"""Phase 7.4 Campaign Engine validators — lifecycle transitions, window, and grant math."""
from __future__ import annotations

import math
from datetime import date

from shared.exceptions import AppError

from app.models.types import CampaignStatus

# Canonical transitions for the Campaign Engine lifecycle actions.
ALLOWED_TRANSITIONS: dict[str, set[CampaignStatus]] = {
    "schedule": {CampaignStatus.DRAFT},
    "activate": {
        CampaignStatus.DRAFT,
        CampaignStatus.SCHEDULED,
        CampaignStatus.PAUSED,
    },
    "pause": {CampaignStatus.ACTIVE},
    "resume": {CampaignStatus.PAUSED},
    "expire": {
        CampaignStatus.ACTIVE,
        CampaignStatus.PAUSED,
        CampaignStatus.SCHEDULED,
    },
}

TARGET_STATUS: dict[str, CampaignStatus] = {
    "schedule": CampaignStatus.SCHEDULED,
    "activate": CampaignStatus.ACTIVE,
    "pause": CampaignStatus.PAUSED,
    "resume": CampaignStatus.ACTIVE,
    "expire": CampaignStatus.EXPIRED,
}


def ensure_campaign_transition(*, action: str, current: CampaignStatus) -> None:
    allowed = ALLOWED_TRANSITIONS.get(action, set())
    if current not in allowed:
        raise AppError(
            "انتقال وضعیت کمپین مجاز نیست",
            status_code=409,
            error_code="invalid_campaign_transition",
            details={
                "from_status": current.value,
                "action": action,
                "allowed_from": sorted(s.value for s in allowed),
            },
        )


def target_campaign_status(action: str) -> CampaignStatus:
    return TARGET_STATUS[action]


def ensure_schedule_requires_start_date(starts_on: date | None) -> None:
    if starts_on is None:
        raise AppError(
            "برای زمان‌بندی کمپین، تاریخ شروع الزامی است",
            status_code=422,
            error_code="campaign_starts_on_required",
        )


def ensure_campaign_active(status: CampaignStatus) -> None:
    if status != CampaignStatus.ACTIVE:
        raise AppError(
            "کمپین فعال نیست",
            status_code=409,
            error_code="campaign_not_active",
        )


def ensure_campaign_window(
    starts_on: date | None, ends_on: date | None, *, today: date
) -> None:
    if starts_on is not None and today < starts_on:
        raise AppError(
            "کمپین هنوز شروع نشده است",
            status_code=409,
            error_code="campaign_not_started",
        )
    if ends_on is not None and today > ends_on:
        raise AppError(
            "کمپین به پایان رسیده است",
            status_code=409,
            error_code="campaign_ended",
        )


def ensure_max_applications_per_member(
    current_count: int, max_applications: int | None
) -> None:
    if max_applications is not None and current_count >= max_applications:
        raise AppError(
            "سقف اعمال این کمپین برای این عضو تکمیل شده است",
            status_code=409,
            error_code="campaign_max_applications_exceeded",
        )


def compute_grant_amount(rules: dict | None, base_amount: int | None) -> int:
    rules = rules or {}
    bonus = int(rules.get("earn_bonus_points", 0) or 0)
    if bonus < 0:
        bonus = 0
    if base_amount is not None:
        multiplier = float(rules.get("earn_multiplier", 1.0) or 1.0)
        grant = math.floor(base_amount * multiplier) + bonus
    else:
        grant = bonus
    return max(0, int(grant))


def ensure_positive_grant(grant: int) -> int:
    if grant <= 0:
        raise AppError(
            "مقدار امتیاز قابل اعطا باید بزرگ‌تر از صفر باشد",
            status_code=422,
            error_code="campaign_grant_invalid",
        )
    return grant