# `Monitorex.EventHandler`

Handles telemetry events from Tesla, Finch, and Phoenix, transforming them
into `Monitorex.Event` structs.

Each handler function follows the `Telemetry` handler callback signature:
`(event_name, measurements, metadata, config)`.

# `handle_finch_event`

```elixir
@spec handle_finch_event(
  event_name :: [atom()],
  measurements :: map(),
  metadata :: map(),
  config :: keyword()
) :: Monitorex.Event.t() | nil
```

Handles a Finch telemetry event (`[:finch, :request, :stop]`).

Parses the metadata and measurements into a `Monitorex.Event` struct with
source `:finch` and direction `:outbound`.

## Telemetry metadata shape

    %{
      url:  %URI{} | String.t(),
      method: :get | "GET" | …,
      status: 200,
      pid: pid,
      monotonic_time: integer
    }

The `url` field may be a `URI.t()` struct or a string; both are handled.
The `method` field may be an atom or string; both are normalised.

# `handle_phoenix_event`

```elixir
@spec handle_phoenix_event(
  event_name :: [atom()],
  measurements :: map(),
  metadata :: map(),
  config :: keyword()
) :: Monitorex.Event.t() | nil
```

Handles a Phoenix telemetry event (`[:phoenix, :router_dispatch, :stop]`).

Parses the metadata and measurements into a `Monitorex.Event` struct with
source `:phoenix` and direction `:inbound`.

The consumer is extracted via `ConsumerIdentifier.identify/1`.

If the application config key `:inbound_path_prefixes` is set to a list of
path prefixes, only requests whose path starts with one of the prefixes
produce an event.  Returns `nil` (i.e. the event is filtered) when no
prefix matches.

## Telemetry metadata shape

    %{
      conn: %Plug.Conn{}
    }

# `handle_tesla_event`

```elixir
@spec handle_tesla_event(
  event_name :: [atom()],
  measurements :: map(),
  metadata :: map(),
  config :: keyword()
) :: Monitorex.Event.t() | nil
```

Handles a Tesla telemetry event (`[:tesla, :request, :stop]`).

Parses the metadata and measurements into a `Monitorex.Event` struct with
source `:tesla` and direction `:outbound`.

The URL is normalised via `UrlNormalizer.normalize/1` and sensitive query
parameters are redacted via `URLRedactor.redact/1`.

## Telemetry metadata shape

    %{
      url:  %URI{},
      method: :get | :post | …,
      status: 200,
      pid: pid,
      monotonic_time: integer
    }

The `dedup_key` is set to `{pid, monotonic_time}` for deduplication.

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*Consult [api-reference.md](api-reference.md) for complete listing*