#ifndef LIKELIHOOD_H
#define LIKELIHOOD_H

#include "event.h"
#include <stddef.h> /* for size_t */

/* Minimum number of points in the track integral. */
#define MIN_NPOINTS 100

/* To avoid having to allocate new arrays every time we evaluate the likelihood
 * function, we just allocate static arrays with `MAX_POINTS` elements. */
#define MAX_NPOINTS 1000

/* Maximum number of PE to consider if the PMT was hit. */
#define MAX_PE 10000
/* Maximum number of PE to consider if the PMT wasn't hit.
 *
 * Note: This must be less than MAX_PE. */
#define MAX_PE_NO_HIT 10

/* To speed things up we quit calculating the probability of a hit when the
 * ratio between the current probability and the maximum probability is less
 * than 10**(-MIN_RATIO). So if MIN_RATIO is -10, that means that we ignore
 * probabilities which are 10 million times less likely than the most probable
 * value for n. */
#define MIN_RATIO -10
/* Same as above but for the "fast" likelihood calculation. */
#define MIN_RATIO_FAST -2

/* The fraction of reflected light which is detected. */
#define CHARGE_FRACTION 0.5

/* Dark rate of the PMTs (Hz).
 *
 * From pmt_response.dat in SNOMAN. */
#define DARK_RATE 1000.0
/* Single PE transit time spread (ns).
 *
 * From pmt_response.dat in SNOMAN. */
#define PMT_TTS 1.61
/* Event window (ns) */
#define GTVALID 400.0
#define BETA_MIN 0.8

/* Number of photons in the range 200 nm - 800 nm generated per MeV of energy
 * lost to radiation for electrons.
 *
 * FIXME: This is just a rough estimate, should use an energy dependent
 * quantity from simulation. */
#define PHOTONS_PER_MEV 400.0

typedef struct particle {
    int id;
    double mass;
    double range;
    double rad;
    double *x;
    double *T;
    size_t n;
    double a;
    double b;
} particle;

particle *particle_init(int id, double T0, size_t n);
double particle_get_energy(double x, particle *p);
void particle_free(particle *p);
double nll_muon(event *ev, int id, double T0, double *pos, double *dir, double t0, double *z1, double *z2, size_t n, double dx, double dx_shower, int fast);

#endif