use super::entities::{QuotaDefinition, TimePeriod, UsageType};
use crate::common::value_objects::DateTimeStamp;
use chrono::{Datelike, NaiveDate, TimeZone, Utc};

pub struct QuotaCheckResult {
    pub allowed: bool,
    pub current_usage: u64,
    pub limit: u64,
    pub is_unlimited: bool,
}

pub fn check_quota(
    quota: &QuotaDefinition,
    usage_type: UsageType,
    current_usage: u64,
    requested_amount: u64,
) -> QuotaCheckResult {
    if !quota.is_enforced {
        return QuotaCheckResult {
            allowed: true,
            current_usage,
            limit: 0,
            is_unlimited: true,
        };
    }

    let rule = quota.rules.iter().find(|r| r.dimension == usage_type);
    let Some(rule) = rule else {
        return QuotaCheckResult {
            allowed: true,
            current_usage,
            limit: 0,
            is_unlimited: true,
        };
    };

    if rule.is_unlimited {
        return QuotaCheckResult {
            allowed: true,
            current_usage,
            limit: 0,
            is_unlimited: true,
        };
    }

    QuotaCheckResult {
        allowed: current_usage + requested_amount <= rule.limit_value,
        current_usage,
        limit: rule.limit_value,
        is_unlimited: false,
    }
}

pub fn period_start(period: TimePeriod) -> Option<DateTimeStamp> {
    let now = Utc::now();
    match period {
        TimePeriod::Daily => {
            let start = NaiveDate::from_ymd_opt(now.year(), now.month(), now.day())
                .expect("valid date")
                .and_hms_opt(0, 0, 0)
                .expect("valid time");
            Some(DateTimeStamp::from_datetime(Utc.from_utc_datetime(&start)))
        }
        TimePeriod::Monthly => {
            let start = NaiveDate::from_ymd_opt(now.year(), now.month(), 1)
                .expect("valid date")
                .and_hms_opt(0, 0, 0)
                .expect("valid time");
            Some(DateTimeStamp::from_datetime(Utc.from_utc_datetime(&start)))
        }
        TimePeriod::Lifetime => None,
    }
}