//---
// fxos.vspace: A virtual space where code is being studied
//---

#ifndef LIBFXOS_VSPACE_H
#define LIBFXOS_VSPACE_H

#include <fxos/memory.h>
#include <fxos/util.h>
#include <fxos/os.h>
#include <fxos/symbols.h>

#include <optional>
#include <vector>
#include <cstdint>
#include <memory>

namespace FxOS {

/* A common interface for simulated memory */
class AbstractMemory
{
public:
	/* Checks if an address or interval is simulated */
	virtual bool covers(uint32_t addr, int size=1) const noexcept = 0;
	/* Check if a full region is simulated */
	virtual bool covers(MemoryRegion const &region) const noexcept;

	/* Returns the data located at the provided virtual address, nullptr if it
	   is not entirely covered. */
	virtual char const *translate(uint32_t addr, int size=1) const = 0;

	/* Returns the data located at the provided virtual address, and indicates
	   how much is available in *size. */
	virtual char const *translate_dynamic(uint32_t addr, int *size) const = 0;

	/* Read data from the memory. The following methods read data of
	   various types. (Not a template because of the restriction about
	   template specialization in non-namespaces scopes still in g++.)

	   When reading data, provide a virtual address. The address is saved
	   in the returned object for later printing or inspection. The
	   returned object Addressable<T> automatically converts to T when
	   used, and supports operator & which returns the original address.

	   The size parameter is only meaningful for variable-sized types such
	   as string, and ignored for fixed-size types such as integers. If the
	   desired object is not within the range of the simulated memory,
	   throws std::out_of_range. */

	/* Read integers with signed or unsigned extension. These functions do
	   not check alignment, because exceptionally the processor supports
	   unaligned operations (eg. movual.l). */
	Addressable<int8_t>   read_i8 (uint32_t addr) const;
	Addressable<uint8_t>  read_u8 (uint32_t addr) const;
	Addressable<int16_t>  read_i16(uint32_t addr) const;
	Addressable<uint16_t> read_u16(uint32_t addr) const;
	Addressable<int32_t>  read_i32(uint32_t addr) const;
	Addressable<uint32_t> read_u32(uint32_t addr) const;

	/* Read a non-NUL-terminated string */
	Addressable<std::string> read_str(uint32_t addr, size_t len) const;

	/* Search a binary pattern in the specified area. Returns the virtual
	   address of the first occurrence if any is found, [end] otherwise
	   (including if the range is empty or exceeds simulated memory). */
	virtual uint32_t search(uint32_t start, uint32_t end,
		void const *pattern, int size) const = 0;
};

/* A binding of a data buffer into a memory region of the target. */
struct Binding: public AbstractMemory
{
	/* Constructor from data buffer. An error is raised if the buffer is
	   not at least of the size of the region. In this case, a new buffer
	   can be constructed with the required size. */
	Binding(MemoryRegion region, Buffer buffer);

	/* Targeted region, might overlap with other bindings */
	MemoryRegion region;
	/* Underlying buffer (copy of the original one) */
	Buffer buffer;

	bool covers(uint32_t addr, int size=1) const noexcept override;
	bool covers(MemoryRegion const &region) const noexcept override;

	char const *translate(uint32_t addr, int size=1) const override;
	char const *translate_dynamic(uint32_t addr, int *size) const override;

	uint32_t search(uint32_t start, uint32_t end, void const *pattern,
		int size) const override;
};

/* A target description in the database; loadable, but not loaded yet */
struct Target
{
	/* Just a list of bindings to be formed */
	using Binding = std::pair<MemoryRegion,std::string>;
	std::vector<Binding> bindings;
	/* Also the MPU to be set */
	std::string mpu;
};

/* A composite space where regions can be bound dynamically */
class VirtualSpace: public AbstractMemory
{
public:
	/* Create an empty space with no regions */
	VirtualSpace();

	/* Create a new virtual space with a target loaded. */
	VirtualSpace(Target const &target,std::vector<std::string> const &folders);

	/* MPU used by this target, or an empty string if unspecified */
	std::string mpu;

	/* List of bindings */
	std::vector<Binding> const &bindings() const {
		return m_bindings;
	}

	/* OS analysis; performed on-demand. Returns the new or cached OS analysis,
	   and nullptr only if OS cannot be analyzed */
	OS *os_analysis(bool force=false);

	/* Cursor position, used by the interactive shell */
	uint32_t cursor;

	/* Symbol table */
	SymbolTable symbols;

	/* Bind a memory region from a buffer. The region can either be
	   standard (see <fxos/memory.h>) or custom.

	   If several loaded regions overlap on some addresses, *the last
	   loaded region will be used*. Thus, new regions can be loaded to
	   selectively override parts of the target.

	   An error is raised if the buffer is smaller than the region being
	   bound. */
	void bind_region(MemoryRegion const &region, Buffer const &buffer);

	bool covers(uint32_t addr, int size=1) const noexcept override;
	bool covers(MemoryRegion const &region) const noexcept override;

	char const *translate(uint32_t addr, int size=1) const override;
	char const *translate_dynamic(uint32_t addr, int *size) const override;

	uint32_t search(uint32_t start, uint32_t end, void const *pattern,
		int size) const override;

private:
	/* Bound regions (in order of binding) */
	std::vector<Binding> m_bindings;
	/* Buffers owned by the target (when loaded from description) */
	std::vector<Buffer> m_buffers;
	/* Current OS analyzer */
	std::unique_ptr<OS> m_os;
};

} /* namespace FxOS */

#endif /* LIBFXOS_VSPACE_H */