//! 跨 Provider 类型转换 —— `Message` ↔ OpenAI `OpenaiChatMessage`。
//!
//! Phase 1 引入：避免转换逻辑在 `LlmCycle`、各 Provider 中重复。
//! 这些函数期望作为**纯函数**被调用 —— 无内部状态，方便跨 Provider 复用。
//!
//! 转换范围：仅处理 `OpenaiChatMessage` ↔ `Message`、`ContentField` ↔ `Vec<ContentBlock>`。
//! 流式 chunk 转换见各 Provider 内部（OpenAI Chat / Anthropic）。

use serde_json::Value;

use crate::llm::types::message::{ContentBlock, Message};
use crate::llm::types::openai_message::{
    ContentField, OpenaiChatMessage, OpenaiContentPart,
};
use crate::llm::types::OpenaiToolCall;

/// `OpenaiChatMessage` → IR `Message`。
///
/// 转换规则：
/// - `Developer` / `System` → `Message::System`
/// - `User` → `Message::User`（含图片/音频等多模态 part → `ContentBlock`）
/// - `Assistant` → `Message::Assistant`（`tool_calls` 转为 `ContentBlock::ToolUse`）
/// - `Tool` → `Message::ToolResult`（`is_error` 暂为 `false`，OpenAI 不携带此标记）
/// - `Function`（已废弃）→ `Message::ToolResult`（`name` 作为 `tool_call_id` 兜底）
pub fn from_openai(msg: &OpenaiChatMessage) -> Message {
    match msg {
        OpenaiChatMessage::Developer { content, .. } | OpenaiChatMessage::System { content, .. } => {
            Message::System {
                content: content_to_blocks(content),
            }
        }
        OpenaiChatMessage::User { content, .. } => Message::User {
            content: content_to_blocks(content),
        },
        OpenaiChatMessage::Assistant {
            content,
            tool_calls,
            ..
        } => {
            let mut blocks = content_to_blocks(content);
            if let Some(calls) = tool_calls {
                for call in calls {
                    let OpenaiToolCall::Function { id, function } = call;
                    let input: Value =
                        serde_json::from_str(&function.arguments).unwrap_or(Value::Null);
                    blocks.push(ContentBlock::ToolUse {
                        id: id.clone(),
                        name: function.name.clone(),
                        input,
                    });
                }
            }
            Message::Assistant { content: blocks }
        }
        OpenaiChatMessage::Tool {
            content,
            tool_call_id,
        } => Message::ToolResult {
            tool_call_id: tool_call_id.clone(),
            content: content_to_blocks(content),
            is_error: false,
        },
        // ponytail: `function` 是 OpenAI 旧版 `function_call` API 残留变体；
        // 当前主流为 `tool_calls`，此处仅保留兼容路径。
        OpenaiChatMessage::Function { content, name } => Message::ToolResult {
            tool_call_id: name.clone(),
            content: content_to_blocks(content),
            is_error: false,
        },
    }
}

/// IR `Message` → `OpenaiChatMessage`。
///
/// ponytail 简化：当前 `Assistant.content` 仅序列化 Text → `content: String`，
/// `ToolUse` 拆出到 `tool_calls` 字段；thinking / image / audio / file / extension
/// 视为非 OpenAI 原生，**回传时丢弃**。Phase 2 切换为 `Vec<Message>` 后该丢弃
/// 自然消失（不再需要回传旧 wire 格式）。
pub fn to_openai(msg: &Message) -> OpenaiChatMessage {
    match msg {
        Message::System { content } => OpenaiChatMessage::System {
            content: blocks_to_content(content),
            name: None,
        },
        Message::User { content } => OpenaiChatMessage::User {
            content: blocks_to_content(content),
            name: None,
        },
        Message::UserImage { data, mime_type, detail } => {
            // ponytail: 构造为单 image part 的 User 消息（OpenAI 多模态格式）。
            let mime = mime_type.clone();
            let is_url = data.starts_with("http://") || data.starts_with("https://");
            let image_url = if is_url {
                crate::llm::types::openai_message::ImageURL {
                    url: data.clone(),
                    detail: Some(*detail),
                }
            } else {
                crate::llm::types::openai_message::ImageURL {
                    url: format!("data:{mime};base64,{data}"),
                    detail: Some(*detail),
                }
            };
            OpenaiChatMessage::User {
                content: ContentField::Array(vec![OpenaiContentPart::Image {
                    image_url,
                    detail: Some(*detail),
                }]),
                name: None,
            }
        }
        Message::Assistant { content } => {
            let mut text_blocks: Vec<String> = Vec::new();
            let mut tool_call_blocks: Vec<OpenaiToolCall> = Vec::new();
            for block in content {
                match block {
                    ContentBlock::Text { text } => text_blocks.push(text.clone()),
                    ContentBlock::ToolUse { id, name, input } => {
                        tool_call_blocks.push(OpenaiToolCall::Function {
                            id: id.clone(),
                            function: crate::llm::types::tool::FunctionCall {
                                name: name.clone(),
                                arguments: serde_json::to_string(input)
                                    .unwrap_or_else(|_| "null".to_string()),
                            },
                        });
                    }
                    // ponytail: thinking/refusal/image/audio/file/extension 在回传时被丢弃。
                    // Phase 2 切换后此函数整体移除，自然修复。
                    _ => {}
                }
            }
            let text: String = text_blocks.into_iter().collect();
            OpenaiChatMessage::Assistant {
                content: if text.is_empty() {
                    ContentField::Array(vec![])
                } else {
                    ContentField::String(text)
                },
                refusal: None,
                name: None,
                tool_calls: if tool_call_blocks.is_empty() {
                    None
                } else {
                    Some(tool_call_blocks)
                },
            }
        }
        Message::ToolResult {
            tool_call_id,
            content,
            is_error: _,
        } => OpenaiChatMessage::Tool {
            content: blocks_to_content(content),
            tool_call_id: tool_call_id.clone(),
        },
    }
}

/// `ContentField` → `Vec<ContentBlock>`。
///
/// 仅产出 OpenAI 有 wire 对应的 `Text` / `Image` / `Audio` /
/// `Refusal`（合并为 `Text`）block；`File` 被截断。
pub fn content_to_blocks(field: &ContentField) -> Vec<ContentBlock> {
    match field {
        ContentField::String(s) => vec![ContentBlock::Text { text: s.clone() }],
        ContentField::Array(parts) => parts
            .iter()
            .filter_map(|p| match p {
                OpenaiContentPart::Text { text } => {
                    Some(ContentBlock::Text { text: text.clone() })
                }
                OpenaiContentPart::Refusal { refusal } => {
                    Some(ContentBlock::Text { text: refusal.clone() })
                }
                OpenaiContentPart::Image { image_url, .. } => {
                    // ponytail: 简化处理 —— URL 直接通过，data URI 拆出
                    // data:<mime>;base64,<b64> → ImageSource { data: b64, mime, is_url: false }。
                    let url = &image_url.url;
                    if let Some(rest) = url.strip_prefix("data:")
                        && let Some((mime, b64)) = rest.split_once(";base64,") {
                            return Some(ContentBlock::Image {
                                source: crate::llm::types::message::ImageSource {
                                    data: b64.to_string(),
                                    mime_type: mime.to_string(),
                                    is_url: false,
                                },
                            });
                        }
                    Some(ContentBlock::Image {
                        source: crate::llm::types::message::ImageSource {
                            data: url.clone(),
                            mime_type: "image/url".to_string(),
                            is_url: true,
                        },
                    })
                }
                OpenaiContentPart::InputAudio { input_audio } => Some(ContentBlock::Audio {
                    source: crate::llm::types::message::AudioSource {
                        data: input_audio.data.clone(),
                        format: input_audio.format,
                    },
                }),
                // File 暂不映射（OpenAI File API 与 IR 不对齐）
                OpenaiContentPart::File { .. } => None,
            })
            .collect(),
    }
}

/// `Vec<ContentBlock>` → `ContentField`。
///
/// 单文本块 → `ContentField::String`；多块或非文本主导 → `ContentField::Array`。
pub fn blocks_to_content(blocks: &[ContentBlock]) -> ContentField {
    if let [ContentBlock::Text { text }] = blocks {
        return ContentField::String(text.clone());
    }
    let parts: Vec<OpenaiContentPart> = blocks
        .iter()
        .filter_map(|b| match b {
            ContentBlock::Text { text } => Some(OpenaiContentPart::Text { text: text.clone() }),
            ContentBlock::Image { source } => Some(OpenaiContentPart::Image {
                image_url: if source.is_url {
                    crate::llm::types::openai_message::ImageURL {
                        url: source.data.clone(),
                        detail: None,
                    }
                } else {
                    crate::llm::types::openai_message::ImageURL {
                        url: format!("data:{};base64,{}", source.mime_type, source.data),
                        detail: None,
                    }
                },
                detail: None,
            }),
            ContentBlock::Audio { source } => Some(OpenaiContentPart::InputAudio {
                input_audio: crate::llm::types::openai_message::InputAudio {
                    data: source.data.clone(),
                    format: source.format,
                },
            }),
            // ponytail: 其他 block 类型在 OpenAI wire 上无对应，回传时被截断。
            _ => None,
        })
        .collect();
    if parts.is_empty() {
        ContentField::Array(vec![])
    } else {
        ContentField::Array(parts)
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::llm::types::shared::ImageDetail;
    use serde_json::json;

    #[test]
    fn from_openai_system_maps_to_message_system() {
        let m = OpenaiChatMessage::system_text("you are helpful");
        let ir = from_openai(&m);
        match ir {
            Message::System { content } => {
                assert_eq!(content.len(), 1);
                assert!(matches!(&content[0], ContentBlock::Text { text } if text == "you are helpful"));
            }
            _ => panic!("expected System variant"),
        }
    }

    #[test]
    fn from_openai_assistant_tool_call_to_tool_use_block() {
        let m = OpenaiChatMessage::Assistant {
            content: ContentField::String("ok".into()),
            refusal: None,
            name: None,
            tool_calls: Some(vec![OpenaiToolCall::Function {
                id: "call_1".into(),
                function: crate::llm::types::tool::FunctionCall {
                    name: "search".into(),
                    arguments: r#"{"q":"rust"}"#.into(),
                },
            }]),
        };
        let ir = from_openai(&m);
        match ir {
            Message::Assistant { content } => {
                assert_eq!(content.len(), 2);
                match &content[1] {
                    ContentBlock::ToolUse { id, name, input } => {
                        assert_eq!(id, "call_1");
                        assert_eq!(name, "search");
                        assert_eq!(input, &json!({"q": "rust"}));
                    }
                    _ => panic!("expected ToolUse"),
                }
            }
            _ => panic!("expected Assistant"),
        }
    }

    #[test]
    fn from_openai_tool_to_tool_result() {
        let m = OpenaiChatMessage::Tool {
            content: ContentField::String("ok".into()),
            tool_call_id: "call_1".into(),
        };
        let ir = from_openai(&m);
        match ir {
            Message::ToolResult {
                tool_call_id,
                content,
                is_error,
            } => {
                assert_eq!(tool_call_id, "call_1");
                assert!(!is_error);
                assert_eq!(content.len(), 1);
            }
            _ => panic!("expected ToolResult"),
        }
    }

    #[test]
    fn to_openai_assistant_text_singular_string_content() {
        let m = Message::Assistant {
            content: vec![ContentBlock::Text { text: "hi".into() }],
        };
        let wire = to_openai(&m);
        match wire {
            OpenaiChatMessage::Assistant {
                content,
                tool_calls,
                ..
            } => {
                assert!(matches!(content, ContentField::String(s) if s == "hi"));
                assert!(tool_calls.is_none());
            }
            _ => panic!("expected Assistant"),
        }
    }

    #[test]
    fn to_openai_assistant_with_tool_use_produces_tool_calls() {
        let m = Message::Assistant {
            content: vec![
                ContentBlock::Text { text: "ok".into() },
                ContentBlock::ToolUse {
                    id: "call_1".into(),
                    name: "search".into(),
                    input: json!({"q": "rust"}),
                },
            ],
        };
        let wire = to_openai(&m);
        match wire {
            OpenaiChatMessage::Assistant {
                content,
                tool_calls,
                ..
            } => {
                assert!(matches!(content, ContentField::String(_)));
                let calls = tool_calls.expect("tool_calls");
                assert_eq!(calls.len(), 1);
                let OpenaiToolCall::Function { id, function } = &calls[0];
                assert_eq!(id, "call_1");
                assert_eq!(function.name, "search");
                assert!(function.arguments.contains("rust"));
            }
            _ => panic!("expected Assistant"),
        }
    }

    #[test]
    fn to_openai_user_image_builds_data_uri() {
        let m = Message::UserImage {
            data: "BASE64DATA".into(),
            mime_type: "image/png".into(),
            detail: ImageDetail::High,
        };
        let wire = to_openai(&m);
        match wire {
            OpenaiChatMessage::User { content, .. } => match content {
                ContentField::Array(parts) => {
                    assert_eq!(parts.len(), 1);
                    match &parts[0] {
                        OpenaiContentPart::Image { image_url, .. } => {
                            assert_eq!(
                                image_url.url,
                                "data:image/png;base64,BASE64DATA"
                            );
                        }
                        _ => panic!("expected Image part"),
                    }
                }
                _ => panic!("expected Array content"),
            },
            _ => panic!("expected User"),
        }
    }

    #[test]
    fn blocks_to_content_singular_text_uses_string() {
        let blocks = vec![ContentBlock::Text { text: "hi".into() }];
        let f = blocks_to_content(&blocks);
        assert!(matches!(f, ContentField::String(s) if s == "hi"));
    }

    #[test]
    fn blocks_to_content_multiple_blocks_uses_array() {
        let blocks = vec![
            ContentBlock::Text { text: "a".into() },
            ContentBlock::Text { text: "b".into() },
        ];
        let f = blocks_to_content(&blocks);
        assert!(matches!(f, ContentField::Array(parts) if parts.len() == 2));
    }

    #[test]
    fn content_to_blocks_refusal_merges_to_text() {
        let field = ContentField::Array(vec![OpenaiContentPart::Refusal {
            refusal: "policy violation".into(),
        }]);
        let blocks = content_to_blocks(&field);
        assert_eq!(blocks.len(), 1);
        assert!(matches!(&blocks[0], ContentBlock::Text { text } if text == "policy violation"));
    }

    #[test]
    fn roundtrip_image_via_data_uri() {
        let field = ContentField::Array(vec![OpenaiContentPart::Image {
            image_url: crate::llm::types::openai_message::ImageURL {
                url: "data:image/png;base64,AAA".into(),
                detail: Some(ImageDetail::Auto),
            },
            detail: None,
        }]);
        let blocks = content_to_blocks(&field);
        assert_eq!(blocks.len(), 1);
        match &blocks[0] {
            ContentBlock::Image { source } => {
                assert_eq!(source.data, "AAA");
                assert_eq!(source.mime_type, "image/png");
                assert!(!source.is_url);
            }
            _ => panic!("expected Image"),
        }
    }
}