<?php

session_start();

// Global variables

$_dr = $_SERVER['DOCUMENT_ROOT'];
// TODO: Make configurable in .ini

// Actual filesystem
$GLOBALS['path_root'] = '/srv/http/boorein';
$GLOBALS['path_media'] = $GLOBALS['path_root'] . '/media';
$GLOBALS['path_mediadb'] = $GLOBALS['path_root'] . '/media.db';
// Uri addressed
$GLOBALS['base_root'] =
  $_SERVER['REQUEST_SCHEME'] . '://' . $_SERVER['HTTP_HOST'];
$GLOBALS['base_media'] = 'media';


header('Content-Type: application/json');

// ----- ROUTER -----
(match ([$_SERVER['DOCUMENT_URI'], $_SERVER['REQUEST_METHOD']]) {
  ['/item',   'POST'] => post_item(),
  ['/item',   'GET']  => get_item(),
    //['/search', 'GET']  => get_search(),
  default  => Json::error('Not implemented')
})->die();


function get_item()
{
  $id = $_GET['q'] ?? false;
  if (!$id) Json::error('ID not specified')->die();

  $media_db = new MediaDB();

  $item = Item::load($media_db, $id);

  if ($item === null) {
    Json::error('No item was found with the given ID')->die();
  }

  return Json::new($item->getUri());
}

function post_item()
{
  // The checks are performed internally
  $item = Item::upload($_FILES['file']);

  return Json::new([
    'type' => 'success',
    'id'   => $item->getHash(),
    'link' => $item->getUri(),
  ]);
};

class MediaDB
{
  private $handler;
  private bool $finished = false;
  private array $lines = [];

  public function __construct()
  {
    // Just initialize the file handler
    $this->handler = fopen($GLOBALS['path_mediadb'], 'r');
    if ($this->handler === false)
      Json::error('Error opening media DB');
  }

  private function getLine(): ?array
  {
    $ret = fgetcsv($this->handler, 0, ' ');
    if ($ret === false)
      return null;

    return $ret;
  }

  public function map(callable $func)
  {
    // First read from what's already in memory
    foreach ($this->lines as $i_line) {
      if ($func($i_line) === false) return;
    }

    // REVIEW: Maybe this isn't needed cuz the while would be as eficient
    //         anyway?

    // If we already got to the end, there's no sense in carrying on
    if ($this->finished) return;

    // If we run out, read from the file and append to array so the next lookup
    // is fast
    while ($line = $this->getLine()) {
      $this->lines[] = $line;

      if ($func($line) === false) return;
    }

    // Set the flag so we don't reach this point two times
    $this->finished = true;
  }
}

class Item
{
  // TODO: Change to id here in all occurrences
  private string $hash;
  private string $extension;
  private array $tags = [];

  public static function load(MediaDB $db, string $id): ?Item
  {
    $ret = null;

    $db->map(function ($line) use (&$ret, $id) {
      if ($line[0] == $id) {
        $ret = new Item();
        $ret->hash = array_shift($line);
        $ret->tags = $line;
        $ret->extensionFromTags();

        return true;
      }

      return false;
    });

    return $ret;
  }


  // ::upload() requires the PHP file upload ARRAY from $_FILES
  public static function upload(array $php_file): Item
  {
    $from_path = $php_file['tmp_name'] ?? null;

    // --- CHECKS ---
    if (!is_string($from_path))
      Json::error('Passed invalid upload structure')->die();
    if (!is_uploaded_file($from_path))
      Json::error('Trying to upload illegal or non-existent file')->die();

    // --- INITIALIZE ---
    $ret = new Item();
    $ret->hash = hash_file('sha256', $from_path);
    $ret->extensionFromUpload($php_file);

    // --- ACTUALLY GRAB FILE ---
    $new_path = $ret->getPath();
    if (file_exists($new_path))
      Json::error('File already exists')->die();
    if (!move_uploaded_file($from_path, $new_path))
      Json::error('Failed to move uploaded file')->die();

    return $ret;
  }

  private function extensionFromTags()
  {
    foreach ($this->tags as $i_tag) {
      $parts = explode(':', $i_tag);
      if ($parts[0] == 'format') {
        $this->extension = $parts[1];
        return;
      }
    }
  }

  // Assumes is_uploaded_file has been done
  private function extensionFromUpload(array $php_file)
  {
    $path = $php_file['tmp_name'] ?? false;
    $name = $php_file['name'] ?? null;

    // Try to get extension from mimetype
    $ext = (new finfo(FILEINFO_EXTENSION))->file($path);

    // REVIEW: Maybe change it so it doesn't have to be separated like this but
    //         do somethign like ['mime/type', null] be equivalent to this?
    if (array_search($ext, ['webp', 'png', 'jpeg']) !== false) {
      $this->extension = $ext;
      return;
    }

    // If it doesn't work, try to figure it out from the original extension
    if ($ext == '???') {
      // We mustn't accept everything straight away, so we're only accepting
      // mime-type and original extension combinations that make sense
      $whitelist = [
        ['application/zip', 'kra'],
        ['application/zip', 'krz'],
      ];

      // NOTE: The original extension has to be grabbed from the original name
      $mime = mime_content_type($path);
      $ext  = pathinfo($name, PATHINFO_EXTENSION);

      if (array_search([$mime, $ext], $whitelist) !== false) {
        $this->extension = $ext;
        return;
      }
    }

    Json::error('File mime-type and or extension not allowed.')->die();
  }

  public function getHash(): string
  {
    return $this->hash;
  }
  public function getExtension(): string
  {
    return $this->extension;
  }

  public function getPath(bool $absolute = false): string
  {
    return sprintf(
      '%s/%s.%s',
      $GLOBALS[$absolute ? 'path_media' : 'path_media'],
      $this->hash,
      $this->extension
    );
  }
  public function getUri(): string
  {
    // TODO: Implement relative
    return sprintf(
      '%s/%s/%s.%s',
      $GLOBALS['base_root'],
      $GLOBALS['base_media'],
      $this->hash,
      $this->extension,
    );
  }
}

class Json
{
  function __construct(
    private mixed $struct
  ) {
    $this->struct = $struct;
  }

  public static function new(mixed $struct): Json
  {
    return new Json($struct);
  }

  public static function error(mixed $msg): Json
  {
    return new Json([
      'type' => 'error',
      'msg' => $msg,
    ]);
  }

  public function die()
  {
    print(json_encode($this->struct));
    die();
  }
}