add (feat) pagination helpers and token endpoint

- see docs for pagination api usage
- added control for syncer/api goroutines

cmd/init.go

@@ -33,6 +33,12 @@ type config struct {
 		TokenRegistry   string `koanf:"index"`
 		BalanceResolver string `koanf:"balances_resolver"`
 	}
+	Syncer struct {
+		Enabled bool `koanf:"enabled"`
+	}
+	Api struct {
+		Enabled bool `koan:"enabled"`
+	}
 	Syncers map[string]string `koanf:"syncers"`
 }
 

cmd/main.go

@@ -70,20 +70,25 @@ func main() {
 		log.Fatal().Err(err).Msg("could not bootstrap scheduler")
 	}
 
+	processor, mux := bootstrapProcessor(rClient)
+
+	if conf.Syncer.Enabled {
 		go func() {
 			if err := scheduler.Run(); err != nil {
 				log.Fatal().Err(err).Msg("could not start scheduler")
 			}
 		}()
 
-	processor, mux := bootstrapProcessor(rClient)
 		go func() {
 			if err := processor.Run(mux); err != nil {
 				log.Fatal().Err(err).Msg("failed to start job processor")
 			}
 		}()
+	}
 
 	server := initHTTPServer()
+
+	if conf.Api.Enabled {
 		go func() {
 			if err := server.Start(conf.Server.Address); err != nil {
 				if strings.Contains(err.Error(), "Server closed") {
@@ -93,6 +98,7 @@ func main() {
 				}
 			}
 		}()
+	}
 
 	sigs := make(chan os.Signal, 1)
 	signal.Notify(sigs, unix.SIGTERM, unix.SIGINT, unix.SIGTSTP)

config.toml

@@ -16,6 +16,12 @@ index = "0x5A1EB529438D8b3cA943A45a48744f4c73d1f098"
 balances_resolver = "0xb9e215B789e9Ec6643Ba4ff7b98EA219F38c6fE5"
 rpc   = "http://127.0.0.1:8545"
 
+[syncer]
+enabled = true
+
+[api]
+enabled = true
+
 [syncers]
 cache = "@every 20s"
 ussd  = "@every 30s"

internal/public/api.go

@@ -27,5 +27,9 @@ func InitPublicApi(e *echo.Echo, db *pgxpool.Pool, batchBalance *batch_balance.B
 		}
 	})
 
+	// TODO: paginate schema validation
+
 	g.GET("/balances/:address", handleBalancesQuery)
+	g.GET("/tokens-count", handleTokensCountQuery)
+	g.GET("/tokens", handleTokenListQuery)
 }

internal/public/tokens.go

@@ -0,0 +1,65 @@
+package public
+
+import (
+	"cic-dw/pkg/pagination"
+	"context"
+	"net/http"
+
+	"github.com/georgysavva/scany/pgxscan"
+	"github.com/labstack/echo/v4"
+)
+
+type tokensRes struct {
+	Id           int    `db:"id" json:"id"`
+	TokenSymbol  string `db:"token_symbol" json:"token_symbol"`
+	TokenName    string `db:"token_name" json:"token_name"`
+	TokenAddress string `db:"token_address" json:"token_addres"`
+}
+
+type tokenCountRes struct {
+	Count int `db:"count" json:"count"`
+}
+
+func handleTokenListQuery(c echo.Context) error {
+	var (
+		api = c.Get("api").(*api)
+		pg  = pagination.GetPagination(c.QueryParams())
+		res []tokensRes
+		q   string
+	)
+
+	if pg.Forward {
+		q = api.q["list-tokens-fwd"]
+	} else {
+		q = api.q["list-tokens-bkwd"]
+	}
+
+	rows, err := api.db.Query(context.Background(), q, pg.Cursor, pg.PerPage)
+	if err != nil {
+		return err
+	}
+
+	if err := pgxscan.ScanAll(&res, rows); err != nil {
+		return err
+	}
+
+	return c.JSON(http.StatusOK, res)
+}
+
+func handleTokensCountQuery(c echo.Context) error {
+	var (
+		api = c.Get("api").(*api)
+		res tokenCountRes
+	)
+
+	rows, err := api.db.Query(context.Background(), api.q["tokens-count"])
+	if err != nil {
+		return err
+	}
+
+	if err := pgxscan.ScanOne(&res, rows); err != nil {
+		return err
+	}
+
+	return c.JSON(http.StatusOK, res)
+}

pkg/pagination/pagination.go

@@ -0,0 +1,34 @@
+package pagination
+
+import (
+	"net/url"
+	"strconv"
+)
+
+type Pagination struct {
+	PerPage int
+	Cursor  int
+	Forward bool
+}
+
+func GetPagination(q url.Values) Pagination {
+	var (
+		pp, _      = strconv.Atoi(q.Get("per_page"))
+		cursor, _  = strconv.Atoi(q.Get("cursor"))
+		forward, _ = strconv.ParseBool(q.Get("forward"))
+	)
+
+	if pp > 100 {
+		pp = 100
+	}
+
+	if !forward && cursor < 1 {
+		cursor = 1
+	}
+
+	return Pagination{
+		PerPage: pp,
+		Cursor:  cursor,
+		Forward: forward,
+	}
+}

queries/public.sql

@@ -4,3 +4,16 @@ SELECT DISTINCT tokens.token_symbol, tokens.token_address FROM transactions
 INNER JOIN tokens on transactions.token_address = tokens.token_address
 WHERE transactions.sender_address = $1
 OR transactions.recipient_address = $1;
+
+-- Bidirectional cursor pagianators
+-- name: list-tokens-fwd
+SELECT tokens.id, tokens.token_address, tokens.token_name, tokens.token_symbol FROM tokens
+WHERE tokens.id > $1 ORDER BY tokens.id ASC LIMIT $2;
+
+-- name: list-tokens-bkwd
+SELECT tokens.id, tokens.token_address, tokens.token_name, tokens.token_symbol FROM tokens
+WHERE tokens.id < $1 ORDER BY tokens.id ASC LIMIT $2;
+
+-- name: tokens-count
+-- Return total record count from individual i= tables/views
+SELECT COUNT(*) FROM tokens;