<?php

namespace NoccyLabs\JEdit\Terminal;

class Terminal
{
    private static int $init = 0;

    private ?string $oldStty = null;

    private int $lines = 0;

    private int $columns = 0;

    private bool $active = false;

    public function __construct()
    {
        if (self::$init++ == 0) {
            $this->setup();
        }
    }

    public function __destruct()
    {
        if (--self::$init == 0) {
            $this->shutdown();
        }
    }

    private function setup(): void
    {
        $this->oldStty = exec("stty -g");
        exec("stty raw -echo");

        //ob_start();

        echo "\e[s"; // save cursor pos
        echo "\e[?1047h"; // alt buffer
        echo "\e[H\e[0m\e[2J"; // clear screen
        echo "\e[?7l"; // autowrap

        //ob_flush();

        $this->measureTerminal();
        pcntl_signal(SIGWINCH, $this->measureTerminal(...));

        $this->active = true;
    }

    private function measureTerminal(): void
    {
        $this->lines = intval(exec("tput lines"));
        $this->columns = intval(exec("tput cols"));
    }

    public function shutdown(): void
    {
        //ob_end_clean();
        if (!$this->active) return;

        exec("stty {$this->oldStty}");

        echo "\e[?1047l"; // main buffer
        echo "\e[u\e[?25h"; // restore cursor pos and visibility
        echo "\e[?7h"; // autowrap

        $this->active = false;
    }

    public function getSize(): array
    {
        return [ $this->columns, $this->lines ];
    }

    public function setCursor(int $column, int $row, bool $visible = false): void
    {
        if ($row > 0 && $column > 0)
            printf("\e[%d;%dH", $row, $column);
        echo "\e[?25".($visible?"h":"l");
    }

    private string $inputBuffer = '';

    public function readKey(): ?string
    {
        $r = [ STDIN ]; $w = $e = [];
        if (stream_select($r, $w, $e, 0)) {
            $read = fread(STDIN, 64);
            $this->inputBuffer .= $read;
        }
        return $this->parseInputBuffer();
    }

    private function parseInputBuffer(): ?string
    {
        if (str_starts_with($this->inputBuffer, "\e")) {
            if (strncmp($this->inputBuffer, "\e[A", 3) === 0) {
                $this->inputBuffer = mb_substr($this->inputBuffer, 3);
                return "k{UP}";
            } elseif (strncmp($this->inputBuffer, "\e[B", 3) === 0) {
                $this->inputBuffer = mb_substr($this->inputBuffer, 3);
                return "k{DOWN}";
            } elseif (strncmp($this->inputBuffer, "\e[C", 3) === 0) {
                $this->inputBuffer = mb_substr($this->inputBuffer, 3);
                return "k{RIGHT}";
            } elseif (strncmp($this->inputBuffer, "\e[D", 3) === 0) {
                $this->inputBuffer = mb_substr($this->inputBuffer, 3);
                return "k{LEFT}";
            } elseif (strncmp($this->inputBuffer, "\e[5~", 4) === 0) {
                $this->inputBuffer = mb_substr($this->inputBuffer, 4);
                return "k{PGUP}";
            } elseif (strncmp($this->inputBuffer, "\e[6~", 4) === 0) {
                $this->inputBuffer = mb_substr($this->inputBuffer, 4);
                return "k{PGDN}";
            } elseif (strncmp($this->inputBuffer, "\e\e", 2) === 0) {
                $this->inputBuffer = mb_substr($this->inputBuffer, 2);
                return chr(27);
            }
            $this->inputBuffer = mb_substr($this->inputBuffer, 1);
        }
        if (mb_strlen($this->inputBuffer) > 0) {            
            $ch = mb_substr($this->inputBuffer, 0, 1);
            // if (ord($ch) == 3) {
            //     return "k{^C}";
            // }
            $this->inputBuffer = mb_substr($this->inputBuffer, 1);
            return $ch;
        }
        return null;
    }
    
}