#define _GNU_SOURCE
#include <stdint.h>

/*
#include <libopencm3/stm32/usart.h>
#include <libopencm3/cm3/nvic.h>
#include <libopencm3/cm3/scb.h>
*/

#include <ctype.h>
#include <stdarg.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>
#include <stddef.h>
#include <limits.h>
#include <sys/types.h>

#include <console.h>
#include <macros.h>

#define CONFIG_USER_ECHO 1
#define RECV_BUF_LEN 128

struct usart_console {
	struct console console;
	char recv_buf[RECV_BUF_LEN];
	volatile size_t cur;
	volatile size_t next;
	unsigned irq_no;
	uint32_t dev;
};

static struct usart_console usart[2];

#if 0
#ifdef STM32F0
#define USART_STOPBITS_1 USART_CR2_STOP_1_0BIT
#endif

#ifdef STM32F1
#define USART_ISR_RXNE USART_SR_RXNE
#endif
#endif

void usart_send_blocking(uint32_t dev, char c) {
    return;
}

static void usart_isr(struct usart_console *console)
{
#if 0
	size_t i;

	if (!console)
		return;

	while (usart_get_flag(console->dev, USART_ISR_RXNE)) {
		console->recv_buf[console->next] = usart_recv(console->dev);

		i = (console->next + 1) % RECV_BUF_LEN;

		if (i != console->cur)
			console->next = i;
	}
#endif
}

void usart1_isr(void)
{
	usart_isr(usart + 0);
}

void usart2_isr(void)
{
	usart_isr(usart + 1);
}

int console_peek(char *c, struct console *console_, int block)
{
	struct usart_console *console = container_of(console_,
		struct usart_console, console);

	while (block && console->cur == console->next);

	if (console->cur != console->next) {
		*c = console->recv_buf[console->cur];
		return 0;
	}

	return -EAGAIN;
}

int console_getc(char *c, struct console *console_)
{
	struct usart_console *console = container_of(console_,
		struct usart_console, console);

	if (console->cur == console->next)
		return -1;

	if (console->cur != console->next) {
		*c = console->recv_buf[console->cur];
		console->cur = (console->cur + 1) % RECV_BUF_LEN;
	}

	return 0;
}

int console_getline(struct console *console_, char *buf, size_t n)
{
	struct usart_console *console = container_of(console_,
		struct usart_console, console);
	char *p = buf + strlen(buf);
	char c;

	*p = '\0';

	while (console_getc(&c, console_) == 0) {
		switch (c) {
		case '\r':
#if CONFIG_USER_ECHO
			usart_send_blocking(console->dev, '\r');
			usart_send_blocking(console->dev, '\n');
#endif
			return 0;
		case 10:
		case 127:
			if (buf < p) {
#if CONFIG_USER_ECHO
				usart_send_blocking(console->dev, '\010');
				usart_send_blocking(console->dev, ' ');
				usart_send_blocking(console->dev, '\010');
#endif

				--p;
			}

			break;
		default:
			*p = c;
#if CONFIG_USER_ECHO
			usart_send_blocking(console->dev, c);
#endif

			if (((size_t)p - (size_t)buf) < n) {
				++p;
			}
		}

		*p = '\0';
	}

	*p = '\0';

	return -EAGAIN;
}

ssize_t console_read(struct console *console, char *buf, size_t n)
{
	char *p = buf;
	char c;

	while (console_peek(&c, console, 1) == 0) {
		switch (c) {
		case '\004':
			console_getc(&c, console);
			return p - buf;
		default:
			if (((size_t)p - (size_t)buf) >= n)
				return p - buf;

			*p++ = c;
			console_getc(&c, console);
			break;
		}
	}

	return p - buf;
}

static ssize_t usart_write(void *cookie, const char *buf, size_t n)
{
	struct usart_console *console = cookie;
	size_t i;

	for (i = 0; i < n; ++i) {
		if (buf[i] == '\r')
			continue;

		if (buf[i] == '\n') {
			usart_send_blocking(console->dev, '\r');
		}

		usart_send_blocking(console->dev, buf[i]);
	};

	return i;
}

static int usart_get_irq_no(unsigned *irq_no, unsigned dev)
{
	if (!irq_no)
		return -1;

#if 0
	switch (dev) {
	case USART1: *irq_no = NVIC_USART1_IRQ; break;
	case USART2: *irq_no = NVIC_USART2_IRQ; break;
	default: return -1;
	}
#endif

	return 0;
}

static int usart_init(struct usart_console *console)
{
#if 0
	if (usart_get_irq_no(&console->irq_no, console->dev) < 0)
		return -1;

	usart_set_baudrate(console->dev, 115200);
	usart_set_databits(console->dev, 8);
	usart_set_parity(console->dev, USART_PARITY_NONE);
	usart_set_stopbits(console->dev, USART_STOPBITS_1);
	usart_set_mode(console->dev, USART_MODE_TX_RX);
	usart_set_flow_control(console->dev, USART_FLOWCONTROL_NONE);

	nvic_enable_irq(console->irq_no);
	usart_enable(console->dev);
	usart_enable_rx_interrupt(console->dev);
#endif

	return 0;
}

struct console *console_init(unsigned dev_id)
{
	cookie_io_functions_t fops = {
		.read = NULL,
		.write = usart_write,
		.seek = NULL,
		.close = NULL,
	};
	struct usart_console *console;

	console = usart + dev_id;

#if 0
	switch (dev_id) {
	case 0: console->dev = USART1; break;
	case 1: console->dev = USART2; break;
	default: return NULL;
	}
#endif

	console->cur = 0;
	console->next = 0;

	usart_init(console);

	console->console.fp = fopencookie(console, "w", fops);
	setvbuf(console->console.fp, NULL, _IONBF, 0);

	return &console->console;
}