This PR introduces an EML parser to go-mail. It allows to read generic EML data from a file, a string or a reader into a go-mail Msg struct. It supports all types of message parts and encodings. It should be able to recognize Mulitpart messages as well as attachments and embeds (inline attachments).
This PR closes#145
Added conditional statements to handle potential failures when writing the EML string to the temporary files during testing. These updates ensure test failures due to write errors are accurately reflected in test results. Also, a minor fix is implemented on file permission in the os.WriteFile function.
The README has been updated to show that go-mail now supports outputting a message as an EML file and parsing an EML file into a go-mail message. This addition enhances the flexibility and control over the email content and format.
The change introduces a new unit test, TestFile_WithContentID, in file_test.go. This test aims to verify the correct function of the WithFileContentID option by using differing scenarios, with assertions for error control and validation of expected content.
In the eml.go and file.go files, the function WithContentID has been renamed to WithFileContentID. This aligns more accurately with the function purpose, which is to set the content ID for a File object.
This commit introduces tests for different email scenarios including emails with no boundaries, emails with attachments, emails with embedded items, and multipart mixed emails. The tests ensure that the code correctly returns all expected parts of the email (e.g., embeds, attachments, parts) and that it correctly processes the email subject.
The debug print statement that outputs the content type of the email has been removed from eml.go. This change improves code cleanliness and avoids unnecessary console output in production.
The comment in the eml.go file was extended to include the possibility of 'Multipart/alternative' parts. Previously, it only mentioned 'Multipart/related' parts. The actual code functionality remains unchanged, this is purely a clarification in the documentation.
The EML parser now includes logic to manage 'multipart/alternative' content types. This adjustment is made within the section handling 'multipart/related' parts, allowing for better handling and parsing of varying content types.
The updated code adds base64 encoding support to email attachments and inline content in eml.go. It does this by introducing a new dataReader which uses a base64 decoder if the content transfer encoding is base64. With this update, attachments with base64 content will be correctly decoded when processed.
The newly added function, WithContentID, allows for setting the Content-ID header for the File. This provides enhanced handling and differentiation of files.
The commit modifies the parseMultiPartHeader function to handle optional fields accurately. The delimiter was changed from "; " to ";" and whitespace is being trimmed from the start of optional fields to ensure correct splitting and mapping.
The error message previously referenced a constant 'HeaderTo' which might not always be the header being parsed. The commit replaces this with 'addrHeader', significantly improving the accuracy of error messages.
Refactored the way EML files are tested, the errors are now handled more efficiently. Temporary directory and file creation, as well as file writing, have been moved to a helper function named 'stringToTempFile'. Moreover, additional test cases were added to ensure proper parsing failure for various types of email-related errors.
The previous separate parsing of EML headers and body parts has been refactored into a single function, parseEML. This change simplifies the operations in the readEML and makes the code cleaner by reducing repetition.
New failing tests have been added to 'eml_test.go' to account for a variety of error situations, such as broken FROM, TO, headers, bodies, and unknown or unsupported content types. Improving the robustness of test coverage helps identify potential issues and ensure the resilience and correctness of the code.
The update adds a case to the switch clause in eml.go for properly handling unknown content types. An error will now be returned when the media type of the body to be parsed is not recognized, increasing the robustness of the system.
The new test ensures that the EMLToMsgFromString function properly handles an EML that contains embedded content. The expected subject content and number of embedded objects are checked to confirm correct parsing.
This update expands the EML parser to support multipart/related content types. It also includes relevant error handling and creates a specific routine for parsing multipart/related parts separately. Furthermore, adjustments were made to avoid processing headers unnecessarily when TypeMultipartMixed is used. The diff also shows some refactoring for clearer error messages and cleaner code.
The content print statement in eml.go was removed to optimize code readability and performance. In addition, several assertions in the test cases of eml_test.go were corrected for string formatting errors and a new test case was added for handling emails with attachments. These changes aim to enhance the robustness of tests for email encoding and decoding operations.
The EML parsing has been refactored to separate the handling of attachments and embeds into a new helper function. This improves the organization of the code, makes it easier to understand and helps to better manage error handling and resource closing.
The code is refactored to improve multipart parsing in EML. The `parseEMLMultipartAlternative` function is updated to `parseEMLMultipart` for more general utilization. This involves iterating through the parts of a multipart message until content disposition is found and appended. A new function `parseMultiPartHeader` is introduced to parse multipart header and handle charset more sensibly.
The commit includes extraction of blocks of code related to EML message encoding and content-type parsing into their own separate functions. By doing so, it improves code readability and maintainability.
Introduced a new test, `TestEMLToMsgFromFile`, to validate the functions responsible for EML message parsing. This complements the existing `EMLToMsgFromString` test, holding them accountable for subject and encoding accuracy. Also, a temporary directory is now created for testing File-related operations in isolation.
Variable names in eml.go have been refactored for better readability and understanding. Shortened abbreviations have been expanded into meaningful names, and complex object names have been made simpler, making it easier to understand their role within the codebase. Cooperative variable names will improve maintainability and ease future development. This is a follow up to #179 which didn't consider this branch.
