port MsgBlockParser from TypeScript to Kotlinpgp message block parser

[tomholub]

As a part of #1051 we'll need to port the following https://github.com/FlowCrypt/flowcrypt-browser/blob/master/extension/js/common/core/msg-block-parser.ts but only method detectBlocks with its private counterpart detectBlockNext. I recommend to port it line-by-line so that we can easily reason about it - the original parser is well battle tested.

The Android codebase already has a class similar to TypeScript's MsgBlock here https://github.com/FlowCrypt/flowcrypt-browser/blob/master/extension/js/common/core/msg-block.ts - @DenBond7 can you please point us to where is the Android/Kotlin equivalent defined?

For the implementation I'd recommend to do it in this order:

1. open the typescript codebase in vscode to better understand it
2. from https://github.com/FlowCrypt/flowcrypt-browser/blob/master/test/source/tests/unit-node.ts copy first 3 tests that start with [unit][MsgBlockParser.detectBlocks] into kotlin
3. copy the algorithm and translate into Kotlin line by line
4. most test cases are unfortunately, in browser-extension, run as integration tests. I recommend to find a way to run all tests and export the results into a file, to work as data for unit tests in Kotlin. I'm not entirely sure what the right way to do this is, since the test runner is in NodeJS but the tested code itself runs in puppeteer. When unsure, ask @rrrooommmaaa for help
5. once exported data for unit tests, write appropriate Kotlin unit tests and fix implementation if necessary

[tomholub]

This will be for @IvanPizhenko whom I've just invited to the repo https://github.com/FlowCrypt/flowcrypt-android/invitations

[DenBond7]

can you please point us to where is the Android/Kotlin equivalent defined?

Please look at MsgBlockDeserializer. There you will find the info which blocks we currently support on Android

And in this place lie Kotlin classes for blocks

[IvanPizhenko]

I have a question - where to place method detectBlocks()? i.e. in what class and in what package?

[IvanPizhenko]

Meanwhile will put in the new class MsgBlockParser in the place mentioned above by Den.

[tomholub]

I also don't know. Den will clarify tomorrow.

[DenBond7]

I have a question - where to place method detectBlocks()? i.e. in what class and in what package?

@IvanPizhenko Please use com.flowcrypt.email.core.msg as a package and store MsgBlockParser there. I think later we will move all blocks to com.flowcrypt.email.core.msg.blocks

[IvanPizhenko]

I think I've ported the code, now need to get some unit tests.
@rrrooommmaaa Can you plase point me where are unit tests for the block parser?

[tomholub]

from https://github.com/FlowCrypt/flowcrypt-browser/blob/master/test/source/tests/unit-node.ts copy first 3 tests that start with [unit][MsgBlockParser.detectBlocks] into kotlin

Can start here

[IvanPizhenko]

@tomholub So I have got those 3 tests passing - what's next? Are there any other unit test that should be ported or I can submit PR in this state?