#pragma once

/*
 * zebra -- volume-modulated modem over PulseAudio sink inputs
 *
 * Firefox exposes each tab as a named sink input in the PulseAudio mixer.
 * A <video> element keeps audio flowing so the tab stays visible in
 * pavucontrol. The C clients modulate/read that sink's volume as the
 * signal carrier.
 *
 * Wire format (UART):
 *   idle  = MARK  (high volume, ZEBRA_VOL_MARK %)
 *   start = SPACE (low volume,  ZEBRA_VOL_SPACE %)  -- falling edge triggers rx
 *   data  = 8 bits LSB-first, 0=SPACE 1=MARK
 *   stop  = MARK
 *   frame = 10 symbols per byte
 *
 * 101 discrete levels (0–100%) available — "101 dalmatians".
 * Binary encoding uses two far-apart levels for maximum noise margin.
 */

#include <stdint.h>
#include <pulse/pulseaudio.h>

/* ------------------------------------------------------------------ *
 * signal constants                                                      *
 * ------------------------------------------------------------------ */
#define ZEBRA_VOL_MARK       80     /* % — logic-1 / idle / stop bit  */
#define ZEBRA_VOL_SPACE      20     /* % — logic-0 / start bit        */
#define ZEBRA_VOL_THRESHOLD  50     /* % — bit decision boundary      */
#define ZEBRA_DALMATIANS    101     /* discrete volume steps: 0–100   */

/* ------------------------------------------------------------------ *
 * baud rate limits                                                     *
 * ------------------------------------------------------------------ */
#define ZEBRA_BAUD_DEFAULT   10
#define ZEBRA_BAUD_MIN        1
#define ZEBRA_BAUD_MAX   100000

/* ------------------------------------------------------------------ *
 * handshake / auto-negotiation                                         *
 * ------------------------------------------------------------------ */
#define ZEBRA_BAUD_HANDSHAKE    50   /* fixed baud for negotiation phase  */
#define ZEBRA_HS_MAGIC_0      0x5A   /* 'Z'                               */
#define ZEBRA_HS_MAGIC_1      0x42   /* 'B'                               */
#define ZEBRA_HS_TYPE_OFFER   0x01   /* RX→TX: here is my max baud        */
#define ZEBRA_HS_FRAME_LEN       6   /* magic(2) type(1) baud_le(2) xor(1)*/
#define ZEBRA_HS_SETTLE_MS     500   /* quiet gap after handshake         */
#define ZEBRA_HS_TYPE_READY   0x02   /* RX→TX: receive loop is active     */
#define ZEBRA_HS_READY_WAIT   5000   /* ms TX waits for READY after OFFER */

/* ------------------------------------------------------------------ *
 * types                                                                *
 * ------------------------------------------------------------------ */

/* one PulseAudio sink input entry */
typedef struct {
    uint32_t index;
    char     name[256];
    char     app_name[128];
    uint8_t  volume_pct;    /* 0–100 */
    uint8_t  channels;
} zebra_sink_t;

/* PulseAudio connection state */
typedef struct {
    pa_threaded_mainloop *loop;
    pa_context           *ctx;
} zebra_pulse_t;

/* ------------------------------------------------------------------ *
 * pulse.c: PulseAudio interface                                        *
 * ------------------------------------------------------------------ */

/* connect to the default PulseAudio server; returns 0 on success */
int  zebra_pulse_connect(zebra_pulse_t *z, const char *app_name);
void zebra_pulse_disconnect(zebra_pulse_t *z);

/* enumerate all sink inputs; returns count or -1 */
int  zebra_list_sinks(zebra_pulse_t *z, zebra_sink_t *buf, int max);

/* find first sink input whose name or app_name contains match */
int  zebra_find_sink(zebra_pulse_t *z, const char *match, zebra_sink_t *out);

/* get/set volume percent (0–100); returns 0 on success */
int  zebra_get_volume(zebra_pulse_t *z, uint32_t sink_index, uint8_t *pct);
int  zebra_set_volume(zebra_pulse_t *z, uint32_t sink_index, uint8_t pct);

/* fast TX path: caller supplies channel count, waits for PA confirmation */
int  zebra_set_volume_fast(zebra_pulse_t *z, uint32_t sink_index,
                            uint8_t channels, uint8_t pct);

/* fire-and-forget TX: enqueues volume command, returns immediately.
 * PA processes async — symbol timing governed entirely by clock_nanosleep. */
int  zebra_set_volume_noack(zebra_pulse_t *z, uint32_t sink_index,
                             uint8_t channels, uint8_t pct);

/* ------------------------------------------------------------------ *
 * Battle Toads: per-channel stereo API                                 *
 * ------------------------------------------------------------------ */

/* Read L and R channel volumes independently (single PA IPC call).
 * Falls back: if sink is mono, both *left and *right get the same value. */
int  zebra_get_volume_lr(zebra_pulse_t *z, uint32_t sink_index,
                          uint8_t *left, uint8_t *right);

/* Fire-and-forget: set L and R to different volumes in one PA call. */
int  zebra_set_volume_lr_noack(zebra_pulse_t *z, uint32_t sink_index,
                                uint8_t left, uint8_t right);

/* ------------------------------------------------------------------ *
 * inline modem helpers                                                 *
 * ------------------------------------------------------------------ */

static inline uint8_t zebra_bit_to_vol(int bit) {
    return (uint8_t)(bit ? ZEBRA_VOL_MARK : ZEBRA_VOL_SPACE);
}

/* returns 0, 1, or -1 (exactly on threshold — ambiguous) */
static inline int zebra_vol_to_bit(uint8_t vol) {
    if (vol > ZEBRA_VOL_THRESHOLD) return 1;
    if (vol < ZEBRA_VOL_THRESHOLD) return 0;
    return -1;
}