Add block request (#268)

* Add block request

internal/chain/service.go

@@ -0,0 +1,238 @@
+package chain
+
+import (
+	"errors"
+	"fmt"
+	"sync"
+	"time"
+
+	"github.com/eigerco/strawberry/internal/block"
+	"github.com/eigerco/strawberry/internal/crypto"
+	"github.com/eigerco/strawberry/internal/jamtime"
+	"github.com/eigerco/strawberry/internal/store"
+	"github.com/eigerco/strawberry/pkg/db/pebble"
+	"github.com/eigerco/strawberry/pkg/network"
+)
+
+// BlockService manages the node's view of the blockchain state, including:
+// - Known leaf blocks (blocks with no known children)
+// - Latest finalized block
+// - Block storage and retrieval
+//
+// It handles block announcements according to UP 0 protocol specification,
+// maintaining the set of leaf blocks and tracking finalization status.
+type BlockService struct {
+	Mu              sync.RWMutex
+	KnownLeaves     map[crypto.Hash]jamtime.Timeslot // Maps leaf block hashes to their timeslots
+	LatestFinalized LatestFinalized                  // Tracks the most recently finalized block
+	Store           *store.Chain                     // Persistent block storage
+}
+
+// LatestFinalized represents the latest finalized block in the chain.
+// A block is considered finalized when it has a chain of 5 descendant blocks
+// built on top of it according to the finalization rules.
+type LatestFinalized struct {
+	Hash          crypto.Hash      // Hash of the finalized block
+	TimeSlotIndex jamtime.Timeslot // Timeslot of the finalized block
+}
+
+// Leaf represents a block with no known children (a tip of the chain).
+// The BlockService tracks all known leaves to implement the UP 0 protocol's
+// requirement of announcing all leaves in handshake messages.
+type Leaf struct {
+	Hash          crypto.Hash      // Hash of the leaf block
+	TimeSlotIndex jamtime.Timeslot // Timeslot of the leaf block
+}
+
+// NewBlockService initializes a new BlockService with:
+// - Empty leaf block set
+// - Persistent block storage using PebbleDB
+// - Genesis block as the latest finalized block
+func NewBlockService() (*BlockService, error) {
+	kvStore, err := pebble.NewKVStore()
+	if err != nil {
+		return nil, err
+	}
+	chain := store.NewChain(kvStore)
+	bs := &BlockService{
+		Store:       chain,
+		KnownLeaves: make(map[crypto.Hash]jamtime.Timeslot),
+	}
+	// Initialize by finding leaves and finalized block
+	if err := bs.initializeState(); err != nil {
+		// Log error but continue - we can recover state as we process blocks
+		fmt.Printf("Failed to initialize block manager state: %v\n", err)
+	}
+	return bs, nil
+}
+
+// initializeState sets up the initial blockchain state:
+// 1. Creates and stores the genesis block
+// 2. Sets genesis as the latest finalized block
+//
+// TODO: This is still a `mock` implementation.
+func (bs *BlockService) initializeState() error {
+	// For now use genesis block
+	genesisHeader := block.Header{
+		ParentHash:       crypto.Hash{1},
+		TimeSlotIndex:    jamtime.Timeslot(1),
+		BlockAuthorIndex: 0,
+	}
+	hash, err := genesisHeader.Hash()
+	fmt.Printf("hash: %v\n", hash)
+	if err != nil {
+		return fmt.Errorf("failed to hash genesis block: %w", err)
+	}
+	if err := bs.Store.PutHeader(genesisHeader); err != nil {
+		return fmt.Errorf("failed to store genesis block: %w", err)
+	}
+	b := block.Block{
+		Header: genesisHeader,
+	}
+	if err := bs.Store.PutBlock(b); err != nil {
+		return fmt.Errorf("failed to store genesis block: %w", err)
+	}
+	bs.Mu.Lock()
+	defer bs.Mu.Unlock()
+	bs.LatestFinalized = LatestFinalized{
+		Hash:          hash,
+		TimeSlotIndex: genesisHeader.TimeSlotIndex,
+	}
+	return nil
+}
+
+// checkFinalization determines if a block can be finalized by:
+// 1. Walking back 5 generations from the given block hash
+// 2. If a complete chain of 5 blocks exists, finalizing the oldest block
+// 3. Updating the latest finalized pointer
+// 4. Removing the finalized block from the leaf set if present
+//
+// Returns nil if finalization check succeeds, error if any operations fail.
+// Note: May return nil even if finalization isn't possible (e.g., missing ancestors).
+// This is due to genesis block handling and is not considered an error.
+func (bs *BlockService) checkFinalization(hash crypto.Hash) error {
+	// Start from current header and walk back 6 generations
+	currentHash := hash
+	var ancestorChain []block.Header
+
+	// Walk back 6`` generations
+	for i := 0; i < 6; i++ {
+		header, err := bs.Store.GetHeader(currentHash)
+		if err != nil {
+			if errors.Is(err, store.ErrHeaderNotFound) {
+				// If we can't find a parent, we can't finalize
+				return nil
+			}
+			return fmt.Errorf("failed to get header in chain: %w", err)
+		}
+
+		ancestorChain = append(ancestorChain, header)
+		currentHash = header.ParentHash
+	}
+
+	// Get the oldest header (the one we'll finalize)
+	finalizeHeader := ancestorChain[len(ancestorChain)-1]
+	finalizeHash, err := finalizeHeader.Hash()
+	if err != nil {
+		return fmt.Errorf("failed to hash header during finalization: %w", err)
+	}
+
+	bs.RemoveLeaf(finalizeHash)
+	bs.UpdateLatestFinalized(finalizeHash, finalizeHeader.TimeSlotIndex)
+
+	return nil
+}
+
+// HandleNewHeader processes a new block header announcement by:
+// 1. Storing the header in persistent storage
+// 2. Updating the leaf block set (removing parent, adding new block)
+// 3. Checking if the parent block can now be finalized
+//
+// This implements the core block processing logic required by UP 0 protocol,
+// maintaining the node's view of chain tips and finalization status.
+func (bs *BlockService) HandleNewHeader(header *block.Header) error {
+	// Get the header hash
+	hash, err := header.Hash()
+	if err != nil {
+		return fmt.Errorf("failed to hash header: %w", err)
+	}
+	// Need to verify this block is a descendant of latest finalized block
+	// before considering it as a potential leaf
+	isDescendant, err := bs.isDescendantOfFinalized(header)
+	if err != nil {
+		return fmt.Errorf("failed to check if block is descendant of finalized: %w", err)
+	}
+	if !isDescendant {
+		return fmt.Errorf("block %s is not a descendant of latest finalized block", hash)
+	}
+
+	// First store the header
+	if err := bs.Store.PutHeader(*header); err != nil {
+		return fmt.Errorf("failed to store header: %w", err)
+	}
+
+	// Only update leaves if this is a descendant of finalized block
+	bs.RemoveLeaf(header.ParentHash)
+	bs.AddLeaf(hash, header.TimeSlotIndex)
+
+	// Check if this creates a finalization condition starting from parent
+	if err := bs.checkFinalization(header.ParentHash); err != nil {
+		// Log but don't fail on finalization check errors
+		fmt.Printf("Failed to check finalization: %v\n", err)
+	}
+
+	return nil
+}
+
+// UpdateLatestFinalized updates the latest finalized block pointer.
+func (bs *BlockService) UpdateLatestFinalized(hash crypto.Hash, slot jamtime.Timeslot) {
+	bs.Mu.Lock()
+	defer bs.Mu.Unlock()
+	bs.LatestFinalized = LatestFinalized{Hash: hash, TimeSlotIndex: slot}
+	network.LogBlockEvent(time.Now(), "finalizing", hash, slot.ToEpoch(), slot)
+}
+
+// AddLeaf adds a block to the set of known leaves.
+func (bs *BlockService) AddLeaf(hash crypto.Hash, slot jamtime.Timeslot) {
+	bs.Mu.Lock()
+	defer bs.Mu.Unlock()
+	bs.KnownLeaves[hash] = slot
+}
+
+// RemoveLeaf removes a block from the set of known leaves.
+func (bs *BlockService) RemoveLeaf(hash crypto.Hash) {
+	bs.Mu.Lock()
+	defer bs.Mu.Unlock()
+	delete(bs.KnownLeaves, hash)
+}
+
+// isDescendantOfFinalized checks if a block is a descendant of the latest finalized block
+// by walking back through its ancestors until we either:
+// - Find the latest finalized block (true)
+// - Find a different block at the same height as latest finalized (false)
+// - Can't find a parent (error)
+func (bs *BlockService) isDescendantOfFinalized(header *block.Header) (bool, error) {
+	bs.Mu.RLock()
+	finalizedSlot := bs.LatestFinalized.TimeSlotIndex
+	finalizedHash := bs.LatestFinalized.Hash
+	bs.Mu.RUnlock()
+
+	current := header
+	for current.TimeSlotIndex > finalizedSlot {
+		parent, err := bs.Store.GetHeader(current.ParentHash)
+		if err != nil {
+			return false, fmt.Errorf("failed to get parent block: %w", err)
+		}
+		current = &parent
+	}
+
+	// If we found the finalized block, this is a descendant
+	if current.TimeSlotIndex == finalizedSlot {
+		currentHash, err := current.Hash()
+		if err != nil {
+			return false, err
+		}
+		return currentHash == finalizedHash, nil
+	}
+	return false, nil
+}

internal/chain/service_test.go

@@ -0,0 +1,77 @@
+package chain
+
+import (
+	"testing"
+
+	"github.com/eigerco/strawberry/internal/block"
+	"github.com/eigerco/strawberry/internal/crypto"
+	"github.com/eigerco/strawberry/internal/jamtime"
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestCheckFinalization(t *testing.T) {
+	// Create a new BlockService
+	bs, err := NewBlockService()
+	require.NoError(t, err)
+
+	// Create a chain of 7 headers (0->1->2->3->4->5->6)
+	// Block 1 will have 5 descendants (2,3,4,5,6) and should be finalized
+	var headers []block.Header
+	var hashes []crypto.Hash
+	parentHash := crypto.Hash{} // Zero hash for first block
+
+	// Create and store headers
+	for i := uint32(0); i < 7; i++ {
+		header := block.Header{
+			TimeSlotIndex: jamtime.Timeslot(i),
+			ParentHash:    parentHash,
+		}
+
+		// Store the header
+		err := bs.Store.PutHeader(header)
+		require.NoError(t, err)
+
+		// Get and store the hash for next iteration
+		hash, err := header.Hash()
+		require.NoError(t, err)
+		parentHash = hash
+
+		headers = append(headers, header)
+		hashes = append(hashes, hash)
+	}
+
+	// Add some headers as leaves
+	bs.AddLeaf(hashes[6], 6) // Last one is a leaf
+
+	// Try to finalize using the last header
+	err = bs.checkFinalization(hashes[6])
+	require.NoError(t, err)
+
+	// Verify:
+	// 1. Header[1] should be finalized (having 5 descendants: 2,3,4,5,6)
+	// 2. Leaves should be updated
+	// 3. LatestFinalized should be set to header[1]
+
+	// Check LatestFinalized
+	assert.Equal(t, hashes[1], bs.LatestFinalized.Hash)
+	assert.Equal(t, headers[1].TimeSlotIndex, bs.LatestFinalized.TimeSlotIndex)
+
+	// Check leaves - only block 6 should remain as leaf
+	_, exists5 := bs.KnownLeaves[hashes[5]]
+	_, exists6 := bs.KnownLeaves[hashes[6]]
+	assert.False(t, exists5, "hash[5] should not be a leaf")
+	assert.True(t, exists6, "hash[6] should still be a leaf")
+	assert.Equal(t, 1, len(bs.KnownLeaves), "should only have one leaf")
+
+	// Try finalizing again with same hash - should not change anything
+	prevFinalized := bs.LatestFinalized
+	err = bs.checkFinalization(hashes[6])
+	require.NoError(t, err)
+	assert.Equal(t, prevFinalized, bs.LatestFinalized, "finalization should not change on second attempt")
+
+	// Try finalizing with non-existent hash
+	err = bs.checkFinalization(crypto.Hash{1, 2, 3})
+	require.NoError(t, err) // Should return nil error as per our implementation
+	assert.Equal(t, prevFinalized, bs.LatestFinalized, "finalization should not change with invalid hash")
+}