#include "i2c_driver.h"
#include "gd32f4xx.h"
#include <cstddef>

#define I2C_TIMEOUT 50000

struct i2c_hw_config_t
{
    uint32_t i2c_periph;
    rcu_periph_enum rcu_clock;
    uint32_t gpio_port;
    uint32_t scl_pin;
    uint32_t sda_pin;
    uint32_t af;
    rcu_periph_enum gpio_rcu;
};

static constexpr i2c_hw_config_t i2c_hw_map[] = {
    {I2C0, RCU_I2C0, GPIOB, GPIO_PIN_6, GPIO_PIN_7, GPIO_AF_4, RCU_GPIOB},
    {I2C1, RCU_I2C1, GPIOB, GPIO_PIN_10, GPIO_PIN_11, GPIO_AF_4, RCU_GPIOB},
    {I2C2, RCU_I2C2, GPIOC, GPIO_PIN_4, GPIO_PIN_5, GPIO_AF_4, RCU_GPIOC},
};

static RetCode wait_flag(uint32_t i2c_periph, i2c_flag_enum flag)
{
    uint32_t timeout = I2C_TIMEOUT;
    while (RESET == i2c_flag_get(i2c_periph, flag))
    {
        if (--timeout == 0)
        {
            return RET_ERROR;
        }
    }
    return RET_OK;
}

extern "C"
{

    static I2cBus i2c_0(I2cPort::_0);
    static I2cBus i2c_1(I2cPort::_1);
    static I2cBus i2c_2(I2cPort::_2);
    static I2cBus *i2c_instances[] = {&i2c_0, &i2c_1, &i2c_2};
    static uint8_t i2c_inited[3] = {0};

    int i2c_init(uint8_t port, uint32_t speed_hz)
    {
        if (port >= 3)
            return -1;
        I2cConfig cfg;
        cfg.speed_hz = speed_hz;
        RetCode ret = i2c_instances[port]->init(cfg);
        i2c_inited[port] = (ret == RET_OK) ? 1 : 0;
        return i2c_inited[port] ? 0 : -1;
    }

    int i2c_master_write(uint8_t port, uint16_t dev_addr, const uint8_t *data, uint32_t len)
    {
        if (port >= 3 || !i2c_inited[port])
            return -1;
        I2cDevice dev(dev_addr);
        return i2c_instances[port]->master_write(dev, data, len) == RET_OK ? 0 : -1;
    }

    int i2c_master_read(uint8_t port, uint16_t dev_addr, uint8_t *data, uint32_t len)
    {
        if (port >= 3 || !i2c_inited[port])
            return -1;
        I2cDevice dev(dev_addr);
        return i2c_instances[port]->master_read(dev, data, len) == RET_OK ? 0 : -1;
    }

    int i2c_master_write_read(uint8_t port, uint16_t dev_addr, const uint8_t *wdata, uint32_t wlen, uint8_t *rdata, uint32_t rlen)
    {
        if (port >= 3 || !i2c_inited[port])
            return -1;
        I2cDevice dev(dev_addr);
        return i2c_instances[port]->master_write_read(dev, wdata, wlen, rdata, rlen) == RET_OK ? 0 : -1;
    }

} /* extern "C" */

I2cDevice::I2cDevice(uint16_t dev_addr)
    : dev_addr_(dev_addr)
{
}

RetCode I2cDevice::init()
{
    return RET_OK;
}

I2cBus::I2cBus(I2cPort port)
    : port_(port)
{
}

I2cBus::~I2cBus()
{
    if (initialized_)
    {
        deinit();
    }
}

RetCode I2cBus::init(const I2cConfig &config)
{
    uint8_t port_idx = static_cast<uint8_t>(port_);
    if (port_idx >= sizeof(i2c_hw_map) / sizeof(i2c_hw_map[0]))
    {
        return RET_INVALID_PARAM;
    }

    const i2c_hw_config_t &hw = i2c_hw_map[port_idx];
    if (hw.i2c_periph == 0)
    {
        return RET_NOT_SUPPORTED;
    }

    config_ = config;

    rcu_periph_clock_enable(hw.rcu_clock);
    rcu_periph_clock_enable(hw.gpio_rcu);

    gpio_af_set(hw.gpio_port, hw.af, hw.scl_pin | hw.sda_pin);
    gpio_mode_set(hw.gpio_port, GPIO_MODE_AF, GPIO_PUPD_PULLUP, hw.scl_pin | hw.sda_pin);
    gpio_output_options_set(hw.gpio_port, GPIO_OTYPE_OD, GPIO_OSPEED_50MHZ, hw.scl_pin | hw.sda_pin);

    i2c_deinit(hw.i2c_periph);

    uint32_t speed = config.speed_hz;
    if (speed == 0)
    {
        speed = 100000;
    }
    i2c_clock_config(hw.i2c_periph, speed, I2C_DTCY_2);
    i2c_mode_addr_config(hw.i2c_periph, I2C_I2CMODE_ENABLE, I2C_ADDFORMAT_7BITS, 0x00);
    i2c_enable(hw.i2c_periph);
    i2c_ack_config(hw.i2c_periph, I2C_ACK_ENABLE);

    initialized_ = true;
    return RET_OK;
}

RetCode I2cBus::deinit()
{
    uint8_t port_idx = static_cast<uint8_t>(port_);
    if (port_idx >= sizeof(i2c_hw_map) / sizeof(i2c_hw_map[0]))
    {
        return RET_INVALID_PARAM;
    }

    const i2c_hw_config_t &hw = i2c_hw_map[port_idx];

    i2c_deinit(hw.i2c_periph);
    rcu_periph_clock_disable(hw.rcu_clock);

    initialized_ = false;
    return RET_OK;
}

static RetCode i2c_master_start(uint32_t i2c_periph, uint16_t addr, uint32_t direction)
{
    uint32_t timeout = I2C_TIMEOUT;
    while (i2c_flag_get(i2c_periph, I2C_FLAG_I2CBSY))
    {
        if (--timeout == 0)
        {
            return RET_TIMEOUT;
        }
    }

    i2c_start_on_bus(i2c_periph);
    if (wait_flag(i2c_periph, I2C_FLAG_SBSEND) != RET_OK)
    {
        return RET_TIMEOUT;
    }

    i2c_master_addressing(i2c_periph, addr, direction);
    if (wait_flag(i2c_periph, I2C_FLAG_ADDSEND) != RET_OK)
    {
        return RET_TIMEOUT;
    }

    i2c_flag_clear(i2c_periph, I2C_FLAG_ADDSEND);

    return RET_OK;
}

RetCode I2cBus::master_write(I2cDevice &dev, const uint8_t *data, uint32_t len)
{
    if (data == nullptr || len == 0)
    {
        return RET_INVALID_PARAM;
    }
    if (!initialized_)
        return RET_NOT_INITIALIZED;

    uint8_t port_idx = static_cast<uint8_t>(port_);
    const i2c_hw_config_t &hw = i2c_hw_map[port_idx];
    uint32_t i2c = hw.i2c_periph;

    RetCode ret = i2c_master_start(i2c, dev.dev_addr_, I2C_TRANSMITTER);
    if (ret != RET_OK)
    {
        i2c_stop_on_bus(i2c);
        return ret;
    }

    for (uint32_t i = 0; i < len; i++)
    {
        if (wait_flag(i2c, I2C_FLAG_TBE) != RET_OK)
        {
            i2c_stop_on_bus(i2c);
            return RET_TIMEOUT;
        }
        i2c_data_transmit(i2c, data[i]);
    }

    if (wait_flag(i2c, I2C_FLAG_TBE) != RET_OK)
    {
        i2c_stop_on_bus(i2c);
        return RET_TIMEOUT;
    }

    i2c_stop_on_bus(i2c);
    return RET_OK;
}

RetCode I2cBus::master_read(I2cDevice &dev, uint8_t *data, uint32_t len)
{
    if (data == nullptr || len == 0)
    {
        return RET_INVALID_PARAM;
    }
    if (!initialized_)
        return RET_NOT_INITIALIZED;

    uint8_t port_idx = static_cast<uint8_t>(port_);
    const i2c_hw_config_t &hw = i2c_hw_map[port_idx];
    uint32_t i2c = hw.i2c_periph;

    if (len == 1)
    {
        i2c_ack_config(i2c, I2C_ACK_DISABLE);
    }
    else
    {
        i2c_ack_config(i2c, I2C_ACK_ENABLE);
    }

    RetCode ret = i2c_master_start(i2c, dev.dev_addr_, I2C_RECEIVER);
    if (ret != RET_OK)
    {
        i2c_stop_on_bus(i2c);
        return ret;
    }

    for (uint32_t i = 0; i < len; i++)
    {
        if (i == len - 1)
        {
            i2c_ack_config(i2c, I2C_ACK_DISABLE);
            i2c_stop_on_bus(i2c);
        }

        if (wait_flag(i2c, I2C_FLAG_RBNE) != RET_OK)
        {
            i2c_stop_on_bus(i2c);
            return RET_TIMEOUT;
        }
        data[i] = i2c_data_receive(i2c);
    }

    return RET_OK;
}

RetCode I2cBus::master_write_read(I2cDevice &dev, const uint8_t *wdata, uint32_t wlen, uint8_t *rdata, uint32_t rlen)
{
    if (wdata == nullptr || wlen == 0 || rdata == nullptr || rlen == 0)
    {
        return RET_INVALID_PARAM;
    }
    if (!initialized_)
        return RET_NOT_INITIALIZED;

    uint8_t port_idx = static_cast<uint8_t>(port_);
    const i2c_hw_config_t &hw = i2c_hw_map[port_idx];
    uint32_t i2c = hw.i2c_periph;

    // === 写阶段：发送寄存器地址（不发 STOP） ===

    uint32_t timeout = I2C_TIMEOUT;
    while (i2c_flag_get(i2c, I2C_FLAG_I2CBSY))
    {
        if (--timeout == 0)
            return RET_TIMEOUT;
    }

    i2c_start_on_bus(i2c);
    if (wait_flag(i2c, I2C_FLAG_SBSEND) != RET_OK)
    {
        i2c_stop_on_bus(i2c);
        return RET_TIMEOUT;
    }

    i2c_master_addressing(i2c, dev.dev_addr_, I2C_TRANSMITTER);
    if (wait_flag(i2c, I2C_FLAG_ADDSEND) != RET_OK)
    {
        i2c_stop_on_bus(i2c);
        return RET_TIMEOUT;
    }
    i2c_flag_clear(i2c, I2C_FLAG_ADDSEND);

    for (uint32_t i = 0; i < wlen; i++)
    {
        if (wait_flag(i2c, I2C_FLAG_TBE) != RET_OK)
        {
            i2c_stop_on_bus(i2c);
            return RET_TIMEOUT;
        }
        i2c_data_transmit(i2c, wdata[i]);
    }
    if (wait_flag(i2c, I2C_FLAG_TBE) != RET_OK)
    {
        i2c_stop_on_bus(i2c);
        return RET_TIMEOUT;
    }

    // === 读阶段：以重复起始条件开始（无 STOP 间隔） ===

    if (rlen == 1)
    {
        i2c_ack_config(i2c, I2C_ACK_DISABLE);
    }
    else
    {
        i2c_ack_config(i2c, I2C_ACK_ENABLE);
    }

    i2c_start_on_bus(i2c);
    if (wait_flag(i2c, I2C_FLAG_SBSEND) != RET_OK)
    {
        i2c_stop_on_bus(i2c);
        return RET_TIMEOUT;
    }

    i2c_master_addressing(i2c, dev.dev_addr_, I2C_RECEIVER);
    if (wait_flag(i2c, I2C_FLAG_ADDSEND) != RET_OK)
    {
        i2c_stop_on_bus(i2c);
        return RET_TIMEOUT;
    }
    i2c_flag_clear(i2c, I2C_FLAG_ADDSEND);

    for (uint32_t i = 0; i < rlen; i++)
    {
        if (i == rlen - 1)
        {
            i2c_ack_config(i2c, I2C_ACK_DISABLE);
            i2c_stop_on_bus(i2c);
        }
        if (wait_flag(i2c, I2C_FLAG_RBNE) != RET_OK)
        {
            i2c_stop_on_bus(i2c);
            return RET_TIMEOUT;
        }
        rdata[i] = i2c_data_receive(i2c);
    }

    return RET_OK;
}