use agent_core::{create_event_channel, run_agent_loop_streaming, AgentEvent, ToolContext};
use async_trait::async_trait;
use futures_util::stream;
use llm_core::{
    ChatMessage, ChatOptions, LlmError, StreamChunk, LlmProvider, Tool, ToolCallDelta,
};
use permissions::{Mode, PermissionManager};
use std::pin::Pin;

/// Mock LLM provider for testing streaming
struct MockStreamingProvider {
    responses: Vec<MockResponse>,
}

enum MockResponse {
    /// Text-only response (no tool calls)
    Text(Vec<String>), // Chunks of text
    /// Tool call response
    ToolCall {
        text_chunks: Vec<String>,
        tool_id: String,
        tool_name: String,
        tool_args: String,
    },
}

#[async_trait]
impl LlmProvider for MockStreamingProvider {
    fn name(&self) -> &str {
        "mock"
    }

    fn model(&self) -> &str {
        "mock-model"
    }

    async fn chat_stream(
        &self,
        messages: &[ChatMessage],
        _options: &ChatOptions,
        _tools: Option<&[Tool]>,
    ) -> Result<Pin<Box<dyn futures_util::Stream<Item = Result<StreamChunk, LlmError>> + Send>>, LlmError> {
        // Determine which response to use based on message count
        let response_idx = (messages.len() / 2).min(self.responses.len() - 1);
        let response = &self.responses[response_idx];

        let chunks: Vec<Result<StreamChunk, LlmError>> = match response {
            MockResponse::Text(text_chunks) => text_chunks
                .iter()
                .map(|text| {
                    Ok(StreamChunk {
                        content: Some(text.clone()),
                        tool_calls: None,
                        done: false,
                        usage: None,
                    })
                })
                .collect(),
            MockResponse::ToolCall {
                text_chunks,
                tool_id,
                tool_name,
                tool_args,
            } => {
                let mut result = vec![];

                // First emit text chunks
                for text in text_chunks {
                    result.push(Ok(StreamChunk {
                        content: Some(text.clone()),
                        tool_calls: None,
                        done: false,
                        usage: None,
                    }));
                }

                // Then emit tool call in chunks
                result.push(Ok(StreamChunk {
                    content: None,
                    tool_calls: Some(vec![ToolCallDelta {
                        index: 0,
                        id: Some(tool_id.clone()),
                        function_name: Some(tool_name.clone()),
                        arguments_delta: None,
                    }]),
                    done: false,
                    usage: None,
                }));

                // Emit args in chunks
                for chunk in tool_args.chars().collect::<Vec<_>>().chunks(5) {
                    result.push(Ok(StreamChunk {
                        content: None,
                        tool_calls: Some(vec![ToolCallDelta {
                            index: 0,
                            id: None,
                            function_name: None,
                            arguments_delta: Some(chunk.iter().collect()),
                        }]),
                        done: false,
                        usage: None,
                    }));
                }

                result
            }
        };

        Ok(Box::pin(stream::iter(chunks)))
    }
}

#[tokio::test]
async fn test_streaming_text_only() {
    let provider = MockStreamingProvider {
        responses: vec![MockResponse::Text(vec![
            "Hello".to_string(),
            " ".to_string(),
            "world".to_string(),
            "!".to_string(),
        ])],
    };

    let perms = PermissionManager::new(Mode::Plan);
    let ctx = ToolContext::default();
    let (tx, mut rx) = create_event_channel();

    // Spawn the agent loop
    let handle = tokio::spawn(async move {
        run_agent_loop_streaming(
            &provider,
            "Say hello",
            &ChatOptions::default(),
            &perms,
            &ctx,
            tx,
        )
        .await
    });

    // Collect events
    let mut text_deltas = vec![];
    let mut done_response = None;

    while let Some(event) = rx.recv().await {
        match event {
            AgentEvent::TextDelta(text) => {
                text_deltas.push(text);
            }
            AgentEvent::Done { final_response } => {
                done_response = Some(final_response);
                break;
            }
            AgentEvent::Error(e) => {
                panic!("Unexpected error: {}", e);
            }
            _ => {}
        }
    }

    // Wait for agent loop to complete
    let result = handle.await.unwrap();
    assert!(result.is_ok());

    // Verify events
    assert_eq!(text_deltas, vec!["Hello", " ", "world", "!"]);
    assert_eq!(done_response, Some("Hello world!".to_string()));
    assert_eq!(result.unwrap(), "Hello world!");
}

#[tokio::test]
async fn test_streaming_with_tool_call() {
    let provider = MockStreamingProvider {
        responses: vec![
            MockResponse::ToolCall {
                text_chunks: vec!["Let me ".to_string(), "check...".to_string()],
                tool_id: "call_123".to_string(),
                tool_name: "glob".to_string(),
                tool_args: r#"{"pattern":"*.rs"}"#.to_string(),
            },
            MockResponse::Text(vec!["Found ".to_string(), "the files!".to_string()]),
        ],
    };

    let perms = PermissionManager::new(Mode::Plan);
    let ctx = ToolContext::default();
    let (tx, mut rx) = create_event_channel();

    // Spawn the agent loop
    let handle = tokio::spawn(async move {
        run_agent_loop_streaming(
            &provider,
            "Find Rust files",
            &ChatOptions::default(),
            &perms,
            &ctx,
            tx,
        )
        .await
    });

    // Collect events
    let mut text_deltas = vec![];
    let mut tool_starts = vec![];
    let mut tool_outputs = vec![];
    let mut tool_ends = vec![];

    while let Some(event) = rx.recv().await {
        match event {
            AgentEvent::TextDelta(text) => {
                text_deltas.push(text);
            }
            AgentEvent::ToolStart {
                tool_name,
                tool_id,
            } => {
                tool_starts.push((tool_name, tool_id));
            }
            AgentEvent::ToolOutput {
                tool_id,
                content,
                is_error,
            } => {
                tool_outputs.push((tool_id, content, is_error));
            }
            AgentEvent::ToolEnd { tool_id, success } => {
                tool_ends.push((tool_id, success));
            }
            AgentEvent::Done { .. } => {
                break;
            }
            AgentEvent::Error(e) => {
                panic!("Unexpected error: {}", e);
            }
        }
    }

    // Wait for agent loop to complete
    let result = handle.await.unwrap();
    assert!(result.is_ok());

    // Verify we got text deltas from both responses
    assert!(text_deltas.contains(&"Let me ".to_string()));
    assert!(text_deltas.contains(&"check...".to_string()));
    assert!(text_deltas.contains(&"Found ".to_string()));
    assert!(text_deltas.contains(&"the files!".to_string()));

    // Verify tool events
    assert_eq!(tool_starts.len(), 1);
    assert_eq!(tool_starts[0].0, "glob");
    assert_eq!(tool_starts[0].1, "call_123");

    assert_eq!(tool_outputs.len(), 1);
    assert_eq!(tool_outputs[0].0, "call_123");
    assert!(!tool_outputs[0].2); // not an error

    assert_eq!(tool_ends.len(), 1);
    assert_eq!(tool_ends[0].0, "call_123");
    assert!(tool_ends[0].1); // success
}

#[tokio::test]
async fn test_channel_creation() {
    let (tx, mut rx) = create_event_channel();

    // Test that channel works
    tx.send(AgentEvent::TextDelta("test".to_string()))
        .await
        .unwrap();

    let event = rx.recv().await.unwrap();
    match event {
        AgentEvent::TextDelta(text) => assert_eq!(text, "test"),
        _ => panic!("Wrong event type"),
    }
}