add feature: detect mime type from file using finfo

src/Header/ContentType.php

@@ -61,7 +61,7 @@ public function getValue(): HeaderValue
     /**
      * @return ContentType
      */
-    public static function unknown()
+    public static function unknown(): ContentType
     {
         return new self('application/octet-stream', '');
     }

src/Header/HeaderValue.php

@@ -9,6 +9,14 @@
  */
 final class HeaderValue
 {
+    /**
+     *
+     */
+    private CONST PARSE_START = 1;
+    /**
+     *
+     */
+    private CONST PARSE_QUOTE = 2;
     /**
      * @var string
      */
@@ -129,4 +137,72 @@ public static function fromEncodedString(string $value): HeaderValue
         $headerValue->needsEncoding = false;
         return $headerValue;
     }
+
+    /**
+     * @param string $headerValueAsString
+     * @return HeaderValue
+     */
+    public static function fromString(string $headerValueAsString): HeaderValue
+    {
+        $values = [];
+
+        $headerValueAsString = trim($headerValueAsString);
+
+        $length = strlen($headerValueAsString) - 1;
+        $n = -1;
+        $state = self::PARSE_START;
+        $escapeNext = false;
+        $sequence = '';
+
+        while ($n < $length) {
+            $n++;
+
+            $char = $headerValueAsString[$n];
+
+            $sequence .= $char;
+
+            if ($char === '\\') {
+                $escapeNext = true;
+                continue;
+            }
+
+            if ($escapeNext) {
+                $escapeNext = false;
+                continue;
+            }
+
+            switch ($state) {
+                case self::PARSE_QUOTE:
+                    if ($char === '"') {
+                        $state = self::PARSE_START;
+                    }
+
+                    break;
+                default:
+                    if ($char === '"') {
+                        $state = self::PARSE_QUOTE;
+                    }
+
+                    if ($char === ';') {
+                        $values[] = trim(substr($sequence, 0, -1));
+                        $sequence = '';
+                        $state = self::PARSE_START;
+                    }
+                    break;
+            }
+        }
+
+        $values[] = trim($sequence);
+
+        $headerValue = new self($values[0]);
+
+        $parameters = [];
+        foreach (array_slice($values, 1) as $parameterString) {
+            $parameter = HeaderValueParameter::fromString($parameterString);
+            $parameters[$parameter->getName()] = $parameter;
+        }
+
+        $headerValue->parameters = $parameters;
+        return $headerValue;
+    }
 }

src/Header/HeaderValueParameter.php

@@ -66,4 +66,26 @@ public function __toString(): string
     {
         return sprintf('%s="%s"', $this->name, $this->value);
     }
+
+    /**
+     * @param string $parameterString
+     * @return HeaderValueParameter
+     */
+    public static function fromString(string $parameterString): HeaderValueParameter
+    {
+        $nameValue = explode('=', $parameterString);
+        if (count($nameValue) !== 2) {
+            throw new \InvalidArgumentException(
+                sprintf('Invalid parameter string value %s', $parameterString)
+            );
+        }
+
+        [$name, $value] = $nameValue;
+
+        if ($value[0] === '"' && $value[-1] === '"') {
+            $value = substr($value, 1, -1);
+        }
+
+        return new self($name, $value);
+    }
 }

src/Mime/FileAttachment.php

@@ -6,6 +6,7 @@
 use Genkgo\Mail\Header\ContentDisposition;
 use Genkgo\Mail\Header\ContentTransferEncoding;
 use Genkgo\Mail\Header\ContentType;
+use Genkgo\Mail\Header\HeaderValue;
 use Genkgo\Mail\HeaderInterface;
 use Genkgo\Mail\Stream\Base64EncodedStream;
 use Genkgo\Mail\StreamInterface;
@@ -41,6 +42,36 @@ public function __construct(string $filename, ContentType $contentType, string $
             ->withHeader(new ContentTransferEncoding('base64'));
     }
 
+    /**
+     * @param string $filename
+     * @param string $attachmentName
+     * @return FileAttachment
+     */
+    public static function fromUnknownFileType(string $filename, string $attachmentName = ''): FileAttachment
+    {
+        $fileInfo = new \finfo(FILEINFO_MIME);
+        $mime = $fileInfo->file($filename);
+
+        $headerValue = HeaderValue::fromString($mime);
+
+        try {
+            $charset = $headerValue->getParameter('charset')->getValue();
+            if ($charset === 'binary') {
+                $contentType = new ContentType($headerValue->getRaw());
+            } else {
+                $contentType = new ContentType($headerValue->getRaw(), $charset);
+            }
+        } catch (\UnexpectedValueException $e) {
+            $contentType = new ContentType($headerValue->getRaw());
+        }
+
+        return new self(
+            $filename,
+            $contentType,
+            $attachmentName
+        );
+    }
+
     /**
      * @return iterable
      */

test/Unit/Header/HeaderValueParameterTest.php

@@ -0,0 +1,45 @@
+<?php
+declare(strict_types=1);
+
+namespace Genkgo\TestMail\Unit\Header;
+
+use Genkgo\Mail\Header\HeaderValueParameter;
+use Genkgo\TestMail\AbstractTestCase;
+
+final class HeaderValueParameterTest extends AbstractTestCase
+{
+
+    /**
+     * @test
+     */
+    public function it_can_parse_a_string()
+    {
+        $parameter = HeaderValueParameter::fromString('charset="utf-8"');
+
+        $this->assertEquals((string)$parameter, 'charset="utf-8"');
+        $this->assertEquals($parameter->getName(), 'charset');
+        $this->assertEquals($parameter->getValue(), 'utf-8');
+    }
+
+    /**
+     * @test
+     */
+    public function it_can_parse_an_unquoted_string()
+    {
+        $parameter = HeaderValueParameter::fromString('charset=utf-8');
+
+        $this->assertEquals((string)$parameter, 'charset="utf-8"');
+        $this->assertEquals($parameter->getName(), 'charset');
+        $this->assertEquals($parameter->getValue(), 'utf-8');
+    }
+
+    /**
+     * @test
+     */
+    public function it_does_not_parse_invalid_values()
+    {
+        $this->expectException(\InvalidArgumentException::class);
+        HeaderValueParameter::fromString('charset,utf-8');
+    }
+
+}

test/Unit/Header/HeaderValueTest.php

@@ -74,4 +74,27 @@ public function it_overwrites_parameters()
 
         $this->assertEquals('value; name1="value2"', (string)$header);
     }
+
+    /**
+     * @test
+     */
+    public function it_can_parse_a_string()
+    {
+        $header = HeaderValue::fromString('application/pdf; charset="utf-8"');
+
+        $this->assertEquals('application/pdf; charset="utf-8"', (string)$header);
+        $this->assertEquals('charset="utf-8"', (string)$header->getParameter('charset'));
+    }
+
+    /**
+     * @test
+     */
+    public function it_can_parse_a_string_with_more_than_one_parameter()
+    {
+        $header = HeaderValue::fromString('application/pdf; charset="utf-8"; foo="bar"');
+
+        $this->assertEquals('application/pdf; charset="utf-8"; foo="bar"', (string)$header);
+        $this->assertEquals('charset="utf-8"', (string)$header->getParameter('charset'));
+        $this->assertEquals('foo="bar"', (string)$header->getParameter('foo'));
+    }
 }

test/Unit/Mime/FileAttachmentTest.php

@@ -110,4 +110,19 @@ public function it_encodes_body_with_base64()
 
         $this->assertInstanceOf(Base64EncodedStream::class, $attachment->getBody());
     }
+
+    /**
+     * @test
+     */
+    public function it_is_able_to_detect_mime_type()
+    {
+        $attachment = FileAttachment::fromUnknownFileType(
+            __DIR__ .'/../../Stub/minimal.pdf'
+        );
+
+        $this->assertEquals(
+            'application/pdf; charset="utf-8"',
+            (string) $attachment->getHeader('Content-Type')->getValue()
+        );
+    }
 }