"""Classify an extracted mod tree into deployment entries.

Mods are packaged inconsistently, so the payload root is discovered, not assumed.
"""
from __future__ import annotations

import os
import re
from dataclasses import dataclass, field
from pathlib import Path

LOOSE, REFRAMEWORK, PAK, ROOT = "loose", "reframework", "pak", "root"

_JUNK = {".ini", ".txt", ".md", ".png", ".jpg", ".jpeg", ".webp", ".pdf", ".url", ".rtf"}
_SUB_CHAIN = re.compile(r"\.sub_000\.", re.I)
PAK_DEPTH = 2


@dataclass(frozen=True)
class Entry:
    kind: str
    src: Path
    dest: str            # posix path relative to the game dir; "" for PAKs (slot assigned later)
    chain: str = ""      # PAKs only: "main" or "sub"


@dataclass
class Classification:
    entries: list[Entry] = field(default_factory=list)
    ambiguous: list[Path] = field(default_factory=list)   # root-level .dll needing a user decision
    notes: list[str] = field(default_factory=list)

    @property
    def empty(self) -> bool:
        return not self.entries and not self.ambiguous


def pak_chain(name: str) -> str:
    return "sub" if _SUB_CHAIN.search(name) else "main"


def _effective_root(root: Path) -> Path:
    """Descend through single wrapper directories (Mod/Mod/natives/...)."""
    while True:
        kids = [p for p in root.iterdir() if not p.is_symlink()]
        dirs = [p for p in kids if p.is_dir() and not p.name.startswith("__MACOSX")]
        files = [p for p in kids if p.is_file()]
        if len(dirs) == 1 and dirs[0].name.lower() not in ("natives", "reframework", "stm") \
                and all(f.suffix.lower() in _JUNK for f in files):
            root = dirs[0]
        else:
            return root


def _tree(base: Path, prefix: str, kind: str, out: Classification, skip_data: bool = False) -> None:
    for dirpath, dirnames, filenames in os.walk(base):
        rel_dir = Path(dirpath).relative_to(base)
        if skip_data and not rel_dir.parts:
            if any(d.lower() == "data" for d in dirnames):
                out.notes.append("Ignored reframework/data (user settings are never managed)")
            dirnames[:] = [d for d in dirnames if d.lower() != "data"]
        dirnames[:] = sorted(d for d in dirnames if not os.path.islink(os.path.join(dirpath, d)))
        for f in sorted(filenames):
            p = Path(dirpath) / f
            if p.is_symlink():
                continue
            out.entries.append(Entry(kind, p, "/".join([prefix, *rel_dir.parts, f])))


def classify(root: Path, dll_choice: str | None = None) -> Classification:
    """dll_choice for root-level .dll files: 'plugin' | 'root' | 'skip' | None (=> ambiguous)."""
    root = Path(root)
    out = Classification()
    top = _effective_root(root)

    def walk(d: Path, depth: int) -> None:
        for e in sorted(d.iterdir(), key=lambda p: p.name.lower()):
            if e.is_symlink():
                continue
            low = e.name.lower()
            if e.is_dir():
                if low.startswith("__macosx"):
                    continue
                if low == "natives":
                    _tree(e, "natives", LOOSE, out)
                elif low == "reframework":
                    _tree(e, "reframework", REFRAMEWORK, out, skip_data=True)
                elif low == "stm":
                    _tree(e, "natives/STM", LOOSE, out)
                elif depth < PAK_DEPTH:
                    walk(e, depth + 1)
            elif e.is_file():
                if low.endswith(".pak") and depth <= PAK_DEPTH:
                    out.entries.append(Entry(PAK, e, "", pak_chain(e.name)))
                elif depth == 0 and low.endswith(".lua"):
                    out.entries.append(Entry(REFRAMEWORK, e, f"reframework/autorun/{e.name}"))
                elif depth == 0 and low.endswith(".dll"):
                    if dll_choice == "plugin":
                        out.entries.append(Entry(REFRAMEWORK, e, f"reframework/plugins/{e.name}"))
                    elif dll_choice == "root":
                        out.entries.append(Entry(ROOT, e, e.name))
                    elif dll_choice != "skip":
                        if "reframework" in low or "d2d" in low:
                            out.entries.append(Entry(REFRAMEWORK, e, f"reframework/plugins/{e.name}"))
                        else:
                            out.ambiguous.append(e)

    walk(top, 0)
    # the PAK order inside one mod follows its own patch numbers, then name
    return out