extends Node

const API_SLUG := "https://api.github.com/repos/"
const RELEASES_SLUG := "godotengine/godot/releases"
const ASSET_SLUG := "assets/%s"

const RELEASES_BASE_FOLDER := "user://releases"
const RELEASES_FILE := RELEASES_BASE_FOLDER + "/releases.json"
const TEMP_FOLDER := "user://_tmp/"

const FETCH_COOLDOWN := 60.0 # seconds

var releases: Releases
var github_token: String = OS.get_environment("GITHUB_TOKEN")

var http: HTTPRequest = HTTPRequest.new()
var is_downloading: bool = false

var threads: Array[Thread]

signal releases_fetched(releases: Releases)
signal version_downloaded(version: String)
signal export_templates_downloaded(version: String)
signal status_update(status: String)

enum Status{
	IDLE,
	RELEASE_DOWNLOAD_IN_PROGRESS,
	TEMPLATE_DOWNLOAD_IN_PROGRESS,
	DOWNLOAD_DONE,
	FETCHING_RELEASES,
	FETCHING_DONE,
	VERSION_NOT_IN_INDEX,
	RELEASE_ALREADY_EXISTS,
	TEMPLATE_ALREADY_EXISTS,
	UNPACKING_TEMPLATES,
	UNPACKING_RELEASE,
	RELEASE_INSTALLED,
	TEMPLATE_INSTALLED,
}

const STATUS_MESSAGES := {
	Status.IDLE: "Idle",
	Status.RELEASE_DOWNLOAD_IN_PROGRESS: "Downloading Godot v%s",
	Status.TEMPLATE_DOWNLOAD_IN_PROGRESS: "Downloading Export Templates for v%s",
	Status.DOWNLOAD_DONE: "Done downloading",
	Status.FETCHING_RELEASES: "Fetching releases",
	Status.FETCHING_DONE: "Done fetching releases",
	Status.VERSION_NOT_IN_INDEX: "Version not in index. Fetch first",
	Status.RELEASE_ALREADY_EXISTS: "This version already exists",
	Status.TEMPLATE_ALREADY_EXISTS: "Templates for this version already exist",
	Status.UNPACKING_TEMPLATES: "Unpacking Export Templates for v%s",
	Status.UNPACKING_RELEASE: "Unpacking Godot v%s",
	Status.RELEASE_INSTALLED: "Godot v%s installed",
	Status.TEMPLATE_INSTALLED: "Export Templates for Godot v%s installed",
}

func _ready() -> void:
	DirAccess.make_dir_absolute(TEMP_FOLDER)
	DirAccess.make_dir_absolute(RELEASES_BASE_FOLDER)
	add_child(http)
	releases = load_releases()
	clean_tmp()


func fetch_releases(force_local: bool = false) -> void:
	if force_local && FileAccess.file_exists(RELEASES_FILE):
		releases_fetched.emit(releases)
		return

	if is_downloading:
		print("Another download is in progress, try again later")
		return

	if releases.last_checked_at + FETCH_COOLDOWN > Time.get_unix_time_from_system():
		print("already fetched recently, returning local")
		releases_fetched.emit(releases)
		return

	var response_func = func(result: int, _response_code: int, _headers: PackedStringArray, body: PackedByteArray):
		if result != OK:
			return

		releases.clear()
		releases.last_checked_at = Time.get_unix_time_from_system()
		var d: Array = JSON.parse_string(body.get_string_from_ascii())
		for i in d:
			# tag name is version name
			var rm := releases.get_or_create_version_metadata(i.tag_name)

			# we already have this one
			if rm.binary_github_asset_id != -1:
				continue

			var file_name_placeholder := "Godot_v%s.zip"
			# only linux for now
			var file_name_template: String = "%s_linux.x86_64" % i.tag_name
			var file_name_template_x11: String = "%s_x11.64" % i.tag_name
			var file_name := file_name_placeholder % file_name_template
			var file_name_x11 := file_name_placeholder % file_name_template_x11

			var export_template: String = "Godot_v%s_export_templates.tpz" % i.tag_name
			# go through assets of this release and find our os
			for asset in i.assets:
				if asset.name == file_name || asset.name == file_name_x11:
					rm.binary_github_asset_id = asset.id
					rm.binary_github_filename = asset.name
				if asset.name == export_template:
					rm.export_github_asset_id = asset.id
					rm.export_github_filename = asset.name

			# if we still have an empty item, it's too old to use
			# (meaning it's not mirrored on github)
			# so we remove it
			if rm.is_empty():
				releases.releases.erase(i.tag_name)

		releases_fetched.emit(releases)
		status_update.emit(STATUS_MESSAGES[Status.FETCHING_DONE])
		is_downloading = false
		save_releases()

	var headers := [
		"Accept: application/vnd.github+json",
		"Authorization: Bearer %s" % github_token,
		"X-GitHub-Api-Version: 2022-11-28",
	]
	is_downloading = true
	status_update.emit(STATUS_MESSAGES[Status.FETCHING_RELEASES])
	http.request(API_SLUG + RELEASES_SLUG, PackedStringArray(headers))
	http.request_completed.connect(response_func, CONNECT_ONE_SHOT)


func download_release(version: String) -> void:
	if is_downloading:
		print("downloading something, try again later")
		return

	if !releases.releases.has(version):
#		print("this version is not in the index yet or does not exist. fetch first")
		status_update.emit(STATUS_MESSAGES[Status.VERSION_NOT_IN_INDEX])
		return

	if (releases.releases[version] as ReleaseMetadata).binary_path != "":
#		print("already have this version")
		status_update.emit(STATUS_MESSAGES[Status.RELEASE_ALREADY_EXISTS])
		return

	var rm: ReleaseMetadata = releases.releases[version]
	var response_func = func(_result: int, response_code: int, _headers: PackedStringArray, body: PackedByteArray, filename: String):
		if response_code == 200:
			# download happens in place.
			# we know the file is zip, so save it to temp first before unpacking
			status_update.emit(STATUS_MESSAGES[Status.DOWNLOAD_DONE])
			print("got it in place")
			print("downloading url: ", rm.binary_github_filename)
			var zip_filename := TEMP_FOLDER.path_join("%s.zip" % version)
			print("making zip: ", zip_filename)
			var f := FileAccess.open(zip_filename, FileAccess.WRITE)
			if f.get_error() != OK:
				print("zip file creation error:", f.get_error())
				return
			f.store_buffer(body)
			f.close()

			var zip := ZIPReader.new()
			var zerr := zip.open(zip_filename)
			if zerr != OK:
				print("error opening zip file: ", zerr)
				return
			var res := zip.read_file(filename.trim_suffix(".zip"))
			zip.close()
			clean_tmp()
			status_update.emit(STATUS_MESSAGES[Status.UNPACKING_RELEASE] % version)
			var d := DirAccess.open(RELEASES_BASE_FOLDER)
			d.make_dir_recursive(version)
			var new_file := RELEASES_BASE_FOLDER.path_join(version)
			new_file = new_file.path_join("godot")
			f = FileAccess.open(new_file, FileAccess.WRITE)
			f.store_buffer(res)
			f.close()
			rm.binary_path = new_file
			version_downloaded.emit(version)
			status_update.emit(STATUS_MESSAGES[Status.RELEASE_INSTALLED] % version)
			is_downloading = false
			save_releases()

		elif response_code == 302:
			# not in place
			print("tried downloading, but got a 302 which is not currently supported")

	var headers = [
		"Accept: application/octet-stream",
		"Authorization: Bearer %s" % github_token,
		"X-GitHub-Api-Version: 2022-11-28",
	]
	var asset_url = API_SLUG.path_join(RELEASES_SLUG).path_join(ASSET_SLUG) % rm.binary_github_asset_id
	status_update.emit(STATUS_MESSAGES[Status.RELEASE_DOWNLOAD_IN_PROGRESS] % version)
	is_downloading = true
	http.request(asset_url, PackedStringArray(headers))
	http.request_completed.connect(response_func.bind(rm.binary_github_filename), CONNECT_ONE_SHOT)


func download_export_templates(version: String) -> void:
	if is_downloading:
		print("downloading something, try again later")
		return

	if !releases.releases.has(version):
#		print("this version is not in the index yet or does not exist. fetch first")
		status_update.emit(STATUS_MESSAGES[Status.VERSION_NOT_IN_INDEX])
		return

	if (releases.releases[version] as ReleaseMetadata).export_templates_path != "":
#		print("already have templates for this version")
		status_update.emit(STATUS_MESSAGES[Status.TEMPLATE_ALREADY_EXISTS])
		return

	var rm: ReleaseMetadata = releases.releases[version]
	var response_func = func(_result: int, response_code: int, _headers: PackedStringArray, body: PackedByteArray):
		if response_code == 200:
			status_update.emit(STATUS_MESSAGES[Status.DOWNLOAD_DONE])
			print("got it in place")
			print("downloading url: ", rm.export_github_filename)
			var zip_filename := TEMP_FOLDER.path_join("%s_export.tpz" % version)
			print("making zip: ", zip_filename)
			var f := FileAccess.open(zip_filename, FileAccess.WRITE)
			if f.get_error() != OK:
				print("zip file creation error: ", f.get_error())
				return
			f.store_buffer(body)
			f.close()

			var zip := ZIPReader.new()
			var zerr := zip.open(zip_filename)
			if zerr != OK:
				print("error opening zip file: ", zerr)
				return
			var files := zip.get_files()
			var d := DirAccess.open(RELEASES_BASE_FOLDER)
			d.make_dir_recursive(version.path_join("templates"))
			var templates_folder := RELEASES_BASE_FOLDER.path_join(version)
			status_update.emit(STATUS_MESSAGES[Status.UNPACKING_TEMPLATES] % version)
			for file in files:
				var t := Thread.new()
				threads.append(t)
				t.start(unpack_zip_file.bind(zip_filename, file, templates_folder.path_join(file), t, version))

			zip.close()
			# don't clean tmp just yet, since there might be other threads
			# that are still unpacking from the same zip.
			# side note: why do we have to have the zip in filesystem instead
			# of memory? this would be much easier...
			rm.export_templates_path = ProjectSettings.globalize_path(templates_folder.path_join("templates"))
			export_templates_downloaded.emit(version)
			is_downloading = false
			save_releases()
		elif response_code == 302:
			# not in place
			print("tried downloading, but got a 302 which is not currently supported")

	var headers = [
		"Accept: application/octet-stream",
		"Authorization: Bearer %s" % github_token,
		"X-GitHub-Api-Version: 2022-11-28",
	]
	var asset_url = API_SLUG.path_join(RELEASES_SLUG).path_join(ASSET_SLUG) % rm.export_github_asset_id
	status_update.emit(STATUS_MESSAGES[Status.TEMPLATE_DOWNLOAD_IN_PROGRESS] % version)
	is_downloading = true
	http.request(asset_url, PackedStringArray(headers))
	http.request_completed.connect(response_func, CONNECT_ONE_SHOT)


func unpack_zip_file(zip_file: String, from_file: String, dest_file: String, thread: Thread, version: String) -> void:
	print("extracting file ", from_file, " to: ", dest_file)
	var z := ZIPReader.new()
	var f := z.open(zip_file)
	if f != OK:
		print("error opening zip file: ", zip_file, " from thread ", thread, ", exiting early.")
		_clean_threads.call_deferred(thread)
		return

	var file := FileAccess.open(dest_file, FileAccess.WRITE)
	file.store_buffer(z.read_file(from_file))
	file.close()
	z.close()

	_clean_threads.call_deferred(thread, version)


func _clean_threads(thread: Thread, version: String) -> void:
	threads.erase(thread)
	thread.wait_to_finish()

	if threads.is_empty():
		status_update.emit(STATUS_MESSAGES[Status.TEMPLATE_INSTALLED] % version)
		clean_tmp()


func save_releases() -> void:
	var f := FileAccess.open(RELEASES_FILE, FileAccess.WRITE)
	f.store_string(releases.to_json())


func load_releases() -> Releases:
	if !FileAccess.file_exists(RELEASES_FILE):
		return Releases.new()

	var f := FileAccess.open(RELEASES_FILE, FileAccess.READ)
	return Releases.from_json(f.get_as_text())


func _exit_tree() -> void:
	for t in threads:
		t.wait_to_finish()

	clean_tmp()


func get_version_metadata(version: String) -> ReleaseMetadata:
	return releases.releases.get(version)


func get_installed_versions() -> Array[ReleaseMetadata]:
	var res: Array[ReleaseMetadata] = []
	for version in releases.releases:
		if is_version_installed(version):
			res.append(releases.releases[version])
	return res


func clean_tmp() -> void:
	var d := DirAccess.open(TEMP_FOLDER)
	if !d:
		return

	var to_delete: Array[String] = []
	d.list_dir_begin()
	var file_name := d.get_next()
	while file_name != "":
		to_delete.append(file_name)
		file_name = d.get_next()
	d.list_dir_end()

	for f in to_delete:
		d.remove(f)


# helper methods
func is_version_installed(version: String) -> bool:
	return get_version_metadata(version).binary_path != ""


func is_version_templates_installed(version) -> bool:
	return get_version_metadata(version).export_templates_path != ""


class ReleaseMetadata:
	var binary_path: String
	var is_mono: bool
	var export_templates_path: String

	var binary_github_asset_id: int = -1
	var binary_github_filename: String
	var export_github_asset_id: int = -1
	var export_github_filename: String


	func is_empty() -> bool:
		return \
		binary_github_asset_id == -1 && export_github_asset_id == -1

	func to_d() -> Dictionary:
		return {
			"binary_path": binary_path,
			"is_mono": is_mono,
			"export_templates_path": export_templates_path,
			"binary_github_asset_id": binary_github_asset_id,
			"export_github_asset_id": export_github_asset_id,
			"binary_github_filename": binary_github_filename,
			"export_github_filename": export_github_filename,
		}


	static func from_d(d: Dictionary) -> ReleaseMetadata:
		var res := ReleaseMetadata.new()
		res.binary_path = d.binary_path
		res.is_mono = d.is_mono
		res.export_templates_path = d.export_templates_path
		res.binary_github_asset_id = d.binary_github_asset_id
		res.export_github_asset_id = d.export_github_asset_id
		res.binary_github_filename = d.binary_github_filename
		res.export_github_filename = d.export_github_filename
		return res


class Releases:
	# version[String]: ReleaseMetadata
	var releases: Dictionary
	var last_checked_at: float
	var os: String


	func clear() -> void:
		for r in releases.keys():
			if (releases[r] as ReleaseMetadata).binary_path == "":
				releases.erase(r)


	func get_or_create_version_metadata(version: String) -> ReleaseMetadata:
		if releases.has(version):
			return releases[version]

		var r := ReleaseMetadata.new()
		releases[version] = r
		return r


	func is_empty() -> bool:
		return releases.is_empty()


	func to_json() -> String:
		var releases_dict := {}
		for i in releases:
			releases_dict[i] = (releases[i] as ReleaseMetadata).to_d()

		var d := {
			"os": os,
			"last_checked_at": last_checked_at,
			"releases": releases_dict,
		}

		return JSON.stringify(d, "\t", false)


	static func from_json(json: String) -> Releases:
		var d: Dictionary = JSON.parse_string(json)
		var releases_dict := {}
		for i in d.releases:
			releases_dict[i] = ReleaseMetadata.from_d(d.releases[i])

		var r := Releases.new()
		r.releases = releases_dict
		r.os = d.os
		r.last_checked_at = d.last_checked_at
		return r