[#31] Refactor and simplify CLI

[chshersh]

Resolves #31

I implemented the changes described in #31 🎉

It was a massive refactoring because I realised that changing CLI simply to make the interactive behaviour the default one is not that simple. As a result, the entire DrCabal.Interactive module was removed and I incorporated its changes to DrCabal.Watch (sorry @Bodigrim).

Now:

• The interactive mode is the default mode
• The UI is simplified to the single command
• There's still an ability to read from files and output to files
  • TODO: This needs more testing, I didn't have the time to test it yet

Now, to run the profiling, you only need to do the following command:

cabal --store-dir=$(mktemp -d) --dependencies-only build all | dr-cabal profile

I haven't updated the documentation yet and I will do it as a part of #30.

The only problem so far is when the profiling output is longer than the screen height, I can't scroll back and the output seems to be mangled in a horrible way:

@Bodigrim Did you observe the same behaviour when you implemented the interactive command? Maybe I changed something wrongly during this refactoring 🤔

[Bodigrim]

The only problem so far is when the profiling output is longer than the screen height, I can't scroll back and the output seems to be mangled in a horrible way

Yeah, I've seen the same effect, when scrolling upwards an output larger than viewpoint. AFAIU this is a fundamental limitation of the primary screen buffer, unless you switch to an alternate screen buffer as full-screen terminal applications do (htop, etc.).

[chshersh]

@Bodigrim Do you know if there's an easy way to use an alternative screen buffer (like writing a single line of code)?

I find the current behavior undesirable so I'm thinking about possible solutions, e.g. printing only the first "terminal window height" lines during the interactive mode.

[chshersh]

Okay, here is a simple program that starts an alternate terminal screen (inspired by this) and and returns back after it. I can try to use it in dr-cabal to see how it goes:

I haven't found relevant functions in ansi-terminal which is too bad 😞

#!/usr/bin/env cabal
{- cabal:
build-depends:
  , base ^>= 4.16
-}

{-# LANGUAGE NumericUnderscores #-}
{-# LANGUAGE ScopedTypeVariables #-}

module Main where

import Control.Concurrent
import Data.Foldable

main :: IO ()
main = do
    putStrLn "\ESC[?1049h\ESC[H"

    for_ [1 .. 5] $ \(i :: Int) -> do
        putStrLn $ "Going back in: " <> show i
        threadDelay 1_000_000

    putStrLn "\ESC[?1049l"

[chshersh]

Anyway, here's a relevant issue in ansi-terminal:

• Support alternative terminal screens UnkindPartition/ansi-terminal#147

[chshersh]

By default, dr-cabal now outputs the profiling chart in the alternate screen buffer (and then duplicates the final result after switching to the normal buffer).

It handles exceptions and SIGINT correctly if interrupted during interactive output so it would switch back again correctly. Nothing is printed in the terminal on Ctrl+C but this could be one of the future improvements 🙂

There's so much I can do in a limited time... But at least I'm satisfied enough with the current behaviour, although, it took a while to achieve the result 😮‍💨

[Bodigrim]

Looks great!