Invoice Exchange

Requirements

• Go 1.18 or later

Installation

• Clone the repository
• Run go mod download to download the dependencies
• Run go build to build the binary
• optionally pass -o <binary_name> to specify the name of the binary
• Run ./<binary_name> to start the server.
• You might need to run chmod +x <binary_name> to make the binary executable.
• Alternatively, you can run go run main.go to start the server

Usage

• The server will start on port 8080 by default, it can be changed by setting the SERVE_PORT environment variable.
• If an environment variable TLS is set to true, the server will start with TLS enabled and will look for the following environment variables:
  • CERT_PATH: The path to the certificate file, by default its set to invoiceexchange.local.pem
  • CERT_PRIVATE_KEY: The path to the key file, by default its set to invoiceexchange.local-key.pem
  • The TLS port is set to 443 by default, it can be changed by setting the TLS_PORT environment variable.
• By default, the server runs in dev mode, it can be changed by setting the ENVIRONMENT environment variable to prod.
• By default, the server starts looks for POSTGRES_DSN environment variable to connect to the database.
• In local.yaml the ENT-DRIVER environment variable is set to sqlite to use sqlite as the database driver. If the ent-driver in the yaml or the environment variable ENT_DRIVER is set to pgx, the server will use postgres as the database driver. The sqlite uses postgres dialect so the database can be easily switched.
• If the ENT_DRIVER is set to sqlite, the server will not use the POSTGRES_DSN environment variable to connect to the database.
• The sqlite database starts with some preloaded data for testing purposes. The data is saved in a file called local.db in the root directory of the project. The file can be deleted to start with a fresh database.
• The server uses ent framework for the database layer. The ent schema is defined in ent/schema directory. To install ent follow the instructions here. The ent schema can be generated by running go generate tools.go in the root directory of the project. Alternatively, you can use the ent binary to generate the schema.
• To see the ent schema description run ent describe ./ent/schema in the root directory of the project. go generate tools.go print the describe after generating the schema.
• Alternatively, a generated ent schema describe has been provided at tools/dump_ddl/ENT_DESCRIBE.

Running with Postgres

Please find the initial migration dump located in tools/dump_ddl/initial_dump

• Create a database in postgres.
• Set the POSTGRES_DSN environment variable to your postgres dsn in the format of user=user password=password host=host port=port dbname=dbname sslmode=disable
• Alternatively update the PostgresDSN variable in tools/dump_ddl/main.go and run go run tools/dump_ddl/main.go to print the migration dump, it will output the dump in stdout.
• Run the migration dump in the database to create the tables.
• If running with dev environment, set the ent-driver variable to pgx to use the postgres driver instead of the sqlite driver.
• Alternatively set the ENT_DRIVER environment variable to pgx to use the postgres driver.
• Update the postgres-dsn in local.yaml with the correct values.

Testing

• Run go test ./... to run all unit tests
• Run go test -tags=e2e ./... to run test with all end-to-end scenarios
• Alternatively cd handlers && go test -tags=e2e ./... to run just the end-to-end scenario tests for the handlers

Project structure

• config: Contains the configuration files for the server
• ent: Contains the ent schema and generated ent code
• eventhandler: Contains the event handlers for the server. Currently, it only contains the handler for bid.created event.
• handlers: Contains the HTTP handlers/ controllers for the server
• internal: Contains the internal packages, services, and types
• repos: Contains the repository layer for the server
• router: Contains the router and middleware for the server. The router is built on top of gorilla mux. The routes can be found at router/routes.go. The middlewares can be found inside the router/middleware directory.
• services: Contains the services for the server, the services are responsible for the business logic of the server.
• tools: Contains the tools for the server, currently it only contains the dump_ddl tool to generate the migration dump for the database and the postman collection json for the API.

API

• A postman collection can be found here. The collection contains all the endpoints and examples for the requests and responses.
• Alternatively, you can import the collection to postman from the tools/invoiceexchange.postman_collection.json file in the root directory of the project. The collection is exported with Collection v2.1.

Improvements

• Improve the balance schema and the relation between balance, issuers, and investors. Currently, the balance.entity_id is set to unique which won't allow the issuer or investor to have multiple balance entry, but the edges are O2M.
• Need ledger implementation for the available balance as well, currently the ledger is only implemented for the total balance.
• Properly assert param and returned values in test.
• More end to end scenarios and unit test cases should be tested to ensure that the system is working as expected.
• A better implementation for the eventbus.
• Proper setup and teardown for the end-to-end tests.
• Invoice items are currently not being saved, the invoice items should be saved in the database and the invoice should reference the invoice items.