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modules/network/include/bytebuffer/ByteBufferReader.hpp

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+#pragma once
+
+#include <cstring>
+#include <span>
+#include <spdlog/spdlog.h>
+
+namespace tw::net {
+
+/**
+ * Circular byte buffer.
+ */
+class ByteBufferReader {
+public:
+    ByteBufferReader(std::span<std::byte> target) : buffer(target), readOffset(0) {}
+
+    ByteBufferReader(std::span<const std::byte> target) : buffer(target), readOffset(0) {}
+
+    size_t peek_bytes(void* dst, size_t size, size_t offset = 0) {
+        if(remaining() - offset < size) {
+            spdlog::warn("Could not peek entire frame, remaining: {}/{}", remaining() - offset, size);
+            return 0;
+        }
+
+        size_t cursor = readOffset + offset;
+
+        // if(cursor + size <= buffer.size()) {
+        std::memcpy(dst, buffer.data() + cursor, size);
+        // } else {
+        //     size_t firstPart = buffer.size() - cursor;
+        //     std::memcpy(dst, buffer.data() + cursor, firstPart);
+        //     std::memcpy((std::byte*)dst + firstPart, buffer.data(), size - firstPart);
+        // }
+
+        return size;
+    }
+
+    template<typename T>
+    size_t pop_bytes(T* dst) {
+        return pop_bytes(dst, sizeof(T));
+    }
+
+    size_t pop_bytes(void* dst, size_t size) {
+        size_t peeked = peek_bytes(dst, size);
+        if(peeked < size) {
+            spdlog::warn("Could not read entire frame, peeked only: {}/{}", peeked, size);
+            return 0;
+        }
+
+        skip(size);
+        return size;
+    }
+
+    size_t pop_bytes(std::span<std::byte> dst) {
+        return pop_bytes(dst.data(), dst.size());
+    }
+
+    size_t position() const {
+        return readOffset;
+    }
+
+    size_t remaining() const {
+        return buffer.size() - readOffset;
+    }
+
+    void reset() {
+        readOffset = 0;
+    }
+
+    void skip(size_t bytes) {
+        readOffset = (readOffset + std::min(bytes, remaining()));
+    }
+
+private:
+    std::span<const std::byte> buffer;
+    size_t readOffset = 0;
+};
+
+} // namespace tw::net