/*
 * Copyright (c) 2022 The ZMK Contributors
 *
 * SPDX-License-Identifier: MIT
 */

#include "debounce.h"

#include <device.h>
#include <devicetree.h>
#include <drivers/gpio.h>
#include <drivers/kscan.h>
#include <kernel.h>
#include <logging/log.h>
#include <sys/__assert.h>
#include <sys/util.h>

LOG_MODULE_DECLARE(zmk, CONFIG_ZMK_LOG_LEVEL);

#define DT_DRV_COMPAT zmk_kscan_gpio_round_robin_matrix

#define INST_INPUTS_LEN(n) DT_INST_PROP_LEN(n, input_gpios)
#define INST_OUTPUTS_LEN(n) DT_INST_PROP_LEN(n, output_gpios)
#define INST_MATRIX_LEN(n) (INST_INPUTS_LEN(n) * INST_OUTPUTS_LEN(n))

#if CONFIG_ZMK_KSCAN_DEBOUNCE_PRESS_MS >= 0
#define INST_DEBOUNCE_PRESS_MS(n) CONFIG_ZMK_KSCAN_DEBOUNCE_PRESS_MS
#else
#define INST_DEBOUNCE_PRESS_MS(n)                                                                  \
    DT_INST_PROP(n, debounce_press_ms)
#endif

#if CONFIG_ZMK_KSCAN_DEBOUNCE_RELEASE_MS >= 0
#define INST_DEBOUNCE_RELEASE_MS(n) CONFIG_ZMK_KSCAN_DEBOUNCE_RELEASE_MS
#else
#define INST_DEBOUNCE_RELEASE_MS(n)                                                                \
    DT_INST_PROP(n, debounce_release_ms)
#endif

#define KSCAN_GPIO_INPUT_CFG_INIT(idx, inst_idx)                                                   \
    GPIO_DT_SPEC_GET_BY_IDX(DT_DRV_INST(inst_idx), input_gpios, idx),
#define KSCAN_GPIO_OUTPUT_CFG_INIT(idx, inst_idx)                                                  \
    GPIO_DT_SPEC_GET_BY_IDX(DT_DRV_INST(inst_idx), output_gpios, idx),

struct kscan_round_robin_matrix_data {
    const struct device *dev;
    kscan_callback_t callback;
    struct k_work_delayable work;
    int64_t scan_time;
    struct debounce_state *matrix_state;
};

struct kscan_round_robin_matrix_config {
    const struct gpio_dt_spec *inputs;
    const struct gpio_dt_spec *outputs;
    size_t gpios_len;
    struct debounce_config debounce_config;
    int32_t poll_period_ms;
};

static int state_index_io(const struct kscan_round_robin_matrix_config *config, const int input_idx,
                          const int output_idx) {
    __ASSERT(input_idx < config->gpios_len, "Invalid input %i", input_idx);
    __ASSERT(output_idx < config->gpios_len, "Invalid output %i", output_idx);

    return ((input_idx * config->gpios_len) + output_idx);
}

static int kscan_round_robin_matrix_read(const struct device *dev) {
    struct kscan_round_robin_matrix_data *data = dev->data;
    const struct kscan_round_robin_matrix_config *config = dev->config;

    for (int o = 0; o < config->gpios_len; o++) {
        const struct gpio_dt_spec *out_gpio = &config->outputs[o];

        // Init output
        if (!device_is_ready(out_gpio->port)) {
            LOG_ERR("GPIO is not ready: %s", out_gpio->port->name);
            return -ENODEV;
        }

        int err = gpio_pin_configure_dt(out_gpio, GPIO_OUTPUT);
        if (err) {
            LOG_ERR("Unable to configure pin %u on %s for output", out_gpio->pin,
                    out_gpio->port->name);
            return err;
        }

        LOG_DBG("Configured pin %u on %s for output", out_gpio->pin, out_gpio->port->name);

        // Init input
        for (int i = (o + 1) % config->gpios_len; i != o; i = (i + 1) % config->gpios_len) {
            const struct gpio_dt_spec *in_gpio = &config->inputs[i];

            if (!device_is_ready(in_gpio->port)) {
                LOG_ERR("GPIO is not ready: %s", in_gpio->port->name);
                return -ENODEV;
            }

            err = gpio_pin_configure_dt(in_gpio, GPIO_INPUT);
            if (err) {
                LOG_ERR("Unable to configure pin %u on %s for input", in_gpio->pin, in_gpio->port->name);
                return err;
            }

            LOG_DBG("Configured pin %u on %s for input", in_gpio->pin, in_gpio->port->name);
        }

        err = gpio_pin_set_dt(out_gpio, 1);
        if (err) {
            LOG_ERR("Failed to set output %i active: %i", o, err);
            return err;
        }

        for (int i = (o + 1) % config->gpios_len; i != o; i = (i + 1) % config->gpios_len) {
            const struct gpio_dt_spec *in_gpio = &config->inputs[i];

            const int index = state_index_io(config, i, o);
            const bool is_active = gpio_pin_get_dt(in_gpio);
            struct debounce_state *state = &data->matrix_state[index];

            debounce_update(state, is_active, config->poll_period_ms,
                            &config->debounce_config);

            if (debounce_get_changed(state)) {
                const bool is_pressed = debounce_is_pressed(state);

                LOG_DBG("Sending event at %i,%i state %s", o, i, is_pressed ? "on" : "off");
                data->callback(dev, o, i, is_pressed);
            }
        }

        err = gpio_pin_set_dt(out_gpio, 0);
        if (err) {
            LOG_ERR("Failed to set output %i inactive: %i", o, err);
            return err;
        }

#if CONFIG_ZMK_KSCAN_ROUND_ROBIN_MATRIX_WAIT_BETWEEN_OUTPUTS > 0
        k_busy_wait(CONFIG_ZMK_KSCAN_ROUND_ROBIN_MATRIX_WAIT_BETWEEN_OUTPUTS);
#endif
    }

    data->scan_time += config->poll_period_ms;

    k_work_reschedule(&data->work, K_TIMEOUT_ABS_MS(data->scan_time));

    return 0;
}

static void kscan_matrix_work_handler(struct k_work *work) {
    struct k_work_delayable *dwork = CONTAINER_OF(work, struct k_work_delayable, work);
    struct kscan_round_robin_matrix_data *data = CONTAINER_OF(dwork,
                                                              struct kscan_round_robin_matrix_data,
                                                              work);
    kscan_round_robin_matrix_read(data->dev);
}

static int kscan_matrix_configure(const struct device *dev, const kscan_callback_t callback) {
    struct kscan_round_robin_matrix_data *data = dev->data;

    if (!callback) {
        return -EINVAL;
    }

    data->callback = callback;
    return 0;
}

static int kscan_matrix_enable(const struct device *dev) {
    struct kscan_round_robin_matrix_data *data = dev->data;

    data->scan_time = k_uptime_get();

    // Read will automatically start interrupts/polling once done.
    return kscan_round_robin_matrix_read(dev);
}

static int kscan_matrix_disable(const struct device *dev) {
    struct kscan_round_robin_matrix_data *data = dev->data;

    k_work_cancel_delayable(&data->work);

    return 0;
}

static int kscan_round_robin_matrix_init(const struct device *dev) {
    struct kscan_round_robin_matrix_data *data = dev->data;

    data->dev = dev;

    k_work_init_delayable(&data->work, kscan_matrix_work_handler);

    return 0;
}

static const struct kscan_driver_api kscan_round_robin_matrix_api = {
    .config = kscan_matrix_configure,
    .enable_callback = kscan_matrix_enable,
    .disable_callback = kscan_matrix_disable,
};

#define KSCAN_ROUND_ROBIN_MATRIX_INIT(n)                                                           \
    BUILD_ASSERT(INST_INPUTS_LEN(n) == INST_OUTPUTS_LEN(n),                                        \
                 "the number of input-gpios must be equal to output-gpios");                       \
    BUILD_ASSERT(INST_DEBOUNCE_PRESS_MS(n) <= DEBOUNCE_COUNTER_MAX,                                \
                 "ZMK_KSCAN_DEBOUNCE_PRESS_MS or debounce-press-ms is too large");                 \
    BUILD_ASSERT(INST_DEBOUNCE_RELEASE_MS(n) <= DEBOUNCE_COUNTER_MAX,                              \
                 "ZMK_KSCAN_DEBOUNCE_RELEASE_MS or debounce-release-ms is too large");             \
                                                                                                   \
    static const struct gpio_dt_spec kscan_round_robin_matrix_inputs_##n[] = {                     \
        UTIL_LISTIFY(INST_INPUTS_LEN(n), KSCAN_GPIO_INPUT_CFG_INIT, n)};                           \
                                                                                                   \
    static const struct gpio_dt_spec kscan_round_robin_matrix_outputs_##n[] = {                    \
        UTIL_LISTIFY(INST_OUTPUTS_LEN(n), KSCAN_GPIO_OUTPUT_CFG_INIT, n)};                         \
                                                                                                   \
    static struct debounce_state kscan_round_robin_matrix_state_##n[INST_MATRIX_LEN(n)];           \
                                                                                                   \
    static struct kscan_round_robin_matrix_data kscan_round_robin_matrix_data_##n = {              \
        .matrix_state = kscan_round_robin_matrix_state_##n, };                                     \
                                                                                                   \
    static struct kscan_round_robin_matrix_config kscan_round_robin_matrix_config_##n = {          \
        .inputs = kscan_round_robin_matrix_inputs_##n,                                             \
        .outputs = kscan_round_robin_matrix_outputs_##n,                                           \
        .gpios_len = INST_INPUTS_LEN(n),                                                           \
        .debounce_config =                                                                         \
            {                                                                                      \
                .debounce_press_ms = INST_DEBOUNCE_PRESS_MS(n),                                    \
                .debounce_release_ms = INST_DEBOUNCE_RELEASE_MS(n),                                \
            },                                                                                     \
        .poll_period_ms = DT_INST_PROP(n, poll_period_ms),                                         \
    };                                                                                             \
    DEVICE_DT_INST_DEFINE(n, &kscan_round_robin_matrix_init, NULL,                                 \
                          &kscan_round_robin_matrix_data_##n,                                      \
                          &kscan_round_robin_matrix_config_##n,                                    \
                          APPLICATION, CONFIG_APPLICATION_INIT_PRIORITY,                           \
                          &kscan_round_robin_matrix_api);

DT_INST_FOREACH_STATUS_OKAY(KSCAN_ROUND_ROBIN_MATRIX_INIT);