opi-ai 0.3.0

//! Shared test utilities for mock-provider testing (task 1.17).
//!
//! Provides `MockProvider` for deterministic, fixture-based provider simulation
//! across all workspace crates. No live API calls.

use std::sync::{Arc, Mutex};

use crate::message::AssistantMessage;
use crate::provider::{EventStream, ModelInfo, Provider, ProviderError, Request};
use crate::stream::{AssistantStreamEvent, StopReason, Usage};

/// A response that a mock provider can return per `stream()` call.
#[doc(hidden)]
pub enum MockResponse {
    /// Successful stream of assistant events.
    Events(Vec<AssistantStreamEvent>),
    /// Provider error (e.g. rate-limited, timeout).
    Error(ProviderError),
}

/// A mock provider that returns pre-programmed response sequences.
///
/// Each call to `stream()` pops the next response from the queue.
/// Tracks call history for assertions.
#[doc(hidden)]
pub struct MockProvider {
    id: String,
    models: Vec<ModelInfo>,
    responses: Arc<Mutex<Vec<MockResponse>>>,
    call_log: Arc<Mutex<Vec<Request>>>,
}

impl MockProvider {
    /// Create a new mock provider with the given response sequences.
    ///
    /// Each element of `responses` is a complete batch of stream events
    /// returned by one `stream()` call. Batches are consumed in order.
    pub fn new(id: &str, responses: Vec<Vec<AssistantStreamEvent>>) -> Self {
        Self::new_with_errors(
            id,
            responses.into_iter().map(MockResponse::Events).collect(),
        )
    }

    /// Create a mock provider that can return errors between successful responses.
    pub fn new_with_errors(id: &str, responses: Vec<MockResponse>) -> Self {
        Self {
            id: id.to_owned(),
            models: vec![ModelInfo {
                id: "mock-model".into(),
                display_name: "Mock Model".into(),
                context_window: 100_000,
                max_output_tokens: 4_096,
                supports_streaming: true,
                supports_thinking: false,
            }],
            responses: Arc::new(Mutex::new(responses)),
            call_log: Arc::new(Mutex::new(Vec::new())),
        }
    }

    /// Number of times `stream()` has been called.
    pub fn stream_call_count(&self) -> usize {
        self.call_log.lock().unwrap().len()
    }

    /// Snapshot the `messages` field of every `Request` passed to `stream()`
    /// so far. Useful for asserting which messages the provider observed
    /// during a test run.
    pub fn recorded_messages(&self) -> Vec<Vec<crate::message::Message>> {
        self.call_log
            .lock()
            .unwrap()
            .iter()
            .map(|r| r.messages.clone())
            .collect()
    }

    /// Clone the shared call-log handle. Lets a test hold a reference to the
    /// recorded requests even after the provider is moved into a `Box<dyn
    /// Provider>`.
    pub fn call_log_handle(&self) -> Arc<Mutex<Vec<Request>>> {
        Arc::clone(&self.call_log)
    }
}

/// Helper: build a base `AssistantMessage` for fixture construction.
pub fn base_assistant() -> AssistantMessage {
    AssistantMessage {
        content: vec![],
        api: crate::ApiKind::Anthropic,
        provider: "mock".into(),
        model: "mock-model".into(),
        response_model: None,
        response_id: None,
        usage: Usage::default(),
        stop_reason: StopReason::Stop,
        error_message: None,
        timestamp_ms: 0,
    }
}

/// Helper: build a text-only response (Start → TextDelta → Done).
pub fn text_response(text: &str) -> Vec<AssistantStreamEvent> {
    let mut partial = base_assistant();
    partial
        .content
        .push(crate::message::AssistantContent::Text { text: text.into() });
    vec![
        AssistantStreamEvent::Start {
            partial: base_assistant(),
        },
        AssistantStreamEvent::TextDelta {
            content_index: 0,
            delta: text.into(),
            partial: partial.clone(),
        },
        AssistantStreamEvent::Done {
            reason: StopReason::Stop,
            message: partial,
        },
    ]
}

/// Helper: build a tool-call response (Start → ToolCallEnd → Done).
pub fn tool_call_response(
    tool_call_id: &str,
    tool_name: &str,
    arguments: &str,
) -> Vec<AssistantStreamEvent> {
    let tool_call = crate::message::ToolCall {
        id: tool_call_id.into(),
        name: tool_name.into(),
        arguments: arguments.into(),
    };
    let mut partial = base_assistant();
    partial
        .content
        .push(crate::message::AssistantContent::ToolCall {
            tool_call: tool_call.clone(),
        });
    vec![
        AssistantStreamEvent::Start {
            partial: base_assistant(),
        },
        AssistantStreamEvent::ToolCallEnd {
            content_index: 0,
            tool_call,
            partial: partial.clone(),
        },
        AssistantStreamEvent::Done {
            reason: StopReason::ToolUse,
            message: partial,
        },
    ]
}

/// Helper: build an error response (Start → Error).
pub fn error_response(error_message: &str) -> Vec<AssistantStreamEvent> {
    let mut partial = base_assistant();
    partial.error_message = Some(error_message.into());
    vec![
        AssistantStreamEvent::Start {
            partial: base_assistant(),
        },
        AssistantStreamEvent::Error {
            reason: StopReason::Error,
            message: partial,
        },
    ]
}

impl Provider for MockProvider {
    fn id(&self) -> &str {
        &self.id
    }

    fn models(&self) -> &[ModelInfo] {
        &self.models
    }

    fn stream(&self, request: Request) -> EventStream {
        self.call_log.lock().unwrap().push(request);
        let mut responses = self.responses.lock().unwrap();
        assert!(
            !responses.is_empty(),
            "MockProvider: stream() called more times than responses were configured"
        );
        let response = responses.remove(0);
        match response {
            MockResponse::Events(events) => {
                let stream =
                    futures_util::stream::iter(events.into_iter().map(Ok::<_, ProviderError>));
                Box::pin(stream)
            }
            MockResponse::Error(e) => {
                let stream = futures_util::stream::iter(vec![Err(e)]);
                Box::pin(stream)
            }
        }
    }
}