package web3

import (
	"context"
	"errors"
)

// Pool is the multi-chain RPC client surface. Each chain has one or
// more upstream URLs; Pool.Call selects an upstream, applies
// per-method caching via deps.Base, and meters compute units via
// deps.Commerce.
//
// TODO(bootnode-port): port from bootnode/core/chains/rpc.py — the
// production version maintains per-upstream health, sticky-session
// routing for `eth_getLogs`, and exponential backoff. Prefer
// `luxfi/geth` or `luxfi/ethclient` over upstream go-ethereum.
type Pool interface {
	Call(ctx context.Context, chain string, method string, params any) (any, error)
}

// ErrNoUpstream is returned when no upstream URL is configured for a
// chain.
var ErrNoUpstream = errors.New("web3: no upstream configured for chain")

// NewPool returns a placeholder pool that always errors. Wired by
// superbase once the real implementation lands.
func NewPool(_ map[string][]string) Pool { return &emptyPool{} }

type emptyPool struct{}

func (e *emptyPool) Call(_ context.Context, _ string, _ string, _ any) (any, error) {
	return nil, ErrNoUpstream
}