# `Lather.Mtom.Mime`
[🔗](https://github.com/awksedgreep/lather/blob/v1.0.49/lib/lather/mtom/mime.ex#L1)

MIME utilities for MTOM multipart/related message handling.

This module provides functions for building and parsing multipart/related
MIME messages used in MTOM (Message Transmission Optimization Mechanism).

MTOM messages use the multipart/related content type with the following structure:

    Content-Type: multipart/related;
                  boundary="uuid:12345-abcde";
                  type="application/xop+xml";
                  start="<rootpart@lather.soap>"

    --uuid:12345-abcde
    Content-Type: application/xop+xml; charset=UTF-8; type="text/xml"
    Content-Transfer-Encoding: 8bit
    Content-ID: <rootpart@lather.soap>

    <?xml version="1.0"?>
    <soap:Envelope>
      <!-- SOAP envelope with XOP includes -->
    </soap:Envelope>

    --uuid:12345-abcde
    Content-Type: application/pdf
    Content-Transfer-Encoding: binary
    Content-ID: <attachment123@lather.soap>

    %PDF-1.4 [binary data]...
    --uuid:12345-abcde--

# `build_content_type_header`

```elixir
@spec build_content_type_header(String.t(), String.t(), String.t()) :: String.t()
```

Builds a Content-Type header for multipart/related messages.

## Parameters

  * `boundary` - Multipart boundary
  * `type` - Root part type
  * `start` - Root part Content-ID

## Returns

  * Complete Content-Type header value

## Examples

    header = Mime.build_content_type_header("uuid:123", "application/xop+xml", "root@soap")

# `build_multipart_message`

```elixir
@spec build_multipart_message(binary(), [Lather.Mtom.Attachment.t()], keyword()) ::
  {String.t(), binary()}
```

Builds a complete multipart/related MIME message with SOAP envelope and attachments.

## Parameters

  * `soap_envelope` - The SOAP envelope XML as binary
  * `attachments` - List of Attachment structs
  * `options` - Additional options

## Options

  * `:boundary` - Custom boundary (auto-generated if not provided)
  * `:soap_content_type` - SOAP part content type (default: "application/xop+xml")
  * `:soap_charset` - SOAP part charset (default: "UTF-8")

## Returns

  * `{content_type_header, multipart_body}` - Complete MIME message

## Examples

    {content_type, body} = Mime.build_multipart_message(soap_xml, attachments)

# `extract_boundary`

```elixir
@spec extract_boundary(String.t()) :: {:ok, String.t()} | {:error, atom()}
```

Extracts the boundary parameter from a Content-Type header.

## Parameters

  * `content_type` - Content-Type header value

## Returns

  * `{:ok, boundary}` - Successfully extracted boundary
  * `{:error, reason}` - Extraction failed

## Examples

    {:ok, boundary} = Mime.extract_boundary("multipart/related; boundary="uuid:123"")

# `generate_boundary`

```elixir
@spec generate_boundary() :: String.t()
```

Generates a unique boundary string for multipart messages.

## Returns

  * Boundary string suitable for multipart MIME messages

## Examples

    boundary = Mime.generate_boundary()
    # "uuid:a1b2c3d4-e5f6-7890-abcd-ef1234567890"

# `parse_headers`

```elixir
@spec parse_headers(binary()) :: map()
```

Parses MIME headers from a header section.

## Parameters

  * `header_section` - Raw header text

## Returns

  * Map of parsed headers with lowercase keys

## Examples

    headers = Mime.parse_headers("Content-Type: application/pdf\r\nContent-ID: <att1>")
    # %{"content-type" => "application/pdf", "content-id" => "<att1>"}

# `parse_multipart_message`

```elixir
@spec parse_multipart_message(String.t(), binary(), keyword()) ::
  {:ok, {binary(), [map()]}} | {:error, term()}
```

Parses a multipart/related MIME message.

## Parameters

  * `content_type` - The Content-Type header value
  * `body` - The multipart message body
  * `options` - Parsing options

## Returns

  * `{:ok, {soap_part, attachments}}` - Successfully parsed message
  * `{:error, reason}` - Parsing error

## Examples

    {:ok, {soap_xml, attachments}} = Mime.parse_multipart_message(content_type, body)

# `validate_content_type`

```elixir
@spec validate_content_type(String.t()) :: :ok | {:error, atom()}
```

Validates a multipart/related Content-Type header.

## Parameters

  * `content_type` - Content-Type header to validate

## Returns

  * `:ok` if valid, `{:error, reason}` if invalid

---

*Consult [api-reference.md](api-reference.md) for complete listing*