<?php

namespace NoccyLabs\Shell;

/**
 * This is a readline-like implementation in pure PHP.
 *
 */
class LineRead
{

    const STATE_IDLE = 0;
    const STATE_READ = 1;

    protected $state = self::STATE_IDLE;
    
    protected $prompt = "cmd:>";
    
    protected $buffer = null;

    protected $history = [];

    protected $stashedBuffer = null;
    
    protected $posHistory = 0;
    
    protected $posCursor = 0;
    
    protected $posScroll = 0;
    
    protected $termWidth = 0;
    
    protected $sttyOld;

    protected $commandStyle;
    
    protected $promptStyle;

    public function __construct()
    {
        stream_set_blocking(STDIN, false);
        $this->sttyOld = trim(exec('stty -g'));
        exec('stty raw -echo opost onlret'); // isig');
    }
    
    public function __destruct()
    {
        exec('stty '.$this->sttyOld);
    }

    public function update()
    {
        if ($this->state == self::STATE_IDLE) {
            $this->state = self::STATE_READ;
            $this->redraw();
        }
        $buffer = $this->handleInput();
        return $buffer;
    }

    public function erase()
    {
        fprintf(STDOUT, "\r\e[0m\e[2K");
    }

    public function redraw()
    {
        $prompt = $this->prompt;
        $buffer = $this->buffer;

        if ($this->posCursor > strlen($this->buffer)) {
            $this->posCursor = strlen($this->buffer);
        }

        $cursor = strlen($this->prompt) + 2 + $this->posCursor - $this->posScroll;
        
        $endStyle = "\e[0m";
        
        fprintf(STDOUT, "\r\e[2K%s %s\e[%dG{$endStyle}", ($this->promptStyle)($prompt), ($this->commandStyle)($buffer), $cursor);
    }
    
    protected function styleToAnsi($style)
    {
        if (!$style) {
            return;
        }
        return "\e[0;".$style."m";
    }
    
    protected function handleInput()
    {
        static $keyBuffer;
        $readBuf = fread(STDIN, 32);
        $keyBuffer .= $readBuf;
        $update = false;
        $returnBuffer = null;
        while (strlen($keyBuffer)>0) {
            if ($keyBuffer[0] == "\e") {
                if (strlen($keyBuffer)==1) {
                    $keyBuffer = "";
                    return "\e";
                }
                if ($keyBuffer[1] == "[") {
                    $ctrlChar = substr($keyBuffer, 0,3);
                    $keyBuffer = substr($keyBuffer, 3);
                    $this->parseControlCode($ctrlChar);
                }
            } elseif ($keyBuffer[0]=="\x03") {
                $this->posCursor = 0;
                $this->buffer = null;
                fprintf(STDOUT, "\r\n");
                return $keyBuffer[0];
            } else {
                $keyChar = $keyBuffer[0];
                $keyCode = ord($keyChar);
                $keyBuffer = substr($keyBuffer, 1);
                if (($keyCode >= 32) && ($keyCode < 127)) {
                    $edBuffer = substr($this->buffer, 0, $this->posCursor) . $keyChar . substr($this->buffer, $this->posCursor);
                    $this->posCursor++;
                    $this->buffer = $edBuffer;
                    $update = true;
                } elseif ($keyCode == 127) {
                    if ($this->posCursor > 0) {
                        $this->posCursor--;
                        $edBuffer = substr($this->buffer, 0, $this->posCursor) . substr($this->buffer, $this->posCursor+1);
                        $this->buffer = $edBuffer;
                        $update = true;
                    }
                } elseif ($keyCode == 13) {
                    $returnBuffer = $this->buffer;
                    array_unshift($this->history, $this->buffer);
                    $this->buffer = null;
                    $this->posCursor = 0;
                    $this->posHistory = 0;
                    printf("\n\r");
                    $this->state = self::STATE_IDLE;
                }
            }
        }
        if ($update) {
            $this->redraw();
        }
        return $returnBuffer;
    }
    
    protected function parseControlCode($code)
    {
        switch ($code) {
            case "\e[D":
                $this->posCursor = max($this->posCursor-1,0);
                $this->redraw();
                break;
            case "\e[C":
                $this->posCursor = min($this->posCursor+1,strlen($this->buffer));
                $this->redraw();
                break;
            case "\e[H":
                $this->posCursor = 0;
                $this->redraw();
                break;
            case "\e[F":
                $this->posCursor = strlen($this->buffer);
                $this->redraw();
                break;
            case "\e[A": // up
                if ($this->posHistory == 0) {
                    $this->stashedBuffer = $this->buffer;
                }
                if ($this->posCursor == strlen($this->buffer)) {
                    $this->posCursor = -1;
                }
                if ($this->posHistory < count($this->history)) {
                    $this->posHistory++;
                    $this->buffer = $this->history[$this->posHistory-1];
                }
                if ($this->posCursor == -1) {
                    $this->posCursor = strlen($this->buffer);
                }
                $this->redraw();
                break;
            case "\e[B": // down
                if ($this->posCursor == strlen($this->buffer)) {
                    $this->posCursor = -1;
                }
                if ($this->posHistory > 1) {
                    $this->posHistory--;
                    $this->buffer = $this->history[$this->posHistory-1];
                } elseif ($this->posHistory > 0) {
                    $this->posHistory--;
                    $this->buffer = $this->stashedBuffer;
                }
                if ($this->posCursor == -1) {
                    $this->posCursor = strlen($this->buffer);
                }
                $this->redraw();
                break;
            default:
                fprintf(STDERR, "\n%s\n", substr($code,1));
        }
    }
    
    public function setCommandStyle($style)
    {
        $this->commandStyle = $style;
    }

    public function setPromptText($prompt)
    {
        $this->prompt = $prompt;
    }

    public function setPromptStyle($style)
    {
        $this->promptStyle = $style;
    }

}