status-im/status-go

package subscriptions

import (
    "fmt"

    "github.com/status-im/status-go/rpc"
)

type ethFilter struct {
    id        string
    rpcClient *rpc.Client
}

func installEthFilter(rpcClient *rpc.Client, method string, args []interface{}) (*ethFilter, error) {

    if err := validateEthMethod(method); err != nil {
        return nil, err
    }

    var result string

    err := rpcClient.Call(&result, rpcClient.UpstreamChainID, method, args...)

    if err != nil {
        return nil, err
    }

    filter := &ethFilter{
        id:        result,
        rpcClient: rpcClient,
    }

    return filter, nil

}

func (ef *ethFilter) getID() string {
    return ef.id
}

func (ef *ethFilter) getChanges() ([]interface{}, error) {
    var result []interface{}

    err := ef.rpcClient.Call(&result, ef.rpcClient.UpstreamChainID, "eth_getFilterChanges", ef.getID())

    return result, err
}

func (ef *ethFilter) uninstall() error {
    return ef.rpcClient.Call(nil, ef.rpcClient.UpstreamChainID, "eth_uninstallFilter", ef.getID())
}

func validateEthMethod(method string) error {
    for _, allowedMethod := range []string{
        "eth_newFilter",
        "eth_newBlockFilter",
        "eth_newPendingTransactionFilter",
    } {
        if method == allowedMethod {
            return nil
        }
    }

    return fmt.Errorf("unexpected filter method: %s", method)
}