"""User overrides + custom catalog entries, persisted on the package's main volume.

File: /data/models-overrides.yaml (only when something has been customized).
Survives package updates because /data is the StartOS volume.

Shape:
    knobs:
      qwen36:
        max_model_len: 65536
        gpu_memory_utilization: 0.85
        fastsafetensors: true
        prefix_caching: true
        kv_cache_dtype: fp8     # one of: 'fp8' | 'auto' | null
    custom:
      - key: my-new-model
        display_name: My New Model (from download)
        repo: my-org/my-model
        size_gb: 20
        mode: solo
        description: null
        capabilities: []
        knobs:
          max_model_len: 32768
          gpu_memory_utilization: 0.85
          fastsafetensors: true
          prefix_caching: true
          kv_cache_dtype: fp8
"""
from __future__ import annotations
import os
from pathlib import Path
from typing import Any, Optional
import yaml


KNOWN_FLAG_MAP = {
    "max_model_len": "--max-model-len",
    "gpu_memory_utilization": "--gpu-memory-utilization",
}


def _path() -> str:
    # Container: /data/models-overrides.yaml. Local dev: cwd or env override.
    return os.environ.get("MODELS_OVERRIDES", "/data/models-overrides.yaml")


def load_overrides() -> dict:
    p = _path()
    try:
        with open(p) as f:
            data = yaml.safe_load(f) or {}
    except FileNotFoundError:
        return {"knobs": {}, "custom": []}
    data.setdefault("knobs", {})
    data.setdefault("custom", [])
    return data


def save_overrides(data: dict) -> None:
    p = _path()
    parent = Path(p).parent
    parent.mkdir(parents=True, exist_ok=True)
    with open(p, "w") as f:
        yaml.safe_dump(data, f, sort_keys=False)


def set_knobs(key: str, knobs: dict) -> dict:
    data = load_overrides()
    if not knobs:
        data["knobs"].pop(key, None)
    else:
        data["knobs"][key] = knobs
    save_overrides(data)
    return data


def add_custom(entry: dict) -> dict:
    data = load_overrides()
    # Replace if same key already exists
    data["custom"] = [c for c in data["custom"] if c.get("key") != entry["key"]]
    data["custom"].append(entry)
    save_overrides(data)
    return data


def delete_custom(key: str) -> dict:
    data = load_overrides()
    data["custom"] = [c for c in data["custom"] if c.get("key") != key]
    data["knobs"].pop(key, None)
    save_overrides(data)
    return data


def apply_knobs_to_args(vllm_args: list[str], knobs: Optional[dict]) -> list[str]:
    """Return a new vllm_args list with knob values overriding matching flags."""
    if not knobs:
        return list(vllm_args)
    skip_prefixes: list[str] = []
    for k, flag in KNOWN_FLAG_MAP.items():
        if k in knobs:
            skip_prefixes.append(f"{flag}=")
            skip_prefixes.append(flag + " ")  # rare style
    # opt-in flag toggles
    if "fastsafetensors" in knobs:
        skip_prefixes.append("--load-format=")
    if "prefix_caching" in knobs:
        skip_prefixes.append("--enable-prefix-caching")
    if "kv_cache_dtype" in knobs:
        skip_prefixes.append("--kv-cache-dtype=")

    filtered = [a for a in vllm_args if not any(a.startswith(p) or a == p.rstrip("= ") for p in skip_prefixes)]

    for k, flag in KNOWN_FLAG_MAP.items():
        if k in knobs and knobs[k] is not None:
            filtered.append(f"{flag}={knobs[k]}")

    if knobs.get("fastsafetensors"):
        filtered.append("--load-format=fastsafetensors")
    if knobs.get("prefix_caching"):
        filtered.append("--enable-prefix-caching")
    kvd = knobs.get("kv_cache_dtype")
    if kvd and kvd != "auto":
        filtered.append(f"--kv-cache-dtype={kvd}")

    return filtered


def extract_knobs_from_args(vllm_args: list[str]) -> dict:
    """Reverse: read default knob values from a model's bundled vllm_args, so the UI
    has a starting point even before the user has saved any overrides."""
    knobs: dict[str, Any] = {}
    for a in vllm_args:
        if a.startswith("--max-model-len="):
            try: knobs["max_model_len"] = int(a.split("=", 1)[1])
            except ValueError: pass
        elif a.startswith("--gpu-memory-utilization="):
            try: knobs["gpu_memory_utilization"] = float(a.split("=", 1)[1])
            except ValueError: pass
        elif a == "--load-format=fastsafetensors":
            knobs["fastsafetensors"] = True
        elif a == "--enable-prefix-caching":
            knobs["prefix_caching"] = True
        elif a.startswith("--kv-cache-dtype="):
            knobs["kv_cache_dtype"] = a.split("=", 1)[1]
    return knobs