Source code for gfw.common.diff

"""General utilities for generating diffs between objects."""

from difflib import ndiff
from typing import Any, Tuple

from rich.columns import Columns
from rich.panel import Panel
from rich.pretty import pretty_repr




def diff_lines(a: str, b: str) -> Tuple[str, str, bool]:
    """Generate a line-by-line diff of two strings with rich markup.

    Args:
        a:
            First multi-line string to compare.
        b:
            Second multi-line string to compare.

    Returns:
        A tuple of (a_diff, b_diff, changed) where:
        - a_diff: The first string annotated with diff highlights.
        - b_diff: The second string annotated with diff highlights.
        - changed: True if any differences were found, False otherwise.
    """
    a_lines, b_lines = a.splitlines(), b.splitlines()
    a_out, b_out = [], []
    changed = False
    for line in ndiff(a_lines, b_lines):
        tag, content = line[0], line[2:]
        if tag == " ":
            a_out.append(f"  {content}")
            b_out.append(f"  {content}")
        elif tag == "-":
            changed = True
            a_out.append(f"[red]- {content}[/red]")
            b_out.append("")  # line not in b
        elif tag == "+":
            changed = True
            a_out.append("")  # line not in a
            b_out.append(f"[green]+ {content}[/green]")

    return "\n".join(a_out), "\n".join(b_out), changed





def compare_items(a: Any, b: Any) -> Tuple[str, str, bool]:
    """Generate a rich diff of two objects' pretty-printed representations.

    Args:
        a:
            First object to compare.
        b:
            Second object to compare.

    Returns:
        The object returned by diff_lines.
    """
    return diff_lines(
        pretty_repr(a, indent_size=4, max_width=20),
        pretty_repr(b, indent_size=4, max_width=20),
    )





def render_diff_panel(left: str, right: str, idx: int) -> Columns:
    """Render side-by-side panels of diff strings for visual comparison.

    Args:
        left:
            The left-side diff string (usually actual output).

        right:
            The right-side diff string (usually expected output).

        idx:
            Index number for labeling the diff panels.

    Returns:
        A rich Columns object containing two Panels side-by-side.
    """
    return Columns(
        [
            Panel(left, title=f"Actual #{idx}", expand=True),
            Panel(right, title=f"Expected #{idx}", expand=True),
        ],
        expand=True,
        equal=True,
    )