/*
 * Portions of this file are copyright Rebirth contributors and licensed as
 * described in COPYING.txt.
 * Portions of this file are copyright Parallax Software and licensed
 * according to the Parallax license below.
 * See COPYING.txt for license details.

THE COMPUTER CODE CONTAINED HEREIN IS THE SOLE PROPERTY OF PARALLAX
SOFTWARE CORPORATION ("PARALLAX").  PARALLAX, IN DISTRIBUTING THE CODE TO
END-USERS, AND SUBJECT TO ALL OF THE TERMS AND CONDITIONS HEREIN, GRANTS A
ROYALTY-FREE, PERPETUAL LICENSE TO SUCH END-USERS FOR USE BY SUCH END-USERS
IN USING, DISPLAYING,  AND CREATING DERIVATIVE WORKS THEREOF, SO LONG AS
SUCH USE, DISPLAY OR CREATION IS FOR NON-COMMERCIAL, ROYALTY OR REVENUE
FREE PURPOSES.  IN NO EVENT SHALL THE END-USER USE THE COMPUTER CODE
CONTAINED HEREIN FOR REVENUE-BEARING PURPOSES.  THE END-USER UNDERSTANDS
AND AGREES TO THE TERMS HEREIN AND ACCEPTS THE SAME BY USE OF THIS FILE.
COPYRIGHT 1993-1999 PARALLAX SOFTWARE CORPORATION.  ALL RIGHTS RESERVED.
*/

/*
 *
 * Include file for functions which need to access segment data structure.
 *
 */

#pragma once

#include <physfs.h>
#include "pstypes.h"
#include "maths.h"
#include "vecmat.h"
#include "dxxsconf.h"

#ifdef __cplusplus
#include <cassert>
#include <cstdint>
#include <stdexcept>
#include "countarray.h"
#include "valptridx.h"
#include "objnum.h"
#include "segnum.h"
#include "pack.h"

#include "compiler-type_traits.h"
#include "fwd-segment.h"

inline namespace dcx {

#if defined(DXX_BUILD_DESCENT_I) || defined(DXX_BUILD_DESCENT_II)
// Returns true if segnum references a child, else returns false.
// Note that -1 means no connection, -2 means a connection to the outside world.
static inline bool IS_CHILD(segnum_t s)
{
	return s != segment_none && s != segment_exit;
}
#endif

//Structure for storing u,v,light values.
//NOTE: this structure should be the same as the one in 3d.h
struct uvl
{
	fix u, v, l;
};

enum side_type : uint8_t
{
	SIDE_IS_QUAD = 1,		// render side as quadrilateral
	SIDE_IS_TRI_02 = 2,	// render side as two triangles, triangulated along edge from 0 to 2
	SIDE_IS_TRI_13 = 3,	 // render side as two triangles, triangulated along edge from 1 to 3
};

struct wallnum_t : prohibit_void_ptr<wallnum_t>
{
	typedef int16_t integral_type;
	integral_type value;
	wallnum_t() = default;
	wallnum_t(const integral_type &v) : value(v)
	{
#ifdef DXX_HAVE_BUILTIN_CONSTANT_P
		if (__builtin_constant_p(v))
			DXX_ALWAYS_ERROR_FUNCTION(dxx_trap_constant_wall, "constant wall number constructed");
#endif
	}
	wallnum_t &operator=(integral_type v)
	{
#ifdef DXX_HAVE_BUILTIN_CONSTANT_P
		if (__builtin_constant_p(v))
			DXX_ALWAYS_ERROR_FUNCTION(dxx_trap_constant_wall, "constant wall number assigned");
#endif
		value = v;
		return *this;
	}
	template <integral_type I>
		wallnum_t &operator=(const wall_magic_constant_t<I> &)
		{
			value = I;
			return *this;
		}
	bool operator==(const wallnum_t &v) const { return value == v.value; }
	bool operator==(const int &v) const
	{
#ifdef DXX_HAVE_BUILTIN_CONSTANT_P
		if (__builtin_constant_p(v))
			DXX_ALWAYS_ERROR_FUNCTION(dxx_trap_constant_wall, "constant wall number compared");
#endif
		return value == v;
	}
	template <integral_type I>
		bool operator==(const wall_magic_constant_t<I> &) const { return value == I; }
	template <typename T>
		bool operator!=(const T &v) const { return !(*this == v); }
	template <typename T>
		bool operator==(const T &v) const = delete;
	template <typename T>
		bool operator<(const T &v) const
		{
			static_assert(tt::is_integral<T>::value, "non-integral wall number compared");
#ifdef DXX_HAVE_BUILTIN_CONSTANT_P
			if (__builtin_constant_p(v))
				DXX_ALWAYS_ERROR_FUNCTION(dxx_trap_constant_wall, "constant wall number compared");
#endif
			return value < v;
		}
	template <typename T>
		bool operator>(const T &v) const
		{
			return v < *this;
		}
	template <typename T>
		bool operator<=(const T &) const = delete;
	template <typename T>
		bool operator>=(const T &) const = delete;
	constexpr operator integral_type() const { return value; }
	operator integral_type &() { return value; }
};

struct side
{
	struct illegal_type;
	side_type m_type;           // replaces num_faces and tri_edge, 1 = quad, 2 = 0:2 triangulation, 3 = 1:3 triangulation
	const side_type &get_type() const { return m_type; }
	void set_type(side_type t) { m_type = t; }
	inline void set_type(unsigned t);
	wallnum_t wall_num;
	short   tmap_num;
	short   tmap_num2;
	array<uvl, 4>     uvls;
	array<vms_vector, 2> normals;  // 2 normals, if quadrilateral, both the same.
};

}

#if defined(DXX_BUILD_DESCENT_I) || defined(DXX_BUILD_DESCENT_II)
inline namespace dsx {

struct segment {
#ifdef EDITOR
	segnum_t   segnum;     // segment number, not sure what it means
	short   group;      // group number to which the segment belongs.
#endif
	objnum_t objects;    // pointer to objects in this segment
	array<segnum_t, MAX_SIDES_PER_SEGMENT>   children;    // indices of 6 children segments, front, left, top, right, bottom, back
	//      If bit n (1 << n) is set, then side #n in segment has had light subtracted from original (editor-computed) value.
	ubyte light_subtracted;
#if defined(DXX_BUILD_DESCENT_II)
	uint8_t slide_textures;
#endif
	array<int, MAX_VERTICES_PER_SEGMENT>     verts;    // vertex ids of 4 front and 4 back vertices
	ubyte   special;    // what type of center this is
	sbyte   matcen_num; // which center segment is associated with.
#if defined(DXX_BUILD_DESCENT_I)
	short   value;
#elif defined(DXX_BUILD_DESCENT_II)
	sbyte   value;
	ubyte   s2_flags;
#endif
	fix     static_light;
	array<side, MAX_SIDES_PER_SEGMENT>    sides;       // 6 sides
};

}
#endif

inline namespace dcx {

struct count_segment_array_t : public count_array_t<segnum_t, MAX_SEGMENTS> {};

struct group
{
	struct segment_array_type_t : public count_segment_array_t {};
	struct vertex_array_type_t : public count_array_t<int, MAX_VERTICES> {};
	segment_array_type_t segments;
	vertex_array_type_t vertices;
	void clear()
	{
		segments.clear();
		vertices.clear();
	}
};

}

#if defined(DXX_BUILD_DESCENT_I) || defined(DXX_BUILD_DESCENT_II)
#define Highest_segment_index Segments.highest

DEFINE_VALPTRIDX_SUBTYPE(seg, segment, segnum_t, Segments);
#endif

inline namespace dcx {

// Globals from mglobal.c
struct vertex : vms_vector
{
	vertex() = default;
	vertex(const fix &a, const fix &b, const fix &c) :
		vms_vector{a, b, c}
	{
	}
	explicit vertex(const vms_vector &v) :
		vms_vector(v)
	{
	}
};

}

#if defined(DXX_BUILD_DESCENT_I) || defined(DXX_BUILD_DESCENT_II)
struct side::illegal_type : std::runtime_error
{
	csegptr_t m_segment;
	const side *m_side;
	illegal_type(csegptr_t seg, const side *s) :
		runtime_error("illegal side type"),
		m_segment(seg), m_side(s)
	{
	}
	illegal_type(const side *s) :
		runtime_error("illegal side type"),
		m_segment(nullptr), m_side(s)
	{
	}
};

void side::set_type(unsigned t)
{
	switch (t)
	{
		case SIDE_IS_QUAD:
		case SIDE_IS_TRI_02:
		case SIDE_IS_TRI_13:
			set_type(static_cast<side_type>(t));
			break;
		default:
			throw illegal_type(this);
	}
}

inline namespace dsx {

#if defined(DXX_BUILD_DESCENT_II)
// New stuff, 10/14/95: For shooting out lights and monitors.
// Light cast upon vert_light vertices in segnum:sidenum by some light
struct delta_light : prohibit_void_ptr<delta_light>
{
	segnum_t   segnum;
	sbyte   sidenum;
	array<ubyte, 4>   vert_light;
};

// Light at segnum:sidenum casts light on count sides beginning at index (in array Delta_lights)
struct dl_index {
	segnum_t   segnum;
	sbyte   sidenum;
	uint8_t count;
	uint16_t index;
};
#endif

}
#endif

inline namespace dcx {

template <typename T, unsigned bits>
class visited_segment_mask_t
{
	static_assert(bits == 1 || bits == 2 || bits == 4, "bits must align in bytes");
protected:
	enum
	{
		divisor = 8 / bits,
	};
	typedef array<ubyte, (MAX_SEGMENTS + (divisor - 1)) / divisor> array_t;
	typedef typename array_t::size_type size_type;
	array_t a;
	struct base_maskproxy_t
	{
		unsigned m_shift;
		unsigned shift() const
		{
			return m_shift * bits;
		}
		static unsigned bitmask_low_aligned()
		{
			return (1 << bits) - 1;
		}
		typename array_t::value_type mask() const
		{
			return bitmask_low_aligned() << shift();
		}
		base_maskproxy_t(unsigned shift) :
			m_shift(shift)
		{
		}
	};
	template <typename R>
	struct tmpl_maskproxy_t : public base_maskproxy_t
	{
		R m_byte;
		tmpl_maskproxy_t(R byte, unsigned shift) :
			base_maskproxy_t(shift), m_byte(byte)
		{
		}
	};
	template <typename R, typename A>
	static R make_maskproxy(A &a, size_type segnum)
	{
		size_type idx = segnum / divisor;
		if (idx >= a.size())
			throw std::out_of_range("index exceeds segment range");
		size_type bit = segnum % divisor;
		return R(a[idx], bit);
	}
public:
	visited_segment_mask_t()
	{
		clear();
	}
	void clear()
	{
		a = {};
	}
};

class visited_segment_bitarray_t : public visited_segment_mask_t<bool, 1>
{
	template <typename R>
	struct tmpl_bitproxy_t : public tmpl_maskproxy_t<R>
	{
		tmpl_bitproxy_t(R byte, unsigned shift) :
			tmpl_maskproxy_t<R>(byte, shift)
		{
		}
		explicit operator bool() const
		{
			return !!(this->m_byte & this->mask());
		}
		operator int() const = delete;
	};
	struct bitproxy_t : public tmpl_bitproxy_t<array_t::reference>
	{
		bitproxy_t(array_t::reference byte, unsigned shift) :
			tmpl_bitproxy_t<array_t::reference>(byte, shift)
		{
		}
		bitproxy_t& operator=(bool b)
		{
			if (b)
				this->m_byte |= this->mask();
			else
				this->m_byte &= ~this->mask();
			return *this;
		}
		bitproxy_t& operator=(int) = delete;
	};
	typedef tmpl_bitproxy_t<array_t::const_reference> const_bitproxy_t;
public:
	bitproxy_t operator[](size_type segnum)
	{
		return make_maskproxy<bitproxy_t>(a, segnum);
	}
	const_bitproxy_t operator[](size_type segnum) const
	{
		return make_maskproxy<const_bitproxy_t>(a, segnum);
	}
};

template <unsigned bits>
class visited_segment_multibit_array_t : public visited_segment_mask_t<unsigned, bits>
{
	typedef typename visited_segment_mask_t<unsigned, bits>::array_t array_t;
	typedef typename visited_segment_mask_t<unsigned, bits>::size_type size_type;
	template <typename R>
	struct tmpl_multibit_proxy_t : public visited_segment_mask_t<unsigned, bits>::template tmpl_maskproxy_t<R>
	{
		tmpl_multibit_proxy_t(R byte, unsigned shift) :
			visited_segment_mask_t<unsigned, bits>::template tmpl_maskproxy_t<R>(byte, shift)
		{
		}
		explicit operator bool() const
		{
			return !!(this->m_byte & this->mask());
		}
		operator unsigned() const
		{
			return (this->m_byte >> this->shift()) & this->bitmask_low_aligned();
		}
	};
	struct bitproxy_t : public tmpl_multibit_proxy_t<typename array_t::reference>
	{
		bitproxy_t(typename array_t::reference byte, unsigned shift) :
			tmpl_multibit_proxy_t<typename array_t::reference>(byte, shift)
		{
		}
		bitproxy_t& operator=(unsigned u)
		{
			assert(!(u & ~this->bitmask_low_aligned()));
			this->m_byte = (this->m_byte & ~this->mask()) | (u << this->shift());
			return *this;
		}
	};
	typedef tmpl_multibit_proxy_t<typename array_t::const_reference> const_bitproxy_t;
public:
	bitproxy_t operator[](size_type segnum)
	{
		return this->template make_maskproxy<bitproxy_t>(this->a, segnum);
	}
	const_bitproxy_t operator[](size_type segnum) const
	{
		return this->template make_maskproxy<const_bitproxy_t>(this->a, segnum);
	}
};

}
#endif