import xml.etree.ElementTree as ET
import os
from dataclasses import dataclass
from typing import List, Optional
from pathlib import Path


@dataclass
class SourcedFile:
    layer_name: str
    subfolder: Optional[str]
    files: List[str]


def read_psc_file(psc_file: Path) -> List[SourcedFile]:
    tree = ET.parse(psc_file)
    root = tree.getroot()
    # PSC exports may use a default XML namespace.
    for element in root.iter():
        element.tag = element.tag.rsplit("}", 1)[-1]

    layers = root.findall(".//Layer")

    layer_info_list: List[SourcedFile] = []
    for layer in layers:
        layer_name = layer.attrib.get("Name")
        subfolder = layer.attrib.get("SubFolder")
        # Scripts-Filenames
        scripts = layer.find("Scripts")
        script_names = []
        if scripts is not None:
            for filename in scripts.findall("Filename"):
                name = filename.attrib.get("Name")
                if name:
                    script_names.append(name)

        layer_info_list.append(
            SourcedFile(layer_name=layer_name, subfolder=subfolder, files=script_names)
        )
    return layer_info_list


def get_all_psc_files(root_path: Path) -> list[Path]:
    return sorted(root_path.rglob("*.psc"), key=lambda path: str(path).casefold())


def psc_script_files(psc_file: Path) -> list[Path]:
    """Resolve layer script paths relative to the PSC, preserving load order."""
    def expanded(value):
        return Path(os.path.expandvars(value).replace("\\", "/"))

    paths = []
    for layer in read_psc_file(psc_file):
        folder = layer.subfolder or "."
        base = psc_file.parent / expanded(os.environ.get(folder, folder))
        for name in layer.files:
            filename = expanded(name)
            if not filename.suffix:
                filename = filename.with_suffix(".tcl")
            path = (base / filename).resolve()
            if path.suffix.lower() == ".tcl":
                paths.append(path)
    return paths