/*
 * Copyright (C) 2009-2011 the libgit2 contributors
 *
 * This file is part of libgit2, distributed under the GNU GPL v2 with
 * a Linking Exception. For full terms see the included COPYING file.
 */

#include "common.h"
#include "commit.h"
#include "tree.h"
#include "git2/repository.h"
#include "git2/object.h"

#define DEFAULT_TREE_SIZE 16
#define MAX_FILEMODE 0777777
#define MAX_FILEMODE_BYTES 6

static int valid_attributes(const int attributes) {
	return attributes >= 0 && attributes <= MAX_FILEMODE;
}

struct tree_key_search {
	const char *filename;
	size_t filename_len;
};

static int entry_search_cmp(const void *key, const void *array_member)
{
	const struct tree_key_search *ksearch = key;
	const git_tree_entry *entry = array_member;

	int result =
		git_futils_cmp_path(
			ksearch->filename, ksearch->filename_len, entry->attr & 040000,
			entry->filename, entry->filename_len, entry->attr & 040000);

	return result ? result : ((int)ksearch->filename_len - (int)entry->filename_len);
}

static int entry_sort_cmp(const void *a, const void *b)
{
	const git_tree_entry *entry_a = (const git_tree_entry *)(a);
	const git_tree_entry *entry_b = (const git_tree_entry *)(b);

	return git_futils_cmp_path(
		entry_a->filename, entry_a->filename_len, entry_a->attr & 040000,
		entry_b->filename, entry_b->filename_len, entry_b->attr & 040000);
}

static int build_ksearch(struct tree_key_search *ksearch, const char *path)
{
	size_t len = strlen(path);

	if (len && path[len - 1] == '/')
		len--;

	if (len == 0 || memchr(path, '/', len) != NULL)
		return GIT_ERROR;

	ksearch->filename = path;
	ksearch->filename_len = len;

	return GIT_SUCCESS;
}

void git_tree__free(git_tree *tree)
{
	unsigned int i;

	for (i = 0; i < tree->entries.length; ++i) {
		git_tree_entry *e;
		e = git_vector_get(&tree->entries, i);

		free(e->filename);
		free(e);
	}

	git_vector_free(&tree->entries);
	free(tree);
}

const git_oid *git_tree_id(git_tree *c)
{
	return git_object_id((git_object *)c);
}

unsigned int git_tree_entry_attributes(const git_tree_entry *entry)
{
	return entry->attr;
}

const char *git_tree_entry_name(const git_tree_entry *entry)
{
	assert(entry);
	return entry->filename;
}

const git_oid *git_tree_entry_id(const git_tree_entry *entry)
{
	assert(entry);
	return &entry->oid;
}

git_otype git_tree_entry_type(const git_tree_entry *entry)
{
	assert(entry);

	if (S_ISGITLINK(entry->attr))
		return GIT_OBJ_COMMIT;
	else if (S_ISDIR(entry->attr))
		return GIT_OBJ_TREE;
	else
		return GIT_OBJ_BLOB;
}

int git_tree_entry_2object(git_object **object_out, git_repository *repo, const git_tree_entry *entry)
{
	assert(entry && object_out);
	return git_object_lookup(object_out, repo, &entry->oid, GIT_OBJ_ANY);
}

const git_tree_entry *git_tree_entry_byname(git_tree *tree, const char *filename)
{
	int idx;
	struct tree_key_search ksearch;

	assert(tree && filename);

	if (build_ksearch(&ksearch, filename) < GIT_SUCCESS)
		return NULL;

	idx = git_vector_bsearch2(&tree->entries, entry_search_cmp, &ksearch);
	if (idx == GIT_ENOTFOUND)
		return NULL;

	return git_vector_get(&tree->entries, idx);
}

const git_tree_entry *git_tree_entry_byindex(git_tree *tree, unsigned int idx)
{
	assert(tree);
	return git_vector_get(&tree->entries, idx);
}

unsigned int git_tree_entrycount(git_tree *tree)
{
	assert(tree);
	return tree->entries.length;
}

static int tree_parse_buffer(git_tree *tree, const char *buffer, const char *buffer_end)
{
	int error = GIT_SUCCESS;

	if (git_vector_init(&tree->entries, DEFAULT_TREE_SIZE, entry_sort_cmp) < GIT_SUCCESS)
		return GIT_ENOMEM;

	while (buffer < buffer_end) {
		git_tree_entry *entry;
		long tmp;

		entry = git__calloc(1, sizeof(git_tree_entry));
		if (entry == NULL) {
			error = GIT_ENOMEM;
			break;
		}

		if (git_vector_insert(&tree->entries, entry) < GIT_SUCCESS)
			return GIT_ENOMEM;

		if (git__strtol32(&tmp, buffer, &buffer, 8) < GIT_SUCCESS ||
			!buffer || tmp > UINT_MAX || tmp < 0)
			return git__throw(GIT_EOBJCORRUPTED, "Failed to parse tree. Can't parse attributes");
		entry->attr = tmp;

		if (*buffer++ != ' ') {
			error = git__throw(GIT_EOBJCORRUPTED, "Failed to parse tree. Object it corrupted");
			break;
		}

		if (memchr(buffer, 0, buffer_end - buffer) == NULL) {
			error = git__throw(GIT_EOBJCORRUPTED, "Failed to parse tree. Object it corrupted");
			break;
		}

		entry->filename = git__strdup(buffer);
		entry->filename_len = strlen(buffer);

		while (buffer < buffer_end && *buffer != 0)
			buffer++;

		buffer++;

		git_oid_fromraw(&entry->oid, (const unsigned char *)buffer);
		buffer += GIT_OID_RAWSZ;
	}

	return error == GIT_SUCCESS ? GIT_SUCCESS : git__rethrow(error, "Failed to parse buffer");
}

int git_tree__parse(git_tree *tree, git_odb_object *obj)
{
	assert(tree);
	return tree_parse_buffer(tree, (char *)obj->raw.data, (char *)obj->raw.data + obj->raw.len);
}

static int write_tree(git_oid *oid, git_index *index, const char *dirname, unsigned int start)
{
	git_treebuilder *bld = NULL;
	unsigned int i, entries = git_index_entrycount(index);
	int error;
	size_t dirname_len = strlen(dirname);

	error = git_treebuilder_create(&bld, NULL);
	if (bld == NULL) {
		return GIT_ENOMEM;
	}

	/*
	 * This loop is unfortunate, but necessary. The index doesn't have
	 * any directores, so we need to handle that manually, and we
	 * need to keep track of the current position.
	 */
	for (i = start; i < entries; ++i) {
		git_index_entry *entry = git_index_get(index, i);
		char *filename, *next_slash;

	/*
	 * If we've left our (sub)tree, exit the loop and return. The
	 * first check is an early out (and security for the
	 * third). The second check is a simple prefix comparison. The
	 * third check catches situations where there is a directory
	 * win32/sys and a file win32mmap.c. Without it, the following
	 * code believes there is a file win32/mmap.c
	 */
		if (strlen(entry->path) < dirname_len ||
		    memcmp(entry->path, dirname, dirname_len) ||
		    (dirname_len > 0 && entry->path[dirname_len] != '/')) {
			break;
		}

		filename = entry->path + dirname_len;
		if (*filename == '/')
			filename++;
		next_slash = strchr(filename, '/');
		if (next_slash) {
			git_oid sub_oid;
			int written;
			char *subdir, *last_comp;

			subdir = git__strndup(entry->path, next_slash - entry->path);
			if (subdir == NULL) {
				error = GIT_ENOMEM;
				goto cleanup;
			}

			/* Write out the subtree */
			written = write_tree(&sub_oid, index, subdir, i);
			if (written < 0) {
				error = git__rethrow(written, "Failed to write subtree %s", subdir);
			} else {
				i = written - 1; /* -1 because of the loop increment */
			}

			/*
			 * We need to figure out what we want toinsert
			 * into this tree. If we're traversing
			 * deps/zlib/, then we only want to write
			 * 'zlib' into the tree.
			 */
			last_comp = strrchr(subdir, '/');
			if (last_comp) {
				last_comp++; /* Get rid of the '/' */
			} else {
				last_comp = subdir;
			}
			error = git_treebuilder_insert(NULL, bld, last_comp, &sub_oid, S_IFDIR);
			free(subdir);
			if (error < GIT_SUCCESS) {
				error = git__rethrow(error, "Failed to insert dir");
				goto cleanup;
			}
		} else {
			error = git_treebuilder_insert(NULL, bld, filename, &entry->oid, entry->mode);
			if (error < GIT_SUCCESS) {
				error = git__rethrow(error, "Failed to insert file");
			}
		}
	}

	error = git_treebuilder_write(oid, index->repository, bld);
	if (error < GIT_SUCCESS)
		error = git__rethrow(error, "Failed to write tree to db");

 cleanup:
	git_treebuilder_free(bld);

	if (error < GIT_SUCCESS)
		return error;
	else
		return i;
}

int git_tree_create_fromindex(git_oid *oid, git_index *index)
{
	int error;

	if (index->repository == NULL)
		return git__throw(GIT_EBAREINDEX, "Failed to create tree. The index file is not backed up by an existing repository");

	/* The tree cache didn't help us */
	error = write_tree(oid, index, "", 0);
	return (error < GIT_SUCCESS) ? git__rethrow(error, "Failed to create tree") : GIT_SUCCESS;
}

static void sort_entries(git_treebuilder *bld)
{
	git_vector_sort(&bld->entries);
}

int git_treebuilder_create(git_treebuilder **builder_p, const git_tree *source)
{
	git_treebuilder *bld;
	unsigned int i, source_entries = DEFAULT_TREE_SIZE;

	assert(builder_p);

	bld = git__calloc(1, sizeof(git_treebuilder));
	if (bld == NULL)
		return GIT_ENOMEM;

	if (source != NULL)
		source_entries = source->entries.length;

	if (git_vector_init(&bld->entries, source_entries, entry_sort_cmp) < GIT_SUCCESS) {
		free(bld);
		return GIT_ENOMEM;
	}

	if (source != NULL) {
		bld->entry_count = source_entries;
		for (i = 0; i < source->entries.length; ++i) {
			git_tree_entry *entry_src = source->entries.contents[i];
			git_tree_entry *entry = git__calloc(1, sizeof(git_tree_entry));

			if (entry == NULL) {
				git_treebuilder_free(bld);
				return GIT_ENOMEM;
			}

			entry->filename = git__strdup(entry_src->filename);

			if (entry->filename == NULL) {
				free(entry);
				git_treebuilder_free(bld);
				return GIT_ENOMEM;
			}

			entry->filename_len = entry_src->filename_len;
			git_oid_cpy(&entry->oid, &entry_src->oid);
			entry->attr = entry_src->attr;

			git_vector_insert(&bld->entries, entry);
		}
	}

	*builder_p = bld;
	return GIT_SUCCESS;
}

int git_treebuilder_insert(git_tree_entry **entry_out, git_treebuilder *bld, const char *filename, const git_oid *id, unsigned int attributes)
{
	git_tree_entry *entry;
	int pos;
	struct tree_key_search ksearch;

	assert(bld && id && filename);

	if (!valid_attributes(attributes))
		return git__throw(GIT_ERROR, "Failed to insert entry. Invalid attributes");

	if (build_ksearch(&ksearch, filename) < GIT_SUCCESS)
		return git__throw(GIT_ERROR, "Failed to insert entry. Invalid filename '%s'", filename);

	if ((pos = git_vector_bsearch2(&bld->entries, entry_search_cmp, &ksearch)) != GIT_ENOTFOUND) {
		entry = git_vector_get(&bld->entries, pos);
		if (entry->removed) {
			entry->removed = 0;
			bld->entry_count++;
		}
	} else {
		if ((entry = git__malloc(sizeof(git_tree_entry))) == NULL)
			return GIT_ENOMEM;

		memset(entry, 0x0, sizeof(git_tree_entry));
		entry->filename = git__strdup(filename);
		entry->filename_len = strlen(entry->filename);

		bld->entry_count++;
	}

	git_oid_cpy(&entry->oid, id);
	entry->attr = attributes;

	if (pos == GIT_ENOTFOUND) {
		if (git_vector_insert(&bld->entries, entry) < 0)
			return GIT_ENOMEM;
	}

	if (entry_out != NULL)
		*entry_out = entry;

	return GIT_SUCCESS;
}

static git_tree_entry *treebuilder_get(git_treebuilder *bld, const char *filename)
{
	int idx;
	git_tree_entry *entry;
	struct tree_key_search ksearch;

	assert(bld && filename);

	if (build_ksearch(&ksearch, filename) < GIT_SUCCESS)
		return NULL;

	idx = git_vector_bsearch2(&bld->entries, entry_search_cmp, &ksearch);
	if (idx == GIT_ENOTFOUND)
		return NULL;

	entry = git_vector_get(&bld->entries, idx);
	if (entry->removed)
		return NULL;

	return entry;
}

const git_tree_entry *git_treebuilder_get(git_treebuilder *bld, const char *filename)
{
	return treebuilder_get(bld, filename);
}

int git_treebuilder_remove(git_treebuilder *bld, const char *filename)
{
	git_tree_entry *remove_ptr = treebuilder_get(bld, filename);

	if (remove_ptr == NULL || remove_ptr->removed)
		return git__throw(GIT_ENOTFOUND, "Failed to remove entry. File isn't in the tree");

	remove_ptr->removed = 1;
	bld->entry_count--;
	return GIT_SUCCESS;
}

int git_treebuilder_write(git_oid *oid, git_repository *repo, git_treebuilder *bld)
{
	unsigned int i;
	int error;
	git_buf tree = GIT_BUF_INIT;

	assert(bld);

	sort_entries(bld);

	/* Grow the buffer beforehand to an estimated size */
	git_buf_grow(&tree, bld->entries.length * 72);

	for (i = 0; i < bld->entries.length; ++i) {
		git_tree_entry *entry = bld->entries.contents[i];

		if (entry->removed)
			continue;

		git_buf_printf(&tree, "%o ", entry->attr);
		git_buf_put(&tree, entry->filename, entry->filename_len + 1);
		git_buf_put(&tree, (char *)entry->oid.id, GIT_OID_RAWSZ);
	}

	if (git_buf_oom(&tree)) {
		git_buf_free(&tree);
		return git__throw(GIT_ENOMEM, "Not enough memory to build the tree data");
	}

	error = git_odb_write(oid, git_repository_database(repo), tree.ptr, tree.size, GIT_OBJ_TREE);
	git_buf_free(&tree);

	return error == GIT_SUCCESS ? GIT_SUCCESS : git__rethrow(error, "Failed to write tree");
}

void git_treebuilder_filter(git_treebuilder *bld, int (*filter)(const git_tree_entry *, void *), void *payload)
{
	unsigned int i;

	assert(bld && filter);

	for (i = 0; i < bld->entries.length; ++i) {
		git_tree_entry *entry = bld->entries.contents[i];
		if (!entry->removed && filter(entry, payload))
			entry->removed = 1;
	}
}

void git_treebuilder_clear(git_treebuilder *bld)
{
	unsigned int i;
	assert(bld);

	for (i = 0; i < bld->entries.length; ++i) {
		git_tree_entry *e = bld->entries.contents[i];
		free(e->filename);
		free(e);
	}

	git_vector_clear(&bld->entries);
}

void git_treebuilder_free(git_treebuilder *bld)
{
	git_treebuilder_clear(bld);
	git_vector_free(&bld->entries);
	free(bld);
}