require 'sequel'

RESULTS_PER_PAGE = 50

def search(params)
  query = params[:q].strip
  offset = (params[:page] - 1) * RESULTS_PER_PAGE
  username = params[:username].strip
  from_date = params[:from_date].strip
  to_date = params[:to_date].strip

  errors = Array.new

  if from_date.empty?
    from_date = nil
  else
    if from_date.match(/\d{4}-\d{2}-\d{2}/)
      from_date = Date.parse(params[:from_date]) rescue errors << 'Invalid From Date'
    else
      errors << 'From Date must be in the format YYYY-MM-DD'
    end
  end

  if to_date.empty?
    to_date = nil
  else
    if to_date.match(/\d{4}-\d{2}-\d{2}/)
      to_date = Date.parse(params[:to_date]).next rescue errors << 'Invalid To Date'
    else
      errors << 'To Date must be in the format YYYY-MM-DD'
    end
  end

  if errors.empty? && !to_date.nil? && !from_date.nil? &&  to_date < from_date
    errors << 'To Date must be after From Date'
  end

  return {results: Array.new, errors: errors} unless errors.empty?

  results = case params[:type]
  when 'threads'
    sort =
      case params[:sort]
      when 'thread'
        'created_at DESC'
      when 'post'
        'last_post_created_at DESC'
      else
        'created_at DESC'
      end
    search_threads(query, username, from_date, to_date, sort, offset)
  when 'posts'
    search_posts(query, username, from_date, to_date, offset)
  else
    Array.new
  end

  {results: results, errors: errors}
end

def search_threads(query, username, from_date, to_date, sort, offset)
  DB[<<-SQL, query, username, username, from_date, from_date, to_date, to_date, offset]
    SELECT
      threads.*,
      count(*) OVER() AS full_count
    FROM threads
    WHERE
      to_tsvector(title) @@ plainto_tsquery(?)
      AND (LOWER(threads.creator) = LOWER(?) OR ? = '')
      AND (created_at >= ? OR ? IS NULL)
      AND (created_at <= ? OR ? IS NULL)
    ORDER BY #{sort}
    LIMIT #{RESULTS_PER_PAGE}
    OFFSET ?;
  SQL
end

def search_posts(query, username, from_date, to_date, offset)
  DB[<<-SQL, query, username, username, from_date, from_date, to_date, to_date, offset]
    SELECT
      posts.*,
      threads.title as thread_title,
      threads.remote_id as remote_thread_id,
      count(*) OVER() AS full_count
    FROM posts
    INNER JOIN threads on posts.thread_id = threads.id
    WHERE
      tsv @@ plainto_tsquery(?)
      AND ((LOWER(posts.creator) = LOWER(?)) OR (? = ''))
      AND (posts.created_at >= ? OR ? IS NULL)
      AND (posts.created_at <= ? OR ? IS NULL)
    ORDER BY posts.created_at DESC
    LIMIT #{RESULTS_PER_PAGE}
    OFFSET ?;
  SQL
end