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

#include <flash.h>
#include <macros.h>
#include <shell.h>

static void do_probe(const char *s);
static void do_read(const char *s);
static void do_write(const char *s);
static void do_erase(const char *s);

struct cmd cmds[] = {
	{ "probe", do_probe },
	{ "read", do_read },
	{ "write", do_write },
	{ "erase", do_erase },
	{ NULL, NULL },
};

static struct flash_dev *flash = NULL;

/* TODO: implement a parser for hex arrays that is more user-friendly.
 * Also implement dry runs for programmers. */
static void parse_hex(FILE *fp, char *buf, size_t len)
{
	size_t i;
	char s[3];

	for (i = 0; i < len; ++i) {
		memset(s, '\0', 3);

		while ((s[0] = getc(fp)) && !isxdigit(s[0]))
			putchar(s[0]);

		putchar(s[0]);

		while ((s[1] = getc(fp)) && !isxdigit(s[1]))
			putchar(s[1]);

		putchar(s[1]);

		*buf++ = strtoul(s, NULL, 16);
	}
}

static void print_hex_ascii(const char *buf, size_t len)
{
	size_t n, i;
	uint8_t c;

	for (; len; buf += n, len -= n) {
		n = min(len, 16);
		
		for (i = 0; i < 16; ++i) {
			c = (i < n) ? buf[i] : 0;
			printf("%x", c);
		}

		printf(" ");

		for (i = 0; i < 16; ++i) {
			c = (i < n) ? buf[i] : 0;
			printf("%c", isalnum(c) ? c : '.');
		}

		printf("\n");
	}
}

static char *prompt(const char *prefix)
{
	char *alloc, *line, *s;
	size_t nbytes = 0, nalloc_bytes = 16;
	char c;

	printf(prefix);

	if (!(line = malloc(nalloc_bytes)))
		return NULL;

	s = line;

	while ((c = getchar()) && c != '\n') {
		putchar(c);

		if (nbytes + 1 >= nalloc_bytes) {
			nalloc_bytes *= 2;

			if (!(alloc = realloc(line, nalloc_bytes)))
				goto err_free_line;

			line = alloc;
		}

		*s++ = c;
		nbytes++;
	}

	printf("\n");
	*s = '\0';

	return line;

err_free_line:
	free(line);
	return NULL;
}

static void do_probe(const char *s)
{
	(void)s;

	flash = flash_probe();
}

static void do_read(const char *s)
{
	char buf[256], *end = NULL;
	size_t addr, len, nbytes;

	if (!flash) {
		fprintf(stderr, "error: no flash device probed.\n");
		return;
	}

	if (strncmp(s, "0x", 2) == 0)
		s += 2;

	addr = strtoull(s, &end, 16);
	s = end;

	if (errno == EINVAL || errno == ERANGE)
		return;

	s += strspn(s, " \n");

	if (strncmp(s, "0x", 2) == 0)
		s += 2;

	len = strtoull(s, &end, 16);
	s = end;

	if (errno == EINVAL || errno == ERANGE)
		return;

	if (!len)
		return;

	while (len) {
		nbytes = min(len, 256);
		flash_read(flash, addr, buf, nbytes);
		print_hex_ascii(buf, nbytes);

		addr += nbytes;
		len -= nbytes;
	}
}

static void do_write(const char *s)
{
	char buf[256], *end = NULL;
	size_t addr, len, nbytes;

	if (!flash) {
		fprintf(stderr, "error: no flash device probed.\n");
		return;
	}

	if (strncmp(s, "0x", 2) == 0)
		s += 2;

	addr = strtoull(s, &end, 16);
	s = end;

	if (errno == EINVAL || errno == ERANGE)
		return;

	s += strspn(s, " \n");

	if (strncmp(s, "0x", 2) == 0)
		s += 2;

	len = strtoull(s, &end, 16);
	s = end;

	if (errno == EINVAL || errno == ERANGE)
		return;

	if (!len)
		return;

	while (len) {
		nbytes = (len > 256) ? 256 : len;
		parse_hex(stdin, buf, nbytes);
		printf("\n");
		print_hex_ascii(buf, nbytes);
		flash_write(flash, addr, buf, nbytes);

		addr += nbytes;
		len -= nbytes;
	}
}

static void do_erase(const char *s)
{
	char *end = NULL;
	size_t addr, len;

	if (!flash) {
		fprintf(stderr, "error: no flash device probed.\n");
		return;
	}

	if (strncmp(s, "0x", 2) == 0)
		s += 2;

	addr = strtoull(s, &end, 16);
	s = end;

	if (errno == EINVAL || errno == ERANGE)
		return;

	s += strspn(s, " \n");

	if (strncmp(s, "0x", 2) == 0)
		s += 2;

	len = strtoull(s, &end, 16);
	s = end;

	if (errno == EINVAL || errno == ERANGE)
		return;

	if (!len)
		return;

	flash_erase(flash, addr, len);
}

static void parse_cmd(const char *s)
{
	struct cmd *cmd;
	const char *args;
	char *key;
	size_t n;

	n = strcspn(s, " \n");
	key = strndup(s, n);

	args = s + n;
	args += strspn(args, " \n");

	for (cmd = cmds; cmd->key; cmd++) {
		if (strcmp(cmd->key, key) == 0)
			cmd->exec(args);
	}
}

void cmd_loop(const char *show)
{
	char *line;

	while (1) {
		line = prompt(show);
		parse_cmd(line);
		free(line);
	}
}