from __future__ import annotations

from decimal import Decimal
from typing import Any

from app.discovery.enums import DiffStatus, LifecycleStatus, RunStatus


RELEVANT_ATTR_IGNORE = {"title", "html", "presentation", "raw_title"}


def observations_changed(previous: dict[str, Any] | None, current: dict[str, Any] | None) -> bool:
    if previous is None or current is None:
        return previous != current
    if _money(previous.get("best_price")) != _money(current.get("best_price")):
        return True
    if previous.get("availability") != current.get("availability"):
        return True
    if previous.get("seller_count") != current.get("seller_count"):
        return True
    prev_attrs = _technical(previous.get("normalized_attributes") or {})
    curr_attrs = _technical(current.get("normalized_attributes") or {})
    return prev_attrs != curr_attrs


def _money(value: Any) -> Decimal | None:
    if value is None:
        return None
    return Decimal(str(value))


def _technical(attrs: dict[str, Any]) -> dict[str, Any]:
    return {key: attrs[key] for key in sorted(attrs) if key not in RELEVANT_ATTR_IGNORE}


def diff_run(
    *,
    previous_ids: set[Any],
    current_ids: set[Any],
    previous_obs: dict[Any, dict[str, Any]],
    current_obs: dict[Any, dict[str, Any]],
    run_status: str,
) -> dict[Any, DiffStatus]:
    result: dict[Any, DiffStatus] = {}
    for ref_id in current_ids:
        if ref_id not in previous_ids:
            result[ref_id] = DiffStatus.NEW
        elif observations_changed(previous_obs.get(ref_id), current_obs.get(ref_id)):
            result[ref_id] = DiffStatus.CHANGED
        else:
            result[ref_id] = DiffStatus.UNCHANGED
    if run_status == RunStatus.SUCCESS.value:
        for ref_id in previous_ids - current_ids:
            result[ref_id] = DiffStatus.MISSING
    return result


def next_lifecycle(
    *,
    current: str,
    missing_in_success_run: bool,
    consecutive_missing: int,
    reappeared: bool,
) -> tuple[str, int]:
    if current == LifecycleStatus.ARCHIVED.value:
        return current, consecutive_missing
    if reappeared:
        return LifecycleStatus.ACTIVE.value, 0
    if missing_in_success_run:
        streak = consecutive_missing + 1
        if streak >= 3:
            return LifecycleStatus.DISAPPEARED.value, streak
        return LifecycleStatus.ACTIVE.value, streak
    return current, consecutive_missing