package readline

import (
	"regexp"
	"strings"
)

// When the DelayedSyntaxWorker gives us a new line, we need to check if there
// is any processing to be made, that all lines match in terms of content.
func (rl *Instance) updateLine(line []rune) {
	if len(rl.currentComp) > 0 {

	} else {
		rl.line = line
	}

	rl.renderHelpers()
}

// getLine - In many places we need the current line input. We either return the real line,
// or the one that includes the current completion candidate, if there is any.
func (rl *Instance) GetLine() []rune {
	if len(rl.currentComp) > 0 {
		return rl.lineComp
	}
	return rl.line
}

func (rl *Instance) lineSuggested() (line []rune, cpos int) {
	//rl.checkCursorBounds()

	if len(rl.currentComp) > 0 {
		line = rl.lineComp
		cpos = len(rl.lineComp[:rl.pos])
	} else {
		line = rl.line
		cpos = len(rl.line[:rl.pos])
	}

	/*
	if len(rl.histSuggested) > 0 {
		line = append(line, rl.histSuggested...)
	}
	*/

	return line, cpos
}

// computeLinePos determines the X and Y coordinates of the cursor.
func (rl *Instance) computeLinePos() {
	// Use the line including any completion or line suggestion,
	// and compute buffer/cursor length. Only add a newline when
	// the current buffer does not end with one.
	line, cpos := rl.lineSuggested()
	line = append(line, '\n')

	// Get the index of each newline in the buffer.
	nl := regexp.MustCompile("\n")
	newlinesIdx := nl.FindAllStringIndex(string(line), -1)

	rl.posY = 0
	rl.fullY = 0
	startLine := 0
	cursorSet := false

	for pos, newline := range newlinesIdx {
		// Compute any adjustment in case this line must be wrapped.
		// Here, compute if line must be wrapped, to adjust posY.
		lineY := rl.realLineLen(line[startLine:newline[0]], pos)

		// All lines add to the global offset.
		rl.fullY += lineY

		switch {
		case newline[0] < cpos:
			// If we are not on the cursor line yet.
			rl.posY += lineY
		case !cursorSet:
			// We are on the cursor line, since we didn't catch
			// the first case, and that our cursor X coordinate
			// has not been set yet.
			rl.computeCursorPos(startLine, cpos, pos)
			cursorSet = true
			rl.hpos = pos
		}

		startLine = newline[1]
	}
}

// computeCursorPos computes the X/Y coordinates of the cursor on a given line.
func (rl *Instance) computeCursorPos(startLine, cpos, lineIdx int) {
	termWidth := GetTermWidth()
	cursorStart := cpos - startLine
	cursorStart += rl.getPromptPos()

	cursorY := cursorStart / termWidth
	cursorX := cursorStart % termWidth

	// The very first (unreal) line counts for nothing,
	// so by opposition all others count for one more.
	if lineIdx == 0 {
		cursorY--
	}

	// Any excess wrap means a newline.
	if cursorX > 0 {
		cursorY++
	}

	rl.posY += cursorY
	rl.posX = cursorX
}

func (rl *Instance) realLineLen(line []rune, idx int) (lineY int) {
	lineLen := getRealLength(string(line))
	termWidth := GetTermWidth()
	//lineLen += rl.Prompt.inputAt(rl)

	lineY = lineLen / termWidth
	restY := lineLen % termWidth

	// The very first line counts for nothing.
	if idx == 0 {
		lineY--
	}

	// Any excess wrap means a newline.
	if restY > 0 {
		lineY++
	}

	// Empty lines are still considered a line.
	if lineY == 0 && idx != 0 {
		lineY++
	}

	return
}

// echo - refresh the current input line, either virtually completed or not.
// also renders the current completions and hints. To be noted, the updateReferences()
// function is only ever called once, and after having moved back to prompt position
// and having printed the line: this is so that at any moment, everyone has the good
// values for moving around, synchronized with the update input line.
func (rl *Instance) echo() {

	// Then we print the prompt, and the line,
	switch {
	case rl.PasswordMask != 0:
	case rl.PasswordMask > 0:
		print(strings.Repeat(string(rl.PasswordMask), len(rl.line)) + " ")

	default:
		// Go back to prompt position, and clear everything below
		moveCursorBackwards(GetTermWidth())
		moveCursorUp(rl.posY)

		// Print the prompt
		print(string(rl.realPrompt))

		// print the line
		rl.printBuffer()

		// update cursor positions
		rl.computeLinePos()
	}

	// Update references with new coordinates only now, because
	// the new line may be longer/shorter than the previous one.
	//rl.updateReferences()
}

func (rl *Instance) insert(r []rune) {
	for {
		// I don't really understand why `0` is creaping in at the end of the
		// array but it only happens with unicode characters.
		if len(r) > 1 && r[len(r)-1] == 0 {
			r = r[:len(r)-1]
			continue
		}
		break
	}

	// We can ONLY have three fondamentally different cases:
	switch {
	// The line is empty
	case len(rl.line) == 0:
		rl.line = r

	// We are inserting somewhere in the middle
	case rl.pos < len(rl.line):
		r := append(r, rl.line[rl.pos:]...)
		rl.line = append(rl.line[:rl.pos], r...)

	// We are at the end of the input line
	case rl.pos == len(rl.line):
		rl.line = append(rl.line, r...)
	}

	rl.pos += len(r)

	// This should also update the rl.pos
	rl.updateHelpers()
}

// lineSlice returns a subset of the current input line.
func (rl *Instance) lineSlice(adjust int) (slice string) {
	switch {
	case rl.pos+adjust > len(rl.line):
		slice = string(rl.line[rl.pos:])
	case adjust < 0:
		if rl.pos+adjust < 0 {
			slice = string(rl.line[:rl.pos])
		} else {
			slice = string(rl.line[rl.pos+adjust : rl.pos])
		}
	default:
		slice = string(rl.line[rl.pos : rl.pos+adjust])
	}

	return
}

func (rl *Instance) lineCarriageReturn() {
	//rl.histSuggested = []rune{}

	// Ask the caller if the line should be accepted as is.
	if rl.AcceptMultiline(rl.GetLine()) {
		// Clear the tooltip prompt if any,
		// then go down and clear hints/completions.
		//rl.moveToLineEnd()
		//rl.Prompt.clearRprompt(rl, false)
		print("\r\n")
		print(seqClearScreenBelow)

		// Save the command line and accept it.
		//rl.writeHistoryLine()
		rl.accepted = true
		return
	}

	// If not, we should start editing another line,
	// and insert a newline where our cursor value is.
	// This has the nice advantage of being able to work
	// in multiline mode even in the middle of the buffer.
	rl.insert([]rune{'\n'})
}

func (rl *Instance) Insert(t string) {
	rl.insert([]rune(t))
}

func (rl *Instance) deleteX() {
	switch {
	case len(rl.line) == 0:
		return
	case rl.pos == 0:
		rl.line = rl.line[1:]
	case rl.pos > len(rl.line):
		rl.pos = len(rl.line)
	case rl.pos == len(rl.line):
		rl.pos--
		rl.line = rl.line[:rl.pos]
	default:
		rl.line = append(rl.line[:rl.pos], rl.line[rl.pos+1:]...)
	}

	rl.updateHelpers()
}

func (rl *Instance) deleteBackspace(forward bool) {
	switch {
	case len(rl.line) == 0:
		return
	case forward:
		rl.line = append(rl.line[:rl.pos], rl.line[rl.pos+1:]...)
	case rl.pos > len(rl.line):
		rl.backspace(forward) // There is an infite loop going on here...
	case rl.pos == len(rl.line):
		rl.pos--
		rl.line = rl.line[:rl.pos]
	default:
		rl.pos--
		rl.line = append(rl.line[:rl.pos], rl.line[rl.pos+1:]...)
	}

	rl.updateHelpers()
}

func (rl *Instance) clearLine() {
	if len(rl.line) == 0 {
		return
	}

	// We need to go back to prompt
	moveCursorUp(rl.posY)
	moveCursorBackwards(GetTermWidth())
	moveCursorForwards(rl.promptLen)

	// Clear everything after & below the cursor
	print(seqClearScreenBelow)

	// Real input line
	rl.line = []rune{}
	rl.lineComp = []rune{}
	rl.pos = 0
	rl.posX = 0
	rl.fullX = 0
	rl.posY = 0
	rl.fullY = 0

	// Completions are also reset
	rl.clearVirtualComp()
}

func (rl *Instance) printBuffer() {
	// Generate the entire line as an highlighted line,
	// and split it at each newline.
	line := string(rl.GetLine())
	lines := strings.Split(line, "\n")

	if len(line) > 0 && line[len(line)-1] == '\n' {
		lines = append(lines, "")
	}

	for i, line := range lines {
		// Indent according to the prompt.
		if i > 0 {
			moveCursorForwards(rl.getPromptPos())
		}

		if i < len(lines)-1 {
			line += "\n"
		} else {
			line += seqClearScreenBelow
		}

		print(line)
	}
}

func (rl *Instance) deleteToBeginning() {
	rl.resetVirtualComp(false)
	// Keep the line length up until the cursor
	rl.line = rl.line[rl.pos:]
	rl.pos = 0
}

func (rl *Instance) deleteToEnd() {
	rl.resetVirtualComp(false)
	// Keep everything before the cursor
	rl.line = rl.line[:rl.pos]
}

// @TODO(Renzix): move to emacs sepecific file
func (rl *Instance) emacsForwardWord(tokeniser tokeniser) (adjust int) {
	split, index, pos := tokeniser(rl.line, rl.pos)
	if len(split) == 0 {
		return
	}

	word := strings.TrimSpace(split[index])

	switch {
	case len(split) == 0:
		return
	case pos == len(word) && index != len(split)-1:
		extrawhitespace := len(strings.TrimLeft(split[index], " ")) - len(word)
		word = split[index+1]
		adjust = len(word) + extrawhitespace
	default:
		adjust = len(word) - pos
	}
	return
}

func (rl *Instance) emacsBackwardWord(tokeniser tokeniser) (adjust int) {
	split, index, pos := tokeniser(rl.line, rl.pos)
	if len(split) == 0 {
		return
	}

	switch {
	case len(split) == 0:
		return
	case pos == 0 && index != 0:
		adjust = len(split[index-1])
	default:
		adjust = pos
	}
	return
}