"""
Walks a vault root and builds FileRecord objects.

Two jobs: filter out junk (config.IGNORE_*), and make a best-guess starting
date for each real file. That date is explicitly NOT trusted as correct —
you said the metadata is often wrong, so this only has to be a reasonable
starting point that you can freely overwrite, never a claim of truth.
"""

from datetime import datetime
from pathlib import Path
from typing import List

from . import config
from .model import FileRecord


def _is_ignored_file(name: str) -> bool:
    if name in config.TOOL_STATE_FILENAMES:
        return True
    return any(p.match(name) for p in config.IGNORE_FILE_PATTERNS)


def _is_inside_ignored_dir(rel_parts) -> bool:
    return any(
        part in config.IGNORE_DIR_NAMES or part.startswith(".")
        for part in rel_parts[:-1]  # everything except the filename itself
    )


def _best_guess_date(stat) -> str:
    """True creation time isn't reliably available on ext4 via stat() —
    this is a heuristic (earliest of mtime/ctime, or real birthtime if the
    platform exposes it), not an authoritative answer."""
    ts = getattr(stat, "st_birthtime", None)
    if ts is None:
        ts = min(stat.st_mtime, stat.st_ctime)
    return datetime.fromtimestamp(ts).strftime("%Y-%m-%d")


def discover_folders(root: Path) -> List[str]:
    """Every real directory under root, as paths relative to root. This is
    the live, always-current list of possible destinations — it updates
    automatically as your folder structure changes, nothing hardcoded."""
    folders = []
    for p in root.rglob("*"):
        if p.is_dir() and p.name not in config.IGNORE_DIR_NAMES and not p.name.startswith("."):
            folders.append(str(p.relative_to(root)))
    return sorted(folders)


def scan(root: Path) -> List[FileRecord]:
    """Scan root recursively and return one FileRecord per real, non-junk file."""
    records = []
    for p in root.rglob("*"):
        if p.is_dir():
            continue

        rel_parts = p.relative_to(root).parts
        if _is_inside_ignored_dir(rel_parts):
            continue
        if _is_ignored_file(p.name):
            continue

        stat = p.stat()
        fs_date = _best_guess_date(stat)
        name_ok = bool(config.ALREADY_CONVENTIONED.match(p.name))
        near = (not name_ok) and any(
            pat.match(p.name) for pat in config.NEAR_CONVENTION_PATTERNS
        )

        rec = FileRecord(
            path=p,
            root=root,
            filename=p.name,
            ext=p.suffix,
            fs_date=fs_date,
            name_matches_convention=name_ok,
            near_miss=near,
        )
        # Defaults: no change unless you edit something. Files that already
        # match the convention default to "keep name, move only" — see
        # FileRecord.keep_filename for why.
        rec.date_override = fs_date
        rec.dest_folder = rec.current_folder
        rec.keep_filename = name_ok
        records.append(rec)

    return records