systemprompt-api 0.10.3

//! Streaming-event accumulation: folds canonical SSE events into a `TapState`
//! and extracts a finalized `Summary` for the audit sink.

use bytes::{Bytes, BytesMut};

use super::super::captures::{CapturedToolUse, CapturedUsage};
use super::super::protocol::canonical::CanonicalContent;
use super::super::protocol::canonical_response::{
    CanonicalEvent, CanonicalResponse, CanonicalStopReason, CanonicalUsage, ContentBlockKind,
};

#[derive(Default)]
pub(super) struct TapState {
    response_id: String,
    served_model: String,
    usage: CanonicalUsage,
    blocks: Vec<BlockAccumulator>,
    final_stop_reason: Option<CanonicalStopReason>,
    pub(super) final_bytes: BytesMut,
    pub(super) error: Option<String>,
    pub(super) finalized: bool,
}

#[derive(Clone)]
enum BlockAccumulator {
    Text(String),
    Thinking {
        text: String,
        signature: Option<String>,
    },
    ToolUse {
        id: String,
        name: String,
        partial: String,
    },
}

pub(super) struct Summary {
    pub(super) usage: CapturedUsage,
    pub(super) tool_calls: Vec<CapturedToolUse>,
    pub(super) response: CanonicalResponse,
    pub(super) final_bytes: Bytes,
    pub(super) served_model: Option<String>,
    pub(super) error: Option<String>,
    pub(super) saw_stop: bool,
}

pub(super) fn extract_summary(state: &mut TapState) -> Summary {
    let response = build_response(state);
    let usage = CapturedUsage {
        input_tokens: state.usage.input_tokens,
        output_tokens: state.usage.output_tokens,
    };
    let tool_calls = response
        .content
        .iter()
        .filter_map(|c| {
            if let CanonicalContent::ToolUse { id, name, input } = c {
                Some(CapturedToolUse {
                    ai_tool_call_id: id.clone(),
                    tool_name: name.clone(),
                    tool_input: serde_json::to_string(input).unwrap_or_else(|e| {
                        tracing::warn!(error = %e, tool = %name, "failed to serialise tool_input");
                        String::new()
                    }),
                })
            } else {
                None
            }
        })
        .collect();
    let final_bytes = std::mem::take(&mut state.final_bytes).freeze();
    let served_model = if state.served_model.is_empty() {
        None
    } else {
        Some(state.served_model.clone())
    };
    Summary {
        usage,
        tool_calls,
        response,
        final_bytes,
        served_model,
        error: state.error.clone(),
        saw_stop: state.final_stop_reason.is_some(),
    }
}

fn build_response(state: &TapState) -> CanonicalResponse {
    let content = state
        .blocks
        .iter()
        .map(|b| match b {
            BlockAccumulator::Text(t) => CanonicalContent::Text(t.clone()),
            BlockAccumulator::Thinking { text, signature } => CanonicalContent::Thinking {
                text: text.clone(),
                signature: signature.clone(),
            },
            BlockAccumulator::ToolUse { id, name, partial } => CanonicalContent::ToolUse {
                id: id.clone(),
                name: name.clone(),
                input: serde_json::from_str(partial)
                    .unwrap_or(serde_json::Value::Object(serde_json::Map::new())),
            },
        })
        .collect();
    CanonicalResponse {
        id: state.response_id.clone(),
        model: state.served_model.clone(),
        content,
        stop_reason: state.final_stop_reason,
        usage: state.usage,
    }
}

pub(super) fn accumulate_event(state: &mut TapState, event: &CanonicalEvent) {
    match event {
        CanonicalEvent::MessageStart { id, model, usage } => {
            state.response_id.clone_from(id);
            if !model.is_empty() {
                state.served_model.clone_from(model);
            }
            state.usage = *usage;
        },
        CanonicalEvent::ContentBlockStart { index, block } => {
            let slot = match block {
                ContentBlockKind::Text => BlockAccumulator::Text(String::new()),
                ContentBlockKind::Thinking { signature } => BlockAccumulator::Thinking {
                    text: String::new(),
                    signature: signature.clone(),
                },
                ContentBlockKind::ToolUse { id, name } => BlockAccumulator::ToolUse {
                    id: id.clone(),
                    name: name.clone(),
                    partial: String::new(),
                },
            };
            let idx = *index as usize;
            while state.blocks.len() <= idx {
                state.blocks.push(BlockAccumulator::Text(String::new()));
            }
            state.blocks[idx] = slot;
        },
        CanonicalEvent::TextDelta { index, text } => {
            if let Some(BlockAccumulator::Text(buf)) = state.blocks.get_mut(*index as usize) {
                buf.push_str(text);
            }
        },
        CanonicalEvent::ThinkingDelta { index, text } => {
            if let Some(BlockAccumulator::Thinking { text: buf, .. }) =
                state.blocks.get_mut(*index as usize)
            {
                buf.push_str(text);
            }
        },
        CanonicalEvent::ToolUseDelta {
            index,
            partial_json,
        } => {
            if let Some(BlockAccumulator::ToolUse { partial, .. }) =
                state.blocks.get_mut(*index as usize)
            {
                partial.push_str(partial_json);
            }
        },
        CanonicalEvent::ContentBlockStop { .. } => {},
        CanonicalEvent::UsageDelta(u) => {
            if u.input_tokens > 0 {
                state.usage.input_tokens = u.input_tokens;
            }
            if u.output_tokens > 0 {
                state.usage.output_tokens = u.output_tokens;
            }
        },
        CanonicalEvent::MessageStop { stop_reason, .. } => {
            state.final_stop_reason = stop_reason.or(Some(CanonicalStopReason::EndTurn));
        },
        CanonicalEvent::Error(msg) => {
            state.error = Some(msg.clone());
        },
    }
}