WIP: Add quiet mode to pre-commit run

[allburov]

Add --quiet flag ot pre-commit run to show only failing hook's messages.

Fix #823

TODO:

• Add --quiet flag to pre-commit run
• Introduce env variable PRE_COMMIT_QUIET=0|1|false|true which allow users to enable quiet mode by default in their PC
• Add option --output-mode=[normal|quiet] to pre-commit install command
• Add docs about flag and option to https://github.com/pre-commit/pre-commit.github.io

[allburov]

@asottile what about this to fix #823? Could you review this solution, please.

[asottile]

first off, thanks for working on this

I don't think I can accept this in its current state, there's a ton of complexity added in this patch (for a feature I'll never really use) that I'm not comfortable with. Also the use of inheritance when a function would do seems not a good idea

let me know if you'd like a more in depth review but I think this feature might just be too complex to implement (and especially in one go)

[allburov]

@asottile
I understand your opinion, very few repositories have more than 10 hooks (I have looked to open source repositories). But a big project (without shared code base) may have a lot of hooks. However it's really less than 1% of repositories who use pre-commit.

I tried write this with if-statements, but it looked hard.
I tried rewrite with "pass args.quiet" to functions (like args.color is passed) - it did not seem pythonic and easy to read or modify.
I looked at logging or ansible.display solutions also, but it also will have if statement to print the first status message with number of hooks.

So my decision is just inject new output to run hook function. If you will want to write new string to console in the function you just will use write_line or write and don't wary about quiet mode.

Lets going to simplify the solution (if we will can without increase complexity)!

[blueyed]

@allburov
Maybe wrapping the whole output / run is more feasible in the long run? 77aab5e

[peterjc]

I tried the other extreme in #1560, no output wrapping at all - just suppressing "skipped" message output in the first place. This seemed like the low hanging fruit, and made me wonder about having that off by default - thus #1561 which only shows the "skipped" messages in verbose mode.