<?php

namespace Darksparrow\DeegraphInteractions\DataStructures;

class DataURL
{
    /**
     * If a MIME type is in this array, then the data will just be URL encoded, otherwise it'll be base64 encoded.
     * @var array|string[] MIME Types.
     */
    public static array $EncodedMIMETypes = [
        "text/plain",
        "application/json",
    ];

    private ?string $Data = null;
    private ?string $MIMEType = null;

    public function __construct(string $stringRepresentation)
    {
        // Trim leading/trailing whitespace
        $stringRepresentation = trim($stringRepresentation);

        // Validate and process if it's a data URL
        if(mb_strpos($stringRepresentation, "data:") !== 0) return;

        // Remove the "data:" prefix
        $stringRepresentation = mb_substr($stringRepresentation, 5);

        if(mb_strpos($stringRepresentation, ",") === false) return;

        // Split into header and data parts
        $parts = explode(",", $stringRepresentation, 2);
        $header = $parts[0];

        // Check if the data is Base64-encoded
        if(mb_strpos($stringRepresentation, ";base64") === false)
        {
            // Extract MIME type (up to the ";base64" part) and decode the data
            $this->MIMEType = $header;
            $this->Data = urldecode($parts[1]);
            return;
        }

        // Data is URL-encoded; set MIME type and decode the data
        $this->MIMEType = explode(";", $header, 2)[0];
        $this->Data = base64_decode($parts[1]);
    }

    /**
     * Gets the raw data extracted from the data URL.
     *
     * @return string|null The raw data or null if parsing failed.
     */
    public function GetData(): ?string
    {
        return $this->Data;
    }

    /**
     * Gets the size of the raw data in bytes.
     *
     * @return int The size of the data, or 0 if data is null.
     */
    public function GetSize(): int
    {
        return $this->Data ? strlen($this->Data) : 0;
    }

    /**
     * Gets the MIME type of the data URL.
     *
     * @return string|null The MIME type or null if parsing failed.
     */
    public function GetMimeType(): ?string
    {
        return $this->MIMEType;
    }

    /**
     * Converts the object back to a valid data URL string.
     *
     * @return string The reconstructed data URL.
     */
    public function __toString()
    {
        // If data or MIME type is missing, return an empty string
        if (!$this->Data || !$this->MIMEType) return '';

        // Encode based on the MIME type
        if (in_array($this->MIMEType, self::$EncodedMIMETypes))
            return "data:{$this->MIMEType}," . urlencode($this->Data);

        // Base64-encode all other data
        return "data:{$this->MIMEType};base64," . base64_encode($this->Data);
    }
}