require "json"
require "uuid"
require "uuid/json"
require "baguette-crystal-base"
require "./service.cr"

require "dodb"

class DNSManager::Storage
	getter domains                 : DODB::CachedDataBase(Domain)
	getter domains_by_name         : DODB::Index(Domain)
	getter domains_by_share_key    : DODB::Index(Domain)
	getter domains_by_transfer_key : DODB::Index(Domain)
	getter domains_by_owners       : DODB::Tags(Domain)

	getter zones             : DODB::CachedDataBase(Zone)
	getter zones_by_domain   : DODB::Index(Zone)

	getter tokens            : DODB::CachedDataBase(Token)
	getter tokens_by_uuid    : DODB::Index(Token)
	getter tokens_by_domain  : DODB::Partition(Token)

	getter root              : String
	getter zonefiledir       : String

	property dnsmanagerd : DNSManager::Service? = nil

	def dnsmanagerd() : DNSManager::Service
		@dnsmanagerd.not_nil!
	rescue
		raise Exception.new "dnsmanagerd not defined"
	end

	def initialize(@root : String, reindex : Bool = false)
		@domains                 = DODB::CachedDataBase(Domain).new "#{@root}/domains"
		@domains_by_name         = @domains.new_index "name", &.name
		@domains_by_share_key    = @domains.new_nilable_index "share-key", do |d|
 				if k = d.share_key
 					k
 				else
 					DODB.no_index
 				end
			end
		@domains_by_transfer_key = @domains.new_nilable_index "transfer-key", do |d|
 				if k = d.transfer_key
 					k
 				else
 					DODB.no_index
 				end
			end
		@domains_by_owners = @domains.new_tags "owners", &.owners.map &.to_s
		@zones             = DODB::CachedDataBase(Zone).new "#{@root}/zones"
		@zones_by_domain   = @zones.new_index "domain", &.domain
		@tokens            = DODB::CachedDataBase(Token).new "#{@root}/tokens"
		@tokens_by_uuid    = @tokens.new_index "uuid", &.uuid
		@tokens_by_domain  = @tokens.new_partition "domain", &.domain

		@zonefiledir = "#{@root}/bind9-zones"
		Dir.mkdir_p @zonefiledir

		Baguette::Log.info "storage initialized"

		if reindex
			Baguette::Log.debug "Reindexing domains..."
			@domains.reindex_everything!
			Baguette::Log.debug "Reindexing zones..."
			@zones.reindex_everything!
			Baguette::Log.debug "Reindexing tokens..."
			@tokens.reindex_everything!
			Baguette::Log.debug "Reindexed!"
		end
	end

	def generate_zonefile_(domain : String) : Nil
		zone = zone_must_exist! domain

		# Safe write.
		filename_final = "#{@zonefiledir}/#{zone.domain}"
		filename_wip   = "#{filename_final}.wip"
		Baguette::Log.info "writing zone file #{filename_final}"

		File.open(filename_wip, "w") do |file|
			zone.to_bind9 file
		end

		# Rename WIP filename to final file name.
		File.rename filename_wip, filename_final
	end

	# Only an admin can access this function.
	def generate_zonefile(domain : String) : IPC::JSON
		generate_zonefile_ domain
		Response::Success.new
	end

	# Only an admin can access this function.
	def generate_all_zonefiles() : IPC::JSON
		Baguette::Log.info "writing all zone files in #{@zonefiledir}/"
		zones.each do |zone|
			generate_zonefile_ zone.domain
		end
		Response::Success.new
	end

	def get_generated_zonefile(user_id : UserDataID, domain : String) : IPC::JSON

		user_must_exist! user_id
		zone      = zone_must_exist! domain
		user_should_own! user_id, zone.domain

		io = IO::Memory.new
		zone.to_bind9 io
		Response::GeneratedZone.new domain, (String.new io.buffer, io.pos)
	end

	def new_domain(accepted_domains   : Array(String),
	               template_directory : String,
	               user_id            : UserDataID,
	               domain             : String) : IPC::JSON

		user_must_exist! user_id

		# Prevent future very confusing errors.
		domain = domain.downcase

		return Response::DomainAlreadyExists.new if zones_by_domain.get? domain

		# Verify if the domain is acceptable.
		matching_domains = accepted_domains.select { |adomain| domain.ends_with? adomain }
		unless matching_domains.size > 0
			Baguette::Log.warning "trying to add an unacceptable domain: #{domain}"
			return Response::UnacceptableDomain.new
		end

		matching_domains.each do |md|
			# Prevent empty domains (from crafted requests) to be accepted.
			return Response::InvalidDomainName.new unless (domain.chomp md).size > 1
			Baguette::Log.info "Add new domain #{domain} (matching domain #{md})"
		end

		# Verify the domain name validity.
		return Response::InvalidDomainName.new unless Zone.is_domain_valid? domain

		# Fill a template zone.
		tld = matching_domains.pop
		default_zone = Zone.from_json File.read "#{template_directory}/#{tld}.json"

		# Replace domain by the real domain.
		default_zone.replace_domain domain

		#
		# Actually write data on-disk.
		#

		# Add the new domain.
		the_new_domain = Domain.new domain
		the_new_domain.owners = [user_id]
		@domains << the_new_domain

		# Add the new zone in the database.
		zones_by_domain.update_or_create domain, default_zone

		Response::DomainAdded.new domain
	end

	def ask_share_token(user_id : UserDataID, domain_name : String)
		user_must_exist! user_id
		user_should_own! user_id, domain_name

		domain = @domains_by_name.get domain_name
		if domain.share_key.nil?
			domain.share_key = UUID.random.to_s
			@domains_by_name.update_or_create domain_name, domain
			Response::DomainChanged.new domain
		else
			Response::Error.new "The domain already have a share key."
		end
	end

	def ask_transfer_token(user_id : UserDataID, domain_name : String)
		user_must_exist! user_id
		user_should_own! user_id, domain_name

		domain = @domains_by_name.get domain_name
		if domain.transfer_key.nil?
			domain.transfer_key = UUID.random.to_s
			@domains_by_name.update_or_create domain_name, domain
			Response::DomainChanged.new domain
		else
			Response::Error.new "The domain already have a transfer key."
		end
	end

	# Check the domain owners.
	# In case there's only the requesting user, allow him to gain full control.
	def ask_unshare_domain(user_id : UserDataID, domain_name : String)
		user_must_exist! user_id
		user_should_own! user_id, domain_name

		domain = @domains_by_name.get domain_name
		if domain.owners.size == 1 && domain.owners[0] == user_id
			domain.share_key = nil
			@domains_by_name.update_or_create domain_name, domain
			Response::DomainChanged.new domain
		else
			Response::Error.new "You are not the only owner."
		end
	end

	def gain_ownership(user_id : UserDataID, uuid : String)
		user_must_exist! user_id

		if domain = @domains_by_share_key.get? uuid
			if domain.owners.includes? user_id
				return Response::Error.new "You already own this domain."
			end
			domain.owners << user_id
			@domains_by_name.update_or_create domain.name, domain
			Response::DomainChanged.new domain
		elsif domain = @domains_by_transfer_key.get? uuid
			if domain.owners.includes? user_id
				return Response::Error.new "You already own this domain."
			end
			domain.transfer_key = nil
			domain.owners = [user_id]
			@domains_by_name.update_or_create domain.name, domain
			Response::DomainChanged.new domain
		else
			Response::Error.new "There is no key with this UUID."
		end
	end

	def add_or_update_zone(user_id : UserDataID, zone : Zone) : IPC::JSON
		user_must_exist! user_id

		# Test zone validity.
		if errors = zone.get_errors?
			Baguette::Log.warning "zone #{zone.domain} update with errors: #{errors}"
			return Response::InvalidZone.new errors
		end

		# Does the zone already exist?
		if z = zones_by_domain.get? zone.domain
			user_should_own! user_id, z.domain
		else
			# Add the domain to the user's domain.
			domains << Domain.new zone.domain
		end

		# Add -or replace- the zone.
		zones_by_domain.update_or_create zone.domain, zone

		Response::Success.new
	end

	def add_rr(user_id : UserDataID, domain : String, rr : Zone::ResourceRecord) : IPC::JSON
		user_must_exist! user_id
		zone      = zone_must_exist! domain
		user_should_own! user_id, domain

		# Test RR validity.
		rr.get_errors.tap do |errors|
			unless errors.empty?
				Baguette::Log.warning "add RR with errors: #{errors}"
				return Response::InvalidRR.new errors
			end
		end

		zone << rr

		update_zone zone

		Response::RRAdded.new zone.domain, rr
	end

	# Any modification of the zone must be performed here.
	# This function updates the SOA serial before storing the modified zone.
	def update_zone(zone : Zone)
		zone.update_serial
		zones_by_domain.update_or_create zone.domain, zone
	end

	def update_rr(user_id : UserDataID, domain : String, rr : Zone::ResourceRecord) : IPC::JSON
		user_must_exist! user_id
		zone      = zone_must_exist! domain
		user_should_own! user_id, domain

		zone.rr_not_readonly! rr.rrid

		# Test RR validity.
		rr.get_errors.tap do |errors|
			unless errors.empty?
				Baguette::Log.warning "update RR with errors: #{errors}"
				return Response::InvalidRR.new errors
			end
		end

		zone.update_rr rr

		update_zone zone

		Response::RRUpdated.new domain, rr
	end

	def delete_rr(user_id : UserDataID, domain : String, rrid : UInt32) : IPC::JSON
		user_must_exist! user_id
		zone      = zone_must_exist! domain
		user_should_own! user_id, domain

		rr = zone.rr_not_readonly! rrid

		# Remove token from the db.
		if token_uuid = rr.token
			tokens_by_uuid.delete token_uuid
		end

		zone.delete_rr rrid
		update_zone zone

		Response::RRDeleted.new rrid
	end

	def delete_domain(user_id : UserDataID, domain_name : String) : IPC::JSON
		user_must_exist! user_id
		zone_must_exist! domain_name
		user_should_own! user_id, domain_name

		domain = @domains_by_name.get domain_name
		# The user isn't the only owner, just remove him from the list of owners.
		if domain.owners.size > 1
			domain.owners.select! { |o| o != user_id }
			@domains_by_name.update_or_create domain_name, domain

			# Not really a domain deletion, but that'll do the trick.
			return Response::DomainDeleted.new domain_name
		end

		# Remove this domain_name from the list of user's domains.
		domains_by_name.delete domain_name

		# Remove the related zone and their registered tokens.
		zones_by_domain.delete domain_name
		tokens_by_domain.delete domain_name

		Response::DomainDeleted.new domain_name
	end

	# Get all removed users from `authd`, list all their domains and remove their data from `dnsmanagerd`.
	def get_orphan_domains(user_id : UserDataID) : IPC::JSON
		user_must_be_admin! user_id

#		Baguette::Log.debug "list all orphan domains (long computation)"
#		orphans = [] of String
#		user_data.each do |user|
#			begin
#				dnsmanagerd().authd.get_user? user.uid
#			rescue e
#				Baguette::Log.warning "no authd info on user #{user.uid}: #{e} (removing this user)"
#				Baguette::Log.debug "user #{user.uid} had #{user.domains.size} domains"
#				user.domains.each do |domain|
#					orphans << domain
#				end
#				wipe_user_data user
#			end
#		end
#		Baguette::Log.debug "total: #{orphans.size} orphans"
#
#		Response::OrphanDomainList.new orphans
		Response::Error.new "Not implemented."
	end

	def get_zone(user_id : UserDataID, domain : String) : IPC::JSON
		user_must_exist! user_id
		zone      = zone_must_exist! domain
		user_should_own! user_id, domain

		Response::Zone.new zone
	end

	def wipe_user_data(user_id : UserDataID)
		domains_by_owners.get(user_id.to_s).each do |domain|
			domain.owners.delete user_id

			# Remove the user's domain when he is the only owner.
			if domain.owners.empty?
				@domains_by_name.delete domain.name
				@tokens_by_domain.delete domain.name
				@zones_by_domain.delete domain.name
			else
				@domains_by_name.update_or_create domain.name, domain
			end
		end
	rescue e
		Baguette::Log.error "while removing a domain: #{e}"
	end

	def delete_user_data(user_id : UserDataID, user_to_delete : UserDataID?) : IPC::JSON
		user_must_exist! user_id
		user_id_to_delete = if u = user_to_delete
			user_must_be_admin! user_id
			Baguette::Log.info "Admin #{user_id} removes data of user #{u}."
			user_must_exist! u
			u
		else
			Baguette::Log.info "User #{user_id} terminates his account."
			user_id
		end

		wipe_user_data user_id_to_delete

		Response::Success.new
	end

	def user_domains(user_id : UserDataID) : Array(Domain)
		user_must_exist! user_id
		domains_by_owners.get(user_id.to_s)
	end

	# TODO: is the user known from authd?
	def user_must_exist!(user_id : UserDataID)
		dnsmanagerd().authd.get_user? user_id
	end

	def user_must_be_admin!(user_id : UserDataID) : Nil
		dnsmanagerd().assert_permissions! user_id, "*", AuthD::User::PermissionLevel::Admin
	end

	def zone_must_exist!(domain : String) : Zone
		zone = zones_by_domain.get? domain
		raise DomainNotFoundException.new unless zone
		zone
	end

	# Owning a domain means to be in the owners' list of the domain.
	# TODO: accept admin users to override this test.
	def user_should_own!(user_id : UserDataID, domain : String) : Nil
		d = domains_by_name.get domain
		unless d.owners.includes? user_id
			raise NoOwnershipException.new
		end
	end

	def new_token(user_id : UserDataID, domain : String, rrid : UInt32) : IPC::JSON
		user_must_exist! user_id
		zone      = zone_must_exist! domain
		user_should_own! user_id, domain

		rr = zone.rr_must_exist! rrid

		old_token = rr.token

		# 1. create token
		token = Token.new domain, rrid

		# 2. add token to the RR.
		rr.token = token.uuid
		zone.update_rr rr

		# 3. update the zone (no need to call `update_zone` to change the zone serial).
		zones_by_domain.update_or_create zone.domain, zone

		# 4. if there is an old token, remove it.
		if old_token_uuid = old_token
			tokens_by_uuid.delete old_token_uuid
		end

		# 5. add token to the db.
		@tokens << token

		Response::RRUpdated.new domain, rr
	end

	def token_must_exist!(token_uuid : String) : Token
		token = tokens_by_uuid.get? token_uuid
		raise TokenNotFoundException.new unless token
		token
	end

	def use_token(token_uuid : String, address : String) : IPC::JSON
		token = token_must_exist! token_uuid
		zone = zone_must_exist! token.domain
		rr = zone.rr_must_exist! token.rrid

		# Same address, no need to change anything.
		return Response::Success.new if rr.target == address

		case rr
		when Zone::A
			return Response::Error.new "invalid ipv4" unless Zone.is_ipv4_address_valid? address
			rr.target = address
			zone.update_rr rr
			zones_by_domain.update_or_create zone.domain, zone
			Response::Success.new
		when Zone::AAAA
			return Response::Error.new "invalid ipv6" unless Zone.is_ipv6_address_valid? address
			rr.target = address
			zone.update_rr rr
			update_zone zone
			Response::Success.new
		else
			Response::Error.new "use token on invalid entry (not A or AAAA)"
		end
	end
end

require "./storage/*"