#include <sys/types.h>
#include <dirent.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <errno.h>

#include "parse.h"
#include "pagemap.h"

static struct maps_list *alloc_maplist(void)
{
	struct maps_list *map;

	map = malloc(sizeof *map);
	if (map == NULL)
		goto err;

	memset(map, 0, sizeof(*map));
	INIT_LIST_HEAD(&map->list);
err:
	return map;
}

static struct maps *alloc_map(void)
{
	struct maps *map;

	map = malloc(sizeof *map);
	if (map == NULL)
		goto err;

	memset(map, 0, sizeof(*map));
	INIT_LIST_HEAD(&map->list);
err:
	return map;
}

static struct maps *parse_maps(FILE *file, int pid)
{
	struct maps *the_map = NULL;
	char line[1024];
	int ret;

	while(fgets(line, sizeof(line), file)) {
		struct maps *map = alloc_map();
		unsigned long start, end;
		char name[1024];

		if (map == NULL)
			return 0;

		if (the_map == NULL)
			the_map = map;

		ret = sscanf(line, "%lx-%lx %*s %*s %*s %*s %s",
			     &start, &end, name);

		printf("%x, start %lx, end %lx, str: %s\n",
			ret, start, end, ret >= 3 ? name : "");

		if (ret < 2) {
			printf("Error reading input: %s\n", line);
			break;
		}

		map->start = start;
		map->end = end;
		map->size = end - start;
		map->pid = pid;

		if (ret >= 3)
			strncpy(map->name, name, sizeof(map->name));

		list_add_tail(&map->list, &the_map->list);
	}

	return the_map;
}

static void clear_pageframe(struct pageframe *pf)
{
	memset(pf, 0, sizeof(*pf));
}

static struct pageframe *alloc_pageframe(void)
{
	struct pageframe *pageframe;

	pageframe = malloc(sizeof *pageframe);
	if (pageframe == NULL)
		goto err;

	clear_pageframe(pageframe);
err:
	return pageframe;
}

#define BITRANGE(first, last) (((2ll << (last - first)) - 1) << first)

static void pageframe_to_struct(unsigned long long p, struct pageframe *pf)
{
	pf->page_present = !!(BITRANGE(63, 63) & p);
	pf->page_swapped = !!(BITRANGE(62, 62) & p);
	pf->page_shift	 =   (BITRANGE(55, 60) & p) >> 55;
	pf->pfn		 =   (BITRANGE(0, 54) & p);
	pf->swap_type	 =   (BITRANGE(0, 4) & p);
	pf->swap_offset	 =   (BITRANGE(5, 54) & p) >> 5;
#if 0
	printf("pfn: %lx shift: %d present: %d swapped %d\n",
		pf->pfn, pf->page_shift, pf->page_present, pf->page_swapped);
#endif
}

static int compare_pageframe(struct bintree *at, struct bintree *bt)
{
	struct pageframe *a, *b;
	a = tree_to_pageframe(at);
	b = tree_to_pageframe(bt);

	return a->pfn - b->pfn;
}

struct bintree_ops pageframe_ops = {
	.compare = compare_pageframe,
};

/* Read data from the /proc/pid/pagemap file */
static int parse_pageframe(FILE *file, struct pageframe *pf_tree,
			struct maps *maps, int add_to_tree)
{
	struct maps *map;
	struct maps_list *tmp;
	struct pageframe *match, *pageframe = NULL;
	long start, len, i;
	unsigned long long pf;
	int ret, error;

	/* Go through the list of allocated memory areas */
	list_for_each_entry(map, &maps->list, list) {
		start = map->start >> (PAGE_SHIFT - 3);
		len = map->size >> (PAGE_SHIFT - 3);

		printf("start: %lx len %lx: name: %s\n",
			start, len, map->name);

		ret = fseek(file, start, SEEK_SET);
		if (ret) {
			error = errno;
			fprintf(stderr, "Error seeking to %lx: %s\n", start,
				strerror(error));
			continue;
			return -1;
		}

		for (i = 0; i < len; i++) {
			ret = fread(&pf, 1, sizeof(pf), file);
			if (ret != sizeof(pf)) {
				error = errno;
				fprintf(stderr, 
					"Error reading %ld bytes, got %d: %s\n",
					sizeof(pf), ret, strerror(errno));
				continue;
				return -1;
			}
			if (!pageframe)
				pageframe = alloc_pageframe();

			pageframe_to_struct(pf, pageframe);

			if (add_to_tree) {
				match = tree_to_pageframe(
					bintree_add(&pf_tree->tree,
						&pageframe->tree,
						&pageframe_ops));
			} else {
				match = tree_to_pageframe(
					bintree_find(&pf_tree->tree,
						&pageframe->tree,
						&pageframe_ops));
			}

			if (match == NULL)
				continue;

			if (match == pageframe)
				pageframe = NULL;

			match->refcount++;
			/*
			 * Add a link from the physical page to this
			 * process's page map
			 */
			if (!match->ml) {
				match->ml = alloc_maplist();
				match->ml->map = map;
			} else {
				tmp = alloc_maplist();
				tmp->map = map;
				list_add(&match->ml->list, &tmp->list);
			}
		}
	}

	return 0;
}

void read_pageframe(int pid, struct pageframe *pageframe, int add_to_tree)
{
	struct maps *maps;
	FILE *file;
	int error;
	char path[512];

	snprintf(path, sizeof(path), "/proc/%d/maps", pid);
	file = fopen(path, "rb");

	if (!file)
		goto err_out;

	maps = parse_maps(file, pid);

	snprintf(path, sizeof(path), "/proc/%d/pagemap", pid);
	file = fopen(path, "rb");

	if (!file)
		goto err_out;

	parse_pageframe(file, pageframe, maps, add_to_tree);

	return;
err_out:
	error = errno;
	fprintf(stderr, "Failed to open file %s: %s\n", path, strerror(error));

	return;
}

static int get_next_pid(void)
{
	static DIR *dir = NULL;
	struct dirent *dirent;
	int error;

	if (!dir) {
		dir = opendir("/proc");
		if (!dir) {
			error = errno;
			printf("Failed to open /proc directory: %s\n",
				strerror(error));
			return -1;
		}
	}

restart:
	dirent = readdir(dir);
	if (!dirent) {
		if (errno == 0) {
			closedir(dir);
			dir = NULL;
			return 0;
		}
		error = errno;
		printf("Failed to read directory: %s\n", strerror(error));
		return -1;
	}

	printf("%s\n", dirent->d_name);
	if (dirent->d_name[0] < '0' || dirent->d_name[0] > '9')
		goto restart;

	return atoi(dirent->d_name);
}

void scan_all_pids(struct pageframe *pf, int interesting_pid)
{
	int pid;

	read_pageframe(interesting_pid, pf, 1);

	while(1) {
		pid = get_next_pid();
		if (pid <= 0)
			break;
		read_pageframe(pid, pf, 0);
	}
}