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

package readline

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

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

var _ = fmt.Print

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

type SyntaxHighlightFunction func(text string, x, y int) string

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

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)
}

// Actions {{{
type Action uint

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

	ActionStartKillActions
	ActionKillToEndOfLine
	ActionKillToStartOfLine
	ActionKillNextWord
	ActionKillPreviousWord
	ActionKillPreviousSpaceDelimitedWord
	ActionEndKillActions

	ActionYank
	ActionPopYank

	ActionNumericArgumentDigit0
	ActionNumericArgumentDigit1
	ActionNumericArgumentDigit2
	ActionNumericArgumentDigit3
	ActionNumericArgumentDigit4
	ActionNumericArgumentDigit5
	ActionNumericArgumentDigit6
	ActionNumericArgumentDigit7
	ActionNumericArgumentDigit8
	ActionNumericArgumentDigit9
	ActionNumericArgumentDigitMinus
)

// }}}

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 Prompt struct {
	Text   string
	Length int
}

type InputState struct {
	// Input lines
	lines []string
	// The cursor position in the text
	cursor Position
}

func (self InputState) copy() InputState {
	ans := self
	l := make([]string, len(self.lines))
	copy(l, self.lines)
	ans.lines = l
	return ans
}

type syntax_highlighted struct {
	lines                  []string
	src_for_last_highlight string
	highlighter            SyntaxHighlightFunction
	last_highlighter_name  string
}

type Readline struct {
	prompt, continuation_prompt Prompt

	mark_prompts bool
	loop         *loop.Loop
	history      *History
	kill_ring    kill_ring

	input_state InputState
	// The number of lines after the initial line on the screen
	cursor_y         int
	screen_width     int
	last_yank_extent struct {
		start, end Position
	}
	bracketed_paste_buffer strings.Builder
	last_action            Action
	history_matches        *HistoryMatches
	history_search         *HistorySearch
	keyboard_state         KeyboardState
	fmt_ctx                *markup.Context
	text_to_be_added       string
	syntax_highlighted     syntax_highlighted
}

func (self *Readline) make_prompt(text string, is_secondary bool) Prompt {
	if self.mark_prompts {
		m := PROMPT_MARK + "A"
		if is_secondary {
			m += ";k=s"
		}
		text = m + ST + text
	}
	return Prompt{Text: text, Length: wcswidth.Stringwidth(text)}
}

func New(loop *loop.Loop, r RlInit) *Readline {
	hc := r.HistoryCount
	if hc == 0 {
		hc = 8192
	}
	ans := &Readline{
		mark_prompts: !r.DontMarkPrompts, fmt_ctx: markup.New(true),
		loop: loop, input_state: InputState{lines: []string{""}}, history: NewHistory(r.HistoryPath, hc),
		syntax_highlighted: syntax_highlighted{highlighter: r.SyntaxHighlighter},
		kill_ring:          kill_ring{items: list.New().Init()},
	}
	ans.prompt = ans.make_prompt(r.Prompt, false)
	t := ""
	if r.ContinuationPrompt != "" || !r.EmptyContinuationPrompt {
		t = r.ContinuationPrompt
		if t == "" {
			t = ans.fmt_ctx.Yellow(">") + " "
		}
	}
	ans.continuation_prompt = ans.make_prompt(t, true)
	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.input_state = InputState{lines: []string{""}}
	self.last_action = ActionNil
	self.keyboard_state = KeyboardState{}
	self.history_search = nil
	self.cursor_y = 0
}

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.text_to_be_added = text
	return self.dispatch_key_action(ActionAddText)
}

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.input_state.cursor.X >= len(self.input_state.lines[self.input_state.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
}