require 'jared/screen'

module JarEd
  class FileView
    attr_accessor :pane

    def initialize(buffer)
      @buffer = buffer
      @row_offset = 0
      @cursor_row = 0
      @cursor_column = 0
    end

    # @todo Make this method not awful.
    def to_screen
      Screen.new(
        cursor_column: screen_cursor_column,
        cursor_row: screen_cursor_row,
        lines: screen_lines
      )
    end

    def send_input(input)
      case input
      when "h"
        update_cursor(column: cursor_column - 1)
      when "j"
        update_cursor(row: cursor_row + 1)
      when "k"
        update_cursor(row: cursor_row - 1)
      when "l"
        update_cursor(column: cursor_column + 1)
      end
    end

    private

    attr_reader :buffer

    attr_accessor :cursor_row,
                  :cursor_column,
                  :row_offset

    def width
      pane.width
    end

    def height
      pane.height
    end

    def update_cursor(row: cursor_row, column: cursor_column)
      row = [0, row].max
      row = [row, buffer.lines.length - 1].min
      @cursor_row = row

      column = [0, column].max
      column = [column, current_line.raw_text.length - 1].min
      @cursor_column = column

      if row < row_offset
        self.row_offset = row
      end

      # FIXME: Can probably do this more efficiently.
      # FIXME: This only fits the first row worth of the current line on the
      # screen. The desired behaviour is that all the rows of the current line
      # are fit on in this scenario.
      while screen_cursor_row >= height
        self.row_offset = row_offset + 1
      end
    end

    def current_line
      buffer.lines[cursor_row]
    end

    def screen_cursor_column
      if cursor_column < width
        cursor_column
      else
        cursor_column % width
      end
    end

    def screen_cursor_row
      buffer.lines.slice(row_offset, buffer.lines.length - 1).reduce(0) do |acc, line|
        if line == current_line
          if cursor_column < width
            break acc
          else
            break acc + cursor_column / width
          end
        else
          acc + line.wrap(width: width).length
        end
      end
    end

    def screen_lines
      buffer.wrapped_lines(
        offset: row_offset,
        width: width,
        height: height
      )
    end
  end
end