#if 0

bin="$(mktemp)"
cc -o "$bin" -x c "$(realpath $0)"
"$bin"

exit 0
#endif

/*
TODO:
- fix: move_and... should be able to read tokens in quotes (with spaces)
- readline capabilities
*/

#include <stdint.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/wait.h>

#define MIN(a, b) ((a) < (b) ? (a) : (b))
#define MAX(a, b) ((a) > (b) ? (a) : (b))

#define LINEMAXLEN 10000

#define ALGFILE "/home/sebastiano/box/speedcubing/bld/algs/algs.txt"
#if 0
#define INFILE "/home/sebastiano/box/speedcubing/bld/algs/algs.backup"
#else
#define INFILE ALGFILE
#endif
#define EDITOR "vi"

char *alias[256][10] = {
	['a'] = { "FU", "FUL", "FLU", "Fu", "Ful", "Flu", "FUl", NULL },
	['b'] = { "UF", "UBL", "ULB", "Ur", "Ufr", "Ulb", "URb", NULL },
	['c'] = { "UL", "UFL", "ULF", "Ul", "Ufl", "Ulf", "ULf",
	    "corners", NULL },
	['d'] = { "UB", "UBR", "URB", "Ub", "Ubr", "Urb", "UBl", NULL },
	['e'] = { "FD", "FDR", "FRD", "Fd", "Frd", "Fdr", "FDr",
	    "edges", NULL },
	['f'] = { "RD", "RBD", "RDB", "Rd", "Rdb", "Rbd", "RDb",
	    "2flips", NULL },
	['g'] = { "LD", "LDF", "LFD", "Ld", "Ldf", "Lfd", "LDf", NULL },
	['h'] = { NULL },
	['i'] = { "FR", "FUR", "FRU", "Fr", "Fur", "Fru", "FRu", NULL },
	['j'] = { "LU", "LUF", "LFU", "Lu", "Luf", "Lfu", "LUb", NULL },
	['k'] = { "RB", "RUB", "RBU", "Rb", "Rub", "Rbu", "RBu", NULL },
	['l'] = { "DF", "DFR", "DRF", "Df", "Dfr", "Drf", "DFl", NULL },
	['m'] = { "DB", "DBR", "DRB", "Db", "Dbr", "Drb", "DBr",
	    "midges", NULL },
	['n'] = { "DR", "DFL", "DLF", "Dr", "Dfl", "Dlf", "DRf", NULL },
	['o'] = { "FL", "FLD", "FDL", "Fl", "Fdl", "Fld", "FLd", NULL },
	['p'] = { "DL", "DLB", "DBL", "Dl", "Dbl", "Dlb", "DLb",
	    "parity", NULL },
	['q'] = { NULL },
	['r'] = { "BU", "BUR", "BRU", "Bu", "Bur", "Bru", "BUr", NULL },
	['s'] = { "BD", "BUL", "BLU", "Bd", "Bul", "Blu", "BDl", NULL },
	['t'] = { "BL", "BLD", "BDL", "Bl", "Bdl", "Bld", "BLu",
	    "tcenters", NULL },
	['u'] = { "BR", "BRD", "BDR", "Br", "Brd", "Bdr", "BRd", NULL },
	['v'] = { "LF", "LUB", "LBU", "Lf", "Lub", "Lbu", "LFu", NULL },
	['w'] = { "LB", "LBD", "LDB", "Lb", "Ldb", "Lbd", "LBd",
	    "wings", NULL },
	['x'] = { "RU", "RFU", "RUF", "Ru", "Rfu", "Ruf", "RUf",
	    "xcenters", NULL },
	['y'] = { "UR", "UFR", "URF", "Uf", "Ubl", "Ulb", "UFr", NULL },
	['z'] = { "RF", "RDF", "RFD", "Rf", "Rdf", "Rfd", "RFd", NULL },
	['3'] = { "3twists", NULL },
};

struct node {
	char *key;
	size_t mchildren;
	size_t nchildren;
	struct node *child;
};

enum command {
	BACK,
	EDIT,
	EXPORT,
	HELP,
	PRINT,
	QUIT,
	RENAME,
	NONE,
	UNKNOWN
};

char command_aliases[] = {
	[BACK] = 'b',
	[EDIT] = 'e',
	[EXPORT] = 'x',
	[HELP] = 'h',
	[PRINT] = 'p',
	[QUIT] = 'q',
	[RENAME] = 'r',
};

const char *HELPSTR =
"This program can be used interactively to navigate and modify a collection\n"
"of data organized as a tree. This data is saved to a file in a custom\n"
"text-based format. At any given time, the program points to one node in the\n"
"tree (the current node), and the user can give instructions.\n"
"\n"
"An instruction has the following syntax: [movement] [command]\n"
"\n"
"A movement can be specified either by a space-separated list of keys,\n"
"where keys containing spaces must be wrapped in double quotes, or by a\n"
"single word, each letter of which is translated to a key using the\n"
"alias table. Only if a word does not match the key of any child of the\n"
"current node is it interpreted as a list of aliases.\n"
"\n"
"Commands are a single letter preceded by a colon. For example ':q' quits\n"
"the program. See below for a list of commands.\n"
"\n"
"If only a command is specified, it is exectued on the current node.\n"
"\n"
"If only a movement is specified, the current node is changed to the one\n"
"specified by the movement. If the new current node is terminal, i.e. all\n"
"its children are childless, a ':p' command is implied and is exectued as\n"
"if 'movement :p' was given.\n"
"\n"
"If both a movement and a command are specified, the movement is applied,\n"
"then the command is exectued, and finally the current node is changed\n"
"back to the previous node.\n"
"\n"
"List of commands:\n"
"  - :b Move back to the parent node (usually used without movement).\n"
"  - :e Edit current node. Can be used to add or remove children.\n"
"  - :x Export to csv.\n"
"  - :h Print this help message.\n"
"  - :p Print the key of the node.\n"
"  - :q Quit (exit the program).\n"
"  - :r Rename (edit the key of the current node).\n"
;

int is_space(char c) {
	return c == ' ' || c == '\t' || c == '\n';
}

int has_spaces(const char *k) {
	for (const char *c = k; *c; c++)
		if (is_space(*c))
			return 1;
	return 0;
}

int is_whitespace_only(const char *k) {
	for (const char *c = k; *c; c++)
		if (!is_space(*c))
			return 0;
	return 1;
}

void write_key(FILE *f, const char *k) {
	if (has_spaces(k))
		fprintf(f, "\"%s\"", k);
	else
		fprintf(f, "%s", k);
}

void write_indent(FILE *f, size_t n) {
	for (size_t i = 0; i < n; i++)
		fprintf(f, "  ");
}

int is_terminal(const struct node *n) {
	for (size_t i = 0; i < n->nchildren; i++)
		if (n->child[i].nchildren > 0)
			return 0;
	return 1;
}

void write_node(FILE *f, const struct node *n, size_t ntabs, int s) {
	write_indent(f, ntabs);
	fprintf(f, "{ ");
	write_key(f, n->key);
	if (is_terminal(n)) {
		for (size_t i = 0; i < n->nchildren; i++) {
			fprintf(f, " ");
			write_key(f, n->child[i].key);
		}
		fprintf(f, " }\n");
	} else {
		fprintf(f, "\n");
		for (size_t i = 0; i < n->nchildren; i++) {
			if (s && !is_terminal(&n->child[i])) {
				write_indent(f, ntabs+1);
				fprintf(f, "{ ");
				write_key(f, n->child[i].key);
				fprintf(f, " { ... } }\n");
			} else {
				write_node(f, &n->child[i], ntabs+1, s);
			}
		}
		write_indent(f, ntabs);
		fprintf(f, "}\n");
	}
}

void delete_node(struct node *n) {
	if (n->child) {
		for (size_t i = 0; i < n->nchildren; i++)
			delete_node(&n->child[i]);
		free(n->child);
	}
	n->nchildren = n->mchildren = 0;
	free(n->key);
}

void grow_children_if_needed(struct node *n) {
	if (n->nchildren == n->mchildren) {
		size_t m = MAX(1, 2*n->mchildren);
		n->child = realloc(n->child, m * sizeof(struct node));
		memset(n->child + n->nchildren, 0,
		    (m - n->nchildren) * sizeof(struct node));
		n->mchildren = m;
	}
}

void add_child(struct node *n, struct node c) {
	grow_children_if_needed(n);
	n->child[n->nchildren++] = c;
}

void parse_error(struct node *n, const char *a, size_t *i, size_t len) {
	if (*i == len)
		printf("Error: end of file reached unexpectedly.\n");
	else
		printf("Error: unexpected '%c' at position %zu.\n",
		    a[*i], *i);

	if (n != NULL) {
		printf("Error occurred when reading node with key: ");
		write_key(stdout, n->key);
		printf("\n");
	}
}

int read_key(struct node *n, const char *a, size_t *i, size_t len) {
	while (is_space(a[*i])) (*i)++;
	if (a[*i] == '{') {
		printf("Error: missing key at %zu\n", *i);
		return 0;
	}
	bool q = a[*i] == '"';
	if (q) (*i)++;
	size_t start = *i;
	while (*i < len && ((q && a[*i] != '"') || (!q && !is_space(a[*i]))))
		(*i)++;
	size_t klen = *i - start;
	n->key = malloc(klen+1);
	memcpy(n->key, a+start, klen);
	n->key[klen] = '\0';
	if (*i == len) {
		printf("Error: EOF in key starting at %zu "
		       "(begins with '%.5s').\n", start, n->key);
		return 0;
	}
	if (q)
		(*i)++; // Skip quote
	return 1;
}

int read_node(struct node *n, const char *a, size_t *i, size_t len) {
	while (is_space(a[*i])) (*i)++;
	if (a[*i] != '{') {
		printf("Error: expected '{' at %zu, got '%c'.\n", *i, a[*i]);
		return 0;
	}
	(*i)++;
	if (!read_key(n, a, i, len))
		return 0;
	for (; *i < len; (*i)++) {
		switch (a[*i]) {
		case ' ':
		case '\t':
		case '\n':
			continue;
		case '}':
			(*i)++;
			return 1;
		case '{':
			grow_children_if_needed(n);
			read_node(&n->child[n->nchildren++], a, i, len);
			break;
		default:
			grow_children_if_needed(n);
			read_key(&n->child[n->nchildren++], a, i, len);
		}
	}
	return 1;
}

int read_file(struct node *n) {
	FILE *f = fopen(INFILE, "r");
	fseek(f, 0, SEEK_END);
	size_t fsize = ftell(f);
	fseek(f, 0, SEEK_SET);

	char *a = malloc(fsize);
	fread(a, 1, fsize, f);

	size_t i = 0;
	int result = read_node(n, a, &i, fsize);

	free(a);
	return result;
}

void write_tree(const struct node *root) {
	FILE *f = fopen(ALGFILE, "w");
	write_node(f, root, 0, 0);
	/* printf("Data written to %s.\n", ALGFILE); */
	fclose(f);
}

struct node *match_children(const char *w, size_t wlen, const struct node *n) {
	for (size_t i = 0; i < n->nchildren; i++) {
		if (strlen(n->child[i].key) != wlen)
			continue;
		if (!strncmp(w, n->child[i].key, wlen))
			return &n->child[i];
	}
	return NULL;
}

int move_stack(const char *w, size_t wlen, struct node *stack[], size_t *top) {
	struct node *c = match_children(w, wlen, stack[*top]);
	if (c) {
		stack[++(*top)] = c;
		return 1;
	}

	int matched = 1;
	for (size_t i = 0; matched && i < wlen; i++) {
		matched = 0;
		if ((w[i] < 'a' || w[i] > 'z') && (w[i] < '0' && w[i] > '9'))
			return 1;
		for (size_t j = 0; alias[(unsigned)w[i]][j]; j++) {
			c = match_children(alias[(unsigned)w[i]][j],
			    strlen(alias[(unsigned)w[i]][j]), stack[*top]);
			if (c) {
				stack[++(*top)] = c;
				matched = 1;
				break;
			}
		}
	}
	return matched;
}

int move_and_parse_command(const char *line,
    struct node *stack[], size_t *stack_top) {
	size_t wstart, wend = 0;
	while (line[wend] && line[wend] != ':') {
		while (is_space(line[wend])) wend++;
		wstart = wend;
		while (!is_space(line[wend])) wend++;
		if (!move_stack(line+wstart, wend-wstart, stack, stack_top)) {
			printf("Invalid key '");
			for (size_t i = wstart; i < wend; i++)
				printf("%c", line[i]);
			printf("'.\n");
			return NONE;
		}
		while (is_space(line[wend])) wend++;
	}

	if (!line[wend])
		return is_terminal(stack[*stack_top]) ? PRINT : NONE;
	for (size_t i = 0; i < NONE; i++)
		if (command_aliases[i] == line[wend+1])
			return i;
	printf("Unknown command.\n");
	return UNKNOWN;
}

void print_node(struct node *n) {
	if (is_terminal(n)) {
		for (size_t i = 0; i < n->nchildren; i++)
			printf("%s\n", n->child[i].key);
	} else {
		write_node(stdout, n, 0, 1);
	}
}

void delete_child(struct node *n, size_t i) {
	delete_node(&n->child[i]);
	for (size_t j = i+1; j < n->nchildren; j++)
		n->child[j-1] = n->child[j];
	n->nchildren--;
}

void replace_child(struct node *n, size_t i, size_t j) {
	if (i >= j) {
		printf("Cannot replace child in wrong order.\n");
		return;
	}
	delete_node(&n->child[j]);
	n->child[j] = n->child[i];
	n->nchildren--;
	for (size_t k = i; k < n->nchildren; k++)
		n->child[k] = n->child[k+1];
}

void remove_duplicate_children(struct node *n) {
	for (size_t i = 0; i < n->nchildren; i++) {
		for (size_t j = i + 1; j < n->nchildren; j++) {
			if (!strcmp(n->child[i].key, n->child[j].key)) {
				replace_child(n, i, j);
				i--;
				j--;
				break;
			}
		}
	}
}

int edit(struct node *n) {
	/* create tmp file with algs, one by line */
	char path[50] = "/tmp/alg.XXXXXXX";
	int fd = mkstemp(path);
	if (fd == -1) {
		printf("Could not create tmp file for editing.\n");
		return 0;
	}
	FILE *tmp = fdopen(fd, "w+");
	for (size_t i = 0; i < n->nchildren; i++)
		fprintf(tmp, "%s\n", n->child[i].key);
	fclose(tmp);
	close(fd);

	/* fork and open editor */
	int cpid = fork();
	if (cpid == 0) {
		execlp(EDITOR, EDITOR, path, (char *)NULL);
	} else {
		wait(NULL);
		tmp = fopen(path, "r");
		if (!tmp) {
			printf("Could not read edited algs, aborting.\n");
			return 0;
		}

		size_t oldn = n->nchildren;

		/* Append the new children */
		char line[LINEMAXLEN];
		for (size_t i = 0; fgets(line, LINEMAXLEN, tmp); i++) {
			size_t len = strlen(line);
			struct node c = {0};
			c.key = malloc(len);
			memcpy(c.key, line, len);
			c.key[len-1] = '\0';
			add_child(n, c);
		}
		fclose(tmp);

		/* Delete removed node, asking for confirmation */
		for (size_t i = oldn-1; i != SIZE_MAX; i--) {
			int found = 0;
			for (size_t j = oldn; j < n->nchildren; j++)
				found = found ||
				    !strcmp(n->child[i].key, n->child[j].key);
			if (!found) {
				int d = 1;
				if (!is_terminal(n)) {
					printf("Confirm delete node ");
					write_key(stdout, n->child[i].key);
					printf("? [y/N] ");
					fflush(stdout);
					fgets(line, LINEMAXLEN, stdin);
					d = line[0] == 'y' || line[0] == 'Y';
				}
				if (d) {
					delete_child(n, i);
					oldn--;
				}
			}
		}

		remove_duplicate_children(n);
	}

	return 1;
}

int is_table(const struct node *n) {
	return n->nchildren != 0 &&
	       n->child[0].nchildren != 0 &&
	       n->child[0].child[0].nchildren != 0 &&
	       is_terminal(&(n->child[0].child[0]));
}

struct node *find_child(const struct node *n, const char *k) {
	for (size_t i = 0; i < n->nchildren; i++) {
		if (!strcmp(n->child[i].key, k))
			return &n->child[i];
	}
	return NULL;
}

void export(const struct node *n) {
	if (!is_table(n)) {
		printf("Cannot export: not a table.\n");
		return;
	}

	char fname[50];
	sprintf(fname, "%.45s.csv", n->key);
	FILE *f = fopen(fname, "w");

	/* Print first row (header) */
	fprintf(f, "\"\",");
	for (size_t i = 0; i < n->nchildren; i++)
		fprintf(f, "\"%s\",", n->child[i].key);
	fprintf(f, "\n");

	/* Fill the rest of the table */
	for (size_t i = 0; i < n->nchildren; i++) {
		fprintf(f, "\"%s\",", n->child[i].key);
		for (size_t j = 0; j < n->nchildren; j++) {
			const struct node *c = find_child(
			    &n->child[i], n->child[j].key);
			if (c == NULL || c->nchildren == 0)
				fprintf(f, "\"\",");
			else
				fprintf(f, "\"%s\",", c->child[0].key);
		}
		fprintf(f, "\n");
	}

	fclose(f);
}

int rename_node(struct node *n) {
	printf("Old key: ");
	write_key(stdout, n->key);
	printf("\nNew key (empty line to cancel): ");

	char k[LINEMAXLEN];
	size_t len = fgets(k, LINEMAXLEN, stdin) == NULL ? 0 : strlen(k)-1;
	k[len] = '\0'; /* Replace \n with \0 */
	if (len == 0) {
		printf("\nRenaming cancelled, old key kept.\n");
		return 0;
	} else {
		if (strlen(n->key) < len)
			n->key = realloc(n->key, len+1);
		memcpy(n->key, k, len+1);
		return 1;
	}
}

void main_loop(struct node *root) {
	char line[LINEMAXLEN];
	struct node *stack[20] = { root };
	size_t stack_top = 0;
	while (1) {
		for (size_t i = 0; i <= stack_top; i++) {
			write_key(stdout, stack[i]->key);
			printf(" ");
		}
		printf("> ");
		fflush(stdout);
		if (fgets(line, LINEMAXLEN, stdin) == NULL) {
			printf("\n");
			return;
		}
		if (is_whitespace_only(line)) continue;
		int oldtop = stack_top;
		int command = move_and_parse_command(line, stack, &stack_top);

		switch (command) {
			case BACK:
				if (stack_top > 0)
					oldtop = --stack_top;
				else
					printf("Already at top of stack.\n");
				break;
			case EDIT:
				if(edit(stack[stack_top]))
					write_tree(root);
				break;
			case EXPORT:
				export(stack[stack_top]);
				break;
			case HELP:
				printf("%s", HELPSTR);
				break;
			case PRINT:
				print_node(stack[stack_top]);
				break;
			case QUIT:
				return;
			case RENAME:
				if (rename_node(stack[stack_top]))
					write_tree(root);
				break;
			case NONE:
				oldtop = stack_top;
			case UNKNOWN:
			default:
				break;
		}
		stack_top = oldtop;
	}
}

int main() {
	struct node root = {0};
	if (!read_file(&root)) {
		printf("Error reading data from file.\n");
		return 1;
	}
	printf("Data read from %s\n", INFILE);

	main_loop(&root);

	delete_node(&root);
	return 0;
}