require "uuid"
require "uri"
require "file_utils"

require "specfileparser"

require "./context.cr"
require "./package.cr"
require "./instructions.cr"
require "./sources.cr"
require "./exception.cr"

# 🤔
class URI
	def basename
		File.basename path
	end
end

module FileUtils
	def self.find(directory, &block : Proc(String, Nil))
		Dir.each_child directory do |child|
			child_path = directory + "/" + child
			yield child_path

			if File.directory? child_path
				self.find child_path, &block
			end
		end
	end
end

class Package::Recipe
	@context : Context

	# Core recipe informations.
	getter name          : String
	getter version       : String
	getter release       = 1

	property url         : String?
	property description : String?

	# Informations not specific to individual packages.
	getter sources       : Sources
	getter packages      : Array(Package)

	property packager    : String?
	property maintainer  : String?
	getter contributors  = Array(String).new

	# Relations to other packages.
	# FIXME: `dependencies` needs splitting between run-time and build-time.
	getter run_dependencies   = Array(String).new
	getter build_dependencies = Array(String).new
	getter provides      = Array(String).new
	getter conflicts     = Array(String).new

	# Build instructions, helpers and other build-only data.
	setter dirname       : String? # matching getter defined manually later.
	getter instructions  = Instructions.new
	getter options       = Hash(String, String).new

	getter sources       = Sources.new
	getter packages      = Array(Package).new

	@working_uuid        : UUID = UUID.random

	def initialize(@context, @name, @version)
	end

	def self.new(context, name, version)
		instance = Recipe.allocate.tap &.initialize(context, name, version)

		instance.packages << Package.new instance, false, instance.fake_root_directory

		instance
	end

	def initialize(@context, filename : String)
		specs = SpecFileParser.parse filename, {
			"pkg" => fake_root_directory
		}

		name : String? = nil
		version : String? = nil

		raise "Could not parse `#{filename}`" if specs.nil?

		specs.assignments.each do |key, value|
			case key
			when "name"
				name = value.as_s
			when "version"
				version = value.as_s
			when "release"
				@release = value.as_s.to_i
			when "url"
				@url = value.as_s
			when "description"
				@description = value.as_s_or_ls
			when "packager"
				@packager = value.as_s
			when "maintainer"
				@maintainer = value.as_s
			when "sources"
				value.as_a_or_s.each do |source|
					@sources << source
				end
			when "configure"
				@instructions.configure << value.as_s_or_ls
			when "build"
				@instructions.build << value.as_s_or_ls
			when "install"
				@instructions.install << value.as_s_or_ls
			when "dirname"
				@dirname = value.as_s
			when "dependencies"
				value.as_a_or_s.each do |atom|
					@run_dependencies << atom
					@build_dependencies << atom
				end
			when "build-dependencies"
				value.as_a_or_s.each do |atom|
					@build_dependencies << atom
				end
			when "run-dependencies"
				value.as_a_or_s.each do |atom|
					@run_dependencies << atom
				end
			when "conflicts"
				value.as_a_or_s.each do |atom|
					@conflicts << atom
				end
			when "provides"
				value.as_a_or_s.each do |atom|
					@provides << atom
				end
			when "options"
				value.as_a_or_s.each do |option|
					match  = option.split(':').map(
						&.gsub(/^[ \t]*/, "").gsub(/[ \t]*$/, ""))

					if match.size != 2
						puts "WARNING: misformed option: #{option}"
						next
					end

					key, value = match

					@options[key] = value
				end
			end
		end

		raise "`name` was not provided" unless name
		raise "`version` was not provided" unless version

		@name = name
		@version = version

		# Packages can only be created once @name and @version exist!
		@packages << Package.new self, false, fake_root_directory

		specs.sections.each do |section|
			if section.name == "split"
				@packages << Package.new self, section
			end
		end
	end

	def working_directory
		"#{@context.working_directory}/#{@working_uuid}"
	end

	def building_directory
		"#{working_directory}/build"
	end

	def fake_root_directory
		"#{working_directory}/root"
	end

	def dirname
		@dirname || "#{name}-#{version}"
	end

	def download
		sources.each do |url|
			unless File.exists? url.basename
				status = @context.run @context.sources_directory, "wget", [ url.to_s, "-O", url.basename ]

				raise DownloadError.new self, url unless status.success?
			end
		end
	end

	def extract
		Dir.mkdir_p building_directory

		sources.each do |url|
			basename = url.basename

			status = @context.run(
				building_directory,
				"bsdtar", [
					"xvf",
					@context.sources_directory + "/" + url.basename
				]
			)

			raise ExtractionError.new self, url unless status.success?
		end
	end

	# TODO:
	#   - Export packaging directory in $PKG.
	#   - Add (pre|post)-(configure|build|install) instructions.
	#   - Have some instructions be non-critical, like the (pre|post] ones.
	#   - Be careful about return values, flee from everything if something
	#     goes somehow wrong.
	#   - Make things thread-safe. (those ENV[]= calls are definitely not)
	def build
		Dir.mkdir_p fake_root_directory

		ENV["PKG"] = fake_root_directory

		# Safety precautions.
		old_dir = Dir.current

		instructions.to_a.each do |instruction|
			if instruction.run(@context, self).failed?
				raise BuildError.new self, "Building (#{instruction.phase} phase) failed."
				break
			end
		end

		Dir.cd old_dir

		ENV["PKG"] = nil

		if Dir.children(fake_root_directory).size == 0
			raise BuildError.new self, "No file was installed in the fake root."
		end

		do_splits
	end

	private def do_splits
		(@packages + auto_splits).each do |package|
			next if package == @packages[0]

			files = package.files || [] of String
			file_patterns = package.file_patterns || [] of Regex

			files_to_split = [] of String

			files.each do |file|
				origin = "#{fake_root_directory}#{file}"

				if File.exists? origin
					files_to_split << file
				end
			end

			FileUtils.find fake_root_directory do |file|
				file = file[fake_root_directory.size..file.size]
				files_to_split << file if file_patterns.any? &.match file
			end

			# FIXME: What do we do if those are not on the filesystem?
			files_to_split.each do |file|
				origin = "#{fake_root_directory}#{file}"
				destination ="#{package.fake_root_directory}#{file}"

				Dir.mkdir_p File.dirname destination

				FileUtils.mv(
					"#{fake_root_directory}#{file}",
					"#{package.fake_root_directory}#{file}"
				)

				puts file
				@context.run "find", [
					"#{package.fake_root_directory}/#{file}"
				]
			end
		end
	end

	def auto_splits : Array(Package)
		@context.splitter_backends.compact_map do |backend|
			backend.create_split self
		end
	end

	# TODO:
	#  - Errors management. Stop at first failure?
	#  - Splits. This should be done between #build and #package.
	def package
		# This tries to build them all and stops at the first failure
		# (failures are currently reported by Context#package)
		(@packages + auto_splits).each do |package|
			if package.automatic && ! File.exists? package.fake_root_directory
				next
			end

			unless @context.package package
				raise PackagingError.new self, package
			end
		end
	end

	def clean
		FileUtils.rm_rf building_directory
		FileUtils.rm_rf fake_root_directory
	end

	def to_s
		"#{name}-#{version}"
	end

	def to_spec_s
		spec = [
			"name: #{name}",
			"version: #{version}",
			"release: #{release}"
		].join("\n") + "\n"

		if @sources.size == 1
			spec += "sources: #{sources[0].to_s.gsub @version, "%{version}"}\n"
		end

		if maintainer
			spec += "maintainer: #{maintainer}\n"
		end
		if packager
			spec += "packager: #{packager}\n"
		end

		if @options.size > 0
			spec += "options:\n"
			@options.each do |key, value|
				value = value.gsub fake_root_directory, "%{pkg}"
				spec += "\t- #{key}: #{value}\n"
			end
			spec += "\n" # Limitation of the current implementation.
		end

		if @dependencies.size > 0
			spec += "dependencies:\n"
			@dependencies.each do |dep|
				spec += "\t- #{dep}\n"
			end
			spec += "\n"
		end

		if @dirname
			spec += "dirname: #{@dirname}\n"
		end

		[
			{"configure", @instructions.configure},
			{"build",     @instructions.build},
			{"install",   @instructions.install}
		].each do |name, instructions|
			if instructions.size > 0
				spec += "@#{name}\n"
				instructions.each do |line|
					line = line.gsub /^\t* *\n/, ""
					line = line.gsub /\n *\t*\n/, "\n"
					line = line.gsub /\n *\t*$/, ""
					line = line.gsub fake_root_directory, "%{pkg}"
					line = line.gsub name, "%{name}"
					line = line.gsub version, "%{version}"
					line = line.gsub dirname, "%{dirname}"
					line = line.gsub(/^[\t ]*/, "").gsub(/\n\t*/, "\n\t")
					spec += "\t#{line}\n"
				end
				spec += "\n" # Limitation of the current implementation.
			end
		end

		spec
	end
end