> For the complete documentation index, see [llms.txt](https://ordiswap.gitbook.io/ordiswap/llms.txt). Markdown versions of documentation pages are available by appending `.md` to page URLs; this page is available as [Markdown](https://ordiswap.gitbook.io/ordiswap/ordiswap-off-chain-engine/protocol-structure/cross-chain-swap-logic.md).

# Cross-Chain Swap Logic

**Import Statements:**

Ordiswap imports multiple modules (`factory`, `orderbook`, `thorswap`) and various utilities and configurations, including constants and functions.

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#### **Order Type Constants:**

Ordiswap defines constants (`ORDER_TYPE_BTC_ETH`, `ORDER_TYPE_ETH_BTC`, `ORDER_TYPE_BRC_ETH`, `ORDER_TYPE_ETH_BRC`) representing different types of bridge orders.

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#### **Send Bitcoin with Data:**

`sendBtcWithData`: Sends Bitcoin with data to a specified recipient address. It retrieves inputs, calculates fees, creates a raw transaction, signs it, and sends it. It supports attaching additional data to the transaction.

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#### **Success and Fail Order Processing:**

`successProcess`: Updates a bridge order with success details and status.

`failProcess`: Updates a bridge order with failure details and status.

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#### **Order Retrieval and Listing:**

`getOrder`: Retrieves a bridge order from the DB collection based on a given filter.

`getOrderList`: Retrieves a list of bridge orders based on specified filter, sort, start, and limit parameters.

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#### **Add Order:**

`addOrder`: Adds a bridge order to the DB collection. It also interacts with Thorswap if the order type is related to BTC-ETH, ETH-BTC, or ETH-BRC.

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#### **BRC-ETH Order Processing:**

`processBrcEthOrder`: Processes a BRC-ETH-related bridge order. It interacts with Ordiswap, obtains Thorswap quotes, and handles Bitcoin transactions with data.

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#### **ETH-BRC Order Processing:**

`processEthBrcOrder`: Processes an ETH-BRC-related bridge order. It interacts with Thorswap, Ordiswap, and handles Bitcoin transactions with data.

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#### **Bridge Order Processing Thread:**

`bridgeThread`: Runs an infinite loop to periodically process bridge orders. It fetches pending bridge orders, processes each order based on its type, and then waits for a specified duration.

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#### **Error Handling:**

Ordiswap includes error handling for various scenarios, logging errors for further analysis.

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#### System Flow:

#### **Order Placement:**

Users can add a bridge order (`addOrder`) with various types, including BTC-ETH, ETH-BTC, BRC-ETH, ETH-BRC. The system checks conditions for each type and may interact with Thorswap or Ordiswap accordingly.

**Order Processing:**

The background thread (`bridgeThread`) continuously processes ordered bridge orders. It interacts with Thorswap, Ordiswap, and handles Bitcoin transactions based on the type of order.

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