#include "rail.h"
#include "network.h"
#include <GL/glew.h>
#include <array>
#include <collection.hpp>
#include <game/network/link.h>
#include <game/network/network.impl.h> // IWYU pragma: keep
#include <gfx/models/vertex.hpp>
#include <glm/gtx/transform.hpp>
#include <maths.h>
#include <stdexcept>
#include <utility>
#include <vector>

template class NetworkOf<RailLink>;

constexpr auto RAIL_CROSSSECTION_VERTICES {5U};
constexpr glm::vec3 RAIL_HEIGHT {0, 0, .25F};

RailLinks::RailLinks() : NetworkOf<RailLink> {"rails.jpg"} { }
void
RailLinks::tick(TickDuration)
{
}

std::shared_ptr<RailLink>
RailLinks::addLinksBetween(glm::vec3 start, glm::vec3 end)
{
	auto node1ins = newNodeAt(start), node2ins = newNodeAt(end);
	if (node1ins.second && node2ins.second) {
		// Both nodes are new, direct link, easy
		return addLink<RailLinkStraight>(start, end);
	}
	if (node1ins.second && !node2ins.second) {
		// node1 is new, node2 exists, but we build from existing outwards
		std::swap(node1ins, node2ins);
		std::swap(start, end);
	}
	// Find start link/end - opposite entry dir to existing link; so pi +...
	const auto findDir = [this](const auto & n) {
		for (const auto & l : links.objects) {
			for (const auto & e : l->ends) {
				// cppcheck-suppress useStlAlgorithm
				if (e.node == n) {
					return e.dir;
				}
			}
		}
		throw std::runtime_error("Node exists but couldn't find it");
	};
	float dir = pi + findDir(node1ins.first);
	if (dir == vector_yaw(end - start)) {
		return addLink<RailLinkStraight>(start, end);
	}
	const glm::vec2 flatStart {!start}, flatEnd {!end};
	if (!node2ins.second) {
		auto midheight = [&](auto mid) {
			const auto sm = glm::distance(flatStart, mid), em = glm::distance(flatEnd, mid);
			return start.z + ((end.z - start.z) * (sm / (sm + em)));
		};
		float dir2 = pi + findDir(node2ins.first);
		if (const auto radii = find_arcs_radius(flatStart, dir, flatEnd, dir2); radii.first < radii.second) {
			const auto radius {radii.first};
			const auto c1 = flatStart + sincosf(dir + half_pi) * radius;
			const auto c2 = flatEnd + sincosf(dir2 + half_pi) * radius;
			const auto mid = (c1 + c2) / 2.F;
			const auto midh = mid ^ midheight(mid);
			addLink<RailLinkCurve>(start, midh, c1);
			return addLink<RailLinkCurve>(end, midh, c2);
		}
		else {
			const auto radius {radii.second};
			const auto c1 = flatStart + sincosf(dir - half_pi) * radius;
			const auto c2 = flatEnd + sincosf(dir2 - half_pi) * radius;
			const auto mid = (c1 + c2) / 2.F;
			const auto midh = mid ^ midheight(mid);
			addLink<RailLinkCurve>(midh, start, c1);
			return addLink<RailLinkCurve>(midh, end, c2);
		}
	}
	const auto diff {end - start};
	const auto vy {vector_yaw(diff)};
	const auto n2ed {(vy * 2) - dir - pi};
	const auto centre {find_arc_centre(flatStart, dir, flatEnd, n2ed)};

	if (centre.second) { // right hand arc
		std::swap(start, end);
	}
	return addLink<RailLinkCurve>(start, end, centre.first);
}

MeshPtr
RailLink::defaultMesh(const std::span<Vertex> vertices)
{
	std::vector<unsigned int> indices;
	for (auto n = RAIL_CROSSSECTION_VERTICES; n < vertices.size(); n += 1) {
		indices.push_back(n - RAIL_CROSSSECTION_VERTICES);
		indices.push_back(n);
	}

	return std::make_unique<Mesh>(vertices, indices, GL_TRIANGLE_STRIP);
}

void
RailLink::render(const Shader &) const
{
	mesh->Draw();
}

constexpr const std::array<std::pair<glm::vec3, float>, RAIL_CROSSSECTION_VERTICES> railCrossSection {{
		//   ___________
		// _/           \_
		//  left to right
		{{-1.9F, 0.F, 0.F}, 0.F},
		{{-.608F, 0.F, RAIL_HEIGHT.z}, 0.34F},
		{{0, 0.F, RAIL_HEIGHT.z * .7F}, 0.5F},
		{{.608F, 0.F, RAIL_HEIGHT.z}, 0.66F},
		{{1.9F, 0.F, 0.F}, 1.F},
}};
constexpr auto sleepers {5.F}; // There are 5 repetitions of sleepers in the texture

inline auto
round_sleepers(const float v)
{
	return round_frac(v, sleepers);
}

RailLinkStraight::RailLinkStraight(const NodePtr & a, const NodePtr & b) : RailLinkStraight(a, b, b->pos - a->pos) { }

RailLinkStraight::RailLinkStraight(NodePtr a, NodePtr b, const glm::vec3 & diff) :
	Link({std::move(a), vector_yaw(diff)}, {std::move(b), vector_yaw(-diff)}, glm::length(diff))
{
	if (glGenVertexArrays) {
		std::vector<Vertex> vertices;
		vertices.reserve(2 * railCrossSection.size());
		const auto len = round_sleepers(length / 2.F);
		const auto e {flat_orientation(diff)};
		for (int ei : {1, 0}) {
			const auto trans {glm::translate(ends[ei].node->pos) * e};
			for (const auto & rcs : railCrossSection) {
				const glm::vec3 m {(trans * glm::vec4 {rcs.first, 1})};
				vertices.emplace_back(m, glm::vec2 {rcs.second, len * static_cast<float>(ei)}, up);
			}
		}
		mesh = defaultMesh(vertices);
	}
}

RailLinkCurve::RailLinkCurve(const NodePtr & a, const NodePtr & b, glm::vec2 c) :
	RailLinkCurve(a, b, c ^ a->pos.z, {!c, a->pos, b->pos})
{
}

RailLinkCurve::RailLinkCurve(const NodePtr & a, const NodePtr & b, glm::vec3 c, const Arc arc) :
	Link({a, normalize(arc.first + half_pi)}, {b, normalize(arc.second - half_pi)},
			(glm::length(a->pos - c)) * arc_length(arc)),
	LinkCurve {c, glm::length(ends[0].node->pos - c), arc}
{
	if (glGenVertexArrays) {
		const auto & e0p {ends[0].node->pos};
		const auto & e1p {ends[1].node->pos};
		const auto slength = round_sleepers(length / 2.F);
		const auto segs = std::round(15.F * slength / std::pow(radius, 0.7F));
		const auto step {glm::vec3 {arc_length(arc), e1p.z - e0p.z, slength} / segs};
		const auto trans {glm::translate(centreBase)};

		auto segCount = std::lround(segs);
		std::vector<Vertex> vertices;
		vertices.reserve((segCount + 1) * railCrossSection.size());
		for (glm::vec3 swing = {arc.first, centreBase.z - e0p.z, 0.F}; segCount >= 0; swing += step, --segCount) {
			const auto t {
					trans * glm::rotate(half_pi - swing.x, up) * glm::translate(glm::vec3 {radius, 0.F, swing.y})};
			for (const auto & rcs : railCrossSection) {
				const glm::vec3 m {(t * glm::vec4 {rcs.first, 1})};
				vertices.emplace_back(m, glm::vec2 {rcs.second, swing.z}, up);
			}
		}
		mesh = defaultMesh(vertices);
	}
}

glm::vec3
RailLink::vehiclePositionOffset() const
{
	return RAIL_HEIGHT;
}