import hashlib
import os
import struct
import tempfile
import unittest
import zipfile
from pathlib import Path

from mhwmm.core.paks import path_hash, pak_name
from mhwmm.core.paths import Paths


def snapshot(root: Path) -> dict:
    """Byte-level picture of a tree: files by hash, symlinks by target, and directories."""
    snap = {}
    for dirpath, dirnames, filenames in os.walk(root):
        for n in dirnames + filenames:
            p = Path(dirpath) / n
            rel = str(p.relative_to(root))
            if p.is_symlink():
                snap[rel] = ("l", os.readlink(p))
            elif p.is_dir():
                snap[rel] = ("d",)
            else:
                snap[rel] = ("f", hashlib.sha256(p.read_bytes()).hexdigest())
    return snap


def make_game(root: Path, ceiling: int = 15) -> Path:
    game = root / "game"
    game.mkdir()
    for chain in ("main", "sub"):
        for n in range(1, ceiling + 1):
            (game / pak_name(chain, n)).write_bytes(f"vanilla-{chain}-{n}".encode())
    (game / "re_chunk_000.pak").write_bytes(b"base")
    (game / "MonsterHunterWilds.exe").write_bytes(b"exe")
    return game


def write_tree(root: Path, files: dict[str, bytes | str]) -> Path:
    for rel, data in files.items():
        p = root / rel
        p.parent.mkdir(parents=True, exist_ok=True)
        p.write_bytes(data if isinstance(data, bytes) else data.encode())
    return root


def make_kpka(paths: list[str]) -> bytes:
    """Minimal KPKA with entries keyed by the path hashes of `paths`."""
    out = b"KPKA" + struct.pack("<BBHII", 4, 0, 0, len(paths), 0)
    for p in paths:
        lo, up = path_hash(p)
        out += struct.pack("<IIQQQQQ", lo, up, 0, 0, 0, 0, 0)
    return out


def make_zip(path: Path, files: dict[str, bytes | str]) -> Path:
    with zipfile.ZipFile(path, "w") as zf:
        for name, data in files.items():
            zf.writestr(name, data)
    return path


class TmpCase(unittest.TestCase):
    def setUp(self):
        self._td = tempfile.TemporaryDirectory()
        self.addCleanup(self._td.cleanup)
        self.tmp = Path(self._td.name)
        self.paths = Paths(self.tmp / "data", self.tmp / "config")
        self.paths.ensure()