package main

import (
    "context"
    "fmt"
    
    eth2client "github.com/attestantio/go-eth2-client"
    "github.com/attestantio/go-eth2-client/api"
    "github.com/attestantio/go-eth2-client/http"
    "github.com/rs/zerolog"
)

func main() {
    // Provide a cancellable context to the creation function.
    ctx, cancel := context.WithCancel(context.Background())
    client, err := http.New(ctx,
        // WithAddress supplies the address of the beacon node, as a URL.
        http.WithAddress("http://localhost:5052/"),
        // LogLevel supplies the level of logging to carry out.
        http.WithLogLevel(zerolog.WarnLevel),
    )
    if err != nil {
        panic(err)
    }
    
    fmt.Printf("Connected to %s\n", client.Name())
    
    // Client functions have their own interfaces.  Not all functions are
    // supported by all clients, so checks should be made for each function when
    // casting the service to the relevant interface.
    if provider, isProvider := client.(eth2client.GenesisProvider); isProvider {
        genesisResponse, err := provider.Genesis(ctx)
        if err != nil {
            // Errors may be API errors, in which case they will have more detail
            // about the failure.
            var apiErr *api.Error
            if errors.As(err, &apiErr) {
                switch apiErr.StatusCode {
                  case 404:
                    panic("genesis not found")
                  case 503:
                    panic("node is syncing")
                }
            }
            panic(err)
        }
        fmt.Printf("Genesis time is %v\n", genesisResponse.Data.GenesisTime)
    }

    // You can also access the struct directly if required.
    httpClient := client.(*http.Service)
    genesisResponse, err := httpClient.Genesis(ctx)
    if err != nil {
        panic(err)
    }
    fmt.Printf("Genesis validators root is %s\n", genesisResponse.Data.GenesisValidatorsRoot)

    // Cancelling the context passed to New() frees up resources held by the
    // client, closes connections, clears handlers, etc.
    cancel()
}