# Author: Simon-Pierre Boucher — simon-pierre.boucher@uqo.ca
"""Provider-to-role assignment for the three committees (all_anthropic, all_openai, mixed_random).

``mixed_random`` draws a balanced, seeded permutation per property (seed = global seed + tx_id) so that
the assignment is reproducible and recorded in the transcript.
"""
from __future__ import annotations

import hashlib
import random

from ..config import SEED, load_config

COMMITTEES = ("all_anthropic", "all_openai", "mixed_random")


def pair_for_tier(tier: str | None = None) -> dict[str, str]:
    cfg = load_config("models")
    tier = tier or cfg.get("default_tier", "mid")
    pairs = cfg["cost_matched_pairs"]
    if tier not in pairs:
        raise KeyError(f"tier {tier!r} not in configs/models.yaml cost_matched_pairs")
    return dict(pairs[tier])


def committee_models(committee: str, tier: str | None = None) -> list[str]:
    pair = pair_for_tier(tier)
    if committee == "all_anthropic":
        return [pair["anthropic"]]
    if committee == "all_openai":
        return [pair["openai"]]
    if committee == "mixed_random":
        return [pair["anthropic"], pair["openai"]]
    raise KeyError(f"unknown committee {committee!r} (expected one of {COMMITTEES})")


def assign(roles: list[str], committee: str, seed: int = SEED, tx_id: str = "", tier: str | None = None) -> dict[str, str]:
    """role id -> model id. Deterministic given (roles, committee, seed, tx_id, tier)."""
    pair = pair_for_tier(tier)
    if committee == "all_anthropic":
        return {r: pair["anthropic"] for r in roles}
    if committee == "all_openai":
        return {r: pair["openai"] for r in roles}
    if committee != "mixed_random":
        raise KeyError(f"unknown committee {committee!r} (expected one of {COMMITTEES})")
    n = len(roles)
    vendors = ["anthropic", "openai"] * (n // 2 + 1)
    vendors = vendors[:n]  # balanced: ceil(n/2) anthropic, floor(n/2) openai before shuffling
    rng = random.Random(int(hashlib.sha256(f"{seed}|{tx_id}".encode()).hexdigest()[:16], 16))
    rng.shuffle(vendors)
    if n % 2 == 1 and rng.random() < 0.5:  # the odd slot goes to either vendor with equal probability
        vendors = ["openai" if v == "anthropic" else "anthropic" for v in vendors]
    return {r: pair[v] for r, v in zip(roles, vendors)}