import type { Account } from '../../accounts/types.js'
import type { Client } from '../../clients/createClient.js'
import type { Transport } from '../../clients/transports/createTransport.js'
import {
  BlockNotFoundError,
  type BlockNotFoundErrorType,
} from '../../errors/block.js'
import type { ErrorType } from '../../errors/utils.js'
import type { BlockTag } from '../../types/block.js'
import type { Chain } from '../../types/chain.js'
import type { Hash } from '../../types/misc.js'
import type { RpcBlock } from '../../types/rpc.js'
import type { RequestErrorType } from '../../utils/buildRequest.js'
import {
  type NumberToHexErrorType,
  numberToHex,
} from '../../utils/encoding/toHex.js'
import {
  type FormattedBlock,
  formatBlock,
} from '../../utils/formatters/block.js'

export type GetBlockParameters<
  TIncludeTransactions extends boolean = false,
  TBlockTag extends BlockTag = 'latest',
> = {
  /** Whether or not to include transaction data in the response. */
  includeTransactions?: TIncludeTransactions
} & (
  | {
      /** Hash of the block. */
      blockHash?: Hash
      blockNumber?: never
      blockTag?: never
    }
  | {
      blockHash?: never
      /** The block number. */
      blockNumber?: bigint
      blockTag?: never
    }
  | {
      blockHash?: never
      blockNumber?: never
      /**
       * The block tag.
       * @default 'latest'
       */
      blockTag?: TBlockTag | BlockTag
    }
)

export type GetBlockReturnType<
  TChain extends Chain | undefined = Chain | undefined,
  TIncludeTransactions extends boolean = false,
  TBlockTag extends BlockTag = 'latest',
> = FormattedBlock<TChain, TIncludeTransactions, TBlockTag>

export type GetBlockErrorType =
  | BlockNotFoundErrorType
  | NumberToHexErrorType
  | RequestErrorType
  | ErrorType

/**
 * Returns information about a block at a block number, hash, or tag.
 *
 * - Docs: https://viem.sh/docs/actions/public/getBlock.html
 * - Examples: https://stackblitz.com/github/wagmi-dev/viem/tree/main/examples/blocks/fetching-blocks
 * - JSON-RPC Methods:
 *   - Calls [`eth_getBlockByNumber`](https://ethereum.org/en/developers/docs/apis/json-rpc/#eth_getblockbynumber) for `blockNumber` & `blockTag`.
 *   - Calls [`eth_getBlockByHash`](https://ethereum.org/en/developers/docs/apis/json-rpc/#eth_getblockbyhash) for `blockHash`.
 *
 * @param client - Client to use
 * @param parameters - {@link GetBlockParameters}
 * @returns Information about the block. {@link GetBlockReturnType}
 *
 * @example
 * import { createPublicClient, http } from 'viem'
 * import { mainnet } from 'viem/chains'
 * import { getBlock } from 'viem/public'
 *
 * const client = createPublicClient({
 *   chain: mainnet,
 *   transport: http(),
 * })
 * const block = await getBlock(client)
 */
export async function getBlock<
  TChain extends Chain | undefined,
  TAccount extends Account | undefined,
  TIncludeTransactions extends boolean = false,
  TBlockTag extends BlockTag = 'latest',
>(
  client: Client<Transport, TChain, TAccount>,
  {
    blockHash,
    blockNumber,
    blockTag: blockTag_,
    includeTransactions: includeTransactions_,
  }: GetBlockParameters<TIncludeTransactions, TBlockTag> = {},
): Promise<GetBlockReturnType<TChain, TIncludeTransactions, TBlockTag>> {
  const blockTag = blockTag_ ?? 'latest'
  const includeTransactions = includeTransactions_ ?? false

  const blockNumberHex =
    blockNumber !== undefined ? numberToHex(blockNumber) : undefined

  let block: RpcBlock | null = null
  if (blockHash) {
    block = await client.request({
      method: 'eth_getBlockByHash',
      params: [blockHash, includeTransactions],
    })
  } else {
    block = await client.request({
      method: 'eth_getBlockByNumber',
      params: [blockNumberHex || blockTag, includeTransactions],
    })
  }

  if (!block) throw new BlockNotFoundError({ blockHash, blockNumber })

  const format = client.chain?.formatters?.block?.format || formatBlock
  return format(block)
}