/*
 * This file is free software; you can redistribute it and/or modify
 * it under the terms of the GNU General Public License, version 2,
 * as published by the Free Software Foundation.
 *
 * In addition to the permissions in the GNU General Public License,
 * the authors give you unlimited permission to link the compiled
 * version of this file into combinations with other programs,
 * and to distribute those combinations without any restriction
 * coming from the use of this file.  (The General Public License
 * restrictions do apply in other respects; for example, they cover
 * modification of the file, and distribution when not linked into
 * a combined executable.)
 *
 * This file is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; see the file COPYING.  If not, write to
 * the Free Software Foundation, 51 Franklin Street, Fifth Floor,
 * Boston, MA 02110-1301, USA.
 */
#include <stdarg.h>

#include "git2/object.h"

#include "common.h"
#include "repository.h"
#include "commit.h"
#include "tag.h"
#include "blob.h"
#include "fileops.h"

#define GIT_DIR "/.git/"
#define GIT_OBJECTS_DIR "objects/"
#define GIT_OBJECTS_INFO_DIR GIT_OBJECTS_DIR "info/"
#define GIT_OBJECTS_PACK_DIR GIT_OBJECTS_DIR "pack/"
#define GIT_REFS_DIR "refs/"
#define GIT_REFS_HEADS_DIR GIT_REFS_DIR "heads/"
#define GIT_REFS_TAGS_DIR GIT_REFS_DIR "tags/"

#define GIT_INDEX_FILE "index"
#define GIT_HEAD_FILE "HEAD"

#define GIT_SYMREF "ref: "
#define GIT_BRANCH_MASTER "master"

static const int OBJECT_TABLE_SIZE = 32;

typedef struct {
	char *path_repository;
	unsigned is_bare:1, has_been_reinit:1;
} repo_init;

/*
 * Hash table methods
 *
 * Callbacks for the ODB cache, implemented
 * as a hash table
 */
uint32_t object_table_hash(const void *key)
{
	uint32_t r;
	git_oid *id;

	id = (git_oid *)key;
	memcpy(&r, id->id, sizeof(r));
	return r;
}

int object_table_hashkey(void *object, const void *key)
{
	git_object *obj;
	git_oid *oid;

	obj = (git_object *)object;
	oid = (git_oid *)key;

	return (git_oid_cmp(oid, &obj->id) == 0);
}


/*
 * Git repository open methods
 *
 * Open a repository object from its path
 */
static int assign_repository_DIRs(git_repository *repo,
		const char *git_dir,
		const char *git_object_directory,
		const char *git_index_file,
		const char *git_work_tree)
{
	char path_aux[GIT_PATH_MAX];
	size_t path_len;

	assert(repo);

	if (git_dir == NULL || gitfo_isdir(git_dir) < GIT_SUCCESS)
		return GIT_ENOTFOUND;

	/* store GIT_DIR */
	path_len = strlen(git_dir);
	strcpy(path_aux, git_dir);

	if (path_aux[path_len - 1] != '/') {
		path_aux[path_len] = '/';
		path_aux[path_len + 1] = 0;

		path_len = path_len + 1;
	}

	repo->path_repository = git__strdup(path_aux);

	/* store GIT_OBJECT_DIRECTORY */
	if (git_object_directory == NULL)
		strcpy(path_aux + path_len, GIT_OBJECTS_DIR);
	else
		strcpy(path_aux, git_object_directory);

	if (gitfo_isdir(path_aux) < GIT_SUCCESS)
		return GIT_ENOTFOUND;

	repo->path_odb = git__strdup(path_aux);


	/* store GIT_INDEX_FILE */
	if (git_index_file == NULL)
		strcpy(path_aux + path_len, GIT_INDEX_FILE);
	else
		strcpy(path_aux, git_index_file); 

	if (gitfo_exists(path_aux) < 0)
		return GIT_ENOTFOUND;

	repo->path_index = git__strdup(path_aux);


	/* store GIT_WORK_TREE */
	if (git_work_tree == NULL)
		repo->is_bare = 1;
	else
		repo->path_workdir = git__strdup(git_work_tree);

	return GIT_SUCCESS;
}

static int guess_repository_DIRs(git_repository *repo, const char *repository_path)
{
	char path_aux[GIT_PATH_MAX], *last_DIR;
	int path_len;

	if (gitfo_isdir(repository_path) < GIT_SUCCESS)
		return GIT_ENOTAREPO;

	path_len = strlen(repository_path);
	strcpy(path_aux, repository_path);

	if (path_aux[path_len - 1] != '/') {
		path_aux[path_len] = '/';
		path_aux[path_len + 1] = 0;

		path_len = path_len + 1;
	}

	repo->path_repository = git__strdup(path_aux);

	/* objects database */
	strcpy(path_aux + path_len, GIT_OBJECTS_DIR);
	if (gitfo_isdir(path_aux) < GIT_SUCCESS)
		return GIT_ENOTAREPO;
	repo->path_odb = git__strdup(path_aux);

	/* HEAD file */
	strcpy(path_aux + path_len, GIT_HEAD_FILE);
	if (gitfo_exists(path_aux) < 0)
		return GIT_ENOTAREPO;

	path_aux[path_len] = 0;

	last_DIR = (path_aux + path_len - 2);

	while (*last_DIR != '/')
		last_DIR--;

	if (strcmp(last_DIR, GIT_DIR) == 0) {
		repo->is_bare = 0;

		/* index file */
		strcpy(path_aux + path_len, GIT_INDEX_FILE);
		repo->path_index = git__strdup(path_aux);

		/* working dir */
		*(last_DIR + 1) = 0;
		repo->path_workdir = git__strdup(path_aux);

	} else {
		repo->is_bare = 1;
		repo->path_workdir = NULL;
	}

	return GIT_SUCCESS;
}

static git_repository *repository_alloc()
{
	git_repository *repo = git__malloc(sizeof(git_repository));
	if (!repo)
		return NULL;

	memset(repo, 0x0, sizeof(git_repository));

	repo->objects = git_hashtable_alloc(
			OBJECT_TABLE_SIZE, 
			object_table_hash,
			object_table_hashkey);

	if (repo->objects == NULL) {
		free(repo);
		return NULL;
	}

	return repo;
}

int git_repository_open2(git_repository **repo_out,
		const char *git_dir,
		const char *git_object_directory,
		const char *git_index_file,
		const char *git_work_tree)
{
	git_repository *repo;
	int error = GIT_SUCCESS;

	assert(repo_out);

	repo = repository_alloc();
	if (repo == NULL)
		return GIT_ENOMEM;

	error = assign_repository_DIRs(repo, 
			git_dir, 
			git_object_directory,
			git_index_file,
			git_work_tree);

	if (error < GIT_SUCCESS)
		goto cleanup;

	error = git_odb_open(&repo->db, repo->path_odb);
	if (error < GIT_SUCCESS)
		goto cleanup;

	*repo_out = repo;
	return GIT_SUCCESS;

cleanup:
	git_repository_free(repo);
	return error;
}

int git_repository_open(git_repository **repo_out, const char *path)
{
	git_repository *repo;
	int error = GIT_SUCCESS;

	assert(repo_out && path);

	repo = repository_alloc();
	if (repo == NULL)
		return GIT_ENOMEM;

	error = guess_repository_DIRs(repo, path);
	if (error < GIT_SUCCESS)
		goto cleanup;


	error = git_odb_open(&repo->db, repo->path_odb);
	if (error < GIT_SUCCESS)
		goto cleanup;

	*repo_out = repo;
	return GIT_SUCCESS;

cleanup:
	git_repository_free(repo);
	return error;
}

void git_repository_free(git_repository *repo)
{
	git_hashtable_iterator it;
	git_object *object;

	if (repo == NULL)
		return;

	free(repo->path_workdir);
	free(repo->path_index);
	free(repo->path_repository);
	free(repo->path_odb);

	git_hashtable_iterator_init(repo->objects, &it);

	while ((object = (git_object *)
				git_hashtable_iterator_next(&it)) != NULL)
		git_object_free(object);

	git_hashtable_free(repo->objects);

	if (repo->db != NULL)
		git_odb_close(repo->db);

	if (repo->index != NULL)
		git_index_free(repo->index);

	free(repo);
}

git_index *git_repository_index(git_repository *repo)
{
	if (repo->index == NULL) {
		if (git_index_open_inrepo(&repo->index, repo) < GIT_SUCCESS)
			return NULL;

		assert(repo->index);
	}

	return repo->index;
}

git_odb *git_repository_database(git_repository *repo)
{
	assert(repo);
	return repo->db;
}

int git_repository_newobject(git_object **object_out, git_repository *repo, git_otype type)
{
	git_object *object = NULL;

	assert(object_out && repo);

	*object_out = NULL;

	switch (type) {
	case GIT_OBJ_COMMIT:
	case GIT_OBJ_TAG:
	case GIT_OBJ_TREE:
	case GIT_OBJ_BLOB:
		break;

	default:
		return GIT_EINVALIDTYPE;
	}

	object = git__malloc(git_object__size(type));

	if (object == NULL)
		return GIT_ENOMEM;

	memset(object, 0x0, git_object__size(type));
	object->repo = repo;
	object->in_memory = 1;
	object->modified = 1;

	object->source.raw.type = type;

	*object_out = object;
	return GIT_SUCCESS;
}

int git_repository_lookup(git_object **object_out, git_repository *repo, const git_oid *id, git_otype type)
{
	git_object *object = NULL;
	git_rawobj obj_file;
	int error = GIT_SUCCESS;

	assert(repo && object_out && id);

	object = git_hashtable_lookup(repo->objects, id);
	if (object != NULL) {
		*object_out = object;
		return GIT_SUCCESS;
	}

	error = git_odb_read(&obj_file, repo->db, id);
	if (error < GIT_SUCCESS)
		return error;

	if (type != GIT_OBJ_ANY && type != obj_file.type) {
		git_rawobj_close(&obj_file);
		return GIT_EINVALIDTYPE;
	}

	type = obj_file.type;

	object = git__malloc(git_object__size(type));

	if (object == NULL)
		return GIT_ENOMEM;

	memset(object, 0x0, git_object__size(type));

	/* Initialize parent object */
	git_oid_cpy(&object->id, id);
	object->repo = repo;
	memcpy(&object->source.raw, &obj_file, sizeof(git_rawobj));
	object->source.open = 1;

	switch (type) {

	case GIT_OBJ_COMMIT:
		error = git_commit__parse((git_commit *)object);
		break;

	case GIT_OBJ_TREE:
		error = git_tree__parse((git_tree *)object);
		break;

	case GIT_OBJ_TAG:
		error = git_tag__parse((git_tag *)object);
		break;

	case GIT_OBJ_BLOB:
		error = git_blob__parse((git_blob *)object);
		break;

	default:
		break;
	}

	if (error < GIT_SUCCESS) {
		git_object_free(object);
		return error;
	}

	git_object__source_close(object);
	git_hashtable_insert(repo->objects, &object->id, object);

	*object_out = object;
	return GIT_SUCCESS;
}

static int repo_init_reinit(repo_init *results)
{
	/* TODO: reinit the repository */
	results->has_been_reinit = 1;
	return GIT_SUCCESS;
}

static int repo_init_createhead(const char *head_path)
{
	git_file fd;
	int error = GIT_SUCCESS;
	char head_symlink[50];
	int len;

	len = sprintf(head_symlink, "%s %s%s\n", GIT_SYMREF, GIT_REFS_HEADS_DIR, GIT_BRANCH_MASTER);
	
	if ((fd = gitfo_creat(head_path, S_IREAD | S_IWRITE)) < GIT_SUCCESS)
		return GIT_ERROR;

	error = gitfo_write(fd, (void*)head_symlink, strlen(head_symlink));

	gitfo_close(fd);
	return error;
}

static int repo_init_structure(repo_init *results)
{
	const int mode = 0755; /* or 0777 ? */

	char temp_path[GIT_PATH_MAX];
	int path_len;
	char *git_dir = results->path_repository;

	if (gitfo_mkdir_recurs(git_dir, mode))
		return GIT_ERROR;

	path_len = strlen(git_dir);
	strcpy(temp_path, git_dir);

	/* Does HEAD file already exist ? */
	strcpy(temp_path + path_len, GIT_HEAD_FILE);

	if (gitfo_exists(temp_path) == GIT_SUCCESS)
		return repo_init_reinit(results);

	if (repo_init_createhead(temp_path) < GIT_SUCCESS)
		return GIT_ERROR;

	/* Creates the '/objects/info/' directory */
	strcpy(temp_path + path_len, GIT_OBJECTS_INFO_DIR);
	if (gitfo_mkdir_recurs(temp_path, mode))
		return GIT_ERROR;

	/* Creates the '/objects/pack/' directory */
	strcpy(temp_path + path_len, GIT_OBJECTS_PACK_DIR);
	if (gitfo_mkdir(temp_path, mode))
		return GIT_ERROR;

	/* Creates the '/refs/heads/' directory */
	strcpy(temp_path + path_len, GIT_REFS_HEADS_DIR);
	if (gitfo_mkdir_recurs(temp_path, mode))
		return GIT_ERROR;

	/* Creates the '/refs/tags/' directory */
	strcpy(temp_path + path_len, GIT_REFS_TAGS_DIR);
	if (gitfo_mkdir(temp_path, mode))
		return GIT_ERROR;

	/* TODO: what's left? templates? */

	return GIT_SUCCESS;
}

static int repo_init_find_dir(repo_init *results, const char* path)
{
	const int MAX_GITDIR_TREE_STRUCTURE_PATH_LENGTH = 66;

	char temp_path[GIT_PATH_MAX];
	int path_len;

	path_len = strlen(path);
	strcpy(temp_path, path);

	/* Ensure path has a trailing slash */
	if (temp_path[path_len - 1] != '/') {
		temp_path[path_len] = '/';
		temp_path[path_len + 1] = 0;

		path_len = path_len + 1;
	}

	if (!results->is_bare) {
		strcpy(temp_path + path_len - 1, GIT_DIR);
		path_len = path_len + strlen(GIT_DIR) - 1; /* Skip the leading slash from the constant */
	}

	if (path_len >= GIT_PATH_MAX - MAX_GITDIR_TREE_STRUCTURE_PATH_LENGTH)
		return GIT_ENOTAREPO;

	results->path_repository = git__strdup(temp_path);

	return GIT_SUCCESS;
}

int git_repository_init(git_repository **repo_out, const char *path, unsigned is_bare)
{
	int error = GIT_SUCCESS;
	repo_init results;
	
	assert(repo_out && path);

	results.path_repository = NULL;
	results.is_bare = is_bare;

	error = repo_init_find_dir(&results, path);
	if (error < GIT_SUCCESS)
		goto cleanup;

	error = repo_init_structure(&results);
	if (error < GIT_SUCCESS)
		goto cleanup;

	error = git_repository_open(repo_out, results.path_repository);

cleanup:
	free(results.path_repository);
	return error;
}