starknet_contract.cairo

%lang starknet

from starkware.cairo.common.alloc import alloc
from starkware.cairo.common.cairo_builtins import HashBuiltin
from starkware.cairo.common.cairo_builtins import BitwiseBuiltin

from btc_header import BTCHeader, process_header, prepare_header

@storage_var
func block_header_lo(number : felt) -> (hash_lo : felt):
end

@storage_var
func block_header_hi(number : felt) -> (hash_hi : felt):
end

@external
func process_block{
    syscall_ptr : felt*, pedersen_ptr : HashBuiltin*, bitwise_ptr : BitwiseBuiltin*, range_check_ptr
}(height : felt, data_len : felt, data : felt*):
    alloc_locals

    # Retrieve previous block header hash (or zero hash if genesis)
    let (local prev_hash : felt*) = alloc()
    if height == 0:
        assert prev_hash[0] = 0
        assert prev_hash[1] = 0
        tempvar syscall_ptr = syscall_ptr
        tempvar range_check_ptr = range_check_ptr
        tempvar pedersen_ptr = pedersen_ptr
    else:
        let (lo) = block_header_lo.read(height - 1)
        let (hi) = block_header_hi.read(height - 1)
        assert prev_hash[0] = lo
        assert prev_hash[1] = hi
        tempvar syscall_ptr = syscall_ptr
        tempvar range_check_ptr = range_check_ptr
        tempvar pedersen_ptr = pedersen_ptr
    end
    tempvar syscall_ptr = syscall_ptr
    tempvar range_check_ptr = range_check_ptr
    tempvar pedersen_ptr = pedersen_ptr
    # Verify provided block header
    let (local header) = prepare_header(data)
    let (local block_hash) = process_header(header, prev_hash)

    local syscall_ptr : felt* = syscall_ptr
    # Write current header to storage
    block_header_lo.write(height, block_hash[0])
    block_header_hi.write(height, block_hash[1])

    return ()
end