typedef opaque UpgradeType<128>;

enum StellarValueType
{
    STELLAR_VALUE_BASIC = 0,
    STELLAR_VALUE_SIGNED = 1
};

struct LedgerCloseValueSignature
{
    NodeID nodeID;       // which node introduced the value
    Signature signature; // nodeID's signature
};

/* StellarValue is the value used by SCP to reach consensus on a given ledger
 */
union StellarValueExt switch (StellarValueType v)
{
case STELLAR_VALUE_BASIC:
    void;
case STELLAR_VALUE_SIGNED:
    LedgerCloseValueSignature lcValueSignature;
};

struct StellarValue
{
    Hash txSetHash;      // transaction set to apply to previous ledger
    TimePoint closeTime; // network close time

    // upgrades to apply to the previous ledger (usually empty)
    // this is a vector of encoded 'LedgerUpgrade' so that nodes can drop
    // unknown steps during consensus if needed.
    // see notes below on 'LedgerUpgrade' for more detail
    // max size is dictated by number of upgrade types (+ room for future)
    UpgradeType upgrades<6>;

    // reserved for future use
    StellarValueExt ext;
};

/* The LedgerHeader is the highest level structure representing the
 * state of a ledger, cryptographically linked to previous ledgers.
 */
union LedgerHeaderExt switch (int v)
{
case 0:
    void;
};

struct LedgerHeader
{
    uint32 ledgerVersion;    // the protocol version of the ledger
    Hash previousLedgerHash; // hash of the previous ledger header
    StellarValue scpValue;   // what consensus agreed to
    Hash txSetResultHash;    // the TransactionResultSet that led to this ledger
    Hash bucketListHash;     // hash of the ledger state

    uint32 ledgerSeq; // sequence number of this ledger

    int64 totalCoins; // total number of stroops in existence.
                      // 10,000,000 stroops in 1 XLM

    int64 feePool;       // fees burned since last inflation run
    uint32 inflationSeq; // inflation sequence number

    uint64 idPool; // last used global ID, used for generating objects

    uint32 baseFee;     // base fee per operation in stroops
    uint32 baseReserve; // account base reserve in stroops

    uint32 maxTxSetSize; // maximum size a transaction set can be

    Hash skipList[4]; // hashes of ledgers in the past. allows you to jump back
                      // in time without walking the chain back ledger by ledger
                      // each slot contains the oldest ledger that is mod of
                      // either 50  5000  50000 or 500000 depending on index
                      // skipList[0] mod(50), skipList[1] mod(5000), etc

    // reserved for future use
    LedgerHeaderExt ext;
};

/* Ledger upgrades
note that the `upgrades` field from StellarValue is normalized such that
it only contains one entry per LedgerUpgradeType, and entries are sorted
in ascending order
*/
enum LedgerUpgradeType
{
    LEDGER_UPGRADE_VERSION = 1,
    LEDGER_UPGRADE_BASE_FEE = 2,
    LEDGER_UPGRADE_MAX_TX_SET_SIZE = 3,
    LEDGER_UPGRADE_BASE_RESERVE = 4
};

union LedgerUpgrade switch (LedgerUpgradeType type)
{
case LEDGER_UPGRADE_VERSION:
    uint32 newLedgerVersion; // update ledgerVersion
case LEDGER_UPGRADE_BASE_FEE:
    uint32 newBaseFee; // update baseFee
case LEDGER_UPGRADE_MAX_TX_SET_SIZE:
    uint32 newMaxTxSetSize; // update maxTxSetSize
case LEDGER_UPGRADE_BASE_RESERVE:
    uint32 newBaseReserve; // update baseReserve
};

/* Entries used to define the bucket list */
struct LedgerKeyAccount
{
    AccountID accountID;
};

struct LedgerKeyTrustline
{
    AccountID accountID;
    Asset asset;
};

struct LedgerKeyOffer
{
    AccountID sellerID;
    int64 offerID;
};

struct LedgerKeyData
{
    AccountID accountID;
    string64 dataName;
};

union LedgerKey switch (LedgerEntryType type)
{
case ACCOUNT:
     LedgerKeyAccount account;

case TRUSTLINE:
     LedgerKeyTrustline trustLine;

case OFFER:
     LedgerKeyOffer offer;

case DATA:
     LedgerKeyData data;
};

enum BucketEntryType
{
    METAENTRY =
        -1, // At-and-after protocol 11: bucket metadata, should come first.
    LIVEENTRY = 0, // Before protocol 11: created-or-updated;
                   // At-and-after protocol 11: only updated.
    DEADENTRY = 1,
    INITENTRY = 2 // At-and-after protocol 11: only created.
};

union BucketMetadataExt switch (int v)
{
case 0:
    void;
};

struct BucketMetadata
{
    // Indicates the protocol version used to create / merge this bucket.
    uint32 ledgerVersion;

    // reserved for future use
    BucketMetadataExt ext;
};

union BucketEntry switch (BucketEntryType type)
{
case LIVEENTRY:
case INITENTRY:
    LedgerEntry liveEntry;

case DEADENTRY:
    LedgerKey deadEntry;
case METAENTRY:
    BucketMetadata metaEntry;
};

// Transaction sets are the unit used by SCP to decide on transitions
// between ledgers
struct TransactionSet
{
    Hash previousLedgerHash;
    TransactionEnvelope txs<>;
};

struct TransactionResultPair
{
    Hash transactionHash;
    TransactionResult result; // result for the transaction
};

// TransactionResultSet is used to recover results between ledgers
struct TransactionResultSet
{
    TransactionResultPair results<>;
};

// Entries below are used in the historical subsystem

union TransactionHistoryEntryExt switch (int v)
{
case 0:
    void;
};

struct TransactionHistoryEntry
{
    uint32 ledgerSeq;
    TransactionSet txSet;

    // reserved for future use
    TransactionHistoryEntryExt ext;
};

union TransactionHistoryResultEntryExt switch (int v)
{
case 0:
    void;
};

struct TransactionHistoryResultEntry
{
    uint32 ledgerSeq;
    TransactionResultSet txResultSet;

    // reserved for future use
    TransactionHistoryResultEntryExt ext;
};

union LedgerHeaderHistoryEntryExt switch (int v)
{
case 0:
    void;
};

struct LedgerHeaderHistoryEntry
{
    Hash hash;
    LedgerHeader header;

    // reserved for future use
    LedgerHeaderHistoryEntryExt ext;
};

// historical SCP messages

struct LedgerSCPMessages
{
    uint32 ledgerSeq;
    SCPEnvelope messages<>;
};

// note: ledgerMessages may refer to any quorumSets encountered
// in the file so far, not just the one from this entry
struct SCPHistoryEntryV0
{
    SCPQuorumSet quorumSets<>; // additional quorum sets used by ledgerMessages
    LedgerSCPMessages ledgerMessages;
};

// SCP history file is an array of these
union SCPHistoryEntry switch (int v)
{
case 0:
    SCPHistoryEntryV0 v0;
};

// represents the meta in the transaction table history

// STATE is emitted every time a ledger entry is modified/deleted
// and the entry was not already modified in the current ledger

enum LedgerEntryChangeType
{
    LEDGER_ENTRY_CREATED = 0, // entry was added to the ledger
    LEDGER_ENTRY_UPDATED = 1, // entry was modified in the ledger
    LEDGER_ENTRY_REMOVED = 2, // entry was removed from the ledger
    LEDGER_ENTRY_STATE = 3    // value of the entry
};

union LedgerEntryChange switch (LedgerEntryChangeType type)
{
case LEDGER_ENTRY_CREATED:
    LedgerEntry created;
case LEDGER_ENTRY_UPDATED:
    LedgerEntry updated;
case LEDGER_ENTRY_REMOVED:
    LedgerKey removed;
case LEDGER_ENTRY_STATE:
    LedgerEntry state;
};

typedef LedgerEntryChange LedgerEntryChanges<>;

struct OperationMeta
{
    LedgerEntryChanges changes;
};

struct TransactionMetaV1
{
    LedgerEntryChanges txChanges; // tx level changes if any
    OperationMeta operations<>;   // meta for each operation
};

// this is the meta produced when applying transactions
// it does not include pre-apply updates such as fees
union TransactionMeta switch (int v)
{
case 0:
    OperationMeta operations<>;
case 1:
    TransactionMetaV1 v1;
};