defmodule MicrowavepropWeb.SkewtLive do
  @moduledoc """
  `/skewt` interactive Skew-T-Log-P diagram.

  The user types an address, Maidenhead grid square, or callsign into
  the search bar; the page resolves it to lat/lon, snaps to the HRRR
  grid, and renders the latest analysis profile as a Skew-T plus the
  derived stability / refractivity stats. A time selector switches
  between the analysis hour and each available forecast hour out to
  HRRR's f18 horizon.
  """
  use MicrowavepropWeb, :live_view

  alias Microwaveprop.Propagation.ProfilesFile
  alias Microwaveprop.Weather.HrrrProfileLookup
  alias Microwaveprop.Weather.SoundingParams
  alias MicrowavepropWeb.SkewtLocationResolver
  alias MicrowavepropWeb.SkewtSvg

  @impl true
  def mount(_params, _session, socket) do
    {:ok,
     assign(socket,
       page_title: "Skew-T",
       query: "",
       location: nil,
       error: nil,
       valid_times: [],
       selected_valid_time: nil,
       profile: nil,
       derived: nil,
       svg: nil
     )}
  end

  @impl true
  def handle_params(params, _uri, socket) do
    query = String.trim(params["q"] || "")
    requested_time = parse_time(params["valid_time"])

    {:noreply, refresh(socket, query, requested_time)}
  end

  @impl true
  def handle_event("search", %{"q" => q}, socket) do
    {:noreply, push_patch(socket, to: ~p"/skewt?#{[q: q]}")}
  end

  def handle_event("select_time", %{"valid_time" => iso}, socket) do
    params = [q: socket.assigns.query, valid_time: iso]
    {:noreply, push_patch(socket, to: ~p"/skewt?#{params}")}
  end

  # ── Refresh logic ──────────────────────────────────────────────────

  defp refresh(socket, "", _time) do
    assign(socket,
      query: "",
      location: nil,
      error: nil,
      valid_times: [],
      selected_valid_time: nil,
      profile: nil,
      derived: nil,
      svg: nil
    )
  end

  defp refresh(socket, query, requested_time) do
    case SkewtLocationResolver.resolve(query) do
      {:ok, %{lat: lat, lon: lon} = location} ->
        valid_times = available_valid_times(lat, lon)

        chosen = pick_valid_time(valid_times, requested_time)

        {profile, derived, svg} =
          case chosen do
            nil ->
              {nil, nil, nil}

            time ->
              load_profile(time, lat, lon)
          end

        assign(socket,
          query: query,
          location: location,
          error: nil,
          valid_times: valid_times,
          selected_valid_time: chosen,
          profile: profile,
          derived: derived,
          svg: svg
        )

      {:error, reason} ->
        assign(socket,
          query: query,
          location: nil,
          error: reason,
          valid_times: [],
          selected_valid_time: nil,
          profile: nil,
          derived: nil,
          svg: nil
        )
    end
  end

  defp load_profile(valid_time, lat, lon) do
    cell = ProfilesFile.read_point(valid_time, lat, lon) || HrrrProfileLookup.read_point_near(valid_time, lat, lon)

    case cell do
      nil ->
        {nil, nil, nil}

      %{} = cell ->
        profile = extract_profile(cell)

        if profile == [] do
          {nil, nil, nil}
        else
          derived = SoundingParams.derive(profile)
          svg = SkewtSvg.render(profile)
          {profile, derived, svg}
        end
    end
  end

  defp extract_profile(cell) do
    cell[:profile] || cell["profile"] || []
  end

  defp available_valid_times(lat, lon) do
    # The chain produces analysis + 18 forecast hours every wall-clock
    # hour. By the time the next chain finishes the previous chain's
    # analysis is up to 70 min old, and during a missed cycle it can be
    # ~2 h old. A 1-hour past cutoff would leave the page empty while
    # the chain catches up — keep 3 h so a stale analysis still shows.
    now = DateTime.utc_now()
    past_cutoff = DateTime.add(now, -3 * 3600, :second)
    future_cutoff = DateTime.add(now, 18 * 3600, :second)

    on_disk =
      Enum.filter(ProfilesFile.list_valid_times(), fn t ->
        DateTime.compare(t, past_cutoff) != :lt and DateTime.compare(t, future_cutoff) != :gt
      end)

    case on_disk do
      [] ->
        # On-disk store is empty for this window — common in dev (no NFS
        # mount, no local Rust pipeline) and during missed-cycle windows
        # in prod. Fall back to whatever HRRR profiles the DB has near
        # the location, regardless of how old. Better to render historic
        # data than a "no profiles stored" stub.
        HrrrProfileLookup.list_valid_times_near(lat, lon)

      times ->
        Enum.sort(times, DateTime)
    end
  end

  defp pick_valid_time([], _requested), do: nil

  defp pick_valid_time(times, nil) do
    # Default = the most recent valid_time at or before "now". If
    # everything is in the future (cold start), fall back to the
    # earliest available.
    now = DateTime.utc_now()

    times
    |> Enum.filter(fn t -> DateTime.compare(t, now) != :gt end)
    |> case do
      [] -> List.first(times)
      past -> Enum.max(past, DateTime)
    end
  end

  defp pick_valid_time(times, %DateTime{} = requested) do
    case Enum.find(times, &(DateTime.compare(&1, requested) == :eq)) do
      nil -> pick_valid_time(times, nil)
      match -> match
    end
  end

  defp parse_time(nil), do: nil
  defp parse_time(""), do: nil

  defp parse_time(iso) when is_binary(iso) do
    case DateTime.from_iso8601(iso) do
      {:ok, dt, _} -> DateTime.truncate(dt, :second)
      _ -> nil
    end
  end

  # ── Render ─────────────────────────────────────────────────────────

  @impl true
  def render(assigns) do
    ~H"""
    <Layouts.app flash={@flash} current_scope={@current_scope} max_width="max-w-6xl">
      <.header>
        Skew-T-Log-P
        <:subtitle>
          Vertical atmospheric profile from the latest HRRR analysis (or any
          available forecast hour) for an address, grid square, or callsign.
        </:subtitle>
      </.header>

      <form phx-submit="search" class="mt-4 flex gap-2">
        <input
          type="text"
          name="q"
          value={@query}
          placeholder="EM12kp, W5ISP, or '123 Main St, Plano TX'"
          class="input input-bordered flex-1"
          autocomplete="off"
          autofocus
        />
        <button type="submit" class="btn btn-primary">Plot</button>
      </form>

      <%= if @error do %>
        <div role="alert" class="alert alert-error mt-4">
          <p>{@error}</p>
        </div>
      <% end %>

      <%= if @location do %>
        <div class="mt-4 flex flex-wrap items-baseline gap-4 text-sm">
          <span class="font-semibold">{@location.label}</span>
          <span class="opacity-70">
            {fmt_coord(@location.lat)}, {fmt_coord(@location.lon)}
          </span>
        </div>
      <% end %>

      <%= if @valid_times != [] do %>
        <div class="mt-4 flex flex-wrap gap-2">
          <%= for t <- @valid_times do %>
            <button
              type="button"
              phx-click="select_time"
              phx-value-valid_time={DateTime.to_iso8601(t)}
              class={[
                "btn btn-xs",
                if(@selected_valid_time && DateTime.compare(t, @selected_valid_time) == :eq,
                  do: "btn-primary",
                  else: "btn-outline"
                )
              ]}
            >
              {time_button_label(t, @valid_times)}
            </button>
          <% end %>
        </div>
      <% end %>

      <%= if @svg do %>
        <div class="mt-6 grid grid-cols-1 lg:grid-cols-3 gap-6">
          <div
            id="skewt-container"
            phx-hook="Skewt"
            phx-update="ignore"
            data-profile={Jason.encode!(@profile)}
            data-geometry={Jason.encode!(SkewtSvg.geometry())}
            class="lg:col-span-2 bg-base-100 rounded-box p-3 border border-base-300"
          >
            {Phoenix.HTML.raw(@svg)}
          </div>
          <div class="bg-base-200 rounded-box p-4 text-sm space-y-3">
            <h3 class="font-semibold text-base">Derived parameters</h3>
            <%= if @derived do %>
              <dl class="grid grid-cols-2 gap-x-3 gap-y-1.5">
                <%= for {label, value} <- derived_rows(@derived) do %>
                  <dt class="opacity-70">{label}</dt>
                  <dd class="font-mono text-right">{value}</dd>
                <% end %>
              </dl>

              <%= if @derived[:ducting_detected] && @derived[:ducts] != [] do %>
                <div class="mt-3 pt-3 border-t border-base-300 space-y-1">
                  <h4 class="font-semibold">Ducts</h4>
                  <%= for duct <- @derived.ducts do %>
                    <div class="font-mono text-xs">
                      base {round(duct["base"])} m → top {round(duct["top"])} m, ΔM {duct["strength"]}
                    </div>
                  <% end %>
                </div>
              <% end %>
            <% end %>
          </div>
        </div>
      <% else %>
        <%= if @location && @selected_valid_time do %>
          <div role="alert" class="alert alert-warning mt-6">
            <p>
              No HRRR profile is stored for this point at {fmt_time(@selected_valid_time)}.
              Profiles are written by the hourly chain and only kept for the active
              forecast window.
            </p>
          </div>
        <% else %>
          <%= if @location && @valid_times == [] do %>
            <div role="alert" class="alert alert-info mt-6">
              <p>
                No HRRR profiles are currently stored. Wait for the next hourly
                chain to publish, or check the propagation pipeline status.
              </p>
            </div>
          <% end %>
        <% end %>
      <% end %>
    </Layouts.app>
    """
  end

  defp fmt_coord(c) when is_number(c), do: :erlang.float_to_binary(c * 1.0, decimals: 3)
  defp fmt_coord(_), do: "—"

  defp fmt_time(%DateTime{} = t) do
    Calendar.strftime(t, "%Y-%m-%d %H:%MZ")
  end

  defp time_button_label(%DateTime{} = t, all_times) do
    base = Enum.min(all_times, DateTime)
    delta_h = div(DateTime.diff(t, base, :second), 3600)
    IO.iodata_to_binary("f#{:io_lib.format("~2..0B", [delta_h])} · #{Calendar.strftime(t, "%H:%MZ")}")
  end

  defp derived_rows(d) do
    [
      {"Surface T", fmt_temp(d[:surface_temp_c])},
      {"Surface Td", fmt_temp(d[:surface_dewpoint_c])},
      {"Surface P", fmt_num(d[:surface_pressure_mb], "mb")},
      {"Surface N", fmt_num(d[:surface_refractivity], "")},
      {"Min dN/dh", fmt_num(d[:min_refractivity_gradient], "/km")},
      {"PWAT", fmt_num(d[:precipitable_water_mm], "mm")},
      {"BL depth", fmt_num(d[:boundary_layer_depth_m], "m")},
      {"K-index", fmt_num(d[:k_index], "")},
      {"Lifted index", fmt_num(d[:lifted_index], "")},
      {"Ducting", if(d[:ducting_detected], do: "yes", else: "no")},
      {"Levels", to_string(d[:level_count] || 0)}
    ]
  end

  defp fmt_temp(nil), do: "—"
  defp fmt_temp(v) when is_number(v), do: "#{Float.round(v * 1.0, 1)} °C"

  defp fmt_num(nil, _suffix), do: "—"
  defp fmt_num(v, ""), do: format_value(v)
  defp fmt_num(v, suffix), do: "#{format_value(v)} #{suffix}"

  defp format_value(v) when is_float(v), do: v |> Float.round(1) |> :erlang.float_to_binary(decimals: 1)
  defp format_value(v) when is_integer(v), do: Integer.to_string(v)
  defp format_value(v), do: to_string(v)
end