/*
 * rtlsdr_experimental.h — EXPERIMENTAL RTL2832U-over-USB-Host module for the
 * ESP32-P4 sensor node (Workstream J, ESP32-P4 Sensor Node spec).
 *
 * ============================================================================
 * HARDWARE PASS REQUIRED — UNVERIFIED AGAINST REAL HARDWARE
 * ============================================================================
 * This entire module (this header + rtlsdr_experimental.c) has been written
 * from documented ESP-IDF USB Host Library API shape and the RTL2832U/R820T
 * register sequence already researched for this project in
 * frontend/src/lib/sdr.ts (a WebUSB driver, real and documented against
 * librtlsdr's public register map). It has NOT been compiled against a real
 * ESP-IDF toolchain (none is available in this environment) and has NOT run
 * against real ESP32-P4 + RTL2832U dongle hardware. Treat every register
 * value, timing constant, buffer size, and API call signature here as
 * "structurally reasoned, not verified." See the "Workstream J" section of
 * ../../README.md for the full honesty write-up, including exactly what a
 * real hardware bring-up session needs to check before this is trusted.
 *
 * Scope reminder: this is a self-contained ESP-IDF *component*, deliberately
 * kept out of `main/` so it can be dropped into Workstream I's firmware
 * project skeleton (WiFi/HTTP/BME280/presence-sensor core) without touching
 * any file that workstream owns. Integration is one line in the consuming
 * project: add this directory to EXTRA_COMPONENT_DIRS (or copy it under that
 * project's own components/) and call rtlsdr_exp_init()/rtlsdr_exp_start()
 * from wherever app_main() sets up its other sensor drivers.
 * ============================================================================
 */
#pragma once

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

#include "esp_err.h"

#ifdef __cplusplus
extern "C" {
#endif

/* ---------------------------------------------------------------------------
 * USB identification — ported 1:1 from frontend/src/lib/sdr.ts
 * (RTL2832U_VENDOR / RTL2832U_PRODUCTS / TERRATEC_VENDOR, lines ~30-34).
 *
 * sdr.ts deliberately filters WebUSB's device picker by *vendor* id only
 * (see its requestDevice() comment: "many dongles report product ids
 * outside the handful we know, so filtering by productId hides them from
 * the picker"). We mirror that: RTLSDR_EXP_KNOWN_PRODUCT_IDS below is
 * informational only (used for a startup log line), never a hard match
 * filter. Any device presenting vendor id RTL2832U or TERRATEC is treated
 * as a candidate and bring-up is attempted.
 * ------------------------------------------------------------------------ */
#define RTLSDR_EXP_VENDOR_RTL2832U 0x0BDAu
#define RTLSDR_EXP_VENDOR_TERRATEC 0x0CCDu

/* Known RTL2832U product ids (informational/logging only — see above). */
extern const uint16_t RTLSDR_EXP_KNOWN_PRODUCT_IDS[4];
#define RTLSDR_EXP_NUM_KNOWN_PRODUCT_IDS 4

/* ---------------------------------------------------------------------------
 * Configuration
 * ------------------------------------------------------------------------ */
typedef struct {
    /* Tuning defaults, applied once bring-up completes. Matches sdr.ts's
     * open(sampleRateHz = 2_048_000) default and its FM-band test tune of
     * 98 MHz — pick whatever the product actually wants to listen to. */
    uint32_t center_freq_hz;   /* e.g. 98_000_000 */
    uint32_t sample_rate_hz;   /* e.g. 2_048_000 */

    /* Bulk-IN read tuning. bulk_read_chunk_bytes MUST be a multiple of 512
     * (USB high-speed bulk max packet size) — this mirrors sdr.ts's own
     * assumption ("Length must be multiple of 512" on readSamples()).
     * UNVERIFIED: real chunk size vs. USB Host Library heap/DMA limits and
     * actual achievable throughput needs a real device. See README. */
    size_t bulk_read_chunk_bytes;    /* default suggestion: 16384 */
    size_t bulk_read_queue_depth;    /* in-flight pipelined transfers, e.g. 4 */

    /* Upstream IQ forwarding (see rtlsdr_exp_forward_iq_block() and the
     * "IQ forwarding architecture" section of the README for the reasoning
     * behind a *separate* raw-binary stream rather than reusing the JSON
     * sensor telemetry endpoint). NOTE: the backend endpoint referenced
     * here does not exist yet anywhere in this repo as of this workstream —
     * this is a client-side stub against a *proposed* shape, not a wired
     * integration. */
    const char *iq_upload_url;        /* e.g. "https://host/api/device/iq-stream" */
    const char *device_bearer_token;  /* same raw pairing token used for
                                        * the regular telemetry POST loop */
} rtlsdr_exp_config_t;

/* Fills in documented, conservative defaults. Caller still MUST set
 * iq_upload_url / device_bearer_token before starting. */
void rtlsdr_exp_config_default(rtlsdr_exp_config_t *config);

typedef struct rtlsdr_exp_handle_s *rtlsdr_exp_handle_t;

/* ---------------------------------------------------------------------------
 * Lifecycle
 * ------------------------------------------------------------------------ */

/* Allocates internal state. Does NOT touch USB hardware yet. */
esp_err_t rtlsdr_exp_init(const rtlsdr_exp_config_t *config, rtlsdr_exp_handle_t *out_handle);
esp_err_t rtlsdr_exp_deinit(rtlsdr_exp_handle_t handle);

/* Installs the USB Host Library, registers a client, and spawns the
 * background tasks that watch for a matching RTL2832U device, run the
 * init vendor-command sequence on attach, and (once bring-up succeeds)
 * start the bulk-IN read/forward loop. Non-blocking — returns once the
 * tasks are created, not once a device is found.
 *
 * UNVERIFIED beyond "this is the documented shape of the ESP-IDF USB Host
 * Library API" — see README for exactly what needs a real board to check. */
esp_err_t rtlsdr_exp_start(rtlsdr_exp_handle_t handle);

/* Stops streaming, releases the USB interface/device if held, deregisters
 * the USB Host client, and tears down the background tasks. Does NOT call
 * usb_host_uninstall() if other USB Host clients might still be active in
 * the wider firmware project (Workstream I owns whether anything else in
 * the project also uses USB host) — see README integration notes. */
esp_err_t rtlsdr_exp_stop(rtlsdr_exp_handle_t handle);

/* Best-effort retune while streaming — same caveats as sdr.ts's
 * setFrequency()/setSampleRate() (simplified PLL/resampler math, marked
 * HARDWARE PASS REQUIRED there too). */
esp_err_t rtlsdr_exp_set_frequency(rtlsdr_exp_handle_t handle, uint32_t hz);
esp_err_t rtlsdr_exp_set_sample_rate(rtlsdr_exp_handle_t handle, uint32_t hz);

/* ---------------------------------------------------------------------------
 * Observability — deliberately exposed so this experimental module can
 * report its own health (e.g. folded into the regular sensor_type registry
 * as a synthetic "sdr_status" reading) rather than fail silently.
 * ------------------------------------------------------------------------ */
typedef struct {
    bool     device_present;   /* a matching-vendor USB device is enumerated */
    bool     bring_up_ok;      /* init vendor-command sequence completed without
                                 * a control-transfer error (does NOT mean the
                                 * tuner/demod are actually producing valid IQ —
                                 * only real hardware + a spectrum check can
                                 * confirm that) */
    bool     streaming;
    uint32_t bulk_reads_ok;
    uint32_t bulk_reads_failed;
    uint32_t iq_blocks_dropped;      /* forward queue was full — see README */
    uint32_t bytes_forwarded_upstream;
    uint32_t forward_failures;
} rtlsdr_exp_stats_t;

void rtlsdr_exp_get_stats(rtlsdr_exp_handle_t handle, rtlsdr_exp_stats_t *out_stats);

#ifdef __cplusplus
}
#endif