require 'chronic'
require 'sexp_processor'
require 'ruby_parser'
require 'json'
require 'hirb'
require 'fileutils'

$LOAD_PATH.unshift(File.dirname(__FILE__))
require 'source_control'
require 'git_analyzer'
require 'svn_analyzer'
require 'hg_analyzer'
require 'bzr_analyzer'
require 'location_mapping'
require 'churn_history'

module Churn

  # The work horse of the the churn library. This class takes user input, determins the SCM the user is using. It then determines changes
  # made during this revision. Finally it reads all the changes from previous revisions and displays human readable output to the command
  # line. It can also ouput a yaml format readable by other tools such as metric_fu and Caliper.
  class ChurnCalculator

    # intialized the churn calculator object
    def initialize(options={})
      start_date = options.fetch(:start_date) { '3 months ago' }
      @minimum_churn_count = options.fetch(:minimum_churn_count) { 5 }
      @ignore_files     = (options.fetch(:ignore_files){ "" }).split(',').map(&:strip)
      @ignore_files << '/dev/null'
      @source_control   = set_source_control(start_date)
      @changes          = {}
      @revision_changes = {}
      @class_changes    = {}
      @method_changes   = {}
    end

    # prepares the data for the given project to be reported.
    # reads git/svn logs analyzes the output, generates a report and either formats as a nice string or returns hash.
    # @param [Bolean] format to return the data, true for string or false for hash
    # @return [Object] returns either a pretty string or a hash representing the chrun of the project
    def report(print = true)
      self.emit
      self.analyze
      print ? self.to_s : self.to_h
    end

    # Emits various data from source control to be analyses later... Currently this is broken up like this as a throwback to metric_fu
    def emit
      @changes   = parse_log_for_changes.reject {|file, change_count| change_count < @minimum_churn_count || @ignore_files.include?(file) }
      @revisions = parse_log_for_revision_changes
    end

    # Analyze the source control data, filter, sort, and find more information on the editted files
    def analyze
      @changes = sort_changes(@changes)
      @changes = @changes.map {|file_path, times_changed| {:file_path => file_path, :times_changed => times_changed }}

      calculate_revision_changes

      @method_changes = sort_changes(@method_changes)
      @method_changes = @method_changes.map {|method, times_changed| {'method' => method, 'times_changed' => times_changed }}
      @class_changes  = sort_changes(@class_changes)
      @class_changes  = @class_changes.map {|klass, times_changed| {'klass' => klass, 'times_changed' => times_changed }}
    end

    # collect all the data into a single hash data structure.
    def to_h
      hash                        = {:churn => {:changes => @changes}}
      hash[:churn][:class_churn]  = @class_changes
      hash[:churn][:method_churn] = @method_changes
      #detail the most recent changes made this revision
      first_revision         = @revisions.first
      first_revision_changes = @revision_changes[first_revision]
      if first_revision_changes
        changes = first_revision_changes
        hash[:churn][:changed_files]   = changes[:files]
        hash[:churn][:changed_classes] = changes[:classes]
        hash[:churn][:changed_methods] = changes[:methods]
      end
      #TODO crappy place to do this but save hash to revision file but while entirely under metric_fu only choice
      ChurnHistory.store_revision_history(first_revision, hash)
      hash
    end

    # Pretty print the data as a string for the user
    def to_s
      hash   = to_h[:churn]
      result = seperator
      result +="* Revision Changes \n"
      result += seperator
      result += "Files: \n"
      result += display_array(hash[:changed_files], :fields=>[:to_str], :headers=>{:to_str=>'file'})
      result += "\nClasses: \n"
      result += display_array(hash[:changed_classes])
      result += "\nMethods: \n"
      result += display_array(hash[:changed_methods]) + "\n"
      result += seperator
      result +="* Project Churn \n"
      result += seperator
      result += "Files: \n"
      result += display_array(hash[:changes])
      result += "\nClasses: \n"
      class_churn = collect_items(hash[:class_churn], 'klass')
      result += display_array(class_churn)
      result += "\nMethods: \n"
      method_churn = collect_items(hash[:method_churn], 'method')
      result += display_array(method_churn)
    end

    private

    def collect_items(collection, match)
      collection.map {|item| (item.delete(match) || {}).merge(item) }
    end

    def sort_changes(changes)
      changes.to_a.sort! {|first,second| second[1] <=> first[1]}
    end

    def filters
      /.*\.rb/
    end

    def display_array(array, options={})
      array ? Hirb::Helpers::AutoTable.render(array, options.merge(:description=>false)) + "\n" : ''
    end

    def seperator
      "*"*70+"\n"
    end

    def self.git?
      system("git branch")
    end

    def self.hg?
      system("hg branch")
    end

    def self.bzr?
        system("bzr nick")
    end

    def set_source_control(start_date)
      if self.class.git?
        GitAnalyzer.new(start_date)
      elsif self.class.hg?
        HgAnalyzer.new(start_date)
      elsif self.class.bzr?
        BzrAnalyzer.new(start_date)
      elsif File.exist?(".svn")
        SvnAnalyzer.new(start_date)
      else
        raise "Churning requires a bazaar, git, mercurial, or subversion repo"
      end
    end

    def calculate_revision_changes
      @revisions.each do |revision|
        if revision == @revisions.first
          #can't iterate through all the changes and tally them up
          #it only has the current files not the files at the time of the revision
          #parsing requires the files
          changed_files, changed_classes, changed_methods = calculate_revision_data(revision)
        else
          changed_files, changed_classes, changed_methods = ChurnHistory.load_revision_data(revision)
        end
        calculate_changes!(changed_methods, @method_changes) if changed_methods
        calculate_changes!(changed_classes, @class_changes) if changed_classes

        @revision_changes[revision] = { :files => changed_files, :classes => changed_classes, :methods => changed_methods }
      end
    end

    def calculate_revision_data(revision)
      changed_files   = parse_logs_for_updated_files(revision, @revisions)

      changed_classes = []
      changed_methods = []
      changed_files.each do |file_changes|
        if file_changes.first.match(filters)
          classes, methods = get_changes(file_changes)
          changed_classes += classes
          changed_methods += methods
        end
      end
      changed_files   = changed_files.map { |file, lines| file }
      [changed_files, changed_classes, changed_methods]
    end

    def calculate_changes!(changed_objs, total_changes)
      if changed_objs
        changed_objs.each do |change|
          total_changes.include?(change) ? total_changes[change] = total_changes[change]+1 : total_changes[change] = 1
        end
      end
      total_changes
    end

    def get_changes(change)
      file = change.first
      breakdown = LocationMapping.new
      breakdown.get_info(file)
      changes = change.last
      classes = changes_for_type(changes, breakdown.klasses_collection)
      methods = changes_for_type(changes, breakdown.methods_collection)
      classes = classes.map{ |klass| {'file' => file, 'klass' => klass} }
      methods = methods.map{ |method| {'file' => file, 'klass' => get_klass_for(method), 'method' => method} }
      [classes, methods]
    rescue => error
      [[],[]]
    end

    def get_klass_for(method)
      method.gsub(/(#|\.).*/,'')
    end

    def changes_for_type(changes, item_collection)
      changed_items  = []
      item_collection.each_pair do |item, item_lines|
        item_lines = item_lines[0].to_a
        changes.each do |change_range|
          item_lines.each do |line|
            changed_items << item if change_range.include?(line) && !changed_items.include?(item)
          end
        end
      end
      changed_items
    end

    def parse_log_for_changes
      changes = {}

      logs = @source_control.get_logs
      logs.each do |line|
        changes[line] ? changes[line] += 1 : changes[line] = 1
      end
      changes
    end

    def parse_log_for_revision_changes
      return [] unless @source_control.respond_to?(:get_revisions)
      @source_control.get_revisions
    end

    def parse_logs_for_updated_files(revision, revisions)
      #TODO SVN doesn't support this
      return {} unless @source_control.respond_to?(:get_updated_files_change_info)
      files = @source_control.get_updated_files_change_info(revision, revisions)
      files.select{ |file, value| !@ignore_files.include?(file) }
    end

  end

end