#include <dirent.h>
#include <err.h>
#include <errno.h>
#include <fcntl.h>
#include <sha1.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <unistd.h>
#include <sys/stat.h>
#include <sys/types.h>

#define REPO   ".cvn"
#define INDEX  "index"

#define MALLOC(s) _xmalloc((s), __FILE__, __LINE__)
#define REALLOC(p, s) _xrealloc((p), (s), __FILE__, __LINE__)

static inline void init(int argc, char *argv[]);
static inline void status(int argc, char *argv[]);

static inline void traverse(void);
static inline int ignore(const char *path);
static inline int cmp(const void *a, const void *b);

struct stack;
struct stack_ent;
static inline void stack_alloc(struct stack *st);
static inline struct stack_ent *pop(struct stack *st);
static inline void push(struct stack *st, struct stack_ent *new_ent);
static inline void stack_free(struct stack *st);

static inline void *_xmalloc(size_t s, const char *file, int line);
static inline void *_xrealloc(void *ptr, size_t s, const char *file, int line);

struct command {
	char *name;
	void (*func)(int argc, char *argv[]);
};

struct command cmd[] = {
	{"init", init},
	{"status", status},
	{NULL, NULL}
};

int main(int argc, char *argv[])
{
	int i;

	if (argc < 2)
		errx(1, "Usage: %s <command> [<args>]", argv[0]);
	
	for (i = 0; cmd[i].name != NULL; i++) {
		if (strcmp(argv[1], cmd[i].name) == 0) {
			cmd[i].func(argc - 1, argv + 1);
			return 0;
		}
	}

	return 0;
}

static inline void init(int argc, char *argv[])
{
	char *branch;
	int opt, repo_fd, idx_fd;

	optind = 1; 
	while ((opt = getopt(argc, argv, "b:")) != -1) {
		switch (opt) {
			case 'b': 
				branch = optarg;
				break;
			default: 
				break;
		}
	}

	if (mkdir(REPO, 0755) == -1) {
		if (errno != EEXIST)
			err(1, "Failed to create repository");
	}

	if ((repo_fd = open(REPO, O_RDONLY | O_DIRECTORY)) == -1)
		err(1, "Failed to open repository");

	if ((idx_fd = openat(repo_fd, INDEX, 
		O_WRONLY | O_CREAT | O_EXCL, 0644)) == -1) {
		if (errno != EEXIST) {
			close(repo_fd);
			err(1, "Failed to create index");
		}
	} else
		close(idx_fd);

	close(repo_fd);
	printf("Initialized repository in %s\n", REPO);
}

static inline void status(int argc, char *argv[])
{
	traverse();
}

struct stack_ent {
	char *path;
	int is_dir;
	struct stack_ent *parent;
};

struct stack {
	struct stack_ent **ents;
	size_t len;
	size_t cap;
};

static inline void traverse(void)
{
	DIR *dir;
	char *rel_path;
	struct stat st;
	struct dirent *entry;
	struct stack work_tree, stk;
	struct stack_ent *cur_dir, *root, *new_ent;

	stack_alloc(&stk);
	stack_alloc(&work_tree);
	
	root = MALLOC(sizeof(struct stack_ent));
	root->path = strdup(".");
	root->is_dir = 1;
	root->parent = NULL;
	push(&stk, root);

	while (stk.len > 0) {
		cur_dir = pop(&stk);
		if (!(dir = opendir(cur_dir->path))) {
			warn("Failed to open directory %s", cur_dir->path);
			continue;
		}

		push(&work_tree, cur_dir);

		while ((entry = readdir(dir))) {
			if (ignore(entry->d_name))
				continue;
			if (asprintf(&rel_path, "%s/%s", cur_dir->path, entry->d_name) == -1)
				err(1, "asprintf() failed");
			if (lstat(rel_path, &st) == -1) {
				warn("lstat() failed: %s", rel_path);
				free(rel_path);
				continue;
			}
			
			if (S_ISDIR(st.st_mode)) {
				new_ent = MALLOC(sizeof(struct stack_ent));
				new_ent->path = rel_path;
				new_ent->is_dir = 1;
				new_ent->parent = cur_dir;
				push(&stk, new_ent);
			} else {
				new_ent = MALLOC(sizeof(struct stack_ent));
				new_ent->path = rel_path;
				new_ent->is_dir = 0;
				new_ent->parent = cur_dir;
				push(&work_tree, new_ent);
			}
		}
		closedir(dir);
	}

	for (ssize_t i = work_tree.len - 1; i >= 0; i--) {
		printf("Entry: %s, parent: %s\n", 
		       work_tree.ents[i]->path, 
		       work_tree.ents[i]->parent ? work_tree.ents[i]->parent->path : "NONE");
	}

	stack_free(&stk);
	stack_free(&work_tree);
}

static inline void stack_alloc(struct stack *st)
{
	st->len = 0;
	st->cap = 512;
	st->ents = MALLOC(sizeof(st->ents[0]) * st->cap);
}

static inline struct stack_ent *pop(struct stack *st)
{
	return st->ents[--(st->len)];
}

static inline void push(struct stack *st, struct stack_ent *new_ent)
{
	if (st->len >= st->cap) {
		st->cap <<= 1;
		st->ents = REALLOC(st->ents, sizeof(struct stack_ent *) * st->cap);
	}
	st->ents[st->len++] = new_ent;
}

static inline void stack_free(struct stack *st)
{
	size_t i;

	for (i = 0; i < st->len; i++) {
		free(st->ents[i]->path);
		free(st->ents[i]);
	}
	free(st->ents);
}

static inline int ignore(const char *path)
{
	return strcmp(path, ".")  == 0 || 
	       strcmp(path, "..") == 0 || 
	       strcmp(path, REPO) == 0;
}

static inline void *_xmalloc(size_t s, const char *file, int line)
{
	void *p;

	if (!(p = malloc(s)))
		err(1, "%s:%d: malloc", file, line);
	return p;
}

static inline void *_xrealloc(void *ptr, size_t s, 
	const char *file, int line)
{
	void *p;

	if (!(p = realloc(ptr, s)))
		err(1, "%s:%d: realloc", file, line);
	return p;
}