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

  alias Microwaveprop.Propagation.BandConfig
  alias Microwaveprop.Propagation.Scorer
  alias Microwaveprop.Radio.CallsignClient
  alias Microwaveprop.Radio.Maidenhead
  alias Microwaveprop.Terrain.ElevationClient
  alias Microwaveprop.Terrain.TerrainAnalysis
  alias Microwaveprop.Weather

  @band_options [
    {"10 GHz", "10000"},
    {"24 GHz", "24000"},
    {"47 GHz", "47000"},
    {"68 GHz", "68000"},
    {"76 GHz", "75000"},
    {"122 GHz", "122000"},
    {"134 GHz", "134000"},
    {"241 GHz", "241000"}
  ]

  @impl true
  def mount(_params, _session, socket) do
    {:ok,
     assign(socket,
       page_title: "Path Calculator",
       band_options: @band_options,
       source: "",
       destination: "",
       band: "10000",
       result: nil,
       error: nil,
       computing: false
     )}
  end

  @impl true
  def handle_event("calculate", %{"source" => source, "destination" => dest, "band" => band}, socket) do
    socket = assign(socket, source: source, destination: dest, band: band, error: nil, computing: true, result: nil)

    send(self(), {:compute_path, source, dest, String.to_integer(band)})

    {:noreply, socket}
  end

  @impl true
  def handle_info({:compute_path, source, dest, band_mhz}, socket) do
    case compute_path(source, dest, band_mhz) do
      {:ok, result} ->
        {:noreply, assign(socket, result: result, computing: false)}

      {:error, reason} ->
        {:noreply, assign(socket, error: reason, computing: false)}
    end
  end

  defp compute_path(source, dest, band_mhz) do
    with {:ok, src} <- resolve_location(source),
         {:ok, dst} <- resolve_location(dest) do
      band_config = BandConfig.get(band_mhz) || BandConfig.get(10_000)
      freq_ghz = band_mhz / 1000

      dist_km = haversine_km(src.lat, src.lon, dst.lat, dst.lon)
      bearing = bearing_deg(src.lat, src.lon, dst.lat, dst.lon)

      # Terrain profile
      terrain_result =
        case ElevationClient.fetch_elevation_profile(src.lat, src.lon, dst.lat, dst.lon, 64, download: true) do
          {:ok, profile} ->
            analysis = TerrainAnalysis.analyse(profile, dist_km, freq_ghz)
            %{profile: profile, analysis: analysis}

          {:error, _} ->
            nil
        end

      # HRRR profiles along path
      now = DateTime.utc_now()
      midlat = (src.lat + dst.lat) / 2
      midlon = (src.lon + dst.lon) / 2

      hrrr_profiles =
        [{src.lat, src.lon}, {midlat, midlon}, {dst.lat, dst.lon}]
        |> Enum.map(fn {lat, lon} -> Weather.find_nearest_hrrr(lat, lon, now) end)
        |> Enum.reject(&is_nil/1)

      # Build conditions and score
      {conditions, scoring} = build_scoring(hrrr_profiles, src, now, band_config)

      # Loss budget
      loss_budget = compute_loss_budget(dist_km, freq_ghz, band_config, terrain_result, conditions)

      {:ok,
       %{
         source: src,
         destination: dst,
         band_config: band_config,
         band_mhz: band_mhz,
         freq_ghz: freq_ghz,
         dist_km: dist_km,
         bearing: bearing,
         terrain: terrain_result,
         conditions: conditions,
         scoring: scoring,
         loss_budget: loss_budget,
         hrrr_count: length(hrrr_profiles)
       }}
    end
  end

  defp resolve_location(input) do
    input = String.trim(input)

    cond do
      input == "" ->
        {:error, "Location is required"}

      maidenhead?(input) ->
        case Maidenhead.to_latlon(input) do
          {:ok, {lat, lon}} -> {:ok, %{lat: lat, lon: lon, label: String.upcase(input), type: :grid}}
          :error -> {:error, "Invalid grid square: #{input}"}
        end

      true ->
        case CallsignClient.locate(input) do
          {:ok, info} ->
            {:ok,
             %{lat: info.lat, lon: info.lon, label: String.upcase(info.callsign), grid: info.gridsquare, type: :callsign}}

          {:error, reason} ->
            {:error, "Could not find #{input}: #{reason}"}
        end
    end
  end

  defp maidenhead?(input) do
    String.length(input) >= 4 and String.length(input) <= 10 and
      Regex.match?(~r/^[A-Ra-r]{2}[0-9]{2}/i, input)
  end

  defp build_scoring([], _src, _now, _band_config), do: {nil, nil}

  defp build_scoring(profiles, src, now, band_config) do
    temps = profiles |> Enum.map(& &1.surface_temp_c) |> Enum.reject(&is_nil/1)
    dewpoints = profiles |> Enum.map(& &1.surface_dewpoint_c) |> Enum.reject(&is_nil/1)

    if temps == [] or dewpoints == [] do
      {nil, nil}
    else
      avg_temp_c = Enum.sum(temps) / length(temps)
      avg_dewpoint_c = Enum.sum(dewpoints) / length(dewpoints)

      pressures = profiles |> Enum.map(& &1.surface_pressure_mb) |> Enum.reject(&is_nil/1)
      gradients = profiles |> Enum.map(& &1.min_refractivity_gradient) |> Enum.reject(&is_nil/1)
      bl_depths = profiles |> Enum.map(& &1.hpbl_m) |> Enum.reject(&is_nil/1)
      pwats = profiles |> Enum.map(& &1.pwat_mm) |> Enum.reject(&is_nil/1)

      conditions = %{
        abs_humidity: Scorer.absolute_humidity(avg_temp_c, avg_dewpoint_c),
        temp_f: Scorer.c_to_f(avg_temp_c),
        dewpoint_f: Scorer.c_to_f(avg_dewpoint_c),
        temp_c: avg_temp_c,
        dewpoint_c: avg_dewpoint_c,
        wind_speed_kts: nil,
        sky_cover_pct: nil,
        utc_hour: now.hour,
        utc_minute: now.minute,
        month: now.month,
        longitude: src.lon,
        pressure_mb: if(pressures != [], do: Enum.min(pressures)),
        prev_pressure_mb: nil,
        rain_rate_mmhr: 0.0,
        min_refractivity_gradient: if(gradients != [], do: Enum.min(gradients)),
        bl_depth_m: if(bl_depths != [], do: Enum.sum(bl_depths) / length(bl_depths)),
        pwat_mm: if(pwats != [], do: Enum.sum(pwats) / length(pwats))
      }

      scoring = Scorer.composite_score(conditions, band_config)
      {conditions, scoring}
    end
  end

  defp compute_loss_budget(dist_km, freq_ghz, band_config, terrain_result, conditions) do
    freq_mhz = freq_ghz * 1000
    fspl = 20 * :math.log10(max(dist_km, 0.001)) + 20 * :math.log10(freq_mhz) + 32.44

    o2_loss = band_config.o2_db_km * dist_km
    h2o_coeff = band_config.h2o_coeff

    abs_humidity =
      if conditions do
        conditions.abs_humidity
      else
        7.5
      end

    h2o_loss = h2o_coeff * abs_humidity * dist_km

    rain_loss =
      if conditions && conditions.rain_rate_mmhr > 0 do
        gamma = band_config.rain_k * :math.pow(conditions.rain_rate_mmhr, band_config.rain_alpha)
        gamma * dist_km
      else
        0.0
      end

    diffraction_loss =
      if terrain_result do
        terrain_result.analysis.diffraction_db
      else
        0.0
      end

    total = fspl + o2_loss + h2o_loss + rain_loss + diffraction_loss

    %{
      fspl: Float.round(fspl, 1),
      o2: Float.round(o2_loss, 2),
      h2o: Float.round(h2o_loss, 2),
      rain: Float.round(rain_loss, 2),
      diffraction: Float.round(diffraction_loss, 1),
      total: Float.round(total, 1)
    }
  end

  # ── Geo helpers ──

  defp haversine_km(lat1, lon1, lat2, lon2) do
    r = 6371.0
    dlat = deg_to_rad(lat2 - lat1)
    dlon = deg_to_rad(lon2 - lon1)
    a = :math.sin(dlat / 2) ** 2 + :math.cos(deg_to_rad(lat1)) * :math.cos(deg_to_rad(lat2)) * :math.sin(dlon / 2) ** 2
    2 * r * :math.asin(:math.sqrt(a))
  end

  defp bearing_deg(lat1, lon1, lat2, lon2) do
    lat1r = deg_to_rad(lat1)
    lat2r = deg_to_rad(lat2)
    dlonr = deg_to_rad(lon2 - lon1)
    y = :math.sin(dlonr) * :math.cos(lat2r)
    x = :math.cos(lat1r) * :math.sin(lat2r) - :math.sin(lat1r) * :math.cos(lat2r) * :math.cos(dlonr)
    b = :math.atan2(y, x) * 180 / :math.pi()
    Float.round(:math.fmod(b + 360, 360), 1)
  end

  defp deg_to_rad(d), do: d * :math.pi() / 180

  # ── Score tier helpers ──

  defp tier_label(score) when score >= 80, do: "EXCELLENT"
  defp tier_label(score) when score >= 65, do: "GOOD"
  defp tier_label(score) when score >= 50, do: "MARGINAL"
  defp tier_label(score) when score >= 33, do: "POOR"
  defp tier_label(_), do: "NEGLIGIBLE"

  defp tier_color(score) when score >= 80, do: "#00ffa3"
  defp tier_color(score) when score >= 65, do: "#7dffd4"
  defp tier_color(score) when score >= 50, do: "#ffe566"
  defp tier_color(score) when score >= 33, do: "#ff9044"
  defp tier_color(_), do: "#ff4f4f"

  defp terrain_verdict_class("CLEAR"), do: "badge badge-success"
  defp terrain_verdict_class("FRESNEL_MINOR"), do: "badge badge-warning"
  defp terrain_verdict_class("FRESNEL_PARTIAL"), do: "badge badge-warning"
  defp terrain_verdict_class("BLOCKED"), do: "badge badge-error"
  defp terrain_verdict_class(_), do: "badge"

  defp format_number(n) when is_float(n), do: :erlang.float_to_binary(n, decimals: 1)
  defp format_number(n), do: to_string(n)

  # ── Render ──

  @impl true
  def render(assigns) do
    ~H"""
    <Layouts.app flash={@flash} max_width="max-w-6xl">
      <.header>
        Path Calculator
        <:subtitle>Analyze microwave propagation between two points</:subtitle>
      </.header>

      <form phx-submit="calculate" class="bg-base-200 rounded-box p-4 mb-6">
        <div class="grid grid-cols-1 md:grid-cols-4 gap-4 items-end">
          <div class="fieldset">
            <label class="label text-sm font-medium">Source (callsign or grid)</label>
            <input
              type="text"
              name="source"
              value={@source}
              placeholder="W5ISP or EM13sf"
              class="input input-bordered w-full"
              required
            />
          </div>
          <div class="fieldset">
            <label class="label text-sm font-medium">Destination (callsign or grid)</label>
            <input
              type="text"
              name="destination"
              value={@destination}
              placeholder="K5TR or EM00cd"
              class="input input-bordered w-full"
              required
            />
          </div>
          <div class="fieldset">
            <label class="label text-sm font-medium">Band</label>
            <select name="band" class="select select-bordered w-full">
              <%= for {label, value} <- @band_options do %>
                <option value={value} selected={value == @band}>{label}</option>
              <% end %>
            </select>
          </div>
          <button type="submit" class="btn btn-primary" disabled={@computing}>
            <%= if @computing do %>
              <span class="loading loading-spinner loading-sm"></span> Computing...
            <% else %>
              Calculate
            <% end %>
          </button>
        </div>
      </form>

      <%= if @error do %>
        <div class="alert alert-error mb-6">{@error}</div>
      <% end %>

      <%= if @result do %>
        <.path_results result={@result} />
      <% end %>
    </Layouts.app>
    """
  end

  defp path_results(assigns) do
    ~H"""
    <%!-- Map --%>
    <div
      id="path-map"
      phx-hook="ContactMap"
      phx-update="ignore"
      data-pos1={Jason.encode!(%{lat: @result.source.lat, lon: @result.source.lon})}
      data-pos2={Jason.encode!(%{lat: @result.destination.lat, lon: @result.destination.lon})}
      data-station1={@result.source.label}
      data-station2={@result.destination.label}
      class="w-full h-64 md:h-80 rounded-box overflow-hidden mb-4"
    >
    </div>

    <%!-- Terrain profile --%>
    <%= if @result.terrain do %>
      <div
        id="path-elevation"
        phx-hook="ElevationProfile"
        phx-update="ignore"
        data-profile={Jason.encode!(elevation_data(@result))}
        class="w-full h-48 md:h-56 rounded-box overflow-hidden mb-6 bg-base-200"
      >
      </div>
    <% end %>

    <%!-- Summary cards --%>
    <div class="grid grid-cols-1 md:grid-cols-3 gap-4 mb-6">
      <%!-- Link Summary --%>
      <div class="bg-base-200 rounded-box p-4">
        <div class="text-xs opacity-60 mb-2">Link Summary</div>
        <div class="space-y-1 text-sm">
          <div class="flex justify-between">
            <span>Distance</span>
            <span class="font-mono">{format_number(@result.dist_km)} km</span>
          </div>
          <div class="flex justify-between">
            <span>Bearing</span>
            <span class="font-mono">{format_number(@result.bearing)}&deg;</span>
          </div>
          <div class="flex justify-between">
            <span>Band</span>
            <span class="font-mono">{@result.band_config.label}</span>
          </div>
          <%= if @result.terrain do %>
            <div class="flex justify-between">
              <span>Terrain</span>
              <span class={terrain_verdict_class(@result.terrain.analysis.verdict)}>
                {@result.terrain.analysis.verdict}
              </span>
            </div>
          <% end %>
          <div class="flex justify-between">
            <span>HRRR Profiles</span>
            <span class="font-mono">{@result.hrrr_count} / 3</span>
          </div>
        </div>
      </div>

      <%!-- Loss Budget --%>
      <div class="bg-base-200 rounded-box p-4">
        <div class="text-xs opacity-60 mb-2">Loss Budget</div>
        <div class="space-y-1 text-sm">
          <div class="flex justify-between">
            <span>Free Space</span>
            <span class="font-mono">{@result.loss_budget.fspl} dB</span>
          </div>
          <div class="flex justify-between">
            <span>O&#8322; Absorption</span>
            <span class="font-mono">{@result.loss_budget.o2} dB</span>
          </div>
          <div class="flex justify-between">
            <span>H&#8322;O Absorption</span>
            <span class="font-mono">{@result.loss_budget.h2o} dB</span>
          </div>
          <%= if @result.loss_budget.rain > 0 do %>
            <div class="flex justify-between">
              <span>Rain</span>
              <span class="font-mono">{@result.loss_budget.rain} dB</span>
            </div>
          <% end %>
          <%= if @result.loss_budget.diffraction > 0 do %>
            <div class="flex justify-between">
              <span>Diffraction</span>
              <span class="font-mono">{@result.loss_budget.diffraction} dB</span>
            </div>
          <% end %>
          <div class="divider my-1"></div>
          <div class="flex justify-between font-bold">
            <span>Total Path Loss</span>
            <span class="font-mono">{@result.loss_budget.total} dB</span>
          </div>
        </div>
      </div>

      <%!-- Propagation Score --%>
      <div class="bg-base-200 rounded-box p-4">
        <div class="text-xs opacity-60 mb-2">Propagation Score</div>
        <%= if @result.scoring do %>
          <div class="text-center mb-3">
            <span
              class="text-4xl font-bold"
              style={"color: #{tier_color(@result.scoring.score)}"}
            >
              {@result.scoring.score}
            </span>
            <span class="text-sm opacity-60"> / 100</span>
            <div
              class="text-sm font-semibold mt-1"
              style={"color: #{tier_color(@result.scoring.score)}"}
            >
              {tier_label(@result.scoring.score)}
            </div>
          </div>
        <% else %>
          <div class="text-center text-sm opacity-60 py-4">
            No HRRR data available for current conditions
          </div>
        <% end %>
      </div>
    </div>

    <%!-- Factor breakdown --%>
    <%= if @result.scoring do %>
      <div class="bg-base-200 rounded-box p-4 mb-6">
        <div class="text-xs opacity-60 mb-3">Propagation Factors (current conditions)</div>
        <.factor_table scoring={@result.scoring} />
      </div>
    <% end %>

    <%!-- Atmospheric conditions --%>
    <%= if @result.conditions do %>
      <div class="bg-base-200 rounded-box p-4 mb-6">
        <div class="text-xs opacity-60 mb-3">Path Atmospheric Conditions</div>
        <div class="grid grid-cols-2 md:grid-cols-4 gap-3 text-sm">
          <div>
            <span class="opacity-60">Temperature</span>
            <div class="font-mono">{format_number(@result.conditions.temp_c)}&deg;C</div>
          </div>
          <div>
            <span class="opacity-60">Dewpoint</span>
            <div class="font-mono">{format_number(@result.conditions.dewpoint_c)}&deg;C</div>
          </div>
          <div>
            <span class="opacity-60">T-Td Depression</span>
            <div class="font-mono">
              {format_number(@result.conditions.temp_c - @result.conditions.dewpoint_c)}&deg;C
            </div>
          </div>
          <div>
            <span class="opacity-60">Pressure</span>
            <div class="font-mono">{format_number(@result.conditions.pressure_mb || 0)} mb</div>
          </div>
          <div>
            <span class="opacity-60">PWAT</span>
            <div class="font-mono">{format_number(@result.conditions.pwat_mm || 0)} mm</div>
          </div>
          <div>
            <span class="opacity-60">BL Depth</span>
            <div class="font-mono">{format_number(@result.conditions.bl_depth_m || 0)} m</div>
          </div>
          <div>
            <span class="opacity-60">Refractivity Gradient</span>
            <div class="font-mono">
              {format_number(@result.conditions.min_refractivity_gradient || 0)} N/km
            </div>
          </div>
          <div>
            <span class="opacity-60">Abs Humidity</span>
            <div class="font-mono">{format_number(@result.conditions.abs_humidity)} g/m&sup3;</div>
          </div>
        </div>
      </div>
    <% end %>
    """
  end

  defp factor_table(assigns) do
    weights = BandConfig.weights()

    rows =
      assigns.scoring.factors
      |> Enum.map(fn {key, score} ->
        weight = Map.get(weights, key, 0)

        %{
          name: factor_name(key),
          score: score,
          weight: round(weight * 100),
          contribution: Float.round(score * weight, 1)
        }
      end)
      |> Enum.sort_by(& &1.contribution, :desc)

    assigns = assign(assigns, :rows, rows)

    ~H"""
    <table class="table table-sm">
      <thead>
        <tr>
          <th>Factor</th>
          <th class="text-right">Score</th>
          <th class="text-right">Weight</th>
          <th class="text-right">Contribution</th>
        </tr>
      </thead>
      <tbody>
        <%= for row <- @rows do %>
          <tr>
            <td>{row.name}</td>
            <td class="text-right font-mono">{row.score}</td>
            <td class="text-right font-mono opacity-60">{row.weight}%</td>
            <td class="text-right font-mono font-bold">{row.contribution}</td>
          </tr>
        <% end %>
      </tbody>
    </table>
    """
  end

  defp factor_name(:humidity), do: "Humidity"
  defp factor_name(:time_of_day), do: "Time of Day"
  defp factor_name(:td_depression), do: "T-Td Depression"
  defp factor_name(:refractivity), do: "Refractivity"
  defp factor_name(:sky), do: "Sky Cover"
  defp factor_name(:season), do: "Season"
  defp factor_name(:wind), do: "Wind"
  defp factor_name(:rain), do: "Rain"
  defp factor_name(:pwat), do: "PWAT"
  defp factor_name(:pressure), do: "Pressure"

  defp elevation_data(result) do
    points =
      Enum.map(result.terrain.analysis.points, fn p ->
        %{
          dist_km: p.dist_km,
          elev_m: p.elev,
          beam_m: p[:beam],
          fresnel_top: if(p[:beam] && p[:r1], do: p.beam + p.r1),
          fresnel_bottom: if(p[:beam] && p[:r1], do: p.beam - p.r1)
        }
      end)

    %{
      points: points,
      freq_mhz: result.band_mhz,
      dist_km: result.dist_km,
      verdict: result.terrain.analysis.verdict,
      ducts: []
    }
  end
end