()
		screen.cursor[screen.currentList] -= (h / 2)
		if screen.cursor[screen.currentList] < 0 {
			screen.cursor[screen.currentList] = 0
		}

	} else if event.Ch == 'L' {
		return screen.toggleViewList()

	} else if event.Ch == 'a' {
		return screen.startAddNewTask()

	} else if event.Ch == 'l' || event.Key == termbox.KeyEnter || event.Key == termbox.KeyArrowRight {
		return screen.startEditTaskScreen()

	} else if event.Ch == 'j' || event.Key == termbox.KeyArrowDown {
		screen.moveCursorDown()

	} else if event.Ch == 'k' || event.Key == termbox.KeyArrowUp {
		screen.moveCursorUp()

	} else if event.Ch == 'G' {
		screen.cursor[screen.currentList] = len(*screen.displayList) - 1

	} else if event.Ch == 'g' {
		screen.cursor[screen.currentList] = 0

	} else if event.Ch == '/' {
		screen.startFilter()

	} else if event.Ch == 'D' {
		screen.confirmArchiveItem()

	} else if event.Ch == 'q' {
		return ExitScreenId
	}
	return MainScreenId
}

func (screen *MainScreen) handleInputKeyEvent(event termbox.Event) int {
	switch screen.inputField.GetID() {
	case InputIDFilter:
		if event.Key == termbox.KeyEnter {
			// Apply the filter
			filter := screen.inputField.GetValue()
			screen.inputField.SetID("")
			screen.inputField.SetValue("")
			screen.backspaceDoes = MainBackspaceFilter
			screen.reloadList(screen.buildBundle(screen.currentList, filter))
			return MainScreenId
		}
	case InputIDAddTask:
		if event.Key == termbox.KeyEnter {
			// Create the new item
			err := app.addTask(screen.inputField.GetValue())
			if err != nil {
				screen.setErrorMessage(err.Error())
			}
			screen.inputField.SetID("")
			screen.inputField.SetValue("")
			screen.reloadList(screen.buildBundle(screen.currentList, screen.currentFilter))
			return MainScreenId
		}
	case InputIDIncompleteArchive:
		if event.Ch == 'y' || event.Ch == 'Y' {
			return screen.archiveCurrentItem()
		}
		screen.inputField.SetID("")
		screen.inputField.SetValue("")
		screen.reloadList(screen.buildBundle(screen.currentList, screen.currentFilter))
		return MainScreenId
	case InputIDUnArchiveTask:
		if event.Ch == 'y' || event.Ch == 'Y' {
			screen.inputField.SetID("")
			screen.inputField.SetValue("")
			screen.reloadList(screen.buildBundle(screen.currentList, screen.currentFilter))
			return screen.unarchiveCurrentItem()
		}
		screen.inputField.SetID("")
		screen.inputField.SetValue("")
		screen.reloadList(screen.buildBundle(screen.currentList, screen.currentFilter))
		return MainScreenId
	}
	if event.Key == termbox.KeyBackspace || event.Key == termbox.KeyBackspace2 {
		if screen.inputField.GetValue() == "" {
			screen.reloadList(screen.buildBundle(screen.currentList, screen.inputField.GetValue()))
			screen.inputField.SetID("")
			screen.inputField.SetValue("")
			return MainScreenId
		}
	} else if event.Key == termbox.KeyEsc {
		screen.reloadList(screen.buildBundle(screen.currentList, screen.currentFilter))
		screen.inputField.SetID("")
		screen.inputField.SetValue("")
		return MainScreenId
	}
	screen.inputField.HandleEvent(event)
	return MainScreenId
}

func (screen *MainScreen) setActiveList(list *todotxt.TaskList) {
	screen.activeList = list
}

func (screen *MainScreen) DrawScreen() {
	_, height := termbox.Size()
	screen.viewPort.numberOfRows = height - 1
	if screen.inputField.GetID() != "" {
		screen.viewPort.numberOfRows--
	}
	screen.viewPort.firstRow = 1
	displayOffset := 0
	maxCursor := screen.viewPort.numberOfRows * 2 / 3
	if screen.cursor[screen.currentList] > maxCursor {
		displayOffset = screen.cursor[screen.currentList] - maxCursor
	}

	if screen.message == "" {
		screen.setMessageWithTimeout("Press '?' for help", -1)
	}
	screen.drawHeader()
	topId := 0
	for _, v := range *screen.displayList {
		if v.Id > topId {
			topId = v.Id
		}
	}
	padCnt := fmt.Sprintf("%d", topId)
	for k, v := range *screen.displayList {
		pad := strings.Repeat(" ", len(padCnt)-len(fmt.Sprintf("%d", v.Id)))
		useFg, useBg := DefaultFg, DefaultBg
		if k == screen.cursor[screen.currentList] {
			useFg, useBg = CursorFg, CursorBg
		}
		lineY := k + 1 - displayOffset
		if lineY > 0 && lineY < screen.viewPort.numberOfRows {
			termboxUtil.DrawStringAtPoint(pad+app.getTaskString(v), 0, lineY, useFg, useBg)
		}
	}
	screen.drawFooter()
}

func (screen *MainScreen) drawHeader() {
	width, _ := termbox.Size()
	headerString := screen.currentFilter
	if headerString == "" {
		if screen.currentList == MainBundleListTodo {
			headerString = "Todo List"
		} else if screen.currentList == MainBundleListDone {
			headerString = "Done List"
		}
	}
	spaces := strings.Repeat(" ", ((width-len(headerString))/2)+1)
	termboxUtil.DrawStringAtPoint(fmt.Sprintf("%s%s%s", spaces, headerString, spaces), 0, 0, TitleFg, TitleBg)
}

func (screen *MainScreen) drawFooter() {
	if screen.messageTimeout > 0 && time.Since(screen.messageTime) > screen.messageTimeout {
		screen.clearMessage()
	}
	width, height := termbox.Size()
	if screen.inputField.GetID() != "" {
		screen.inputField.SetX(len(screen.inputField.GetID()) + 2)
		pad := width - len(screen.inputField.GetID()+":")
		field := screen.inputField.GetID() + ":" + strings.Repeat(" ", pad)
		termboxUtil.DrawStringAtPoint(field, 0, height-2, DefaultFg, DefaultBg)
		screen.inputField.Draw()
	}
	// And the 'message'
	termboxUtil.DrawStringAtPoint(screen.message, 0, height-1, screen.messageColorFg, screen.messageColorBg)
}

func (screen *MainScreen) confirmArchiveItem() int {
	if screen.currentList != MainBundleListTodo {
		screen.inputField.SetID(InputIDUnArchiveTask)
		return MainScreenId
	}
	// Find the task under the cursor
	if screen.cursor[screen.currentList] < len(*screen.displayList) {
		t := (*screen.displayList)[screen.cursor[screen.currentList]]
		if !t.Completed {
			// Task isn't completed, verify that the user wants to archive it
			screen.inputField.SetID(InputIDIncompleteArchive)
		} else {
			return screen.archiveCurrentItem()
		}
	}
	return MainScreenId
}

func (screen *MainScreen) archiveCurrentItem() int {
	if screen.currentList != MainBundleListTodo {
		screen.setErrorMessage("Task is already archived")
		return MainScreenId
	}
	// Find the task under the cursor
	if len(*screen.displayList) > screen.cursor[screen.currentList] {
		t := (*screen.displayList)[screen.cursor[screen.currentList]]
		if err := app.archiveTask(t.Id); err != nil {
			screen.setErrorMessage(err.Error())
			return MainScreenId
		}
		// Reload the list
		b := screen.buildBundle(screen.currentList, screen.currentFilter)
		if err := screen.reloadList(b); err != nil {
			screen.setErrorMessage(err.Error())
		}
	}
	return MainScreenId
}

func (screen *MainScreen) unarchiveCurrentItem() int {
	if screen.currentList == MainBundleListTodo {
		screen.setErrorMessage("Task is not archived")
		return MainScreenId
	}
	// Find the task under the cursor
	if len(*screen.displayList) > screen.cursor[screen.currentList] {
		t := (*screen.displayList)[screen.cursor[screen.currentList]]
		if err := app.unarchiveTask(t.Id); err != nil {
			screen.setErrorMessage(err.Error())
			return MainScreenId
		}
		// Reload the list
		b := screen.buildBundle(screen.currentList, screen.currentFilter)
		if err := screen.reloadList(b); err != nil {
			screen.setErrorMessage(err.Error())
		}
	}
	return MainScreenId
}

func (screen *MainScreen) startEditTaskScreen() int {
	// Find the task under the cursor
	if len(*screen.displayList) > screen.cursor[screen.currentList] {
		t := (*screen.displayList)[screen.cursor[screen.currentList]]
		// Load the task screen with this task
		b := termboxScreen.Bundle{}
		b.SetValue(TaskBundleTaskIdKey, t.Id)
		if err := app.uiManager.InitializeScreen(TaskScreenId, b); err != nil {
			screen.setErrorMessage(err.Error())
			return MainScreenId
		}
		return TaskScreenId
	}
	return MainScreenId
}

func (screen *MainScreen) reloadCurrentView() {
	bundle := termboxScreen.Bundle{}
	bundle.SetValue(MainBundleListKey, screen.currentList)
	bundle.SetValue(MainBundleFilterKey, screen.currentFilter)
	screen.reloadList(bundle)
}

func (screen *MainScreen) toggleViewList() int {
	bundle := termboxScreen.Bundle{}
	if screen.currentList == MainBundleListTodo {
		bundle.SetValue(MainBundleListKey, MainBundleListDone)
		screen.backspaceDoes = MainBackspaceMain
	} else {
		bundle.SetValue(MainBundleListKey, MainBundleListTodo)
	}
	bundle.SetValue(MainBundleFilterKey, screen.currentFilter)
	screen.reloadList(bundle)
	return MainScreenId
}

func (screen *MainScreen) startAddNewTask() int {
	screen.inputField.SetID(InputIDAddTask)
	return MainScreenId
}

func (screen *MainScreen) toggleTaskComplete() int {
	if screen.currentList == MainBundleListDone {
		screen.setErrorMessage("Task is archived, unable to modify.")
		return MainScreenId
	}

	// Find the task under the cursor
	if len(*screen.displayList) > screen.cursor[screen.currentList] {
		t := (*screen.displayList)[screen.cursor[screen.currentList]]
		err := app.toggleTaskComplete(t.Id)
		if err != nil {
			screen.setErrorMessage(err.Error())
			return MainScreenId
		}
	}
	screen.reloadCurrentView()
	return MainScreenId
}

func (screen *MainScreen) moveCursorDown() bool {
	screen.cursor[screen.currentList]++
	if screen.cursor[screen.currentList] >= len(*screen.displayList) {
		screen.cursor[screen.currentList] = len(*screen.displayList) - 1
		return false
	}
	return true
}

func (screen *MainScreen) moveCursorUp() bool {
	screen.cursor[screen.currentList]--
	if screen.cursor[screen.currentList] < 0 {
		screen.cursor[screen.currentList] = 0
		return false
	}
	return true
}

func (screen *MainScreen) startFilter() int {
	screen.inputField.SetID(InputIDFilter)
	return MainScreenId
}

func (screen *MainScreen) setErrorMessage(msg string) {
	screen.message = " " + msg + " "
	screen.messageTime = time.Now()
	screen.messageTimeout = time.Second * 2
	screen.messageColorBg = termbox.ColorRed
	screen.messageColorFg = termbox.ColorWhite | termbox.AttrBold
}

func (screen *MainScreen) setMessage(msg string) {
	screen.message = msg
	screen.messageTime = time.Now()
	screen.messageTimeout = time.Second * 2
	screen.messageColorBg = DefaultBg
	screen.messageColorFg = DefaultFg
}

/* setMessageWithTimeout lets you specify the timeout for the message
 * setting it to -1 means it won't timeout
 */
func (screen *MainScreen) setMessageWithTimeout(msg string, timeout time.Duration) {
	screen.message = msg
	screen.messageTime = time.Now()
	screen.messageTimeout = timeout
}

func (screen *MainScreen) clearMessage() {
	screen.message = fmt.Sprintf("%d Total Tasks", len(*screen.activeList))
	screen.messageTimeout = -1
	screen.messageColorBg = DefaultBg
	screen.messageColorFg = DefaultFg
}

func (screen *MainScreen) buildBundle(list, filter string) termboxScreen.Bundle {
	bundle := termboxScreen.Bundle{}
	bundle.SetValue(MainBundleListKey, list)
	bundle.SetValue(MainBundleFilterKey, filter)
	return bundle
}