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

#include "doc.h"
#include "net.h"
#include "err.h"

/* pagination */

size_t pg_lines() {
	return 24;
}

void pg_down(void) {
	size_t lines = pg_lines();
	while (lines--) doc_print_line();
}

void pg_up(void) {
	size_t lines = pg_lines() << 1;
	while (lines--) doc_back_line();
	pg_down();
}

void pg_redraw(void) {
	size_t lines = pg_lines();
	while (lines--) doc_back_line();
	pg_down();
}

/* navigation */

int nav_to(const char *url) {
	struct addr a;
	static enum protocol prot_default = PROT_FILE; /* change to gopher later */
	if (net_addr(url, &a, prot_default)) {
		return -1;
	}
	prot_default = a.prot;
	return 0;
}

int nav_link_nr(unsigned long link_nr) {
	return 0;
}

/* commands */

struct cmd {
	char ch;
	int (*fn)(const char *);
};

/* cmd is mutated when trimming strings
 * returns whether to quit */
int cmd_do(char *cmd) {
	switch (*cmd) {
	case 'q':
		puts("goodbye!");
		return 1;
	case '0': case '1': case '2': case '3': case '4':
	case '5': case '6': case '7': case '8': case '9':
		{
			errno = 0;
			unsigned long n = strtoul(cmd, NULL, 10);
			if (errno) {
				perr("invalid link number");
			} else if (nav_link_nr(n)) {
				perr("navigation failure");
			}
		}
		break;
	case 'b':
		pg_up();
		break;
	case '\0':
		pg_down();
		break;
	case 'r':
		pg_redraw();
		break;
	case 'g':
		if (nav_to(cmd + 1)) perr("navigation failure");
		break;
	default:
		perr("?");
		break;
	}
	return 0;
}


void cmd_trim(char *buf, size_t max) {
	size_t n = strlen(buf);
	while (n > 0 && isspace(buf[n - 1])) {
		buf[--n] = 0;
	}
	while (n > 1 && isspace(buf[1])) {
		memmove(&buf[0], &buf[1], n--);
	}
}

int cmd_get(char *buf, size_t n) {
	fputs("* ", stdout);
	return !!fgets(buf, n, stdin);
}

void init(void) {
	doc_init();
}

void fini(void) {
	doc_fini();
}

int main(void) {
	char cmd_buf[1024];
	init();
	atexit(fini);
	while (cmd_get(cmd_buf, sizeof cmd_buf)) {
		cmd_trim(cmd_buf, sizeof cmd_buf);
		if (cmd_do(cmd_buf)) {
			break;
		}
	}
	return 0;
}