"""Provider adapter for verified delivery; guards stay independent of the model vendor."""

from __future__ import annotations

import json
import os
import urllib.parse
import urllib.request


class NoRedirect(urllib.request.HTTPRedirectHandler):
    def redirect_request(self, req, fp, code, msg, headers, newurl):
        return None


def complete_with_configured_model(messages: list[dict], *, max_tokens: int | None = None) -> dict:
    if max_tokens is not None and (type(max_tokens) is not int or not 1 <= max_tokens <= 16384):
        raise ValueError("Invalid model output budget")
    provider = os.getenv("ANSWER_PROVIDER", "openai_compatible").strip()
    model = os.getenv("ANSWER_MODEL", "").strip()
    if provider == "anthropic":
        key = (os.getenv("ANSWER_API_KEY") or os.getenv("ANTHROPIC_API_KEY", "")).strip()
        endpoint = os.getenv("ANSWER_LLM_URL", "https://api.anthropic.com/v1/messages").strip()
        system = "\n\n".join(row["content"] for row in messages if row["role"] == "system")
        body = {
            "model": model,
            "messages": [row for row in messages if row["role"] != "system"],
            "max_tokens": max_tokens or int(os.getenv("ANSWER_MAX_TOKENS", "4096")),
            "temperature": 0,
        }
        if system:
            body["system"] = system
        headers = {"x-api-key": key, "anthropic-version": "2023-06-01"}
    elif provider == "openai_compatible":
        # Compatibility for historical experiments; new installations use ANSWER_API_KEY.
        legacy = os.getenv("OPENWEBUI_API_KEY", "").strip()
        key = os.getenv("ANSWER_API_KEY", "").strip() or legacy
        endpoint = os.getenv(
            "ANSWER_LLM_URL", "https://ui.tukekemt.xyz/api/chat/completions" if legacy else ""
        ).strip()
        model = model or ("model120-fast" if legacy else "")
        body = {"model": model, "messages": messages, "temperature": 0, "stream": False}
        if max_tokens is not None:
            body["max_tokens"] = max_tokens
        headers = {"Authorization": "Bearer " + key}
    else:
        raise RuntimeError("Unsupported answer provider")
    parsed = urllib.parse.urlsplit(endpoint)
    if (
        not key
        or not model
        or any(c in key for c in "\r\n")
        or parsed.scheme != "https"
        or not parsed.hostname
        or parsed.username is not None
        or parsed.password is not None
        or parsed.fragment
        or parsed.query
        or any(c.isspace() for c in endpoint)
    ):
        raise RuntimeError("Answer model is not configured")
    request = urllib.request.Request(
        endpoint,
        data=json.dumps(body, ensure_ascii=False).encode(),
        headers={"Content-Type": "application/json", **headers},
    )
    with urllib.request.build_opener(NoRedirect()).open(request, timeout=120) as response:
        data = response.read(2 * 1024 * 1024 + 1)
    if len(data) > 2 * 1024 * 1024:
        raise RuntimeError("Answer model output is too large")
    value = json.loads(data)
    if provider == "anthropic":
        if value.get("stop_reason") != "end_turn":
            raise RuntimeError("Incomplete answer model output")
        text = "".join(
            block["text"] for block in value.get("content", []) if block.get("type") == "text"
        )
        if not text:
            raise RuntimeError("Missing answer model output")
        return {"choices": [{"message": {"content": text}}]}
    return value