[CLI]: Table not rendered properly

[ShauryaAg]

Bug Report

exp show: table not rendered properly

Description

When dvc exp show is run, the table is not rendered properly

Reproduce

1. Run some experiments in dvc
2. Run dvc exp show

Expected

Table should be rendered properly like:

Environment information

OS: WIndows 10 Home
Python version: 3.7.8

Output of dvc doctor:

$ dvc doctor

DVC version: 2.5.4 (pip)
---------------------------------
Platform: Python 3.7.8 on Windows-10-10.0.19041-SP0
Supports:
        http (requests = 2.26.0),
        https (requests = 2.26.0)
Cache types: hardlink
Cache directory: NTFS on D:\
Caches: local
Remotes: None
Workspace directory: NTFS on D:\
Repo: dvc, git

Additional Information (if any):
The table is rendered properly from Linux environment (using WSL on windows), but not in Windows env.

[pmrowla]

@ShauryaAg what font are you using in cmd prompt or powershell?

[skshetry]

The problem is with the less pager and happens across cmd prompt, powershell and git-bash, using --no-pager should work fine. I am trying to see if the newest version of less works.

[skshetry]

Okay, I was able to figure out what the issue is.

We use tempfilepager which saves the file to a temporary file as follows (here):

with open(filename, 'w', errors='backslashreplace') as file:
    file.write(text)

As the rich's table is expected to be in utf-8, and the default encoding might be different on Windows, we need to dump the file in utf-8 and dump it in the same encoding.

For me, setting PYTHONUTF8=1, chcp 65001 and LESSCHARSET="utf-8" worked. I am still not sure what the fix should look like, as it still involves user setting their appropriate encoding, even if we page the output in utf-8 encoding.

The easiest solution would be to just use ascii2 border in the rich table.

[ShauryaAg]

Upon some testing, I have figured out one solution to the problem.
On line 94:

dvc/dvc/ui/table.py

Lines 93 to 98 in fb96b13

	border_style = {
	True: box.HEAVY_HEAD, # is a default in rich,
	False: None,
	"simple": box.SIMPLE,
	"minimal": box.MINIMAL,
	}

This can be changed to something like

import platform
WINDOWS = platform.system() == "Windows"

....
border_style = { 
     True: box.ASCII_DOUBLE_HEAD if WINDOWS else box.HEAVY_HEAD,
     False: None, 
     "simple": box.SIMPLE, 
     "minimal": box.MINIMAL, 
} 
....

This way we can print a table like the following for Windows while maintaining the current type for Linux

+---+---+---+
| A | B | C |
+===+===+===+
| a | b | c |
| 1 | 2 | 3 |
| 4 | 5 | 6 |
+---+---+---+

Please let me know if the solution seems ok to you. I'd like to make a PR for the same.

[ShauryaAg]

Upon further testing and implementing the above solution does fix the box issue.
However, it still doesn't properly render the experiment tree