defmodule MicrowavepropWeb.AboutLive do
  @moduledoc false
  use MicrowavepropWeb, :live_view

  alias Microwaveprop.Repo

  @impl true
  def mount(_params, _session, socket) do
    {:ok,
     socket
     |> assign(:page_title, "About")
     |> assign(:stats, fetch_stats())}
  end

  @impl true
  def render(assigns) do
    ~H"""
    <Layouts.app flash={@flash} current_scope={@current_scope} max_width="max-w-4xl">
      <.header>
        About NTMS Propagation Prediction
        <:subtitle>What we're building and why.</:subtitle>
      </.header>

      <section class="prose prose-sm max-w-none dark:prose-invert">
        <h2>What we're trying to do</h2>
        <p>
          Microwave propagation above 10 GHz is dominated by the lower atmosphere:
          humidity gradients, temperature inversions, ducting layers, rain cells,
          and hyper-local refractivity structure. At 10, 24, 47, 76, 122, and 241 GHz
          these effects decide whether a contact happens at 50 km or 500 km — and the
          window often lasts minutes, not hours.
        </p>
        <p>
          Traditionally microwave contacts are ruled by line of sight, but we've seen that is incorrect. This project is an attempt to build a data-driven
          propagation prediction model specifically for the amateur microwave bands,
          using hourly numerical weather forecasts, historical contact records, and
          eventually calibrated beacon measurements.
        </p>

        <h2>The approach</h2>
        <p>
          We pair two things that most propagation tools keep separate:
        </p>
        <ol>
          <li>
            <strong>Atmospheric state</strong> — hourly 3 km HRRR forecasts
            (surface fields plus pressure-level profiles), hourly surface
            observations from ASOS, 12-hourly upper-air soundings, and gridded
            IEMRE reanalysis. From these we derive refractivity profiles,
            ducting detection, minimum refractivity gradient, precipitable water,
            boundary-layer depth, and a 9-factor composite score for every
            0.125° cell on a CONUS grid, for each hour of an 18-hour forecast.
          </li>
          <li>
            <strong>Historical contacts</strong> — 58k+ amateur microwave QSOs
            tagged with the atmospheric conditions at both ends and along the
            path at the exact time they happened. That gives us a ground-truth
            dataset we can use to calibrate the scoring weights and, eventually,
            train a machine learning model that predicts contact success given
            conditions.
          </li>
        </ol>
        <p>
          The current scoring algorithm is a weighted sum of nine factors
          (humidity, time of day, T–Td depression, refractivity gradient, sky
          cover, season, rain, wind, pressure) with band-dependent weights —
          humidity helps at 10 GHz via enhanced refractivity but hurts at
          24+ GHz via absorption, for example. Every coefficient in that
          formula is a hypothesis waiting to be tested against the contact
          and beacon data.
        </p>

        <h2>What we've collected</h2>
        <p>Live counts from the production database:</p>

        <div class="not-prose my-4 grid grid-cols-2 md:grid-cols-3 gap-3">
          <.stat_card label="Contacts" value={@stats.contacts} />
          <.stat_card label="Weather stations" value={@stats.weather_stations} />
          <.stat_card label="Surface observations" value={@stats.surface_observations} />
          <.stat_card label="Upper-air soundings" value={@stats.soundings} />
          <.stat_card label="HRRR profiles" value={@stats.hrrr_profiles} />
          <.stat_card label="IEMRE gridded obs" value={@stats.iemre_observations} />
          <.stat_card label="Terrain profiles" value={@stats.terrain_profiles} />
          <.stat_card label="Propagation scores" value={@stats.propagation_scores} />
          <.stat_card label="Beacons" value={@stats.beacons} />
          <.stat_card label="Commercial link samples" value={@stats.commercial_samples} />
        </div>

        <h2>The stack</h2>
        <ul>
          <li>
            <strong>Backend:</strong> Elixir / Phoenix 1.8 with LiveView for the
            real-time map, Ecto on PostgreSQL for storage, Oban for the
            background data pipelines (HRRR fetch, terrain, ASOS, soundings,
            IEMRE, solar indices, commercial links), Bandit as the HTTP server.
          </li>
          <li>
            <strong>Frontend:</strong> LiveView with Leaflet for maps, Canvas
            tile layers for the HRRR heatmap (we render 0.125° cells at
            interactive frame rates), Tailwind v4 + daisyUI for layout, esbuild
            for JS bundling.
          </li>
          <li>
            <strong>Physics:</strong> ITU-R P.526-16 knife-edge + Deygout
            3-edge terrain diffraction, ITU-R P.838-3 rain attenuation,
            dynamic k-factor from live HRRR refractivity gradients, great-circle
            geometry for link budgets, Free-Space Path Loss with frequency-
            dependent O₂ and H₂O absorption per band.
          </li>
          <li>
            <strong>Machine learning:</strong> Nx / Axon / EXLA scaffolding for
            a 13-feature (8 atmospheric + 4 cyclical temporal + 1 log-frequency)
            feed-forward network, 64 → 32 → 1 sigmoid. Not trained yet —
            waiting on a larger calibration dataset.
          </li>
          <li>
            <strong>Data sources:</strong> NOAA HRRR model (AWS S3, hourly
            analysis + 18 h forecasts), Iowa Environmental Mesonet (ASOS &amp;
            upper-air soundings), IEMRE gridded reanalysis, SRTM 90 m terrain
            tiles, SNMP polling of seven commercial microwave links near DFW
            at 5-minute intervals, Copernicus ERA5 for pre-2014 contact
            enrichment.
          </li>
        </ul>

        <h2>Where this goes next</h2>
        <ul>
          <li>
            <strong>Beacon calibration.</strong> A distributed network of
            amateur receivers continuously reporting CW beacon signal levels,
            feeding ground-truth measurements back into the scoring algorithm.
            Beacon submissions are now open to anyone via the Beacons page.
          </li>
          <li>
            <strong>Scoring weight calibration.</strong> Fit the 9-factor
            weights against recorded QSO distances / counts per band so the
            composite score reflects real propagation rather than intuition.
          </li>
          <li>
            <strong>ML model training.</strong> Once we have enough labeled
            contact+condition pairs, train the Axon model to replace or augment
            the hand-tuned scoring function.
          </li>
          <li>
            <strong>Better inputs.</strong> MRMS for precipitation at
            24+ GHz (where rain attenuation dominates), RTMA/URMA surface
            analysis blending, GOES total precipitable water.
          </li>
        </ul>

        <p class="text-xs opacity-60 mt-8">
          Built by and for the <a href="https://www.ntms.org" target="_blank">North Texas Microwave Society</a>.
        </p>
      </section>
    </Layouts.app>
    """
  end

  attr :label, :string, required: true
  attr :value, :integer, required: true

  defp stat_card(assigns) do
    ~H"""
    <div class="rounded-lg border border-base-300 bg-base-200/40 p-3">
      <div class="text-xs opacity-70 uppercase tracking-wide">{@label}</div>
      <div class="text-xl font-bold tabular-nums">{format_count(@value)}</div>
    </div>
    """
  end

  # For tables that get huge (tens of millions of rows), using count(*) on
  # every About page load is wasteful. We use PostgreSQL's pg_class.reltuples
  # estimate — it's maintained by ANALYZE and is accurate to within a few
  # percent, which is plenty for "big number on a marketing page."
  @estimate_tables ~w(hrrr_profiles propagation_scores surface_observations)

  @stat_keys ~w(
    contacts weather_stations surface_observations soundings hrrr_profiles
    iemre_observations terrain_profiles propagation_scores beacons
    commercial_samples
  )a

  defp fetch_stats do
    %{
      contacts: count_exact("contacts"),
      weather_stations: count_exact("weather_stations"),
      surface_observations: count_estimate("surface_observations"),
      soundings: count_exact("soundings"),
      hrrr_profiles: count_estimate("hrrr_profiles"),
      iemre_observations: count_exact("iemre_observations"),
      terrain_profiles: count_exact("terrain_profiles"),
      propagation_scores: count_estimate("propagation_scores"),
      beacons: count_exact("beacons"),
      commercial_samples: count_exact("commercial_samples")
    }
  rescue
    _ -> Map.new(@stat_keys, fn k -> {k, 0} end)
  end

  defp count_exact(table) do
    %Postgrex.Result{rows: [[count]]} =
      Repo.query!("SELECT count(*) FROM #{table}")

    count
  end

  defp count_estimate(table) when table in @estimate_tables do
    %Postgrex.Result{rows: [[estimate]]} =
      Repo.query!("SELECT reltuples::bigint FROM pg_class WHERE relname = $1", [table])

    max(estimate || 0, 0)
  end

  defp format_count(n) when is_integer(n) and n >= 1_000_000 do
    "#{Float.round(n / 1_000_000, 1)}M"
  end

  defp format_count(n) when is_integer(n) and n >= 1_000 do
    "#{Float.round(n / 1_000, 1)}k"
  end

  defp format_count(n) when is_integer(n), do: Integer.to_string(n)
  defp format_count(_), do: "—"
end