// SPDX-FileCopyrightText: © 2026 LEDGER SAS
// SPDX-License-Identifier: Apache-2.0

import type { StellarContext } from '../config'
import type { BlockInfo } from '@ledgerhq/coin-module-framework/api/index'
import { fetchLedgerRecord } from '../network'

/**
 * Returns lightweight metadata for a Stellar closed ledger at the given sequence.
 *
 * Fetches the ledger once. When `height > 1` and Horizon provides `prev_hash`,
 * `BlockInfo.parent` is derived without a second request; otherwise the parent
 * ledger is loaded explicitly. Genesis ledger sequence 1 has no parent.
 */
export async function getBlockInfo(context: StellarContext, height: number): Promise<BlockInfo> {
  if (!Number.isSafeInteger(height) || height <= 0) {
    throw new Error(`getBlockInfo: height must be a positive integer, got ${height}`)
  }

  const config = await context.config()
  const ledger = await fetchLedgerRecord(config, height)

  const info: BlockInfo = {
    height: ledger.sequence,
    hash: ledger.hash,
    time: new Date(ledger.closed_at),
  }

  let parent: BlockInfo['parent']
  if (height > 1) {
    const prevHash =
      'prev_hash' in ledger && typeof ledger.prev_hash === 'string' ? ledger.prev_hash : undefined
    if (prevHash) {
      parent = { height: height - 1, hash: prevHash }
    } else {
      const parentLedger = await fetchLedgerRecord(config, height - 1)
      parent = { height: parentLedger.sequence, hash: parentLedger.hash }
    }
    info.parent = parent
  }

  return info
}