"""effect_txt.py -- reader for Effects/*.effect (particle-effect definitions).

NOT the brace-block format.  Layout:

    TXT                          # magic first line
    KEY value                    # scalar (number, TRUE/FALSE, "quoted")
    KEY                          # group: KEY on its own line, then
        BEGIN
            ...nested KEY value / groups...
        END

Order matters: 'PARTICLEDATATYPE n' is followed by the CREATION /
VARIATION / OVERLIFE curves that belong to that datatype, and 'MODIFIER'
repeats once per type.  So each level is returned as an ordered list of
[key, value] pairs (value = scalar or nested list).  to_dict() gives a
dict view (repeats -> lists) when order is not needed.

Quirks handled: one file has CRLF; 'NAME "New Emitter"' values contain
spaces; indentation is cosmetic (tabs); the format is line-based.

Stdlib only.
"""
from __future__ import annotations

from typing import Any

from flat_kv import split_tokens, strip_comment
from mars_data import coerce

__all__ = ["parse", "parse_file", "to_dict", "EffectSyntaxError"]

Pairs = list  # list[[key, value]]


class EffectSyntaxError(ValueError):
    pass


def parse(text: str, *, typed: bool = True) -> Pairs:
    lines = text.splitlines()
    if not lines or lines[0].strip() != "TXT":
        raise EffectSyntaxError("missing TXT magic")
    stack: list[Pairs] = [[]]
    pending_key: str | None = None
    for lineno, raw in enumerate(lines[1:], 2):
        line = strip_comment(raw).strip()
        if not line:
            continue
        if line == "BEGIN":
            if pending_key is None:
                raise EffectSyntaxError(f"line {lineno}: BEGIN without a key")
            grp: Pairs = []
            stack[-1].append([pending_key, grp])
            stack.append(grp)
            pending_key = None
            continue
        if line == "END":
            if len(stack) == 1:
                raise EffectSyntaxError(f"line {lineno}: END without BEGIN")
            stack.pop()
            continue
        if pending_key is not None:
            raise EffectSyntaxError(f"line {lineno}: key {pending_key!r} not followed by BEGIN")
        toks = split_tokens(line)
        key = toks[0][0]
        if len(toks) == 1:
            pending_key = key
            continue
        vals = [coerce(t) if (typed and not q) else t for t, q in toks[1:]]
        stack[-1].append([key, vals[0] if len(vals) == 1 else vals])
    if len(stack) != 1:
        raise EffectSyntaxError(f"{len(stack) - 1} unclosed BEGIN group(s)")
    if pending_key is not None:
        raise EffectSyntaxError(f"trailing key {pending_key!r} without BEGIN")
    return stack[0]


def to_dict(pairs: Pairs) -> dict:
    d: dict = {}
    for key, val in pairs:
        if isinstance(val, list) and val and isinstance(val[0], list) and len(val[0]) == 2 and isinstance(val[0][0], str):
            val = to_dict(val)
        if key in d:
            if not isinstance(d[key], list) or not getattr(d[key], "_rep", False):
                d[key] = _Rep([d[key]])
            d[key].append(val)
        else:
            d[key] = val
    return d


class _Rep(list):
    _rep = True


def parse_file(path, **kw) -> Pairs:
    with open(path, "rb") as f:
        return parse(f.read().decode("cp1252"), **kw)