/* Memory manager.
 *
 * Author: Daniel Krebs <github@daniel-krebs.net>
 * SPDX-FileCopyrightText: 2014-2023 Institute for Automation of Complex Power Systems, RWTH Aachen University
 * SPDX-License-Identifier: Apache-2.0
 */

#pragma once

#include <cstdint>
#include <fmt/ostream.h>
#include <map>
#include <stdexcept>
#include <string>
#include <unistd.h>
#include <villas/config.hpp>
#include <villas/graph/directed.hpp>
#include <villas/log.hpp>

namespace villas {

// Translation between a local (master) to a foreign (slave) address space
//
// Memory translations can be chained together using the `+=` operator which is
// used internally by the MemoryManager to compute a translation through
// multiple hops (memory mappings).
class MemoryTranslation {
public:
  // MemoryTranslation
  // @param src	Base address of local address space
  // @param dst	Base address of foreign address space
  // @param size	Size of "memory window"
  MemoryTranslation(uintptr_t src, uintptr_t dst, size_t size)
      : src(src), dst(dst), size(size) {}

  uintptr_t getLocalAddr(uintptr_t addrInForeignAddrSpace) const;

  uintptr_t getForeignAddr(uintptr_t addrInLocalAddrSpace) const;

  size_t getSize() const { return size; }

  friend std::ostream &operator<<(std::ostream &stream,
                                  const MemoryTranslation &translation) {
    return stream << std::hex << "(src=0x" << translation.src << ", dst=0x"
                  << translation.dst << ", size=0x" << translation.size << ")";
  }

  // Merge two MemoryTranslations together
  MemoryTranslation &operator+=(const MemoryTranslation &other);

private:
  uintptr_t src; // Base address of local address space
  uintptr_t dst; // Base address of foreign address space
  size_t size;   // Size of "memory window"
};

// Global memory manager to resolve addresses across address spaces
//
// Every entity in the system has to register its (master) address space and
// create mappings to other (slave) address spaces that it can access. A
// directed graph is then constructed which allows to traverse addresses spaces
// through multiple mappings and resolve addresses through this "tunnel" of
// memory mappings.
class MemoryManager {
private:
  // This is a singleton, so private constructor ...
  MemoryManager()
      : memoryGraph("memory:graph"), logger(Log::get("memory:manager")) {
    pathCheckFunc = [&](const MemoryGraph::Path &path) {
      return this->pathCheck(path);
    };
  }

  // ... and no copying or assigning
  MemoryManager(const MemoryManager &) = delete;
  MemoryManager &operator=(const MemoryManager &) = delete;

  // Custom edge in memory graph representing a memory mapping
  //
  // A memory mapping maps from one address space into another and can only be
  // traversed in the forward direction which reflects the nature of real
  // memory mappings.
  //
  // Implementation Notes:
  // The member #src is the address in the "from" address space, where the
  // destination address space is mapped. The member #dest is the address in
  // the destination address space, where the mapping points to. Often, #dest
  // will be zero for mappings to hardware, but consider the example when
  // mapping FPGA to application memory:
  // The application allocates a block 1kB at address 0x843001000 in its
  // address space. The mapping would then have a #dest address of 0x843001000
  // and a #size of 1024.
  class Mapping : public graph::Edge {
  public:
    std::string name; // Human-readable name
    uintptr_t src;    // Base address in "from" address space
    uintptr_t dest;   // Base address in "to" address space
    size_t size;      // Size of the mapping

    friend std::ostream &operator<<(std::ostream &stream,
                                    const Mapping &mapping) {
      return stream << static_cast<const Edge &>(mapping) << " = "
                    << mapping.name << std::hex << " (src=0x" << mapping.src
                    << ", dest=0x" << mapping.dest << ", size=0x"
                    << mapping.size << ")";
    }

    std::string toString() {
      std::stringstream s;
      s << *this;
      return s.str();
    }
  };

  // Custom vertex in memory graph representing an address space
  //
  // Since most information in the memory graph is stored in the edges (memory
  // mappings), this is just a small extension to the default vertex. It only
  // associates an additional string #name for human-readability.
  class AddressSpace : public graph::Vertex {
  public:
    std::string name; // Human-readable name

    friend std::ostream &operator<<(std::ostream &stream,
                                    const AddressSpace &addrSpace) {
      return stream << static_cast<const Vertex &>(addrSpace) << " = "
                    << addrSpace.name;
    }
  };

  // Memory graph with custom edges and vertices for address resolution
  using MemoryGraph = graph::DirectedGraph<AddressSpace, Mapping>;

public:
  using AddressSpaceId = MemoryGraph::VertexIdentifier;
  using MappingId = MemoryGraph::EdgeIdentifier;

  struct InvalidTranslation : public std::exception {};

  // Get singleton instance
  static MemoryManager &get();

  MemoryGraph &getGraph() { return memoryGraph; }
  void printGraph();

  AddressSpaceId getProcessAddressSpace() {
    return getOrCreateAddressSpace("process");
  }

  AddressSpaceId getPciAddressSpace() {
    return getOrCreateAddressSpace("pcie");
  }

  AddressSpaceId
  getProcessAddressSpaceMemoryBlock(const std::string &memoryBlock) {
    return getOrCreateAddressSpace(
        getSlaveAddrSpaceName("process", memoryBlock));
  }

  AddressSpaceId getOrCreateAddressSpace(std::string name);

  void removeAddressSpace(const AddressSpaceId &addrSpaceId) {
    memoryGraph.removeVertex(addrSpaceId);
  }

  // Create a default mapping
  MappingId createMapping(uintptr_t src, uintptr_t dest, size_t size,
                          const std::string &name, AddressSpaceId fromAddrSpace,
                          AddressSpaceId toAddrSpace);

  // Add a mapping
  //
  // Can be used to derive from Mapping in order to implement custom
  // constructor/destructor.
  MappingId addMapping(std::shared_ptr<Mapping> mapping,
                       AddressSpaceId fromAddrSpace,
                       AddressSpaceId toAddrSpace);

  AddressSpaceId findAddressSpace(const std::string &name);

  std::list<AddressSpaceId> findPath(const AddressSpaceId &fromAddrSpaceId,
                                     const AddressSpaceId &toAddrSpaceId);

  MemoryTranslation getTranslation(const AddressSpaceId &fromAddrSpaceId,
                                   const AddressSpaceId &toAddrSpaceId);

  // cppcheck-suppress passedByValue
  MemoryTranslation
  getTranslationFromProcess(const AddressSpaceId &foreignAddrSpaceId) {
    return getTranslation(getProcessAddressSpace(), foreignAddrSpaceId);
  }

  static std::string getSlaveAddrSpaceName(const std::string &ipInstance,
                                           const std::string &memoryBlock) {
    return ipInstance + "/" + memoryBlock;
  }

  static std::string getMasterAddrSpaceName(const std::string &ipInstance,
                                            const std::string &busInterface) {
    return ipInstance + ":" + busInterface;
  }

private:
  // Convert a Mapping to MemoryTranslation for calculations
  static MemoryTranslation getTranslationFromMapping(const Mapping &mapping) {
    return MemoryTranslation(mapping.src, mapping.dest, mapping.size);
  }

  bool pathCheck(const MemoryGraph::Path &path);

  // Directed graph that stores address spaces and memory mappings
  MemoryGraph memoryGraph;

  // Cache mapping of names to address space ids for fast lookup
  std::map<std::string, AddressSpaceId> addrSpaceLookup;

  // Logger for universal access in this class
  Logger logger;

  MemoryGraph::check_path_fn pathCheckFunc;

  // Static pointer to global instance, because this is a singleton
  static MemoryManager *instance;
};

} // namespace villas

#ifndef FMT_LEGACY_OSTREAM_FORMATTER
template <>
class fmt::formatter<villas::MemoryTranslation>
    : public fmt::ostream_formatter {};
template <>
class fmt::formatter<villas::MemoryManager::Mapping>
    : public fmt::ostream_formatter {};
template <>
class fmt::formatter<villas::MemoryManager::AddressSpaceId>
    : public fmt::ostream_formatter {};
#endif