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

#include "nav.h"
#include "net.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_FILE; /* change to PROT_GOPHER later */
}

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));
		ns->histc--;
	}
	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 (struct doc_line *)&ns->histv[ns->cur_doc].txt.buf[ns->cur_ofs[ns->cur_doc]];
}

int nav_line_up(struct nav_state *ns) {
	if (ns->cur_ofs[ns->cur_doc] > 0) {
		ns->cur_ofs[ns->cur_doc] -= nav_cur_line(ns)->prev; 
		return 1;
	} else {
		return 0;
	}
}

int nav_line_down(struct nav_state *ns) {
	struct doc_line *l = nav_cur_line(ns);
	if (ns->cur_ofs[ns->cur_doc] + sizeof(struct doc_line) + l->len < ns->histv[ns->cur_doc].txt.sz) {
		ns->cur_ofs[ns->cur_doc] += l->len + sizeof(struct doc_line); 
		return 1;
	} else {
		return 0;
	}
}

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

void nav_pg_down(struct nav_state *ns) {
	size_t lines = pg_lines();
	while (lines--) {
		struct doc_line *l = nav_cur_line(ns);
		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) {
	return 0;
}