# retoor <retoor@molodetz.nl>

import logging
import re
from datetime import datetime
from typing import Any, Optional

logger = logging.getLogger(__name__)

DATE_LABEL = "Current date"

_MONTH_NAMES = (
    "january|february|march|april|may|june|july|august|september|october|"
    "november|december|jan|feb|mar|apr|jun|jul|aug|sep|sept|oct|nov|dec"
)

_DATE_PATTERNS: tuple[re.Pattern[str], ...] = (
    re.compile(r"\b\d{4}-\d{1,2}-\d{1,2}\b"),
    re.compile(r"\b\d{1,2}/\d{1,2}/\d{4}\b"),
    re.compile(r"\b\d{1,2}-\d{1,2}-\d{4}\b"),
    re.compile(r"\b\d{1,2}\.\d{1,2}\.\d{4}\b"),
    re.compile(
        rf"\b\d{{1,2}}\s+(?:{_MONTH_NAMES})\.?\s+\d{{4}}\b",
        re.IGNORECASE,
    ),
    re.compile(
        rf"\b(?:{_MONTH_NAMES})\.?\s+\d{{1,2}}(?:st|nd|rd|th)?,?\s+\d{{4}}\b",
        re.IGNORECASE,
    ),
)


def contains_date(text: str) -> bool:
    return any(pattern.search(text) for pattern in _DATE_PATTERNS)


def current_date_eu() -> str:
    return datetime.now().strftime("%d/%m/%Y")


def system_message_text(content: Any) -> str:
    if isinstance(content, str):
        return content
    if isinstance(content, list):
        parts: list[str] = []
        for block in content:
            if isinstance(block, dict) and block.get("type") == "text":
                value = block.get("text")
                if isinstance(value, str):
                    parts.append(value)
        return "\n".join(parts)
    return ""


def compose_system_content(
    preamble: str, client_content: Any, date_eu: str
) -> str:
    preamble_text = (preamble or "").strip()
    client_text = system_message_text(client_content)
    sections: list[str] = []
    if preamble_text:
        sections.append(preamble_text)
    combined_for_date = f"{preamble_text}\n{client_text}"
    if not contains_date(combined_for_date):
        sections.append(f"{DATE_LABEL}: {date_eu}")
    if client_text:
        sections.append(client_text)
    return "\n\n".join(sections)


def apply_system_directives(
    messages: list, preamble: str, date_eu: Optional[str] = None
) -> list:
    date_value = date_eu or current_date_eu()
    preamble_text = (preamble or "").strip()
    result: list = list(messages)
    system_index = next(
        (
            index
            for index, message in enumerate(result)
            if isinstance(message, dict) and message.get("role") == "system"
        ),
        None,
    )
    if system_index is not None:
        original = result[system_index]
        composed = compose_system_content(
            preamble_text, original.get("content"), date_value
        )
        updated = dict(original)
        updated["content"] = composed
        result[system_index] = updated
        logger.debug(
            "Gateway composed existing system message (preamble=%s, date=%s)",
            bool(preamble_text),
            date_value,
        )
        return result
    if not preamble_text:
        return result
    composed = compose_system_content(preamble_text, "", date_value)
    if not composed.strip():
        return result
    result.insert(0, {"role": "system", "content": composed})
    logger.info(
        "Gateway injected a system message (preamble=%s, date=%s)",
        bool(preamble_text),
        date_value,
    )
    return result