<?php

class UOJRemoteProblem {
	static $providers = [
		'codeforces' => [
			'name' => 'Codeforces',
			'short_name' => 'CF',
			'url' => 'https://codeforces.com',
			'not_exists_texts' => [
				'<th>Actions</th>',
				'Statement is not available on English language',
				'ограничение по времени на тест',
			],
			'languages' => ['C', 'C++', 'C++17', 'C++20', 'Java17', 'Pascal', 'Python2', 'Python3'],
		],
		'atcoder' => [
			'name' => 'AtCoder',
			'short_name' => 'AT',
			'url' => 'https://atcoder.jp',
			'not_exists_texts' => [
				'Task not found',
				'指定されたタスクが見つかりません',
			],
			'languages' => ['C', 'C++', 'Java11', 'Python3', 'Pascal'],
		],
		'uoj' => [
			'name' => 'UniversalOJ',
			'short_name' => 'UOJ',
			'url' => 'https://uoj.ac',
			'not_exist_texts' => [
				'未找到该页面',
			],
			'languages' => ['C', 'C++03', 'C++11', 'C++', 'C++17', 'C++20', 'Python3', 'Python2.7', 'Java8', 'Java11', 'Java17', 'Pascal'],
		],
		'loj' => [
			'name' => 'LibreOJ',
			'short_name' => 'LOJ',
			'url' => 'https://loj.ac',
			'languages' => ['C', 'C++03', 'C++11', 'C++', 'C++17', 'C++20', 'Python3', 'Python2.7', 'Java17', 'Pascal'],
		],
	];

	static function getCodeforcesProblemUrl($id) {
		if (str_starts_with($id, 'GYM')) {
			return static::$providers['codeforces']['url'] . '/gym/' . preg_replace_callback('/GYM([1-9][0-9]{0,5})([A-Z][1-9]?)/', fn ($matches) => $matches[1] . '/problem/' . $matches[2], $id);
		}

		return static::$providers['codeforces']['url'] . '/problemset/problem/' . preg_replace_callback('/([1-9][0-9]{0,5})([A-Z][1-9]?)/', fn ($matches) => $matches[1] . '/' . $matches[2], $id);
	}

	static function getAtcoderProblemUrl($id) {
		return static::$providers['atcoder']['url'] . '/contests/' . preg_replace_callback('/(\w+)([a-z][1-9]?)/', function ($matches) {
			$contest = str_replace('_', '', $matches[1]);

			if (str_ends_with($matches[1], '_')) {
				return "{$contest}/tasks/{$matches[1]}{$matches[2]}";
			}

			return "{$contest}/tasks/{$matches[1]}_{$matches[2]}";
		}, $id);
	}

	static function getUojProblemUrl($id) {
		return static::$providers['uoj']['url'] . '/problem/' . $id;
	}

	static function getLojProblemUrl($id) {
		return static::$providers['loj']['url'] . '/p/' . $id;
	}

	static function getCodeforcesProblemBasicInfoFromHtml($id, $html) {
		$remote_provider = static::$providers['codeforces'];

		$html = preg_replace('/\$\$\$/', '$', $html);
		$dom = new \IvoPetkov\HTML5DOMDocument();
		$dom->loadHTML($html);

		$judgestatement = $dom->querySelector('html')->innerHTML;

		foreach ($remote_provider['not_exists_texts'] as $text) {
			if (str_contains($judgestatement, $text)) {
				return null;
			}
		}

		$statement_dom = $dom->querySelector('.problem-statement');
		$title_prefix = str_starts_with($id, 'GYM') ? 'Gym' : 'CF';
		$title = explode('. ', trim($statement_dom->querySelector('.title')->innerHTML))[1];
		$title_id = str_starts_with($id, 'GYM') ? substr($id, 3) : $id;
		$title = "【{$title_prefix}{$title_id}】{$title}";
		$time_limit = intval(substr($statement_dom->querySelector('.time-limit')->innerHTML, 53));
		$memory_limit = intval(substr($statement_dom->querySelector('.memory-limit')->innerHTML, 55));
		$difficulty = -1;

		foreach ($dom->querySelectorAll('.tag-box') as &$elem) {
			$matches = [];

			if (preg_match('/\*([0-9]{3,4})/', trim($elem->innerHTML), $matches)) {
				$difficulty = intval($matches[1]);

				break;
			}
		}

		if ($difficulty != -1) {
			$closest = null;

			foreach (UOJProblem::$difficulty as $val) {
				if ($closest === null || abs($val - $difficulty) < abs($closest - $difficulty)) {
					$closest = $val;
				}
			}

			$difficulty = $closest;
		}

		$statement_dom->removeChild($statement_dom->querySelector('.header'));
		$statement_dom->childNodes->item(0)->insertBefore($dom->createElement('h3', 'Description'), $statement_dom->childNodes->item(0)->childNodes->item(0));

		foreach ($statement_dom->querySelectorAll('.section-title') as &$elem) {
			$elem->outerHTML = '<h3>' . $elem->innerHTML . '</h3>';
		}

		$sample_input_cnt = 0;
		$sample_output_cnt = 0;

		foreach ($statement_dom->querySelectorAll('.input') as &$input_dom) {
			$sample_input_cnt++;
			$input_text = '';

			if ($input_dom->querySelector('.test-example-line')) {
				foreach ($input_dom->querySelectorAll('.test-example-line') as &$line) {
					$input_text .= HTML::stripTags($line->innerHTML) . "\n";
				}
			} else {
				$input_text = HTML::stripTags($input_dom->querySelector('pre')->innerHTML);
			}

			$input_dom->outerHTML = HTML::tag('h4', [], "Input #{$sample_input_cnt}") . HTML::tag('pre', [], HTML::tag('code', [], $input_text));
		}

		foreach ($statement_dom->querySelectorAll('.output') as &$output_dom) {
			$sample_output_cnt++;
			$output_text = '';

			if ($output_dom->querySelector('.test-example-line')) {
				foreach ($output_dom->querySelectorAll('.test-example-line') as &$line) {
					$output_text .= HTML::stripTags($line->innerHTML) . "\n";
				}
			} else {
				$output_text = HTML::stripTags($output_dom->querySelector('pre')->innerHTML);
			}

			$output_dom->outerHTML = HTML::tag('h4', [], "Output #{$sample_output_cnt}") . HTML::tag('pre', [], HTML::tag('code', [], $output_text));
		}

		return [
			'type' => 'html',
			'title' => $title,
			'time_limit' => $time_limit,
			'memory_limit' => $memory_limit,
			'difficulty' => $difficulty,
			'statement' => $statement_dom->innerHTML,
		];
	}

	static function getCodeforcesProblemBasicInfo($id) {
		$curl = new Curl();
		$curl->setUserAgent('Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.0.0 Safari/537.36 S2OJ/3.1.0');

		$res = retry_loop(function () use (&$curl, $id) {
			$curl->get(static::getCodeforcesProblemUrl($id));

			if ($curl->error) {
				return false;
			}

			return [
				'content-type' => $curl->response_headers['Content-Type'],
				'response' => $curl->response,
			];
		});

		if (!$res) return null;

		if (str_starts_with($res['content-type'], 'text/html')) {
			return static::getCodeforcesProblemBasicInfoFromHtml($id, $res['response']);
		} else if (str_starts_with($res['content-type'], 'application/pdf')) {
			$title_prefix = str_starts_with($id, 'GYM') ? 'Gym' : 'CF';
			$title_id = str_starts_with($id, 'GYM') ? substr($id, 3) : $id;
			$title = "【{$title_prefix}{$title_id}】{$title_prefix}{$title_id}";

			return [
				'type' => 'pdf',
				'title' => $title,
				'time_limit' => null,
				'memory_limit' => null,
				'difficulty' => -1,
				'pdf_data' => $res['response'],
				'statement' => HTML::tag('h3', [], '提示') .
					HTML::tag(
						'p',
						[],
						'若无法正常加载 PDF，请' .
							HTML::tag('a', ['href' => static::getCodeforcesProblemUrl($id), 'target' => '_blank'], '点此') .
							'查看原题面。'
					),
			];
		} else {
			return null;
		}
	}

	static function getAtcoderProblemBasicInfo($id) {
		$curl = new Curl();
		$curl->setUserAgent('Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.0.0 Safari/537.36 S2OJ/3.1.0');
		$curl->setCookie('language', 'en');

		$res = retry_loop(function () use (&$curl, $id) {
			$curl->get(static::getAtcoderProblemUrl($id));

			if ($curl->error) {
				return false;
			}

			return $curl->response;
		});

		if (!$res) return null;

		$dom = new \IvoPetkov\HTML5DOMDocument();
		$dom->loadHTML($res);
		$container_dom = $dom->querySelectorAll('#main-container > div.row > div.col-sm-12')->item(1);

		if (!$container_dom) return null;

		$title_dom = $container_dom->querySelector('span.h2');
		$title = '【' . strtoupper($id) . '】' . preg_replace('/([A-Z][1-9]?) - (.*)/', '$2', explode("\n", trim($title_dom->textContent))[0]);

		$limit_dom = $container_dom->querySelector('p');

		$time_limit_matches = [];
		preg_match('/Time Limit: (\d+)/', $limit_dom->textContent, $time_limit_matches);
		$time_limit = intval($time_limit_matches[1]);

		$memory_limit_matches = [];
		preg_match('/Memory Limit: (\d+)/', $limit_dom->textContent, $memory_limit_matches);
		$memory_limit = intval($memory_limit_matches[1]);

		$statement_container_dom = $container_dom->querySelector('#task-statement');
		$statement_dom = $statement_container_dom->querySelector('.lang-en');

		if (!$statement_dom) {
			$statement_dom = $statement_container_dom->querySelector('.lang-ja');
		}

		$statement_first_child = $statement_dom->querySelector('p');
		$first_child_content = trim($statement_first_child->textContent);

		if (str_starts_with($first_child_content, 'Score :') || str_starts_with($first_child_content, '配点 :')) {
			$statement_dom->removeChild($statement_first_child);
		}

		foreach ($statement_dom->querySelectorAll('var') as &$elem) {
			$html = $elem->innerHTML;

			// <sub> => _{
			$html = str_replace('<sub>', '_{', $html);

			// </sub> => }
			$html = str_replace('</sub>', '}', $html);

			// <sup> => ^{
			$html = str_replace('<sup>', '^{', $html);

			// </sup> => }
			$html = str_replace('</sup>', '}', $html);

			$elem->innerHTML = $html;
		}

		$statement = $statement_dom->innerHTML;

		// <var> => $
		$statement = str_replace('<var>', '\\(', $statement);

		// </var> => $
		$statement = str_replace('</var>', '\\)', $statement);

		return [
			'type' => 'html',
			'title' => $title,
			'time_limit' => $time_limit,
			'memory_limit' => $memory_limit,
			'difficulty' => -1,
			'statement' => $statement,
		];
	}

	static function getUojProblemBasicInfo($id) {
		$remote_provider = static::$providers['uoj'];
		$curl = new Curl();
		$curl->setUserAgent('Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.0.0 Safari/537.36 S2OJ/3.1.0');

		$res = retry_loop(function () use (&$curl, $id) {
			$curl->get(static::getUojProblemUrl($id));

			if ($curl->error) {
				return false;
			}

			return $curl->response;
		});

		if (!$res) return null;

		$dom = new \IvoPetkov\HTML5DOMDocument();
		$dom->loadHTML($res);

		$title_dom = $dom->querySelector('.page-header');
		$title_matches = [];
		preg_match('/^#[1-9][0-9]*\. (.*)$/', trim($title_dom->textContent), $title_matches);
		$title = "【{$remote_provider['short_name']}{$id}】{$title_matches[1]}";

		$statement_dom = $dom->querySelector('.uoj-article');
		$statement = HTML::tag('h3', [], '题目描述');

		foreach ($statement_dom->querySelectorAll('a') as &$elem) {
			$href = $elem->getAttribute('href');
			$href = getAbsoluteUrl($href, $remote_provider['url']);
			$elem->setAttribute('href',  $href);
		}

		$statement .= $statement_dom->innerHTML;

		return [
			'type' => 'html',
			'title' => $title,
			'time_limit' => null,
			'memory_limit' => null,
			'difficulty' => -1,
			'statement' => $statement,
		];
	}

	static function getLojProblemBasicInfo($id) {
		$remote_provider = static::$providers['loj'];
		$curl = new Curl();
		$curl->setUserAgent('Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.0.0 Safari/537.36 S2OJ/3.1.0');
		$curl->setHeader('Content-Type', 'application/json');

		$res = retry_loop(function () use (&$curl, $id) {
			$curl->post('https://api.loj.ac.cn/api/problem/getProblem', json_encode([
				'displayId' => (int)$id,
				'localizedContentsOfLocale' => 'zh_CN',
				'samples' => true,
				'judgeInfo' => true,
			]));

			if ($curl->error) {
				return false;
			}

			return $curl->response;
		});

		if (!$res) return null;

		// Convert stdClass to array
		$res = json_decode(json_encode($res), true);

		if (isset($res['error'])) return null;

		$localized_contents = $res['localizedContentsOfLocale'];
		$statement = '';

		foreach ($localized_contents['contentSections'] as $section) {
			$statement .= "\n###" . $section['sectionTitle'] . "\n\n";

			if ($section['type'] === 'Text') {
				$statement .= $section['text'] . "\n";
			} else if ($section['type'] === 'Sample') {
				// assert($res['samples'][$section['sampleId']]);
				$display_sample_id = $section['sampleId'] + 1;
				$sample = $res['samples'][$section['sampleId']];

				$statement .= "\n#### 样例输入 #{$display_sample_id}\n\n";
				$statement .= "\n```text\n{$sample['inputData']}\n```\n\n";

				$statement .= "\n#### 样例输出 #{$display_sample_id}\n\n";
				$statement .= "\n```text\n{$sample['outputData']}\n```\n\n";

				if (trim($section['text'])) {
					$statement .= "\n#### 样例解释 #{$display_sample_id}\n\n";
					$statement .= $section['text'] . "\n";
				}
			} else {
				// do nothing...
			}
		}

		return [
			'type' => 'html',
			'title' => "【{$remote_provider['short_name']}{$id}】{$localized_contents['title']}",
			'time_limit' => (float)$res['judgeInfo']['timeLimit'] / 1000.0,
			'memory_limit' => $res['judgeInfo']['memoryLimit'],
			'difficulty' => -1,
			'statement' => HTML::purifier()->purify(HTML::parsedown()->text($statement)),
		];
	}

	public static function getProblemRemoteUrl($oj, $id) {
		if ($oj === 'codeforces') {
			return static::getCodeforcesProblemUrl($id);
		} else if ($oj === 'atcoder') {
			return static::getAtcoderProblemUrl($id);
		} else if ($oj === 'uoj') {
			return static::getUojProblemUrl($id);
		} else if ($oj === 'loj') {
			return static::getLojProblemUrl($id);
		}

		return null;
	}

	// 传入 ID 需确保有效
	public static function getProblemBasicInfo($oj, $id) {
		if ($oj === 'codeforces') {
			return static::getCodeforcesProblemBasicInfo($id);
		} else if ($oj === 'atcoder') {
			return static::getAtcoderProblemBasicInfo($id);
		} else if ($oj === 'uoj') {
			return static::getUojProblemBasicInfo($id);
		} else if ($oj === 'loj') {
			return static::getLojProblemBasicInfo($id);
		}

		return null;
	}
}