posthog-rs 0.19.1

//! Shared, runtime-agnostic helpers for the V0 capture pipeline.
//! Each client keeps only the I/O; this module owns event preparation and
//! payload construction.

// The transport worker is always blocking reqwest, even for the async client,
// so the v0 request helpers operate on the blocking RequestBuilder.
use chrono::{DateTime, Utc};
use reqwest::blocking::RequestBuilder;

use super::{
    common::{apply_before_send_hooks, apply_capture_defaults, apply_runtime_context},
    BeforeSendHook, CaptureDefaults, ClientOptions,
};
use crate::endpoints::Endpoint;
use crate::error::Error;
use crate::event::{BatchRequest, Event, InnerEvent};

// ---------------------------------------------------------------------------
// Event preparation
// ---------------------------------------------------------------------------

/// Apply client-level default properties (caller-wins) and V0 metadata stamping.
///
/// Uses `insert_prop_default` so a caller who explicitly set a property on the
/// event before calling `capture()` keeps their value.
pub(crate) fn prepare_event(event: &mut Event, defaults: &CaptureDefaults) {
    apply_capture_defaults(event, defaults);
    apply_runtime_context(event);
    event.prepare_for_v0();
}

// ---------------------------------------------------------------------------
// Payload building
// ---------------------------------------------------------------------------

/// Build the JSON body for a V0 batch capture request.
///
/// Returns the serialized body together with the number of events that survived
/// `before_send` filtering, so the caller can account for filtered-out events as
/// terminal and track only what is actually in flight. `Ok(None)` means every
/// event was dropped by `before_send`.
pub(crate) fn build_batch_payload(
    events: Vec<Event>,
    api_key: String,
    historical_migration: bool,
    sent_at: DateTime<Utc>,
    defaults: &CaptureDefaults,
    before_send: &[BeforeSendHook],
) -> Result<Option<(String, usize)>, Error> {
    let inner_events: Vec<InnerEvent> = events
        .into_iter()
        .filter_map(|mut event| {
            prepare_event(&mut event, defaults);
            apply_before_send_hooks(before_send, event).map(InnerEvent::new_for_batch)
        })
        .collect();

    if inner_events.is_empty() {
        return Ok(None);
    }

    let kept = inner_events.len();
    let batch_request = BatchRequest {
        api_key,
        historical_migration,
        sent_at: sent_at.to_rfc3339(),
        batch: inner_events,
    };
    serde_json::to_string(&batch_request)
        .map(|json| Some((json, kept)))
        .map_err(|e| Error::Serialization(e.to_string()))
}

/// Encode the V0 JSON body, compressing when configured. Returns the bytes and
/// the `Content-Encoding` token to advertise (`Some(token)` when compressed,
/// `None` when sent uncompressed). Routes through the shared `compress()`, so a
/// V0 build is gzip-only by construction; a non-gzip algorithm or a compression
/// failure falls back to uncompressed.
pub(crate) fn encode_body(
    options: &ClientOptions,
    json: String,
) -> (Vec<u8>, Option<&'static str>) {
    match options.capture_compression {
        Some(algo) => match crate::compression::compress(algo, json.as_bytes()) {
            Some((bytes, encoding)) => (bytes, Some(encoding)),
            None => (json.into_bytes(), None),
        },
        None => (json.into_bytes(), None),
    }
}

// ---------------------------------------------------------------------------
// Inline (immediate) capture preparation
// ---------------------------------------------------------------------------

/// Everything an inline immediate V0 capture needs after payload building: the
/// target URL (already carrying the `?compression=` query param when compressed),
/// the encoded body, the `Content-Encoding` token to advertise, and the number
/// of events kept after `before_send`. I/O-free, so both clients share it.
pub(crate) struct PreparedV0 {
    pub(crate) url: String,
    pub(crate) body: Vec<u8>,
    pub(crate) encoding: Option<&'static str>,
    pub(crate) kept: usize,
}

/// Prepare an inline immediate V0 capture: build the batch payload (applying
/// defaults + `before_send`), encode/compress it, and resolve the target URL.
/// Returns `Ok(None)` when every event was dropped by `before_send`, so the
/// caller returns a default summary without sending.
pub(crate) fn prepare_immediate(
    options: &ClientOptions,
    events: Vec<Event>,
    historical_migration: bool,
) -> Result<Option<PreparedV0>, Error> {
    let defaults = options.capture_defaults();
    let Some((json, kept)) = build_batch_payload(
        events,
        options.api_key.clone(),
        historical_migration,
        Utc::now(),
        &defaults,
        &options.before_send,
    )?
    else {
        return Ok(None);
    };

    let base_url = options.endpoints().build_url(Endpoint::Batch);
    let (body, encoding) = encode_body(options, json);
    // v0 capture reads the compression hint from the query param, not the header.
    let url = match encoding {
        Some(token) => format!("{base_url}?compression={token}"),
        None => base_url,
    };
    Ok(Some(PreparedV0 {
        url,
        body,
        encoding,
        kept,
    }))
}

// ---------------------------------------------------------------------------
// Header helpers
// ---------------------------------------------------------------------------

/// Apply test-harness extra headers to a V0 request.
pub(crate) fn apply_extra_headers(
    #[allow(unused_variables)] options: &ClientOptions,
    #[allow(unused_mut)] mut request: RequestBuilder,
) -> RequestBuilder {
    #[cfg(feature = "test-harness")]
    if let Some(ref extra) = options.extra_capture_headers {
        for (k, v) in extra {
            request = request.header(k.as_str(), v.as_str());
        }
    }
    request
}