import re

from services.hwfit.models import (
    params_b, estimate_memory_gb, infer_use_case,
    get_models, is_prequantized, _active_params_b, QUANT_BYTES_PER_PARAM,
    QUANT_SPEED_MULT, QUANT_QUALITY_PENALTY,
)

GPU_BANDWIDTH = {
    "5090": 1792, "5080": 960, "5070 ti": 896, "5070": 672, "5060 ti": 448, "5060": 256,
    "4090": 1008, "4080 super": 736, "4080": 717, "4070 ti super": 672, "4070 ti": 504, "4070 super": 504, "4070": 504, "4060 ti": 288, "4060": 272,
    "3090 ti": 1008, "3090": 936, "3080 ti": 912, "3080": 760, "3070 ti": 608, "3070": 448, "3060 ti": 448, "3060": 360,
    "2080 ti": 616, "2080 super": 496, "2080": 448, "2070 super": 448, "2070": 448, "2060 super": 448, "2060": 336,
    "1660 ti": 288, "1660 super": 336, "1660": 192, "1650 super": 192, "1650": 128,
    "h100 sxm": 3350, "h100": 2039, "h200": 4800, "a100 sxm": 2039, "a100": 1555,
    "l40s": 864, "l40": 864, "l4": 300, "a10g": 600, "a10": 600, "t4": 320,
    "v100 sxm": 900, "v100": 897, "a6000": 768, "a5000": 768, "a4000": 448,
    "7900 xtx": 960, "7900 xt": 800, "7900 gre": 576, "7800 xt": 624, "7700 xt": 432, "7600": 288,
    "6950 xt": 576, "6900 xt": 512, "6800 xt": 512, "6800": 512, "6700 xt": 384, "6600 xt": 256, "6600": 224,
    "mi300x": 5300, "mi300": 5300, "mi250x": 3277, "mi250": 3277, "mi210": 1638, "mi100": 1229,
    "9070 xt": 624, "9070": 488,
}

# Pre-sort keys by length descending for correct substring matching
_BW_KEYS_SORTED = sorted(GPU_BANDWIDTH.keys(), key=len, reverse=True)

FALLBACK_K = {"cuda": 220, "rocm": 180, "cpu_x86": 70, "cpu_arm": 90}

USE_CASE_WEIGHTS = {
    "general":    (0.45, 0.30, 0.15, 0.10),
    "coding":     (0.50, 0.20, 0.15, 0.15),
    "reasoning":  (0.55, 0.15, 0.15, 0.15),
    "chat":       (0.40, 0.35, 0.15, 0.10),
    "multimodal": (0.50, 0.20, 0.15, 0.15),
    "embedding":  (0.30, 0.40, 0.20, 0.10),
    "tts":        (0.40, 0.35, 0.15, 0.10),
    "stt":        (0.40, 0.35, 0.15, 0.10),
}

SPEED_TARGET = {
    "general": 40, "coding": 40, "multimodal": 40, "chat": 40,
    "reasoning": 25, "embedding": 200, "tts": 40, "stt": 40,
}

CONTEXT_TARGET = {
    "general": 4096, "chat": 4096, "coding": 8192,
    "reasoning": 8192, "multimodal": 4096, "embedding": 512,
    "tts": 2048, "stt": 2048,
}


def _lookup_bandwidth(gpu_name):
    if not gpu_name:
        return None
    gn = gpu_name.lower()
    for key in _BW_KEYS_SORTED:
        if key in gn:
            return GPU_BANDWIDTH[key]
    return None


def _estimate_speed(model, quant, run_mode, system):
    """Estimate tok/s. Uses active params for MoE (only active experts run per token)."""
    pb = _active_params_b(model)
    is_moe = model.get("is_moe", False)
    bw = _lookup_bandwidth(system.get("gpu_name"))
    backend = system.get("backend", "cpu_x86")

    if bw and run_mode in ("gpu", "cpu_offload"):
        bpp = QUANT_BYTES_PER_PARAM.get(quant, 0.5)
        model_gb = pb * bpp
        if model_gb <= 0:
            return 0.0
        efficiency = 0.55
        raw_tps = (bw / model_gb) * efficiency
        if run_mode == "cpu_offload":
            mode_factor = 0.5
        elif is_moe:
            mode_factor = 0.8
        else:
            mode_factor = 1.0
        return raw_tps * mode_factor

    k = FALLBACK_K.get(backend, 70)
    if pb <= 0:
        return 0.0
    sm = QUANT_SPEED_MULT.get(quant, 1.0)
    return k / pb * sm


def _quality_score(model, quant, use_case):
    pb = params_b(model)
    if pb < 1:
        base = 30
    elif pb < 3:
        base = 45
    elif pb < 7:
        base = 60
    elif pb < 10:
        base = 75
    elif pb < 20:
        base = 82
    elif pb < 40:
        base = 89
    else:
        base = 95

    name_lower = model.get("name", "").lower()
    if "qwen" in name_lower:
        base += 2
    if "deepseek" in name_lower:
        base += 3
    if "llama" in name_lower:
        base += 2
    if "mistral" in name_lower or "mixtral" in name_lower:
        base += 1
    if "gemma" in name_lower:
        base += 1

    base += QUANT_QUALITY_PENALTY.get(quant, 0)

    model_uc = infer_use_case(model)
    if model_uc == "coding" and use_case == "coding":
        base += 6
    if model_uc == "reasoning" and use_case == "reasoning" and pb >= 13:
        base += 5
    if model_uc == "multimodal" and use_case == "multimodal":
        base += 6

    return max(0, min(100, base))


def _speed_score(tps, use_case):
    target = SPEED_TARGET.get(use_case, 40)
    return max(0, min(100, (tps / target) * 100))


def _fit_score(required, available):
    if required > available:
        return 0
    if available <= 0:
        return 0
    ratio = required / available
    if ratio <= 0.5:
        return 60 + (ratio / 0.5) * 40
    if ratio <= 0.8:
        return 100
    if ratio <= 0.9:
        return 70
    return 50


def _context_score(ctx, use_case):
    target = CONTEXT_TARGET.get(use_case, 4096)
    if ctx >= target:
        return 100
    if ctx >= target / 2:
        return 70
    return 30


def _try_quant_at(model, quant, ctx, gpu_vram, available_ram):
    """Try a specific quant at a given context. Returns (run_mode, quant, ctx, mem) or None."""
    mem = estimate_memory_gb(model, quant, ctx)
    if gpu_vram > 0 and mem <= gpu_vram:
        return "gpu", quant, ctx, mem
    if gpu_vram > 0 and mem <= available_ram:
        return "cpu_offload", quant, ctx, mem
    if gpu_vram <= 0 and mem <= available_ram:
        return "cpu_only", quant, ctx, mem
    # Try halving context
    cur_ctx = ctx // 2
    while cur_ctx >= 1024:
        mem = estimate_memory_gb(model, quant, cur_ctx)
        if gpu_vram > 0 and mem <= gpu_vram:
            return "gpu", quant, cur_ctx, mem
        if mem <= available_ram:
            return ("cpu_offload" if gpu_vram > 0 else "cpu_only"), quant, cur_ctx, mem
        cur_ctx //= 2
    return None


def _quant_bits(q):
    """Approximate bit-width of a quant label so GGUF quant tiers (Q4/Q8/…) can
    be matched against prequantized formats (AWQ 4, AWQ-8bit, FP8, GPTQ-4bit…).
    Returns 0 when unknown (caller treats unknown as "don't filter")."""
    qu = (q or "").upper().replace("-", "").replace("_", "").replace(" ", "")
    # GGUF k-quants + float formats
    if qu.startswith("Q8") or "FP8" in qu:
        return 8
    if qu.startswith("Q4") or qu.startswith("IQ4"):
        return 4
    if qu.startswith("Q2") or qu.startswith("IQ2"):
        return 2
    if qu.startswith("Q3") or qu.startswith("IQ3"):
        return 3
    if qu.startswith("Q5"):
        return 5
    if qu.startswith("Q6"):
        return 6
    if qu.startswith("F16") or qu.startswith("BF16") or qu.startswith("F32"):
        return 16
    # Prequantized formats: pull the bit-width digit (AWQ4 / AWQ4BIT / GPTQ8 / 4BIT / INT8 …)
    m = re.search(r"(?:AWQ|GPTQ|MLX|EXL2|BNB|INT|W)(\d{1,2})", qu) or re.search(r"(\d{1,2})BIT", qu)
    if m:
        b = int(m.group(1))
        if 2 <= b <= 16:
            return b
    return 0


def analyze_model(model, system, target_quant=None):
    pb = params_b(model)
    if pb <= 0:
        return None

    use_case = infer_use_case(model)
    has_gpu = system.get("has_gpu", False)
    gpu_vram = (system.get("gpu_vram_gb") or 0) if has_gpu else 0
    gpu_count = system.get("gpu_count", 1) or 1
    single_gpu_vram = gpu_vram / gpu_count if gpu_count > 1 else gpu_vram
    available_ram = system.get("available_ram_gb", 0)
    # When the user has explicitly picked a GPU config (not RAM mode), they want
    # to see what runs ON the GPU(s) — not big models that only "fit" by spilling
    # most layers to system RAM. Zeroing the offload budget makes _try_quant_at
    # take only its GPU branches (fit on VRAM, shrinking context if needed),
    # otherwise return None. Fixes "96 GB GPU still lists a 175 GB model".
    gpu_only = bool(system.get("gpu_only")) and has_gpu and gpu_vram > 0
    eff_ram = 0 if gpu_only else available_ram
    is_moe = model.get("is_moe", False)
    ctx = model.get("context_length", 4096) or 4096

    native_quant = model.get("quantization", "Q4_K_M")
    preq = is_prequantized(model)

    # GGUF models can't be sharded across GPUs — use single GPU VRAM
    is_gguf = bool(model.get("gguf_sources"))
    quant_upper = (native_quant or "").upper()
    is_gguf_quant = any(quant_upper.startswith(p) for p in ("Q2", "Q3", "Q4", "Q5", "Q6", "Q8", "IQ", "F16", "F32"))
    # Single-GPU VRAM only applies to GGUF/dense builds (llama.cpp can't shard
    # across GPUs). Prequantized formats (AWQ/GPTQ/FP8) are served sharded by
    # vLLM across all GPUs, so they get the FULL multi-GPU VRAM — even when the
    # model also lists a GGUF alternate download (gguf_sources).
    if (is_gguf or is_gguf_quant) and not preq:
        effective_vram = single_gpu_vram
    else:
        effective_vram = gpu_vram

    # Determine which quant to evaluate at
    if preq:
        # AWQ/GPTQ/FP8/MLX come at a fixed bit-width. If the user picked a
        # specific quant tier (e.g. Q8 → 8-bit), only keep prequant models whose
        # native bit-width matches — otherwise selecting Q8 would still surface
        # AWQ-4bit models, mixing 4- and 8-bit in one view.
        if target_quant:
            _tb, _nb = _quant_bits(target_quant), _quant_bits(native_quant)
            if _tb and _nb and _tb != _nb:
                return None
        quant_to_try = native_quant
    elif target_quant:
        # User picked a specific quant
        quant_to_try = target_quant
    else:
        # Default: Q4_K_M (user's stated preference)
        quant_to_try = "Q4_K_M"

    result = _try_quant_at(model, quant_to_try, ctx, effective_vram, eff_ram)

    # If target quant doesn't fit and it's not pre-quantized, try lower quants
    if result is None and not preq and target_quant:
        from services.hwfit.models import QUANT_HIERARCHY
        idx = QUANT_HIERARCHY.index(target_quant) if target_quant in QUANT_HIERARCHY else -1
        for q in QUANT_HIERARCHY[idx + 1:]:
            result = _try_quant_at(model, q, ctx, effective_vram, eff_ram)
            if result:
                break

    if result is None:
        # Model doesn't fit on the user's current hardware. Surface it
        # anyway with a "too_tight" badge instead of silently dropping
        # it — without this, editing the hardware config to try LARGER
        # tiers never revealed the bigger models, because they were
        # filtered out before the user could see what would fit. The
        # client already knows how to render too_tight (red row).
        oversized_required = estimate_memory_gb(model, quant_to_try, ctx)
        return {
            "name": model.get("name"),
            "provider": model.get("provider"),
            "parameter_count": model.get("parameter_count"),
            "params_b": round(pb, 1),
            "is_moe": is_moe,
            "use_case": use_case,
            "fit_level": "too_tight",
            "run_mode": "no_fit",
            "quant": quant_to_try,
            "context": ctx,
            "required_gb": round(oversized_required, 1),
            "speed_tps": 0,
            "score": 0,
            "scores": {"quality": 0, "speed": 0, "fit": 0, "context": 0},
            "gguf_sources": model.get("gguf_sources", []),
            "context_length": model.get("context_length", 4096),
        }

    run_mode, quant, fit_ctx, required_gb = result

    # Determine fit level
    budget = effective_vram if run_mode == "gpu" else available_ram
    if required_gb > budget:
        return None
    if run_mode == "gpu":
        rec = model.get("recommended_ram_gb") or required_gb
        if rec <= gpu_vram:
            fit_level = "perfect"
        elif gpu_vram >= required_gb * 1.2:
            fit_level = "good"
        else:
            fit_level = "marginal"
    elif run_mode == "cpu_offload":
        fit_level = "good" if available_ram >= required_gb * 1.2 else "marginal"
    else:
        fit_level = "marginal"

    tps = _estimate_speed(model, quant, run_mode, system)

    q_score = _quality_score(model, quant, use_case)
    s_score = _speed_score(tps, use_case)
    f_score = _fit_score(required_gb, budget)
    c_score = _context_score(fit_ctx, use_case)

    wq, ws, wf, wc = USE_CASE_WEIGHTS.get(use_case, (0.45, 0.30, 0.15, 0.10))
    composite = q_score * wq + s_score * ws + f_score * wf + c_score * wc

    return {
        "name": model.get("name"),
        "provider": model.get("provider"),
        "parameter_count": model.get("parameter_count"),
        "params_b": round(pb, 1),
        "is_moe": is_moe,
        "use_case": use_case,
        "fit_level": fit_level,
        "run_mode": run_mode,
        "quant": quant,
        "context": fit_ctx,
        "required_gb": round(required_gb, 1),
        "speed_tps": round(tps, 1),
        "score": round(composite, 1),
        "scores": {
            "quality": round(q_score, 1),
            "speed": round(s_score, 1),
            "fit": round(f_score, 1),
            "context": round(c_score, 1),
        },
        "gguf_sources": model.get("gguf_sources", []),
        "context_length": model.get("context_length", 4096),
    }


SORT_KEYS = {
    "score": lambda r: r["score"],
    "speed": lambda r: r["speed_tps"],
    "vram": lambda r: r["required_gb"],
    "params": lambda r: r["params_b"],
    "context": lambda r: r["context"],
}


def rank_models(system, use_case=None, limit=50, search=None, sort="score", quant=None):
    """Rank all models against detected hardware. Returns sorted list of fit results."""
    models = get_models()
    results = []

    # Include image gen models only when explicitly filtered
    if use_case == "image_gen":
        try:
            from services.hwfit.image_models import rank_image_models
        except ImportError:
            rank_image_models = None
        if rank_image_models:
            img_results = rank_image_models(system, search=search)
        else:
            img_results = []
        for im in img_results:
            fit_map = {"perfect": "perfect", "good": "good", "tight": "marginal", "no_fit": "too_tight", "no_gpu": "too_tight"}
            results.append({
                "name": im["id"],
                "provider": im["provider"],
                "parameter_count": f"{im['params_b']}B",
                "params_b": im["params_b"],
                "is_moe": False,
                "use_case": "image_gen",
                "fit_level": fit_map.get(im["fit"], "too_tight"),
                "run_mode": "gpu" if im["fits"] else "no_fit",
                "quant": im.get("quant", "BF16"),
                "context": 0,
                "context_length": 0,
                "required_gb": round(im.get("vram_needed") or 0, 1),
                "speed_tps": 0,
                "score": float(im["score"]),
                "scores": {"quality": float(im["quality"]), "speed": float(im["speed"]), "fit": 0, "context": 0},
                "gguf_sources": [],
                "is_image_gen": True,
                "capabilities": im.get("capabilities", []),
                "description": im.get("description", ""),
            })
        if use_case == "image_gen":
            sort_fn = SORT_KEYS.get(sort, SORT_KEYS["score"])
            results.sort(key=sort_fn, reverse=(sort != "vram"))
            return results[:limit]

    # If user picked a prequantized format (AWQ/FP8/GPTQ), filter to only those models
    filter_native = quant and any(quant.startswith(p) for p in ("AWQ-", "GPTQ-", "FP8"))

    # MLX-quantized models only run on Apple Silicon (Metal). Exclude them on
    # every other backend (CUDA / ROCm / CPU) so Linux/Windows users don't see
    # unrunnable suggestions.
    system_backend = (system.get("backend") or "").lower()
    apple_silicon = system_backend in ("mps", "metal", "apple")

    for m in models:
        native_q = m.get("quantization", "")

        # Drop MLX models on non-Apple hardware
        if not apple_silicon and native_q.startswith("mlx-"):
            continue

        # Format filter: AWQ tab → only AWQ models, FP8 tab → only FP8 models
        if filter_native:
            if quant == "FP8" and native_q != "FP8":
                continue
            if quant.startswith("AWQ") and not native_q.startswith("AWQ"):
                continue
            if quant.startswith("GPTQ") and not native_q.startswith("GPTQ"):
                continue

        if search:
            name = m.get("name", "").lower()
            provider = m.get("provider", "").lower()
            if search.lower() not in name and search.lower() not in provider:
                continue

        result = analyze_model(m, system, target_quant=quant)
        if result is None:
            continue

        if use_case:
            model_uc = infer_use_case(m)
            if use_case != model_uc and use_case != "general":
                continue

        results.append(result)

    # Pick the visible SET by best fit (score) first, so it stays the same no
    # matter which column the user sorts by — otherwise sorting by params would
    # truncate to the N biggest models (huge ones that don't even fit) while
    # sorting by vram showed the N smallest. Only AFTER choosing the set do we
    # order it by the requested column.
    results.sort(key=SORT_KEYS["score"], reverse=True)
    results = results[:limit]
    sort_fn = SORT_KEYS.get(sort, SORT_KEYS["score"])
    # vram ascending (smallest first), everything else descending (biggest first)
    results.sort(key=sort_fn, reverse=(sort != "vram"))
    return results