#include "bin.h"
#include "commands.h"
#include "b-tree.h"

#include <blue/cmd.h>
#include <stdio.h>
#include <stdlib.h>
#include <zstd.h>

#define INVALID_NODE_PTR    0xFFFF

#define ORDER               6
#define MAX                 (ORDER - 1)
#define MIN                 (MAX / 2)

enum {
	ARG_INPATH,
	OPT_OUTPATH,
	OPT_OUTPATH_PATH,
};

struct entry
{
	uint32_t key;
	uint32_t value;
};

struct node {
	uint16_t nr_entries;
	struct entry entries[MAX];
	uint16_t children[ORDER];
};

struct data_tree {
	struct b_tree base;
	FILE *fp;
};

static int node_init(struct node *n)
{
	memset(n, 0x0, sizeof * n);

	for (int i = 0; i < ORDER; i++) {
		n->children[i] = INVALID_NODE_PTR;
	}

	return 0;
}

static int tree_get_node(struct b_tree *p, unsigned long id, b_tree_node *n)
{
	struct data_tree *tree = (struct data_tree *)p;
	size_t offset = (id * sizeof(struct node));
	fseek(tree->fp, offset, SEEK_SET);
	size_t r = fread(n, sizeof(struct node), 1, tree->fp);
	return r == 1 ? 0 : -1;
}

static int tree_put_node(struct b_tree *p, unsigned long id, const b_tree_node *n)
{
	struct data_tree *tree = (struct data_tree *)p;
	size_t offset = (id * sizeof(struct node));
	fseek(tree->fp, offset, SEEK_SET);
	size_t r = fwrite(n, sizeof(struct node), 1, tree->fp);
	return r == 1 ? 0 : -1;
}

static long tree_alloc_node(struct b_tree *p)
{
	struct data_tree *tree = (struct data_tree *)p;
	size_t pos = ftell(tree->fp);
	fseek(tree->fp, 0, SEEK_END);
	size_t len = ftell(tree->fp);

	struct node n;
	node_init(&n);

	fwrite(&n, sizeof n, 1, tree->fp);

	fseek(tree->fp, pos, SEEK_SET);

	len /= sizeof(struct node);

	return (long)len;
}

static unsigned long node_get_nr_entries(b_tree_node *n)
{
	struct node *node = (struct node *)n;
	return node->nr_entries;
}

static void node_set_nr_entries(b_tree_node *n, unsigned long val)
{
	struct node *node = (struct node *)n;
	node->nr_entries = val;
}

static b_tree_node_entry *node_get_entries(b_tree_node *n)
{
	struct node *node = (struct node *)n;
	return (b_tree_node_entry *)node->entries;
}

static uint16_t *node_get_children(b_tree_node *n)
{
	struct node *node = (struct node *)n;
	return node->children;
}

static int entry_compare(const b_tree_node_entry *e0, const b_tree_node_entry *e1)
{
	struct entry *a = (struct entry *)e0, *b = (struct entry *)e1;

	if (a->key < b->key) {
		return -1;
	}

	if (a->key > b->key) {
		return 1;
	}

	return 0;
}

static const struct b_tree_ops ops = {
	.node_size = sizeof(struct node),
	.entry_size = sizeof(struct entry),

	.tree_get_node = tree_get_node,
	.tree_put_node = tree_put_node,
	.tree_alloc_node = tree_alloc_node,

	.node_get_nr_entries = node_get_nr_entries,
	.node_set_nr_entries = node_set_nr_entries,
	.node_get_entries = node_get_entries,
	.node_get_children = node_get_children,

	.entry_compare = entry_compare,
};

void indent(int depth)
{
	for (int i = 0; i < depth; i++) {
		fputs("  ", stdout);
	}
}

int node_print(struct b_tree *tree, struct node *n, int depth)
{
	int c_before = (n->nr_entries + 1) / 2;
	int c_after = n->nr_entries + 1 - c_before;
	int i_before = 0;
	int i_after = i_before + c_before;

	int err = 0;

	for (unsigned short i = 0; i < c_before; i++) {
		struct node child;
		int index = i_before + i;

		if (n->children[index] == INVALID_NODE_PTR) {
			// indent(depth + 1);
			continue;
		}

		err = tree_get_node(tree, n->children[index], (b_tree_node *)&child);
		if (err != 0) {
			printf("ERR: failed to read node %u\n",
				n->children[index]);
			continue;
		}

		node_print(tree, &child, depth + 1);
	}

	indent(depth);
	printf("[");

	for (unsigned short i = 0; i < n->nr_entries; i++) {
		if (i > 0) {
			printf(" ");
		}

		printf("%d", n->entries[i].key);
	}

	printf("]\n");

	for (unsigned short i = 0; i < c_after; i++) {
		struct node child;
		int index = i_after + i;

		if (n->children[index] == INVALID_NODE_PTR) {
			// indent(depth + 1);
			continue;
		}

		err = tree_get_node(tree, n->children[index], (b_tree_node *)&child);
		if (err != 0) {
			printf("ERR: failed to read node %u\n",
				n->children[index]);
			continue;
		}

		node_print(tree, &child, depth + 1);
	}

	return 0;
}

int tree_print(struct b_tree *tree)
{
	struct node root;
	tree_get_node(tree, 0, (b_tree_node *)&root);
	return node_print(tree, &root, 0);
}

static int create(
	const b_command *self,
	const b_arglist *opt,
	const b_array *args)
{
	const char *in_path = NULL, *out_path = NULL;

	b_arglist_get_string(
		opt,
		B_COMMAND_INVALID_ID,
		ARG_INPATH,
		0,
		&in_path);
	b_arglist_get_string(opt, OPT_OUTPATH, OPT_OUTPATH_PATH, 0, &out_path);

	printf("in path: %s\n", in_path);
	printf("out path: %s\n", out_path);

	FILE *fp = fopen(out_path, "w+b");

	struct node root;
	node_init(&root);
	fwrite(&root, sizeof root, 1, fp);

	struct data_tree tree;
	b_tree_init(&tree.base, &ops, ORDER);
	tree.fp = fp;


	for (int i = 1; i <= 32; i++) {
		int key = rand() % 65535;
		//int key = i;
		// printf("%d: adding [%d]\n", i, key);
		struct entry e = { .key = key, .value = key * 2 };
		b_tree_put(&tree.base, (b_tree_node_entry *)&e);
	}

	tree_print(&tree.base);
	
	fclose(fp);

	return 0;
}

B_COMMAND(CMD_CREATE, CMD_ROOT)
{
	B_COMMAND_NAME("create");
	B_COMMAND_SHORT_NAME('C');
	B_COMMAND_DESC("create an ec3 file");
	B_COMMAND_FLAGS(B_COMMAND_SHOW_HELP_BY_DEFAULT);
	B_COMMAND_FUNCTION(create);

	B_COMMAND_HELP_OPTION();

	B_COMMAND_OPTION(OPT_OUTPATH)
	{
		B_OPTION_SHORT_NAME('o');
		B_OPTION_LONG_NAME("out");
		B_OPTION_DESC("the path to save the new file to");

		B_OPTION_ARG(OPT_OUTPATH_PATH)
		{
			B_ARG_NAME("path");
			B_ARG_NR_VALUES(1);
		}
	}

	B_COMMAND_ARG(ARG_INPATH)
	{
		B_ARG_NAME("input file");
		B_ARG_NR_VALUES(1);
	}

	B_COMMAND_USAGE()
	{
		B_COMMAND_USAGE_ARG(ARG_INPATH);
		B_COMMAND_USAGE_OPT(OPT_OUTPATH);
	}
}