<?php

namespace Zoomyboy\Gradient;

use GdImage;
use Illuminate\Http\UploadedFile;

class GradientImage
{
    public function generate(int $image_width, int $image_height, string $from, string $to, Degree $degree, Prop $prop = Prop::LINEAR): UploadedFile
    {
        $filename = (string) str("{$from}-{$to}.png")->replace('#', '');

        $from = $this->toRgb($from);
        $to = $this->toRgb($to);

        $image = imagecreatetruecolor($image_width, $image_height);
        $image = $this->makeGradient($image, $from, $to, $prop->calculatorCallback());
        $image = imagerotate($image, 360 - $degree->value, 0);

        imagepng($image, "/tmp/{$filename}");
        imagedestroy($image);

        return new UploadedFile("/tmp/{$filename}", $filename, 'image/png');
    }

    public function toRgb(string $hexColor): RgbColor
    {
        $hexColor = substr($hexColor, 1);

        $colors = collect(str_split($hexColor, 2))
            ->map(fn ($hex) => hexdec($hex))
            ->toArray();

        return new RgbColor(...$colors);
    }

    private function makeGradient(GdImage $image, RgbColor $from, RgbColor $to, callable $calculator): GdImage
    {
        $image_width = imagesx($image);
        $image_height = imagesy($image);

        for ($i = 0; $i < $image_height; ++$i) {
            $percent = $calculator($i, $image_height);
            $color_r = (int) floor(($from->r - $to->r) * $percent) + $to->r;
            $color_g = (int) floor(($from->g - $to->g) * $percent) + $to->g;
            $color_b = (int) floor(($from->b - $to->b) * $percent) + $to->b;

            $color = imagecolorallocate($image, $color_r, $color_g, $color_b);
            imageline($image, 0, $i, $image_width, $i, $color);
        }

        return $image;
    }
}