feat: [Indexer] implemented pg store for indexer (#164)

* feat: indexer fetcher

* feat: indexer refactored

* improved impl

* store modified

* removed doc

* feat: indexer http service

* feat: only applied private http

* lint fixed

* removed unused middleware

* feat: pg implementation for indexer store

* ordering fix

* lint fix and improvements

* added negetive balance check

Author: sadiq1971

pkg/indexer/store/model.go

@@ -0,0 +1,122 @@
+package store
+
+import (
+	"time"
+
+	"github.com/uptrace/bun"
+
+	"github.com/chainsafe/canton-middleware/pkg/indexer"
+)
+
+// EventDao maps to the 'indexer_events' table.
+// ContractID is the idempotency key — one row per TokenTransferEvent contract.
+type EventDao struct {
+	bun.BaseModel   `bun:"table:indexer_events"`
+	ContractID      string    `bun:",pk,type:varchar(255)"`
+	InstrumentID    string    `bun:",notnull,type:varchar(255)"`
+	InstrumentAdmin string    `bun:",notnull,type:varchar(255)"`
+	Issuer          string    `bun:",notnull,type:varchar(255)"`
+	EventType       string    `bun:",notnull,type:varchar(20)"`
+	Amount          string    `bun:",notnull,type:text"`
+	FromPartyID     *string   `bun:",type:varchar(255)"`
+	ToPartyID       *string   `bun:",type:varchar(255)"`
+	ExternalTxID    *string   `bun:",type:varchar(255)"`
+	ExternalAddress *string   `bun:",type:varchar(255)"`
+	Fingerprint     *string   `bun:",type:varchar(255)"`
+	TxID            string    `bun:",notnull,type:varchar(255)"`
+	LedgerOffset    int64     `bun:",notnull"`
+	Timestamp       time.Time `bun:",notnull"`
+	EffectiveTime   time.Time `bun:",notnull"`
+}
+
+// TokenDao maps to the 'indexer_tokens' table.
+// The composite key (InstrumentAdmin, InstrumentID) uniquely identifies a token.
+type TokenDao struct {
+	bun.BaseModel   `bun:"table:indexer_tokens"`
+	InstrumentAdmin string    `bun:",pk,type:varchar(255)"`
+	InstrumentID    string    `bun:",pk,type:varchar(255)"`
+	Issuer          string    `bun:",notnull,type:varchar(255)"`
+	TotalSupply     string    `bun:",notnull,type:text,default:'0'"`
+	HolderCount     int64     `bun:",notnull,default:0"`
+	FirstSeenOffset int64     `bun:",notnull"`
+	FirstSeenAt     time.Time `bun:",notnull"`
+}
+
+// BalanceDao maps to the 'indexer_balances' table.
+// The composite key (PartyID, InstrumentAdmin, InstrumentID) is unique per holding.
+type BalanceDao struct {
+	bun.BaseModel   `bun:"table:indexer_balances"`
+	PartyID         string `bun:",pk,type:varchar(255)"`
+	InstrumentAdmin string `bun:",pk,type:varchar(255)"`
+	InstrumentID    string `bun:",pk,type:varchar(255)"`
+	Amount          string `bun:",notnull,type:text"`
+}
+
+// OffsetDao maps to the 'indexer_offsets' table.
+// A single row (ID=1) holds the latest persisted ledger offset.
+type OffsetDao struct {
+	bun.BaseModel `bun:"table:indexer_offsets"`
+	ID            int   `bun:",pk,default:1"`
+	LedgerOffset  int64 `bun:",notnull,default:0"`
+}
+
+func toEventDao(e *indexer.ParsedEvent) *EventDao {
+	return &EventDao{
+		ContractID:      e.ContractID,
+		InstrumentID:    e.InstrumentID,
+		InstrumentAdmin: e.InstrumentAdmin,
+		Issuer:          e.Issuer,
+		EventType:       string(e.EventType),
+		Amount:          e.Amount,
+		FromPartyID:     e.FromPartyID,
+		ToPartyID:       e.ToPartyID,
+		ExternalTxID:    e.ExternalTxID,
+		ExternalAddress: e.ExternalAddress,
+		Fingerprint:     e.Fingerprint,
+		TxID:            e.TxID,
+		LedgerOffset:    e.LedgerOffset,
+		Timestamp:       e.Timestamp,
+		EffectiveTime:   e.EffectiveTime,
+	}
+}
+
+func fromEventDao(d *EventDao) *indexer.ParsedEvent {
+	return &indexer.ParsedEvent{
+		ContractID:      d.ContractID,
+		InstrumentID:    d.InstrumentID,
+		InstrumentAdmin: d.InstrumentAdmin,
+		Issuer:          d.Issuer,
+		EventType:       indexer.EventType(d.EventType),
+		Amount:          d.Amount,
+		FromPartyID:     d.FromPartyID,
+		ToPartyID:       d.ToPartyID,
+		ExternalTxID:    d.ExternalTxID,
+		ExternalAddress: d.ExternalAddress,
+		Fingerprint:     d.Fingerprint,
+		TxID:            d.TxID,
+		LedgerOffset:    d.LedgerOffset,
+		Timestamp:       d.Timestamp,
+		EffectiveTime:   d.EffectiveTime,
+	}
+}
+
+func fromTokenDao(d *TokenDao) *indexer.Token {
+	return &indexer.Token{
+		InstrumentAdmin: d.InstrumentAdmin,
+		InstrumentID:    d.InstrumentID,
+		Issuer:          d.Issuer,
+		TotalSupply:     d.TotalSupply,
+		HolderCount:     d.HolderCount,
+		FirstSeenOffset: d.FirstSeenOffset,
+		FirstSeenAt:     d.FirstSeenAt,
+	}
+}
+
+func fromBalanceDao(d *BalanceDao) *indexer.Balance {
+	return &indexer.Balance{
+		PartyID:         d.PartyID,
+		InstrumentAdmin: d.InstrumentAdmin,
+		InstrumentID:    d.InstrumentID,
+		Amount:          d.Amount,
+	}
+}