from __future__ import annotations

import hashlib
import os
from collections.abc import Iterable
from pathlib import Path
from typing import TypedDict

from .models import DEFAULT_CODE_EXTENSIONS


class Aggregate(TypedDict):
    file_count: int
    total_bytes: int


class DataSummary(Aggregate):
    by_extension: dict[str, Aggregate]
    by_top_level: dict[str, Aggregate]


_EXCLUDED_DIRECTORY_NAMES = frozenset(
    {
        ".cache",
        ".git",
        ".hermes_tmp",
        ".mypy_cache",
        ".pytest_cache",
        ".ruff_cache",
        ".tox",
        ".venv",
        "__pycache__",
        "cache",
        "data",
        "debug",
        "evidence",
        "log",
        "logs",
        "node_modules",
        "reports",
        "runtime",
        "state",
        "tmp",
        "var",
    }
)
_SENSITIVE_DIRECTORY_MARKERS = ("cookie", "profile")
_SENSITIVE_FILE_NAMES = frozenset(
    {
        ".env",
        "credentials.json",
        "secrets.json",
        "service-account.json",
        "service_account.json",
    }
)
_SENSITIVE_FILE_MARKERS = ("cookie", "credential", "secret", "token")


def _is_excluded_directory(name: str) -> bool:
    normalized = name.casefold()
    return normalized in _EXCLUDED_DIRECTORY_NAMES or any(
        marker in normalized for marker in _SENSITIVE_DIRECTORY_MARKERS
    )


def _is_sensitive_file(name: str) -> bool:
    normalized = name.casefold()
    if normalized in _SENSITIVE_FILE_NAMES or normalized.startswith(".env."):
        return True
    stem = Path(normalized).stem
    return any(marker in stem for marker in _SENSITIVE_FILE_MARKERS)


def _walk_files(
    root: Path,
    *,
    exclude_runtime: bool,
    excluded_roots: frozenset[Path] = frozenset(),
) -> Iterable[Path]:
    if not root.is_dir():
        raise FileNotFoundError(f"inventory root is not a directory: {root}")
    for directory, dirnames, filenames in os.walk(root, followlinks=False):
        if exclude_runtime:
            dirnames[:] = sorted(
                name
                for name in dirnames
                if not _is_excluded_directory(name)
                and not (Path(directory) / name).is_symlink()
                and (Path(directory) / name).resolve(strict=False) not in excluded_roots
            )
        else:
            dirnames[:] = sorted(
                name for name in dirnames if not (Path(directory) / name).is_symlink()
            )
        for filename in sorted(filenames):
            path = Path(directory) / filename
            if not path.is_symlink():
                yield path


def _sha256(path: Path) -> str:
    digest = hashlib.sha256()
    with path.open("rb") as stream:
        for chunk in iter(lambda: stream.read(1024 * 1024), b""):
            digest.update(chunk)
    return digest.hexdigest()


def collect_code_inventory(
    root: Path,
    *,
    allowed_extensions: frozenset[str] = DEFAULT_CODE_EXTENSIONS,
    excluded_roots: Iterable[Path] = (),
) -> list[dict[str, str | int]]:
    """Hash code-like files without retaining file contents or config values."""

    root = Path(root)
    normalized_extensions = frozenset(extension.casefold() for extension in allowed_extensions)
    normalized_excluded_roots = frozenset(
        Path(excluded_root).resolve(strict=False) for excluded_root in excluded_roots
    )
    inventory: list[dict[str, str | int]] = []
    for path in _walk_files(
        root, exclude_runtime=True, excluded_roots=normalized_excluded_roots
    ):
        if path.suffix.casefold() not in normalized_extensions or _is_sensitive_file(path.name):
            continue
        stat = path.stat()
        inventory.append(
            {
                "relative_path": path.relative_to(root).as_posix(),
                "size_bytes": stat.st_size,
                "mtime_ns": stat.st_mtime_ns,
                "sha256": _sha256(path),
            }
        )
    return sorted(inventory, key=lambda item: str(item["relative_path"]).casefold())


def _increment(target: dict[str, Aggregate], key: str, size: int) -> None:
    aggregate = target.setdefault(key, {"file_count": 0, "total_bytes": 0})
    aggregate["file_count"] += 1
    aggregate["total_bytes"] += size


def collect_data_summary(root: Path) -> DataSummary:
    """Summarize a data tree without exposing names, paths, times, hashes, or values."""

    root = Path(root)
    summary: DataSummary = {
        "file_count": 0,
        "total_bytes": 0,
        "by_extension": {},
        "by_top_level": {},
    }
    for path in _walk_files(root, exclude_runtime=False):
        size = path.stat().st_size
        relative = path.relative_to(root)
        top_level = relative.parts[0] if len(relative.parts) > 1 else "."
        extension = path.suffix.casefold() or "[no_extension]"
        summary["file_count"] += 1
        summary["total_bytes"] += size
        _increment(summary["by_extension"], extension, size)
        _increment(summary["by_top_level"], top_level, size)
    summary["by_extension"] = dict(sorted(summary["by_extension"].items()))
    summary["by_top_level"] = dict(sorted(summary["by_top_level"].items()))
    return summary