#ifndef LIKELIHOOD_H
#define LIKELIHOOD_H

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

#define PSUP_REFLECTION_TIME 80.0

/* 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_ELECTRON 0.4
#define CHARGE_FRACTION_MUON 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

/* Maximum number of vertices to fit. */
#define MAX_VERTICES 2

typedef struct vertex {
    int id;
    double T0;
    double pos[3];
    double dir[3];
    double t0;
    double z1[10];
    double z2[10];
    size_t n;
} vertex;

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 time_pdf(double t, double mu_noise, double mu_indirect, double *mu_direct, double *mu_shower, size_t n, double *ts, double *ts_shower, double tmean, double sigma, double *ts_sigma);
double time_cdf(double t, double mu_noise, double mu_indirect, double *mu_direct, double *mu_shower, size_t n, double *ts, double *ts_shower, double tmean, double sigma, double *ts_sigma);
double nll_best(event *ev);
double nll(event *ev, vertex *v, size_t n, double dx, double dx_shower, int fast, int charge_only);

#endif