#include "adc_driver.h"
#include "gd32f4xx.h"
#include <cstddef>

struct adc_hw_config_t {
    uint32_t adc_periph;
    rcu_periph_enum rcu_clock;
};

static constexpr adc_hw_config_t adc_hw_map[] = {
    {ADC0, RCU_ADC0},
    {ADC1, RCU_ADC1},
    {ADC2, RCU_ADC2},
};

static bool adc_clock_configured = false;

static float adc_resolution_to_max_value(uint32_t resolution)
{
    if (resolution == ADC_RESOLUTION_12B) return 4095.0f;
    if (resolution == ADC_RESOLUTION_10B) return 1023.0f;
    if (resolution == ADC_RESOLUTION_8B)  return 255.0f;
    if (resolution == ADC_RESOLUTION_6B)  return 63.0f;
    return 4095.0f;
}

AdcBus::AdcBus(AdcPort port)
    : port_(port)
{
}

AdcBus::~AdcBus()
{
    if (initialized_) {
        deinit();
    }
}

RetCode AdcBus::init(const AdcConfig &config)
{
    uint8_t port_idx = static_cast<uint8_t>(port_);
    if (port_idx >= sizeof(adc_hw_map) / sizeof(adc_hw_map[0])) {
        return RET_INVALID_PARAM;
    }

    const adc_hw_config_t &hw = adc_hw_map[port_idx];
    if (hw.adc_periph == 0) {
        return RET_NOT_SUPPORTED;
    }

    config_ = config;

    rcu_periph_clock_enable(hw.rcu_clock);

    if (!adc_clock_configured) {
        adc_clock_config(config.clock_prescaler);
        adc_clock_configured = true;
    }

    adc_resolution_config(hw.adc_periph, config.resolution);
    adc_data_alignment_config(hw.adc_periph, ADC_DATAALIGN_RIGHT);

    if (config.use_dma) {
        adc_dma_mode_enable(hw.adc_periph);
    }

    adc_special_function_config(hw.adc_periph, ADC_SCAN_MODE, DISABLE);
    adc_special_function_config(hw.adc_periph, ADC_CONTINUOUS_MODE, DISABLE);

    adc_enable(hw.adc_periph);

    for (volatile uint32_t i = 0; i < 10000; i++);

    adc_calibration_enable(hw.adc_periph);

    if (config.use_interrupt) {
        adc_interrupt_enable(hw.adc_periph, ADC_INT_EOC);
        nvic_irq_enable(ADC_IRQn, 0, 0);
    }

    initialized_ = true;
    return RET_OK;
}

RetCode AdcBus::deinit()
{
    uint8_t port_idx = static_cast<uint8_t>(port_);
    if (port_idx >= sizeof(adc_hw_map) / sizeof(adc_hw_map[0])) {
        return RET_INVALID_PARAM;
    }

    const adc_hw_config_t &hw = adc_hw_map[port_idx];

    adc_disable(hw.adc_periph);
    rcu_periph_clock_disable(hw.rcu_clock);

    initialized_ = false;
    return RET_OK;
}

RetCode AdcBus::channel_config(uint8_t channel, uint8_t rank)
{
    uint8_t port_idx = static_cast<uint8_t>(port_);
    if (port_idx >= sizeof(adc_hw_map) / sizeof(adc_hw_map[0])) {
        return RET_INVALID_PARAM;
    }
    if (!initialized_) return RET_NOT_INITIALIZED;

    const adc_hw_config_t &hw = adc_hw_map[port_idx];

    adc_channel_length_config(hw.adc_periph, ADC_ROUTINE_CHANNEL, rank + 1);
    adc_routine_channel_config(hw.adc_periph, rank, channel, config_.sample_time);

    return RET_OK;
}

RetCode AdcBus::start_conversion(uint8_t channel)
{
    uint8_t port_idx = static_cast<uint8_t>(port_);
    if (port_idx >= sizeof(adc_hw_map) / sizeof(adc_hw_map[0])) {
        return RET_INVALID_PARAM;
    }
    if (!initialized_) return RET_NOT_INITIALIZED;

    const adc_hw_config_t &hw = adc_hw_map[port_idx];

    adc_routine_channel_config(hw.adc_periph, 0, channel, config_.sample_time);
    adc_software_trigger_enable(hw.adc_periph, ADC_ROUTINE_CHANNEL);

    return RET_OK;
}

uint16_t AdcBus::read()
{
    uint8_t port_idx = static_cast<uint8_t>(port_);
    if (port_idx >= sizeof(adc_hw_map) / sizeof(adc_hw_map[0])) {
        return 0;
    }
    if (!initialized_) return 0;

    const adc_hw_config_t &hw = adc_hw_map[port_idx];

    while (RESET == adc_flag_get(hw.adc_periph, ADC_FLAG_EOC));

    uint16_t value = static_cast<uint16_t>(adc_routine_data_read(hw.adc_periph));

    adc_flag_clear(hw.adc_periph, ADC_FLAG_EOC);

    return value;
}

float AdcBus::read_voltage()
{
    uint16_t raw = read();
    float max_val = adc_resolution_to_max_value(config_.resolution);
    return static_cast<float>(raw) * 3.3f / max_val;
}

void adc_irq_handler()
{
    if (adc_interrupt_flag_get(ADC0, ADC_INT_FLAG_EOC) != RESET) {
        adc_interrupt_flag_clear(ADC0, ADC_INT_FLAG_EOC);
    }
    if (adc_interrupt_flag_get(ADC1, ADC_INT_FLAG_EOC) != RESET) {
        adc_interrupt_flag_clear(ADC1, ADC_INT_FLAG_EOC);
    }
    if (adc_interrupt_flag_get(ADC2, ADC_INT_FLAG_EOC) != RESET) {
        adc_interrupt_flag_clear(ADC2, ADC_INT_FLAG_EOC);
    }
}

extern "C" {

static AdcBus adc_0(AdcPort::_0);
static AdcBus adc_1(AdcPort::_1);
static AdcBus adc_2(AdcPort::_2);
static AdcBus *adc_instances[] = { &adc_0, &adc_1, &adc_2 };
static uint8_t adc_inited[3] = {0};

int adc_init(uint8_t port, uint32_t resolution)
{
    if (port >= 3) return -1;
    AdcConfig cfg;
    cfg.resolution = resolution;
    cfg.clock_prescaler = ADC_ADCCK_PCLK2_DIV8;
    cfg.sample_time = ADC_SAMPLETIME_56;
    RetCode ret = adc_instances[port]->init(cfg);
    adc_inited[port] = (ret == RET_OK) ? 1 : 0;
    return adc_inited[port] ? 0 : -1;
}

uint16_t adc_read(uint8_t port, uint8_t channel)
{
    if (port >= 3 || !adc_inited[port]) return 0;
    adc_instances[port]->channel_config(channel, 0);
    adc_instances[port]->start_conversion(channel);
    return adc_instances[port]->read();
}

float adc_read_voltage(uint8_t port, uint8_t channel)
{
    if (port >= 3 || !adc_inited[port]) return 0.0f;
    adc_instances[port]->channel_config(channel, 0);
    adc_instances[port]->start_conversion(channel);
    return adc_instances[port]->read_voltage();
}

} /* extern "C" */