from __future__ import annotations

import io
import xml.etree.ElementTree as ET
from collections.abc import Iterable
from dataclasses import dataclass

DLC = {
    "royalty": ("ludeon.rimworld.royalty", "Royalty"),
    "ideology": ("ludeon.rimworld.ideology", "Ideology"),
    "biotech": ("ludeon.rimworld.biotech", "Biotech"),
    "anomaly": ("ludeon.rimworld.anomaly", "Anomaly"),
    "odyssey": ("ludeon.rimworld.odyssey", "Odyssey"),
}
BASE_GAME = ("ludeon.rimworld", "Core")


@dataclass(frozen=True)
class ModListItem:
    package_id: str
    workshop_id: str
    name: str


def core_items(selected_dlc: Iterable[str]) -> list[ModListItem]:
    result = [ModListItem(BASE_GAME[0], "0", BASE_GAME[1])]
    normalized = {value.strip().lower() for value in selected_dlc}
    for key, (package_id, name) in DLC.items():
        if key in normalized:
            result.append(ModListItem(package_id, "0", name))
    return result


def workshop_items(rows: Iterable[dict]) -> list[ModListItem]:
    result: list[ModListItem] = []
    for row in rows:
        if row.get("status") != "ready" or not row.get("package_id"):
            continue
        # The Workshop id is the correct RimWorld modSteamIds value. The old loader
        # sometimes substituted About.xml's steamAppId, which can be the game app id.
        result.append(
            ModListItem(
                package_id=str(row["package_id"]),
                workshop_id=str(row["workshop_id"]),
                name=str(
                    row.get("display_name") or row.get("title") or row["package_id"]
                ),
            )
        )
    return result


def deduplicate(items: Iterable[ModListItem]) -> list[ModListItem]:
    result: list[ModListItem] = []
    seen_packages: set[str] = set()
    seen_workshop_ids: set[str] = set()
    for item in items:
        package_key = item.package_id.lower()
        if package_key in seen_packages:
            continue
        if item.workshop_id != "0" and item.workshop_id in seen_workshop_ids:
            continue
        seen_packages.add(package_key)
        if item.workshop_id != "0":
            seen_workshop_ids.add(item.workshop_id)
        result.append(item)
    return result


def parse_active_mods(xml_bytes: bytes) -> list[ModListItem]:
    if len(xml_bytes) > 5 * 1024 * 1024:
        raise ValueError("ModsConfig.xml is larger than 5 MB")
    try:
        root = ET.fromstring(xml_bytes)
    except ET.ParseError as error:
        raise ValueError(f"ModsConfig.xml is invalid: {error}") from error
    active = root.find("activeMods")
    if active is None:
        raise ValueError("ModsConfig.xml has no activeMods section")
    items: list[ModListItem] = []
    for entry in active.findall("li"):
        package_id = (entry.text or "").strip()
        if package_id:
            items.append(ModListItem(package_id, "0", package_id))
    return items


def _append_list(parent: ET.Element, name: str, values: Iterable[str]) -> None:
    element = ET.SubElement(parent, name)
    for value in values:
        ET.SubElement(element, "li").text = value


def generate_rml(items: Iterable[ModListItem], game_version: str) -> bytes:
    normalized = deduplicate(items)
    root = ET.Element("savedModList")
    meta = ET.SubElement(root, "meta")
    ET.SubElement(meta, "gameVersion").text = game_version
    _append_list(meta, "modIds", (item.package_id for item in normalized))
    _append_list(meta, "modSteamIds", (item.workshop_id for item in normalized))
    _append_list(meta, "modNames", (item.name for item in normalized))

    mod_list = ET.SubElement(root, "modList")
    _append_list(mod_list, "ids", (item.package_id for item in normalized))
    _append_list(mod_list, "names", (item.name for item in normalized))

    ET.indent(root, space="\t")
    output = io.BytesIO()
    ET.ElementTree(root).write(output, encoding="utf-8", xml_declaration=True)
    return output.getvalue()