reson-agentic 0.5.1

//! Message conversion utilities
//!
//! Converts mixed ChatMessage/ToolResult/ToolCall/ReasoningSegment lists to provider-specific formats.
//! Handles message coalescing for Anthropic/Google providers.

use crate::error::Result;
use crate::types::{
    ChatMessage, ChatRole, MediaPart, MediaSource, MultimodalMessage, Provider, ReasoningSegment,
    ToolCall, ToolResult, VideoMetadata,
};
use serde_json::{json, Value};
use uuid::Uuid;

/// Message type that can appear in conversation history
#[derive(Debug, Clone, serde::Serialize)]
pub enum ConversationMessage {
    /// Regular chat message (user, assistant, system)
    Chat(ChatMessage),
    /// Tool call from the assistant
    ToolCall(ToolCall),
    /// Tool result from execution
    ToolResult(ToolResult),
    /// Reasoning/thinking segment
    Reasoning(ReasoningSegment),
    /// Multimodal message with media parts (images, video, audio)
    Multimodal(MultimodalMessage),
}

impl From<ChatMessage> for ConversationMessage {
    fn from(msg: ChatMessage) -> Self {
        ConversationMessage::Chat(msg)
    }
}

impl From<ToolCall> for ConversationMessage {
    fn from(tool_call: ToolCall) -> Self {
        ConversationMessage::ToolCall(tool_call)
    }
}

impl From<ToolResult> for ConversationMessage {
    fn from(result: ToolResult) -> Self {
        ConversationMessage::ToolResult(result)
    }
}

impl From<ReasoningSegment> for ConversationMessage {
    fn from(segment: ReasoningSegment) -> Self {
        ConversationMessage::Reasoning(segment)
    }
}

impl From<MultimodalMessage> for ConversationMessage {
    fn from(msg: MultimodalMessage) -> Self {
        ConversationMessage::Multimodal(msg)
    }
}

/// Convert a MediaPart to Google's parts format
pub fn media_part_to_google_format(part: &MediaPart, metadata: Option<&VideoMetadata>) -> Value {
    match part {
        MediaPart::Text { text } => json!({ "text": text }),

        MediaPart::Image { source, .. } => media_source_to_google_format(source, None),

        MediaPart::Audio { source, .. } => media_source_to_google_format(source, None),

        MediaPart::Video {
            source,
            metadata: video_meta,
        } => {
            let meta = video_meta.as_ref().or(metadata);
            media_source_to_google_format(source, meta)
        }

        MediaPart::Document { source } => media_source_to_google_format(source, None),
    }
}

/// Convert a MediaSource to Google's format
fn media_source_to_google_format(source: &MediaSource, metadata: Option<&VideoMetadata>) -> Value {
    let mut part = match source {
        MediaSource::Base64 { data, mime_type } => {
            json!({
                "inline_data": {
                    "data": data,
                    "mime_type": mime_type
                }
            })
        }
        MediaSource::Url { url } => {
            // Google doesn't support arbitrary URLs directly - must use file_data
            // This is a fallback that may not work for all cases
            json!({
                "file_data": {
                    "file_uri": url
                }
            })
        }
        MediaSource::FileId { file_id } => {
            json!({
                "file_data": {
                    "file_uri": file_id
                }
            })
        }
        MediaSource::FileUri { uri, mime_type } => {
            let mut fd = json!({
                "file_data": {
                    "file_uri": uri
                }
            });
            if let Some(mt) = mime_type {
                fd["file_data"]["mime_type"] = json!(mt);
            }
            fd
        }
    };

    // Add video metadata if present
    if let Some(meta) = metadata {
        let mut video_metadata = json!({});
        if let Some(ref start) = meta.start_offset {
            video_metadata["start_offset"] = json!(start);
        }
        if let Some(ref end) = meta.end_offset {
            video_metadata["end_offset"] = json!(end);
        }
        if let Some(fps) = meta.fps {
            video_metadata["fps"] = json!(fps);
        }
        if video_metadata
            .as_object()
            .map(|o| !o.is_empty())
            .unwrap_or(false)
        {
            part["video_metadata"] = video_metadata;
        }
    }

    part
}

/// Convert a MediaPart to Anthropic's content format
fn media_part_to_anthropic_format(part: &MediaPart) -> Value {
    match part {
        MediaPart::Text { text } => json!({
            "type": "text",
            "text": text
        }),

        MediaPart::Image { source, .. } => match source {
            MediaSource::Base64 { data, mime_type } => json!({
                "type": "image",
                "source": {
                    "type": "base64",
                    "media_type": mime_type,
                    "data": data
                }
            }),
            MediaSource::Url { url } => json!({
                "type": "image",
                "source": {
                    "type": "url",
                    "url": url
                }
            }),
            MediaSource::FileId { file_id } => json!({
                "type": "image",
                "source": {
                    "type": "file",
                    "file_id": file_id
                }
            }),
            MediaSource::FileUri { uri, .. } => json!({
                "type": "image",
                "source": {
                    "type": "url",
                    "url": uri
                }
            }),
        },

        MediaPart::Document { source } => match source {
            MediaSource::Base64 { data, mime_type } => json!({
                "type": "document",
                "source": {
                    "type": "base64",
                    "media_type": mime_type,
                    "data": data
                }
            }),
            MediaSource::FileId { file_id } => json!({
                "type": "document",
                "source": {
                    "type": "file",
                    "file_id": file_id
                }
            }),
            _ => json!({
                "type": "text",
                "text": "[Unsupported document source for Anthropic]"
            }),
        },

        // Anthropic doesn't support audio/video directly
        MediaPart::Audio { .. } | MediaPart::Video { .. } => json!({
            "type": "text",
            "text": "[Audio/Video not supported by this provider]"
        }),
    }
}

/// Convert a MediaPart to OpenAI's content format
fn media_part_to_openai_format(part: &MediaPart) -> Value {
    match part {
        MediaPart::Text { text } => json!({
            "type": "text",
            "text": text
        }),

        MediaPart::Image { source, detail } => {
            let mut img = match source {
                MediaSource::Base64 { data, mime_type } => json!({
                    "type": "image_url",
                    "image_url": {
                        "url": format!("data:{};base64,{}", mime_type, data)
                    }
                }),
                MediaSource::Url { url } => json!({
                    "type": "image_url",
                    "image_url": {
                        "url": url
                    }
                }),
                MediaSource::FileId { file_id } => json!({
                    "type": "image_file",
                    "image_file": {
                        "file_id": file_id
                    }
                }),
                MediaSource::FileUri { uri, .. } => json!({
                    "type": "image_url",
                    "image_url": {
                        "url": uri
                    }
                }),
            };
            if let Some(d) = detail {
                if let Some(obj) = img.get_mut("image_url") {
                    obj["detail"] = json!(d);
                }
            }
            img
        }

        MediaPart::Audio { source, format } => match source {
            MediaSource::Base64 { data, .. } => {
                let fmt = format.as_deref().unwrap_or("wav");
                json!({
                    "type": "input_audio",
                    "input_audio": {
                        "data": data,
                        "format": fmt
                    }
                })
            }
            _ => json!({
                "type": "text",
                "text": "[Unsupported audio source for OpenAI - use base64]"
            }),
        },

        // Video URL support (vLLM-compatible format for Qwen2-VL, etc.)
        MediaPart::Video {
            source: MediaSource::Url { url },
            ..
        } => json!({
            "type": "video_url",
            "video_url": { "url": url }
        }),
        MediaPart::Video { .. } | MediaPart::Document { .. } => json!({
            "type": "text",
            "text": "[Video/Document not supported by this provider]"
        }),
    }
}

/// Convert a MediaPart to OpenAI Responses API format
fn media_part_to_openai_responses_format(part: &MediaPart) -> Value {
    match part {
        MediaPart::Text { text } => json!({
            "type": "input_text",
            "text": text
        }),

        MediaPart::Image { source, .. } => match source {
            MediaSource::Base64 { data, mime_type } => json!({
                "type": "input_image",
                "image_url": {
                    "url": format!("data:{};base64,{}", mime_type, data)
                }
            }),
            MediaSource::Url { url } => json!({
                "type": "input_image",
                "image_url": {
                    "url": url
                }
            }),
            MediaSource::FileId { file_id } => json!({
                "type": "input_image",
                "image_file": {
                    "file_id": file_id
                }
            }),
            MediaSource::FileUri { uri, .. } => json!({
                "type": "input_image",
                "image_url": {
                    "url": uri
                }
            }),
        },

        MediaPart::Audio { source, format } => match source {
            MediaSource::Base64 { data, .. } => {
                let fmt = format.as_deref().unwrap_or("wav");
                json!({
                    "type": "input_audio",
                    "input_audio": {
                        "data": data,
                        "format": fmt
                    }
                })
            }
            _ => json!({
                "type": "input_text",
                "text": "[Unsupported audio source for OpenAI Responses - use base64]"
            }),
        },

        // OpenAI Responses doesn't support video/documents in chat input
        MediaPart::Video { .. } | MediaPart::Document { .. } => json!({
            "type": "input_text",
            "text": "[Video/Document not supported by this provider]"
        }),
    }
}

/// Convert a MultimodalMessage to provider-specific format
fn multimodal_to_provider_format(msg: &MultimodalMessage, provider: Provider) -> Value {
    let role = match msg.role {
        ChatRole::System => "system",
        ChatRole::User => "user",
        ChatRole::Assistant => "assistant",
        ChatRole::Tool => "tool",
    };

    let parts: Vec<Value> = msg
        .parts
        .iter()
        .map(|part| match provider {
            Provider::GoogleGenAI => media_part_to_google_format(part, None),
            Provider::Anthropic | Provider::Bedrock | Provider::GoogleAnthropic => {
                media_part_to_anthropic_format(part)
            }
            Provider::OpenAI
            | Provider::OpenRouter
            | Provider::OpenAIResponses
            | Provider::OpenRouterResponses => media_part_to_openai_format(part),
        })
        .collect();

    // Google uses "parts", others use "content" array
    match provider {
        Provider::GoogleGenAI => json!({
            "role": if role == "assistant" { "model" } else { role },
            "parts": parts
        }),
        _ => json!({
            "role": role,
            "content": parts
        }),
    }
}

/// Convert messages to OpenAI/OpenRouter Responses API input format.
///
/// Returns (instructions, input_items).
pub fn convert_messages_to_responses_input(
    messages: &[ConversationMessage],
    provider: Provider,
) -> Result<(Option<String>, Vec<Value>)> {
    let mut instructions: Vec<String> = Vec::new();
    let mut input_items: Vec<Value> = Vec::new();

    for msg in messages.iter() {
        match msg {
            ConversationMessage::Chat(chat_msg) => match chat_msg.role {
                ChatRole::System => {
                    instructions.push(chat_msg.content.clone());
                }
                ChatRole::User => {
                    input_items.push(json!({
                        "type": "message",
                        "role": "user",
                        "content": [{
                            "type": "input_text",
                            "text": chat_msg.content
                        }]
                    }));
                }
                ChatRole::Assistant => {
                    input_items.push(json!({
                        "type": "message",
                        "role": "assistant",
                        "id": format!("msg_{}", Uuid::new_v4()),
                        "status": "completed",
                        "content": [{
                            "type": "output_text",
                            "text": chat_msg.content,
                            "annotations": []
                        }]
                    }));
                }
                ChatRole::Tool => {
                    input_items.push(json!({
                        "type": "message",
                        "role": "tool",
                        "content": [{
                            "type": "input_text",
                            "text": chat_msg.content
                        }]
                    }));
                }
            },
            ConversationMessage::ToolCall(tool_call) => {
                let args_str = tool_call.raw_arguments.clone().unwrap_or_else(|| {
                    serde_json::to_string(&tool_call.args).unwrap_or_else(|_| "{}".to_string())
                });
                input_items.push(json!({
                    "type": "function_call",
                    "id": format!("fc_{}", tool_call.tool_use_id),
                    "call_id": tool_call.tool_use_id,
                    "name": tool_call.tool_name,
                    "arguments": args_str
                }));
            }
            ConversationMessage::ToolResult(tool_result) => {
                input_items.push(json!({
                    "type": "function_call_output",
                    "call_id": tool_result.tool_use_id,
                    "output": tool_result.content
                }));
            }
            ConversationMessage::Reasoning(reasoning_segment) => {
                input_items.push(json!({
                    "type": "reasoning",
                    "content": [{
                        "type": "output_text",
                        "text": reasoning_segment.content
                    }]
                }));
            }
            ConversationMessage::Multimodal(multimodal_msg) => {
                let role = match multimodal_msg.role {
                    ChatRole::System => "system",
                    ChatRole::User => "user",
                    ChatRole::Assistant => "assistant",
                    ChatRole::Tool => "tool",
                };

                let parts: Vec<Value> = multimodal_msg
                    .parts
                    .iter()
                    .map(|part| {
                        if matches!(
                            provider,
                            Provider::OpenAIResponses | Provider::OpenRouterResponses
                        ) {
                            match part {
                                MediaPart::Text { text } if role == "assistant" => json!({
                                    "type": "output_text",
                                    "text": text,
                                    "annotations": []
                                }),
                                _ => media_part_to_openai_responses_format(part),
                            }
                        } else {
                            media_part_to_openai_format(part)
                        }
                    })
                    .collect();

                let mut item = json!({
                    "type": "message",
                    "role": role,
                    "content": parts
                });

                if role == "assistant" {
                    item["id"] = json!(format!("msg_{}", Uuid::new_v4()));
                    item["status"] = json!("completed");
                }

                input_items.push(item);
            }
        }
    }

    let instructions = if instructions.is_empty() {
        None
    } else {
        Some(instructions.join("\n\n"))
    };

    Ok((instructions, input_items))
}

/// Convert messages to provider-specific format with coalescing
///
/// Provider-aware behavior:
/// - Anthropic/Bedrock/GoogleAnthropic: Coalesce consecutive ToolResults into a single user turn
///   with a content array of tool_result blocks. If the immediate next user ChatMessage exists,
///   append it as a trailing {"type":"text","text":"..."} block in the same message.
///
/// - Google GenAI: Coalesce consecutive ToolResults into a single user turn where 'content' is a list
///   of {"functionResponse": {...}} dicts. If the immediate next user ChatMessage exists, append
///   {"text": "..."} as a trailing entry.
///
/// - OpenAI/OpenRouter: Map each ToolResult to a proper tool-role message:
///   {"role":"tool","tool_call_id": tool_use_id, "content": result}
///   Keep subsequent user messages separate (no coalescing).
pub fn convert_messages_to_provider_format(
    messages: &[ConversationMessage],
    provider: Provider,
) -> Result<Vec<Value>> {
    let mut converted_messages: Vec<Value> = Vec::new();
    let mut pending_anthropic_blocks: Vec<Value> = Vec::new();
    let mut pending_google_parts: Vec<Value> = Vec::new();

    let flush_pending = |converted: &mut Vec<Value>,
                         anthropic_blocks: &mut Vec<Value>,
                         google_parts: &mut Vec<Value>| {
        match provider {
            Provider::Anthropic | Provider::Bedrock | Provider::GoogleAnthropic => {
                if !anthropic_blocks.is_empty() {
                    converted.push(json!({
                        "role": "user",
                        "content": anthropic_blocks.clone()
                    }));
                    anthropic_blocks.clear();
                }
            }
            Provider::GoogleGenAI => {
                if !google_parts.is_empty() {
                    converted.push(json!({
                        "role": "user",
                        "content": google_parts.clone()
                    }));
                    google_parts.clear();
                }
            }
            _ => {}
        }
    };

    for msg in messages.iter() {
        match msg {
            ConversationMessage::Chat(chat_msg) => {
                // Check if this is a user message that should be merged with pending tool results
                if chat_msg.role == ChatRole::User
                    && matches!(
                        provider,
                        Provider::Anthropic
                            | Provider::Bedrock
                            | Provider::GoogleAnthropic
                            | Provider::GoogleGenAI
                    )
                {
                    // Merge with pending tool results
                    if matches!(
                        provider,
                        Provider::Anthropic | Provider::Bedrock | Provider::GoogleAnthropic
                    ) && !pending_anthropic_blocks.is_empty()
                    {
                        // Only add text block if content is non-empty
                        // (Anthropic rejects "text content blocks must be non-empty")
                        if !chat_msg.content.is_empty() {
                            pending_anthropic_blocks.push(json!({
                                "type": "text",
                                "text": chat_msg.content
                            }));
                        }
                        flush_pending(
                            &mut converted_messages,
                            &mut pending_anthropic_blocks,
                            &mut pending_google_parts,
                        );
                        continue;
                    } else if provider == Provider::GoogleGenAI && !pending_google_parts.is_empty()
                    {
                        // Only add text part if content is non-empty
                        if !chat_msg.content.is_empty() {
                            pending_google_parts.push(json!({
                                "text": chat_msg.content
                            }));
                        }
                        flush_pending(
                            &mut converted_messages,
                            &mut pending_anthropic_blocks,
                            &mut pending_google_parts,
                        );
                        continue;
                    }
                }

                // Flush pending before adding this message
                flush_pending(
                    &mut converted_messages,
                    &mut pending_anthropic_blocks,
                    &mut pending_google_parts,
                );

                // Add regular chat message
                let role = match chat_msg.role {
                    ChatRole::System => "system",
                    ChatRole::User => "user",
                    ChatRole::Assistant => "assistant",
                    ChatRole::Tool => "tool",
                };

                converted_messages.push(json!({
                    "role": role,
                    "content": chat_msg.content
                }));
            }

            ConversationMessage::ToolCall(tool_call) => {
                // Flush pending before adding tool call
                flush_pending(
                    &mut converted_messages,
                    &mut pending_anthropic_blocks,
                    &mut pending_google_parts,
                );

                // Convert tool call to provider-specific assistant message format
                converted_messages.push(tool_call.to_provider_assistant_message(provider));
            }

            ConversationMessage::ToolResult(tool_result) => {
                match provider {
                    Provider::OpenAI
                    | Provider::OpenRouter
                    | Provider::OpenAIResponses
                    | Provider::OpenRouterResponses => {
                        // OpenAI: Each ToolResult becomes a separate tool message
                        flush_pending(
                            &mut converted_messages,
                            &mut pending_anthropic_blocks,
                            &mut pending_google_parts,
                        );
                        converted_messages.push(tool_result.to_provider_format(provider));
                    }
                    Provider::Anthropic | Provider::Bedrock | Provider::GoogleAnthropic => {
                        // Anthropic: Accumulate tool results for coalescing
                        pending_anthropic_blocks.push(tool_result.to_provider_format(provider));
                    }
                    Provider::GoogleGenAI => {
                        // Google GenAI: Accumulate function responses
                        pending_google_parts.push(tool_result.to_provider_format(provider));
                    }
                }
            }

            ConversationMessage::Reasoning(reasoning_segment) => {
                // Flush pending before adding reasoning
                flush_pending(
                    &mut converted_messages,
                    &mut pending_anthropic_blocks,
                    &mut pending_google_parts,
                );

                // Add reasoning segment as-is (providers handle differently)
                converted_messages.push(reasoning_segment.to_provider_format(provider));
            }

            ConversationMessage::Multimodal(multimodal_msg) => {
                // Flush pending before adding multimodal message
                flush_pending(
                    &mut converted_messages,
                    &mut pending_anthropic_blocks,
                    &mut pending_google_parts,
                );

                // Convert multimodal message to provider format
                converted_messages.push(multimodal_to_provider_format(multimodal_msg, provider));
            }
        }
    }

    // Flush any trailing pending tool results
    flush_pending(
        &mut converted_messages,
        &mut pending_anthropic_blocks,
        &mut pending_google_parts,
    );

    Ok(converted_messages)
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn test_openai_no_coalescing() {
        // OpenAI should NOT coalesce tool results
        let messages = vec![
            ConversationMessage::Chat(ChatMessage::user("Use the weather tool")),
            ConversationMessage::ToolResult(ToolResult::success("toolu_1", "Sunny, 72°F")),
            ConversationMessage::ToolResult(ToolResult::success("toolu_2", "Rainy, 55°F")),
            ConversationMessage::Chat(ChatMessage::user("Thanks!")),
        ];

        let result = convert_messages_to_provider_format(&messages, Provider::OpenAI).unwrap();

        // Should be 4 separate messages
        assert_eq!(result.len(), 4);

        // First message: user
        assert_eq!(result[0]["role"], "user");
        assert_eq!(result[0]["content"], "Use the weather tool");

        // Second message: tool result
        assert_eq!(result[1]["role"], "tool");
        assert_eq!(result[1]["tool_call_id"], "toolu_1");

        // Third message: tool result
        assert_eq!(result[2]["role"], "tool");
        assert_eq!(result[2]["tool_call_id"], "toolu_2");

        // Fourth message: user
        assert_eq!(result[3]["role"], "user");
        assert_eq!(result[3]["content"], "Thanks!");
    }

    #[test]
    fn test_anthropic_coalesces_tool_results() {
        // Anthropic SHOULD coalesce consecutive tool results
        let messages = vec![
            ConversationMessage::Chat(ChatMessage::user("Use the weather tool")),
            ConversationMessage::ToolResult(ToolResult::success("toolu_1", "Sunny, 72°F")),
            ConversationMessage::ToolResult(ToolResult::success("toolu_2", "Rainy, 55°F")),
        ];

        let result = convert_messages_to_provider_format(&messages, Provider::Anthropic).unwrap();

        // Should be 2 messages: original user message + coalesced tool results
        assert_eq!(result.len(), 2);

        // First message: user
        assert_eq!(result[0]["role"], "user");

        // Second message: coalesced tool results
        assert_eq!(result[1]["role"], "user");
        let content = result[1]["content"].as_array().unwrap();
        assert_eq!(content.len(), 2);
        assert_eq!(content[0]["type"], "tool_result");
        assert_eq!(content[0]["tool_use_id"], "toolu_1");
        assert_eq!(content[1]["type"], "tool_result");
        assert_eq!(content[1]["tool_use_id"], "toolu_2");
    }

    #[test]
    fn test_anthropic_merges_trailing_user_message() {
        // Anthropic SHOULD merge trailing user message with tool results
        let messages = vec![
            ConversationMessage::Chat(ChatMessage::user("Use the weather tool")),
            ConversationMessage::ToolResult(ToolResult::success("toolu_1", "Sunny, 72°F")),
            ConversationMessage::Chat(ChatMessage::user("Thanks!")),
        ];

        let result = convert_messages_to_provider_format(&messages, Provider::Anthropic).unwrap();

        // Should be 2 messages: original user + coalesced (tool result + trailing user text)
        assert_eq!(result.len(), 2);

        // Second message should have both tool result AND text
        let content = result[1]["content"].as_array().unwrap();
        assert_eq!(content.len(), 2);
        assert_eq!(content[0]["type"], "tool_result");
        assert_eq!(content[1]["type"], "text");
        assert_eq!(content[1]["text"], "Thanks!");
    }

    #[test]
    fn test_google_genai_coalescing() {
        // Google GenAI should coalesce tool results as functionResponse parts
        let messages = vec![
            ConversationMessage::Chat(ChatMessage::user("Use the weather tool")),
            ConversationMessage::ToolResult(ToolResult::success("toolu_1", "Sunny, 72°F")),
            ConversationMessage::ToolResult(ToolResult::success("toolu_2", "Rainy, 55°F")),
        ];

        let result = convert_messages_to_provider_format(&messages, Provider::GoogleGenAI).unwrap();

        // Should be 2 messages
        assert_eq!(result.len(), 2);

        // Second message: coalesced function responses
        assert_eq!(result[1]["role"], "user");
        let content = result[1]["content"].as_array().unwrap();
        assert_eq!(content.len(), 2);
        assert!(content[0].get("functionResponse").is_some());
        assert!(content[1].get("functionResponse").is_some());
    }

    #[test]
    fn test_responses_input_conversion() {
        let messages = vec![
            ConversationMessage::Chat(ChatMessage::system("You are helpful")),
            ConversationMessage::Chat(ChatMessage::user("Hello")),
            ConversationMessage::ToolResult(ToolResult::success("call_1", "Result")),
        ];

        let (instructions, input) =
            convert_messages_to_responses_input(&messages, Provider::OpenAIResponses).unwrap();

        assert_eq!(instructions.unwrap(), "You are helpful");
        assert_eq!(input.len(), 2);
        assert_eq!(input[0]["role"], "user");
        assert_eq!(input[0]["content"][0]["type"], "input_text");
        assert_eq!(input[1]["type"], "function_call_output");
        assert_eq!(input[1]["call_id"], "call_1");
    }

    #[test]
    fn test_google_genai_merges_trailing_user_message() {
        // Google GenAI should merge trailing user message as text part
        let messages = vec![
            ConversationMessage::ToolResult(ToolResult::success("toolu_1", "Sunny, 72°F")),
            ConversationMessage::Chat(ChatMessage::user("Thanks!")),
        ];

        let result = convert_messages_to_provider_format(&messages, Provider::GoogleGenAI).unwrap();

        // Should be 1 message with both functionResponse and text
        assert_eq!(result.len(), 1);

        let content = result[0]["content"].as_array().unwrap();
        assert_eq!(content.len(), 2);
        assert!(content[0].get("functionResponse").is_some());
        assert_eq!(content[1]["text"], "Thanks!");
    }

    #[test]
    fn test_system_message_preserved() {
        let messages = vec![
            ConversationMessage::Chat(ChatMessage::system("You are helpful")),
            ConversationMessage::Chat(ChatMessage::user("Hello")),
        ];

        let result = convert_messages_to_provider_format(&messages, Provider::OpenAI).unwrap();

        assert_eq!(result.len(), 2);
        assert_eq!(result[0]["role"], "system");
        assert_eq!(result[0]["content"], "You are helpful");
    }

    #[test]
    fn test_reasoning_segments_not_coalesced() {
        let messages = vec![
            ConversationMessage::Chat(ChatMessage::user("Think about this")),
            ConversationMessage::Reasoning(ReasoningSegment::with_index("Hmm...", 0)),
            ConversationMessage::Chat(ChatMessage::assistant("I understand")),
        ];

        let result = convert_messages_to_provider_format(&messages, Provider::Anthropic).unwrap();

        // Reasoning segments should be separate messages
        assert_eq!(result.len(), 3);
        assert_eq!(result[1]["type"], "thinking");
    }
}