--Minetest
--Copyright (C) 2018-24 rubenwardy
--
--This program is free software; you can redistribute it and/or modify
--it under the terms of the GNU Lesser General Public License as published by
--the Free Software Foundation; either version 2.1 of the License, or
--(at your option) any later version.
--
--This program 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 Lesser General Public License for more details.
--
--You should have received a copy of the GNU Lesser General Public License along
--with this program; if not, write to the Free Software Foundation, Inc.,
--51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.

if not core.get_http_api then
	return
end


contentdb = {
	loading = false,
	load_ok = false,
	load_error = false,

	-- Unordered preserves the original order of the ContentDB API,
	-- before the package list is ordered based on installed state.
	packages = {},
	packages_full = {},
	packages_full_unordered = {},
	package_by_id = {},
	aliases = {},

	number_downloading = 0,
	download_queue = {},

	REASON_NEW = "new",
	REASON_UPDATE = "update",
	REASON_DEPENDENCY = "dependency",
}


local function get_download_url(package, reason)
	local base_url = core.settings:get("contentdb_url")
	local ret = base_url .. ("/packages/%s/releases/%d/download/"):format(
			package.url_part, package.release)
	if reason then
		ret = ret .. "?reason=" .. reason
	end
	return ret
end


local function download_and_extract(param)
	local package = param.package

	local filename = core.get_temp_path(true)
	if filename == "" or not core.download_file(param.url, filename) then
		core.log("error", "Downloading " .. dump(param.url) .. " failed")
		return {
			msg = fgettext_ne("Failed to download \"$1\"", package.title)
		}
	end

	local tempfolder = core.get_temp_path()
	if tempfolder ~= "" and not core.extract_zip(filename, tempfolder) then
		tempfolder = ""
	end
	os.remove(filename)
	if tempfolder == "" then
		return {
			msg = fgettext_ne("Failed to extract \"$1\" (unsupported file type or broken archive)", package.title),
		}
	end

	return {
		path = tempfolder
	}
end


local function start_install(package, reason)
	local params = {
		package = package,
		url = get_download_url(package, reason),
	}

	contentdb.number_downloading = contentdb.number_downloading + 1

	local function callback(result)
		if result.msg then
			gamedata.errormessage = result.msg
		else
			local path, msg = pkgmgr.install_dir(package.type, result.path, package.name, package.path)
			core.delete_dir(result.path)
			if not path then
				gamedata.errormessage = fgettext_ne("Error installing \"$1\": $2", package.title, msg)
			else
				core.log("action", "Installed package to " .. path)

				local conf_path
				local name_is_title = false
				if package.type == "mod" then
					local actual_type = pkgmgr.get_folder_type(path)
					if actual_type.type == "modpack" then
						conf_path = path .. DIR_DELIM .. "modpack.conf"
					else
						conf_path = path .. DIR_DELIM .. "mod.conf"
					end
				elseif package.type == "game" then
					conf_path = path .. DIR_DELIM .. "game.conf"
					name_is_title = true
				elseif package.type == "txp" then
					conf_path = path .. DIR_DELIM .. "texture_pack.conf"
				end

				if conf_path then
					local conf = Settings(conf_path)
					if not conf:get("title") then
						conf:set("title", package.title)
					end
					if not name_is_title then
						conf:set("name", package.name)
					end
					if not conf:get("description") then
						conf:set("description", package.short_description)
					end
					conf:set("author",     package.author)
					conf:set("release",    package.release)
					conf:write()
				end
			end
		end

		package.downloading = false

		contentdb.number_downloading = contentdb.number_downloading - 1

		local next = contentdb.download_queue[1]
		if next then
			table.remove(contentdb.download_queue, 1)

			start_install(next.package, next.reason)
		end

		ui.update()
	end

	package.queued = false
	package.downloading = true

	if not core.handle_async(download_and_extract, params, callback) then
		core.log("error", "ERROR: async event failed")
		gamedata.errormessage = fgettext_ne("Failed to download $1", package.name)
		return
	end
end


function contentdb.queue_download(package, reason)
	if package.queued or package.downloading then
		return
	end

	local max_concurrent_downloads = tonumber(core.settings:get("contentdb_max_concurrent_downloads"))
	if contentdb.number_downloading < math.max(max_concurrent_downloads, 1) then
		start_install(package, reason)
	else
		table.insert(contentdb.download_queue, { package = package, reason = reason })
		package.queued = true
	end
end


function contentdb.get_package_by_id(id)
	return contentdb.package_by_id[id]
end


local function get_raw_dependencies(package)
	if package.type ~= "mod" then
		return {}
	end
	if package.raw_deps then
		return package.raw_deps
	end

	local url_fmt = "/api/packages/%s/dependencies/?only_hard=1&protocol_version=%s&engine_version=%s"
	local version = core.get_version()
	local base_url = core.settings:get("contentdb_url")
	local url = base_url .. url_fmt:format(package.url_part, core.get_max_supp_proto(), core.urlencode(version.string))

	local http = core.get_http_api()
	local response = http.fetch_sync({ url = url })
	if not response.succeeded then
		core.log("error", "Unable to fetch dependencies for " .. package.url_part)
		return
	end

	local data = core.parse_json(response.data) or {}

	for id, raw_deps in pairs(data) do
		local package2 = contentdb.package_by_id[id:lower()]
		if package2 and not package2.raw_deps then
			package2.raw_deps = raw_deps

			for _, dep in pairs(raw_deps) do
				local packages = {}
				for i=1, #dep.packages do
					packages[#packages + 1] = contentdb.package_by_id[dep.packages[i]:lower()]
				end
				dep.packages = packages
			end
		end
	end

	return package.raw_deps
end


function contentdb.has_hard_deps(package)
	local raw_deps = get_raw_dependencies(package)
	if not raw_deps then
		return nil
	end

	for i=1, #raw_deps do
		if not raw_deps[i].is_optional then
			return true
		end
	end

	return false
end


-- Recursively resolve dependencies, given the installed mods
local function resolve_dependencies_2(raw_deps, installed_mods, out)
	local function resolve_dep(dep)
		-- Check whether it's already installed
		if installed_mods[dep.name] then
			return {
				is_optional = dep.is_optional,
				name = dep.name,
				installed = true,
			}
		end

		-- Find exact name matches
		local fallback
		for _, package in pairs(dep.packages) do
			if package.type ~= "game" then
				if package.name == dep.name then
					return {
						is_optional = dep.is_optional,
						name = dep.name,
						installed = false,
						package = package,
					}
				elseif not fallback then
					fallback = package
				end
			end
		end

		-- Otherwise, find the first mod that fulfills it
		if fallback then
			return {
				is_optional = dep.is_optional,
				name = dep.name,
				installed = false,
				package = fallback,
			}
		end

		return {
			is_optional = dep.is_optional,
			name = dep.name,
			installed = false,
		}
	end

	for _, dep in pairs(raw_deps) do
		if not dep.is_optional and not out[dep.name] then
			local result  = resolve_dep(dep)
			out[dep.name] = result
			if result and result.package and not result.installed then
				local raw_deps2 = get_raw_dependencies(result.package)
				if raw_deps2 then
					resolve_dependencies_2(raw_deps2, installed_mods, out)
				end
			end
		end
	end

	return true
end


-- Resolve dependencies for a package, calls the recursive version.
function contentdb.resolve_dependencies(package, game)
	assert(game)

	local raw_deps = get_raw_dependencies(package)
	local installed_mods = {}

	local mods = {}
	pkgmgr.get_game_mods(game, mods)
	for _, mod in pairs(mods) do
		installed_mods[mod.name] = true
	end

	for _, mod in pairs(pkgmgr.global_mods:get_list()) do
		installed_mods[mod.name] = true
	end

	local out = {}
	if not resolve_dependencies_2(raw_deps, installed_mods, out) then
		return nil
	end

	local retval = {}
	for _, dep in pairs(out) do
		retval[#retval + 1] = dep
	end

	table.sort(retval, function(a, b)
		return a.name < b.name
	end)

	return retval
end


local function fetch_pkgs(params)
	local version = core.get_version()
	local base_url = core.settings:get("contentdb_url")
	local url = base_url ..
			"/api/packages/?type=mod&type=game&type=txp&protocol_version=" ..
			core.get_max_supp_proto() .. "&engine_version=" .. core.urlencode(version.string)

	for _, item in pairs(core.settings:get("contentdb_flag_blacklist"):split(",")) do
		item = item:trim()
		if item ~= "" then
			url = url .. "&hide=" .. core.urlencode(item)
		end
	end

	local languages
	local current_language = core.get_language()
	if current_language ~= "" then
		languages = { current_language, "en;q=0.8" }
	else
		languages = { "en" }
	end

	local http = core.get_http_api()
	local response = http.fetch_sync({
		url = url,
		extra_headers = {
			"Accept-Language: " .. table.concat(languages, ", ")
		},
	})
	if not response.succeeded then
		return
	end

	local packages = core.parse_json(response.data)
	if not packages or #packages == 0 then
		return
	end
	local aliases = {}

	for _, package in pairs(packages) do
		local name_len = #package.name
		-- This must match what contentdb.update_paths() does!
		package.id = package.author:lower() .. "/"
		if package.type == "game" and name_len > 5 and package.name:sub(name_len - 4) == "_game" then
			package.id = package.id .. package.name:sub(1, name_len - 5)
		else
			package.id = package.id .. package.name
		end

		package.url_part = core.urlencode(package.author) .. "/" .. core.urlencode(package.name)

		if package.aliases then
			for _, alias in ipairs(package.aliases) do
				-- We currently don't support name changing
				local suffix = "/" .. package.name
				if alias:sub(-#suffix) == suffix then
					aliases[alias:lower()] = package.id
				end
			end
		end
	end

	return { packages = packages, aliases = aliases }
end


function contentdb.fetch_pkgs(callback)
	contentdb.loading = true
	core.handle_async(fetch_pkgs, nil, function(result)
		if result then
			contentdb.load_ok = true
			contentdb.load_error = false
			contentdb.packages = result.packages
			contentdb.packages_full = result.packages
			contentdb.packages_full_unordered = result.packages
			contentdb.aliases = result.aliases

			for _, package in ipairs(result.packages) do
				contentdb.package_by_id[package.id] = package
			end
		else
			contentdb.load_error = true
		end

		contentdb.loading = false
		callback(result)
	end)
end


function contentdb.update_paths()
	local mod_hash = {}
	pkgmgr.refresh_globals()
	for _, mod in pairs(pkgmgr.global_mods:get_list()) do
		local cdb_id = pkgmgr.get_contentdb_id(mod)
		if cdb_id then
			mod_hash[contentdb.aliases[cdb_id] or cdb_id] = mod
		end
	end

	local game_hash = {}
	pkgmgr.update_gamelist()
	for _, game in pairs(pkgmgr.games) do
		local cdb_id = pkgmgr.get_contentdb_id(game)
		if cdb_id then
			game_hash[contentdb.aliases[cdb_id] or cdb_id] = game
		end
	end

	local txp_hash = {}
	for _, txp in pairs(pkgmgr.get_texture_packs()) do
		local cdb_id = pkgmgr.get_contentdb_id(txp)
		if cdb_id then
			txp_hash[contentdb.aliases[cdb_id] or cdb_id] = txp
		end
	end

	for _, package in pairs(contentdb.packages_full) do
		local content
		if package.type == "mod" then
			content = mod_hash[package.id]
		elseif package.type == "game" then
			content = game_hash[package.id]
		elseif package.type == "txp" then
			content = txp_hash[package.id]
		end

		if content then
			package.path = content.path
			package.installed_release = content.release or 0
		else
			package.path = nil
			package.installed_release = nil
		end
	end
end


function contentdb.sort_packages()
	local ret = {}

	-- Add installed content
	for _, pkg in ipairs(contentdb.packages_full_unordered) do
		if pkg.path then
			ret[#ret + 1] = pkg
		end
	end

	-- Sort installed content first by "is there an update available?", then by title
	table.sort(ret, function(a, b)
		local a_updatable = a.installed_release < a.release
		local b_updatable = b.installed_release < b.release
		if a_updatable and not b_updatable then
			return true
		elseif b_updatable and not a_updatable then
			return false
		end

		return a.title < b.title
	end)

	-- Add uninstalled content
	for _, pkg in ipairs(contentdb.packages_full_unordered) do
		if not pkg.path then
			ret[#ret + 1] = pkg
		end
	end

	contentdb.packages_full = ret
end


function contentdb.filter_packages(query, by_type)
	if query == "" and by_type == nil then
		contentdb.packages = contentdb.packages_full
		return
	end

	local keywords = {}
	for word in query:lower():gmatch("%S+") do
		table.insert(keywords, word)
	end

	local function matches_keywords(package)
		for k = 1, #keywords do
			local keyword = keywords[k]

			if string.find(package.name:lower(), keyword, 1, true) or
					string.find(package.title:lower(), keyword, 1, true) or
					string.find(package.author:lower(), keyword, 1, true) or
					string.find(package.short_description:lower(), keyword, 1, true) then
				return true
			end
		end

		return false
	end

	contentdb.packages = {}
	for _, package in pairs(contentdb.packages_full) do
		if (query == "" or matches_keywords(package)) and
				(by_type == nil or package.type == by_type) then
			contentdb.packages[#contentdb.packages + 1] = package
		end
	end
end