#!/usr/bin/env python3
"""
LLM-Powered Entity Extractor — Uses Ollama for Named Entity Recognition.

Standalone module. No pip dependencies beyond stdlib.
Calls Ollama HTTP API with structured NER prompts.

Configuration via environment variables:
    DARKPLEX_OLLAMA_URL      — Ollama base URL (default: http://localhost:11434)
    DARKPLEX_OLLAMA_MODEL    — Model name (default: mistral:7b)
    DARKPLEX_OLLAMA_TIMEOUT  — Timeout in seconds (default: 10)
    DARKPLEX_EXTRACTOR       — llm|regex|auto (default: auto)
"""

import json
import logging
import os
import urllib.request
import urllib.error

log = logging.getLogger("llm-extractor")

OLLAMA_URL = os.environ.get("DARKPLEX_OLLAMA_URL", "http://localhost:11434")
OLLAMA_MODEL = os.environ.get("DARKPLEX_OLLAMA_MODEL", "mistral:7b")
OLLAMA_TIMEOUT = int(os.environ.get("DARKPLEX_OLLAMA_TIMEOUT", "30"))

VALID_TYPES = {"person", "organization", "company", "project", "technology",
               "location", "event", "concept", "product"}

NER_PROMPT = """Extract all named entities from the text below. Return ONLY a JSON object.
Each key is the entity name (lowercase), each value has "type" and "context".

Valid types: person, organization, company, project, technology, location, event, concept, product

Rules:
- Skip common/generic words (the, system, message, etc.)
- Entity names should be lowercase, use hyphens for multi-word
- "context" is a 2-5 word description of the entity's role in the text
- If no entities found, return empty JSON object
- Return ONLY valid JSON, no explanation

Text:
{text}

JSON:"""

BATCH_PROMPT = """Extract all named entities from these texts. Return ONLY a JSON object.
Each key is the entity name (lowercase, hyphens for spaces), each value has "type" and "context".

Valid types: person, organization, company, project, technology, location, event, concept, product

Rules:
- Skip common/generic words
- "context" is a 2-5 word description
- If no entities found, return empty JSON object
- Return ONLY valid JSON, no markdown, no explanation

Texts:
{texts}

JSON:"""


def _call_ollama(prompt: str) -> str | None:
    """Call Ollama generate API. Returns response text or None on failure."""
    payload = json.dumps({
        "model": OLLAMA_MODEL,
        "prompt": prompt,
        "stream": False,
        "options": {"temperature": 0.1, "num_predict": 1024},
    }).encode()

    req = urllib.request.Request(
        f"{OLLAMA_URL}/api/generate",
        data=payload,
        headers={"Content-Type": "application/json"},
        method="POST",
    )

    try:
        with urllib.request.urlopen(req, timeout=OLLAMA_TIMEOUT) as resp:
            data = json.loads(resp.read().decode())
            return data.get("response", "")
    except (urllib.error.URLError, TimeoutError, OSError) as e:
        log.warning(f"Ollama call failed: {e}")
        return None
    except Exception as e:
        log.warning(f"Ollama unexpected error: {e}")
        return None


def _parse_json_response(text: str) -> dict:
    """Extract JSON dict from LLM response, handling markdown fences etc."""
    if not text:
        return {}
    # Strip markdown code fences
    text = text.strip()
    if text.startswith("```"):
        lines = text.split("\n")
        lines = [l for l in lines if not l.strip().startswith("```")]
        text = "\n".join(lines)

    # Find the JSON object
    start = text.find("{")
    if start == -1:
        return {}

    # Find matching closing brace
    depth = 0
    for i in range(start, len(text)):
        if text[i] == "{":
            depth += 1
        elif text[i] == "}":
            depth -= 1
            if depth == 0:
                try:
                    return json.loads(text[start:i + 1])
                except json.JSONDecodeError:
                    return {}
    return {}


def _normalize_entities(raw: dict) -> dict:
    """Normalize and validate extracted entities."""
    result = {}
    for name, info in raw.items():
        if not isinstance(info, dict):
            continue
        name = name.strip().lower().replace("_", "-").replace(" ", "-")
        if len(name) < 2 or len(name) > 80:
            continue

        etype = info.get("type", "unknown").lower().strip()
        if etype not in VALID_TYPES:
            # Map common aliases
            aliases = {"org": "organization", "tech": "technology", "loc": "location",
                       "place": "location", "tool": "technology", "framework": "technology",
                       "language": "technology", "app": "product", "software": "product",
                       "service": "product", "group": "organization", "team": "organization"}
            etype = aliases.get(etype, "concept")

        context = info.get("context", "")
        if isinstance(context, str):
            context = context[:100]
        else:
            context = ""

        result[name] = {"type": etype, "context": context, "match": "llm"}

    return result


def extract_entities_llm(text: str) -> dict[str, dict] | None:
    """
    Extract entities from text using Ollama LLM.

    Returns dict of {name: {type, context, match}} or None if LLM unavailable.
    None signals caller to fall back to regex.
    """
    if not text or len(text) < 10:
        return {}

    # Truncate very long texts
    if len(text) > 2000:
        text = text[:2000]

    prompt = NER_PROMPT.format(text=text)
    response = _call_ollama(prompt)
    if response is None:
        return None  # Signal fallback

    raw = _parse_json_response(response)
    return _normalize_entities(raw)


def extract_entities_llm_batch(texts: list[str]) -> dict[str, dict] | None:
    """
    Extract entities from multiple texts in one LLM call.

    Returns combined dict or None if LLM unavailable.
    """
    if not texts:
        return {}

    # Filter and truncate
    clean = []
    for t in texts:
        if t and len(t) >= 10:
            clean.append(t[:500] if len(t) > 500 else t)
    if not clean:
        return {}

    # Limit batch size to keep prompt reasonable
    if len(clean) > 10:
        clean = clean[:10]

    numbered = "\n".join(f"[{i+1}] {t}" for i, t in enumerate(clean))
    prompt = BATCH_PROMPT.format(texts=numbered)
    response = _call_ollama(prompt)
    if response is None:
        return None

    raw = _parse_json_response(response)
    return _normalize_entities(raw)


def is_available() -> bool:
    """Check if Ollama is reachable."""
    try:
        req = urllib.request.Request(f"{OLLAMA_URL}/api/tags", method="GET")
        with urllib.request.urlopen(req, timeout=3) as resp:
            return resp.status == 200
    except Exception:
        return False