#include "digital_sequence.h"
#include "digital_signal_i.h"

#include <furi.h>
#include <furi_hal_bus.h>

#include <stm32wbxx_ll_dma.h>
#include <stm32wbxx_ll_tim.h>

/**
 * To enable debug output on an additional pin, set DIGITAL_SIGNAL_DEBUG_OUTPUT_PIN to the required
 * GpioPin variable. It can be passed at compile time via the --extra-define fbt switch.
 * NOTE: This pin must be on the same GPIO port as the main pin.
 *
 * Example:
 * ./fbt --extra-define=DIGITAL_SIGNAL_DEBUG_OUTPUT_PIN=gpio_ext_pb3
 */

#define TAG "DigitalSequence"

/* Special value used to indicate the end of DMA ring buffer. */
#define DIGITAL_SEQUENCE_TIMER_MAX 0xFFFFFFFFUL

/* Time to wait in loops before returning */
#define DIGITAL_SEQUENCE_LOCK_WAIT_MS 10UL
#define DIGITAL_SEQUENCE_LOCK_WAIT_TICKS (DIGITAL_SEQUENCE_LOCK_WAIT_MS * 1000 * 64)

#define DIGITAL_SEQUENCE_GPIO_BUFFER_SIZE 2

/* Maximum capacity of the DMA ring buffer. */
#define DIGITAL_SEQUENCE_RING_BUFFER_SIZE 128

#define DIGITAL_SEQUENCE_RING_BUFFER_MIN_FREE_SIZE 2

/* Maximum amount of registered signals. */
#define DIGITAL_SEQUENCE_BANK_SIZE 32

typedef enum {
    DigitalSequenceStateIdle,
    DigitalSequenceStateActive,
} DigitalSequenceState;

typedef struct {
    uint32_t data[DIGITAL_SEQUENCE_RING_BUFFER_SIZE];
    uint32_t write_pos;
    uint32_t read_pos;
} DigitalSequenceRingBuffer;

typedef uint32_t DigitalSequenceGpioBuffer[DIGITAL_SEQUENCE_GPIO_BUFFER_SIZE];

typedef const DigitalSignal* DigitalSequenceSignalBank[DIGITAL_SEQUENCE_BANK_SIZE];

struct DigitalSequence {
    const GpioPin* gpio;

    uint32_t size;
    uint32_t max_size;
    uint8_t* data;

    LL_DMA_InitTypeDef dma_config_gpio;
    LL_DMA_InitTypeDef dma_config_timer;

    DigitalSequenceGpioBuffer gpio_buf;
    DigitalSequenceRingBuffer timer_buf;
    DigitalSequenceSignalBank signals;
    DigitalSequenceState state;
};

DigitalSequence* digital_sequence_alloc(uint32_t size, const GpioPin* gpio) {
    furi_assert(size);
    furi_assert(gpio);

    DigitalSequence* sequence = malloc(sizeof(DigitalSequence));

    sequence->gpio = gpio;
    sequence->max_size = size;

    sequence->data = malloc(sequence->max_size);

    sequence->dma_config_gpio.PeriphOrM2MSrcAddress = (uint32_t)&gpio->port->BSRR;
    sequence->dma_config_gpio.MemoryOrM2MDstAddress = (uint32_t)sequence->gpio_buf;
    sequence->dma_config_gpio.Direction = LL_DMA_DIRECTION_MEMORY_TO_PERIPH;
    sequence->dma_config_gpio.Mode = LL_DMA_MODE_CIRCULAR;
    sequence->dma_config_gpio.PeriphOrM2MSrcIncMode = LL_DMA_PERIPH_NOINCREMENT;
    sequence->dma_config_gpio.MemoryOrM2MDstIncMode = LL_DMA_MEMORY_INCREMENT;
    sequence->dma_config_gpio.PeriphOrM2MSrcDataSize = LL_DMA_PDATAALIGN_WORD;
    sequence->dma_config_gpio.MemoryOrM2MDstDataSize = LL_DMA_MDATAALIGN_WORD;
    sequence->dma_config_gpio.NbData = DIGITAL_SEQUENCE_GPIO_BUFFER_SIZE;
    sequence->dma_config_gpio.PeriphRequest = LL_DMAMUX_REQ_TIM2_UP;
    sequence->dma_config_gpio.Priority = LL_DMA_PRIORITY_VERYHIGH;

    sequence->dma_config_timer.PeriphOrM2MSrcAddress = (uint32_t)&TIM2->ARR;
    sequence->dma_config_timer.MemoryOrM2MDstAddress = (uint32_t)sequence->timer_buf.data;
    sequence->dma_config_timer.Direction = LL_DMA_DIRECTION_MEMORY_TO_PERIPH;
    sequence->dma_config_timer.Mode = LL_DMA_MODE_CIRCULAR;
    sequence->dma_config_timer.PeriphOrM2MSrcIncMode = LL_DMA_PERIPH_NOINCREMENT;
    sequence->dma_config_timer.MemoryOrM2MDstIncMode = LL_DMA_MEMORY_INCREMENT;
    sequence->dma_config_timer.PeriphOrM2MSrcDataSize = LL_DMA_PDATAALIGN_WORD;
    sequence->dma_config_timer.MemoryOrM2MDstDataSize = LL_DMA_MDATAALIGN_WORD;
    sequence->dma_config_timer.NbData = DIGITAL_SEQUENCE_RING_BUFFER_SIZE;
    sequence->dma_config_timer.PeriphRequest = LL_DMAMUX_REQ_TIM2_UP;
    sequence->dma_config_timer.Priority = LL_DMA_PRIORITY_HIGH;

    return sequence;
}

void digital_sequence_free(DigitalSequence* sequence) {
    furi_assert(sequence);

    free(sequence->data);
    free(sequence);
}

void digital_sequence_register_signal(
    DigitalSequence* sequence,
    uint8_t signal_index,
    const DigitalSignal* signal) {
    furi_assert(sequence);
    furi_assert(signal);
    furi_assert(signal_index < DIGITAL_SEQUENCE_BANK_SIZE);

    sequence->signals[signal_index] = signal;
}

void digital_sequence_add_signal(DigitalSequence* sequence, uint8_t signal_index) {
    furi_assert(sequence);
    furi_assert(signal_index < DIGITAL_SEQUENCE_BANK_SIZE);
    furi_assert(sequence->size < sequence->max_size);

    sequence->data[sequence->size++] = signal_index;
}

static inline void digital_sequence_start_dma(DigitalSequence* sequence) {
    furi_assert(sequence);

    LL_DMA_Init(DMA1, LL_DMA_CHANNEL_1, &sequence->dma_config_gpio);
    LL_DMA_Init(DMA1, LL_DMA_CHANNEL_2, &sequence->dma_config_timer);

    LL_DMA_EnableChannel(DMA1, LL_DMA_CHANNEL_1);
    LL_DMA_EnableChannel(DMA1, LL_DMA_CHANNEL_2);
}

static inline void digital_sequence_stop_dma() {
    LL_DMA_DisableChannel(DMA1, LL_DMA_CHANNEL_1);
    LL_DMA_DisableChannel(DMA1, LL_DMA_CHANNEL_2);
    LL_DMA_ClearFlag_TC1(DMA1);
    LL_DMA_ClearFlag_TC2(DMA1);
}

static inline void digital_sequence_start_timer() {
    furi_hal_bus_enable(FuriHalBusTIM2);

    LL_TIM_SetCounterMode(TIM2, LL_TIM_COUNTERMODE_UP);
    LL_TIM_SetClockDivision(TIM2, LL_TIM_CLOCKDIVISION_DIV1);
    LL_TIM_SetPrescaler(TIM2, 0);
    LL_TIM_SetAutoReload(TIM2, DIGITAL_SEQUENCE_TIMER_MAX);
    LL_TIM_SetCounter(TIM2, 0);

    LL_TIM_EnableCounter(TIM2);
    LL_TIM_EnableUpdateEvent(TIM2);
    LL_TIM_EnableDMAReq_UPDATE(TIM2);
    LL_TIM_GenerateEvent_UPDATE(TIM2);
}

static void digital_sequence_stop_timer() {
    LL_TIM_DisableCounter(TIM2);
    LL_TIM_DisableUpdateEvent(TIM2);
    LL_TIM_DisableDMAReq_UPDATE(TIM2);

    furi_hal_bus_disable(FuriHalBusTIM2);
}

static inline void digital_sequence_init_gpio_buffer(
    DigitalSequence* sequence,
    const DigitalSignal* first_signal) {
    const uint32_t bit_set = sequence->gpio->pin << GPIO_BSRR_BS0_Pos
#ifdef DIGITAL_SIGNAL_DEBUG_OUTPUT_PIN
                             | DIGITAL_SIGNAL_DEBUG_OUTPUT_PIN.pin << GPIO_BSRR_BS0_Pos
#endif
        ;

    const uint32_t bit_reset = sequence->gpio->pin << GPIO_BSRR_BR0_Pos
#ifdef DIGITAL_SIGNAL_DEBUG_OUTPUT_PIN
                               | DIGITAL_SIGNAL_DEBUG_OUTPUT_PIN.pin << GPIO_BSRR_BR0_Pos
#endif
        ;

    if(first_signal->start_level) {
        sequence->gpio_buf[0] = bit_set;
        sequence->gpio_buf[1] = bit_reset;
    } else {
        sequence->gpio_buf[0] = bit_reset;
        sequence->gpio_buf[1] = bit_set;
    }
}

static inline void digital_sequence_finish(DigitalSequence* sequence) {
    if(sequence->state == DigitalSequenceStateActive) {
        const uint32_t prev_timer = DWT->CYCCNT;

        do {
            /* Special value has been loaded into the timer, signaling the end of transmission. */
            if(TIM2->ARR == DIGITAL_SEQUENCE_TIMER_MAX) {
                break;
            }

            if(DWT->CYCCNT - prev_timer > DIGITAL_SEQUENCE_LOCK_WAIT_TICKS) {
                DigitalSequenceRingBuffer* dma_buffer = &sequence->timer_buf;
                dma_buffer->read_pos = DIGITAL_SEQUENCE_RING_BUFFER_SIZE -
                                       LL_DMA_GetDataLength(DMA1, LL_DMA_CHANNEL_2);
                FURI_LOG_D(
                    TAG,
                    "[SEQ] hung %lu ms in finish (ARR 0x%08lx, read %lu, write %lu)",
                    DIGITAL_SEQUENCE_LOCK_WAIT_MS,
                    TIM2->ARR,
                    dma_buffer->read_pos,
                    dma_buffer->write_pos);
                break;
            }
        } while(true);
    }

    digital_sequence_stop_timer();
    digital_sequence_stop_dma();
}

static inline void digital_sequence_enqueue_period(DigitalSequence* sequence, uint32_t length) {
    DigitalSequenceRingBuffer* dma_buffer = &sequence->timer_buf;

    if(sequence->state == DigitalSequenceStateActive) {
        const uint32_t prev_timer = DWT->CYCCNT;

        do {
            dma_buffer->read_pos =
                DIGITAL_SEQUENCE_RING_BUFFER_SIZE - LL_DMA_GetDataLength(DMA1, LL_DMA_CHANNEL_2);

            const uint32_t size_free = (DIGITAL_SEQUENCE_RING_BUFFER_SIZE + dma_buffer->read_pos -
                                        dma_buffer->write_pos) %
                                       DIGITAL_SEQUENCE_RING_BUFFER_SIZE;

            if(size_free > DIGITAL_SEQUENCE_RING_BUFFER_MIN_FREE_SIZE) {
                break;
            }

            if(DWT->CYCCNT - prev_timer > DIGITAL_SEQUENCE_LOCK_WAIT_TICKS) {
                FURI_LOG_D(
                    TAG,
                    "[SEQ] hung %lu ms in queue (ARR 0x%08lx, read %lu, write %lu)",
                    DIGITAL_SEQUENCE_LOCK_WAIT_MS,
                    TIM2->ARR,
                    dma_buffer->read_pos,
                    dma_buffer->write_pos);
                break;
            }

            if(TIM2->ARR == DIGITAL_SEQUENCE_TIMER_MAX) {
                FURI_LOG_D(
                    TAG,
                    "[SEQ] buffer underrun in queue (ARR 0x%08lx, read %lu, write %lu)",
                    TIM2->ARR,
                    dma_buffer->read_pos,
                    dma_buffer->write_pos);
                break;
            }
        } while(true);
    }

    dma_buffer->data[dma_buffer->write_pos] = length;

    dma_buffer->write_pos += 1;
    dma_buffer->write_pos %= DIGITAL_SEQUENCE_RING_BUFFER_SIZE;

    dma_buffer->data[dma_buffer->write_pos] = DIGITAL_SEQUENCE_TIMER_MAX;
}

static inline void digital_sequence_timer_buffer_reset(DigitalSequence* sequence) {
    sequence->timer_buf.data[0] = DIGITAL_SEQUENCE_TIMER_MAX;
    sequence->timer_buf.read_pos = 0;
    sequence->timer_buf.write_pos = 0;
}

void digital_sequence_transmit(DigitalSequence* sequence) {
    furi_assert(sequence);
    furi_assert(sequence->size);
    furi_assert(sequence->state == DigitalSequenceStateIdle);

    FURI_CRITICAL_ENTER();

    furi_hal_gpio_init(sequence->gpio, GpioModeOutputPushPull, GpioPullNo, GpioSpeedVeryHigh);
#ifdef DIGITAL_SIGNAL_DEBUG_OUTPUT_PIN
    furi_hal_gpio_init(
        &DIGITAL_SIGNAL_DEBUG_OUTPUT_PIN, GpioModeOutputPushPull, GpioPullNo, GpioSpeedVeryHigh);
#endif

    const DigitalSignal* signal_current = sequence->signals[sequence->data[0]];

    digital_sequence_init_gpio_buffer(sequence, signal_current);

    int32_t remainder_ticks = 0;
    uint32_t reload_value_carry = 0;
    uint32_t next_signal_index = 1;

    for(;;) {
        const DigitalSignal* signal_next =
            (next_signal_index < sequence->size) ?
                sequence->signals[sequence->data[next_signal_index++]] :
                NULL;

        for(uint32_t i = 0; i < signal_current->size; i++) {
            const bool is_last_value = (i == signal_current->size - 1);
            const uint32_t reload_value = signal_current->data[i] + reload_value_carry;

            reload_value_carry = 0;

            if(is_last_value) {
                if(signal_next != NULL) {
                    /* Special case: signal boundary. Depending on whether the adjacent levels are equal or not,
                     * they will be combined to a single one or handled separately. */
                    const bool end_level = signal_current->start_level ^
                                           ((signal_current->size % 2) == 0);

                    /* If the adjacent levels are equal, carry the current period duration over to the next signal. */
                    if(end_level == signal_next->start_level) {
                        reload_value_carry = reload_value;
                    }
                } else {
                    /** Special case: during the last period of the last signal, hold the output level indefinitely.
                     * @see digital_signal.h
                     *
                     * Setting reload_value_carry to a non-zero value will prevent the respective period from being
                     * added to the DMA ring buffer. */
                    reload_value_carry = 1;
                }
            }

            /* A non-zero reload_value_carry means that the level was the same on the both sides of the signal boundary
             * and the two respective periods were combined to one. */
            if(reload_value_carry == 0) {
                digital_sequence_enqueue_period(sequence, reload_value);
            }

            if(sequence->state == DigitalSequenceStateIdle) {
                const bool is_buffer_filled = sequence->timer_buf.write_pos >=
                                              (DIGITAL_SEQUENCE_RING_BUFFER_SIZE -
                                               DIGITAL_SEQUENCE_RING_BUFFER_MIN_FREE_SIZE);
                const bool is_end_of_data = (signal_next == NULL) && is_last_value;

                if(is_buffer_filled || is_end_of_data) {
                    digital_sequence_start_dma(sequence);
                    digital_sequence_start_timer();
                    sequence->state = DigitalSequenceStateActive;
                }
            }
        }

        /* Exit the loop here when no further signals are available */
        if(signal_next == NULL) break;

        /* Prevent the rounding error from accumulating by distributing it across multiple periods. */
        remainder_ticks += signal_current->remainder;
        if(remainder_ticks >= DIGITAL_SIGNAL_T_TIM_DIV2) {
            remainder_ticks -= DIGITAL_SIGNAL_T_TIM;
            reload_value_carry += 1;
        }

        signal_current = signal_next;
    };

    digital_sequence_finish(sequence);
    digital_sequence_timer_buffer_reset(sequence);

    FURI_CRITICAL_EXIT();

    sequence->state = DigitalSequenceStateIdle;
}

void digital_sequence_clear(DigitalSequence* sequence) {
    furi_assert(sequence);

    sequence->size = 0;
}