├── README.md
└── algorithm.php


/README.md:
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1 | # PHP-P2P-Algorithm
2 | 金融P2P常见还款算法
3 | 


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/algorithm.php:
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  1 | <?php
  2 | 
  3 | /**
  4 |  * 金融P2P融资贷款相关算法类
  5 |  * @author xiebin
  6 |  * @version 1.0
  7 |  */
  8 | class Algorithm
  9 | {
 10 | 
 11 |     /**
 12 |      * 根据借款方式计算对应期数的应还本金和利息
 13 |      * @param int $account 借款金额
 14 |      * @param double $year_apr 借款年利率
 15 |      * @param int $month_times 借款天数(目前只支持30的倍数)
 16 |      * @param string $borrow_style 还款方式
 17 |      * @param int $borrow_time 借款时间
 18 |      * @param string $type all=返回一次性还款数据,留空为返回还款每月还款详细数据
 19 |      * @return array|bool|string
 20 |      * @throws Exception
 21 |      */
 22 |     public function EqualInterest($account, $year_apr, $month_times, $borrow_style, $borrow_time = 0, $type = '')
 23 |     {
 24 |         if (intval($borrow_time) == 0) {
 25 |             $borrow_time = $_SERVER['REQUEST_TIME'];//获取当前请求时间
 26 |         }
 27 |         if (intval($month_times) % 30 != 0) { //目前只支持30的倍数
 28 |             return array();
 29 |         }
 30 |         // y：月 | x：利息 | b：本金 | e：到期
 31 |         switch ($borrow_style) {
 32 |             case 'yxb': // 按月等额本息
 33 |                 return self::EqualMonth($account, $year_apr, $month_times, $borrow_style, $borrow_time, $type);
 34 |             case 'yx_eb': // 按月付息到期还本
 35 |                 return self::EqualEndMonth($account, $year_apr, $month_times, $borrow_style, $borrow_time, $type);
 36 |             case 'ebx': // 到期还本付息
 37 |                 return self::EqualEnd($account, $year_apr, $month_times, $borrow_style, $borrow_time, $type);
 38 |             default:
 39 |                 return 'not_found';
 40 |         }
 41 |     }
 42 | 
 43 |     // 	等额本息法
 44 |     // 	贷款本金×月利率×（1+月利率）还款月数/[（1+月利率）还款月数-1]
 45 |     // 	a*[i*(1+i)^n]/[(1+I)^n-1]
 46 |     // 	（a×i－b）×（1＋i）
 47 |     private function EqualMonth($account, $year_apr, $month_times, $borrow_style, $borrow_time, $type, $profit_fee_rate)
 48 |     {
 49 |         $times = ($month_times < 30) ? 1 : $month_times / 30;
 50 |         $mrate = $year_apr / 100 / 12;
 51 |         $trate = pow(1 + $mrate, $times);
 52 |         $monthly_repayment = round(($account * $mrate * $trate) / ($trate - 1), 2);
 53 |         $repayment_account = round($monthly_repayment * $times, 2);
 54 | 
 55 |         // 计算每月利息
 56 |         $_result = array();
 57 |         $mcapital = $minterest = $scapital = 0; //每期本金、每期利息、总还款本金
 58 |         $surplus = $account; //剩余本金
 59 |         $tProfitFee = 0; //总手续费
 60 |         for ($i = 0; $i < $times; $i++) {
 61 |             $_result[$i]['profit_fee'] = round($surplus * ($profit_fee_rate / 12), 2);
 62 |             $tProfitFee += $_result[$i]['profit_fee'];
 63 | 
 64 |             $minterest = round($surplus * $mrate, 2);
 65 |             $mcapital = round($monthly_repayment - $minterest, 2);
 66 |             $_result[$i]['repayment_account'] = $monthly_repayment;
 67 | 
 68 |             //@todo 等额本息新算法计算还款时间
 69 |             $_result[$i]['repayment_time'] = $this->getRepamentTime($borrow_time, $i, 'yxb');
 70 |             $_result[$i]['interest'] = $minterest;
 71 |             $_result[$i]['capital'] = $mcapital;
 72 |             $surplus = $surplus - $mcapital;
 73 | 
 74 |             $scapital += $mcapital;
 75 |             //最后一期平账
 76 |             if ($i + 1 == $times) {
 77 |                 $_result[$i]['capital'] = round($mcapital + ($account - $scapital), 2);
 78 |                 $_result[$i]['interest'] = round($minterest + ($scapital - $account), 2);
 79 |             }
 80 |         }
 81 |         // 返回总数据
 82 |         if ($type == "all") {
 83 |             return array(
 84 |                 'repayment_account' => $repayment_account,
 85 |                 'monthly_repayment' => $monthly_repayment,
 86 |                 'month_apr' => round($year_apr / 12, 2),
 87 |                 'profit_fee' => $tProfitFee,
 88 |             );
 89 |         }
 90 |         return $_result;
 91 |     }
 92 | 
 93 |     /**
 94 |      * 按月付息到期还本
 95 |      * @param int $account 借款金额
 96 |      * @param double $year_apr 借款年利率
 97 |      * @param int $month_times 借款天数(目前只支持30的倍数)
 98 |      * @param int $borrow_style 还款方式
 99 |      * @param int $borrow_time 借款时间
100 |      * @param string $type all=返回一次性还款数据,留空为返回还款每月还款详细数据
101 |      * @return Array
102 |      */
103 |     private function EqualEndMonth($account, $year_apr, $month_times, $borrow_style, $borrow_time, $type)
104 |     {
105 |         $times = ($month_times < 30) ? 1 : $month_times / 30;
106 |         $tInterest = ceil($account * $times * ($year_apr / 12)) / 100;
107 |         $interest = round($tInterest / $times, 2);
108 |         $tAccount = $tInterest + $account;
109 |         // 返回总数据
110 |         if ($type == "all") {
111 |             return array(
112 |                 'repayment_account' => $tAccount,
113 |                 'monthly_repayment' => $interest,
114 |                 'month_apr' => round($year_apr / 12, 2),
115 |             );
116 |         }
117 |         // 计算每月利息
118 |         $_result = array();
119 |         // 本金
120 |         for ($i = 0; $i < $times; $i++) {
121 |             $_result[$i]['repayment_account'] = $interest;
122 |             //@todo 按月付息到期还本新算法计算还款时间
123 |             $_result[$i]['repayment_time'] = $this->getRepamentTime($borrow_time, $i, 'yx_eb');
124 |             $_result[$i]['interest'] = $interest;
125 |             $_result[$i]['capital'] = 0;
126 |             if ($i + 1 == $times) {
127 |                 $_result[$i]['capital'] = $account;
128 |                 $_result[$i]['repayment_account'] = $account + $tInterest - $interest * ($times - 1);
129 |                 $_result[$i]['interest'] = $tInterest - $interest * ($times - 1);
130 |             }
131 |         }
132 |         return $_result;
133 |     }
134 | 
135 |     /**
136 |      * 到期还本付息
137 |      * @param int $account 借款金额
138 |      * @param double $year_apr 借款年利率
139 |      * @param int $month_times 借款天数(目前只支持30的倍数)
140 |      * @param int $borrow_style 还款方式
141 |      * @param int $borrow_time 借款时间
142 |      * @param string $type all=返回一次性还款数据,留空为返回还款每月还款详细数据
143 |      * @return Array
144 |      */
145 |     private function EqualEnd($account, $year_apr, $month_times, $borrow_style, $borrow_time, $type)
146 |     {
147 | 
148 |         $times = ($month_times < 30) ? 1 : $month_times / 30;
149 |         $tInterest = ceil($account * $times * ($year_apr / 12)) / 100;
150 |         $interest = round($tInterest / $times, 2);
151 |         $tAccount = $tInterest + $account;
152 |         // 返回总数据
153 |         if ($type == "all") {
154 |             return array(
155 |                 'repayment_account' => $tAccount,
156 |                 'monthly_repayment' => $tAccount,
157 |                 'month_apr' => round($year_apr / 12, 2),
158 |             );
159 |         }
160 |         $_result = array();
161 |         $_result['repayment_account'] = $tAccount;
162 |         if ($month_times % 30 == 0) {
163 |             $month_times = ceil($month_times / 30) - 1;
164 |             //@todo 到期还本付息新算法计算还款时间
165 |             $_result['repayment_time'] = $this->getRepamentTime($borrow_time, $month_times, 'ebx');
166 |         } else {
167 |             //@todo 到期还本付息新算法计算还款时间
168 |             $time = $this->formatTime($borrow_time);
169 |             $_result['repayment_time'] = strtotime($month_times . ' day', $time);
170 |         }
171 |         $_result['interest'] = $tInterest;
172 |         $_result['capital'] = $account;
173 |         return array($_result);
174 |     }
175 | 
176 |     /**
177 |      * 根据放款时间获取具体期数还款截止时间
178 |      * @todo 新规则还款时间精确到天，解决30号、31号、1号时间问题
179 |      * @param int $debitTime 放款时间
180 |      * @param int $order 期数
181 |      * @param int $borrowStyle 融资还款方式 [yxb按月等额本息 | yx_eb按月付息到期还本 | ebx到期还本付息 | jx_eb按季付息到期还本]
182 |      * @author xiebin
183 |      */
184 |     function getRepamentTime($debitTime, $order, $borrowStyle)
185 |     {
186 |         $repayment_time = 0;
187 |         if ("yxb" == $borrowStyle || "yx_eb" == $borrowStyle) {
188 |             $repayment_time = $this->formatTime($debitTime, $order + 1);
189 |         } elseif ("ebx" == $borrowStyle) {
190 |             $repayment_time = $this->formatTime($debitTime, $order + 1);
191 |         } elseif ("jx_eb" == $borrowStyle) {
192 |             $repayment_time = $this->formatTime($debitTime, ($order + 1) * 3);
193 |         }
194 |         return $repayment_time;
195 |     }
196 | 
197 |     /**
198 |      * 格式化时间并判断
199 |      * @param int $time 时间戳
200 |      * @param int $order 期数［取值范围1-12］
201 |      * @author xiebin
202 |      */
203 |     function formatTime($time, $order = 1)
204 |     {
205 |         //格式化时间并判断
206 |         list($y, $m, $d, $h, $i, $s) = explode(' ', date('Y m d H i s', $time));
207 |         if ($d == 30 || $d == 31) { //如果是30号或者31号放款
208 |             /**
209 |              * @todo 解决还款计划2月跨年问题
210 |              */
211 |             $diff = intval(($m + $order) / 12);
212 |             $month = ($m + $order) > 12 ? ($m + $order - $diff * 12) : $m + $order; //获取月份
213 |             if ($month == 2) { //如果是2月
214 |                 $day = date('t', mktime(0, 0, 0, 2, 1, $y + $diff)); //获取2月天数
215 |                 $timestamp = mktime(23, 59, 59, 2, $day, $y + $diff);
216 |             } else {
217 |                 $timestamp = mktime(0, 0, 0, $m + $order, $d, $y) - 1;
218 |             }
219 |         } else {
220 |             $timestamp = mktime(0, 0, 0, $m + $order, $d, $y) - 1;
221 |         }
222 |         return $timestamp;
223 |     }
224 | }


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