Restructure and reorganization

[techalchemy]

• Separation of concerns - actions are now separated from CLI interface
• Models are separated from 'internals'
• May want to think about what to do with internals to organize them
  a bit?
• Introduced models for most of the Object Oriented stuff
• Introduced options as a central aggregation of options and
  argument groups - this has 2 classes: Option and ArgumentGroup,
  each with the method add_to_parser for ease of use
• Command subclasses now simply take a list of options or argument
  groups and have a defined method to override called run(self, options) -- this way we can pass parameters to the corresponding actions
  rather than just blanketing the options in
• Closes Refactor procedural code in cli mains into operations  #21

Let me know if you have questions or want to change anything here. I tested a bunch of stuff and it seems to work, and (for me anyway) this is starting to make a lot of sense. Happy to work with you to make it clearer, but it's actually a lot easier for me to follow so if it's not too bad for you it'd be super helpful

Here is an example of cli.add:

class Command(BaseCommand):

    name = "add"
    description = "Add packages to project."
    arguments = [package_group]

    def run(self, options):
        if not options.editable_lines and not options.requirement_lines:
            self.parser.error("Must supply either a requirement or --editable")
        return add_packages(
            packages=options.packages,
            editables=options.editables,
            project=options.project,
            dev=options.dev
        )

and the corresponding actions.add

def add_packages(packages=[], editables=[], project=None, dev=False, sync=False, clean=False):
    from passa.models.lockers import PinReuseLocker
    from passa.operations.lock import lock
    ....

This way our core logic isn't tied exclusively to the CLI (and might be accessed by say, pipenv internals someday as a side-benefit)

Here is a new option (from cli.options):

dev_only = Option(
    "--dev", dest="only", action="store_const", const="dev",
    help="only try to modify [dev-packages]",
)

# and an argument group
package_group = ArgumentGroup("packages", options=[packages, editable, dev, no_sync])

[techalchemy]

FYI I am going to add some tests on top of this and merge it if you don't have any issues, since this makes it a lot easier to test as i mentioned somewhere else

[uranusjr]

Sure, I probably won’t have much time working on this for the next week, and if I find some I’ll work on creating a better mock PyPI server first.

[techalchemy]

No worries I don’t think I changed any functionality just moved stuff around. But if you want to release a patch release of master (or I can if you’re ok with it) I can bundle that as the.backup resolver and cut a release of pipenv

[uranusjr]

What does sync do? I am not sure Cleaner needs to be aware of Synchronizer.

[techalchemy]

I added it for the moment to see how the CLI feels with it (think of it like a --[no-]dry-run option... The actual reason related to a need to short-circuit the test environment's cleaning functionality, so don't take this as me thinking it should stay... just as a kind of 'does this seem like a good idea?' check

[uranusjr]

If it’s a dry run flag, I’d be more inclined to give it a different name, or (better IMO) to have a DryRunCleaner to do that.

[techalchemy]

seems like a good plan, haven't revisited it yet

[techalchemy]

hmmm looking at the code I'm not sure about this actually, I don't see a reason to reimplement the exact same functionality and print the same result just skip one line of activity... this isn't a java project...