<?php
//计算句子相似度
require_once "../path.php";
require_once "../public/_pdo.php";

global $PDO;
PDO_Connect("sqlite:"._FILE_DB_PALI_SENTENCE_);
PDO_Execute("PRAGMA synchronous = OFF");
PDO_Execute("PRAGMA journal_mode = WAL");
PDO_Execute("PRAGMA foreign_keys = ON");
PDO_Execute("PRAGMA busy_timeout = 5000");


// 输入一个句子，输出整个句子的单词 array
function words_of_sentence(string $sent) {
	$words = preg_split("/[ \.\[\]\{\}\-,';‘’–0123456789]+/", $sent); // 去除标点、数字
	$words = array_filter($words);  // 去除空词
	$words = array_filter($words, function($item) { 
		if ($item != 'ca' && $item != 'vā' && $item != 'na') return $item; }); // 去除 ca, vā 和 na
	return $words;
}

// 采用 jaccard 相似度，考虑到圣典中的相似句单词、句式都是非常接近的
function jaccard_similarity($words_of_sent1, $words_of_sent2) {
	$intersect = count(array_intersect($words_of_sent1, $words_of_sent2));
	$union = count($words_of_sent1)+count($words_of_sent2)-$intersect;
	if ($union) {
		return $intersect / $union;
	} else {
		return 0;
	}
}

// 带顺序的 jaccard 算法，当前效果一般，TODO: 切片相同时加入得分
function ordered_jaccard_similarity($words_of_sent1, $words_of_sent2) {
	$score = 0;
	$k = min(count($words_of_sent1), count($words_of_sent2));
	for ($i=1; $i<$k; $i++) {
		$score += jaccard_similarity(
			array_slice($words_of_sent1, 0, $i),
			array_slice($words_of_sent2, 0, $i));
	}
	return $score / $k;
}

// 定义一个链表节点，方便 sim_sent_id 按照相似度插入
class sim_sent_node {
	public $id;
	public $jaccard_score;
	public $next;

	public function __construct($id = null, $jaccard_score = null, $next = null) {
		$this->id = $id;
		$this->jaccard_score = $jaccard_score;
		$this->next = $next;
	}
}

// 定义链表
class sim_sent_list {
	public $head;    // 头节点，默认一个虚头节点
	public $size;

	public function __construct() {
		$this->head = new sim_sent_node();
		$this->size = 0;
	}

	// 按照 jaccard_score 相似度插入
	public function jaccard_add($id, $jaccard_score) {
		$prev = $this->head;
		while ($prev->next != null && $prev->next->jaccard_score > $jaccard_score) {
			$prev = $prev->next;
		}
		$prev->next = new sim_sent_node($id, $jaccard_score, $prev->next);
		$this->size++;
	}

	public function get_text_list() {
		$prev = $this->head;
		if ($this->size == 0) {
			return;
		}

		$ids = "";
		while ($prev->next != null) {
			$ids = $ids.",".$prev->next->id;
			$prev = $prev->next;
		}
		$ids = substr($ids, 1); // 去掉第一个逗号
		return $ids;
	}

	public function print_list() {
		$prev = $this->head;
		if ($this->size == 0) {
			return;
		}
		while ($prev->next != null) {
			print($prev->next->id."\t".$prev->next->jaccard_score."\n");
			$prev = $prev->next;
		}
	}
}

// 将相似句列表存入数据库
function insert_similar_sent_list_into_sqlite($current_id, $text_list) {
	/* 使用这部分代码先为数据库添加一个 sim_sents 字段
	$add_column = "ALTER TABLE pali_sent ADD COLUMN sim_sents TEXT";
	$Action_add = PDO_Execute($add_column);
	$query = "PRAGMA TABLE_INFO (pali_sent)";
	$Fetch = PDO_FetchALL($query);
	print_r($Fetch);
	*/
	global $PDO;
	$Update = "UPDATE pali_sent SET sim_sents = ".$PDO->quote($text_list)." WHERE id = ".$current_id;
	$Result = PDO_Execute($Update);
	return;
}

// 预计算，存入数据库
function similar_sent_matrix($begin,$end,$begin_id=0) {
	// 按照 count = 18, 8, ..., 255 依次获得查询结果 (i-3,i+3)
	//          count = 17,16,...,7                                       (i-2,i+2)
	for ($current_count=$begin; $current_count <=$end ; $current_count++) { 
		print("单词数：".$current_count."\n");
		$current_query = "select id,text from pali_sent where count=".$current_count;
		$Current = PDO_FetchAll($current_query);
		if (count($Current)) {
			foreach($Current as $current_row) {
				$current_id = $current_row['id'];
				if($begin_id>0 && $current_count==$begin){
					if($current_id<$begin_id){
						continue;
					}
				}
				$current_sent = $current_row['text'];
				$current_words = words_of_sentence($current_sent);
				
				// 按照 count > $current_count-3 and count <$current_count+3 查询希望比较的语句
				if($current_count>17){
					$section = 3;
				}
				else if($current_count>6){
					$section = 2;
				}
				else if($current_count>3){
					$section = 1;
				}
				else {
					$section = 0;
				}
				$compare_query = "select id,text from pali_sent where count>".($current_count-$section)." and count<".($current_count+$section);
				$Compare = PDO_FetchALL($compare_query);

				$current_sim_sent_list = new sim_sent_list(); // 新建相似句链表
				foreach($Compare as $compare_row) {
					if ($current_row != $compare_row) {
						$compare_id = $compare_row['id'];
						$compare_sent = $compare_row['text'];
						$compare_words = words_of_sentence($compare_sent);

						if($current_count>3){
							$jaccard_score = jaccard_similarity($current_words, $compare_words);
						}
						else if($current_count==3 ){
							if($current_words==$compare_words){
								$jaccard_score = 1;
							}
						}
						else if($current_count==2){
							if($current_words==$compare_words){
								$jaccard_score = 1;
							}
						}
						else{
							$jaccard_score = 0;
						}
						if ($jaccard_score > 0.3) {
							$current_sim_sent_list->jaccard_add($compare_id, $jaccard_score);
						}
					}
				} // end of foreach $compare_row

				if ($current_sim_sent_list->size != 0) {
					print("update $current_count - ".$current_id."\n");
					$text_list = $current_sim_sent_list->get_text_list();
					insert_similar_sent_list_into_sqlite($current_id, $text_list);
				}
			} // end of foreach $current_row
		}
	}
	return;
}

// 实时计算相似句
function sents_similar_to_id($id) {
	$query = "SELECT count,text FROM pali_sent WHERE id=".$id;
	$Current = PDO_FetchALL($query);
	if (count($Current)) {
		foreach($Current as $current_row) {
			$current_count = $current_row['count'];
			$current_sent = $current_row['text'];
			$current_words = words_of_sentence($current_sent);
			print("current text: \n".$current_sent."\n");

			if ($current_count <= 5) {
				print("[-] too short.\n");
				return;
			}

			// 只和单词数大于 5 的比较
			$compare_query = "SELECT id,text FROM pali_sent WHERE count>5";
			$Compare = PDO_FetchALL($compare_query);

			$current_sim_sent_list = new sim_sent_list(); // 新建相似句链表
			foreach($Compare as $compare_row) {
				if ($current_row != $compare_row) {
					$compare_id = $compare_row['id'];
					$compare_sent = $compare_row['text'];
					$compare_words = words_of_sentence($compare_sent);

					$jaccard_score = jaccard_similarity($current_words, $compare_words);
					if ($jaccard_score > 0.3) {
						print("Jaccard similarity: ".$jaccard_score."\tSentence id:".$compare_id."\n");
						print("Text: \n". $compare_sent."\n");
						$current_sim_sent_list->jaccard_add($compare_id, $jaccard_score);
					}
				}
			} // end of foreach $compare_row

			if ($current_sim_sent_list->size != 0) {
				// $current_sim_sent_list->print_list();
			} else {
				print("[-]not found.\n");
			}

		} // end of foreach($Current)
	} // end of if (count($Current))
}

//$id = $argv[1];
//sents_similar_to_id($id);

	if ($argc < 3){
		echo "无效的参数 ";
		exit;
	}
	$from = (int)$argv[1];
	$to =(int)$argv[2];
	if ($argc > 3){
		$from_id = (int)$argv[3];
	}
	else{
		$from_id = 0;
	}
	if($from<2){
		$from = 2;
	}
	if($to>255){
		$to = 255;
	}
	similar_sent_matrix($from,$to,$from_id);
	echo "\n all done";
?>