module BomRadarImage

# File lib/bom_radar_image.rb, line 108
def char_for_background(index)
  BACKGROUND_META.fetch(index) { BACKGROUND_META[2] }[:char]
end

# File lib/bom_radar_image.rb, line 112
def char_for_index(index, center: false)
  return BomRadarConfig::CENTER_CHAR if center

  meta_for(index)[:char]
end

# File lib/bom_radar_image.rb, line 118
def char_for_merged(index, center: false)
  return BomRadarConfig::CENTER_CHAR if center

  meta_for_merged(index)[:char]
end

# File lib/bom_radar_image.rb, line 160
def colorize_line(line, grid: nil, center: nil, row: nil, merged: false)
  return "" if line.empty?

  runs = []
  line.each_char.with_index do |char, col_index|
    style_key = if char == BomRadarConfig::CENTER_CHAR
                  :center
                elsif grid && row
                  merged ? style_for_merged(grid[row][col_index]) : style_for(grid[row][col_index])
                else
                  style_for_char(char)
                end
    style = CELL_STYLES[style_key]
    if runs.empty? || runs.last[:style] != style
      runs << { style: style, chars: char }
    else
      runs.last[:chars] << char
    end
  end

  runs.map { |run| "#{run[:style]}#{run[:chars]}#{IRC_RESET}" }.join
end

# File lib/bom_radar_image.rb, line 198
def colorize_lines(lines, grid: nil, center: nil, merged: false)
  lines.each_with_index.map do |line, row|
    colorize_line(line, grid: grid, center: center, row: row, merged: merged)
  end
end

# File lib/bom_radar_image.rb, line 63
def decode(bytes)
  decoded = BomRadarPng.decode_indices(bytes)
  { width: decoded[:width], height: decoded[:height], grid: decoded[:grid] }
end

# File lib/bom_radar_image.rb, line 128
def display_intensity(index)
  return nil if index.to_i < BomRadarConfig::RAIN_MIN_INDEX

  label = intensity_label(index)
  return label if label

  nil
end

# File lib/bom_radar_image.rb, line 86
def dominant_index(source, rows, cols)
  counts = Hash.new(0)
  rows.each do |row|
    cols.each do |col|
      idx = source[row][col]
      counts[idx] += 1
    end
  end
  counts.max_by { |index, count| [count, -index] }&.first || 0
end

# File lib/bom_radar_image.rb, line 68
def downsample(grid_data, width: BomRadarConfig::MAP_WIDTH, height: BomRadarConfig::MAP_HEIGHT)
  source = grid_data[:grid]
  src_h = grid_data[:height]
  src_w = grid_data[:width]
  block_h = src_h.to_f / height
  block_w = src_w.to_f / width

  Array.new(height) do |row|
    Array.new(width) do |col|
      y0 = (row * block_h).floor
      y1 = [((row + 1) * block_h).ceil - 1, src_h - 1].min
      x0 = (col * block_w).floor
      x1 = [((col + 1) * block_w).ceil - 1, src_w - 1].min
      dominant_index(source, y0..y1, x0..x1)
    end
  end
end

# File lib/bom_radar_image.rb, line 149
def grid_to_chars(grid, center: nil)
  height = grid.length
  width = grid.first.length
  grid.map.with_index do |row, row_index|
    row.map.with_index do |index, col_index|
      is_center = center && center[0] == row_index && center[1] == col_index
      char_for_index(index, center: is_center)
    end.join
  end
end

# File lib/bom_radar_image.rb, line 124
def intensity_label(index)
  meta_for(index)[:label]
end

# File lib/bom_radar_image.rb, line 97
def meta_for(index)
  INDEX_META[index] || INDEX_META[0]
end

# File lib/bom_radar_image.rb, line 101
def meta_for_merged(index)
  value = index.to_i
  return BACKGROUND_META[value] if value < BomRadarConfig::RAIN_MIN_INDEX

  meta_for(value)
end

# File lib/bom_radar_image.rb, line 137
def style_for(index, center: false)
  return :center if center

  meta_for(index)[:style]
end

# File lib/bom_radar_image.rb, line 183
def style_for_char(char)
  case char
  when "#" then :border
  when "." then :land
  when "~" then :sea
  when "|" then :coast
  when ":" then :light
  when "o" then :moderate
  when "O" then :heavy
  when "@" then :intense
  when "+" then :center
  else :clear
  end
end

# File lib/bom_radar_image.rb, line 143
def style_for_merged(index, center: false)
  return :center if center

  meta_for_merged(index)[:style]
end