###
### file system utility
###
extends Object

class_name GDBFsUtil

const __META_FILENAME_REGEX = "__gdb_fsutil_filename_regex__"
const __META_ENVVAR_REGEX = "__gdb_fsutil_envvar_regex__"

class SpecialFolder:
	var path := ""
	var name := ""
	
	func _init(path_ : String, name_ : String):
		self.path = path_
		self.name = name_

################
# public stuff #
################
func _init() -> void:
	assert(0, "This class should not be instantiated.")

static func find_all_by_name(path : String, name : String, files_only = true) -> Dictionary:
	var result = []
	__find_all_by_name(path, name, result, files_only)
	return result

static func escape_filename(filename : String) -> String:
	return __get_filename_regex().sub(filename, "_", true)

static func is_filename_valid(filename : String) -> bool:
	return __get_filename_regex().search(filename) == null

static func load_image_resource(filename : String):
	var res = load(filename)
	if res:
		return res
	var img = Image.new()
	if img.load(filename) == OK:
		var tex = ImageTexture.new()
		tex.create_from_image(img)
		return tex
	return null

#! Retrieve information about the current git branch.
#!
#! Used to display this information in development builds.
#! Returns a dictionary with the following keys:
#!   - "branch" - the name of the current branch
#!   - "commit" - the full hash of the latest commit
#!   - "commit_short" - the shortened hash of the last commit
static func get_git_info() -> Dictionary:
	var file = File.new()
	if file.open("res://.git/HEAD", File.READ) != OK:
		return {"branch": "<unknown>", "commit": "???", "commit_short": "???"}
	var text = file.get_line()
	if !text.begins_with("ref:"):
		return {"branch": "<detached>", "commit": text, "commit_short": text.left(7)}
	var ref = text.right(5).get_file()
	file.close()
	if file.open("res://.git/refs/heads/%s" % ref, File.READ) != OK:
		return {"branch": ref, "commit": "<unknown>", "commit_short": "<unknown>"}
	var commitid = file.get_line()
	return {"branch": ref, "commit": commitid, "commit_short": commitid.left(7)}


static func get_home_folder() -> String:
	if OS.has_feature("X11"):
		if OS.has_environment("HOME"):
			return OS.get_environment("HOME")
	elif OS.has_feature("Windows"):
		if OS.has_environment("USERPROFILE"):
			return OS.get_environment("USERPROFILE")
	
	return "/"

static func get_special_folders() -> Array:
	if OS.has_feature("X11"):
		return __get_xdg_folders()
	return []

static func replace_environment_variables(string : String) -> String:
	var matches := __get_envvar_regex().search_all(string)
	var parts := PoolStringArray()
	var pos := 0
	for the_match in matches:
		var var_name : String = the_match.strings[-2] if !the_match.strings[-1] else the_match.strings[-1]
		parts.append(string.substr(pos, the_match.get_start()))
		parts.append(OS.get_environment(var_name))
		pos = the_match.get_end()
	parts.append(string.substr(pos))
	return parts.join("")

#################
# private stuff #
#################
static func __get_filename_regex() -> RegEx:
	var tree := GDBUtility.get_scene_tree()
	if tree.has_meta(__META_FILENAME_REGEX):
		return tree.get_meta(__META_FILENAME_REGEX) as RegEx
	var filename_regex := RegEx.new()
	filename_regex.compile("[^a-zA-Z0-9_\\-\\. ]")
	tree.set_meta(__META_FILENAME_REGEX, filename_regex)
	return filename_regex

static func __get_envvar_regex() -> RegEx:
	var tree := GDBUtility.get_scene_tree()
	if tree.has_meta(__META_ENVVAR_REGEX):
		return tree.get_meta(__META_ENVVAR_REGEX) as RegEx
	var envvar_regex := RegEx.new()
	if OS.has_feature("Windows"):
		envvar_regex.compile("%(\\w+)%")
	else:
		envvar_regex.compile("\\$({(\\w+)}|(\\w+))")
	
	tree.set_meta(__META_ENVVAR_REGEX, envvar_regex)
	return envvar_regex

static func __find_all_by_name(path, name, result, files_only):
	var dir = Directory.new()
	if dir.open(path) != OK:
#		print("cannot open dir %s" % path)
		return
	dir.list_dir_begin(true)
	while true:
		var fname = dir.get_next()
		if fname == "":
			break
		var full_name = path + "/" + fname
		if fname == name && (!files_only || dir.file_exists(full_name)):
			result.append(full_name)
			
		# dir_exists doesnt work for res:// paths, just attempt to add, will silently fail for files
		if true: # dir.dir_exists(full_name):
			__find_all_by_name(full_name, name, result, files_only)
	
	dir.list_dir_end()

static func __get_xdg_folders() -> Array:
	var user_dirs_filename := get_home_folder().plus_file(".config/user-dirs.dirs")
	var user_dirs_file := File.new()
	if !user_dirs_file.file_exists(user_dirs_filename):
		return []
	var status := user_dirs_file.open(user_dirs_filename, File.READ)
	if status != OK:
		printerr("Error fetching XDG user dirs.")
		return []
	
	var dir_regex := RegEx.new()
	status = dir_regex.compile("^XDG_([A-Z]+)_DIR=\"([^\"]+)\"$")
	assert(status == OK)
	
	var folders := []
	while !user_dirs_file.eof_reached():
		var line := user_dirs_file.get_line().strip_edges()
		var result := dir_regex.search(line)
		if result == null:
			continue
		var folder_name : String = result.strings[1].capitalize()
		var folder_path : String = replace_environment_variables(result.strings[2])
		folders.append(SpecialFolder.new(folder_path, folder_name))
		
	return folders