first rendition of contributing docs & remove format

Signed-off-by: ZeldaZach <zahalpern+github@gmail.com>

CONTRIBUTING.md

@@ -0,0 +1,46 @@
+# Contributing to MTGJSON
+
+First off, thanks for taking the time to read this document! It means something to us that you're potentially interested in helping improve our project.
+
+Our goal for MTGJSON was and is to provide free and easily accessible Magic: the Gathering data for those who want and/or need it.
+
+If you're not a software developer, but want to help the project in some way, we are always looking for individuals to audit the content we provide. We also accept financial contributions to the project via [PayPal](https://www.paypal.me/zachhalpern) and [Patreon](https://patreon.com/mtgjson).
+
+## Environment Setup
+
+Here at MTGJSON, we recommend all of our developers check out [PyCharm](https://jetbrains.com/pycharm/). While any IDE or notepad can be used, we found that the JetBrains environment is intuitive and easy to understand.
+
+In addition to PyCharm, you'll need to install Python 3. We develop actively on the latest release of Python, but aim for compatibility with Python 3.6.
+
+- Mac: `brew install python3`
+- Linux: `sudo apt-get install python3.7`
+- Windows: [Download Python 3](https://www.python.org/downloads/)
+
+
+## Project Hierarchy
+The codebase is split up into different files based on functionality. While not perfect, we aim to segregate components based on their usages and dependencies.
+
+- `provider/`  is where we put code for each 3rd party resource we need to contact in order to collate our data. Each source should be given its own folder and should not be dependent on any other provider.
+- `resources/` is where we put MTGJSON corrections, fixes, and hard caches. These are data points we want to include, but can't grab from an external entity easily or without causing a circular loop.
+- `__main__.py` is where we define our globals for the project. TODO is to re-write them into their own class.
+- `compile_mtg.py` is the main functionality of the project, where we handle turning data blobs into MTGJSON cards and sets.
+- `compressor.py` is where we compress completed outputs for release.
+- `outputter.py` is where all I/O operations should take place. All write to disk calls should be done from here.
+- `util.py` are common utilities that may be used across the codebase.
+
+## Code Style & Testing
+
+We follow the [black](https://pypi.org/project/black/) style guides, a stricter version of [PEP-8](https://www.python.org/dev/peps/pep-0008/) styling.
+
+To reformat your code and ensure compatibility with our system, simply run the Tox file found in the repo before you open up a pull request.
+- Before running Tox, you'll need to install the requirements
+    - `python3 install -r requirements_test.txt`
+- In PyCharm, simply right click on `tox.ini` and click "Run Tox"
+
+You will need to pass all Tox requirements, including the unit tests, for your pull request to be approved.
+
+## Communication Channels
+
+We communicate almost exclusively through [Discord](https://mtgjson.com/discord). Feel free to join us, whether you're a developer or not. We love chatting with the community!
+
+MTGJSON staff can be identified with a blue name, and our staff listing is found on the [website](https://mtgjson.com/).

mtgjson4/outputter.py

@@ -8,7 +8,6 @@
 
 import mtgjson4
 from mtgjson4 import SUPPORTED_FORMAT_OUTPUTS, util
-from mtgjson4.format import build_format_map
 from mtgjson4.mtgjson_card import MTGJSONCard
 from mtgjson4.provider import magic_precons, scryfall, wizards
 
@@ -397,7 +396,7 @@ def create_set_centric_outputs(sets: Dict[str, Any]) -> None:
     :param sets: Dictionary mapping name -> card data. Should be AllSets.
     """
     # Compute format map from all_sets
-    format_map = build_format_map(sets)
+    format_map = util.build_format_map(sets)
     LOGGER.info(f"Format Map: {format_map}")
 
     # Standard.json

mtgjson4/util.py

@@ -8,7 +8,7 @@
 import re
 import shutil
 import tempfile
-from typing import Any, List, Optional
+from typing import Any, Dict, List, Optional, Set
 import unicodedata
 
 import requests
@@ -27,6 +27,14 @@
 
 STANDARD_API_URL: str = "https://whatsinstandard.com/api/v5/sets.json"
 
+NORMAL_SETS: Set[str] = {
+    "expansion",
+    "core",
+    "draft_innovation",
+    "commander",
+    "masters",
+}
+
 
 def retryable_session(session: requests.Session, retries: int = 8) -> requests.Session:
     """
@@ -229,3 +237,34 @@ def set_gist_json_file(
 
     LOGGER.info("Removing local CH database")
     shutil.rmtree(temp_working_dir)
+
+
+def build_format_map(
+    all_sets: Dict[str, Any], regular: bool = True
+) -> Dict[str, List[str]]:
+    """
+    For each set in the specified JSON file, determine its legal sets and return a dictionary mapping set code to
+    a list of legal formats.
+    :param all_sets: AllSets content
+    :param regular: If this is True, then unusual sets will be excluded.
+    :return: Dictionary of the form { format: [codes] }
+    """
+    formats: Dict[str, List[Any]] = {
+        fmt: [] for fmt in mtgjson4.SUPPORTED_FORMAT_OUTPUTS
+    }
+
+    for code, data in all_sets.items():
+        if regular and data["type"] not in NORMAL_SETS:
+            continue
+
+        possible_formats = mtgjson4.SUPPORTED_FORMAT_OUTPUTS
+
+        for card in data.get("cards"):
+            # The legalities dictionary only has keys for formats where the card is legal, banned or restricted.
+            card_formats = set(card.get("legalities").keys())
+            possible_formats = possible_formats.intersection(card_formats)
+
+        for fmt in possible_formats:
+            formats[fmt].append(code)
+
+    return formats

tests/mtgjson4/test_format.py

@@ -1,6 +1,6 @@
 import pytest
 
-from mtgjson4.format import build_format_map
+from mtgjson4.util import build_format_map
 
 
 NULL_OUTPUT = {"standard": [], "modern": [], "legacy": [], "vintage": [], "pauper": []}