#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <errno.h>

#include "util.h"
#include "debug.h"
#include "config.h"

#define MAXLINE 128

static char menu[MAXLINE];

void
usage()
{
	printf("remu [FILE]\n");
	exit(0);
}

int
launch_menu(int *pfd, char *prompt)
{
	int pipefd[4];
	pid_t pid;
	if (pipe(pipefd))
		return 1;
	if (pipe(&pipefd[2])) {
		close(pipefd[0]);
		close(pipefd[1]);
		return 1;
	}

	pid = fork();

	switch (pid) {
	case -1:
		close(pipefd[0]);
		close(pipefd[1]);
		close(pipefd[2]);
		close(pipefd[3]);
		return 1;
	case 0:
		break;
	default:
		pfd[0] = pipefd[0];
		pfd[1] = pipefd[3];
		close(pipefd[1]);
		close(pipefd[2]);
		return 0;
	}

	/* Child process */
	close(pipefd[0]);
	close(pipefd[3]);

	if (dup2(pipefd[1], STDOUT_FILENO) == -1)
		exit(1);
	if (dup2(pipefd[2], STDIN_FILENO) == -1)
		exit(1);

	execvp(menu_cmd[0], (char **)menu_cmd);
	close(pipefd[1]);
	close(pipefd[2]);
	exit(0);
}

char *
nextline(char *c)
{
	while (*c != '\n')
		c++;

	return ++c;
}

char *
setline(char *p)
{
	char *end;
	end = nextline(p);
	end[-1] = 0;
	return end;
}

void
resetline(char *end)
{
	end[-1] = '\n';
}

char *
nextarg(char *c)
{
	while (*c == '\0')
		c++;

	return c;
}

char *
process_quoted(char *pnt)
{
	size_t off = 0;
	char *ret = NULL;
	pnt[0] = 0;
	pnt++;
	while (pnt[off] != '"') {
		if (pnt[off] == '\0' || pnt[off] == '\n')
			return NULL;

		if (pnt[off] == '\\') {
			if (pnt[off+1] == '\0' || pnt[off+1] == '\n')
				return NULL;
			off++;
		}
		pnt[0] = pnt[off];
		pnt++;
	}

	for (ret = &(pnt[off+1]); pnt != ret; pnt++)
		pnt[0] = 0;

	return ret;
}

char *
process_unquoted(char *pnt)
{
	size_t off = 0;
	char *ret = NULL;
	while (pnt[off] && pnt[off] != '\n') {
		if (pnt[off] == ' ') {
			ret = &pnt[off+1];
			break;
		}

		if (pnt[off] == '"')
			return NULL;

		if (pnt[off] == '\\') {
			if (pnt[off+1] == '\0' || pnt[off+1] == '\n')
				return NULL;
			off++;
		}
		pnt[0] = pnt[off];
		pnt++;
	}

	ret = ret ? ret : &pnt[off];

	for (; pnt != ret; pnt++)
		pnt[0] = 0;

	return ret;
}

char *
process_line(char *pnt)
{
	while (*pnt && *pnt != '\n') {
		if (*pnt == '"')
			pnt = process_quoted(pnt);
		else
			pnt = process_unquoted(pnt);

		if (pnt == NULL)
			return NULL;
	}

	return pnt;
}

unsigned int
preprocess(char *buf)
{
	char *pnt = buf;
	unsigned int line = 0;
	while (*pnt) {
		line++;
		if (*pnt == '#' || *pnt == '\n') {
			pnt = nextline(pnt);
			continue;
		}

		if (pnt[1] != ' ')
			return line;

		pnt[1] = 0;
		pnt = process_line(pnt+2);
		if (pnt == NULL)
			return line;
		pnt = nextline(pnt);
	}

	return 0;
}

int
submenu(char *line)
{
	char *e, *arg, *ea;
	arg = nextarg(line+2);
	ea = &arg[strlen(arg) - 1];
	if (*ea == '\n')
		return 1;

	arg = nextarg(ea+1);
	e = setline(line);
	strncpy(menu, arg, MAXLINE);
	menu[MAXLINE-1] = 0;
	resetline(e);
	return 0;
}

int
print(char *line)
{
	char *e, *arg, *ea;
	arg = nextarg(line+2);

	ea = &arg[strlen(arg) - 1];
	if (*ea != '\n' && *nextarg(ea+1) != '\n')
		arg = nextarg(ea+1);

	e = setline(line);
	printf("%s\n", arg);
	resetline(e);
	return 0;
}

int
run(char *line)
{
	char *e, *arg, *ea;
	arg = nextarg(line+2);

	ea = &arg[strlen(arg) - 1];
	if (*ea == '\n')
		return 1;

	arg = nextarg(ea+1);
	e = setline(line);
	if (execl("/bin/sh", "sh", "-c", arg, NULL))
		error("Error executing process: %s\n", strerror(errno));
	resetline(e);
	return 0;
}

int
main(int argc, char *argv[])
{
	char *buf, *stop, *pnt, *end, *mpnt, *line;
	unsigned int i;
	int pfd[2];
	FILE *f[2];
	char option[MAXLINE];

	strcpy(menu, default_menu);

	if (argc != 2)
		usage();

	buf = f_read(argv[1]);
	if (buf == NULL) {
		fprintf(stderr, "Couldn't read file %s\n", argv[1]);
		return 1;
	}

	stop = &buf[strlen(buf)];
	if (stop == buf) {
		fprintf(stderr, "Wrong format in %s: Empty file\n", argv[1]);
		return 1;
	} else if (stop[-1] != '\n') {
		fprintf(stderr, "Wrong format in %s: Missing EOL at the end of the file\n", argv[1]);
		return 1;
	}

	if (i = preprocess(buf)) {
		fprintf(stderr, "Wrong format in %s:%u\n", argv[1], i);
		return 1;
	}


	while (1) {
		for (pnt = buf; pnt != stop; pnt = nextline(pnt)) {
			if (*pnt != 'm')
				continue;
			pnt = nextarg(pnt+1);
			end = setline(pnt);

			if (strcmp(menu, pnt) == 0)
				break;
			resetline(end);
		}

		if (pnt == stop) {
			fprintf(stderr, "Couldn't find menu %s in file %s\n", menu, argv[1]);
			return 1;
		}

		resetline(end);

		/* Query option */
		if (launch_menu(pfd, NULL)) {
			fprintf(stderr, "Couldn't open the menu\n");
			return 1;
		}

		f[0] = fdopen(pfd[0], "r");
		f[1] = fdopen(pfd[1], "w");

		if (f[0] == NULL || f[1] == NULL) {
			fprintf(stderr, "Couldn't open the menu\n");
			return 1;
		}

		mpnt = nextline(pnt);
		for (pnt = mpnt; pnt != stop; pnt = nextline(pnt)) {
			if (*pnt == 'm')
				break;

			if (*pnt == '\n' || *pnt == '#')
				continue;

			pnt = nextarg(pnt+1);
			end = setline(pnt);
			fprintf(f[1], "%s\n", pnt);
			resetline(end);
		}

		fclose(f[1]);
		close(pfd[1]);

		if (fgets(option, MAXLINE, f[0]) == NULL) {
			fprintf(stderr, "Couldn't open the menu\n");
			return 1;
		}
		option[strlen(option)-1] = 0;

		for (line = mpnt; line != stop; line = nextline(line)) {
			if (*line == 'm')
				break;

			if (*line == '\n' || *line == '#')
				continue;

			pnt = nextarg(line+1);

			if (*pnt == '\n') {
				fprintf(stderr, "Wrong format in %s: Not enough arguments\n", argv[1]);
				return 1;
			}

			end = setline(pnt);
			if (strcmp(pnt, option) == 0)
				break;
			resetline(end);
		}

		/* No option selected */
		if (*line == 'm' || line == stop)
			break;

		resetline(end);
		switch (line[0]) {
		case 's':
			if (submenu(line)) {
				fprintf(stderr, "Wrong format in %s: Not enough arguments\n", argv[1]);
				return 1;
			}
			break;
		case 'p':
			print(line);
			return 0;
		case 'r':
			if (run(line)) {
				fprintf(stderr, "Wrong format in %s: Not enough arguments\n", argv[1]);
				return 1;
			}
			return 0;
		default:
			return 0;
		}
	}
}