/**
 * @file edge_processing.h
 * @brief ADR-039 Edge Intelligence — dual-core CSI processing pipeline.
 *
 * Core 0 (WiFi): Produces CSI frames into a lock-free SPSC ring buffer.
 * Core 1 (DSP):  Consumes frames, runs signal processing, extracts vitals.
 *
 * Features:
 *   - Biquad IIR bandpass filters for breathing (0.1-0.5 Hz) and heart rate (0.8-2.0 Hz)
 *   - Phase unwrapping and Welford running statistics
 *   - Top-K subcarrier selection by variance
 *   - Presence detection with adaptive threshold calibration
 *   - Vital signs: breathing rate, heart rate (zero-crossing BPM)
 *   - Fall detection (phase acceleration exceeds threshold)
 *   - Delta compression (XOR + RLE) for bandwidth reduction
 *   - Multi-person vitals via subcarrier group clustering
 *   - 32-byte vitals packet (magic 0xC5110002) for server-side parsing
 */

#ifndef EDGE_PROCESSING_H
#define EDGE_PROCESSING_H

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

/* ---- Magic numbers ---- */
#define EDGE_VITALS_MAGIC     0xC5110002  /**< Vitals packet magic. */
#define EDGE_COMPRESSED_MAGIC 0xC5110003  /**< Compressed frame magic. */

/* ---- Buffer sizes ---- */
#define EDGE_RING_SLOTS       16    /**< SPSC ring buffer slots (power of 2). */
#define EDGE_MAX_IQ_BYTES     1024  /**< Max I/Q payload per slot. */
#define EDGE_PHASE_HISTORY_LEN 256  /**< Phase history buffer depth. */
#define EDGE_TOP_K            8     /**< Top-K subcarriers to track. */
#define EDGE_MAX_SUBCARRIERS  128   /**< Max subcarriers per frame. */

/* ---- Multi-person ---- */
#define EDGE_MAX_PERSONS      4     /**< Max simultaneous persons. */

/* ---- Calibration ---- */
#define EDGE_CALIB_FRAMES     1200  /**< Frames for adaptive calibration (~60s at 20 Hz). */
#define EDGE_CALIB_SIGMA_MULT 3.0f  /**< Threshold = mean + 3*sigma of ambient. */

/* ---- SPSC ring buffer slot ---- */
typedef struct {
    uint8_t  iq_data[EDGE_MAX_IQ_BYTES]; /**< Raw I/Q bytes from CSI callback. */
    uint16_t iq_len;                     /**< Actual I/Q data length. */
    int8_t   rssi;                       /**< RSSI from rx_ctrl. */
    uint8_t  channel;                    /**< WiFi channel. */
    uint32_t timestamp_us;               /**< Microsecond timestamp. */
} edge_ring_slot_t;

/* ---- SPSC ring buffer ---- */
typedef struct {
    edge_ring_slot_t slots[EDGE_RING_SLOTS];
    volatile uint32_t head;  /**< Written by producer (Core 0). */
    volatile uint32_t tail;  /**< Written by consumer (Core 1). */
} edge_ring_buf_t;

/* ---- Biquad IIR filter state ---- */
typedef struct {
    float b0, b1, b2;  /**< Numerator coefficients. */
    float a1, a2;       /**< Denominator coefficients (a0 = 1). */
    float x1, x2;       /**< Input delay line. */
    float y1, y2;       /**< Output delay line. */
} edge_biquad_t;

/* ---- Welford running statistics ---- */
typedef struct {
    double mean;
    double m2;
    uint32_t count;
} edge_welford_t;

/* ---- Per-person vitals state (multi-person mode) ---- */
typedef struct {
    float    phase_history[EDGE_PHASE_HISTORY_LEN];
    uint16_t history_len;
    uint16_t history_idx;
    float    breathing_bpm;
    float    heartrate_bpm;
    uint8_t  subcarrier_idx;  /**< Which subcarrier group this person tracks. */
    bool     active;
} edge_person_vitals_t;

/* ---- Vitals packet (32 bytes, wire format) ---- */
typedef struct __attribute__((packed)) {
    uint32_t magic;          /**< EDGE_VITALS_MAGIC = 0xC5110002. */
    uint8_t  node_id;        /**< ESP32 node identifier. */
    uint8_t  flags;          /**< Bit0=presence, Bit1=fall, Bit2=motion. */
    uint16_t breathing_rate; /**< BPM * 100 (fixed-point). */
    uint32_t heartrate;      /**< BPM * 10000 (fixed-point). */
    int8_t   rssi;           /**< Latest RSSI. */
    uint8_t  n_persons;      /**< Number of detected persons (multi-person). */
    uint8_t  reserved[2];
    float    motion_energy;  /**< Phase variance / motion metric. */
    float    presence_score; /**< Presence detection score. */
    uint32_t timestamp_ms;   /**< Milliseconds since boot. */
    uint32_t reserved2;      /**< Reserved for future use. */
} edge_vitals_pkt_t;

_Static_assert(sizeof(edge_vitals_pkt_t) == 32, "vitals packet must be 32 bytes");

/* ---- Edge configuration (from NVS) ---- */
typedef struct {
    uint8_t  tier;           /**< Processing tier: 0=raw, 1=basic, 2=full. */
    float    presence_thresh;/**< Presence detection threshold (0 = auto-calibrate). */
    float    fall_thresh;    /**< Fall detection threshold (phase accel, rad/s^2). */
    uint16_t vital_window;   /**< Phase history window for BPM estimation. */
    uint16_t vital_interval_ms; /**< Vitals packet send interval in ms. */
    uint8_t  top_k_count;    /**< Number of top subcarriers to track. */
    uint8_t  power_duty;     /**< Power duty cycle percentage (10-100). */
} edge_config_t;

/**
 * Initialize the edge processing pipeline.
 * Creates the SPSC ring buffer and starts the DSP task on Core 1.
 *
 * @param cfg  Edge configuration (from NVS or defaults).
 * @return ESP_OK on success.
 */
esp_err_t edge_processing_init(const edge_config_t *cfg);

/**
 * Enqueue a CSI frame from the WiFi callback (Core 0).
 * Lock-free SPSC push — safe to call from ISR context.
 *
 * @param iq_data   Raw I/Q data from wifi_csi_info_t.buf.
 * @param iq_len    Length of I/Q data in bytes.
 * @param rssi      RSSI from rx_ctrl.
 * @param channel   WiFi channel number.
 * @return true if enqueued, false if ring buffer is full (frame dropped).
 */
bool edge_enqueue_csi(const uint8_t *iq_data, uint16_t iq_len,
                      int8_t rssi, uint8_t channel);

/**
 * Get the latest vitals packet (thread-safe copy).
 *
 * @param pkt  Output vitals packet.
 * @return true if valid vitals data is available.
 */
bool edge_get_vitals(edge_vitals_pkt_t *pkt);

/**
 * Get multi-person vitals array.
 *
 * @param persons   Output array (must be EDGE_MAX_PERSONS elements).
 * @param n_active  Output: number of active persons.
 */
void edge_get_multi_person(edge_person_vitals_t *persons, uint8_t *n_active);

/**
 * Get pointer to the phase history ring buffer and its state.
 * Used by WASM runtime (ADR-040) to expose phase history to modules.
 *
 * @param out_buf     Output: pointer to phase history array.
 * @param out_len     Output: number of valid entries.
 * @param out_idx     Output: current write index.
 */
void edge_get_phase_history(const float **out_buf, uint16_t *out_len,
                            uint16_t *out_idx);

/**
 * Get per-subcarrier Welford variance array.
 * Used by WASM runtime (ADR-040) to expose variances to modules.
 *
 * @param out_variances  Output array (must be EDGE_MAX_SUBCARRIERS elements).
 * @param n_subcarriers  Number of subcarriers to fill.
 */
void edge_get_variances(float *out_variances, uint16_t n_subcarriers);

#endif /* EDGE_PROCESSING_H */