"""
Deploy hash manifest at flash root (file_hashes.json).

Updated by led-cli after directory uploads; used to skip unchanged files on
the next deploy. Format: {"version": 1, "algorithm": "sha256", "files": {...}}
"""

import json
import os

MANIFEST_VERSION = 1
MANIFEST_FILENAME = "file_hashes.json"
HASH_ALGO = "sha256"

_SKIP_NAMES = frozenset({MANIFEST_FILENAME, "__pycache__"})
_SKIP_SUFFIXES = (".pyc", ".pyo")


def _normalize_path(path):
    return path.replace("\\", "/").lstrip("/")


def load():
    """Return path -> sha256 hex map, or {} if missing or invalid."""
    try:
        with open(MANIFEST_FILENAME, "r") as f:
            doc = json.load(f)
    except OSError:
        return {}
    if not isinstance(doc, dict):
        return {}
    files = doc.get("files")
    return files if isinstance(files, dict) else {}


def save(files):
    """Write manifest (path keys use forward slashes, no leading slash)."""
    if not isinstance(files, dict):
        files = {}
    doc = {
        "version": MANIFEST_VERSION,
        "algorithm": HASH_ALGO,
        "files": files,
    }
    with open(MANIFEST_FILENAME, "w") as f:
        json.dump(doc, f)


def _hash_file(path):
    import hashlib

    h = hashlib.sha256()
    with open(path, "rb") as f:
        while True:
            chunk = f.read(256)
            if not chunk:
                break
            h.update(chunk)
    return h.hexdigest()


def _walk_dir(base, prefix, out):
    try:
        names = os.listdir(base)
    except OSError:
        return
    for name in names:
        if name in _SKIP_NAMES or name.endswith(_SKIP_SUFFIXES):
            continue
        full = base + "/" + name if base else name
        key = _normalize_path((prefix + "/" + name) if prefix else name)
        try:
            mode = os.stat(full)[0]
        except OSError:
            continue
        if mode & 0x4000:
            _walk_dir(full, key, out)
        else:
            out[key] = _hash_file(full)


def rebuild():
    """Rebuild manifest from root .py files plus patterns/ and lib/ trees."""
    files = {}
    try:
        for name in os.listdir("."):
            if name in _SKIP_NAMES or name.endswith(_SKIP_SUFFIXES):
                continue
            try:
                mode = os.stat(name)[0]
            except OSError:
                continue
            if mode & 0x4000:
                if name in ("patterns", "lib"):
                    _walk_dir(name, name, files)
            else:
                files[_normalize_path(name)] = _hash_file(name)
    except OSError:
        pass
    save(files)
    return files