// firmware/lib/cv/cv.h
#pragma once
#include <stdint.h>
#include <vector>

static const int CV_W = 96;
static const int CV_H = 96;
static const int CV_PIXELS = CV_W * CV_H;

static const uint8_t CV_DIFF_THRESH = 30;
static const int CV_MIN_BLOB_PX = 64;
static const float CV_MAX_MOVE = 15.0f;
static const int CV_MAX_MISSED = 10;

// Directional counting margin: a track only counts if it spawned and is now
// both at least this far from the line (in pixels). Prevents counting blobs
// that wobble around the line or spawn on top of it. Value chosen at ~15% of
// the 96px frame: 14px ≈ the typical torso half-width overhead.
static const float CV_TRAVERSAL_MARGIN_PX = 14.0f;

// Per-direction crossing cooldown. Any same-direction crossing whose frame gap
// is strictly less than this value is dropped. At 5 fps, a value of 5 → ≈0.8s
// suppression window. Purpose: mask track churn (blob briefly drops below
// min_blob_px, track dies & respawns, re-crosses).
static const uint32_t CV_CROSSING_COOLDOWN_FRAMES = 5;

struct CVTrack {
    int   id;
    float x, y;
    float spawn_y;    // y at track creation — used for directional counting
    bool  above_line;
    bool  counted;    // fires at most once per track (one track = one trip)
    int   missed;
};

struct CVState {
    uint8_t  background[CV_PIXELS];
    bool     bg_valid;
    uint32_t last_motion_frame;
    uint32_t frame_index;
    int      next_id;
    std::vector<CVTrack> tracks;
    int entries;
    int exits;
    uint32_t last_entry_frame; // 0 = never; frame_index of last counted entry
    uint32_t last_exit_frame;  // 0 = never; frame_index of last counted exit
};

struct CVResult {
    int entries_delta;
    int exits_delta;
};

void cv_init(CVState& state);
CVResult cv_process(CVState& state, const uint8_t* frame, uint8_t line_pct);
void cv_reset_counts(CVState& state);