#pragma once

#include <stdbool.h>
#include <stdint.h>


#define blky_clamp(x, a, b) ((x) < (a)? (a): (x) > (b)? (b): (x))
#define blky_abs(x) ((x) < 0? -(x): (x))


/* ---- Sensor ----
 * calculates correl from samples sequencially */
typedef struct blky_sensor_t {
  double sum, avg, var;
  uint64_t time;

  double cov;
  double correl;
  double prev_correl;

# define BLKY_SENSOR_MAX_DUR 64
  float values[BLKY_SENSOR_MAX_DUR];
} blky_sensor_t;

void
blky_sensor_feed(
    blky_sensor_t*, const float* v, uint64_t n);

void
blky_sensor_drop(
    blky_sensor_t*, uint64_t until);


/* ---- Block ----
 * calculates probability representing how likely the block is a feature,
 * by dealing with multiple sensors */

double  /* 0~1 probability */
blky_block_estimate(
    const blky_sensor_t* sensors, uint64_t n,
    double max_var, double min_avg);


/* ---- Extractor ----
 * extracts all features from a sequence of multiple frames */
typedef struct blky_extractor_t {
  // must be filled before init()
  uint32_t block_num_x;
  uint32_t block_num_y;
  uint32_t sensor_num_block_x;
  uint32_t sensor_num_block_y;
  uint32_t samples_per_pix;
  uint32_t pix_stride;
  uint32_t utime;

  double correl_max_var;
  double correl_min_avg;

  // immutable internal params
  uint32_t block_num;
  uint32_t sensor_num_block;
  uint32_t sensor_num_whole;

  double block_w;
  double block_h;
  double sensor_interval_x;
  double sensor_interval_y;

  // mutable internal state
  uint64_t time;

  // heap objects
  uint8_t*       mem;
  blky_sensor_t* sensors;
  double*        probs;
} blky_extractor_t;

typedef struct blky_extractor_feat_t {
  uint32_t block;
  uint64_t begin;
  double   prob;
} blky_extractor_feat_t;

void
blky_extractor_init(
    blky_extractor_t* ex);

void
blky_extractor_deinit(
    blky_extractor_t* ex);

bool
blky_extractor_feed(
    blky_extractor_t* ex,
    const uint8_t* img, uint32_t w, uint32_t h, const double verts[8]);


/* ---- Image utility ---- */
void blky_image_convert_to_normalized_coord(
    const double verts[8], double* x, double* y);

uint64_t blky_image_offset(
    uint32_t w, uint32_t h, const double verts[8], double x, double y);