Use php-intl to format currencies

Currently the php function `number_format` is used to format currencies.
This is problematic as we have to figure out different things for
different currencies ourselves. These formats are determined based on
the libc's locale functions.

The issue arises where an OS doesn't have the proper locales installed,
or, in some cases, it's not supported (see below on multiple issues).

This addresses this issue by using the php-intl extensions to format the
numbers based on the locale. The extension is already a requirement in
`composer.json`. The solution does not rely on `LC_MONETARY` from the
underlying libc (which in Alpine Linux's case, which uses musl, is not
supported as of yet).

List of issues that are related and would potentially be fixed using
this PR:

- #2298
- #2946
- #3070
- #3306
- #3519

app/Support/Amount.php

@@ -28,6 +28,7 @@ use FireflyIII\User;
 use Illuminate\Contracts\Encryption\DecryptException;
 use Illuminate\Support\Collection;
 use Log;
+use NumberFormatter;
 
 /**
  * Class Amount.
@@ -37,80 +38,6 @@ use Log;
 class Amount
 {
 
-    /**
-     * bool $sepBySpace is $localeconv['n_sep_by_space']
-     * int $signPosn = $localeconv['n_sign_posn']
-     * string $sign = $localeconv['negative_sign']
-     * bool $csPrecedes = $localeconv['n_cs_precedes'].
-     *
-     * @param bool   $sepBySpace
-     * @param int    $signPosn
-     * @param string $sign
-     * @param bool   $csPrecedes
-     *
-     * @return string
-     *
-     */
-    public static function getAmountJsConfig(bool $sepBySpace, int $signPosn, string $sign, bool $csPrecedes): string
-    {
-        // negative first:
-        $space = ' ';
-
-        // require space between symbol and amount?
-        if (false === $sepBySpace) {
-            $space = ''; // no
-        }
-
-        // there are five possible positions for the "+" or "-" sign (if it is even used)
-        // pos_a and pos_e could be the ( and ) symbol.
-        $posA = ''; // before everything
-        $posB = ''; // before currency symbol
-        $posC = ''; // after currency symbol
-        $posD = ''; // before amount
-        $posE = ''; // after everything
-
-        // format would be (currency before amount)
-        // AB%sC_D%vE
-        // or:
-        // AD%v_B%sCE (amount before currency)
-        // the _ is the optional space
-
-        // switch on how to display amount:
-        switch ($signPosn) {
-            default:
-            case 0:
-                // ( and ) around the whole thing
-                $posA = '(';
-                $posE = ')';
-                break;
-            case 1:
-                // The sign string precedes the quantity and currency_symbol
-                $posA = $sign;
-                break;
-            case 2:
-                // The sign string succeeds the quantity and currency_symbol
-                $posE = $sign;
-                break;
-            case 3:
-                // The sign string immediately precedes the currency_symbol
-                $posB = $sign;
-                break;
-            case 4:
-                // The sign string immediately succeeds the currency_symbol
-                $posC = $sign;
-        }
-
-        // default is amount before currency
-        $format = $posA . $posD . '%v' . $space . $posB . '%s' . $posC . $posE;
-
-        if ($csPrecedes) {
-            // alternative is currency before amount
-            $format = $posA . $posB . '%s' . $posC . $space . $posD . '%v' . $posE;
-        }
-
-        return $format;
-    }
-
     /**
      * This method will properly format the given number, in color or "black and white",
      * as a currency, given two things: the currency required and the current locale.
@@ -142,13 +69,16 @@ class Amount
      */
     public function formatFlat(string $symbol, int $decimalPlaces, string $amount, bool $coloured = null): string
     {
+        $locale = app('steam')->getLocale();
+
         $coloured  = $coloured ?? true;
-        $info      = $this->getLocaleInfo();
-        $formatted = number_format((float) $amount, $decimalPlaces, $info['mon_decimal_point'], $info['mon_thousands_sep']);
-        $precedes  = $amount < 0 ? $info['n_cs_precedes'] : $info['p_cs_precedes'];
-        $separated = $amount < 0 ? $info['n_sep_by_space'] : $info['p_sep_by_space'];
-        $space     = true === $separated ? ' ' : '';
-        $result    = false === $precedes ? $formatted . $space . $symbol : $symbol . $space . $formatted;
+        $float     = round($amount, 12);
+
+        $fmt = new NumberFormatter( $locale, NumberFormatter::CURRENCY );
+        $fmt->setSymbol(NumberFormatter::CURRENCY_SYMBOL, $symbol);
+        $fmt->setAttribute(NumberFormatter::MIN_FRACTION_DIGITS, $decimalPlaces);
+        $fmt->setAttribute(NumberFormatter::MAX_FRACTION_DIGITS, $decimalPlaces);
+        $result = $fmt->format($float);
 
         if (true === $coloured) {
             if ($amount > 0) {
@@ -300,58 +230,31 @@ class Amount
     }
 
     /**
-     * This method returns the correct format rules required by accounting.js,
-     * the library used to format amounts in charts.
-     *
-     * @param array $config
-     *
      * @return array
      */
-    public function getJsConfig(array $config): array
+    public function getAccountingLocaleInfo(): array
     {
-        $negative = self::getAmountJsConfig($config['n_sep_by_space'], $config['n_sign_posn'], $config['negative_sign'], $config['n_cs_precedes']);
-        $positive = self::getAmountJsConfig($config['p_sep_by_space'], $config['p_sign_posn'], $config['positive_sign'], $config['p_cs_precedes']);
+        $locale = app('steam')->getLocale();
+
+        $fmt = new NumberFormatter( $locale, NumberFormatter::CURRENCY );
+
+        $positivePrefixed = $fmt->getAttribute(NumberFormatter::POSITIVE_PREFIX) !== '';
+        $negativePrefixed = $fmt->getAttribute(NumberFormatter::NEGATIVE_PREFIX) !== '';
+
+        $positive = ($positivePrefixed) ? '%s %v' : '%v %s';
+        $negative = ($negativePrefixed) ? '%s %v' : '%v %s';
 
         return [
-            'pos'  => $positive,
-            'neg'  => $negative,
-            'zero' => $positive,
+            'mon_decimal_point' => $fmt->getSymbol(NumberFormatter::MONETARY_SEPARATOR_SYMBOL),
+            'mon_thousands_sep' => $fmt->getSymbol(NumberFormatter::MONETARY_GROUPING_SEPARATOR_SYMBOL),
+            'format' => [
+                'pos'  => $positive,
+                'neg'  => $negative,
+                'zero' => $positive,
+            ]
         ];
     }
 
-    /**
-     * @return array
-     */
-    public function getLocaleInfo(): array
-    {
-        // get config from preference, not from translation:
-        $locale = app('steam')->getLocale();
-        $array  = app('steam')->getLocaleArray($locale);
-
-        setlocale(LC_MONETARY, $array);
-        $info = localeconv();
-        // correct variables
-        $info['n_cs_precedes'] = $this->getLocaleField($info, 'n_cs_precedes');
-        $info['p_cs_precedes'] = $this->getLocaleField($info, 'p_cs_precedes');
-
-        $info['n_sep_by_space'] = $this->getLocaleField($info, 'n_sep_by_space');
-        $info['p_sep_by_space'] = $this->getLocaleField($info, 'p_sep_by_space');
-
-        return $info;
-    }
-
-    /**
-     * @param array  $info
-     * @param string $field
-     *
-     * @return bool
-     */
-    private function getLocaleField(array $info, string $field): bool
-    {
-        return (is_bool($info[$field]) && true === $info[$field])
-               || (is_int($info[$field]) && 1 === $info[$field]);
-    }
-
     /**
      * @param string $value
      *