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

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

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

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) {
}