docs: update README.md to enhance project description and usage instructions

Author: cqlyj

README.md

@@ -1,17 +1,208 @@
-What this project does:
+## About the Project
 
-1. Users use their account address and select the supported ways to make payments and the supported chains to make payments.
-2. Our contract will monitor the user's account after some time and check if the user has enough balance to make the payment.
-3. If the user has enough balance, the contract will take some amount of the user's balance and send it to the recipient's address.
-4. If the user does not have enough balance, the contract will rather check the second chain where user has enough balance and send the payment from that chain.
-5. If the user does not have enough balance in any of the chains, the contract will then notify the user about the insufficient balance.
+ChainSync is a subscription system where user can pay the subscription fee on different chains with the help of Chainlink CCIP.
 
-This is like a subscription service where the user can select the supported chains and supported ways to make payments and the contract will automatically make the payment from the user's account to the recipient's account.
+The user can decide which chain to pay the subscription fee on. => Primary payment chain and optional payment chain(s).
 
-- TBH, I think if there is not enough token on the optional chain, it will revert, but I just want to show the integration of those chainlink techniques.
+- if the user pays the subscription fee on the primary chain, which is where the `Subscription` contract is deployed, it will be simple payment process.
+- if the user pays the subscription fee on the optional chain, the payment process will be a bit complex. As shown below:
 
----
+### Process of optional chain payment:
+
+Role of each contract in the process:
 
-## Process of optional chain payment:
+- `Subscription` contract: The contract where the user subscribes to the service.
+- `CheckBalance` contract: The contract which send an API request to the `Blockscout` service to check the balance of the user's token on the optional chain.
+- `Sender` contract: The contract which sends the cross-chain message to the `Receiver` contract on the optional chain.
+- `Receiver` contract: The contract which receives the cross-chain message from the `Sender` contract and do the actual transfer process.
+- `Relayer` contract: The contract which listens for `MessageReceived` event from the `Receiver` contract and sends another cross-chain message back to the `Subscription` contract to update the user's subscription status.
 
 ![Process of optional chain payment](img/optional_chain_payment_process.svg)
+
+---
+
+## Built With
+
+- Solidity
+- OpenZeppelin
+- Foundry
+- Blockscout
+- Chainlink (CCIP, Functions, Automation)
+
+## Getting Started
+
+### Prerequisites
+
+- [git](https://git-scm.com/book/en/v2/Getting-Started-Installing-Git)
+  - You'll know you did it right if you can run `git --version` and you see a response like `git version x.x.x`
+- [foundry](https://getfoundry.sh/)
+  - You'll know you did it right if you can run `forge --version` and you see a response like `forge 0.2.0 (816e00b 2023-03-16T00:05:26.396218Z)`
+
+### Quickstart
+
+```
+git clone https://github.com/cqlyj/ChainSync.git
+cd ChainSync
+make
+```
+
+## Usage
+
+### Deployment sequence
+
+1. First set up your environment variables in the `.env` file.
+
+```
+cp .env.example .env
+```
+
+2. In `Makefile`, update the `--account burner --sender 0xFB6a372F2F51a002b390D18693075157A459641F` to your own account.
+
+```
+*** --account <your-account-name> --sender <your-account-address> ***
+```
+
+3. In the `Subscription.sol` contract, update the `AMOY_SUBSCRIPTION_ID` variable to your own subscription ID of Chainlink functions. Also update those variables that are related to your own values, you can search those by inputting `@notice update` and update those values.
+
+4. Follow the sequence below to deploy the contracts:
+
+```
+
+make deploy-sender
+make deploy-checkBalance
+make deploy-receiver
+make deploy-subscription
+make deploy-relayer
+
+```
+
+### Interacting with the contracts
+
+Before interacting with the contracts, update those variables that are related to your own values in the script and then run the following commands:
+
+```
+make add-consumer
+make add-linkTokenToReceiver
+make add-linkTokenToRelayer
+make add-linkTokenToSender
+make approve-receiverToSpendCCIPBNM
+make transfer-ownershipToSubscription
+make get-signedMessage
+```
+
+Grab the signedMessage and update this in the `script/PaySubscriptionFeeForOptionalChain` contract.
+Set up your Chainlink Automation services and after everything is set up, run the following command:
+
+```
+make pay-subscriptionFeeforOptionalChain
+```
+
+You now have successfully paid the subscription fee on the optional chain.
+
+## Testing
+
+```
+forge test
+```
+
+## Test Coverage
+
+```
+forge coverage
+```
+
+and for coverage based testing:
+
+```
+forge coverage --report debug
+```
+
+## Static Analysis
+
+### Slither
+
+```
+make slither
+```
+
+### Aderyn
+
+```
+make aderyn
+```
+
+## How to Contribute
+
+We welcome contributions to ChainSync! Here's how you can help:
+
+### Types of Contributions
+
+- **Bug Reports**: Open an issue describing the bug, including steps to reproduce, expected behavior, and actual behavior
+- **Feature Requests**: Submit an issue describing the new feature and its potential benefits
+- **Code Contributions**: Submit pull requests for bug fixes or new features
+- **Documentation**: Help improve or translate our documentation
+- **Testing**: Add more test cases or help identify test coverage gaps
+
+### Development Process
+
+1. Fork the repository and create your branch from `main`:
+
+   ```
+   git checkout -b feature/your-feature-name
+   ```
+
+2. If you've added code, add tests that cover your changes:
+
+   ```
+   forge test
+   ```
+
+3. Ensure your code follows the project's style guidelines:
+
+   ```
+   make slither
+   make aderyn
+   ```
+
+4. Make sure all tests pass:
+
+   ```
+   forge coverage
+   ```
+
+5. Update the documentation if necessary
+
+### Pull Request Process
+
+1. Update the README.md with details of changes if applicable
+2. Follow the existing code style and formatting
+3. Include comments in your code where necessary
+4. Add or update tests for any new functionality
+5. Reference any relevant issues in your PR description
+6. The PR must pass all CI checks and receive approval from a maintainer
+
+### Commit Guidelines
+
+- Use clear and meaningful commit messages
+- Reference issue numbers in commit messages when applicable
+- Keep commits focused on single changes
+- Use present tense ("Add feature" not "Added feature")
+
+### Code of Conduct
+
+- Be respectful and inclusive in your interactions
+- Focus on constructive feedback
+- Help maintain a positive environment for all contributors
+
+### Questions or Need Help?
+
+Feel free to reach out if you have questions or need guidance:
+
+- Open a GitHub issue for project-related questions
+- Contact Luo Yingjie at [[email protected]]([email protected]) for other inquiries
+
+Your contributions help make ChainSync better for everyone. Thank you for your interest in contributing!
+
+## License
+
+This project is licensed under the MIT License - see the [LICENSE](LICENSE) file for details.