perpl-sdk 0.2.2

//! Tests for the L3 order book.

use std::num::NonZeroU16;

use fastnum::udec64;

use super::*;
use crate::state::Order;

/// Helper to create OrderId from u16 literal in tests.
fn oid(n: u16) -> types::OrderId { NonZeroU16::new(n).expect("test order id must be non-zero") }

/// Helper to create Option<OrderId> from u16 literal in tests.
fn ooid(n: u16) -> Option<types::OrderId> { NonZeroU16::new(n) }

// ============================================================================
// TEST DSL MACROS
// ============================================================================

/// Create an ask order (OpenShort) for L3 testing.
/// ask!(price, size, block, order_id, account_id)
macro_rules! ask {
    ($price:expr, $size:expr, $block:expr, $oid:expr, $aid:expr) => {
        Order::for_l3_testing(
            types::OrderType::OpenShort,
            udec64!($price),
            udec64!($size),
            $block,
            oid($oid),
            $aid,
        )
    };
}

/// Create a bid order (OpenLong) for L3 testing.
/// bid!(price, size, block, order_id, account_id)
macro_rules! bid {
    ($price:expr, $size:expr, $block:expr, $oid:expr, $aid:expr) => {
        Order::for_l3_testing(
            types::OrderType::OpenLong,
            udec64!($price),
            udec64!($size),
            $block,
            oid($oid),
            $aid,
        )
    };
}

/// Assert L2 level state: (price, total_size, num_orders).
macro_rules! assert_level {
    ($book:expr, ask @ $price:expr => ($size:expr, $count:expr)) => {
        let level = $book.ask_level(udec64!($price)).expect("ask level exists");
        assert_eq!(level.size(), udec64!($size), "ask@{} size", $price);
        assert_eq!(level.num_orders(), $count, "ask@{} count", $price);
    };
    ($book:expr, bid @ $price:expr => ($size:expr, $count:expr)) => {
        let level = $book.bid_level(udec64!($price)).expect("bid level exists");
        assert_eq!(level.size(), udec64!($size), "bid@{} size", $price);
        assert_eq!(level.num_orders(), $count, "bid@{} count", $price);
    };
}

/// Assert best ask/bid: best_ask!(book, price, size) or best_ask!(book, none).
macro_rules! assert_best_ask {
    ($book:expr, none) => {
        assert_eq!($book.best_ask(), None, "expected no best ask");
    };
    ($book:expr, $price:expr, $size:expr) => {
        assert_eq!($book.best_ask(), Some((udec64!($price), udec64!($size))), "best ask");
    };
}

macro_rules! assert_best_bid {
    ($book:expr, none) => {
        assert_eq!($book.best_bid(), None, "expected no best bid");
    };
    ($book:expr, $price:expr, $size:expr) => {
        assert_eq!($book.best_bid(), Some((udec64!($price), udec64!($size))), "best bid");
    };
}

/// Assert order exists in book with expected properties.
macro_rules! assert_order {
    ($book:expr, $oid:expr => { price: $price:expr, size: $size:expr, account_id: $aid:expr }) => {
        let order = $book
            .get_order(oid($oid))
            .expect(&format!("order {} exists", $oid));
        assert_eq!(order.price(), udec64!($price), "order {} price", $oid);
        assert_eq!(order.size(), udec64!($size), "order {} size", $oid);
        assert_eq!(order.account_id(), $aid, "order {} account_id", $oid);
    };
}

/// Assert order exists in book with expected properties by client order id.
macro_rules! assert_order_by_client_id {
    ($book:expr, $aid:expr, $client_order_id:expr => { price: $price:expr, size: $size:expr }) => {
        let order = $book
            .get_order_by_client_id($aid, $client_order_id)
            .expect(&format!("order with client ID {} exists", $client_order_id));
        assert_eq!(order.price(), udec64!($price), "order {} price", $client_order_id);
        assert_eq!(order.size(), udec64!($size), "order {} size", $client_order_id);
        assert_eq!(order.account_id(), $aid, "order {} account_id", $client_order_id);
    };
}

/// Assert FIFO order at a price level.
macro_rules! assert_fifo {
    ($book:expr, ask @ $price:expr => [$($oid:expr),*]) => {
        let level = $book.ask_level(udec64!($price)).expect("ask level exists");
        let order_ids: Vec<_> = $book.level_orders(level).map(|o| o.order_id()).collect();
        assert_eq!(order_ids, vec![$(oid($oid)),*], "ask@{} FIFO order", $price);
    };
    ($book:expr, bid @ $price:expr => [$($oid:expr),*]) => {
        let level = $book.bid_level(udec64!($price)).expect("bid level exists");
        let order_ids: Vec<_> = $book.level_orders(level).map(|o| o.order_id()).collect();
        assert_eq!(order_ids, vec![$(oid($oid)),*], "bid@{} FIFO order", $price);
    };
}

// ============================================================================
// L3LEVEL TESTS
// ============================================================================

#[test]
fn l3_level_new_is_empty() {
    let level = BookLevel::new();
    assert!(level.is_empty());
    assert_eq!(level.size(), udec64!(0));
    assert_eq!(level.num_orders(), 0);
    assert!(level.head().is_none());
    assert!(level.tail().is_none());
}

// ============================================================================
// L3BOOK TESTS - L2 API COMPATIBILITY
// ============================================================================

#[test]
fn l3_book_add_ask_order() {
    // Ask orders appear in asks, not bids.
    let mut book = OrderBook::new();
    book.add_order(&ask!(100, 1.0, 1, 1, 1)).unwrap();

    assert_best_ask!(book, 100, 1.0);
    assert_best_bid!(book, none);
    assert_eq!(book.total_orders(), 1);
}

#[test]
fn l3_book_add_bid_order() {
    // Bid orders appear in bids, not asks.
    let mut book = OrderBook::new();
    book.add_order(&bid!(90, 2.0, 1, 1, 1)).unwrap();

    assert_best_bid!(book, 90, 2.0);
    assert_best_ask!(book, none);
    assert_eq!(book.total_orders(), 1);
}

#[test]
fn l3_book_best_prices() {
    // Best ask is lowest price, best bid is highest price.
    let mut book = OrderBook::new();
    book.add_order(&ask!(110, 1.0, 1, 1, 1)).unwrap();
    book.add_order(&ask!(100, 1.0, 2, 2, 2)).unwrap(); // best
    book.add_order(&ask!(120, 1.0, 3, 3, 3)).unwrap();
    book.add_order(&bid!(80, 1.0, 4, 4, 4)).unwrap();
    book.add_order(&bid!(90, 1.0, 5, 5, 5)).unwrap(); // best
    book.add_order(&bid!(70, 1.0, 6, 6, 6)).unwrap();

    assert_best_ask!(book, 100, 1.0);
    assert_best_bid!(book, 90, 1.0);
}

#[test]
fn l3_book_multiple_orders_same_price() {
    // Multiple orders at same price: sizes aggregate, FIFO by insertion order.
    let mut book = OrderBook::new();
    book.add_order(&ask!(100, 1.0, 1, 1, 1)).unwrap();
    book.add_order(&ask!(100, 2.0, 2, 2, 2)).unwrap();
    book.add_order(&ask!(100, 3.0, 3, 3, 3)).unwrap();

    assert_level!(book, ask @ 100 => (6.0, 3));
    assert_fifo!(book, ask @ 100 => [1, 2, 3]); // insertion order
}

#[test]
fn l3_book_ask_impact_single_level() {
    // Impact within one price level.
    let mut book = OrderBook::new();
    book.add_order(&ask!(100, 5.0, 1, 1, 1)).unwrap();

    let impact = book.ask_impact(udec64!(2.0));
    // (impact_price, fillable_size, vwap)
    assert_eq!(impact, Some((udec64!(100), udec64!(2.0), udec64!(100))));
}

#[test]
fn l3_book_ask_impact_multiple_levels() {
    // Impact spanning multiple price levels.
    let mut book = OrderBook::new();
    book.add_order(&ask!(100, 1.0, 1, 1, 1)).unwrap();
    book.add_order(&ask!(110, 2.0, 2, 2, 2)).unwrap();
    book.add_order(&ask!(120, 3.0, 3, 3, 3)).unwrap();

    // Want 2.5: fills 1.0@100 + 1.5@110 = 100 + 165 = 265 / 2.5 = 106
    let impact = book.ask_impact(udec64!(2.5));
    assert_eq!(impact, Some((udec64!(110), udec64!(2.5), udec64!(265) / udec64!(2.5))));
}

#[test]
fn l3_book_bid_impact() {
    // Bid impact works similarly.
    let mut book = OrderBook::new();
    book.add_order(&bid!(100, 2.0, 1, 1, 1)).unwrap();
    book.add_order(&bid!(90, 3.0, 2, 2, 2)).unwrap();

    // Want 3.0: fills 2.0@100 + 1.0@90 = 200 + 90 = 290 / 3.0
    let impact = book.bid_impact(udec64!(3.0));
    assert_eq!(impact, Some((udec64!(90), udec64!(3.0), udec64!(290) / udec64!(3.0))));
}

// ============================================================================
// L3BOOK TESTS - L3 API
// ============================================================================

#[test]
fn l3_book_get_order_by_id() {
    // O(1) lookup by order_id via reverse index.
    let mut book = OrderBook::new();
    book.add_order(&ask!(100, 1.0, 1, 42, 7)).unwrap();

    assert_order!(book, 42 => { price: 100, size: 1.0, account_id: 7 });
}

#[test]
fn l3_book_get_order_by_client_order_id() {
    // O(1) lookup by order_id via reverse index.
    let mut book = OrderBook::new();
    book.add_order(&ask!(110, 1.0, 1, 42, 7).with_client_order_id(123))
        .unwrap();
    book.add_order(&bid!(90, 1.0, 2, 43, 8).with_client_order_id(123))
        .unwrap();

    assert_order_by_client_id!(book, 7, 123 => { price: 110, size: 1.0 });
    assert_order_by_client_id!(book, 8, 123 => { price: 90, size: 1.0 });
}

#[test]
fn l3_book_ask_orders_iterator() {
    // Iterate all asks in price-time priority.
    let mut book = OrderBook::new();
    book.add_order(&ask!(110, 1.0, 1, 1, 1)).unwrap();
    book.add_order(&ask!(100, 1.0, 2, 2, 2)).unwrap(); // best price
    book.add_order(&ask!(110, 1.0, 3, 3, 3)).unwrap(); // same as order 1

    let order_ids: Vec<_> = book.ask_orders().map(|o| o.order_id()).collect();
    // Price 100 first, then price 110 (insertion order within price level: 1, 3)
    assert_eq!(order_ids, vec![oid(2), oid(1), oid(3)]);
}

#[test]
fn l3_book_bid_orders_iterator() {
    // Iterate all bids in price-time priority (highest price first).
    let mut book = OrderBook::new();
    book.add_order(&bid!(90, 1.0, 1, 1, 1)).unwrap();
    book.add_order(&bid!(100, 1.0, 2, 2, 2)).unwrap(); // best price
    book.add_order(&bid!(90, 1.0, 3, 3, 3)).unwrap();

    let order_ids: Vec<_> = book.bid_orders().map(|o| o.order_id()).collect();
    // Price 100 first, then price 90 (insertion order: 1, 3)
    assert_eq!(order_ids, vec![oid(2), oid(1), oid(3)]);
}

#[test]
fn l3_book_level_accessors() {
    // ask_level() and bid_level() return level at specific price.
    let mut book = OrderBook::new();
    book.add_order(&ask!(100, 1.0, 1, 1, 1)).unwrap();
    book.add_order(&ask!(100, 2.0, 2, 2, 2)).unwrap();
    book.add_order(&bid!(90, 3.0, 3, 3, 3)).unwrap();

    assert!(book.ask_level(udec64!(100)).is_some());
    assert!(book.ask_level(udec64!(99)).is_none());
    assert!(book.bid_level(udec64!(90)).is_some());
    assert!(book.bid_level(udec64!(91)).is_none());
}

// ============================================================================
// L3BOOK TESTS - MUTATIONS
// ============================================================================

#[test]
fn l3_book_update_order_same_price() {
    // Partial fill: size decreases, count unchanged, FIFO position preserved.
    let mut book = OrderBook::new();
    let order = ask!(100, 5.0, 1, 1, 1);
    book.add_order(&order).unwrap();
    book.add_order(&ask!(100, 3.0, 2, 2, 2)).unwrap();

    // Order 1 partially filled: 5.0 -> 2.0
    let updated = order.with_size(udec64!(2.0));
    book.update_order(&updated, &book.get_order(order.order_id()).cloned().unwrap())
        .unwrap();

    assert_level!(book, ask @ 100 => (5.0, 2)); // 2.0 + 3.0
    assert_fifo!(book, ask @ 100 => [1, 2]); // FIFO preserved
    assert_order!(book, 1 => { price: 100, size: 2.0, account_id: 1 });
}

#[test]
fn l3_book_remove_order() {
    // Remove order: level updated, empty level pruned.
    let mut book = OrderBook::new();
    let order1 = ask!(100, 2.0, 1, 1, 1);
    let order2 = ask!(100, 3.0, 2, 2, 2);
    book.add_order(&order1).unwrap();
    book.add_order(&order2).unwrap();

    book.remove_order(&book.get_order(order1.order_id()).cloned().unwrap())
        .unwrap();

    assert_level!(book, ask @ 100 => (3.0, 1));
    assert!(book.get_order(oid(1)).is_none());
    assert!(book.get_order(oid(2)).is_some());
}

#[test]
fn l3_book_remove_last_order_at_level() {
    // Removing last order at a level: level is pruned from book.
    let mut book = OrderBook::new();
    let order = ask!(100, 1.0, 1, 1, 1);
    book.add_order(&order).unwrap();
    book.add_order(&ask!(110, 1.0, 2, 2, 2)).unwrap();

    book.remove_order(&book.get_order(order.order_id()).cloned().unwrap())
        .unwrap();

    assert!(book.ask_level(udec64!(100)).is_none());
    assert_best_ask!(book, 110, 1.0);
}

// ============================================================================
// L3BOOK TESTS - MOVE TO BACK (SIZE INCREASE)
// ============================================================================

#[test]
fn l3_book_move_to_back() {
    // Size increase should move order to back of queue.
    let mut book = OrderBook::new();
    let order1 = ask!(100, 1.0, 1, 1, 1);
    let order2 = ask!(100, 2.0, 2, 2, 2);
    let order3 = ask!(100, 3.0, 3, 3, 3);
    book.add_order(&order1).unwrap();
    book.add_order(&order2).unwrap();
    book.add_order(&order3).unwrap();

    // Initial FIFO: [1, 2, 3]
    assert_fifo!(book, ask @ 100 => [1, 2, 3]);

    // Move order 1 to back (simulating size increase)
    let order1_updated = order1.with_size(udec64!(1.5));
    book.move_to_back(&order1_updated, &book.get_order(order1.order_id()).cloned().unwrap())
        .unwrap();

    // New FIFO: [2, 3, 1]
    assert_fifo!(book, ask @ 100 => [2, 3, 1]);
    assert_level!(book, ask @ 100 => (6.5, 3)); // 2.0 + 3.0 + 1.5
    assert_order!(book, 1 => { price: 100, size: 1.5, account_id: 1 });
}

#[test]
fn l3_book_move_to_back_middle_order() {
    // Move middle order to back.
    let mut book = OrderBook::new();
    let order1 = ask!(100, 1.0, 1, 1, 1);
    let order2 = ask!(100, 2.0, 2, 2, 2);
    let order3 = ask!(100, 3.0, 3, 3, 3);
    book.add_order(&order1).unwrap();
    book.add_order(&order2).unwrap();
    book.add_order(&order3).unwrap();

    // Move order 2 to back
    let order2_updated = order2.with_size(udec64!(2.5));
    book.move_to_back(&order2_updated, &book.get_order(order2.order_id()).cloned().unwrap())
        .unwrap();

    // New FIFO: [1, 3, 2]
    assert_fifo!(book, ask @ 100 => [1, 3, 2]);
}

// ============================================================================
// EDGE CASE TESTS
// ============================================================================

#[test]
fn l3_book_empty_book_operations() {
    // Operations on empty book don't panic.
    let book = OrderBook::new();

    assert_best_ask!(book, none);
    assert_best_bid!(book, none);
    assert!(book.ask_impact(udec64!(1.0)).is_none());
    assert!(book.bid_impact(udec64!(1.0)).is_none());
    assert!(book.get_order(oid(1)).is_none());
    assert_eq!(book.total_orders(), 0);
}

#[test]
fn l3_book_order_id_reuse() {
    // Same order_id can be reused after removal (different block).
    let mut book = OrderBook::new();
    let order1 = ask!(100, 1.0, 1, 42, 1);
    book.add_order(&order1).unwrap();
    book.remove_order(&book.get_order(order1.order_id()).cloned().unwrap())
        .unwrap();

    // New order with same ID but different block
    let order2 = ask!(110, 2.0, 5, 42, 2);
    book.add_order(&order2).unwrap();

    assert_order!(book, 42 => { price: 110, size: 2.0, account_id: 2 });
    assert_eq!(book.total_orders(), 1);
}

#[test]
fn l3_book_account_id_stored() {
    // Account ID is correctly stored and retrievable.
    let mut book = OrderBook::new();

    book.add_order(&ask!(100, 1.0, 1, 1, 10)).unwrap(); // account_id = 10
    book.add_order(&ask!(100, 2.0, 2, 2, 20)).unwrap(); // account_id = 20

    let order1 = book.get_order(oid(1)).unwrap();
    let order2 = book.get_order(oid(2)).unwrap();
    assert_eq!(order1.account_id(), 10);
    assert_eq!(order2.account_id(), 20);
}

#[test]
fn l3_book_remove_nonexistent() {
    // Removing nonexistent order returns an error.
    let mut book = OrderBook::new();
    book.add_order(&ask!(100, 1.0, 1, 1, 10)).unwrap(); // to allocate price level

    let result = book.remove_order(&BookOrder::new(ask!(100, 1.0, 1, 99, 10)));
    assert!(matches!(
        result,
        Err(OrderBookError::OrderNotFound { order_id }) if order_id == oid(99)
    ));
    assert_eq!(book.total_orders(), 1);
}

#[test]
fn l3_book_update_nonexistent() {
    // Updating nonexistent order returns an error.
    let mut book = OrderBook::new();
    let order = ask!(100, 1.0, 1, 99, 1);

    let result = book.update_order(&order.with_size(udec64!(0.5)), &BookOrder::new(order));
    assert!(matches!(
        result,
        Err(OrderBookError::OrderNotFound { order_id }) if order_id == oid(99)
    ));
    assert_eq!(book.total_orders(), 0);
}

// ============================================================================
// ERROR CASE TESTS
// ============================================================================

#[test]
fn l3_book_error_add_duplicate_order() {
    // Adding an order with the same ID twice returns an error.
    let mut book = OrderBook::new();
    let order = ask!(100, 1.0, 1, 42, 1);

    book.add_order(&order).unwrap();
    let result = book.add_order(&order);

    assert!(matches!(
        result,
        Err(OrderBookError::OrderAlreadyExists {
            order_id,
            existing_price,
            ..
        }) if order_id == oid(42) && existing_price == udec64!(100)
    ));
    assert_eq!(book.total_orders(), 1);
}

#[test]
fn l3_book_error_add_zero_size() {
    // Adding an order with zero size returns an error.
    let mut book = OrderBook::new();
    let order = ask!(100, 0.0, 1, 1, 1);

    let result = book.add_order(&order);
    assert!(matches!(
        result,
        Err(OrderBookError::InvalidOrderSize { order_id, size }) if order_id == oid(1) && size == udec64!(0)
    ));
    assert_eq!(book.total_orders(), 0);
}

#[test]
fn l3_book_error_add_zero_price() {
    // Adding an order with zero price returns an error.
    let mut book = OrderBook::new();
    let order = ask!(0, 1.0, 1, 1, 1);

    let result = book.add_order(&order);
    assert!(matches!(
        result,
        Err(OrderBookError::InvalidOrderPrice { order_id, price }) if order_id == oid(1) && price == udec64!(0)
    ));
    assert_eq!(book.total_orders(), 0);
}

#[test]
fn l3_book_error_update_to_zero_size() {
    // Updating an order to zero size returns an error.
    let mut book = OrderBook::new();
    let order = ask!(100, 1.0, 1, 1, 1);
    book.add_order(&order).unwrap();

    let updated = order.with_size(udec64!(0.0));
    let result = book.update_order(&updated, &book.get_order(order.order_id()).cloned().unwrap());

    assert!(matches!(
        result,
        Err(OrderBookError::InvalidOrderSize { order_id, size }) if order_id == oid(1) && size == udec64!(0)
    ));
    // Order should still exist with original size
    assert_order!(book, 1 => { price: 100, size: 1.0, account_id: 1 });
}

// ============================================================================
// COMPREHENSIVE SCENARIO TESTS
// ============================================================================

#[test]
fn scenario_order_book_lifecycle() {
    // Full lifecycle: place -> partial fill -> cancel remaining.
    //
    // Block 1: Alice places ask 100@1.0
    // Block 2: Bob places ask 100@2.0
    // Block 3: Alice's order partially filled (1.0 -> 0.3)
    // Block 4: Alice cancels remaining
    //
    // Expected: Only Bob's order remains.

    let mut book = OrderBook::new();

    // Block 1: Alice places
    let alice_order = ask!(100, 1.0, 1, 1, 1);
    book.add_order(&alice_order).unwrap();
    assert_level!(book, ask @ 100 => (1.0, 1));

    // Block 2: Bob places
    let bob_order = ask!(100, 2.0, 2, 2, 2);
    book.add_order(&bob_order).unwrap();
    assert_level!(book, ask @ 100 => (3.0, 2));
    assert_fifo!(book, ask @ 100 => [1, 2]);

    // Block 3: Alice partially filled
    let alice_updated = alice_order.with_size(udec64!(0.3));
    book.update_order(&alice_updated, &book.get_order(alice_order.order_id()).cloned().unwrap())
        .unwrap();
    assert_level!(book, ask @ 100 => (2.3, 2));
    assert_fifo!(book, ask @ 100 => [1, 2]); // FIFO preserved

    // Block 4: Alice cancels
    book.remove_order(&book.get_order(alice_updated.order_id()).cloned().unwrap())
        .unwrap();
    assert_level!(book, ask @ 100 => (2.0, 1));
    assert_fifo!(book, ask @ 100 => [2]);
}

#[test]
fn scenario_multi_level_book() {
    // Multi-level book with asks and bids.
    //
    // Asks: 100@1.0, 110@2.0, 120@3.0
    // Bids: 90@1.5, 80@2.5, 70@3.5
    //
    // Verify all L2 and L3 accessors work correctly.

    let mut book = OrderBook::new();

    // Build ask side
    book.add_order(&ask!(100, 1.0, 1, 1, 1)).unwrap();
    book.add_order(&ask!(110, 2.0, 2, 2, 2)).unwrap();
    book.add_order(&ask!(120, 3.0, 3, 3, 3)).unwrap();

    // Build bid side
    book.add_order(&bid!(90, 1.5, 4, 4, 4)).unwrap();
    book.add_order(&bid!(80, 2.5, 5, 5, 5)).unwrap();
    book.add_order(&bid!(70, 3.5, 6, 6, 6)).unwrap();

    // L2 checks
    assert_best_ask!(book, 100, 1.0);
    assert_best_bid!(book, 90, 1.5);
    assert_eq!(book.total_orders(), 6);

    // All 3 ask levels exist
    assert!(book.ask_level(udec64!(100)).is_some());
    assert!(book.ask_level(udec64!(110)).is_some());
    assert!(book.ask_level(udec64!(120)).is_some());

    // All 3 bid levels exist
    assert!(book.bid_level(udec64!(90)).is_some());
    assert!(book.bid_level(udec64!(80)).is_some());
    assert!(book.bid_level(udec64!(70)).is_some());

    // L3 iteration order
    let ask_ids: Vec<_> = book.ask_orders().map(|o| o.order_id()).collect();
    assert_eq!(ask_ids, vec![oid(1), oid(2), oid(3)]); // price order: 100, 110, 120

    let bid_ids: Vec<_> = book.bid_orders().map(|o| o.order_id()).collect();
    assert_eq!(bid_ids, vec![oid(4), oid(5), oid(6)]); // price order: 90, 80, 70
}

#[test]
fn scenario_size_increase_loses_priority() {
    // Scenario: Three orders at same price, middle one increases size.
    //
    // Initial: [A, B, C] at price 100
    // B increases size: B loses priority
    // Final: [A, C, B]

    let mut book = OrderBook::new();
    let a = ask!(100, 1.0, 1, 1, 1);
    let b = ask!(100, 2.0, 2, 2, 2);
    let c = ask!(100, 3.0, 3, 3, 3);

    book.add_order(&a).unwrap();
    book.add_order(&b).unwrap();
    book.add_order(&c).unwrap();

    assert_fifo!(book, ask @ 100 => [1, 2, 3]);

    // B increases size: 2.0 -> 2.5
    let b_updated = b.with_size(udec64!(2.5));
    book.move_to_back(&b_updated, &book.get_order(b.order_id()).cloned().unwrap())
        .unwrap();

    assert_fifo!(book, ask @ 100 => [1, 3, 2]);
    assert_level!(book, ask @ 100 => (6.5, 3)); // 1.0 + 3.0 + 2.5
}

#[test]
fn scenario_size_decrease_keeps_priority() {
    // Scenario: Three orders at same price, middle one decreases size.
    //
    // Initial: [A, B, C] at price 100
    // B decreases size: B keeps priority
    // Final: [A, B, C]

    let mut book = OrderBook::new();
    let a = ask!(100, 1.0, 1, 1, 1);
    let b = ask!(100, 2.0, 2, 2, 2);
    let c = ask!(100, 3.0, 3, 3, 3);

    book.add_order(&a).unwrap();
    book.add_order(&b).unwrap();
    book.add_order(&c).unwrap();

    assert_fifo!(book, ask @ 100 => [1, 2, 3]);

    // B decreases size: 2.0 -> 1.5 (use update_order, not move_to_back)
    let b_updated = b.with_size(udec64!(1.5));
    book.update_order(&b_updated, &book.get_order(b.order_id()).cloned().unwrap())
        .unwrap();

    assert_fifo!(book, ask @ 100 => [1, 2, 3]); // Order preserved
    assert_level!(book, ask @ 100 => (5.5, 3)); // 1.0 + 1.5 + 3.0
}

// ============================================================================
// SNAPSHOT RECONSTRUCTION TESTS
// ============================================================================

#[test]
fn snapshot_single_order() {
    // Reconstruct a single order from snapshot.
    let mut book = OrderBook::new();
    let order = ask!(100, 1.0, 1, 1, 1);

    book.add_orders_from_snapshot(&[order]).unwrap();

    assert_eq!(book.total_orders(), 1);
    assert_order!(book, 1 => { price: 100, size: 1.0, account_id: 1 });
    assert_best_ask!(book, 100, 1.0);
}

#[test]
fn snapshot_multiple_orders_same_level() {
    // Reconstruct multiple orders at the same price level.
    // The FIFO order should be determined by the linked list pointers.
    let mut book = OrderBook::new();

    // Create orders with linked list pointers
    let order1 = Order::for_l3_testing_with_links(
        types::OrderType::OpenShort,
        udec64!(100),
        udec64!(1.0),
        1,
        oid(1),
        1,
        None,    // prev
        ooid(2), // next
    );
    let order2 = Order::for_l3_testing_with_links(
        types::OrderType::OpenShort,
        udec64!(100),
        udec64!(2.0),
        2,
        oid(2),
        2,
        ooid(1), // prev
        ooid(3), // next
    );
    let order3 = Order::for_l3_testing_with_links(
        types::OrderType::OpenShort,
        udec64!(100),
        udec64!(3.0),
        3,
        oid(3),
        3,
        ooid(2), // prev
        None,    // next
    );

    // Add in shuffled order - linked list should still be reconstructed correctly
    book.add_orders_from_snapshot(&[order2, order3, order1])
        .unwrap();

    assert_eq!(book.total_orders(), 3);
    assert_level!(book, ask @ 100 => (6.0, 3));
    assert_fifo!(book, ask @ 100 => [1, 2, 3]); // FIFO from linked list
}

#[test]
fn snapshot_multiple_levels() {
    // Reconstruct orders at multiple price levels.
    let mut book = OrderBook::new();

    let orders = [
        ask!(100, 1.0, 1, 1, 1),
        ask!(110, 2.0, 2, 2, 2),
        bid!(90, 1.5, 3, 3, 3),
        bid!(80, 2.5, 4, 4, 4),
    ];

    book.add_orders_from_snapshot(&orders).unwrap();

    assert_eq!(book.total_orders(), 4);
    assert_best_ask!(book, 100, 1.0);
    assert_best_bid!(book, 90, 1.5);
}

// ============================================================================
// LINKED LIST INTEGRITY TESTS
// ============================================================================

#[test]
fn linked_list_head_tail_single_order() {
    // Single order: head and tail point to the same order.
    let mut book = OrderBook::new();
    book.add_order(&ask!(100, 1.0, 1, 1, 1)).unwrap();

    let level = book.ask_level(udec64!(100)).unwrap();
    assert!(level.head().is_some());
    assert!(level.tail().is_some());
    assert_eq!(level.head(), level.tail());
}

#[test]
fn linked_list_head_tail_multiple_orders() {
    // Multiple orders: head is first, tail is last.
    let mut book = OrderBook::new();
    book.add_order(&ask!(100, 1.0, 1, 1, 1)).unwrap();
    book.add_order(&ask!(100, 2.0, 2, 2, 2)).unwrap();
    book.add_order(&ask!(100, 3.0, 3, 3, 3)).unwrap();

    let level = book.ask_level(udec64!(100)).unwrap();
    let head = level.head().unwrap();
    let tail = level.tail().unwrap();

    // Head should be order 1, tail should be order 3
    assert_eq!(head, oid(1));
    assert_eq!(tail, oid(3));

    // Head has no prev, tail has no next
    let head_order = book.get_order(head).unwrap();
    let tail_order = book.get_order(tail).unwrap();
    assert!(head_order.prev().is_none());
    assert!(tail_order.next().is_none());
}

#[test]
fn linked_list_remove_head() {
    // Removing head order updates the level head.
    let mut book = OrderBook::new();
    let order1 = &ask!(100, 1.0, 1, 1, 1);
    let order2 = &ask!(100, 2.0, 2, 2, 2);
    book.add_order(order1).unwrap();
    book.add_order(order2).unwrap();

    book.remove_order(&book.get_order(order1.order_id()).cloned().unwrap())
        .unwrap();

    let level = book.ask_level(udec64!(100)).unwrap();
    let head = level.head().unwrap();
    assert_eq!(head, oid(2));
    let head_order = book.get_order(head).unwrap();
    assert!(head_order.prev().is_none()); // New head has no prev
}

#[test]
fn linked_list_remove_tail() {
    // Removing tail order updates the level tail.
    let mut book = OrderBook::new();
    let order1 = &ask!(100, 1.0, 1, 1, 1);
    let order2 = &ask!(100, 2.0, 2, 2, 2);
    book.add_order(order1).unwrap();
    book.add_order(order2).unwrap();

    book.remove_order(&book.get_order(order2.order_id()).cloned().unwrap())
        .unwrap();

    let level = book.ask_level(udec64!(100)).unwrap();
    let tail = level.tail().unwrap();
    assert_eq!(tail, oid(1));
    let tail_order = book.get_order(tail).unwrap();
    assert!(tail_order.next().is_none()); // New tail has no next
}

#[test]
fn linked_list_remove_middle() {
    // Removing middle order links neighbors correctly.
    let mut book = OrderBook::new();
    let order1 = &ask!(100, 1.0, 1, 1, 1);
    let order2 = &ask!(100, 2.0, 2, 2, 2);
    let order3 = &ask!(100, 3.0, 3, 3, 3);
    book.add_order(order1).unwrap();
    book.add_order(order2).unwrap();
    book.add_order(order3).unwrap();

    book.remove_order(&book.get_order(order2.order_id()).cloned().unwrap())
        .unwrap();

    // FIFO should now be [1, 3]
    assert_fifo!(book, ask @ 100 => [1, 3]);

    // Check links
    let level = book.ask_level(udec64!(100)).unwrap();
    let head = level.head().unwrap();
    let tail = level.tail().unwrap();
    assert_eq!(head, oid(1));
    assert_eq!(tail, oid(3));

    let head_order = book.get_order(head).unwrap();
    let tail_order = book.get_order(tail).unwrap();
    assert_eq!(head_order.next(), Some(tail)); // 1's next is 3
    assert_eq!(tail_order.prev(), Some(head)); // 3's prev is 1
}

// ============================================================================
// ADDITIONAL EDGE CASE TESTS
// ============================================================================

#[test]
fn move_to_back_already_at_back() {
    // Order already at back of queue just updates data, no relink needed.
    let mut book = OrderBook::new();
    let order1 = ask!(100, 1.0, 1, 1, 1);
    let order2 = ask!(100, 2.0, 2, 2, 2);
    book.add_order(&order1).unwrap();
    book.add_order(&order2).unwrap();

    assert_fifo!(book, ask @ 100 => [1, 2]);

    // Move order 2 (already at back) to back with size increase
    let order2_updated = order2.with_size(udec64!(3.0));
    book.move_to_back(&order2_updated, &book.get_order(order2.order_id()).cloned().unwrap())
        .unwrap();

    // FIFO unchanged, size updated
    assert_fifo!(book, ask @ 100 => [1, 2]);
    assert_order!(book, 2 => { price: 100, size: 3.0, account_id: 2 });
    assert_level!(book, ask @ 100 => (4.0, 2)); // 1.0 + 3.0
}

#[test]
fn move_to_back_single_order() {
    // Single order move_to_back is a no-op relink (just update data).
    let mut book = OrderBook::new();
    let order = ask!(100, 1.0, 1, 1, 1);
    book.add_order(&order).unwrap();

    let order_updated = order.with_size(udec64!(2.0));
    book.move_to_back(&order_updated, &book.get_order(order.order_id()).cloned().unwrap())
        .unwrap();

    assert_fifo!(book, ask @ 100 => [1]);
    assert_order!(book, 1 => { price: 100, size: 2.0, account_id: 1 });
}

#[test]
fn snapshot_orphaned_orders_no_links() {
    // Snapshot with orders that have no linked list pointers
    // (e.g., each order is alone in its price level, or data is incomplete).
    let mut book = OrderBook::new();

    // Orders at same price but with no explicit links (simulates incomplete data)
    let order1 = Order::for_l3_testing_with_links(
        types::OrderType::OpenShort,
        udec64!(100),
        udec64!(1.0),
        1,
        oid(1),
        1,
        None, // no prev
        None, // no next
    );
    let order2 = Order::for_l3_testing_with_links(
        types::OrderType::OpenShort,
        udec64!(100),
        udec64!(2.0),
        2,
        oid(2),
        2,
        None, // no prev
        None, // no next
    );

    book.add_orders_from_snapshot(&[order1, order2]).unwrap();

    // Both orders should be in the book
    assert_eq!(book.total_orders(), 2);
    assert_level!(book, ask @ 100 => (3.0, 2));

    // When links are missing, we still have valid head/tail (at least one order is
    // head, one is tail)
    let level = book.ask_level(udec64!(100)).unwrap();
    assert!(level.head().is_some());
    assert!(level.tail().is_some());
}

#[test]
fn interleaved_ask_bid_operations() {
    // Test interleaved operations on both sides of the book.
    let mut book = OrderBook::new();

    // Add asks and bids interleaved
    let order1 = ask!(100, 1.0, 1, 1, 1);
    let order2 = bid!(90, 1.5, 2, 2, 2);
    let order3 = ask!(100, 2.0, 3, 3, 3);
    let order4 = bid!(90, 2.5, 4, 4, 4);
    book.add_order(&order1).unwrap();
    book.add_order(&order2).unwrap();
    book.add_order(&order3).unwrap();
    book.add_order(&order4).unwrap();

    assert_level!(book, ask @ 100 => (3.0, 2));
    assert_level!(book, bid @ 90 => (4.0, 2));
    assert_fifo!(book, ask @ 100 => [1, 3]);
    assert_fifo!(book, bid @ 90 => [2, 4]);

    // Remove from both sides
    book.remove_order(&book.get_order(order1.order_id()).cloned().unwrap())
        .unwrap();
    book.remove_order(&book.get_order(order2.order_id()).cloned().unwrap())
        .unwrap();

    assert_level!(book, ask @ 100 => (2.0, 1));
    assert_level!(book, bid @ 90 => (2.5, 1));
    assert_fifo!(book, ask @ 100 => [3]);
    assert_fifo!(book, bid @ 90 => [4]);
}

#[test]
fn move_nonexistent_order() {
    // Move to back on nonexistent order returns error.
    let mut book = OrderBook::new();
    book.add_order(&ask!(100, 1.0, 1, 1, 1)).unwrap(); // to allocate price level
    let order = ask!(100, 1.0, 1, 99, 1); // order_id = 99, not in book

    let result = book.move_to_back(&order, &BookOrder::new(order));
    assert!(
        matches!(
            result,
            Err(OrderBookError::OrderNotFound { order_id }) if order_id == oid(99)
        ),
        "result: {:?}",
        result
    );
}

// ============================================================================
// STATE INCONSISTENCY TESTS (LevelNotFound)
// ============================================================================

#[test]
fn level_not_found_on_update_order() {
    // Simulate state inconsistency: order exists but level was removed
    let mut book = OrderBook::new();
    let order = ask!(100, 1.0, 1, 1, 1);
    book.add_order(&order).unwrap();

    // Force remove the level (simulating corruption)
    book.force_remove_level(types::OrderSide::Ask, udec64!(100));

    // Try to update the order - should fail with LevelNotFound
    let updated = order.with_size(udec64!(0.5));
    let result = book.update_order(&updated, &book.get_order(order.order_id()).cloned().unwrap());
    assert!(matches!(
        result,
        Err(OrderBookError::LevelNotFound { price, side })
        if price == udec64!(100) && side == types::OrderSide::Ask
    ));
}

#[test]
fn level_not_found_on_remove_order() {
    let mut book = OrderBook::new();
    let order = ask!(100, 1.0, 1, 1, 1);
    book.add_order(&order).unwrap();

    // Force remove the level
    book.force_remove_level(types::OrderSide::Ask, udec64!(100));

    // Try to remove the order - should fail with LevelNotFound
    let result = book.remove_order(&book.get_order(order.order_id()).cloned().unwrap());
    assert!(matches!(
        result,
        Err(OrderBookError::LevelNotFound { price, side })
        if price == udec64!(100) && side == types::OrderSide::Ask
    ));
}

#[test]
fn level_not_found_on_move_to_back() {
    let mut book = OrderBook::new();
    let order = ask!(100, 1.0, 1, 1, 1);
    book.add_order(&order).unwrap();

    // Force remove the level
    book.force_remove_level(types::OrderSide::Ask, udec64!(100));

    // Try to move to back - should fail with LevelNotFound
    let updated = order.with_size(udec64!(1.5));
    let result = book.move_to_back(&updated, &book.get_order(order.order_id()).cloned().unwrap());
    assert!(matches!(
        result,
        Err(OrderBookError::LevelNotFound { price, side })
        if price == udec64!(100) && side == types::OrderSide::Ask
    ));
}

// ============================================================================
// IMPACT NOTIONAL TESTS
// ============================================================================
//
// Tests for `ask_impact_notional` and `bid_impact_notional`.
// Return type: Option<(price, filled_size, vwap, filled_notional)>
//   - price: last level price touched (the impact price)
//   - filled_size: total size filled across all levels
//   - vwap: volume-weighted average price (filled_notional / filled_size)
//   - filled_notional: total notional filled (sum of price * size per level)

use fastnum::{UD128, udec128};

/// Build an `OrderBook` with ask and/or bid inventory at specified price
/// levels.
///
/// Each entry is `(price, &[sizes])` where `sizes` are individual order sizes
/// at that price level. Orders are assigned sequential IDs starting from 1.
///
/// Ask levels are sorted ascending (best ask first) and bid levels are sorted
/// descending (best bid first) by the book's BTreeMap, regardless of insertion
/// order.
fn book_with_inventory(ask_levels: &[(u64, &[u64])], bid_levels: &[(u64, &[u64])]) -> OrderBook {
    let mut book = OrderBook::new();
    let mut next_oid: u16 = 1;
    for &(price, sizes) in ask_levels {
        for &size in sizes {
            let order = Order::for_l3_testing(
                types::OrderType::OpenShort,
                UD64::from_u64(price),
                UD64::from_u64(size),
                0,
                NonZeroU16::new(next_oid).unwrap(),
                0,
            );
            book.add_order(&order).unwrap();
            next_oid += 1;
        }
    }
    for &(price, sizes) in bid_levels {
        for &size in sizes {
            let order = Order::for_l3_testing(
                types::OrderType::OpenLong,
                UD64::from_u64(price),
                UD64::from_u64(size),
                0,
                NonZeroU16::new(next_oid).unwrap(),
                0,
            );
            book.add_order(&order).unwrap();
            next_oid += 1;
        }
    }
    book
}

// 1. Empty book, want_notional > 0 → None

#[test]
fn impact_notional_empty_book_ask() {
    let book = OrderBook::new();
    assert_eq!(book.ask_impact_notional(udec128!(1000)), None);
}

#[test]
fn impact_notional_empty_book_bid() {
    let book = OrderBook::new();
    assert_eq!(book.bid_impact_notional(udec128!(1000)), None);
}

// 2. Cross-talk: only opposing inventory → None

#[test]
fn impact_notional_crosstalk_ask_with_only_bid_inventory() {
    let book = book_with_inventory(&[], &[(100, &[10])]);
    assert_eq!(book.ask_impact_notional(udec128!(500)), None);
}

#[test]
fn impact_notional_crosstalk_bid_with_only_ask_inventory() {
    let book = book_with_inventory(&[(100, &[10])], &[]);
    assert_eq!(book.bid_impact_notional(udec128!(500)), None);
}

// 3. Inventory exists, want_notional = 0 → None

#[test]
fn impact_notional_zero_notional_ask() {
    let book = book_with_inventory(&[(100, &[10])], &[]);
    assert_eq!(book.ask_impact_notional(UD128::ZERO), None);
}

#[test]
fn impact_notional_zero_notional_bid() {
    let book = book_with_inventory(&[], &[(100, &[10])]);
    assert_eq!(book.bid_impact_notional(UD128::ZERO), None);
}

// 4. Single level, half inventory
//
// Setup: 3 orders at price 100, sizes [10, 20, 30] → total_size=60,
//        level_notional=6000.
// Want: 3000 (half). partial_size = 3000/100 = 30. vwap = 3000/30 = 100.

#[test]
fn impact_notional_single_level_half_ask() {
    let book = book_with_inventory(&[(100, &[10, 20, 30])], &[]);
    let result = book.ask_impact_notional(udec128!(3000));
    assert_eq!(result, Some((udec64!(100), udec64!(30), udec64!(100), udec128!(3000))));
}

#[test]
fn impact_notional_single_level_half_bid() {
    let book = book_with_inventory(&[], &[(100, &[10, 20, 30])]);
    let result = book.bid_impact_notional(udec128!(3000));
    assert_eq!(result, Some((udec64!(100), udec64!(30), udec64!(100), udec128!(3000))));
}

// 5. Single level, full inventory
//
// Want: 6000 (exact match). partial_size = 6000/100 = 60. vwap = 100.

#[test]
fn impact_notional_single_level_full_ask() {
    let book = book_with_inventory(&[(100, &[10, 20, 30])], &[]);
    let result = book.ask_impact_notional(udec128!(6000));
    assert_eq!(result, Some((udec64!(100), udec64!(60), udec64!(100), udec128!(6000))));
}

#[test]
fn impact_notional_single_level_full_bid() {
    let book = book_with_inventory(&[], &[(100, &[10, 20, 30])]);
    let result = book.bid_impact_notional(udec128!(6000));
    assert_eq!(result, Some((udec64!(100), udec64!(60), udec64!(100), udec128!(6000))));
}

// 6. Single level, exceeding inventory → partial fill
//
// Want: 7000, but only 6000 available. Returns all inventory.
// filled_size = 60, filled_notional = 6000, vwap = 6000/60 = 100.

#[test]
fn impact_notional_single_level_exceeding_ask() {
    let book = book_with_inventory(&[(100, &[10, 20, 30])], &[]);
    let result = book.ask_impact_notional(udec128!(7000));
    assert_eq!(result, Some((udec64!(100), udec64!(60), udec64!(100), udec128!(6000))));
}

#[test]
fn impact_notional_single_level_exceeding_bid() {
    let book = book_with_inventory(&[], &[(100, &[10, 20, 30])]);
    let result = book.bid_impact_notional(udec128!(7000));
    assert_eq!(result, Some((udec64!(100), udec64!(60), udec64!(100), udec128!(6000))));
}

// 7. Multiple levels, reaching into third level
//
// Ask levels (walked ascending): 100×10, 200×20, 300×30
//   notionals: 1000, 4000, 9000 → total 14000
// Want: 8000. Consumes level 100 (1000) + level 200 (4000) = 5000,
//   then 3000 from level 300: partial_size = 3000/300 = 10.
//   filled_size = 10 + 20 + 10 = 40, vwap = 8000/40 = 200.
//
// Bid levels (walked descending): 300×10, 200×20, 100×30
//   notionals: 3000, 4000, 3000 → total 10000
// Want: 8000. Consumes level 300 (3000) + level 200 (4000) = 7000,
//   then 1000 from level 100: partial_size = 1000/100 = 10.
//   filled_size = 10 + 20 + 10 = 40, vwap = 8000/40 = 200.

#[test]
fn impact_notional_multi_level_partial_ask() {
    let book = book_with_inventory(&[(100, &[10]), (200, &[20]), (300, &[30])], &[]);
    let result = book.ask_impact_notional(udec128!(8000));
    assert_eq!(result, Some((udec64!(300), udec64!(40), udec64!(200), udec128!(8000))));
}

#[test]
fn impact_notional_multi_level_partial_bid() {
    let book = book_with_inventory(&[], &[(300, &[10]), (200, &[20]), (100, &[30])]);
    let result = book.bid_impact_notional(udec128!(8000));
    assert_eq!(result, Some((udec64!(100), udec64!(40), udec64!(200), udec128!(8000))));
}

// 8. Multiple levels, exceeding all inventory → partial fill
//
// Ask levels: 100×10 + 200×20 + 300×30 = total notional 14000, want 15000.
//   filled_size = 60, filled_notional = 14000, vwap = 14000/60 ≈ 233.33.
// Bid levels: 300×10 + 200×20 + 100×30 = total notional 10000, want 11000.
//   filled_size = 60, filled_notional = 10000, vwap = 10000/60 ≈ 166.67.

#[test]
fn impact_notional_multi_level_exceeding_ask() {
    let book = book_with_inventory(&[(100, &[10]), (200, &[20]), (300, &[30])], &[]);
    let result = book.ask_impact_notional(udec128!(15000));
    let (price, filled_size, _vwap, filled_notional) = result.unwrap();
    assert_eq!(price, udec64!(300));
    assert_eq!(filled_size, udec64!(60));
    assert_eq!(filled_notional, udec128!(14000));
}

#[test]
fn impact_notional_multi_level_exceeding_bid() {
    let book = book_with_inventory(&[], &[(300, &[10]), (200, &[20]), (100, &[30])]);
    let result = book.bid_impact_notional(udec128!(11000));
    let (price, filled_size, _vwap, filled_notional) = result.unwrap();
    assert_eq!(price, udec64!(100));
    assert_eq!(filled_size, udec64!(60));
    assert_eq!(filled_notional, udec128!(10000));
}

// 9. want_notional exceeding UD64 range → partial fill
//
// Verifies that UD128 want_notional values beyond UD64::MAX are accepted.
// Book has limited inventory so the result is a partial fill.

#[test]
fn impact_notional_ud128_range_want() {
    let book = book_with_inventory(&[(100, &[10, 20, 30])], &[]);
    // 2^65 ≈ 36_893_488_147_419_103_232, well beyond UD64::MAX
    let large_want: UD128 = udec128!(36893488147419103232);
    let result = book.ask_impact_notional(large_want);
    let (price, filled_size, _vwap, filled_notional) = result.unwrap();
    assert_eq!(price, udec64!(100));
    assert_eq!(filled_size, udec64!(60));
    assert_eq!(filled_notional, udec128!(6000));
}