"""Provider payload helpers for translating ``RunConfig.model_params``."""

from __future__ import annotations

import json
from typing import Any

from llm_connect._diagnostics import (
    diagnostics_enabled,
    json_safe,
    record_adapter_transformation,
)


# OpenAI Chat Completions fields that map straight through from model_params.
# Anything not in this set is provider-specific and must be either translated
# or dropped. Blind merges are deliberately avoided because OpenAI-compatible
# providers commonly reject unknown top-level fields with HTTP 400.
OPENAI_CHAT_PASSTHROUGH_FIELDS = frozenset(
    {
        "top_p",
        "n",
        "stream",
        "stop",
        "presence_penalty",
        "frequency_penalty",
        "logit_bias",
        "user",
        "seed",
        "tools",
        "tool_choice",
        "response_format",
        "logprobs",
        "top_logprobs",
        "parallel_tool_calls",
    }
)


DROPPED_NON_OPENAI_FIELDS = frozenset(
    {
        "reasoning_effort",
        "max_depth",
        "claude_cli_path",
        "json_schema",
    }
)


GEMINI_TOP_LEVEL_FIELDS = frozenset(
    {
        "safetySettings",
        "tools",
        "toolConfig",
        "systemInstruction",
        "cachedContent",
    }
)


GEMINI_GENERATION_CONFIG_FIELDS = frozenset(
    {
        "candidateCount",
        "stopSequences",
        "maxOutputTokens",
        "temperature",
        "topP",
        "topK",
        "responseMimeType",
        "responseSchema",
    }
)


GEMINI_GENERATION_CONFIG_ALIASES = {
    "candidate_count": "candidateCount",
    "stop_sequences": "stopSequences",
    "max_output_tokens": "maxOutputTokens",
    "top_p": "topP",
    "top_k": "topK",
    "response_mime_type": "responseMimeType",
    "response_schema": "responseSchema",
}


def merge_openai_chat_model_params(payload: dict[str, Any], model_params: dict[str, Any]) -> None:
    """Merge model_params into an OpenAI Chat Completions-style payload.

    Translates ``json_schema`` to ``response_format``, passes known OpenAI
    fields through, and drops Claude/llm-connect-only knobs.
    """

    before = json_safe(payload) if diagnostics_enabled() else None

    schema = _coerce_json_schema(model_params.get("json_schema"))
    caller_response_format = model_params.get("response_format")
    if schema is not None and caller_response_format is None and "response_format" not in payload:
        payload["response_format"] = {
            "type": "json_schema",
            "json_schema": {
                "name": "structured_output",
                "schema": schema,
                "strict": False,
            },
        }

    for key, value in model_params.items():
        if key in DROPPED_NON_OPENAI_FIELDS:
            continue
        if key in OPENAI_CHAT_PASSTHROUGH_FIELDS:
            payload[key] = value

    if before is not None:
        record_adapter_transformation("merge_model_params.openai_chat", before, payload)


def merge_gemini_model_params(payload: dict[str, Any], model_params: dict[str, Any]) -> None:
    """Merge model_params into a Gemini ``generateContent`` payload."""

    before = json_safe(payload) if diagnostics_enabled() else None
    generation_config = payload.setdefault("generationConfig", {})

    schema = _coerce_json_schema(model_params.get("json_schema"))
    if schema is not None and "responseSchema" not in generation_config:
        generation_config["responseMimeType"] = "application/json"
        generation_config["responseSchema"] = schema

    explicit_generation_config = model_params.get("generationConfig")
    if isinstance(explicit_generation_config, dict):
        generation_config.update(explicit_generation_config)

    for key, value in model_params.items():
        if key in {"json_schema", "generationConfig", "reasoning_effort", "max_depth"}:
            continue
        if key in GEMINI_TOP_LEVEL_FIELDS:
            payload[key] = value
            continue
        gemini_key = GEMINI_GENERATION_CONFIG_ALIASES.get(key, key)
        if gemini_key in GEMINI_GENERATION_CONFIG_FIELDS:
            generation_config[gemini_key] = value

    if before is not None:
        record_adapter_transformation("merge_model_params.gemini", before, payload)


def _coerce_json_schema(schema: Any) -> dict[str, Any] | None:
    if isinstance(schema, str):
        try:
            schema = json.loads(schema)
        except (TypeError, ValueError):
            return None
    if isinstance(schema, dict):
        return schema
    return None