feat: improve block parsing starting height calculations (#72)

## Description
Fixes [BDU-489](https://forbole.atlassian.net/browse/BDU-489)
## Checklist
- [x] Targeted PR against correct branch.
- [x] Linked to Github issue with discussion and accepted design OR link to spec that describes this work.
- [ ] Wrote unit tests.  
- [x] Re-reviewed `Files changed` in the Github PR explorer.

CHANGELOG.md

@@ -1,6 +1,7 @@
 ## Unreleased
 ### Changes
 - ([\#71](https://github.com/forbole/juno/pull/71)) Retry RPC client connection upon failure instead of panic
+- ([\#72](https://github.com/forbole/juno/pull/72)) Updated missing blocks parsing 
 
 ## v3.3.0
 ### Changes

cmd/parse/blocks/blocks.go

@@ -4,6 +4,7 @@ import (
 	"fmt"
 
 	parsecmdtypes "github.com/forbole/juno/v3/cmd/parse/types"
+	"github.com/forbole/juno/v3/types/utils"
 
 	"github.com/rs/zerolog/log"
 
@@ -44,8 +45,15 @@ will be replaced with the data downloaded from the node.
 			end, _ := cmd.Flags().GetInt64(flagEnd)
 			force, _ := cmd.Flags().GetBool(flagForce)
 
-			// Get the start height, default to the config's height; use flagStart if set
-			startHeight := config.Cfg.Parser.StartHeight
+			lastDbBlockHeight, err := parseCtx.Database.GetLastBlockHeight()
+			if err != nil {
+				return err
+			}
+
+			// Compare start height from config file and last block height in database
+			// and set higher block as start height
+			startHeight := utils.MaxInt64(config.Cfg.Parser.StartHeight, lastDbBlockHeight)
+
 			if start > 0 {
 				startHeight = start
 			}

cmd/start/cmd.go

@@ -8,6 +8,7 @@ import (
 	"time"
 
 	parsecmdtypes "github.com/forbole/juno/v3/cmd/parse/types"
+	"github.com/forbole/juno/v3/types/utils"
 
 	"github.com/forbole/juno/v3/logging"
 
@@ -126,6 +127,20 @@ func enqueueMissingBlocks(exportQueue types.HeightQueue, ctx *parser.Context) {
 	// Get the latest height
 	latestBlockHeight := mustGetLatestHeight(ctx)
 
+	lastDbBlockHeight, err := ctx.Database.GetLastBlockHeight()
+	if err != nil {
+		ctx.Logger.Error("failed to get last block height from database", "error", err)
+	}
+
+	// Get the start height, default to the config's height
+	startHeight := cfg.StartHeight
+
+	// Set startHeight to the latest height in database
+	// if is not set inside config.yaml file
+	if startHeight == 0 {
+		startHeight = utils.MaxInt64(1, lastDbBlockHeight)
+	}
+
 	if cfg.FastSync {
 		ctx.Logger.Info("fast sync is enabled, ignoring all previous blocks", "latest_block_height", latestBlockHeight)
 		for _, module := range ctx.Modules {
@@ -142,7 +157,7 @@ func enqueueMissingBlocks(exportQueue types.HeightQueue, ctx *parser.Context) {
 		}
 	} else {
 		ctx.Logger.Info("syncing missing blocks...", "latest_block_height", latestBlockHeight)
-		for i := cfg.StartHeight; i <= latestBlockHeight; i++ {
+		for i := startHeight; i <= latestBlockHeight; i++ {
 			ctx.Logger.Debug("enqueueing missing block", "height", i)
 			exportQueue <- i
 		}

database/database.go

@@ -16,6 +16,10 @@ type Database interface {
 	// An error is returned if the operation fails.
 	HasBlock(height int64) (bool, error)
 
+	// GetLastBlockHeight returns the last block height stored in database..
+	// An error is returned if the operation fails.
+	GetLastBlockHeight() (int64, error)
+
 	// SaveBlock will be called when a new block is parsed, passing the block itself
 	// and the transactions contained inside that block.
 	// An error is returned if the operation fails.

database/postgresql/postgresql.go

@@ -96,6 +96,22 @@ func (db *Database) HasBlock(height int64) (bool, error) {
 	return res, err
 }
 
+// GetLastBlockHeight returns the last block height stored inside the database
+func (db *Database) GetLastBlockHeight() (int64, error) {
+	stmt := `SELECT height FROM block ORDER BY height DESC LIMIT 1;`
+
+	var height int64
+	if err := db.Sql.QueryRow(stmt).Scan(&height); err != nil {
+		return 0, fmt.Errorf("error while getting last block height, error: %s", err)
+	}
+
+	if height == 0 {
+		return 0, fmt.Errorf("cannot get block height, no blocks saved")
+	}
+
+	return height, nil
+}
+
 // SaveBlock implements database.Database
 func (db *Database) SaveBlock(block *types.Block) error {
 	sqlStatement := `

types/utils/utils.go

@@ -51,3 +51,10 @@ func FindAttributeByKey(event abci.Event, attrKey string) (abci.EventAttribute,
 
 	return abci.EventAttribute{}, fmt.Errorf("no attribute with key %s found inside event with type %s", attrKey, event.Type)
 }
+
+func MaxInt64(a, b int64) int64 {
+	if a > b {
+		return a
+	}
+	return b
+}