Merge pull request #16 from gauravmak/from_string_implementation

Money instance creation from a formatted string

README.md

@@ -143,7 +143,7 @@ $money->decimals(); // 100.0
 
 ### Formatting money
 
-You can format money using the `->formatted()` method:
+You can format money using the `->formatted()` method. It takes [display decimals](#display-decimals) into consideration.
 
 ```php
 $money = Money::fromDecimal(40.25, USD::class);
@@ -166,6 +166,33 @@ $money = Money::fromDecimal(40.25, USD::class);
 $money->formatted(['decimalSeparator' => ',', 'prefix' => '$ ', 'suffix' => ' USD']);
 ```
 
+There's also `->rawFormatted()` if you wish to use [math decimals](#math-decimals) instead of [display decimals](#display-decimals).
+```php
+$money = Money::new(123456, CZK::class);
+$money->rawFormatted(); // 1 234,56 Kč
+```
+
+Converting the formatted value back to the `Money` instance is also possible. The package tries to extract the currency from the provided string:
+```php
+$money = money(1000);
+$formatted = $money->formatted(); // $10.00
+$fromFormatted = Money::fromFormatted($formatted);
+$fromFormatted->is($money); // true
+```
+
+If you had passed overrides while [formatting the money instance](#formatting-money), the same can passed to this method.
+```php
+$money = money(1000);
+$formatted = $money->formatted(['prefix' => '$ ', 'suffix' => ' USD']); // $ 10.00 USD
+$fromFormatted = Money::fromFormatted($formatted, USD::class, ['prefix' => '$ ', 'suffix' => ' USD']);
+$fromFormatted->is($money); // true
+```
+
+Notes:
+1) If currency is not specified and none of the currencies match the prefix and suffix, an exception will be thrown.
+2) If currency is not specified and multiple currencies use the same prefix and suffix, an exception will be thrown.
+3) `fromFormatted()` misses the cents if the [math decimals](#math-decimals) are greater than [display decimals](#display-decimals).
+
 ### Rounding money
 
 Some currencies, such as the Czech Crown (CZK), generally display final prices in full crowns, but use cents for the intermediate math operations. For example:
@@ -414,7 +441,7 @@ For the Czech Crown (CZK), the display decimals will be `0`, but the math decima
 
 For the inverse of what was just explained above, you can use the `rawFormatted()` method. This returns the formatted value, **but uses the math decimals for the display decimals**. Meaning, the value in the example above will be displayed including cents:
 ```php
-money(123456, new CZK)->rawFormatted(); // 1 235,56 Kč
+money(123456, new CZK)->rawFormatted(); // 1 234,56 Kč
 ```
 
 This is mostly useful for currencies like the Czech Crown which generally don't use cents, but **can** use them in specific cases.

src/Exceptions/CannotExtractCurrencyException.php

@@ -0,0 +1,15 @@
+<?php
+
+declare(strict_types=1);
+
+namespace ArchTech\Money\Exceptions;
+
+use Exception;
+
+class CannotExtractCurrencyException extends Exception
+{
+    public function __construct(string $message)
+    {
+        parent::__construct($message);
+    }
+}

src/Money.php

@@ -36,7 +36,7 @@ final class Money implements JsonSerializable, Arrayable, Wireable
     public static function fromDecimal(float $decimal, Currency|string $currency = null): self
     {
         return new static(
-            (int) round($decimal * 10 ** currency($currency)->mathDecimals()),
+            (int) round($decimal * pow(10, currency($currency)->mathDecimals())),
             currency($currency)
         );
     }
@@ -154,7 +154,7 @@ final class Money implements JsonSerializable, Arrayable, Wireable
     /** Get the decimal representation of the value. */
     public function decimal(): float
     {
-        return $this->value / 10 ** $this->currency->mathDecimals();
+        return $this->value / pow(10, $this->currency->mathDecimals());
     }
 
     /** Format the value. */
@@ -171,6 +171,24 @@ final class Money implements JsonSerializable, Arrayable, Wireable
         ]));
     }
 
+    /**
+     * Create a Money instance from a formatted string.
+     *
+     * @param  string  $formatted The string formatted using the `formatted()` or `rawFormatted()` method.
+     * @param  Currency|string|null  $currency The currency to use when passing the overrides. If not provided, the currency of the formatted string is used.
+     * @param  array  ...$overrides The overrides used when formatting the money instance.
+     */
+    public static function fromFormatted(string $formatted, Currency|string $currency = null, mixed ...$overrides): self
+    {
+        $currency = isset($currency)
+            ? currency($currency)
+            : PriceFormatter::extractCurrency($formatted);
+
+        $decimal = PriceFormatter::resolve($formatted, $currency, variadic_array($overrides));
+
+        return static::fromDecimal($decimal, currency($currency));
+    }
+
     /** Get the string representation of the Money instance. */
     public function __toString(): string
     {
@@ -228,7 +246,7 @@ final class Money implements JsonSerializable, Arrayable, Wireable
 
         return $this
             ->divideBy($this->currency->rate())
-            ->divideBy(10 ** $mathDecimalDifference)
+            ->divideBy(pow(10, $mathDecimalDifference))
             ->value();
     }
 
@@ -240,7 +258,7 @@ final class Money implements JsonSerializable, Arrayable, Wireable
         $mathDecimalDifference = $newCurrency->mathDecimals() - currencies()->getDefault()->mathDecimals();
 
         return new static(
-            (int) round($this->valueInDefaultCurrency() * $newCurrency->rate() * 10 ** $mathDecimalDifference, 0),
+            (int) round($this->valueInDefaultCurrency() * $newCurrency->rate() * pow(10, $mathDecimalDifference), 0),
             $currency
         );
     }

src/PriceFormatter.php

@@ -4,6 +4,9 @@ declare(strict_types=1);
 
 namespace ArchTech\Money;
 
+use ArchTech\Money\Exceptions\CannotExtractCurrencyException;
+use Exception;
+
 class PriceFormatter
 {
     /** Format a decimal per the currency's specifications. */
@@ -22,4 +25,44 @@ class PriceFormatter
 
         return $currency->prefix() . $decimal . $currency->suffix();
     }
+
+    /** Extract the decimal from the formatted string as per the currency's specifications. */
+    public static function resolve(string $formatted, Currency $currency, array $overrides = []): float
+    {
+        $currency = Currency::fromArray(
+            array_merge(currency($currency)->toArray(), $overrides)
+        );
+
+        $formatted = ltrim($formatted, $currency->prefix());
+        $formatted = rtrim($formatted, $currency->suffix());
+
+        $removeNonDigits = preg_replace('/[^\d' . preg_quote($currency->decimalSeparator()) . ']/', '', $formatted);
+
+        if (! is_string($removeNonDigits)) {
+            throw new Exception('The formatted string could not be resolved to a valid number.');
+        }
+
+        return (float) str_replace($currency->decimalSeparator(), '.', $removeNonDigits);
+    }
+
+    /** Tries to extract the currency from the formatted string. */
+    public static function extractCurrency(string $formatted): Currency
+    {
+        $possibleCurrency = null;
+
+        foreach (currencies()->all() as $currency) {
+            if (
+                str_starts_with($formatted, $currency->prefix())
+                && str_ends_with($formatted, $currency->suffix())
+            ) {
+                if ($possibleCurrency) {
+                    throw new CannotExtractCurrencyException("Multiple currencies are using the same prefix and suffix as '$formatted'. Please specify the currency of the formatted string.");
+                }
+
+                $possibleCurrency = $currency;
+            }
+        }
+
+        return $possibleCurrency ?? throw new CannotExtractCurrencyException("None of the currencies are using the prefix and suffix that would match with the formatted string '$formatted'.");
+    }
 }

tests/Pest/MoneyTest.php

@@ -1,6 +1,7 @@
 <?php
 
 use ArchTech\Money\Currencies\USD;
+use ArchTech\Money\Exceptions\CannotExtractCurrencyException;
 use ArchTech\Money\Money;
 use ArchTech\Money\Tests\Currencies\CZK;
 use ArchTech\Money\Tests\Currencies\EUR;
@@ -147,6 +148,36 @@ test('money can be formatted without rounding', function () {
     )->toBe('10,34 Kč');
 });
 
+test('money can be created from a formatted string', function () {
+    $money = Money::fromFormatted('$10.40');
+    expect($money->value())->toBe(1040);
+});
+
+test('money can be created from a raw formatted string', function () {
+    currencies()->add([CZK::class]);
+
+    $money = Money::fromFormatted('1 234,56 Kč', CZK::class);
+    expect($money->value())->toBe(123456);
+});
+
+test('an exception is thrown if none of the currencies match the prefix and suffix', function () {
+    $money = money(1000);
+    $formatted = $money->formatted();
+
+    currencies()->remove(USD::class);
+
+    pest()->expectException(CannotExtractCurrencyException::class);
+    Money::fromFormatted($formatted);
+});
+
+test('an exception is thrown if multiple currencies are using the same prefix and suffix', function () {
+    currencies()->add(['code' => 'USD2', 'name' => 'USD2', 'prefix' => '$']);
+    $money = money(1000);
+
+    pest()->expectException(CannotExtractCurrencyException::class);
+    Money::fromFormatted($money->formatted());
+});
+
 test('converting money to a string returns the formatted string', function () {
     expect(
         (string) Money::fromDecimal(10.00, USD::class)