import heapq
import warnings
from functools import lru_cache
from typing import Dict, List, Set, Tuple, Any
from dataclasses import dataclass, field

from constants import (
    TIER_ORDER, TIER_BPW, GGUF_OVERHEAD_FACTOR, CLASS_MAX_TIER,
    CAN_Q3, ALLOW_LOWER_FLOOR, MTP_DEPLOY_TIER, get_tensor_class, get_tensor_type,
    is_mtp_tensor,
)

# Выносим делитель в константу (8 бит * 1024 байт * 1024 кбайт)
BITS_IN_MIB = 8 * 1024 * 1024.0

# Предвычисляем множители размеров для каждого тира (ускорение математики)
TIER_SIZE_MULTIPLIER = {
    tier: (bpw / BITS_IN_MIB) * GGUF_OVERHEAD_FACTOR 
    for tier, bpw in TIER_BPW.items()
}

# K-quants используют блоки по 256 элементов и требуют выравнивания (padding) 3D-тензоров MoE
K_QUANTS = {"Q3_K", "Q4_K", "Q5_K", "Q6_K"}
MOE_PAD_TYPES = {"ffn_gate_exps", "ffn_up_exps", "ffn_down_exps", "ffn_down"}

MSE_BPW = {
    "IQ1_S": 1.5625, "IQ2_XXS": 2.0625, "IQ2_XS": 2.3125,
    "IQ2_S": 2.5,
    "IQ3_XXS": 3.0625,
    "Q3_K": 3.4375, "IQ3_S": 3.44,
    "IQ4_XS": 4.25, "IQ4_NL": 4.25, "Q4_K": 4.50,
    "Q5_K": 5.50, "Q6_K": 6.5625, "Q8_0": 8.50, "F16": 16.0,
}

@dataclass(order=True, slots=True)
class UpgradeItem:
    """Элемент очереди апгрейдов. Сравнивается только по neg_utility."""
    neg_utility: float
    group_id: int = field(compare=False)
    next_tier: str = field(compare=False)
    cost_delta: float = field(compare=False)


def _tier_index(tier: str) -> int:
    if tier not in TIER_ORDER:
        raise ValueError(f"Unknown tier: {tier}")
    return TIER_ORDER.index(tier)

def _tier_at(idx: int) -> str:
    if not (0 <= idx < len(TIER_ORDER)):
        raise IndexError(f"Tier index {idx} out of range")
    return TIER_ORDER[idx]

def _size_mib(tier: str, n_elements: int) -> float:
    """Размер тензора в MiB с учётом оверхеда GGUF."""
    if n_elements <= 0:
        return 0.0
    return n_elements * TIER_SIZE_MULTIPLIER.get(tier, 0.0)

@lru_cache(maxsize=64)
def _mse_delta(cur_tier: str, next_tier: str) -> float:
    return (2 ** (-2 * MSE_BPW[cur_tier])) - (2 ** (-2 * MSE_BPW[next_tier]))

def _push_upgrade(group_id: int,
                  group_registry: Dict[int, Tuple[List[str], int, int]],
                  assignments: Dict[str, str],
                  tensor_importance: Dict[str, float],
                  upgrade_queue: List[UpgradeItem],
                  importance_table: Dict[str, Any]):
    
    # Храним 3 элемента: имена, реальный размер, размер с padding
    g_names, g_elements, g_elements_padded = group_registry[group_id]
    rep_name = g_names[0]
    cur_tier = assignments[rep_name]
    cur_idx = _tier_index(cur_tier)

    rep_info = importance_table.get(rep_name, {})
    ttype = rep_info["type"] if "type" in rep_info else get_tensor_type(rep_name)
    cls = get_tensor_class(ttype)
    max_tier = CLASS_MAX_TIER.get(cls, "Q8_0")

    if cur_idx >= _tier_index(max_tier) or cur_idx >= len(TIER_ORDER) - 1:
        return

    next_tier = _tier_at(cur_idx + 1)
    
    # Выбираем размер в зависимости от того, относится ли тир к K-quants
    cur_size_g = g_elements_padded if cur_tier in K_QUANTS else g_elements
    next_size_g = g_elements_padded if next_tier in K_QUANTS else g_elements
    
    cost_delta = _size_mib(next_tier, next_size_g) - _size_mib(cur_tier, cur_size_g)

    quality_delta = _mse_delta(cur_tier, next_tier)
    if quality_delta <= 0:
        return

    if cost_delta == 0:
        utility_per_mb = float('inf')
    elif cost_delta < 0:
        return 
    else:
        total_g_imp = sum(tensor_importance.get(n, 0) for n in g_names)
        utility_per_mb = (total_g_imp * quality_delta) / cost_delta

    heapq.heappush(upgrade_queue, UpgradeItem(-utility_per_mb, group_id, next_tier, cost_delta))


def compute_initial_assignments(non_mtp_names: Set[str], mtp_names: Set[str], 
                                importance_table: Dict, allow_q3: bool, is_qat: bool = False) -> Dict[str, str]:
    assignments = {name: MTP_DEPLOY_TIER for name in mtp_names}

    for name in non_mtp_names:
        rep_info = importance_table.get(name, {})
        has_imatrix = "importance_mean" in rep_info
        ttype = rep_info["type"] if "type" in rep_info else get_tensor_type(name)
        cls = get_tensor_class(ttype)
        
        if cls in ("norms", "ssm_params"):
            assignments[name] = "F16"
        elif cls == "embd":
            assignments[name] = "Q4_K" if is_qat else "Q5_K"
        else:
            base_floor = ("Q4_K" if cls == "attn_proj" else "IQ4_XS") if is_qat else "Q4_K"
            if allow_q3 and cls in CAN_Q3 and has_imatrix:
                assignments[name] = ALLOW_LOWER_FLOOR
            else:
                assignments[name] = base_floor
            
    return assignments


def build_groups(tied_groups: List[List[str]], non_mtp_names: Set[str], 
                 ne_map: Dict[str, int], padded_ne_map: Dict[str, int]) -> Dict[int, Tuple[List[str], int, int]]:
    group_registry = {}
    assigned_tensors = set()
    
    for group_idx, group in enumerate(tied_groups):
        clean_group = [n for n in group if n in non_mtp_names]
        if clean_group:
            g_elements = sum(ne_map.get(n, 0) for n in clean_group)
            g_elements_padded = sum(padded_ne_map.get(n, 0) for n in clean_group)
            group_registry[group_idx] = (clean_group, g_elements, g_elements_padded)
            assigned_tensors.update(clean_group)

    unassigned_tensors = non_mtp_names - assigned_tensors
    next_group_idx = len(group_registry)
    
    for name in unassigned_tensors:
        group_registry[next_group_idx] = ([name], ne_map.get(name, 0), padded_ne_map.get(name, 0))
        next_group_idx += 1
            
    return group_registry


def optimal_classify(importance_table: dict, tied_groups: list, model: dict, 
                     target_size_mib: float, allow_q3: bool = False) -> Tuple[dict, dict]:
    if target_size_mib <= 0:
        raise ValueError("target_size_mib must be positive")

    features = model.get("features", {})
    has_mtp = features.get("has_mtp", False)
    n_layers = features.get("n_layers", 31)
    is_qat = features.get("is_qat", False)
    model_tensors = model.get("tensors", {})

    ne_map = {k: v["n_elements"] for k, v in model_tensors.items()}
    for tname, info in importance_table.items():
        if tname not in ne_map:
            ne_map[tname] = info["n_elements"]

    # --- Вычисление MoE Padding (Целочисленное выравнивание) ---
    moe_d_ff = features.get("moe_intermediate_size", 0)
    padded_ne_map = dict(ne_map)
    if moe_d_ff > 0 and moe_d_ff % 256 != 0:
        aligned_d_ff = ((moe_d_ff + 255) // 256) * 256
        for name, n_el in ne_map.items():
            ttype = importance_table.get(name, {}).get("type", get_tensor_type(name))
            if ttype in MOE_PAD_TYPES:
                padded_ne_map[name] = (n_el // moe_d_ff) * aligned_d_ff
    # -----------------------------------------------------------

    all_names = set(ne_map.keys())
    mtp_names = {n for n in all_names if is_mtp_tensor(n, n_layers)} if has_mtp else set()
    non_mtp_names = all_names - mtp_names

    tensor_importance = {}
    for name in non_mtp_names:
        raw_imp = importance_table.get(name, {}).get("importance_mean", 0.0)
        tensor_importance[name] = raw_imp

    assignments = compute_initial_assignments(non_mtp_names, mtp_names, importance_table, allow_q3, is_qat)
    group_registry = build_groups(tied_groups, non_mtp_names, ne_map, padded_ne_map)

    mtp_cost = sum(_size_mib(MTP_DEPLOY_TIER, ne_map.get(n, 0)) for n in mtp_names)
    effective_target = target_size_mib - mtp_cost
    
    current_size = sum(
        _size_mib(assignments[n], padded_ne_map.get(n, ne_map.get(n, 0)) if assignments[n] in K_QUANTS else ne_map.get(n, 0))
        for n in non_mtp_names
    )

    if current_size > effective_target:
        warnings.warn(f"Initial size {current_size:.1f} MiB already exceeds target {effective_target:.1f} MiB", RuntimeWarning)

    upgrade_queue = []
    for g_id in group_registry:
        _push_upgrade(g_id, group_registry, assignments, tensor_importance, upgrade_queue, importance_table)

    while upgrade_queue:
        item = heapq.heappop(upgrade_queue)
        g_id, next_tier, cost_delta = item.group_id, item.next_tier, item.cost_delta
        
        if cost_delta > 0 and current_size + cost_delta > effective_target:
            continue
            
        for n in group_registry[g_id][0]:
            assignments[n] = next_tier
        current_size += cost_delta
        
        _push_upgrade(g_id, group_registry, assignments, tensor_importance, upgrade_queue, importance_table)

    return assignments, padded_ne_map


def compute_stats(assignments: dict, ne_map: dict = None, padded_ne_map: dict = None) -> dict:
    """Собирает статистику по тирам с точным учётом K_QUANTS padding."""
    stats = {"by_tier_count": {}, "by_tier_mib": {}, "total_mib": 0.0, "tensor_count": 0}
    for name, tier in assignments.items():
        if not isinstance(tier, str):
            continue
        stats["tensor_count"] += 1
        stats["by_tier_count"][tier] = stats["by_tier_count"].get(tier, 0) + 1
        
        if ne_map:
            if padded_ne_map and tier in K_QUANTS:
                elements = padded_ne_map.get(name, ne_map.get(name, 0))
            else:
                elements = ne_map.get(name, 0)
                
            size = _size_mib(tier, elements)
            stats["by_tier_mib"][tier] = stats["by_tier_mib"].get(tier, 0.0) + size
            stats["total_mib"] += size
            
    return stats