#include <string.h>
#include <stdio.h>

#include "nav.h"
#include "net.h"
#include "err.h"
#include "parse.h"

/* history */

void nav_init(struct nav_state *ns) {
	memset(ns, 0, sizeof *ns);
	ns->histc = 1;
	doc_init(ns->histv);
	doc_add_text(ns->histv, "Type ? for command help.");
	ns->prot_default = PROT_GOPHER;
}

void nav_fini(struct nav_state *ns) {
	for (size_t i = 0; i < ns->histc; i++) {
		doc_fini(&ns->histv[i]);
	}
}

void nav_push(struct nav_state *ns, struct doc d) {
	while (ns->histc > ns->cur_doc + 1) {
		doc_fini(&ns->histv[--ns->histc]);
	}
	if (ns->histc == HIST_MAX) {
		doc_fini(ns->histv);
		memmove(ns->histv, &ns->histv[1], sizeof(struct doc) * (HIST_MAX - 1));
		memmove(ns->cur_ofs, &ns->cur_ofs[1], sizeof(size_t) * (HIST_MAX - 1));
		ns->histc--;
	}
	ns->cur_ofs[ns->histc] = 0;
	ns->histv[ns->histc++] = d;
	ns->cur_doc = ns->histc - 1;
}

void nav_prev(struct nav_state *ns) {
	if (ns->cur_doc > 0) ns->cur_doc--;
	nav_redraw(ns);
}

void nav_next(struct nav_state *ns) {
	if (ns->cur_doc + 1 < ns->histc) ns->cur_doc++;
	nav_redraw(ns);
}

/* paging */

size_t pg_lines(void) {
	return 24;
}

struct doc_line *nav_cur_line(struct nav_state *ns) {
	return doc_line_at(&ns->histv[ns->cur_doc], ns->cur_ofs[ns->cur_doc]);
}

int nav_line_up(struct nav_state *ns) {
	return !doc_line_prev(&ns->histv[ns->cur_doc], &ns->cur_ofs[ns->cur_doc]);
}

int nav_line_down(struct nav_state *ns) {
	return !doc_line_next(&ns->histv[ns->cur_doc], &ns->cur_ofs[ns->cur_doc]);
}

void nav_pg_up(struct nav_state *ns) {
	size_t lines = pg_lines() << 1;
	while (lines-- && nav_line_up(ns));
	nav_pg_down(ns);
}

#define MARGIN 8

void nav_pg_down(struct nav_state *ns) {
	size_t lines = pg_lines();
	while (lines--) {
		struct doc_line *l = nav_cur_line(ns);
		int n = 0;
		if (l->link != DOC_LINK_NONE) {
			n = printf("[%hu]", l->link + 1);
		}
		while (n++ < MARGIN) putchar(' ');
		fwrite(l->txt, 1, l->len, stdout);
		putchar('\n');
		if (!nav_line_down(ns)) break;
	}
}

void nav_redraw(struct nav_state *ns) {
	size_t lines = pg_lines();
	while (lines-- && nav_line_up(ns));
	nav_pg_down(ns);
}

/* network */

int nav_to(struct nav_state *ns, const char *url) {
	enum doc_type doct;
	struct addr adr;
	buf_t buf;
	if (net_addr(url, &adr, ns->prot_default)) {
		return -1;
	}
	ns->prot_default = adr.prot;
	if (net_fetch(&adr, &buf, &doct)) {
		return -1;
	}
	struct doc d;
	if (parse_doc(doct, &d, &buf)) {
		buf_free(&buf);
		return -1;
	}
	nav_push(ns, d);
	buf_free(&buf);
	nav_redraw(ns);
	return 0;
}

int nav_link_nr(struct nav_state *ns, unsigned long link_nr) {
	struct doc *d = &ns->histv[ns->cur_doc];
	const char *url = doc_get_link(d, link_nr);
	if (url) {
		puts(url);
		return nav_to(ns, url);
	} else {
		perr("invalid link number");
	}
	return 0;
}

void nav_prompt(struct nav_state *ns) {
	int m = doc_line_nextp(&ns->histv[ns->cur_doc], ns->cur_ofs[ns->cur_doc]);
	fputs(m ? "MORE* " : "* ", stdout);
}