ExchangerExchange.php
4 years ago
FixedExchange.php
4 years ago
IndirectExchange.php
4 years ago
ReversedCurrenciesExchange.php
4 years ago
SwapExchange.php
4 years ago
IndirectExchange.php
208 lines
| 1 | <?php |
| 2 | |
| 3 | namespace Money\Exchange; |
| 4 | |
| 5 | use Money\Calculator; |
| 6 | use Money\Calculator\BcMathCalculator; |
| 7 | use Money\Calculator\GmpCalculator; |
| 8 | use Money\Calculator\PhpCalculator; |
| 9 | use Money\Currencies; |
| 10 | use Money\Currency; |
| 11 | use Money\CurrencyPair; |
| 12 | use Money\Exception\UnresolvableCurrencyPairException; |
| 13 | use Money\Exchange; |
| 14 | |
| 15 | /** |
| 16 | * Provides a way to get an exchange rate through a minimal set of intermediate conversions. |
| 17 | * |
| 18 | * @author Michael Cordingley <Michael.Cordingley@gmail.com> |
| 19 | */ |
| 20 | final class IndirectExchange implements Exchange |
| 21 | { |
| 22 | /** |
| 23 | * @var Calculator |
| 24 | */ |
| 25 | private static $calculator; |
| 26 | |
| 27 | /** |
| 28 | * @var array |
| 29 | */ |
| 30 | private static $calculators = [ |
| 31 | BcMathCalculator::class, |
| 32 | GmpCalculator::class, |
| 33 | PhpCalculator::class, |
| 34 | ]; |
| 35 | |
| 36 | /** |
| 37 | * @var Currencies |
| 38 | */ |
| 39 | private $currencies; |
| 40 | |
| 41 | /** |
| 42 | * @var Exchange |
| 43 | */ |
| 44 | private $exchange; |
| 45 | |
| 46 | /** |
| 47 | * @param Exchange $exchange |
| 48 | * @param Currencies $currencies |
| 49 | */ |
| 50 | public function __construct(Exchange $exchange, Currencies $currencies) |
| 51 | { |
| 52 | $this->exchange = $exchange; |
| 53 | $this->currencies = $currencies; |
| 54 | } |
| 55 | |
| 56 | /** |
| 57 | * @param string $calculator |
| 58 | */ |
| 59 | public static function registerCalculator($calculator) |
| 60 | { |
| 61 | if (is_a($calculator, Calculator::class, true) === false) { |
| 62 | throw new \InvalidArgumentException('Calculator must implement '.Calculator::class); |
| 63 | } |
| 64 | |
| 65 | array_unshift(self::$calculators, $calculator); |
| 66 | } |
| 67 | |
| 68 | /** |
| 69 | * {@inheritdoc} |
| 70 | */ |
| 71 | public function quote(Currency $baseCurrency, Currency $counterCurrency) |
| 72 | { |
| 73 | try { |
| 74 | return $this->exchange->quote($baseCurrency, $counterCurrency); |
| 75 | } catch (UnresolvableCurrencyPairException $exception) { |
| 76 | $rate = array_reduce($this->getConversions($baseCurrency, $counterCurrency), function ($carry, CurrencyPair $pair) { |
| 77 | return static::getCalculator()->multiply($carry, $pair->getConversionRatio()); |
| 78 | }, '1.0'); |
| 79 | |
| 80 | return new CurrencyPair($baseCurrency, $counterCurrency, $rate); |
| 81 | } |
| 82 | } |
| 83 | |
| 84 | /** |
| 85 | * @param Currency $baseCurrency |
| 86 | * @param Currency $counterCurrency |
| 87 | * |
| 88 | * @return CurrencyPair[] |
| 89 | * |
| 90 | * @throws UnresolvableCurrencyPairException |
| 91 | */ |
| 92 | private function getConversions(Currency $baseCurrency, Currency $counterCurrency) |
| 93 | { |
| 94 | $startNode = $this->initializeNode($baseCurrency); |
| 95 | $startNode->discovered = true; |
| 96 | |
| 97 | $nodes = [$baseCurrency->getCode() => $startNode]; |
| 98 | |
| 99 | $frontier = new \SplQueue(); |
| 100 | $frontier->enqueue($startNode); |
| 101 | |
| 102 | while ($frontier->count()) { |
| 103 | /** @var \stdClass $currentNode */ |
| 104 | $currentNode = $frontier->dequeue(); |
| 105 | |
| 106 | /** @var Currency $currentCurrency */ |
| 107 | $currentCurrency = $currentNode->currency; |
| 108 | |
| 109 | if ($currentCurrency->equals($counterCurrency)) { |
| 110 | return $this->reconstructConversionChain($nodes, $currentNode); |
| 111 | } |
| 112 | |
| 113 | /** @var Currency $candidateCurrency */ |
| 114 | foreach ($this->currencies as $candidateCurrency) { |
| 115 | if (!isset($nodes[$candidateCurrency->getCode()])) { |
| 116 | $nodes[$candidateCurrency->getCode()] = $this->initializeNode($candidateCurrency); |
| 117 | } |
| 118 | |
| 119 | /** @var \stdClass $node */ |
| 120 | $node = $nodes[$candidateCurrency->getCode()]; |
| 121 | |
| 122 | if (!$node->discovered) { |
| 123 | try { |
| 124 | // Check if the candidate is a neighbor. This will throw an exception if it isn't. |
| 125 | $this->exchange->quote($currentCurrency, $candidateCurrency); |
| 126 | |
| 127 | $node->discovered = true; |
| 128 | $node->parent = $currentNode; |
| 129 | |
| 130 | $frontier->enqueue($node); |
| 131 | } catch (UnresolvableCurrencyPairException $exception) { |
| 132 | // Not a neighbor. Move on. |
| 133 | } |
| 134 | } |
| 135 | } |
| 136 | } |
| 137 | |
| 138 | throw UnresolvableCurrencyPairException::createFromCurrencies($baseCurrency, $counterCurrency); |
| 139 | } |
| 140 | |
| 141 | /** |
| 142 | * @param Currency $currency |
| 143 | * |
| 144 | * @return \stdClass |
| 145 | */ |
| 146 | private function initializeNode(Currency $currency) |
| 147 | { |
| 148 | $node = new \stdClass(); |
| 149 | |
| 150 | $node->currency = $currency; |
| 151 | $node->discovered = false; |
| 152 | $node->parent = null; |
| 153 | |
| 154 | return $node; |
| 155 | } |
| 156 | |
| 157 | /** |
| 158 | * @param array $currencies |
| 159 | * @param \stdClass $goalNode |
| 160 | * |
| 161 | * @return CurrencyPair[] |
| 162 | */ |
| 163 | private function reconstructConversionChain(array $currencies, \stdClass $goalNode) |
| 164 | { |
| 165 | $current = $goalNode; |
| 166 | $conversions = []; |
| 167 | |
| 168 | while ($current->parent) { |
| 169 | $previous = $currencies[$current->parent->currency->getCode()]; |
| 170 | $conversions[] = $this->exchange->quote($previous->currency, $current->currency); |
| 171 | $current = $previous; |
| 172 | } |
| 173 | |
| 174 | return array_reverse($conversions); |
| 175 | } |
| 176 | |
| 177 | /** |
| 178 | * @return Calculator |
| 179 | */ |
| 180 | private function getCalculator() |
| 181 | { |
| 182 | if (null === self::$calculator) { |
| 183 | self::$calculator = self::initializeCalculator(); |
| 184 | } |
| 185 | |
| 186 | return self::$calculator; |
| 187 | } |
| 188 | |
| 189 | /** |
| 190 | * @return Calculator |
| 191 | * |
| 192 | * @throws \RuntimeException If cannot find calculator for money calculations |
| 193 | */ |
| 194 | private static function initializeCalculator() |
| 195 | { |
| 196 | $calculators = self::$calculators; |
| 197 | |
| 198 | foreach ($calculators as $calculator) { |
| 199 | /** @var Calculator $calculator */ |
| 200 | if ($calculator::supported()) { |
| 201 | return new $calculator(); |
| 202 | } |
| 203 | } |
| 204 | |
| 205 | throw new \RuntimeException('Cannot find calculator for money calculations'); |
| 206 | } |
| 207 | } |
| 208 |