/*
 * Copyright (C) 2009-2012 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 "iterator.h"
#include "tree.h"
#include "ignore.h"
#include "buffer.h"

typedef struct tree_iterator_frame tree_iterator_frame;
struct tree_iterator_frame {
	tree_iterator_frame *next;
	git_tree *tree;
	unsigned int index;
};

typedef struct {
	git_iterator base;
	git_repository *repo;
	tree_iterator_frame *stack;
	git_index_entry entry;
	git_buf path;
} tree_iterator;

static const git_tree_entry *tree_iterator__tree_entry(tree_iterator *ti)
{
	return (ti->stack == NULL) ? NULL :
		git_tree_entry_byindex(ti->stack->tree, ti->stack->index);
}

static int tree_iterator__current(
	git_iterator *self, const git_index_entry **entry)
{
	int error;
	tree_iterator *ti = (tree_iterator *)self;
	const git_tree_entry *te = tree_iterator__tree_entry(ti);

	*entry = NULL;

	if (te == NULL)
		return GIT_SUCCESS;

	ti->entry.mode = te->attr;
	git_oid_cpy(&ti->entry.oid, &te->oid);
	error = git_buf_joinpath(&ti->path, ti->path.ptr, te->filename);
	if (error < GIT_SUCCESS)
		return error;
	ti->entry.path = ti->path.ptr;

	*entry = &ti->entry;

	return GIT_SUCCESS;
}

static int tree_iterator__at_end(git_iterator *self)
{
	return (tree_iterator__tree_entry((tree_iterator *)self) == NULL);
}

static tree_iterator_frame *tree_iterator__alloc_frame(git_tree *tree)
{
	tree_iterator_frame *tf = git__calloc(1, sizeof(tree_iterator_frame));
	tf->tree = tree;
	return tf;
}

static int tree_iterator__expand_tree(tree_iterator *ti)
{
	int error;
	git_tree *subtree;
	const git_tree_entry *te = tree_iterator__tree_entry(ti);
	tree_iterator_frame *tf;

	while (te != NULL && entry_is_tree(te)) {
		error = git_tree_lookup(&subtree, ti->repo, &te->oid);
		if (error != GIT_SUCCESS)
			return error;

		if ((tf = tree_iterator__alloc_frame(subtree)) == NULL)
			return GIT_ENOMEM;

		tf->next  = ti->stack;
		ti->stack = tf;

		error = git_buf_joinpath(&ti->path, ti->path.ptr, te->filename);
		if (error < GIT_SUCCESS)
			return error;

		te = tree_iterator__tree_entry(ti);
	}

	return GIT_SUCCESS;
}

static void tree_iterator__pop_frame(tree_iterator *ti)
{
	tree_iterator_frame *tf = ti->stack;
	ti->stack = tf->next;
	if (ti->stack != NULL) /* don't free the initial tree */
		git_tree_free(tf->tree);
	git__free(tf);
}

static int tree_iterator__advance(
	git_iterator *self, const git_index_entry **entry)
{
	int error = GIT_SUCCESS;
	tree_iterator *ti = (tree_iterator *)self;
	const git_tree_entry *te = NULL;

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

	while (ti->stack != NULL) {
		/* remove old entry filename */
		git_buf_rtruncate_at_char(&ti->path, '/');

		te = git_tree_entry_byindex(ti->stack->tree, ++ti->stack->index);
		if (te != NULL)
			break;

		tree_iterator__pop_frame(ti);
		git_buf_rtruncate_at_char(&ti->path, '/');
	}

	if (te && entry_is_tree(te))
		error = tree_iterator__expand_tree(ti);

	if (error == GIT_SUCCESS && entry != NULL)
		error = tree_iterator__current(self, entry);

	return error;
}

static void tree_iterator__free(git_iterator *self)
{
	tree_iterator *ti = (tree_iterator *)self;
	while (ti->stack != NULL)
		tree_iterator__pop_frame(ti);
	git_buf_free(&ti->path);
}

int git_iterator_for_tree(
	git_repository *repo, git_tree *tree, git_iterator **iter)
{
	int error;
	tree_iterator *ti = git__calloc(1, sizeof(tree_iterator));
	if (!ti)
		return GIT_ENOMEM;

	ti->base.type    = GIT_ITERATOR_TREE;
	ti->base.current = tree_iterator__current;
	ti->base.at_end  = tree_iterator__at_end;
	ti->base.advance = tree_iterator__advance;
	ti->base.free    = tree_iterator__free;
	ti->repo         = repo;
	ti->stack        = tree_iterator__alloc_frame(tree);

	if ((error = tree_iterator__expand_tree(ti)) < GIT_SUCCESS)
		git_iterator_free((git_iterator *)ti);
	else
		*iter = (git_iterator *)ti;

	return error;
}


typedef struct {
	git_iterator base;
	git_index *index;
	unsigned int current;
} index_iterator;

static int index_iterator__current(
	git_iterator *self, const git_index_entry **entry)
{
	index_iterator *ii = (index_iterator *)self;
	*entry = git_index_get(ii->index, ii->current);
	return GIT_SUCCESS;
}

static int index_iterator__at_end(git_iterator *self)
{
	index_iterator *ii = (index_iterator *)self;
	return (ii->current >= git_index_entrycount(ii->index));
}

static int index_iterator__advance(
	git_iterator *self, const git_index_entry **entry)
{
	index_iterator *ii = (index_iterator *)self;
	if (ii->current < git_index_entrycount(ii->index))
		ii->current++;
	if (entry)
		*entry = git_index_get(ii->index, ii->current);
	return GIT_SUCCESS;
}

static void index_iterator__free(git_iterator *self)
{
	index_iterator *ii = (index_iterator *)self;
	git_index_free(ii->index);
	ii->index = NULL;
}

int git_iterator_for_index(git_repository *repo, git_iterator **iter)
{
	int error;
	index_iterator *ii = git__calloc(1, sizeof(index_iterator));
	if (!ii)
		return GIT_ENOMEM;

	ii->base.type    = GIT_ITERATOR_INDEX;
	ii->base.current = index_iterator__current;
	ii->base.at_end  = index_iterator__at_end;
	ii->base.advance = index_iterator__advance;
	ii->base.free    = index_iterator__free;
	ii->current      = 0;

	if ((error = git_repository_index(&ii->index, repo)) < GIT_SUCCESS)
		git__free(ii);
	else
		*iter = (git_iterator *)ii;
	return error;
}


typedef struct workdir_iterator_frame workdir_iterator_frame;
struct workdir_iterator_frame {
	workdir_iterator_frame *next;
	git_vector entries;
	unsigned int index;
};

typedef struct {
	git_iterator base;
	git_repository *repo;
	size_t root_len;
	workdir_iterator_frame *stack;
	git_ignores ignores;
	git_index_entry entry;
	git_buf path;
	int is_ignored;
} workdir_iterator;

static workdir_iterator_frame *workdir_iterator__alloc_frame(void)
{
	workdir_iterator_frame *wf = git__calloc(1, sizeof(workdir_iterator_frame));
	if (wf == NULL)
		return wf;
	if (git_vector_init(&wf->entries, 0, git__strcmp_cb) != GIT_SUCCESS) {
		git__free(wf);
		return NULL;
	}
	return wf;
}

static void workdir_iterator__free_frame(workdir_iterator_frame *wf)
{
	unsigned int i;
	char *path;

	git_vector_foreach(&wf->entries, i, path)
		git__free(path);
	git_vector_free(&wf->entries);
	git__free(wf);
}

static int workdir_iterator__update_entry(workdir_iterator *wi);

static int workdir_iterator__expand_dir(workdir_iterator *wi)
{
	int error;
	workdir_iterator_frame *wf = workdir_iterator__alloc_frame();
	if (wf == NULL)
		return GIT_ENOMEM;

	/* allocate dir entries with extra byte (the "1" param) so we
	 * can suffix directory names with a "/".
	 */
	error = git_path_dirload(wi->path.ptr, wi->root_len, 1, &wf->entries);
	if (error < GIT_SUCCESS || wf->entries.length == 0) {
		workdir_iterator__free_frame(wf);
		return GIT_ENOTFOUND;
	}

	git_vector_sort(&wf->entries);
	wf->next  = wi->stack;
	wi->stack = wf;

	/* only push new ignores if this is not top level directory */
	if (wi->stack->next != NULL) {
		int slash_pos = git_buf_rfind_next(&wi->path, '/');
		(void)git_ignore__push_dir(&wi->ignores, &wi->path.ptr[slash_pos + 1]);
	}

	return workdir_iterator__update_entry(wi);
}

static int workdir_iterator__current(
	git_iterator *self, const git_index_entry **entry)
{
	workdir_iterator *wi = (workdir_iterator *)self;
	*entry = (wi->entry.path == NULL) ? NULL : &wi->entry;
	return GIT_SUCCESS;
}

static int workdir_iterator__at_end(git_iterator *self)
{
	return (((workdir_iterator *)self)->entry.path == NULL);
}

static int workdir_iterator__advance(
	git_iterator *self, const git_index_entry **entry)
{
	int error;
	workdir_iterator *wi = (workdir_iterator *)self;
	workdir_iterator_frame *wf;
	const char *next;

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

	if (wi->entry.path == NULL)
		return GIT_SUCCESS;

	while ((wf = wi->stack) != NULL) {
		next = git_vector_get(&wf->entries, ++wf->index);
		if (next != NULL) {
			if (strcmp(next, DOT_GIT) == 0)
				continue;
			/* else found a good entry */
			break;
		}

		/* pop workdir directory stack */
		wi->stack = wf->next;
		workdir_iterator__free_frame(wf);
		git_ignore__pop_dir(&wi->ignores);

		if (wi->stack == NULL) {
			memset(&wi->entry, 0, sizeof(wi->entry));
			return GIT_SUCCESS;
		}
	}

	error = workdir_iterator__update_entry(wi);

	if (error == GIT_SUCCESS && entry != NULL)
		error = workdir_iterator__current(self, entry);

	return error;
}

static void workdir_iterator__free(git_iterator *self)
{
	workdir_iterator *wi = (workdir_iterator *)self;

	while (wi->stack != NULL) {
		workdir_iterator_frame *wf = wi->stack;
		wi->stack = wf->next;
		workdir_iterator__free_frame(wf);
	}

	git_ignore__free(&wi->ignores);
	git_buf_free(&wi->path);
}

static int workdir_iterator__update_entry(workdir_iterator *wi)
{
	int error;
	struct stat st;
	char *relpath = git_vector_get(&wi->stack->entries, wi->stack->index);

	error = git_buf_joinpath(
		&wi->path, git_repository_workdir(wi->repo), relpath);
	if (error < GIT_SUCCESS)
		return error;

	memset(&wi->entry, 0, sizeof(wi->entry));
	wi->entry.path = relpath;

	/* skip over .git directory */
	if (strcmp(relpath, DOT_GIT) == 0)
		return workdir_iterator__advance((git_iterator *)wi, NULL);

	/* if there is an error processing the entry, treat as ignored */
	wi->is_ignored = 1;

	if (p_lstat(wi->path.ptr, &st) < 0)
		return GIT_SUCCESS;

	/* TODO: remove shared code for struct stat conversion with index.c */
	wi->entry.ctime.seconds = (git_time_t)st.st_ctime;
	wi->entry.mtime.seconds = (git_time_t)st.st_mtime;
	wi->entry.dev  = st.st_rdev;
	wi->entry.ino  = st.st_ino;
	wi->entry.mode = git_futils_canonical_mode(st.st_mode);
	wi->entry.uid  = st.st_uid;
	wi->entry.gid  = st.st_gid;
	wi->entry.file_size = st.st_size;

	/* if this is a file type we don't handle, treat as ignored */
	if (st.st_mode == 0)
		return GIT_SUCCESS;

	/* okay, we are far enough along to look up real ignore rule */
	error = git_ignore__lookup(&wi->ignores, wi->entry.path, &wi->is_ignored);
	if (error != GIT_SUCCESS)
		return GIT_SUCCESS;

	if (S_ISDIR(st.st_mode)) {
		if (git_path_contains(&wi->path, DOT_GIT) == GIT_SUCCESS) {
			/* create submodule entry */
			wi->entry.mode = S_IFGITLINK;
		} else {
			/* create directory entry that can be advanced into as needed */
			size_t pathlen = strlen(wi->entry.path);
			wi->entry.path[pathlen] = '/';
			wi->entry.path[pathlen + 1] = '\0';
			wi->entry.mode = S_IFDIR;
		}
	}

	return GIT_SUCCESS;
}

int git_iterator_for_workdir(git_repository *repo, git_iterator **iter)
{
	int error;
	workdir_iterator *wi = git__calloc(1, sizeof(workdir_iterator));
	if (!wi)
		return GIT_ENOMEM;

	wi->base.type    = GIT_ITERATOR_WORKDIR;
	wi->base.current = workdir_iterator__current;
	wi->base.at_end  = workdir_iterator__at_end;
	wi->base.advance = workdir_iterator__advance;
	wi->base.free    = workdir_iterator__free;
	wi->repo         = repo;

	error = git_buf_sets(&wi->path, git_repository_workdir(repo));
	if (error == GIT_SUCCESS)
		error = git_ignore__for_path(repo, "", &wi->ignores);
	if (error != GIT_SUCCESS) {
		git__free(wi);
		return error;
	}

	wi->root_len = wi->path.size;

	if ((error = workdir_iterator__expand_dir(wi)) < GIT_SUCCESS)
		git_iterator_free((git_iterator *)wi);
	else
		*iter = (git_iterator *)wi;

	return error;
}


int git_iterator_current_tree_entry(
	git_iterator *iter, const git_tree_entry **tree_entry)
{
	*tree_entry = (iter->type != GIT_ITERATOR_TREE) ? NULL :
		tree_iterator__tree_entry((tree_iterator *)iter);
	return GIT_SUCCESS;
}

int git_iterator_current_is_ignored(git_iterator *iter)
{
	return (iter->type != GIT_ITERATOR_WORKDIR) ? 0 :
		((workdir_iterator *)iter)->is_ignored;
}

int git_iterator_advance_into_directory(
	git_iterator *iter, const git_index_entry **entry)
{
	workdir_iterator *wi = (workdir_iterator *)iter;

	if (iter->type == GIT_ITERATOR_WORKDIR &&
		wi->entry.path && S_ISDIR(wi->entry.mode))
	{
		if (workdir_iterator__expand_dir(wi) < GIT_SUCCESS)
			/* if error loading or if empty, skip the directory. */
			return workdir_iterator__advance(iter, entry);
	}

	return entry ? git_iterator_current(iter, entry) : GIT_SUCCESS;
}