# Compiled only when {:mux, "~> 3.2"} is loaded.
# Adopters who do not configure streaming pay zero transitive cost.
if Code.ensure_loaded?(Mux.Video.Assets) do
  defmodule Rindle.Workers.MuxSyncProviderAsset do
    @moduledoc """
    Per-row defensive sync for `media_provider_assets` rows that may have
    missed a webhook. Called by `Rindle.Workers.MuxSyncCoordinator` (Phase 34
    ships the cron coordinator; Phase 35 wires up webhook-driven sync).

    ## Job Arguments

        %{"provider_asset_id" => mux_asset_id}

    ## Behavior

      1. Fetch row by `provider_asset_id`.
      2. If the row is past the stuck threshold, transition to `:errored`
         with `last_sync_error: "stuck in :<state> past threshold"` and emit
         `[:rindle, :provider, :sync, :stuck]`.
      3. Otherwise, call `Rindle.Streaming.Provider.Mux.get_asset/1` and
         reconcile FSM/playback_ids. Emit `[:rindle, :provider, :sync, :resolved]`.
      4. If Mux returns 404, transition to `:errored` with reason
         `"mux asset not found"` and emit `:resolved` (the row IS now reconciled
         with reality — there is no asset to wait for).

    ## Telemetry Contract

      * `[:rindle, :provider, :sync, :resolved]` — fires on every successful
        `get_asset/1` call (whether or not a state change occurred).

            measurements: %{system_time}
            metadata:     %{profile, provider, asset_id, provider_state, age_ms, no_change}

      * `[:rindle, :provider, :sync, :stuck]` — fires when the row's
        `updated_at` exceeds `:provider_stuck_threshold_seconds` (default 7200).
        Same metadata shape; `provider_state` reflects the row's final
        `:errored` state.

    `metadata.asset_id` is the redacted last-4-char tag of the
    `provider_asset_id` (security invariant 14, via
    `Rindle.Domain.MediaProviderAsset.redact_id/1`).

    ### `age_ms` semantics across `:resolved` and `:stuck` (WR-03 / POLISH-01/D-13)

    `metadata.age_ms` is ALWAYS "time since the row's `updated_at`", never
    "time since the last sync attempt". Because a no-op `:resolved` event
    (live state already matches the row — see `metadata.no_change: true`)
    performs no DB write, `updated_at` is unchanged and `age_ms` keeps growing
    while syncs are succeeding. The same metric therefore carries two
    operational semantics depending on the event/branch:

      * `:resolved` with `no_change: false` — a transition just happened, so
        `age_ms` measures the age of the row *before* this sync resolved it.
      * `:resolved` with `no_change: true` — nothing changed, so `age_ms`
        reflects "time since the last actual state change", which legitimately
        balloons even though sync is healthy. Dashboards MUST gate on
        `no_change` (or use `:stuck`) before treating a large `age_ms` as a
        liveness problem.
      * `:stuck` — `age_ms` IS the threshold-driving liveness metric (the row
        exceeded `:provider_stuck_threshold_seconds`).

    Filter `:resolved` events by `no_change` before alerting on `age_ms`; the
    `:stuck` event is the canonical staleness signal.
    """

    use Oban.Worker, queue: :rindle_provider, max_attempts: 3

    alias Rindle.Domain.{MediaProviderAsset, ProviderAssetFSM}

    @default_stuck_threshold_seconds 7200

    @spec perform(Oban.Job.t()) :: :ok | {:error, term()}
    @impl Oban.Worker
    def perform(%Oban.Job{args: %{"provider_asset_id" => provider_asset_id}})
        when is_binary(provider_asset_id) do
      repo = Rindle.Config.repo()

      case repo.get_by(MediaProviderAsset, provider_asset_id: provider_asset_id) do
        nil ->
          # Row was deleted between coordinator scan and per-row execution.
          :ok

        row ->
          if stuck?(row) do
            mark_stuck(repo, row)
          else
            sync_with_provider(repo, row)
          end
      end
    end

    # ============================================================
    # Stuck-threshold check + transition to :errored
    # ============================================================

    defp stuck?(row) do
      threshold = config(:provider_stuck_threshold_seconds, @default_stuck_threshold_seconds)
      age = age_seconds(row.updated_at)
      row.state in ["processing", "uploading"] and age > threshold
    end

    # Schema `timestamps()` produces `:naive_datetime` by default; coerce to a
    # DateTime in UTC so `DateTime.diff/3` accepts it. Adopters may run with
    # `:utc_datetime` columns too — handle both shapes safely.
    defp age_seconds(%DateTime{} = ts), do: DateTime.diff(DateTime.utc_now(), ts, :second)

    defp age_seconds(%NaiveDateTime{} = ts) do
      DateTime.diff(DateTime.utc_now(), DateTime.from_naive!(ts, "Etc/UTC"), :second)
    end

    defp age_ms(%DateTime{} = ts), do: DateTime.diff(DateTime.utc_now(), ts, :millisecond)

    defp age_ms(%NaiveDateTime{} = ts) do
      DateTime.diff(DateTime.utc_now(), DateTime.from_naive!(ts, "Etc/UTC"), :millisecond)
    end

    defp mark_stuck(repo, row) do
      reason = "stuck in :#{row.state} past threshold"
      profile_atom = String.to_existing_atom(row.profile)

      # B4 fix: third arg is a MAP, not a keyword list (provider_asset_fsm.ex:28).
      with :ok <-
             ProviderAssetFSM.transition(row.state, "errored", %{
               profile: profile_atom,
               provider: :mux,
               asset_id: row.asset_id
             }),
           {:ok, updated} <-
             row
             |> MediaProviderAsset.changeset(%{state: "errored", last_sync_error: reason})
             |> repo.update() do
        emit_sync_event(:stuck, updated, profile_atom)
        :ok
      end
    end

    # ============================================================
    # Per-row sync against live Mux state
    # ============================================================

    defp sync_with_provider(repo, row) do
      adapter = Rindle.Streaming.Provider.Mux

      case adapter.get_asset(row.provider_asset_id) do
        {:ok, %{state: live_state, playback_ids: pids, raw: _raw}} ->
          apply_state_transition(repo, row, live_state, pids)

        {:error, :not_found} ->
          # Mux deleted the asset; transition to :errored.
          profile_atom = String.to_existing_atom(row.profile)

          reconcile_to_errored(repo, row, profile_atom, "mux asset not found")

        {:error, reason} ->
          error_str = inspect(reason) |> String.slice(0, 4096)

          row
          |> MediaProviderAsset.changeset(%{last_sync_error: error_str})
          |> repo.update()

          {:error, reason}
      end
    end

    defp reconcile_to_errored(repo, row, profile_atom, reason) do
      with :ok <-
             ProviderAssetFSM.transition(row.state, "errored", %{
               profile: profile_atom,
               provider: :mux,
               asset_id: row.asset_id
             }),
           {:ok, updated} <-
             row
             |> MediaProviderAsset.changeset(%{
               state: "errored",
               last_sync_error: reason
             })
             |> repo.update() do
        emit_sync_event(:resolved, updated, profile_atom)
        :ok
      end
    end

    # B1 fix: persist `playback_ids` (PLURAL ARRAY) — schema field is
    # `field :playback_ids, {:array, :string}`. Write the list verbatim.
    defp apply_state_transition(repo, row, live_state, playback_ids) do
      profile_atom = String.to_existing_atom(row.profile)

      if live_state == row.state do
        # No transition needed; just emit :resolved with current state.
        emit_sync_event(:resolved, row, profile_atom, no_change: true)
        :ok
      else
        # Always persist the live PLURAL playback_ids list. The adapter
        # contract (`get_asset/1`) guarantees `playback_ids` is a list
        # (never nil) — `extract_playback_id_strings/1` returns [] on
        # missing or malformed payloads.
        attrs = %{
          state: live_state,
          playback_ids: playback_ids
        }

        case ProviderAssetFSM.transition(row.state, live_state, %{
               profile: profile_atom,
               provider: :mux,
               asset_id: row.asset_id
             }) do
          :ok ->
            case row |> MediaProviderAsset.changeset(attrs) |> repo.update() do
              {:ok, updated} ->
                emit_sync_event(:resolved, updated, profile_atom)
                :ok

              {:error, _} = err ->
                err
            end

          {:error, {:invalid_transition, from, to}} ->
            reconcile_to_errored(
              repo,
              row,
              profile_atom,
              "live state #{to} not reachable from #{from}"
            )

          err ->
            err
        end
      end
    end

    # ============================================================
    # Telemetry — security invariant 14 redaction at every emit.
    # ============================================================

    defp emit_sync_event(stage, row, profile, opts \\ []) do
      :telemetry.execute(
        [:rindle, :provider, :sync, stage],
        %{system_time: System.system_time()},
        %{
          profile: profile,
          provider: :mux,
          asset_id: MediaProviderAsset.redact_id(row.provider_asset_id),
          provider_state: row.state,
          age_ms: age_ms(row.updated_at),
          no_change: Keyword.get(opts, :no_change, false)
        }
      )
    end

    defp config(key, default) do
      :rindle
      |> Application.get_env(Rindle.Streaming.Provider.Mux, [])
      |> Keyword.get(key, default)
    end
  end
end