"""TODO scanner for source code files."""

import re
from dataclasses import dataclass
from pathlib import Path
from typing import Dict, List


@dataclass
class TodoItem:
    file: Path
    line: int
    tag: str
    text: str


# Regex for common comment prefixes followed by TODO/FIXME/HACK/XXX
_TODO_RE = re.compile(
    r"(?:^\s*(?:#|//|/\*|\*|<!--)\s*)"  # comment prefix
    r"(TODO|FIXME|HACK|XXX)"  # tag
    r"[\s:]*"  # separator
    r"(.*?)"  # text
    r"(?:\s*\*/\s*|\s*-->\s*)?$",  # optional block-comment / html close
    re.IGNORECASE,
)

# File extensions to scan
_SCAN_EXTENSIONS = {
    ".py",
    ".js",
    ".jsx",
    ".ts",
    ".tsx",
    ".java",
    ".c",
    ".cc",
    ".cpp",
    ".h",
    ".hpp",
    ".rs",
    ".go",
    ".rb",
    ".sh",
    ".bash",
    ".zsh",
    ".pl",
    ".pm",
    ".swift",
    ".kt",
    ".scala",
    ".r",
    ".lua",
    ".php",
    ".cs",
    ".fs",
    ".fsx",
    ".md",
    ".yaml",
    ".yml",
    ".json",
    ".toml",
    ".ini",
    ".cfg",
    ".conf",
    ".dockerfile",
    ".makefile",
    ".mk",
}

_SKIP_DIRS = {
    ".git",
    ".hg",
    ".svn",
    "__pycache__",
    ".pytest_cache",
    ".mypy_cache",
    "node_modules",
    "vendor",
    "target",
    "build",
    "dist",
    ".next",
    ".nuxt",
    ".terraform",
    ".venv",
    "venv",
    "env",
    ".idea",
    ".vscode",
    ".vs",
    "out",
    "coverage",
    "site-packages",
    "egg-info",
}


def _should_scan(path: Path) -> bool:
    ext = path.suffix.lower()
    if ext in _SCAN_EXTENSIONS:
        return True
    if path.name.lower().startswith("dockerfile"):
        return True
    if path.name.lower().startswith("makefile"):
        return True
    return False


def scan_directory(project_path: Path) -> List[TodoItem]:
    """Recursively scan a directory for TODO comments."""
    todos: List[TodoItem] = []
    for entry in project_path.rglob("*"):
        if not entry.is_file():
            continue
        # Skip hidden dirs
        try:
            relative = entry.relative_to(project_path)
        except ValueError:
            relative = entry
        if any(
            part in _SKIP_DIRS or part.startswith(".") for part in relative.parts[:-1]
        ):
            continue
        if not _should_scan(entry):
            continue
        todos.extend(_scan_file(entry, project_path))
    # Sort by file path then line number
    todos.sort(key=lambda t: (str(t.file), t.line))
    return todos


def _scan_file(file_path: Path, project_path: Path) -> List[TodoItem]:
    todos: List[TodoItem] = []
    try:
        with open(file_path, "r", encoding="utf-8", errors="replace") as f:
            lines = f.readlines()
    except (OSError, UnicodeDecodeError):
        return todos

    for lineno, raw_line in enumerate(lines, start=1):
        match = _TODO_RE.search(raw_line)
        if match:
            tag = match.group(1).upper()
            text = match.group(2).strip()
            if text:
                rel_file = file_path.relative_to(project_path)
                todos.append(TodoItem(file=rel_file, line=lineno, tag=tag, text=text))
    return todos


def group_by_file(todos: List[TodoItem]) -> Dict[Path, List[TodoItem]]:
    """Group TODO items by their file path."""
    groups: Dict[Path, List[TodoItem]] = {}
    for t in todos:
        groups.setdefault(t.file, []).append(t)
    return groups


def count_tags(todos: List[TodoItem]) -> Dict[str, int]:
    """Count occurrences of each tag."""
    counts: Dict[str, int] = {}
    for t in todos:
        counts[t.tag] = counts.get(t.tag, 0) + 1
    return counts