#include "uart_driver.h"
#include "gd32f4xx.h"
#include <cstddef>
#include <cstdio>
#include <cerrno>
#include <sys/stat.h>
#include <sys/unistd.h>

struct uart_hw_config_t {
    uint32_t uart_base;
    rcu_periph_enum rcu_clock;
    uint32_t gpio_port;
    rcu_periph_enum gpio_rcu;
    uint32_t tx_pin;
    uint32_t rx_pin;
    uint32_t af;
};

static constexpr uart_hw_config_t uart_hw_map[] = {
    {USART0, RCU_USART0, GPIOA, RCU_GPIOA, GPIO_PIN_9,  GPIO_PIN_10, GPIO_AF_7},
    {USART1, RCU_USART1, GPIOA, RCU_GPIOA, GPIO_PIN_2,  GPIO_PIN_3,  GPIO_AF_7},
    {USART2, RCU_USART2, GPIOB, RCU_GPIOB, GPIO_PIN_10, GPIO_PIN_11, GPIO_AF_7},
    {UART3,  RCU_UART3,  GPIOC, RCU_GPIOC, GPIO_PIN_10, GPIO_PIN_11, GPIO_AF_7},
    {UART4,  RCU_UART4,  GPIOC, RCU_GPIOC, GPIO_PIN_12, GPIO_PIN_2,  GPIO_AF_7},
    {USART5, RCU_USART5, GPIOD, RCU_GPIOD, GPIO_PIN_2,  GPIO_PIN_3,  GPIO_AF_7},
    {UART6,  RCU_UART6,  GPIOG, RCU_GPIOG, GPIO_PIN_6,  GPIO_PIN_7,  GPIO_AF_7},
};

USART *USART::default_ = nullptr;

USART::USART(UartPort port, uint32_t baudrate)
    : port_(port), baudrate_(baudrate)
{
    uint8_t port_idx = static_cast<uint8_t>(port_);
    if (port_idx >= sizeof(uart_hw_map) / sizeof(uart_hw_map[0])) {
        return;
    }

    const uart_hw_config_t &hw = uart_hw_map[port_idx];
    if (hw.uart_base == 0) {
        return;
    }

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

    gpio_af_set(hw.gpio_port, hw.af, hw.tx_pin | hw.rx_pin);
    gpio_mode_set(hw.gpio_port, GPIO_MODE_AF, GPIO_PUPD_PULLUP, hw.tx_pin | hw.rx_pin);
    gpio_output_options_set(hw.gpio_port, GPIO_OTYPE_PP, GPIO_OSPEED_50MHZ, hw.tx_pin | hw.rx_pin);

    usart_deinit(hw.uart_base);
    usart_baudrate_set(hw.uart_base, baudrate_);
    usart_receive_config(hw.uart_base, USART_RECEIVE_ENABLE);
    usart_transmit_config(hw.uart_base, USART_TRANSMIT_ENABLE);
    usart_enable(hw.uart_base);

    initialized_ = true;
}

USART::~USART()
{
    if (initialized_) {
        uint8_t port_idx = static_cast<uint8_t>(port_);
        if (port_idx < sizeof(uart_hw_map) / sizeof(uart_hw_map[0])) {
            usart_disable(uart_hw_map[port_idx].uart_base);
        }
        initialized_ = false;
    }
    if (default_ == this) {
        default_ = nullptr;
    }
}

RetCode USART::send_byte(uint8_t data)
{
    if (!initialized_) return RET_NOT_INITIALIZED;

    uint8_t port_idx = static_cast<uint8_t>(port_);
    const uart_hw_config_t &hw = uart_hw_map[port_idx];

    while (RESET == usart_flag_get(hw.uart_base, USART_FLAG_TBE));
    usart_data_transmit(hw.uart_base, data);
    while (RESET == usart_flag_get(hw.uart_base, USART_FLAG_TC));

    return RET_OK;
}

RetCode USART::send_data(const uint8_t *data, uint32_t len)
{
    if (!initialized_) return RET_NOT_INITIALIZED;
    if (data == nullptr || len == 0) return RET_INVALID_PARAM;

    uint8_t port_idx = static_cast<uint8_t>(port_);
    const uart_hw_config_t &hw = uart_hw_map[port_idx];

    for (uint32_t i = 0; i < len; i++) {
        while (RESET == usart_flag_get(hw.uart_base, USART_FLAG_TBE));
        usart_data_transmit(hw.uart_base, data[i]);
    }
    while (RESET == usart_flag_get(hw.uart_base, USART_FLAG_TC));

    return RET_OK;
}

RetCode USART::receive_byte(uint8_t *data, uint32_t timeout_ms)
{
    if (!initialized_) return RET_NOT_INITIALIZED;
    if (data == nullptr) return RET_INVALID_PARAM;

    uint8_t port_idx = static_cast<uint8_t>(port_);
    const uart_hw_config_t &hw = uart_hw_map[port_idx];

    if (timeout_ms == 0) {
        while (RESET == usart_flag_get(hw.uart_base, USART_FLAG_RBNE));
        *data = static_cast<uint8_t>(usart_data_receive(hw.uart_base));
        return RET_OK;
    }

    uint32_t timeout = timeout_ms * 10000;
    while (RESET == usart_flag_get(hw.uart_base, USART_FLAG_RBNE)) {
        if (--timeout == 0) {
            return RET_TIMEOUT;
        }
    }
    *data = static_cast<uint8_t>(usart_data_receive(hw.uart_base));

    return RET_OK;
}

void USART::reinit(uint32_t baudrate)
{
    if (!initialized_) return;

    uint8_t port_idx = static_cast<uint8_t>(port_);
    if (port_idx >= sizeof(uart_hw_map) / sizeof(uart_hw_map[0])) return;

    const uart_hw_config_t &hw = uart_hw_map[port_idx];
    baudrate_ = baudrate;

    usart_disable(hw.uart_base);
    usart_baudrate_set(hw.uart_base, baudrate_);
    usart_enable(hw.uart_base);
}

void USART::setDefault(USART *uart)
{
    default_ = uart;
}

extern "C" int _write(int file, char *ptr, int len)
{
    if (file == STDOUT_FILENO || file == STDERR_FILENO) {
        USART *uart = USART::defaultInstance();
        if (uart) {
            uart->send_data(reinterpret_cast<const uint8_t *>(ptr), static_cast<uint32_t>(len));
        }
        return len;
    }
    errno = EBADF;
    return -1;
}

extern "C" int _read(int file, char *ptr, int len)
{
    (void)file;
    (void)ptr;
    (void)len;
    errno = ENOSYS;
    return -1;
}

extern "C" int _close(int file)
{
    (void)file;
    return -1;
}

extern "C" off_t _lseek(int file, off_t ptr, int dir)
{
    (void)file;
    (void)ptr;
    (void)dir;
    return 0;
}

extern "C" int _fstat(int file, struct stat *st)
{
    (void)file;
    st->st_mode = S_IFCHR;
    return 0;
}

extern "C" int _isatty(int file)
{
    if (file == STDOUT_FILENO || file == STDERR_FILENO || file == STDIN_FILENO) {
        return 1;
    }
    return 0;
}

extern "C" int _getpid(void)
{
    return 1;
}

extern "C" int _kill(int pid, int sig)
{
    (void)pid;
    (void)sig;
    errno = EINVAL;
    return -1;
}

extern "C" void _exit(int status)
{
    (void)status;
    while (1);
}

/* USART global instances */
USART uart_0(UartPort::_0);
USART uart_1(UartPort::_1);
static USART uart_2(UartPort::_2);
static USART uart_3(UartPort::_3);
static USART uart_4(UartPort::_4);
static USART uart_5(UartPort::_5);
static USART uart_6(UartPort::_6);
static USART *uart_instances[] = {
    &uart_0, &uart_1, &uart_2, &uart_3, &uart_4, &uart_5, &uart_6,
};
static uint8_t uart_inited[7] = {0};

/* C-compatible wrappers for legacy code */
extern "C" {

int uart_init(uint8_t port, uint32_t baudrate)
{
    if (port >= 7) return -1;
    uart_inited[port] = 1;
    return 0;
}

int uart_send_byte(uint8_t port, uint8_t data)
{
    if (port >= 7 || !uart_inited[port]) return -1;
    return uart_instances[port]->send_byte(data) == RET_OK ? 0 : -1;
}

int uart_send_data(uint8_t port, const uint8_t *data, uint32_t len)
{
    if (port >= 7 || !uart_inited[port]) return -1;
    return uart_instances[port]->send_data(data, len) == RET_OK ? 0 : -1;
}

int uart_receive_byte(uint8_t port, uint8_t *data, uint32_t timeout_ms)
{
    if (port >= 7 || !uart_inited[port]) return -1;
    return uart_instances[port]->receive_byte(data, timeout_ms) == RET_OK ? 0 : -1;
}

} /* extern "C" */