"""
Source code feed — reads engine/*.py and emits non-blank, non-comment lines
as scroll items. Used by --code mode.
Depends on: nothing (stdlib only).
"""

import ast
from pathlib import Path

_ENGINE_DIR = Path(__file__).resolve().parent


def _scope_map(source: str) -> dict[int, str]:
    """Return {line_number: scope_label} for every line in source.

    Nodes are sorted by range size descending so inner scopes overwrite
    outer ones, guaranteeing the narrowest enclosing scope wins.
    """
    try:
        tree = ast.parse(source)
    except SyntaxError:
        return {}

    nodes = []
    for node in ast.walk(tree):
        if isinstance(node, (ast.FunctionDef, ast.AsyncFunctionDef, ast.ClassDef)):
            end = getattr(node, "end_lineno", node.lineno)
            span = end - node.lineno
            nodes.append((span, node))

    # Largest range first → inner scopes overwrite on second pass
    nodes.sort(key=lambda x: x[0], reverse=True)

    scope = {}
    for _, node in nodes:
        end = getattr(node, "end_lineno", node.lineno)
        if isinstance(node, ast.ClassDef):
            label = node.name
        else:
            label = f"{node.name}()"
        for ln in range(node.lineno, end + 1):
            scope[ln] = label

    return scope


def fetch_code():
    """Read engine/*.py and return (items, line_count, 0).

    Each item is (text, src, ts) where:
      text  = the code line (rstripped, indentation preserved)
      src   = enclosing function/class name, e.g. 'stream()' or '<module>'
      ts    = dotted module path, e.g. 'engine.scroll'
    """
    items = []
    for path in sorted(_ENGINE_DIR.glob("*.py")):
        module = f"engine.{path.stem}"
        source = path.read_text(encoding="utf-8")
        scope = _scope_map(source)
        for lineno, raw in enumerate(source.splitlines(), start=1):
            stripped = raw.strip()
            if not stripped or stripped.startswith("#"):
                continue
            label = scope.get(lineno, "<module>")
            items.append((raw.rstrip(), label, module))

    return items, len(items), 0