defmodule JPLEphem do
  @moduledoc """
  JPL Ephemeris Library for Elixir - Main API Module

  This module provides a unified interface to the JPL Ephemeris library,
  offering convenient access to astronomical calculations, coordinate
  transformations, and time scale conversions.

  ## Quick Start

      # Time conversions
      {:ok, jd} = JPLEphem.utc_to_jd(DateTime.utc_now())
      {:ok, datetime} = JPLEphem.jd_to_utc(jd)

      # Coordinate transformations
      {:ok, ecliptic} = JPLEphem.icrf_to_ecliptic({1.0, 0.0, 0.0})
      {:ok, {ra, dec}} = JPLEphem.to_ra_dec({1.0, 0.0, 0.0})

      # Caching
      JPLEphem.cache_put(:mars, position_data, 3600)
      {:ok, data} = JPLEphem.cache_get(:mars)

  ## Modules

  - `JPLEphem.Time` - Time scale conversions and Julian Day calculations
  - `JPLEphem.Coord` - Coordinate system transformations and vector math
  - `JPLEphem.Cache` - High-performance caching with TTL support
  """

  alias JPLEphem.{Time, Coord, Cache}

  @type vector3 :: {float(), float(), float()}
  @type datetime :: DateTime.t()
  @type julian_day :: float()
  @type cache_key :: any()
  @type cache_value :: any()

  # Time conversion functions

  @doc """
  Convert UTC datetime to Julian Day.

  ## Examples

      iex> JPLEphem.utc_to_jd(~U[2025-01-01 12:00:00Z])
      {:ok, 2460677.0}

  """
  @spec utc_to_jd(datetime()) :: {:ok, julian_day()} | {:error, atom()}
  def utc_to_jd(datetime), do: Time.utc_to_jd(datetime)

  @doc """
  Convert Julian Day to UTC datetime.

  ## Examples

      iex> JPLEphem.jd_to_utc(2460677.0)
      {:ok, ~U[2025-01-01 12:00:00.000000Z]}

  """
  @spec jd_to_utc(julian_day()) :: {:ok, datetime()} | {:error, atom()}
  def jd_to_utc(jd), do: Time.jd_to_utc(jd)

  @doc """
  Convert UTC to Terrestrial Time (TT).

  ## Examples

      iex> {:ok, tt_jd} = JPLEphem.utc_to_tt(~U[2025-01-01 12:00:00Z])
      iex> is_float(tt_jd) and tt_jd > 2460677.0
      true

  """
  @spec utc_to_tt(datetime()) :: {:ok, julian_day()} | {:error, atom()}
  def utc_to_tt(datetime), do: Time.utc_to_tt(datetime)

  @doc """
  Convert Terrestrial Time (TT) to Barycentric Dynamical Time (TDB).

  ## Examples

      iex> {:ok, tdb_jd} = JPLEphem.tt_to_tdb(2460677.0)
      iex> is_float(tdb_jd) and tdb_jd > 2460676.0 and tdb_jd < 2460678.0
      true

  """
  @spec tt_to_tdb(julian_day()) :: {:ok, julian_day()} | {:error, atom()}
  def tt_to_tdb(tt_jd), do: Time.tt_to_tdb(tt_jd)

  @doc """
  Get leap seconds for a given UTC datetime.

  ## Examples

      iex> {:ok, leap_secs} = JPLEphem.leap_seconds_at(~U[2025-01-01 12:00:00Z])
      iex> is_integer(leap_secs) and leap_secs > 30
      true

  """
  @spec leap_seconds_at(datetime()) :: {:ok, integer()} | {:error, atom()}
  def leap_seconds_at(datetime), do: Time.leap_seconds_at(datetime)

  # Coordinate transformation functions

  @doc """
  Transform coordinates from ICRF to Ecliptic system.

  ## Examples

      iex> JPLEphem.icrf_to_ecliptic({1.0, 0.0, 0.0})
      {:ok, {1.0, 0.0, 0.0}}

  """
  @spec icrf_to_ecliptic(vector3()) :: {:ok, vector3()} | {:error, atom()}
  def icrf_to_ecliptic(vector), do: Coord.icrf_to_ecliptic(vector)

  @doc """
  Transform coordinates from Ecliptic to ICRF system.

  ## Examples

      iex> JPLEphem.ecliptic_to_icrf({1.0, 0.0, 0.0})
      {:ok, {1.0, 0.0, 0.0}}

  """
  @spec ecliptic_to_icrf(vector3()) :: {:ok, vector3()} | {:error, atom()}
  def ecliptic_to_icrf(vector), do: Coord.ecliptic_to_icrf(vector)

  @doc """
  Convert Cartesian to spherical coordinates.

  Uses physics convention where phi is polar angle from Z-axis.

  ## Examples

      iex> JPLEphem.to_spherical({3.0, 4.0, 0.0})
      {:ok, {5.0, 0.9272952180016122, 1.5707963267948966}}

  """
  @spec to_spherical(vector3()) :: {:ok, {float(), float(), float()}} | {:error, atom()}
  def to_spherical(vector), do: Coord.to_spherical(vector)

  @doc """
  Convert spherical to Cartesian coordinates.

  Uses physics convention where phi is polar angle from Z-axis.

  ## Examples

      iex> {:ok, {x, y, z}} = JPLEphem.from_spherical(5.0, 0.9272952180016122, 1.5707963267948966)
      iex> abs(x - 3.0) < 1.0e-10 and abs(y - 4.0) < 1.0e-10 and abs(z) < 1.0e-10
      true

  """
  @spec from_spherical(float(), float(), float()) :: {:ok, vector3()} | {:error, atom()}
  def from_spherical(r, theta, phi), do: Coord.from_spherical(r, theta, phi)

  @doc """
  Convert Cartesian coordinates to Right Ascension and Declination.

  ## Examples

      iex> JPLEphem.to_ra_dec({1.0, 0.0, 0.0})
      {:ok, {0.0, 0.0}}

  """
  @spec to_ra_dec(vector3()) :: {:ok, {float(), float()}} | {:error, atom()}
  def to_ra_dec(vector), do: Coord.to_ra_dec(vector)

  @doc """
  Convert Right Ascension and Declination to Cartesian coordinates.

  ## Examples

      iex> JPLEphem.from_ra_dec({0.0, 0.0}, 1.0)
      {:ok, {1.0, 0.0, 0.0}}

  """
  @spec from_ra_dec({float(), float()}, float()) :: {:ok, vector3()} | {:error, atom()}
  def from_ra_dec(ra_dec, distance), do: Coord.from_ra_dec(ra_dec, distance)

  @doc """
  Convert AU to kilometers.

  ## Examples

      iex> JPLEphem.au_to_km({1.0, 0.5, 0.0})
      {149597870.7, 74798935.35, 0.0}

  """
  @spec au_to_km(vector3()) :: vector3()
  def au_to_km(vector), do: Coord.au_to_km(vector)

  @doc """
  Convert kilometers to AU.

  ## Examples

      iex> JPLEphem.km_to_au({149597870.7, 74798935.35, 0.0})
      {1.0, 0.5, 0.0}

  """
  @spec km_to_au(vector3()) :: vector3()
  def km_to_au(vector), do: Coord.km_to_au(vector)

  # Vector mathematics

  @doc """
  Calculate vector magnitude.

  ## Examples

      iex> JPLEphem.vector_magnitude({3.0, 4.0, 0.0})
      5.0

  """
  @spec vector_magnitude(vector3()) :: float()
  def vector_magnitude(vector), do: Coord.vector_magnitude(vector)

  @doc """
  Normalize a vector to unit length.

  ## Examples

      iex> {x, y, z} = JPLEphem.normalize_vector({3.0, 4.0, 0.0})
      iex> abs(x - 0.6) < 1.0e-10 and abs(y - 0.8) < 1.0e-10 and abs(z) < 1.0e-10
      true

  """
  @spec normalize_vector(vector3()) :: vector3() | {:error, atom()}
  def normalize_vector(vector), do: Coord.normalize_vector(vector)

  @doc """
  Calculate dot product of two vectors.

  ## Examples

      iex> JPLEphem.dot_product({1.0, 2.0, 3.0}, {4.0, 5.0, 6.0})
      32.0

  """
  @spec dot_product(vector3(), vector3()) :: float()
  def dot_product(v1, v2), do: Coord.dot_product(v1, v2)

  @doc """
  Calculate cross product of two vectors.

  ## Examples

      iex> JPLEphem.cross_product({1.0, 0.0, 0.0}, {0.0, 1.0, 0.0})
      {0.0, 0.0, 1.0}

  """
  @spec cross_product(vector3(), vector3()) :: vector3()
  def cross_product(v1, v2), do: Coord.cross_product(v1, v2)

  # Cache functions

  @doc """
  Store a value in the cache with TTL.

  ## Examples

      iex> JPLEphem.cache_put(:doctest_key, {{1.0, 2.0, 3.0}, {0.1, 0.2, 0.3}}, 3600)
      :ok

  """
  @spec cache_put(cache_key(), cache_value(), number()) :: :ok
  def cache_put(key, value, ttl \\ nil), do: Cache.put(key, value, ttl)

  @doc """
  Retrieve a value from the cache.

  ## Examples

      iex> JPLEphem.cache_put(:doctest_get, {{1.0, 2.0, 3.0}, {0.1, 0.2, 0.3}}, 3600)
      iex> JPLEphem.cache_get(:doctest_get)
      {:ok, {{1.0, 2.0, 3.0}, {0.1, 0.2, 0.3}}}

  """
  @spec cache_get(cache_key()) :: {:ok, cache_value()} | :not_found
  def cache_get(key), do: Cache.get(key)

  @doc """
  Delete a key from the cache.

  ## Examples

      iex> JPLEphem.cache_put(:doctest_del, {1, 2, 3}, 3600)
      iex> JPLEphem.cache_delete(:doctest_del)
      :ok

  """
  @spec cache_delete(cache_key()) :: :ok
  def cache_delete(key), do: Cache.delete(key)

  @doc """
  Clear all cache entries.

  ## Examples

      iex> JPLEphem.cache_clear()
      :ok

  """
  @spec cache_clear() :: :ok
  def cache_clear(), do: Cache.clear()

  @doc """
  Get cache statistics.

  ## Examples

      iex> stats = JPLEphem.cache_stats()
      iex> is_map(stats) and Map.has_key?(stats, :size) and Map.has_key?(stats, :hits)
      true

  """
  @spec cache_stats() :: map()
  def cache_stats(), do: Cache.stats()

  @doc """
  Get current cache size.

  ## Examples

      iex> size = JPLEphem.cache_size()
      iex> is_integer(size) and size >= 0
      true

  """
  @spec cache_size() :: non_neg_integer()
  def cache_size(), do: Cache.size()

  @doc """
  Trigger garbage collection of expired cache entries.

  ## Examples

      iex> JPLEphem.cache_gc()
      :ok

  """
  @spec cache_gc() :: :ok
  def cache_gc(), do: Cache.gc()

  # Convenience functions

  @doc """
  Get current time as Julian Day.

  ## Examples

      iex> {:ok, jd} = JPLEphem.now_jd()
      iex> is_float(jd)
      true

  """
  @spec now_jd() :: {:ok, julian_day()} | {:error, atom()}
  def now_jd(), do: utc_to_jd(DateTime.utc_now())

  @doc """
  Get current time in Terrestrial Time (TT).

  ## Examples

      iex> {:ok, tt} = JPLEphem.now_tt()
      iex> is_float(tt)
      true

  """
  @spec now_tt() :: {:ok, julian_day()} | {:error, atom()}
  def now_tt(), do: utc_to_tt(DateTime.utc_now())

  @doc """
  Get current time in Barycentric Dynamical Time (TDB).

  ## Examples

      iex> {:ok, tdb} = JPLEphem.now_tdb()
      iex> is_float(tdb)
      true

  """
  @spec now_tdb() :: {:ok, julian_day()} | {:error, atom()}
  def now_tdb() do
    with {:ok, tt} <- now_tt(),
         {:ok, tdb} <- tt_to_tdb(tt) do
      {:ok, tdb}
    end
  end
end