"""Build canonical filenames: ``Title (Region) (tags) (Serial).iso``.

Revision (``(v1.03)``), disc (``(Disc 1)``) and edition tags are preserved;
language tags (``(En,Fr,De)``) are dropped; leading articles are moved back in
front (``Sims 2, The`` -> ``The Sims 2``).
"""
import re

_ILLEGAL = re.compile(r'[<>:"/\\|?*\x00-\x1f]')
_TAG_RE = re.compile(r"\s*\(([^()]*)\)\s*$")
_ARTICLE_RE = re.compile(r"^(.+),\s*(The|A|An)(?:\s+-\s+(.+))?$", re.IGNORECASE)

_LANG_CODES = {
    "en", "fr", "de", "es", "it", "nl", "pt", "sv", "no", "da", "fi",
    "ja", "ko", "zh", "pl", "ru", "el", "tr", "cs", "hu", "hi", "ar", "th",
}


def _is_language_tag(inner):
    parts = [p.strip().lower() for p in inner.split(",")]
    return bool(parts) and all(p in _LANG_CODES for p in parts)


def _split_tags(name):
    """Split trailing parenthetical tags; keep non-language tags, drop languages."""
    title = name
    kept = []
    while True:
        m = _TAG_RE.search(title)
        if not m:
            break
        inner = m.group(1).strip()
        if _is_language_tag(inner):
            title = title[: m.start()]
        else:
            kept.insert(0, f"({inner})")
            title = title[: m.start()]
    return title.strip(), kept


def region_from_name(name):
    """Extract the region from a release name (first non-language tag).

    Used when a DAT leaves the region field empty and embeds it in the name
    (e.g. ``Oceans 11 (Japan, Europe)``).
    """
    _, kept = _split_tags(str(name))
    if not kept:
        return ""
    inner = kept[0][1:-1].strip()
    return inner


def _reorder_article(title):
    m = _ARTICLE_RE.match(title)
    if m:
        prefix, article, suffix = m.group(1), m.group(2), m.group(3)
        result = f"{article} {prefix}"
        if suffix:
            result += f" - {suffix}"
        return result
    return title


def canonical_name(release, serial, ext=".iso"):
    name = release["name"]
    region = release.get("region")
    if region:
        for r in [x.strip() for x in region.split(",") if x.strip()]:
            name = re.sub(rf"\s*\(\s*{re.escape(r)}\s*\)", "", name, flags=re.IGNORECASE)
    title, tags = _split_tags(name)
    title = _reorder_article(title)
    parts = [title]
    if region and region != "World":
        parts.append(f"({region})")
    parts.extend(tags)
    if serial:
        parts.append(f"({serial})")
    name = _ILLEGAL.sub(" ", " ".join(parts)).strip()
    name = re.sub(r"\s+", " ", name)
    return f"{name}{ext}"