global: snapshot

crates/brk_reader/src/decode.rs

@@ -0,0 +1,73 @@
+use bitcoin::{Transaction, VarInt, block::Header, consensus::Decodable, io::Cursor};
+use brk_error::Result;
+use brk_rpc::Client;
+use brk_types::{BlkMetadata, Block, Height, ReadBlock};
+
+use crate::{XORBytes, XORIndex};
+
+/// Margin for timestamp non-monotonicity
+const TIMESTAMP_MARGIN: u32 = 3 * 3600;
+
+#[allow(clippy::too_many_arguments)]
+pub fn decode_block(
+    mut bytes: Vec<u8>,
+    metadata: BlkMetadata,
+    client: &Client,
+    mut xor_i: XORIndex,
+    xor_bytes: XORBytes,
+    start: Option<Height>,
+    end: Option<Height>,
+    start_time: u32,
+    end_time: u32,
+) -> Result<Option<ReadBlock>> {
+    xor_i.bytes(bytes.as_mut_slice(), xor_bytes);
+
+    let mut cursor = Cursor::new(bytes);
+
+    let header = Header::consensus_decode(&mut cursor)?;
+
+    // Skip blocks clearly outside the target range using header timestamp
+    if header.time < start_time.saturating_sub(TIMESTAMP_MARGIN)
+        || (end_time > 0 && header.time > end_time.saturating_add(TIMESTAMP_MARGIN))
+    {
+        return Ok(None);
+    }
+
+    let hash = header.block_hash();
+
+    let Ok(block_header_result) = client.get_block_header_info(&hash) else {
+        return Ok(None);
+    };
+
+    let height = Height::from(block_header_result.height);
+
+    if start.is_some_and(|s| s > height) || end.is_some_and(|e| e < height) {
+        return Ok(None);
+    }
+    if block_header_result.confirmations <= 0 {
+        return Ok(None);
+    }
+
+    let tx_count = VarInt::consensus_decode(&mut cursor)?.0 as usize;
+
+    let mut txdata = Vec::with_capacity(tx_count);
+    let mut tx_metadata = Vec::with_capacity(tx_count);
+    let mut tx_offsets = Vec::with_capacity(tx_count);
+    for _ in 0..tx_count {
+        let offset = cursor.position() as u32;
+        tx_offsets.push(offset);
+        let position = metadata.position() + offset;
+        let tx = Transaction::consensus_decode(&mut cursor)?;
+        txdata.push(tx);
+        let len = cursor.position() as u32 - offset;
+        tx_metadata.push(BlkMetadata::new(position, len));
+    }
+
+    let block_bytes = cursor.into_inner();
+
+    let block = bitcoin::Block { header, txdata };
+    let mut block = Block::from((height, hash, block));
+    block.set_raw_data(block_bytes, tx_offsets);
+
+    Ok(Some(ReadBlock::from((block, metadata, tx_metadata))))
+}