use crate::{db::Pool, error::AppResult, services::{club, pack}};
use uuid::Uuid;

const STREAK_COINS: [i64; 7] = [500, 650, 800, 1000, 1200, 1500, 2000];
// Day 7 (index 6) also grants a pack:
const STREAK_7_PACK: &str = "silver_pack";

#[derive(Debug, serde::Serialize)]
pub struct CheckinStatus {
    pub available: bool,
    pub streak_day: i64,   // current streak (1–7 cycle, 0 if never checked in)
    pub next_reward_coins: i64,
    pub next_reward_pack: Option<&'static str>,
    pub last_checked_in: Option<String>,
}

#[derive(Debug, serde::Serialize)]
pub struct CheckinResult {
    pub coins_awarded: i64,
    pub pack_awarded: Option<String>,
    pub new_streak: i64,
    pub already_claimed: bool,
}

pub async fn get_status(pool: &Pool, profile_id: &str) -> AppResult<CheckinStatus> {
    let row: Option<(i64, String)> = sqlx::query_as(
        "SELECT streak_day, checked_in_at FROM daily_checkins \
         WHERE profile_id = ? ORDER BY checked_in_at DESC LIMIT 1",
    )
    .bind(profile_id)
    .fetch_optional(pool)
    .await?;

    let today = today_date();
    match row {
        None => Ok(CheckinStatus {
            available: true,
            streak_day: 0,
            next_reward_coins: STREAK_COINS[0],
            next_reward_pack: None,
            last_checked_in: None,
        }),
        Some((last_streak, last_at)) => {
            let last_day = &last_at[..10]; // YYYY-MM-DD
            let available = last_day != today.as_str();
            let next_streak = compute_next_streak(last_streak, &last_at);
            let idx = ((next_streak - 1) % 7) as usize;
            Ok(CheckinStatus {
                available,
                streak_day: if available { next_streak } else { last_streak },
                next_reward_coins: STREAK_COINS[idx],
                next_reward_pack: if idx == 6 { Some(STREAK_7_PACK) } else { None },
                last_checked_in: Some(last_at),
            })
        }
    }
}

pub async fn claim(
    pool: &Pool,
    profile_id: &str,
    club_id: &str,
) -> AppResult<CheckinResult> {
    let row: Option<(i64, String)> = sqlx::query_as(
        "SELECT streak_day, checked_in_at FROM daily_checkins \
         WHERE profile_id = ? ORDER BY checked_in_at DESC LIMIT 1",
    )
    .bind(profile_id)
    .fetch_optional(pool)
    .await?;

    let today = today_date();
    if let Some((_, ref last_at)) = row {
        if &last_at[..10] == today.as_str() {
            let last_streak = row.as_ref().map(|(s, _)| *s).unwrap_or(1);
            return Ok(CheckinResult {
                coins_awarded: 0,
                pack_awarded: None,
                new_streak: last_streak,
                already_claimed: true,
            });
        }
    }

    let last_streak = row.as_ref().map(|(s, last_at)| compute_next_streak(*s, last_at)).unwrap_or(1);
    let idx = ((last_streak - 1) % 7) as usize;
    let coins = STREAK_COINS[idx];
    let pack_def = if idx == 6 { Some(STREAK_7_PACK) } else { None };

    club::add_coins(pool, club_id, coins).await?;
    if let Some(def) = pack_def {
        let _ = pack::grant_pack(pool, club_id, def).await;
    }

    let now = chrono::Utc::now().to_rfc3339();
    sqlx::query(
        "INSERT INTO daily_checkins (id, profile_id, club_id, streak_day, coins_awarded, pack_granted, checked_in_at) \
         VALUES (?, ?, ?, ?, ?, ?, ?)",
    )
    .bind(Uuid::new_v4().to_string())
    .bind(profile_id)
    .bind(club_id)
    .bind(last_streak)
    .bind(coins)
    .bind(pack_def)
    .bind(&now)
    .execute(pool)
    .await?;

    Ok(CheckinResult {
        coins_awarded: coins,
        pack_awarded: pack_def.map(String::from),
        new_streak: last_streak,
        already_claimed: false,
    })
}

fn today_date() -> String {
    chrono::Utc::now().format("%Y-%m-%d").to_string()
}

/// If last check-in was yesterday or today → continue streak; otherwise reset to 1.
fn compute_next_streak(last_streak: i64, last_at: &str) -> i64 {
    let last_day = &last_at[..10];
    let today = chrono::Utc::now().date_naive();
    let yesterday = (today - chrono::Days::new(1)).to_string();
    let today_str = today.to_string();
    if last_day == yesterday || last_day == today_str {
        (last_streak % 7) + 1
    } else {
        1
    }
}