defmodule MoundHunters.Repo do
  @moduledoc """
  Mnesia database helpers for tiles and geometries.
  """

  require Logger

  # Tile statuses
  @type tile_status :: :processing | :ready | :error

  @doc """
  Get a tile by its ID.
  Returns {:ok, tile} or {:error, :not_found}
  """
  def get_tile(id) do
    case :mnesia.transaction(fn ->
           :mnesia.read(:tiles, id)
         end) do
      {:atomic, [tile]} ->
        {:ok, tile_to_map(tile)}

      {:atomic, []} ->
        {:error, :not_found}

      {:aborted, reason} ->
        Logger.error("Failed to read tile #{id}: #{inspect(reason)}")
        {:error, :database_error}
    end
  end

  @doc """
  Get a tile that contains the given lat/lng coordinates.
  Returns {:ok, tile} or {:error, :not_found}

  If multiple tiles contain the point, returns the first match.
  """
  def get_tile_at_coords(lat, lng) do
    match_spec = [
      {{:tiles, :"$1", :"$2", :"$3", :"$4", :"$5", :"$6", :"$7", :"$8", :"$9", :"$10", :"$11"},
       [
         {:andalso, {:"=<", :"$2", lat}, {:"=<", lat, :"$3"}},
         {:andalso, {:"=<", :"$4", lng}, {:"=<", lng, :"$5"}}
       ], [:"$_"]}
    ]

    case :mnesia.transaction(fn ->
           :mnesia.select(:tiles, match_spec)
         end) do
      {:atomic, [tile | _]} ->
        {:ok, tile_to_map(tile)}

      {:atomic, []} ->
        {:error, :not_found}

      {:aborted, reason} ->
        Logger.error("Failed to query tiles at #{lat}, #{lng}: #{inspect(reason)}")
        {:error, :database_error}
    end
  end

  @doc """
  Insert or update a tile record.
  """
  def upsert_tile(attrs) do
    tile_id = Map.fetch!(attrs, :id)
    now = System.system_time(:second)

    tile_record =
      {:tiles, tile_id, Map.get(attrs, :min_lat), Map.get(attrs, :max_lat),
       Map.get(attrs, :min_lng), Map.get(attrs, :max_lng), Map.get(attrs, :status),
       Map.get(attrs, :error_message), Map.get(attrs, :jpg_available, false),
       Map.get(attrs, :png_available, false), Map.get(attrs, :created_at, now), now}

    case :mnesia.transaction(fn ->
           :mnesia.write(tile_record)
         end) do
      {:atomic, :ok} -> {:ok, tile_to_map(tile_record)}
      {:aborted, reason} -> {:error, reason}
    end
  end

  @doc """
  Get a shared geometry by ID.
  """
  def get_geometry(geometry_id) do
    case :mnesia.transaction(fn ->
           :mnesia.read(:geometries, geometry_id)
         end) do
      {:atomic, [geometry]} -> {:ok, geometry_to_map(geometry)}
      {:atomic, []} -> {:error, :not_found}
      {:aborted, reason} -> {:error, reason}
    end
  end

  @doc """
  Create a new shared geometry.
  """
  def create_geometry(geojson) do
    geometry_id = generate_id()
    now = System.system_time(:second)

    geometry_record = {:geometries, geometry_id, geojson, now}

    case :mnesia.transaction(fn ->
           :mnesia.write(geometry_record)
         end) do
      {:atomic, :ok} -> {:ok, %{id: geometry_id}}
      {:aborted, reason} -> {:error, reason}
    end
  end

  # Convert Mnesia tile record to map
  defp tile_to_map(
         {:tiles, id, min_lat, max_lat, min_lng, max_lng, status, error_message, jpg_available,
          png_available, created_at, updated_at}
       ) do
    %{
      id: id,
      min_lat: min_lat,
      max_lat: max_lat,
      min_lng: min_lng,
      max_lng: max_lng,
      status: status,
      error_message: error_message,
      jpg_available: jpg_available,
      png_available: png_available,
      created_at: created_at,
      updated_at: updated_at
    }
  end

  # Convert Mnesia geometry record to map
  defp geometry_to_map({:geometries, id, geojson, created_at}) do
    %{
      id: id,
      geojson: geojson,
      created_at: created_at
    }
  end

  @doc """
  Repopulate tiles table from .mound files in the configured directory.
  Skips tiles that already exist in the database.
  Returns {success_count, skip_count, error_count}.
  """
  def repopulate_from_mounds do
    tile_dir = Application.get_env(:mound_hunters, :tile_output_dir)
    mound_dir = Path.join(tile_dir, "MOUND")

    Logger.info("Scanning for .mound files in: #{mound_dir}")

    case File.ls(mound_dir) do
      {:ok, files} ->
        results =
          files
          |> Enum.filter(&String.ends_with?(&1, ".mound"))
          |> Enum.map(fn filename ->
            # Extract tile_id from filename (e.g., "BS18921654.mound" -> "BS18921654")
            tile_id = Path.rootname(filename)
            full_path = Path.join(mound_dir, filename)

            process_mound_file(tile_id, full_path)
          end)

        successes = Enum.count(results, &(&1 == :ok))
        skips = Enum.count(results, &(&1 == :skipped))
        errors = Enum.count(results, &match?({:error, _}, &1))

        Logger.info(
          "Repopulation complete: #{successes} inserted, #{skips} skipped, #{errors} errors"
        )

        {successes, skips, errors}

      {:error, reason} ->
        Logger.error("Failed to list directory #{mound_dir}: #{inspect(reason)}")
        {:error, reason}
    end
  end

  @doc """
  Scan tile directories and update jpg_available and png_available flags.
  Returns {updated_count, not_found_count}.
  """
  def update_tile_availability do
    tile_dir = Application.get_env(:mound_hunters, :tile_output_dir)
    mound_dir = Path.join(tile_dir, "MOUND")
    png_dir = Path.join(tile_dir, "PNG")
    jpg_dir = Path.join(tile_dir, "JPG")

    Logger.info("Scanning tile availability in: #{mound_dir}")

    # Get all tile IDs from database
    case :mnesia.transaction(fn ->
           :mnesia.match_object({:tiles, :_, :_, :_, :_, :_, :_, :_, :_, :_, :_, :_})
         end) do
      {:atomic, tiles} ->
        results =
          tiles
          |> Enum.map(fn tile_record ->
            tile = tile_to_map(tile_record)
            tile_id = tile.id

            jpg_path = Path.join(jpg_dir, "#{tile_id}.jpg")
            png_path = Path.join(png_dir, "#{tile_id}.png")

            jpg_available = File.exists?(jpg_path)
            png_available = File.exists?(png_path)

            # Only update if availability changed
            if jpg_available != tile.jpg_available or png_available != tile.png_available do
              attrs = %{
                id: tile_id,
                min_lat: tile.min_lat,
                max_lat: tile.max_lat,
                min_lng: tile.min_lng,
                max_lng: tile.max_lng,
                status: tile.status,
                error_message: tile.error_message,
                jpg_available: jpg_available,
                png_available: png_available,
                created_at: tile.created_at
              }

              case upsert_tile(attrs) do
                {:ok, _} ->
                  Logger.debug("Updated #{tile_id}: jpg=#{jpg_available}, png=#{png_available}")

                  :updated

                {:error, reason} ->
                  Logger.error("Failed to update #{tile_id}: #{inspect(reason)}")
                  {:error, reason}
              end
            else
              :unchanged
            end
          end)

        updated = Enum.count(results, &(&1 == :updated))
        unchanged = Enum.count(results, &(&1 == :unchanged))
        errors = Enum.count(results, &match?({:error, _}, &1))

        Logger.info(
          "Availability scan complete: #{updated} updated, #{unchanged} unchanged, #{errors} errors"
        )

        {updated, unchanged, errors}

      {:aborted, reason} ->
        Logger.error("Failed to read tiles: #{inspect(reason)}")
        {:error, reason}
    end
  end

  defp process_mound_file(tile_id, file_path) do
    # Check if tile already exists
    case get_tile(tile_id) do
      {:ok, _existing} ->
        Logger.debug("Skipping existing tile: #{tile_id}")
        :skipped

      {:error, :not_found} ->
        # Parse header and insert
        case MoundHunters.MoundParser.parse_header(file_path) do
          {:ok, header} ->
            # Convert Web Mercator coordinates to lat/lng
            bounds =
              MoundHunters.MoundParser.bounds_web_mercator_to_latlon(%{
                min_x: header.min_x,
                max_x: header.max_x,
                min_y: header.min_y,
                max_y: header.max_y
              })

            # Check for jpg and png availability
            tile_dir = Application.get_env(:mound_hunters, :tile_output_dir)
            mound_dir = Path.join(tile_dir, "MOUND")
            jpg_available = File.exists?(Path.join(mound_dir, "#{tile_id}.jpg"))
            png_available = File.exists?(Path.join(mound_dir, "#{tile_id}.png"))

            attrs = %{
              id: tile_id,
              min_lat: bounds.min_lat,
              max_lat: bounds.max_lat,
              min_lng: bounds.min_lng,
              max_lng: bounds.max_lng,
              status: :ready,
              error_message: nil,
              jpg_available: jpg_available,
              png_available: png_available
            }

            case upsert_tile(attrs) do
              {:ok, _tile} ->
                Logger.debug("Inserted tile: #{tile_id}")
                :ok

              {:error, reason} ->
                Logger.error("Failed to insert tile #{tile_id}: #{inspect(reason)}")
                {:error, reason}
            end

          {:error, reason} ->
            Logger.error("Failed to parse header for #{tile_id}: #{inspect(reason)}")
            {:error, reason}
        end

      {:error, reason} ->
        Logger.error("Failed to check if tile exists #{tile_id}: #{inspect(reason)}")
        {:error, reason}
    end
  end

  # Generate random 8-character alphanumeric ID
  defp generate_id do
    :crypto.strong_rand_bytes(6)
    |> Base.url_encode64(padding: false)
    |> binary_part(0, 8)
  end
end