// License: GPLv3 Copyright: 2022, Kovid Goyal, <kovid at kovidgoyal.net>

package readline

import (
	"container/list"
	"fmt"
	"strings"

	"kitty/tools/tui/loop"
	"kitty/tools/wcswidth"
)

var _ = fmt.Print

const ST = "\x1b\\"
const PROMPT_MARK = "\x1b]133;"

type RlInit struct {
	Prompt                  string
	HistoryPath             string
	HistoryCount            int
	ContinuationPrompt      string
	EmptyContinuationPrompt bool
	DontMarkPrompts         bool
}

type Position struct {
	X int
	Y int
}

func (self Position) Less(other Position) bool {
	return self.Y < other.Y || (self.Y == other.Y && self.X < other.X)
}

type Action uint

const (
	ActionNil Action = iota
	ActionBackspace
	ActionDelete
	ActionMoveToStartOfLine
	ActionMoveToEndOfLine
	ActionMoveToStartOfDocument
	ActionMoveToEndOfDocument
	ActionMoveToEndOfWord
	ActionMoveToStartOfWord
	ActionCursorLeft
	ActionCursorRight
	ActionEndInput
	ActionAcceptInput
	ActionCursorUp
	ActionHistoryPreviousOrCursorUp
	ActionCursorDown
	ActionHistoryNextOrCursorDown
	ActionHistoryNext
	ActionHistoryPrevious
	ActionHistoryFirst
	ActionHistoryLast
	ActionClearScreen
	ActionAddText
	ActionAbortCurrentLine

	ActionStartKillActions
	ActionKillToEndOfLine
	ActionKillToStartOfLine
	ActionKillNextWord
	ActionKillPreviousWord
	ActionKillPreviousSpaceDelimitedWord
	ActionEndKillActions

	ActionYank
	ActionPopYank
)

type kill_ring struct {
	items *list.List
}

func (self *kill_ring) append_to_existing_item(text string) {
	e := self.items.Front()
	if e == nil {
		self.add_new_item(text)
	}
	e.Value = e.Value.(string) + text
}

func (self *kill_ring) add_new_item(text string) {
	if text != "" {
		self.items.PushFront(text)
	}
}

func (self *kill_ring) yank() string {
	e := self.items.Front()
	if e == nil {
		return ""
	}
	return e.Value.(string)
}

func (self *kill_ring) pop_yank() string {
	e := self.items.Front()
	if e == nil {
		return ""
	}
	self.items.MoveToBack(e)
	return self.yank()
}

func (self *kill_ring) clear() {
	self.items = self.items.Init()
}

type Readline struct {
	prompt                  string
	prompt_len              int
	continuation_prompt     string
	continuation_prompt_len int
	mark_prompts            bool
	loop                    *loop.Loop
	history                 *History
	kill_ring               kill_ring

	// The number of lines after the initial line on the screen
	cursor_y     int
	screen_width int
	// Input lines
	lines []string
	// The cursor position in the text
	cursor           Position
	last_yank_extent struct {
		start, end Position
	}
	bracketed_paste_buffer strings.Builder
	last_action            Action
	history_matches        *HistoryMatches
}

func New(loop *loop.Loop, r RlInit) *Readline {
	hc := r.HistoryCount
	if hc == 0 {
		hc = 8192
	}
	ans := &Readline{
		prompt: r.Prompt, prompt_len: wcswidth.Stringwidth(r.Prompt), mark_prompts: !r.DontMarkPrompts,
		loop: loop, lines: []string{""}, history: NewHistory(r.HistoryPath, hc), kill_ring: kill_ring{items: list.New().Init()},
	}
	if r.ContinuationPrompt != "" || !r.EmptyContinuationPrompt {
		ans.continuation_prompt = r.ContinuationPrompt
		if ans.continuation_prompt == "" {
			ans.continuation_prompt = "> "
		}
	}
	ans.continuation_prompt_len = wcswidth.Stringwidth(ans.continuation_prompt)
	if ans.mark_prompts {
		ans.prompt = PROMPT_MARK + "A" + ST + ans.prompt
		ans.continuation_prompt = PROMPT_MARK + "A;k=s" + ST + ans.continuation_prompt
	}
	return ans
}

func (self *Readline) Shutdown() {
	self.history.Shutdown()
}

func (self *Readline) AddHistoryItem(hi HistoryItem) {
	self.history.add_item(hi)
}

func (self *Readline) ResetText() {
	self.lines = []string{""}
	self.cursor = Position{}
	self.cursor_y = 0
	self.last_action = ActionNil
}

func (self *Readline) ChangeLoopAndResetText(lp *loop.Loop) {
	self.loop = lp
	self.ResetText()
}

func (self *Readline) Start() {
	self.loop.SetCursorShape(loop.BAR_CURSOR, true)
	self.loop.StartBracketedPaste()
	self.Redraw()
}

func (self *Readline) End() {
	self.loop.SetCursorShape(loop.BLOCK_CURSOR, true)
	self.loop.EndBracketedPaste()
	self.loop.QueueWriteString("\r\n")
	if self.mark_prompts {
		self.loop.QueueWriteString(PROMPT_MARK + "C" + ST)
	}
}

func MarkOutputStart() string {
	return PROMPT_MARK + "C" + ST
}

func (self *Readline) Redraw() {
	self.loop.StartAtomicUpdate()
	self.RedrawNonAtomic()
	self.loop.EndAtomicUpdate()
}

func (self *Readline) RedrawNonAtomic() {
	self.redraw()
}

func (self *Readline) OnKeyEvent(event *loop.KeyEvent) error {
	err := self.handle_key_event(event)
	if err == ErrCouldNotPerformAction {
		err = nil
		self.loop.Beep()
	}
	return err
}

func (self *Readline) OnText(text string, from_key_event bool, in_bracketed_paste bool) error {
	if in_bracketed_paste {
		self.bracketed_paste_buffer.WriteString(text)
		return nil
	}
	if self.bracketed_paste_buffer.Len() > 0 {
		self.bracketed_paste_buffer.WriteString(text)
		text = self.bracketed_paste_buffer.String()
		self.bracketed_paste_buffer.Reset()
	}
	self.add_text(text)
	self.last_action = ActionAddText
	return nil
}

func (self *Readline) TextBeforeCursor() string {
	return self.text_upto_cursor_pos()
}

func (self *Readline) TextAfterCursor() string {
	return self.text_after_cursor_pos()
}

func (self *Readline) AllText() string {
	return self.all_text()
}

func (self *Readline) CursorAtEndOfLine() bool {
	return self.cursor.X >= len(self.lines[self.cursor.Y])
}

func (self *Readline) OnResize(old_size loop.ScreenSize, new_size loop.ScreenSize) error {
	self.screen_width = int(new_size.CellWidth)
	if self.screen_width < 1 {
		self.screen_width = 1
	}
	self.Redraw()
	return nil
}