"""Turn a catalog row into the text document the embedding model reads."""
import numpy as np

KEEP_CATEGORIES = {
    "Single-player", "Multi-player", "Co-op", "Online Co-op", "LAN Co-op", "Shared/Split Screen Co-op",
    "PvP", "Online PvP", "Shared/Split Screen PvP", "MMO", "VR Support", "VR Only", "Cross-Platform Multiplayer",
}


def build_doc(row, rng: np.random.Generator | None = None, drop_tags: bool = False, max_tags: int = 15) -> str:
    """Deterministic when rng is None. With rng, returns a randomly degraded view for contrastive training."""
    aug = rng is not None
    tags = list(row["tags"])[:max_tags]
    if drop_tags or (aug and rng.random() < 0.5):
        tags = []
    elif aug and tags:
        keep = rng.random(len(tags)) >= 0.3
        tags = [t for t, k in zip(tags, keep) if k]
    genres = list(row["genres"])
    cats = [c for c in row["categories"] if c in KEEP_CATEGORIES][:5]
    desc = (row["short"] + " " + row["about"]).strip()
    if aug and desc:
        if rng.random() < 0.3 and (tags or genres):
            desc = ""
        else:
            words = desc.split()
            cut = int(len(words) * rng.uniform(0.3, 1.0)) if len(words) > 20 else len(words)
            desc = " ".join(words[:cut])

    parts = [row["name"] + "."]
    if genres:
        parts.append("Genres: " + ", ".join(genres) + ".")
    if tags:
        parts.append("Tags: " + ", ".join(tags) + ".")
    if cats:
        parts.append("Modes: " + ", ".join(cats) + ".")
    if len(row["developers"]):
        parts.append("Developer: " + ", ".join(list(row["developers"])[:2]) + ".")
    if desc:
        parts.append(desc)
    return " ".join(parts)