/*
This Source Code Form is subject to the
terms of the Mozilla Public License, v.
2.0. If a copy of the MPL was not
distributed with this file, You can
obtain one at
http://mozilla.org/MPL/2.0/.
*/

#pragma once

#include <string>
#include <utility>
#include <vector>

// vertical alignment (grade line) of the rail top along the chainage of a route
namespace profile
{

// point of intersection of two grades, with a parabolic vertical curve of radius R (0: none)
struct pvi
{
	double chainage{0.0};
	double elevation{0.0};
	double radius{0.0};
	bool automatic{true}; // radius follows the limits
	bool joint{false}; // placed by complete(), takes the grade over from the adjoining track
};

struct limits
{
	double grade_max{6.0}; // per mille
	double grade_switch_max{2.5}; // per mille, over switches
	double radius_factor{0.4}; // R >= k * V^2
	double radius_min{2000.0};
	double curve_threshold{2.0}; // per mille, change of grade which needs a vertical curve
	double element_min{0.0}; // m, constant grade between vertical curves
	double fixed_tolerance{0.005}; // m, allowed departure from fixed points
};

struct line
{
	std::vector<pvi> points; // ordered by chainage; the first and the last are the ends of the route
	double speed{100.0};
	limits norms;
	// at the joined ends: keep the elevation and take over the grade of the adjoining track
	bool join_start{true};
	bool join_end{true};
};

double elevation(line const &Line, double const Chainage);
// dy/ds
double grade(line const &Line, double const Chainage);
// grade of the element between points Index and Index + 1
double grade_after(line const &Line, std::size_t const Index);
double required_radius(line const &Line);
// radii of the automatic points: the required one where the change of grade needs a curve, none elsewhere
void assign_radii(line &Line);

struct curve
{
	std::size_t point{0};
	double start{0.0};
	double end{0.0};
	double tangent{0.0};
	double sagitta{0.0};
	double change{0.0}; // grade after - grade before
};
std::vector<curve> curves(line const &Line);

// radius which gives specified elevation of the curve at the point of intersection
double radius_for_sagitta(line const &Line, std::size_t const Point, double const Sagitta);

// facts about the route which the checks take into account
struct context
{
	double length{0.0};
	struct zone
	{
		double from{0.0};
		double to{0.0};
		std::string name;
	};
	std::vector<zone> switches;
	// elevations which the grade line has to keep (chainage, elevation)
	std::vector<std::pair<double, double>> fixed;
	// adjoining track at the ends; grades rise along the route
	double start_elevation{0.0}, end_elevation{0.0};
	double start_grade{0.0}, end_grade{0.0};
	bool start_joined{false}, end_joined{false};
};

// locks the joined ends, places the joint points and sets the automatic radii
void complete(line &Line, context const &Context);

struct issue
{
	bool error{false};
	int point{-1};
	double chainage{0.0};
	std::string text;
};
std::vector<issue> check(line const &Line, context const &Context);

struct recognition
{
	double grade_tolerance{0.0004};
	double minimum_length{15.0};
	double sharp_gap{2.0};
};
// grade line of existing track, from its elevations and grades sampled along the chainage
line recognize(std::vector<double> const &Chainages, std::vector<double> const &Elevations, std::vector<double> const &Grades, recognition const &Options);

struct ground_fit
{
	double tolerance{1.0}; // m, departure from the ground which doesn't yet need a change of grade
	double smoothing{20.0}; // m, length over which the ground is averaged
};
// grade line which follows the ground within the limits of Settings, with the least earthworks.
// Ground is NaN where there's none; the joined ends of the route keep the elevation of the adjoining track
line fit_ground(std::vector<double> const &Chainages, std::vector<double> const &Ground, context const &Context, line const &Settings, ground_fit const &Options);

// chainages where the paths have to end so that each of them carries a single grade or a single curve
std::vector<double> breaks(line const &Line);

std::string format_chainage(double const Chainage);

}