// Copyright (C) 2024 Riften Labs AS
//
// This software is licensed under the GNU Affero General Public License (AGPL), version 3.0 or later.
// A copy of the license can be found in the LICENSE file or at https://www.gnu.org/licenses/agpl-3.0.html

use anyhow::Result;
use log::warn;
use rusqlite::Connection;

use crate::db::cauldron::pool::get_pool_period_snapshot;
use crate::db::oracle::get_closest;
use crate::rpc::apy::apyaggregator::APYAggregator;
use crate::rpc::apy::poolperiod::PoolPeriod;
use malachite::base::num::arithmetic::traits::FloorSqrt;
use malachite::Integer;

use rust_decimal::prelude::*;
use rust_decimal::Decimal;
use rust_decimal_macros::dec;

/// Fallback path when Decimal scaling overflows: convert to f64 with clamped exponent.
pub fn overflow_f64_fallback(base: Decimal, decimals: u32) -> f64 {
    let base_f = dec_to_f64_bounded(base);
    let exp = (decimals as i32).clamp(0, 308); // max safe for f64::powi
    let factor_f = 10f64.powi(exp);
    let p = base_f * factor_f;
    if p.is_finite() {
        p
    } else {
        f64::MAX.copysign(p)
    }
}

/// Round to a reasonable scale before conversion (tunable).
pub fn dec_round(d: Decimal, scale: u32) -> Decimal {
    d.round_dp_with_strategy(scale, rust_decimal::RoundingStrategy::MidpointNearestEven)
}

/// Convert Decimal -> f64, guaranteed finite (never NaN/∞). Clamps if needed.
/// Optional: enforce a floor so tiny non-zero values don't collapse to 0.
pub fn dec_to_f64_bounded(d: Decimal) -> f64 {
    if let Some(v) = d.to_f64() {
        if v.is_finite() {
            return v;
        }
    }
    if d.is_sign_negative() {
        -f64::MAX
    } else {
        f64::MAX
    }
}

pub const SATS_PER_BCH: i64 = 100_000_000;
pub const ORACLE_SCALE: i64 = 1_000_000; // match the delphi scale

pub fn usd_per_bch_at_or_before(conn: &Connection, ts: i64) -> Decimal {
    match get_closest(conn, &None, ts) {
        Ok(Some(e)) => {
            Decimal::from_i64(e.oracle_price).unwrap_or(Decimal::ZERO)
                / Decimal::from_i64(ORACLE_SCALE).unwrap() // USD/BCH
        }
        _ => Decimal::ZERO,
    }
}

#[inline]
pub fn pct_change_bp_dec(current: Decimal, past: Decimal) -> i64 {
    if past.is_zero() {
        return 0;
    }

    let tenk = dec!(10000);

    // Compute: ((current / past) - 1) * 10_000  in a safer order:
    // => (current * 10_000 / past) - 10_000
    let scaled_current = match current.checked_mul(tenk) {
        Some(v) => v,
        None => return if current >= past { i64::MAX } else { i64::MIN },
    };

    let ratio_bp = match scaled_current.checked_div(past) {
        Some(v) => v,
        None => return 0, // should not happen (past==0 handled), but be defensive
    };

    let delta_bp = match ratio_bp.checked_sub(tenk) {
        Some(v) => v,
        None => return if current >= past { i64::MAX } else { i64::MIN },
    };

    // Round and convert; clamp if it wouldn't fit in i64
    match delta_bp.round().to_i64() {
        Some(v) => v,
        None => {
            if delta_bp.is_sign_negative() {
                i64::MIN
            } else {
                i64::MAX
            }
        }
    }
}

#[inline]
pub fn compute_score(tvl_sats: u64, vol_30d: u64) -> i64 {
    if tvl_sats == 0 || vol_30d == 0 {
        return 0;
    }

    // score = vol_30d * floor_sqrt(tvl_sats), all in big-int to avoid overflow
    let sqrt_tvl: Integer = Integer::from(tvl_sats).floor_sqrt();
    let score_big: Integer = Integer::from(vol_30d) * sqrt_tvl;

    // Clamp to i64 range (non-negative by construction)
    if score_big > i64::MAX {
        return i64::MAX;
    }

    // Convert safely; fall back to MAX on unexpected parse failure
    match score_big.to_string().parse::<i64>() {
        Ok(v) => v,
        Err(_) => i64::MAX,
    }
}
pub fn resolve_decimals(bcmr_conn: &Connection, crc20_conn: &Connection, token_id: &str) -> u32 {
    // On-chain BCMR (latest by height)
    if let Ok(Some(v)) = bcmr_conn.query_row(
        r#"
        SELECT decimals FROM (
          SELECT b.decimals, a.height,
                 ROW_NUMBER() OVER (PARTITION BY a.token_id ORDER BY a.height DESC) rn
          FROM auth_chain_entry a
          LEFT JOIN bcmr_data b ON a.utxo = b.utxo
          WHERE a.bcmr_data IS NOT NULL AND a.token_id = ?1
        ) s WHERE rn = 1
        "#,
        [token_id],
        |r| r.get::<_, Option<i64>>(0),
    ) {
        let dd = v.max(0) as u32;
        if dd > 0 {
            return dd; // only accept positive
        }
    }

    // Well-known BCMR
    if let Ok(Some(v)) = bcmr_conn.query_row(
        r#"SELECT decimals FROM bcmr_well_known WHERE token_id = ?1 ORDER BY source LIMIT 1"#,
        [token_id],
        |r| r.get::<_, Option<i64>>(0),
    ) {
        let dd = v.max(0) as u32;
        if dd > 0 {
            return dd;
        }
    }

    // CRC20 fallback
    if let Ok(Some(v)) = crc20_conn.query_row(
        r#"SELECT decimals FROM crc20 WHERE token_id = ?1 LIMIT 1"#,
        [token_id],
        |r| r.get::<_, Option<i64>>(0),
    ) {
        let dd = v.max(0) as u32;
        if dd > 0 {
            return dd;
        }
    }

    // Final fallback
    0
}

/// Max safe exponent for 10^d that fits in `rust_decimal` (1e28 fits; 1e29 does not).
pub const MAX_DECIMALS_FOR_SCALING: u32 = 28;

/// Clamp a metadata decimals value to something rust_decimal can represent.
#[inline]
pub fn clamp_decimals(decimals: u32) -> u32 {
    if decimals > MAX_DECIMALS_FOR_SCALING {
        warn!(
            "Clamping decimals {} -> {} to avoid overflow in pow10_dec()",
            decimals, MAX_DECIMALS_FOR_SCALING
        );
    }
    decimals.min(MAX_DECIMALS_FOR_SCALING)
}

#[inline]
pub fn pow10_dec(decimals: u32) -> Decimal {
    // After clamping, powu is safe and exact.
    dec!(10).powu(clamp_decimals(decimals) as u64)
}

#[inline]
pub fn price_from_tvl(tvl_sats: u64, tvl_tokens: u64) -> Option<Decimal> {
    if tvl_tokens == 0 {
        return None;
    }
    let sats = Decimal::from_u64(tvl_sats)?;
    let tokens = Decimal::from_u64(tvl_tokens)?;
    sats.checked_div(tokens)
}

pub fn apy_30d_bp_for_token(conn: &Connection, token_id: &str, now: i64) -> Result<i64> {
    let start = now - 30 * 86_400;

    let pairs = get_pool_period_snapshot(conn, Some(token_id), None, start, now)?;
    let periods = pairs
        .into_iter()
        .filter(|(s, e)| {
            e.timestamp > s.timestamp
                && s.sats > 0
                && s.token_amount > 0
                && e.sats > 0
                && e.token_amount > 0
        })
        .map(|(s, e)| PoolPeriod::new(s, e))
        .collect::<Result<Vec<_>>>()?;

    if periods.is_empty() {
        return Ok(0);
    }

    // v is a PERCENT value, e.g. 5.239 = 5.239%
    let apy_dec =
        APYAggregator::aggregate_apy(periods.into_iter(), Some(start as u64)).map_err(|e| {
            warn!(
                "aggregate_apy failed for token {} over 30d: {}",
                token_id, e
            );
            e
        })?;

    // Percent → basis points (100 bp = 1%)
    let hundred = dec!(100);

    let bp_dec = match apy_dec.checked_mul(hundred) {
        Some(v) => v.round(),
        None => {
            // clamp on overflow instead of panicking
            return Ok(i64::MAX);
        }
    };

    let apy_bp = match bp_dec.to_i64() {
        Some(v) => v,
        None if bp_dec.is_sign_negative() => i64::MIN,
        None => i64::MAX,
    };
    Ok(apy_bp)
}

pub fn resolve_display_labels(
    bcmr_conn: &Connection,
    crc20_conn: &Connection,
    token_id: &str,
) -> Result<(String, String)> {
    // On-chain BCMR (latest by height)
    let mut onchain = bcmr_conn.prepare(
        r#"
        SELECT name, symbol FROM (
          SELECT b.name, b.symbol, a.height,
                 ROW_NUMBER() OVER (PARTITION BY a.token_id ORDER BY a.height DESC) rn
          FROM auth_chain_entry a
          LEFT JOIN bcmr_data b ON a.utxo = b.utxo
          WHERE a.bcmr_data IS NOT NULL AND a.token_id = ?1
        ) s WHERE rn = 1
        "#,
    )?;
    if let Ok(row) = onchain.query_row([token_id], |r| {
        Ok((r.get::<_, String>(0)?, r.get::<_, String>(1)?))
    }) {
        let (name, sym) = row;
        let dn = if !name.is_empty() {
            name
        } else if !sym.is_empty() {
            sym.clone()
        } else {
            token_id.to_string()
        };
        return Ok((dn, sym));
    }

    // Well-known BCMR (pick a deterministic row)
    let mut wk = bcmr_conn.prepare(
        r#"SELECT name, symbol FROM bcmr_well_known WHERE token_id = ?1 ORDER BY source LIMIT 1"#,
    )?;
    if let Ok(row) = wk.query_row([token_id], |r| {
        Ok((r.get::<_, String>(0)?, r.get::<_, String>(1)?))
    }) {
        let (name, sym) = row;
        let dn = if !name.is_empty() {
            name
        } else if !sym.is_empty() {
            sym.clone()
        } else {
            token_id.to_string()
        };
        return Ok((dn, sym));
    }

    // CRC20 fallback
    let mut crc =
        crc20_conn.prepare(r#"SELECT name, symbol FROM crc20 WHERE token_id = ?1 LIMIT 1"#)?;
    if let Ok(row) = crc.query_row([token_id], |r| {
        Ok((r.get::<_, String>(0)?, r.get::<_, String>(1)?))
    }) {
        let (name, sym) = row;
        let dn = if !name.is_empty() {
            name
        } else if !sym.is_empty() {
            sym.clone()
        } else {
            token_id.to_string()
        };
        return Ok((dn, sym));
    }

    // Last resort
    Ok((token_id.to_string(), String::new()))
}