require "csv"

class Entry < ApplicationRecord
	belongs_to :user
	
	# ------------------------------------------------------------
	# Konstanten
	# ------------------------------------------------------------
	
	PRAKTIKUMSTYPEN = %w[
    propädeutikum
    fachspezifikum
    mediation
  ].freeze
	
	ENTRY_ARTEN = [
		              # Allgemein
		              "Praktikum",
		              "Selbsterfahrung",
		              "Supervision",
		              "Fortbildung",
		              "Semesterkosten",
		              
		              # Mediation
		              "Präsenzmodul",
		              "Peergruppenarbeit",
		              "Fallarbeit",
		              "Praxisseminare",
		              "Literatur- und Selbststudium",
		              
		              # Fachspezifikum
		              "Gruppenselbsterfahrung",
		              "Theorie/Methodikseminare",
		              "Peergruppensupervision",
		              "Einzel-/Kleingruppensupervision",
		              "Eigenständige Tätigkeit"
	              ].freeze
	
	LEGACY_ENTRY_ART_ALIASES = {
		                           "Peergroup"  => "Peergruppenarbeit",
		                           "Peer-Gruppe" => "Peergruppenarbeit"
	                           }.freeze
	
	# ------------------------------------------------------------
	# Validierungen
	# ------------------------------------------------------------
	
	validates :date,
	          presence: true
	
	validates :hours,
	          numericality: {
		          only_integer: true,
		          greater_than_or_equal_to: 0
	          },
	          unless: -> { start_time.present? && end_time.nil? }
	
	validates :minutes,
	          numericality: {
		          only_integer: true,
		          greater_than_or_equal_to: 0,
		          less_than: 60
	          },
	          unless: -> { start_time.present? && end_time.nil? }
	
	validates :praktikums_typ,
	          inclusion: { in: PRAKTIKUMSTYPEN }
	
	validates :entry_art,
	          inclusion: { in: ENTRY_ARTEN }
	
	validates :distance_km,
	          numericality: {
		          only_integer: true,
		          greater_than_or_equal_to: 0
	          },
	          allow_nil: true
	
	# ------------------------------------------------------------
	# Callbacks
	# ------------------------------------------------------------
	
	before_validation :normalize_legacy_entry_art
	before_save :normalize_time
	
	after_initialize :set_default_date,
	                 if: :new_record?
	
	# ------------------------------------------------------------
	# Scopes
	# ------------------------------------------------------------
	
	scope :propädeutikum, -> {
		where(praktikums_typ: "propädeutikum")
	}
	
	scope :fachspezifikum, -> {
		where(praktikums_typ: "fachspezifikum")
	}
	
	scope :mediation, -> {
		where(praktikums_typ: "mediation")
	}
	
	scope :peergruppenarbeit, -> {
		where(entry_art: "Peergruppenarbeit")
	}
	
	scope :fallarbeit, -> {
		where(entry_art: "Fallarbeit")
	}
	
	scope :praxisseminare, -> {
		where(entry_art: "Praxisseminare")
	}
	
	scope :praesenzmodule, -> {
		where(entry_art: "Präsenzmodul")
	}
	
	scope :literatur_und_selbststudium, -> {
		where(entry_art: "Literatur- und Selbststudium")
	}
	
	# ------------------------------------------------------------
	# Defaults
	# ------------------------------------------------------------
	
	def set_default_date
		self.date ||= Date.current
	end
	
	# ------------------------------------------------------------
	# Zeit
	# ------------------------------------------------------------
	
	def total_minutes
		hours.to_i * 60 + minutes.to_i
	end
	
	def total_minutes_including_break
		return nil unless start_time.present? && end_time.present?
		
		worked_minutes =
			((end_time - start_time) / 60).to_i
		
		worked_minutes -= lunch_break_minutes.to_i
		
		[worked_minutes, 0].max
	end
	
	def hours_and_minutes
		mins = total_minutes_including_break
		
		return [hours.to_i, minutes.to_i] if mins.nil?
		
		[
			mins / 60,
			mins % 60
		]
	end
	
	# ------------------------------------------------------------
	# Datum
	# ------------------------------------------------------------
	
	def jahr
		date&.year
	end
	
	# ------------------------------------------------------------
	# Kilometer
	# ------------------------------------------------------------
	
	def kilometer_pauschale
		return 0 unless distance_km.present?
		
		year = date&.year
		
		rate =
			MileageRate.find_by(year: year)&.rate_per_km ||
			0.42
		
		(distance_km.to_d * rate.to_d).round(2)
	end
	
	def self.total_kilometer_cost_by_year(user)
		yearly_distances =
			where(user: user)
				.where.not(distance_km: nil)
				.group(Arel.sql("EXTRACT(YEAR FROM date)"))
				.order(Arel.sql("EXTRACT(YEAR FROM date) DESC"))
				.sum(:distance_km)
		
		yearly_distances.each_with_object({}) do |(year, km_sum), result|
			rate =
				MileageRate.find_by(year: year.to_i)&.rate_per_km ||
				0.42
			
			result[year.to_i] =
				(km_sum.to_d * rate.to_d).round(2)
		end
	end
	
	# ------------------------------------------------------------
	# Kosten
	# ------------------------------------------------------------
	
	def self.total_fortbildungskosten_by_year(user)
		where(user: user)
			.where.not(kosten: nil)
			.where(
				Entry.arel_table[:entry_art]
				.eq("Fortbildung")
				.or(
					Entry.arel_table[:zaehlt_als_fortbildung]
					.eq(true)
				)
			)
			.group(Arel.sql("DATE_PART('year', date)"))
			.order(Arel.sql("DATE_PART('year', date) DESC"))
			.pluck(
				Arel.sql("DATE_PART('year', date)::int"),
				Arel.sql("SUM(kosten)")
			)
			.to_h
	end
	
	def self.total_selbsterfahrungskosten_by_year(user)
		where(
			user: user,
			entry_art: [
				      "Selbsterfahrung",
				      "Gruppenselbsterfahrung"
			      ]
		)
			.where.not(kosten: nil)
			.group(Arel.sql("DATE_PART('year', date)"))
			.order(Arel.sql("DATE_PART('year', date) DESC"))
			.pluck(
				Arel.sql("DATE_PART('year', date)::int"),
				Arel.sql("SUM(kosten)")
			)
			.to_h
	end
	
	def self.total_supervision_by_year(user)
		where(
			user: user,
			entry_art: [
				      "Supervision",
				      "Peergruppensupervision",
				      "Einzel-/Kleingruppensupervision"
			      ]
		)
			.where.not(kosten: nil)
			.group(Arel.sql("DATE_PART('year', date)"))
			.order(Arel.sql("DATE_PART('year', date) DESC"))
			.pluck(
				Arel.sql("DATE_PART('year', date)::int"),
				Arel.sql("SUM(kosten)")
			)
			.to_h
	end
	
	# Der Name bleibt aus Kompatibilitätsgründen erhalten.
	#
	# Die Methode summiert weiterhin alle eingetragenen Kosten
	# eines Jahres, so wie dein bisheriger Code.
	def self.total_semesterkosten_by_year(user)
		where(user: user)
			.where.not(kosten: nil)
			.group(Arel.sql("DATE_PART('year', date)"))
			.order(Arel.sql("DATE_PART('year', date) DESC"))
			.pluck(
				Arel.sql("DATE_PART('year', date)::int"),
				Arel.sql("SUM(kosten)")
			)
			.to_h
	end
	
	def self.total_gesamtkosten_by_year(user)
		semester_by_year = total_semesterkosten_by_year(user)
		km_by_year       = total_kilometer_cost_by_year(user)
		
		years =
			(
				semester_by_year.keys +
					km_by_year.keys
			)
			.uniq
			.sort
			.reverse
		
		years.each_with_object({}) do |year, out|
			semester =
				(semester_by_year[year] || 0).to_d
			
			km =
				(km_by_year[year] || 0).to_d
			
			out[year] =
				(semester + km).round(2)
		end
	end
	
	# ------------------------------------------------------------
	# Mediation
	# ------------------------------------------------------------
	
	def mediation?
		praktikums_typ == "mediation"
	end
	
	def praesenzmodul?
		mediation? &&
			entry_art == "Präsenzmodul"
	end
	
	def mediation_supervision?
		mediation? &&
			entry_art == "Supervision"
	end
	
	def peergruppenarbeit?
		mediation? &&
			entry_art == "Peergruppenarbeit"
	end
	
	def fallarbeit?
		mediation? &&
			entry_art == "Fallarbeit"
	end
	
	def praxisseminar?
		mediation? &&
			entry_art == "Praxisseminare"
	end
	
	def literatur_und_selbststudium?
		mediation? &&
			entry_art == "Literatur- und Selbststudium"
	end
	
	# ------------------------------------------------------------
	# CSV
	# ------------------------------------------------------------
	
	def self.to_csv
		CSV.generate(
			headers: true,
			col_sep: ";"
		) do |csv|
			
			csv << [
				"Datum",
				"Stunden",
				"Minuten",
				"Typ",
				"Art",
				"Kilometer",
				"Beschreibung",
				"Kosten",
				"User"
			]
			
			all.each do |entry|
				csv << [
					entry.date,
					entry.hours,
					entry.minutes,
					entry.praktikums_typ,
					entry.entry_art,
					entry.distance_km,
					entry.beschreibung,
					entry.kosten,
					entry.user.email
				]
			end
		end
	end
	
	private
	
	# ------------------------------------------------------------
	# Alte Bezeichnungen automatisch migrieren
	# ------------------------------------------------------------
	
	def normalize_legacy_entry_art
		return if entry_art.blank?
		
		self.entry_art =
			LEGACY_ENTRY_ART_ALIASES.fetch(
				entry_art,
				entry_art
			)
	end
	
	# ------------------------------------------------------------
	# Zeit normalisieren
	# ------------------------------------------------------------
	
	def normalize_time
		if hours.to_i.zero? &&
		   minutes.to_i.zero? &&
		   start_time.present? &&
		   end_time.present?
			
			total_worked_minutes =
				total_minutes_including_break
			
			if total_worked_minutes
				self.hours =
					total_worked_minutes / 60
				
				self.minutes =
					total_worked_minutes % 60
			end
		else
			total =
				hours.to_i * 60 +
				minutes.to_i
			
			self.hours =
				total / 60
			
			self.minutes =
				total % 60
		end
	end
end