import type * as Chain from './Chain.js'

/** A token accepted or returned by a funding provider. */
export type Token = {
  /** Chain-specific token metadata keyed by CAIP-2 chain id. */
  chains: Partial<Record<Chain.Id, ChainConfig>>
  /** Monetary denomination represented by the token. */
  currency: string
  /** Human-readable token name. */
  name: string
  /** Stable token segment used in quote identifiers. */
  slug: string
  /** Short token ticker symbol. */
  symbol: string
}

/** Chain-specific token metadata. */
export type ChainConfig = {
  /** Contract address, mint, or issuer address on the chain. */
  address: string
  /** Number of decimal places used by the token on the chain. */
  decimals: number
  /** Chain-specific token name override. */
  name?: string | undefined
  /** Token standard on the chain. */
  standard: string
}

/** A token resolved to one funding chain. */
export type Resolved = Omit<Token, 'chains'> &
  Omit<ChainConfig, 'name'> & {
    /** Chain where the token exists. */
    chain: Chain.Chain
    /** Human-readable token name for this chain. */
    name: string
  }

/** Creates a canonical funding token. */
export function from<const token extends Token>(options: token): token {
  return options
}

/** Resolves a funding token to its metadata on one chain. */
export function resolve(token: Token, chain: Chain.Chain): Resolved {
  const config = token.chains[chain.id]
  if (!config) throw new MissingChainError()
  const { chains: _chains, ...metadata } = token
  return {
    ...metadata,
    ...config,
    chain,
    name: config.name ?? token.name,
  }
}

/** Error thrown when a token is not configured for a selected chain. */
export class MissingChainError extends Error {
  override name = 'Funding.Token.MissingChainError'
}