Diff

"""Enhanced diff widget for displaying unified diffs."""

from future import annotations

import re from typing import TYPE_CHECKING, Any

from textual.containers import Vertical from textual.widgets import Static

if TYPE_CHECKING: from textual.app import ComposeResult

def _escape_markup(text: str) -> str: """Escape Rich markup characters in text.

Args:
    text: Text that may contain Rich markup

Returns:
    Escaped text safe for Rich rendering
"""
# Escape brackets that could be interpreted as markup
return text.replace("[", r"\[").replace("]", r"\]")

def format_diff_textual(diff: str, max_lines: int | None = 100) -> str: """Format a unified diff with line numbers and colors.

Args:
    diff: Unified diff string
    max_lines: Maximum number of diff lines to show (None for unlimited)

Returns:
    Rich-formatted diff string with line numbers
"""
if not diff:
    return "[dim]No changes detected[/​dim]"

lines = diff.splitlines()

# Compute stats first
additions = sum(1 for ln in lines if ln.startswith("+") and not ln.startswith("+++"))
deletions = sum(1 for ln in lines if ln.startswith("-") and not ln.startswith("---"))

# Find max line number for width calculation
max_line = 0
for line in lines:
    if m := re.match(r"@@ -(\d+)(?:,\d+)? \+(\d+)", line):
        max_line = max(max_line, int(m.group(1)), int(m.group(2)))
width = max(3, len(str(max_line + len(lines))))

formatted = []

# Add stats header
stats_parts = []
if additions:
    stats_parts.append(f"[green]+{additions}[/​green]")
if deletions:
    stats_parts.append(f"[red]-{deletions}[/​red]")
if stats_parts:
    formatted.append(" ".join(stats_parts))
    formatted.append("")  # Blank line after stats

old_num = new_num = 0
line_count = 0

for line in lines:
    if max_lines and line_count >= max_lines:
        formatted.append(f"\n[dim]... ({len(lines) - line_count} more lines)[/​dim]")
        break

    # Skip file headers (--- and +++)
    if line.startswith(("---", "+++")):
        continue

    # Handle hunk headers - just update line numbers, don't display
    if m := re.match(r"@@ -(\d+)(?:,\d+)? \+(\d+)", line):
        old_num, new_num = int(m.group(1)), int(m.group(2))
        continue

    # Handle diff lines - use gutter bar instead of +/​- prefix
    content = line[1:] if line else ""
    escaped_content = _escape_markup(content)

    if line.startswith("-"):
        # Deletion - red gutter bar, subtle red background
        formatted.append(
            f"[red bold]▌[/​red bold][dim]{old_num:>{width}}[/​dim] "
            f"[on #2d1515]{escaped_content}[/​on #2d1515]"
        )
        old_num += 1
        line_count += 1
    elif line.startswith("+"):
        # Addition - green gutter bar, subtle green background
        formatted.append(
            f"[green bold]▌[/​green bold][dim]{new_num:>{width}}[/​dim] "
            f"[on #152d15]{escaped_content}[/​on #152d15]"
        )
        new_num += 1
        line_count += 1
    elif line.startswith(" "):
        # Context line - dim gutter
        formatted.append(f"[dim]│{old_num:>{width}}[/​dim]  {escaped_content}")
        old_num += 1
        new_num += 1
        line_count += 1
    elif line.strip() == "...":
        # Truncation marker
        formatted.append("[dim]...[/​dim]")
        line_count += 1

return "\n".join(formatted)

class EnhancedDiff(Vertical): """Widget for displaying a unified diff with syntax highlighting."""

DEFAULT_CSS = """
EnhancedDiff {
    height: auto;
    padding: 1;
    background: $surface-darken-1;
    border: round $primary;
}

EnhancedDiff .diff-title {
    color: $primary;
    text-style: bold;
    margin-bottom: 1;
}

EnhancedDiff .diff-content {
    height: auto;
}

EnhancedDiff .diff-stats {
    color: $text-muted;
    margin-top: 1;
}
"""

def __init__(
    self,
    diff: str,
    title: str = "Diff",
    max_lines: int | None = 100,
    **kwargs: Any,
) -> None:
    """Initialize the diff widget.

    Args:
        diff: Unified diff string
        title: Title to display above the diff
        max_lines: Maximum number of diff lines to show
        **kwargs: Additional arguments passed to parent
    """
    super().__init__(**kwargs)
    self._diff = diff
    self._title = title
    self._max_lines = max_lines
    self._stats = self._compute_stats()

def _compute_stats(self) -> tuple[int, int]:
    """Compute additions and deletions count.

    Returns:
        Tuple of (additions, deletions)
    """
    additions = 0
    deletions = 0
    for line in self._diff.splitlines():
        if line.startswith("+") and not line.startswith("+++"):
            additions += 1
        elif line.startswith("-") and not line.startswith("---"):
            deletions += 1
    return additions, deletions

def compose(self) -> ComposeResult:
    """Compose the diff widget layout."""
    yield Static(f"[bold cyan]═══ {self._title} ═══[/​bold cyan]", classes="diff-title")

    formatted = format_diff_textual(self._diff, self._max_lines)
    yield Static(formatted, classes="diff-content")

    additions, deletions = self._stats
    if additions or deletions:
        stats_parts = []
        if additions:
            stats_parts.append(f"[green]+{additions}[/​green]")
        if deletions:
            stats_parts.append(f"[red]-{deletions}[/​red]")
        yield Static(" ".join(stats_parts), classes="diff-stats")