"""Optional local JSON parser for non-JSON upstream responses.

The parser talks to any OpenAI-compatible chat-completions endpoint, for
example Ollama at ``http://127.0.0.1:11434/v1``. It is opt-in: set
``LOCAL_PARSER_URL`` and ``LOCAL_PARSER_MODEL`` and non-JSON external results
are sent to the local model and converted to JSON.

The parser is a converter, not a second analyst. Its prompt tells the model to
preserve the source facts and never invent prices, targets, or recommendations.
If parsing fails, the app keeps the raw response and returns a clear error.
"""

from __future__ import annotations

import json
import os
from typing import Any

import requests

DEFAULT_MODEL = "llama3.1"
DEFAULT_TIMEOUT_SECONDS = 90.0
MAX_INPUT_CHARS = 12000
MAX_OUTPUT_TOKENS = 1600

SYSTEM_PROMPT = (
    "You convert raw stock-analysis output into strict JSON. "
    "Return only one JSON object. Do not use markdown or code fences. "
    "Preserve the source facts exactly. Do not invent prices, targets, "
    "ratings, or recommendations. If a field is missing, leave it out."
)

_settings: dict[str, Any] = {
    "url": "",
    "model": DEFAULT_MODEL,
    "timeout": DEFAULT_TIMEOUT_SECONDS,
}


class LocalParserError(RuntimeError):
    """Raised when the local model cannot produce valid JSON."""


def configure(
    *,
    url: str | None = None,
    model: str | None = None,
    timeout: float | None = None,
) -> dict[str, Any]:
    """Apply settings from ``app.py``. All values are optional."""
    if url is not None:
        _settings["url"] = str(url).strip()
    if model is not None:
        _settings["model"] = str(model).strip()
    if timeout is not None:
        _settings["timeout"] = float(timeout)
    return settings()


def settings() -> dict[str, Any]:
    """Return a copy of the current settings, without any credentials."""
    return {
        "configured": is_configured(),
        "model": _resolved_model(),
        "timeout": float(_settings["timeout"]),
    }


def is_configured() -> bool:
    return bool(_resolved_url()) and bool(_resolved_model())


def model_name() -> str:
    return _resolved_model()


def _resolved_url() -> str:
    return str(_settings["url"] or os.getenv("LOCAL_PARSER_URL", "")).strip()


def _resolved_model() -> str:
    return str(_settings["model"] or os.getenv("LOCAL_PARSER_MODEL", DEFAULT_MODEL)).strip()


def _chat_url(base: str) -> str:
    url = base.rstrip("/")
    if url.endswith("/chat/completions"):
        return url
    if url.endswith("/v1"):
        return f"{url}/chat/completions"
    return f"{url}/v1/chat/completions"


def _extract_json(text: str) -> Any:
    candidate = text.strip()
    if candidate.startswith("```"):
        lines = candidate.splitlines()
        if lines and lines[0].startswith("```"):
            lines = lines[1:]
        if lines and lines[-1].strip().startswith("```"):
            lines = lines[:-1]
        candidate = "\n".join(lines).strip()

    try:
        return json.loads(candidate)
    except ValueError:
        pass

    starts = [index for index in (candidate.find("{"), candidate.find("[")) if index != -1]
    if not starts:
        raise ValueError("no JSON value found")
    start = min(starts)

    ends = [candidate.rfind(char) for char in ("}", "]")]
    ends = [index for index in ends if index != -1]
    if not ends:
        raise ValueError("no JSON value end found")
    end = max(ends)
    if end <= start:
        raise ValueError("invalid JSON span")

    return json.loads(candidate[start : end + 1])


def parse_json(raw_text: str, ticker: str = "") -> Any:
    """Convert raw upstream text into JSON using the configured local model."""
    if not is_configured():
        raise LocalParserError("The local parser is not configured.")
    if not raw_text.strip():
        raise LocalParserError("The upstream response was empty.")

    model = _resolved_model()
    user_content = (
        f"Ticker: {ticker or 'unknown'}\n\n"
        "Raw analysis output:\n"
        f"{raw_text[:MAX_INPUT_CHARS]}"
    )
    payload = {
        "model": model,
        "messages": [
            {"role": "system", "content": SYSTEM_PROMPT},
            {"role": "user", "content": user_content},
        ],
        "temperature": 0,
        "max_tokens": MAX_OUTPUT_TOKENS,
        "stream": False,
    }

    try:
        response = requests.post(
            _chat_url(_resolved_url()),
            json=payload,
            timeout=float(_settings["timeout"]),
        )
    except requests.RequestException as exc:
        raise LocalParserError(
            f"Local parser request failed ({type(exc).__name__})."
        ) from exc

    if not response.ok:
        detail = (response.text or "").strip()[:200]
        raise LocalParserError(
            f"Local parser returned HTTP {response.status_code}: {detail}"
        )

    try:
        data = response.json()
    except ValueError as exc:
        raise LocalParserError("Local parser returned a non-JSON response.") from exc

    try:
        content = data["choices"][0]["message"]["content"]
    except (KeyError, IndexError, TypeError) as exc:
        raise LocalParserError(
            "Local parser response did not contain message content."
        ) from exc

    if not isinstance(content, str) or not content.strip():
        raise LocalParserError("Local parser returned empty content.")

    try:
        return _extract_json(content)
    except ValueError as exc:
        raise LocalParserError("Local parser output was not valid JSON.") from exc