"""Project model-facing timestamps after saving the original query evidence."""
from datetime import datetime, timedelta, timezone
import re
from typing import Any

DISPLAY_TIME_ZONE = "Asia/Shanghai"
DISPLAY_OFFSET = timezone(timedelta(hours=8))
_INSTANT = re.compile(
    r"\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}(?P<fraction>\.\d+)?(?:Z|[+-]\d{2}:\d{2})"
)
_PROSE_FIELDS = frozenset({
    "title", "summary", "detail", "description", "notice", "label", "message",
    "current_conclusion", "conclusion_boundary", "recommendations", "pending_items",
    "missing_data", "required_data", "impact", "scope", "fallback_text", "text",
})
_OPAQUE_FIELDS = frozenset({"id", "cursor", "url", "uri", "path", "sha256", "instructions", "code", "sql"})
_OPAQUE_SUFFIXES = ("_id", "_ids", "_ref", "_refs", "_cursor", "_digest", "_sha256", "_url", "_uri", "_path")


def _opaque(key: str) -> bool:
    return key in _OPAQUE_FIELDS or key.endswith(_OPAQUE_SUFFIXES)


def _display_instant(value: str) -> str:
    match = _INSTANT.fullmatch(value)
    if match is None:
        return value
    try:
        local = datetime.fromisoformat(value).astimezone(DISPLAY_OFFSET)
    except (ValueError, OverflowError):
        return value
    fraction = match.group("fraction") or ""
    return (f"{local.year:04d}-{local.month:02d}-{local.day:02d}T"
            f"{local.hour:02d}:{local.minute:02d}:{local.second:02d}{fraction}+08:00")


def display_time_text(value: str) -> str:
    """Convert explicit instants in prose while retaining links and quoted code."""
    parts = re.split(r"(https?://\S+|tjwater://\S+|`[^`]*`)", value)
    for index in range(0, len(parts), 2):
        parts[index] = re.sub(
            r"(?<![A-Za-z0-9_/+:.-])" + _INSTANT.pattern + r"(?![A-Za-z0-9_:+/-])",
            lambda match: _display_instant(match.group()), parts[index],
        )
    return "".join(parts)


def display_query_result(value: Any, *, field: str = "") -> Any:
    """Keep instants, fractions and identifiers intact; change display offsets."""
    if _opaque(field):
        return value
    if isinstance(value, dict):
        path = value.get("selected_path") or []
        opaque_selection = isinstance(path, list) and bool(path) and _opaque(str(path[-1]))
        return {key: item if key == "value" and opaque_selection else display_query_result(item, field=key)
                for key, item in value.items()}
    if isinstance(value, list):
        return [display_query_result(item, field=field) for item in value]
    if isinstance(value, str):
        if field in _PROSE_FIELDS:
            return display_time_text(value)
        return _display_instant(value) if len(value) <= 128 else value
    return value