defmodule AprsWeb.Helpers.AprsSymbols do
  @moduledoc """
  Helper functions for working with APRS symbols.

  APRS symbols are organized in sprite sheets:
  - Primary table (symbol_table_id = "/"): aprs-symbols-24-0.png
  - Secondary table (symbol_table_id = "\\"): aprs-symbols-24-1.png
  - Overlay characters: aprs-symbols-24-2.png

  Each sprite sheet is a 16x6 grid (96 symbols total).
  Symbol positioning is based on ASCII code of the symbol_code.
  """

  @symbol_descriptions %{
    {"/", "!"} => "Police/Sheriff",
    {"/", "\""} => "Reserved",
    {"/", "#"} => "Digipeater",
    {"/", "$"} => "Phone",
    {"/", "%"} => "DX Cluster",
    {"/", "&"} => "HF Gateway",
    {"/", "'"} => "Small Aircraft",
    {"/", "("} => "Mobile Satellite Station",
    {"/", ")"} => "Wheelchair",
    {"/", "*"} => "Snowmobile",
    {"/", "+"} => "Red Cross",
    {"/", ","} => "Boy Scout",
    {"/", "-"} => "House",
    {"/", "."} => "X",
    {"/", "/"} => "Position",
    {"/", "0"} => "Circle",
    {"/", "1"} => "Circle",
    {"/", "2"} => "Circle",
    {"/", "3"} => "Circle",
    {"/", "4"} => "Circle",
    {"/", "5"} => "Circle",
    {"/", "6"} => "Circle",
    {"/", "7"} => "Circle",
    {"/", "8"} => "Circle",
    {"/", "9"} => "Circle",
    {"/", ":"} => "Fire Department",
    {"/", ";"} => "Campground",
    {"/", "<"} => "Motorcycle",
    {"/", "="} => "Rail Engine",
    {"/", ">"} => "Car",
    {"/", "?"} => "File Server",
    {"/", "@"} => "HC Future",
    {"/", "A"} => "Aid Station",
    {"/", "B"} => "BBS",
    {"/", "C"} => "Canoe",
    {"/", "D"} => "Reserved",
    {"/", "E"} => "Eyeball",
    {"/", "F"} => "Tractor",
    {"/", "G"} => "Grid Square",
    {"/", "H"} => "Hotel",
    {"/", "I"} => "TCP/IP",
    {"/", "J"} => "Phone",
    {"/", "K"} => "School",
    {"/", "L"} => "PC User",
    {"/", "M"} => "MacAPRS",
    {"/", "N"} => "NTS Station",
    {"/", "O"} => "Balloon",
    {"/", "P"} => "Police",
    {"/", "Q"} => "TBD",
    {"/", "R"} => "Recreational Vehicle",
    {"/", "S"} => "Shuttle",
    {"/", "T"} => "SSTV",
    {"/", "U"} => "Bus",
    {"/", "V"} => "ATV",
    {"/", "W"} => "National Weather Service",
    {"/", "X"} => "Helo",
    {"/", "Y"} => "Yacht",
    {"/", "Z"} => "WinAPRS",
    {"/", "["} => "Jogger",
    {"/", "\\"} => "Triangle",
    {"/", "]"} => "PBBS",
    {"/", "^"} => "Aircraft",
    {"/", "_"} => "Weather Station",
    {"/", "`"} => "Dish Antenna",
    {"/", "a"} => "Ambulance",
    {"/", "b"} => "Bike",
    {"/", "c"} => "Incident Command Post",
    {"/", "d"} => "Fire Depts",
    {"/", "e"} => "Horse",
    {"/", "f"} => "Fire Truck",
    {"/", "g"} => "Glider",
    {"/", "h"} => "Hospital",
    {"/", "i"} => "IOTA",
    {"/", "j"} => "Jeep",
    {"/", "k"} => "Truck",
    {"/", "l"} => "Laptop",
    {"/", "m"} => "Mic-E",
    {"/", "n"} => "Node",
    {"/", "o"} => "EOC",
    {"/", "p"} => "Dog",
    {"/", "q"} => "Grid",
    {"/", "r"} => "Repeater",
    {"/", "s"} => "Ship",
    {"/", "t"} => "Truck Stop",
    {"/", "u"} => "Truck",
    {"/", "v"} => "Van",
    {"/", "w"} => "Water Station",
    {"/", "x"} => "X-APRS",
    {"/", "y"} => "Yagi",
    {"/", "z"} => "Shelter",
    {"\\", "!"} => "Emergency",
    {"\\", "\""} => "Reserved",
    {"\\", "#"} => "Digipeater",
    {"\\", "$"} => "Bank",
    {"\\", "%"} => "Reserved",
    {"\\", "&"} => "Reserved",
    {"\\", "'"} => "Reserved",
    {"\\", "("} => "Reserved",
    {"\\", ")"} => "Reserved",
    {"\\", "*"} => "Reserved",
    {"\\", "+"} => "Reserved",
    {"\\", ","} => "Reserved",
    {"\\", "-"} => "Reserved",
    {"\\", "."} => "Reserved",
    {"\\", "/"} => "Triangle",
    {"\\", "0"} => "Reserved",
    {"\\", "1"} => "Reserved",
    {"\\", "2"} => "Reserved",
    {"\\", "3"} => "Reserved",
    {"\\", "4"} => "Reserved",
    {"\\", "5"} => "Reserved",
    {"\\", "6"} => "Reserved",
    {"\\", "7"} => "Reserved",
    {"\\", "8"} => "Reserved",
    {"\\", "9"} => "Reserved",
    {"\\", ":"} => "Reserved",
    {"\\", ";"} => "Reserved",
    {"\\", "<"} => "Reserved",
    {"\\", "="} => "Reserved",
    {"\\", ">"} => "Car (alternate)",
    {"\\", "?"} => "Reserved",
    {"\\", "@"} => "Reserved",
    {"\\", "A"} => "Reserved",
    {"\\", "B"} => "Reserved",
    {"\\", "C"} => "Reserved",
    {"\\", "D"} => "Reserved",
    {"\\", "E"} => "Reserved",
    {"\\", "F"} => "Reserved",
    {"\\", "G"} => "Reserved",
    {"\\", "H"} => "Reserved",
    {"\\", "I"} => "Reserved",
    {"\\", "J"} => "Reserved",
    {"\\", "K"} => "Reserved",
    {"\\", "L"} => "Reserved",
    {"\\", "M"} => "Reserved",
    {"\\", "N"} => "Reserved",
    {"\\", "O"} => "Reserved",
    {"\\", "P"} => "Reserved",
    {"\\", "Q"} => "Reserved",
    {"\\", "R"} => "Reserved",
    {"\\", "S"} => "Reserved",
    {"\\", "T"} => "Reserved",
    {"\\", "U"} => "Reserved",
    {"\\", "V"} => "Reserved",
    {"\\", "W"} => "Reserved",
    {"\\", "X"} => "Reserved",
    {"\\", "Y"} => "Reserved",
    {"\\", "Z"} => "Reserved",
    {"\\", "["} => "Reserved",
    {"\\", "\\"} => "Reserved",
    {"\\", "]"} => "Reserved",
    {"\\", "^"} => "Reserved",
    {"\\", "_"} => "Reserved",
    {"\\", "`"} => "Reserved",
    {"\\", "a"} => "Reserved",
    {"\\", "b"} => "Reserved",
    {"\\", "c"} => "Reserved",
    {"\\", "d"} => "Reserved",
    {"\\", "e"} => "Reserved",
    {"\\", "f"} => "Reserved",
    {"\\", "g"} => "Reserved",
    {"\\", "h"} => "Reserved",
    {"\\", "i"} => "Reserved",
    {"\\", "j"} => "Reserved",
    {"\\", "k"} => "Reserved",
    {"\\", "l"} => "Reserved",
    {"\\", "m"} => "Reserved",
    {"\\", "n"} => "Reserved",
    {"\\", "o"} => "Reserved",
    {"\\", "p"} => "Reserved",
    {"\\", "q"} => "Reserved",
    {"\\", "r"} => "Reserved",
    {"\\", "s"} => "Reserved"
  }

  @doc """
  Get the sprite sheet filename for a given symbol table ID.

  ## Examples

      iex> AprsWeb.Helpers.AprsSymbols.get_sprite_filename("/")
      "aprs-symbols-24-0.png"

      iex> AprsWeb.Helpers.AprsSymbols.get_sprite_filename("\\")
      "aprs-symbols-24-1.png"
  """
  @spec get_sprite_filename(String.t()) :: String.t()
  def get_sprite_filename(symbol_table_id) do
    case symbol_table_id do
      "/" -> "aprs-symbols-24-0.png"
      "\\" -> "aprs-symbols-24-1.png"
      # Default to primary table
      _ -> "aprs-symbols-24-0.png"
    end
  end

  @doc """
  Get the high-resolution sprite sheet filename for retina displays.
  """
  @spec get_sprite_filename_2x(String.t()) :: String.t()
  def get_sprite_filename_2x(symbol_table_id) do
    case symbol_table_id do
      "/" -> "aprs-symbols-24-0@2x.png"
      "\\" -> "aprs-symbols-24-1@2x.png"
      _ -> "aprs-symbols-24-0@2x.png"
    end
  end

  @doc """
  Calculate the CSS background position for a symbol in the sprite sheet.

  The sprite sheet is organized as a 16x6 grid.
  ASCII codes 32-127 map to positions 0-95.

  ## Examples

      iex> AprsWeb.Helpers.AprsSymbols.get_symbol_position(">")
      {-1440, 0}  # ASCII 62, position 30 -> column 14, row 1

      iex> AprsWeb.Helpers.AprsSymbols.get_symbol_position("!")
      {-216, 0}   # ASCII 33, position 1 -> column 1, row 0
  """
  @spec get_symbol_position(String.t() | integer()) :: {integer(), integer()}
  def get_symbol_position(symbol_code) when is_binary(symbol_code) do
    # Get first character if string
    char_code = symbol_code |> String.first() |> String.to_charlist() |> List.first()
    get_symbol_position_by_ascii(char_code)
  end

  def get_symbol_position(symbol_code) when is_integer(symbol_code) do
    get_symbol_position_by_ascii(symbol_code)
  end

  defp get_symbol_position_by_ascii(ascii_code) do
    # ASCII 32 (space) is position 0, ASCII 127 (DEL) is position 95
    position = ascii_code - 32

    # Clamp position to valid range 0-95
    position = max(0, min(95, position))

    # Calculate row and column (16 symbols per row)
    col = rem(position, 16)
    row = div(position, 16)

    # Each symbol is 24x24 pixels
    x = -col * 24
    y = -row * 24

    {x, y}
  end

  @doc """
  Generate CSS style for displaying an APRS symbol using sprite positioning.

  ## Examples

      iex> AprsWeb.Helpers.AprsSymbols.symbol_css_style("/", ">")
      "background-image: url('/aprs-symbols/aprs-symbols-24-0.png'); background-position: -1440px 0px; width: 24px; height: 24px;"
  """
  @spec symbol_css_style(String.t(), String.t() | integer()) :: String.t()
  def symbol_css_style(symbol_table_id, symbol_code) do
    sprite_file = get_sprite_filename(symbol_table_id)
    {x, y} = get_symbol_position(symbol_code)

    "background-image: url('/aprs-symbols/#{sprite_file}'); " <>
      "background-position: #{x}px #{y}px; " <>
      "width: 24px; height: 24px; " <>
      "background-repeat: no-repeat;"
  end

  @doc """
  Generate HTML for an APRS symbol with proper sprite positioning.
  """
  @spec symbol_html(String.t(), String.t() | integer(), keyword()) :: {:safe, String.t()}
  def symbol_html(symbol_table_id, symbol_code, opts \\ []) do
    css_class = Keyword.get(opts, :class, "aprs-symbol")
    extra_style = Keyword.get(opts, :style, "")

    base_style = symbol_css_style(symbol_table_id, symbol_code)
    full_style = if extra_style == "", do: base_style, else: base_style <> " " <> extra_style

    Phoenix.HTML.raw(~s(<div class="#{css_class}" style="#{full_style}"></div>))
  end

  @doc """
  Get a data URL for the symbol that can be used in JavaScript/Leaflet.
  This creates a small canvas with just the symbol extracted from the sprite.
  """
  @spec get_symbol_data_attributes(String.t(), String.t() | integer()) :: map()
  def get_symbol_data_attributes(symbol_table_id, symbol_code) do
    sprite_file = get_sprite_filename(symbol_table_id)
    sprite_file_2x = get_sprite_filename_2x(symbol_table_id)
    {x, y} = get_symbol_position(symbol_code)

    %{
      "data-sprite" => sprite_file,
      "data-sprite-2x" => sprite_file_2x,
      "data-pos-x" => x,
      "data-pos-y" => y,
      "data-symbol-table" => symbol_table_id,
      "data-symbol-code" => symbol_code
    }
  end

  @doc """
  Get the default symbol for unknown or invalid symbols.
  """
  @spec default_symbol() :: {String.t(), String.t()}
  def default_symbol do
    # Car icon as default
    {"/", ">"}
  end

  @doc """
  Validate if a symbol table ID and code combination is valid.
  """
  @spec valid_symbol?(any(), any()) :: boolean()
  def valid_symbol?(symbol_table_id, symbol_code) do
    case {symbol_table_id, symbol_code} do
      {table, code} when table in ["/", "\\"] and is_binary(code) and byte_size(code) > 0 ->
        char_code = code |> String.first() |> String.to_charlist() |> List.first()
        char_code >= 32 and char_code <= 127

      _ ->
        false
    end
  end

  @doc """
  Get a human-readable description for common APRS symbols.
  This is a subset of common symbols - for a complete list, you'd want to
  reference the official APRS symbol specification.
  """
  @spec symbol_description(String.t(), String.t()) :: String.t()
  def symbol_description(symbol_table_id, symbol_code) do
    Map.get(@symbol_descriptions, {symbol_table_id, symbol_code}, "Unknown symbol")
  end
end