/*
    Copyright (C) 2014-2021 Carl Hetherington <cth@carlh.net>

    This file is part of DCP-o-matic.

    DCP-o-matic is free software; you can redistribute it and/or modify
    it under the terms of the GNU General Public License as published by
    the Free Software Foundation; either version 2 of the License, or
    (at your option) any later version.

    DCP-o-matic is distributed in the hope that it will be useful,
    but WITHOUT ANY WARRANTY; without even the implied warranty of
    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
    GNU General Public License for more details.

    You should have received a copy of the GNU General Public License
    along with DCP-o-matic.  If not, see <http://www.gnu.org/licenses/>.

*/


/** @file  src/lib/dcpomatic_time.h
 *  @brief Types to describe time.
 */


#ifndef DCPOMATIC_TIME_H
#define DCPOMATIC_TIME_H


#include "dcpomatic_assert.h"
#include "frame_rate_change.h"
#include <dcp/types.h>
#include <boost/optional.hpp>
#include <stdint.h>
#include <cmath>
#include <cstdio>
#include <iomanip>
#include <list>
#include <ostream>


struct dcpomatic_time_ceil_test;
struct dcpomatic_time_floor_test;


namespace dcpomatic {


class HMSF
{
public:
	HMSF() {}

	HMSF(int h_, int m_, int s_, int f_)
		: h(h_)
		, m(m_)
		, s(s_)
		, f(f_)
	{}

	int h = 0;
	int m = 0;
	int s = 0;
	int f = 0;
};


bool operator<=(HMSF const& a, HMSF const& b);


/** A time in seconds, expressed as a number scaled up by Time::HZ.  We want two different
 *  versions of this class, dcpomatic::ContentTime and dcpomatic::DCPTime, and we want it to be impossible to
 *  convert implicitly between the two.  Hence there's this template hack.  I'm not
 *  sure if it's the best way to do it.
 *
 *  S is the name of `this' class and O is its opposite (see the typedefs below).
 */
template <class S, class O>
class Time
{
public:
	Time() = default;

	typedef int64_t Type;

	explicit Time(Type t)
		: _t(t)
	{}

	explicit Time(Type n, Type d)
		: _t(n * HZ / d)
	{}

	/* Explicit conversion from type O */
	Time(Time<O, S> d, FrameRateChange f);

	/** @param hmsf Hours, minutes, seconds, frames.
	 *  @param fps Frame rate
	 */
	Time(HMSF const& hmsf, float fps) {
		*this = from_seconds(hmsf.h * 3600)
			+ from_seconds(hmsf.m * 60)
			+ from_seconds(hmsf.s)
			+ from_frames(hmsf.f, fps);
	}

	Type get() const {
		return _t;
	}

	bool operator<(Time<S, O> const & o) const {
		return _t < o._t;
	}

	bool operator<=(Time<S, O> const & o) const {
		return _t <= o._t;
	}

	bool operator==(Time<S, O> const & o) const {
		return _t == o._t;
	}

	bool operator!=(Time<S, O> const & o) const {
		return _t != o._t;
	}

	bool operator>=(Time<S, O> const & o) const {
		return _t >= o._t;
	}

	bool operator>(Time<S, O> const & o) const {
		return _t > o._t;
	}

	Time<S, O> operator+(Time<S, O> const & o) const {
		return Time<S, O>(_t + o._t);
	}

	Time<S, O> & operator+=(Time<S, O> const & o) {
		_t += o._t;
		return *this;
	}

	Time<S, O> operator-() const {
		return Time<S, O>(-_t);
	}

	Time<S, O> operator-(Time<S, O> const & o) const {
		return Time<S, O>(_t - o._t);
	}

	Time<S, O> & operator-=(Time<S, O> const & o) {
		_t -= o._t;
		return *this;
	}

	Time<S, O> operator*(int o) const {
		return Time<S, O>(_t * o);
	}

	Time<S, O> operator/(int o) const {
		return Time<S, O>(_t / o);
	}

	/** Round up to the nearest sampling interval
	 *  at some sampling rate.
	 *  @param r Sampling rate.
	 */
	Time<S, O> ceil(double r) const {
		return Time<S, O>(llrint(HZ * frames_ceil(r) / r));
	}

	Time<S, O> floor(double r) const {
		return Time<S, O>(llrint(HZ * frames_floor(r) / r));
	}

	Time<S, O> round(double r) const {
		return Time<S, O>(llrint(HZ * frames_round(r) / r));
	}

	Time<S, O> round(dcp::Fraction r) const {
		return Time<S, O>(llrint(HZ * frames_round(r) * r.denominator / r.numerator));
	}

	double seconds() const {
		return double(_t) / HZ;
	}

	Time<S, O> abs() const {
		return Time<S, O>(std::abs(_t));
	}

	template <typename T>
	int64_t frames_round(T r) const {
		/* We must cast to double here otherwise if T is integer
		   the calculation will round down before we get the chance
		   to llrint().
		*/
		return llrint(_t * double(r) / HZ);
	}

	int64_t frames_round(dcp::Fraction r) const {
		/* We must cast to double here otherwise if T is integer
		   the calculation will round down before we get the chance
		   to llrint().
		*/
		return llrint(_t * double(r.numerator) / (HZ * r.denominator));
	}

	template <typename T>
	int64_t frames_floor(T r) const {
		return ::floor(_t * r / HZ);
	}

	int64_t frames_floor(dcp::Fraction r) const {
		return ::floor(_t * r.numerator / (HZ * r.denominator));
	}

	template <typename T>
	int64_t frames_ceil(T r) const {
		/* We must cast to double here otherwise if T is integer
		   the calculation will round down before we get the chance
		   to ceil().
		*/
		return ::ceil(_t * double(r) / HZ);
	}

	/** Split a time into hours, minutes, seconds and frames.
	 *  @param r Frames per second.
	 *  @return Split time.
	 */
	template <typename T>
	HMSF split(T r) const
	{
		/* Do this calculation with frames so that we can round
		   to a frame boundary at the start rather than the end.
		*/
		auto ff = frames_round(r);
		HMSF hmsf;

		hmsf.h = ff / (3600 * r);
		ff -= static_cast<int64_t>(hmsf.h) * 3600 * r;
		hmsf.m = ff / (60 * r);
		ff -= static_cast<int64_t>(hmsf.m) * 60 * r;
		hmsf.s = ff / r;
		ff -= static_cast<int64_t>(hmsf.s) * r;

		hmsf.f = static_cast<int>(ff);
		return hmsf;
	}

	template <typename T>
	std::string timecode(T r) const {
		auto hmsf = split(r);

		char buffer[128];
		snprintf(buffer, sizeof(buffer), "%02d:%02d:%02d:%02d", hmsf.h, hmsf.m, hmsf.s, hmsf.f);
		return buffer;
	}

	static Time<S, O> from_seconds(double s) {
		return Time<S, O>(llrint(s * HZ));
	}

	template <class T>
	static Time<S, O> from_frames(int64_t f, T r) {
		DCPOMATIC_ASSERT(r > 0);
		return Time<S, O>(f * HZ / r);
	}

	static Time<S, O> from_frames(int64_t f, dcp::Fraction r) {
		DCPOMATIC_ASSERT(r.numerator > 0);
		return Time<S, O>(f * HZ * r.denominator / r.numerator);
	}

	static Time<S, O> delta() {
		return Time<S, O>(1);
	}

	static Time<S, O> min() {
		return Time<S, O>(-INT64_MAX);
	}

	static Time<S, O> max() {
		return Time<S, O>(INT64_MAX);
	}

	static const int HZ = 96000;

private:
	friend struct ::dcpomatic_time_ceil_test;
	friend struct ::dcpomatic_time_floor_test;

	Type _t = 0;
};


class ContentTimeDifferentiator {};
class DCPTimeDifferentiator {};


/* Specializations for the two allowed explicit conversions */

template<>
Time<ContentTimeDifferentiator, DCPTimeDifferentiator>::Time(Time<DCPTimeDifferentiator, ContentTimeDifferentiator> d, FrameRateChange f);

template<>
Time<DCPTimeDifferentiator, ContentTimeDifferentiator>::Time(Time<ContentTimeDifferentiator, DCPTimeDifferentiator> d, FrameRateChange f);


/** Time relative to the start or position of a piece of content in its native frame rate */
typedef Time<ContentTimeDifferentiator, DCPTimeDifferentiator> ContentTime;
/** Time relative to the start of the output DCP in its frame rate */
typedef Time<DCPTimeDifferentiator, ContentTimeDifferentiator> DCPTime;

template <class T>
class TimePeriod
{
public:
	TimePeriod() {}

	TimePeriod(T f, T t)
		: from(f)
		, to(t)
	{}

	/** start time of sampling interval that the period is from */
	T from;
	/** start time of next sampling interval after the period */
	T to;

	T duration() const {
		return to - from;
	}

	TimePeriod<T> operator+(T const & o) const {
		return TimePeriod<T>(from + o, to + o);
	}

	boost::optional<TimePeriod<T>> overlap(TimePeriod<T> const & other) const {
		T const max_from = std::max(from, other.from);
		T const min_to = std::min(to, other.to);

		if (max_from >= min_to) {
			return {};
		}

		return TimePeriod<T>(max_from, min_to);
	}

	bool contains (T const & other) const {
		return(from <= other && other < to);
	}

	bool operator<(TimePeriod<T> const & o) const {
		if (from != o.from) {
			return from < o.from;
		}
		return to < o.to;
	}

	bool operator==(TimePeriod<T> const & other) const {
		return from == other.from && to == other.to;
	}

	bool operator!=(TimePeriod<T> const & other) const {
		return !(*this == other);
	}
};


/** @param A Period which is subtracted from.
 *  @param B Periods to subtract from `A', must be in ascending order of start time and must not overlap.
 */
template <class T>
std::list<TimePeriod<T>> subtract(TimePeriod<T> A, std::list<TimePeriod<T>> const & B)
{
	std::list<TimePeriod<T>> result;
	result.push_back(A);

	for (auto i: B) {
		std::list<TimePeriod<T>> new_result;
		for (auto j: result) {
			auto ov = i.overlap(j);
			if (ov) {
				if (*ov == i) {
					/* A contains all of B */
					if (i.from != j.from) {
						new_result.push_back(TimePeriod<T>(j.from, i.from));
					}
					if (i.to != j.to) {
						new_result.push_back(TimePeriod<T>(i.to, j.to));
					}
				} else if (*ov == j) {
					/* B contains all of A */
				} else if (i.from < j.from) {
					/* B overlaps start of A */
					new_result.push_back(TimePeriod<T>(i.to, j.to));
				} else if (i.to > j.to) {
					/* B overlaps end of A */
					new_result.push_back(TimePeriod<T>(j.from, i.from));
				}
			} else {
				new_result.push_back(j);
			}
		}
		result = new_result;
	}

	return result;
}


typedef TimePeriod<ContentTime> ContentTimePeriod;
typedef TimePeriod<DCPTime> DCPTimePeriod;


DCPTime min(DCPTime a, DCPTime b);
DCPTime max(DCPTime a, DCPTime b);
ContentTime min(ContentTime a, ContentTime b);
ContentTime max(ContentTime a, ContentTime b);
std::string to_string(ContentTime t);
std::string to_string(DCPTime t);
std::string to_string(DCPTimePeriod p);


}


#endif