use crate::error::{AppError, ErrorCode};
use crate::state::AppState;

use chrono::{Duration, Utc};
use std::net::IpAddr;

pub async fn consume_anonymous_units(
    state: &AppState,
    session_id: &str,
    ip: IpAddr,
    units: u32,
) -> Result<(), AppError> {
    if units == 0 {
        return Ok(());
    }

    let date = utc8_date();
    let session_key = format!("anon_quota:{session_id}:{date}");
    let ip_key = format!("anon_quota_ip:{ip}:{date}");

    let mut conn = state.redis.clone();

    let limit = state.config.anon_daily_units as i64;
    let ttl_seconds = 48 * 60 * 60;
    let inc = units as i64;

    let script = redis::Script::new(
        r#"
        local limit = tonumber(ARGV[1])
        local ttl = tonumber(ARGV[2])
        local inc = tonumber(ARGV[3])

        local v1 = tonumber(redis.call('GET', KEYS[1]) or '0')
        local v2 = tonumber(redis.call('GET', KEYS[2]) or '0')

        if v1 + inc > limit or v2 + inc > limit then
          return -1
        end

        v1 = redis.call('INCRBY', KEYS[1], inc)
        v2 = redis.call('INCRBY', KEYS[2], inc)

        if v1 == inc then redis.call('EXPIRE', KEYS[1], ttl) end
        if v2 == inc then redis.call('EXPIRE', KEYS[2], ttl) end

        return v1
        "#,
    );

    let new_value: i64 = script
        .key(session_key)
        .key(ip_key)
        .arg(limit)
        .arg(ttl_seconds)
        .arg(inc)
        .invoke_async(&mut conn)
        .await
        .map_err(|err| AppError::new(ErrorCode::Internal, "匿名配额检查失败").with_source(err))?;

    if new_value < 0 {
        return Err(AppError::new(
            ErrorCode::QuotaExceeded,
            "匿名试用次数已用完（每日 10 次）",
        ));
    }

    Ok(())
}

fn utc8_date() -> String {
    let now = Utc::now() + Duration::hours(8);
    now.format("%Y-%m-%d").to_string()
}