//! Anthropic Messages API Provider —— Phase 1 引入。
//!
//! Anthropic SSE 事件序列：`message_start` → `content_block_start` → `content_block_delta`
//! → `content_block_stop` → `message_delta` → `message_stop`。与 OpenAI 不同，
//! Anthropic 提供显式 block 边界事件，状态机相对简单。

use std::pin::Pin;
use std::task::{Context, Poll};
use std::time::Duration;

use async_trait::async_trait;
use bytes::Bytes;
use futures_core::Stream;
use futures_util::StreamExt;
use reqwest::header::{HeaderMap, HeaderValue};
use reqwest::Client;
use serde::{Deserialize, Serialize};
use serde_json::{json, Value};
use tracing::{debug, error, info, warn};

use super::{LlmProvider, ProviderCapabilities, ProviderFeatures};
use crate::llm::error::LlmError;
use crate::llm::types::message::{ContentBlock, ContentBlockType, Message};
use crate::llm::types::request_v2::MessageRequest;
use crate::llm::types::response_v2::{
    MessageResponse, PartialMessageResponse, PartialUsage, StopReason, StreamEvent,
};
use crate::llm::types::usage::Usage;

/// Anthropic Provider 默认 `max_tokens` 兜底值。
///
/// Anthropic Messages API 要求 `max_tokens` 为必填字段，`MessageRequest.max_tokens`
/// 为 `Option<u32>`。未设置时使用此默认值。
const DEFAULT_MAX_TOKENS: u32 = 4096;

pub struct AnthropicProvider {
    http_client: Client,
    base_url: String,
    #[allow(dead_code)]
    api_key: String,
    model: String,
}

impl AnthropicProvider {
    pub fn new(base_url: String, api_key: String, model: String) -> Self {
        let key_header = HeaderValue::from_str(&api_key)
            .expect("Anthropic API key 包含无效的 HTTP 头部字符");
        let version_header = HeaderValue::from_static("2023-06-01");

        let http_client = Client::builder()
            .timeout(Duration::from_secs(120))
            .default_headers({
                let mut headers = HeaderMap::new();
                headers.insert("x-api-key", key_header);
                headers.insert("anthropic-version", version_header);
                headers
            })
            .build()
            .expect("创建 HTTP 客户端失败");

        Self {
            http_client,
            base_url: if base_url.is_empty() {
                "https://api.anthropic.com".to_string()
            } else {
                base_url
            },
            api_key,
            model,
        }
    }

    pub fn with_client(mut self, client: Client) -> Self {
        self.http_client = client;
        self
    }

    fn resolve_max_tokens(&self, request: &MessageRequest) -> u32 {
        request.max_tokens.unwrap_or(DEFAULT_MAX_TOKENS)
    }

    /// `MessageRequest` → Anthropic Messages API 请求体。
    fn build_request_body(
        &self,
        request: MessageRequest,
    ) -> Result<AnthropicRequestBody, LlmError> {
        let mut system_prompts: Vec<String> = Vec::new();
        let mut api_messages: Vec<AnthropicMessage> = Vec::new();

        for msg in request.messages.iter() {
            match msg {
                Message::System { content } => {
                    // 提取所有 Text block 拼为单个 system prompt
                    let text: String = content
                        .iter()
                        .filter_map(|b| match b {
                            ContentBlock::Text { text } => Some(text.as_str()),
                            _ => None,
                        })
                        .collect::<Vec<&str>>()
                        .join("\n");
                    system_prompts.push(text);
                }
                Message::User { content } => {
                    api_messages.push(AnthropicMessage::user(content));
                }
                Message::UserImage { data, mime_type, detail } => {
                    // Anthropic image format: {type: "image", source: {type: "base64", media_type, data}}
                    let source = if data.starts_with("http://") || data.starts_with("https://") {
                        AnthropicImageSource::Url {
                            url: data.clone(),
                        }
                    } else {
                        AnthropicImageSource::Base64 {
                            media_type: mime_type.clone(),
                            data: data.clone(),
                        }
                    };
                    let _ = detail; // 当前忽略 ImageDetail，Anthropic 不支持
                    api_messages.push(AnthropicMessage::User {
                        content: vec![AnthropicContentPart::Image { source }],
                    });
                }
                Message::Assistant { content } => {
                    api_messages.push(AnthropicMessage::assistant(content));
                }
                Message::ToolResult {
                    tool_call_id,
                    content,
                    is_error,
                } => {
                    api_messages.push(AnthropicMessage::User {
                        content: vec![AnthropicContentPart::ToolResult {
                            tool_use_id: tool_call_id.clone(),
                            content: serialize_tool_result_content(content),
                            is_error: *is_error,
                        }],
                    });
                }
            }
        }

        let max_tokens = self.resolve_max_tokens(&request);

        let tools = if request.tools.is_empty() {
            None
        } else {
            Some(
                request
                    .tools
                    .into_iter()
                    .map(|t| AnthropicToolDefinition {
                        name: t.name.clone(),
                        description: t.description.clone().unwrap_or_default(),
                        input_schema: t.parameters.clone(),
                    })
                    .collect(),
            )
        };

        let thinking = request.thinking.clone().map(|tc| AnthropicThinking {
            ty: "enabled",
            budget_tokens: tc.budget_tokens,
        });

        Ok(AnthropicRequestBody {
            model: if request.model.is_empty() {
                self.model.clone()
            } else {
                request.model
            },
            max_tokens,
            system: if system_prompts.is_empty() {
                None
            } else {
                Some(system_prompts.join("\n"))
            },
            messages: api_messages,
            tools,
            thinking,
            stream: if request.stream { Some(true) } else { None },
        })
    }

    async fn chat_blocking(&self, request: MessageRequest) -> Result<MessageResponse, LlmError> {
        let body = self.build_request_body(request)?;
        let url = format!("{}/v1/messages", self.base_url.trim_end_matches('/'));

        info!(model = %body.model, "Anthropic: 发送非流式请求");

        let response = self
            .http_client
            .post(&url)
            .json(&body)
            .send()
            .await
            .map_err(Self::map_reqwest_error)?;

        let status = response.status();
        if !status.is_success() {
            return Err(Self::handle_error_response(response).await);
        }

        let body_text = response.text().await.unwrap_or_default();
        debug!(body = %body_text, "Anthropic: 收到响应体");

        let resp: AnthropicResponseBody = serde_json::from_str(&body_text).map_err(|e| {
            error!(error = %e, "Anthropic 响应解析失败");
            LlmError::Other(format!("响应解析失败: {e}"))
        })?;

        Ok(Self::convert_response(resp))
    }

    async fn chat_stream_inner(
        &self,
        request: MessageRequest,
    ) -> Result<Pin<Box<dyn Stream<Item = Result<StreamEvent, LlmError>> + Send>>, LlmError>
    {
        let mut body = self.build_request_body(request)?;
        body.stream = Some(true);

        let url = format!("{}/v1/messages", self.base_url.trim_end_matches('/'));

        info!(model = %body.model, "Anthropic: 发送流式请求");

        let response = self
            .http_client
            .post(&url)
            .json(&body)
            .send()
            .await
            .map_err(Self::map_reqwest_error)?;

        let status = response.status();
        if !status.is_success() {
            return Err(Self::handle_error_response(response).await);
        }

        let byte_stream = response.bytes_stream().map(|r| {
            r.map_err(|e| LlmError::Other(format!("流式读取失败: {e}")))
        });

        let byte_stream: Pin<Box<dyn Stream<Item = Result<Bytes, LlmError>> + Send>> =
            Box::pin(byte_stream);

        Ok(Box::pin(AnthropicSseStream::new(byte_stream)))
    }

    fn map_reqwest_error(e: reqwest::Error) -> LlmError {
        if e.is_timeout() {
            LlmError::Timeout {
                duration: Duration::from_secs(120),
            }
        } else if e.is_connect() {
            LlmError::Other(format!("连接失败: {e}"))
        } else {
            LlmError::Other(format!("请求失败: {e}"))
        }
    }

    /// Anthropic 错误映射：529（overloaded）→ RateLimit；401/403 → Authentication。
    async fn handle_error_response(response: reqwest::Response) -> LlmError {
        let status = response.status().as_u16();

        // ponytail: 尝试解析 Anthropic 风格 error body（`{error: {type, message}}`）
        // 但即使解析失败也用 HTTP status + 原始 body 兜底。
        let retry_after = response
            .headers()
            .get("retry-after")
            .and_then(|v| v.to_str().ok())
            .and_then(|v| v.parse::<u64>().ok())
            .map(Duration::from_secs);

        let body = response.text().await.unwrap_or_default();

        match status {
            401 | 403 => LlmError::Authentication(body),
            429 => LlmError::RateLimit { retry_after },
            529 => LlmError::RateLimit { retry_after: None },
            _ => LlmError::Request { status, body },
        }
    }

    /// Anthropic 非流式响应 → `MessageResponse`。
    fn convert_response(resp: AnthropicResponseBody) -> MessageResponse {
        let mut blocks: Vec<ContentBlock> = Vec::new();
        for part in resp.content {
            match part {
                AnthropicContentBlockResp::Text { text } => {
                    blocks.push(ContentBlock::Text { text });
                }
                AnthropicContentBlockResp::ToolUse { id, name, input } => {
                    blocks.push(ContentBlock::ToolUse {
                        id,
                        name,
                        input,
                    });
                }
                AnthropicContentBlockResp::Thinking { thinking, signature } => {
                    blocks.push(ContentBlock::Thinking {
                        text: thinking,
                        signature,
                    });
                }
            }
        }

        let stop_reason = match resp.stop_reason.as_deref() {
            Some("end_turn") => StopReason::Stop,
            Some("max_tokens") => StopReason::MaxTokens,
            Some("tool_use") => StopReason::ToolUse,
            Some("stop_sequence") => StopReason::StopSequence,
            _ => StopReason::Stop,
        };

        let usage = Usage::from_input_output(resp.usage.input_tokens, resp.usage.output_tokens);

        MessageResponse {
            id: resp.id,
            model: resp.model,
            message: Message::Assistant { content: blocks },
            usage,
            stop_reason,
            extra: Default::default(),
        }
    }
}

#[async_trait]
impl LlmProvider for AnthropicProvider {
    async fn chat(&self, request: MessageRequest) -> Result<MessageResponse, LlmError> {
        self.chat_blocking(request).await
    }

    async fn chat_stream(
        &self,
        request: MessageRequest,
    ) -> Result<Pin<Box<dyn Stream<Item = Result<StreamEvent, LlmError>> + Send>>, LlmError>
    {
        self.chat_stream_inner(request).await
    }

    fn capabilities(&self) -> ProviderCapabilities {
        ProviderCapabilities {
            provider_name: "anthropic",
            supported_models: Some(vec![
                "claude-sonnet-4-20250514".into(),
                "claude-3-5-sonnet-20241022".into(),
            ]),
            features: ProviderFeatures {
                streaming: true,
                thinking: true,
                vision: true,
                audio_input: false,
                tool_use: true,
                parallel_tool_calls: false,
                system_prompt_in_messages: false,
                max_context_window: 200_000,
            },
        }
    }
}

// =============================================================================
// Anthropic 协议类型（私有）
// =============================================================================

#[derive(Debug, Serialize)]
struct AnthropicRequestBody {
    model: String,
    max_tokens: u32,
    #[serde(skip_serializing_if = "Option::is_none")]
    system: Option<String>,
    messages: Vec<AnthropicMessage>,
    #[serde(skip_serializing_if = "Option::is_none")]
    tools: Option<Vec<AnthropicToolDefinition>>,
    #[serde(skip_serializing_if = "Option::is_none")]
    thinking: Option<AnthropicThinking>,
    #[serde(skip_serializing_if = "Option::is_none")]
    stream: Option<bool>,
}

#[derive(Debug, Serialize)]
struct AnthropicThinking {
    ty: &'static str, // "enabled"
    budget_tokens: u32,
}

#[derive(Debug, Serialize)]
struct AnthropicToolDefinition {
    name: String,
    description: String,
    input_schema: Value,
}

#[derive(Debug, Serialize)]
#[serde(tag = "role", rename_all = "lowercase")]
enum AnthropicMessage {
    User { content: Vec<AnthropicContentPart> },
    Assistant { content: Vec<AnthropicContentPart> },
}

impl AnthropicMessage {
    fn user(content: &[ContentBlock]) -> Self {
        AnthropicMessage::User {
            content: content_to_parts(content),
        }
    }

    fn assistant(content: &[ContentBlock]) -> Self {
        AnthropicMessage::Assistant {
            content: content_to_parts(content),
        }
    }
}

#[derive(Debug, Serialize)]
#[serde(tag = "type", rename_all = "snake_case")]
enum AnthropicContentPart {
    Text { text: String },
    Image {
        source: AnthropicImageSource,
    },
    ToolUse {
        id: String,
        name: String,
        input: Value,
    },
    ToolResult {
        tool_use_id: String,
        content: Value,
        is_error: bool,
    },
}

#[derive(Debug, Serialize)]
#[serde(tag = "type", rename_all = "snake_case")]
enum AnthropicImageSource {
    Base64 {
        media_type: String,
        data: String,
    },
    Url {
        url: String,
    },
}

fn content_to_parts(blocks: &[ContentBlock]) -> Vec<AnthropicContentPart> {
    blocks
        .iter()
        .filter_map(|b| match b {
            ContentBlock::Text { text } => Some(AnthropicContentPart::Text { text: text.clone() }),
            ContentBlock::Image { source } => {
                let api_source = if source.is_url {
                    AnthropicImageSource::Url {
                        url: source.data.clone(),
                    }
                } else {
                    AnthropicImageSource::Base64 {
                        media_type: source.mime_type.clone(),
                        data: source.data.clone(),
                    }
                };
                Some(AnthropicContentPart::Image { source: api_source })
            }
            ContentBlock::ToolUse { id, name, input } => Some(AnthropicContentPart::ToolUse {
                id: id.clone(),
                name: name.clone(),
                input: input.clone(),
            }),
            ContentBlock::Thinking { text, signature: _ } => {
                // ponytail: 暂未映射 Thinking 到 Anthropic wire（Anthropic 自动产生）。
                // Phase 2 后通过专门的 thinking 支持扩展。
                if text.is_empty() {
                    None
                } else {
                    Some(AnthropicContentPart::Text { text: text.clone() })
                }
            }
            // ponytail: Audio / File / ToolResult / Extension 在 Anthropic 上
            // 由 ToolResult 单独通过 AnthropicMessage 路径处理，不走 content_to_parts。
            // 这里保持非穷举的兜底匹配。
            _ => None,
        })
        .collect()
}

fn serialize_tool_result_content(blocks: &[ContentBlock]) -> Value {
    // Anthropic tool_result.content 接受 string 或 array of content blocks。
    // 简化：单文本 → string；多块或非文本 → array。
    if let [ContentBlock::Text { text }] = blocks {
        return Value::String(text.clone());
    }
    let arr: Vec<Value> = blocks
        .iter()
        .filter_map(|b| match b {
            ContentBlock::Text { text } => Some(json!({"type": "text", "text": text})),
            _ => None,
        })
        .collect();
    Value::Array(arr)
}

#[derive(Debug, Deserialize)]
struct AnthropicResponseBody {
    id: String,
    #[allow(dead_code)]
    #[serde(rename = "type")]
    ty: String,
    model: String,
    content: Vec<AnthropicContentBlockResp>,
    stop_reason: Option<String>,
    usage: AnthropicUsage,
}

#[derive(Debug, Deserialize)]
struct AnthropicUsage {
    input_tokens: u32,
    output_tokens: u32,
}

#[derive(Debug, Deserialize)]
#[serde(tag = "type", rename_all = "snake_case")]
enum AnthropicContentBlockResp {
    Text { text: String },
    ToolUse { id: String, name: String, input: Value },
    Thinking { thinking: String, signature: Option<String> },
}

// =============================================================================
// SSE 流 → StreamEvent 状态机
// =============================================================================

/// Anthropic SSE 事件。
#[derive(Debug, Deserialize)]
#[serde(tag = "type", rename_all = "snake_case")]
enum AnthropicSseEvent {
    MessageStart {
        message: AnthropicMessageStart,
    },
    ContentBlockStart {
        index: u32,
        content_block: AnthropicContentBlockStart,
    },
    ContentBlockDelta {
        index: u32,
        delta: AnthropicDelta,
    },
    ContentBlockStop {
        index: u32,
    },
    MessageDelta {
        delta: AnthropicMessageDeltaInner,
        usage: Option<AnthropicMessageDeltaUsage>,
    },
    MessageStop,
    Ping,
    #[serde(other)]
    Unknown,
}

#[derive(Debug, Deserialize)]
struct AnthropicMessageStart {
    id: String,
    model: String,
}

#[derive(Debug, Deserialize)]
#[serde(tag = "type", rename_all = "snake_case")]
enum AnthropicContentBlockStart {
    Text { text: String },
    ToolUse { id: String, name: String },
    Thinking { thinking: String },
}

#[derive(Debug, Deserialize)]
#[serde(tag = "type", rename_all = "snake_case")]
enum AnthropicDelta {
    TextDelta { text: String },
    InputJson { partial_json: String },
    ThinkingDelta { thinking: String },
    SignatureDelta { signature: String },
}

#[derive(Debug, Deserialize)]
struct AnthropicMessageDeltaInner {
    stop_reason: Option<String>,
    #[serde(default)]
    #[allow(dead_code)]
    stop_sequence: Option<String>,
}

#[derive(Debug, Deserialize)]
struct AnthropicMessageDeltaUsage {
    output_tokens: u32,
    input_tokens: Option<u32>,
}

pub struct AnthropicSseStream {
    chunks: Pin<Box<dyn Stream<Item = Result<Bytes, LlmError>> + Send>>,
    buffer: String,
    partial: PartialMessageResponse,
    #[allow(dead_code)]
    next_block_index: u32,
    saw_terminal: bool,
}

impl AnthropicSseStream {
    fn new(chunks: Pin<Box<dyn Stream<Item = Result<Bytes, LlmError>> + Send>>) -> Self {
        Self {
            chunks,
            buffer: String::new(),
            partial: PartialMessageResponse::new(),
            next_block_index: 0,
            saw_terminal: false,
        }
    }

    fn next_event_line(&mut self) -> Option<String> {
        // Anthropic SSE 多行：event: ... / data: ... 之间有空行（清空字段）。
        // 简化：每次找出 `\n` 切分后找下一个 `data:` 行。
        while let Some(pos) = self.buffer.find('\n') {
            let line: String = self.buffer.drain(..=pos).collect::<String>();
            let trimmed = line.trim();
            if trimmed.is_empty() {
                continue;
            }
            if let Some(data) = trimmed.strip_prefix("data: ") {
                return Some(data.to_string());
            }
            // 跳 event: 行 / 空注释
        }
        None
    }

    fn handle_event_json(&mut self, data: &str) -> Vec<StreamEvent> {
        let event: AnthropicSseEvent = match serde_json::from_str(data) {
            Ok(e) => e,
            Err(err) => {
                warn!(error = %err, raw = %data, "Anthropic SSE event parse failed");
                return vec![StreamEvent::Error {
                    message: format!("SSE 解析失败: {err}"),
                }];
            }
        };

        let mut events = Vec::new();
        match event {
            AnthropicSseEvent::MessageStart { message } => {
                events.push(StreamEvent::MessageStart {
                    id: message.id.clone(),
                    model: message.model.clone(),
                });
                self.partial.id = Some(message.id);
                self.partial.model = Some(message.model);
            }
            AnthropicSseEvent::ContentBlockStart {
                index,
                content_block,
            } => {
                // 先把所有字段提前，避免 match 中 part-move
                let block_type = match &content_block {
                    AnthropicContentBlockStart::Text { .. } => ContentBlockType::Text,
                    AnthropicContentBlockStart::ToolUse { id, name } => {
                        ContentBlockType::ToolUse {
                            id: id.clone(),
                            name: name.clone(),
                        }
                    }
                    AnthropicContentBlockStart::Thinking { .. } => ContentBlockType::Thinking,
                };
                events.push(StreamEvent::ContentBlockStart {
                    index,
                    block_type,
                });
                let builder = match content_block {
                    AnthropicContentBlockStart::Text { text } => {
                        crate::llm::types::response_v2::ContentBlockBuilder::Text(text)
                    }
                    AnthropicContentBlockStart::ToolUse { id, name } => {
                        crate::llm::types::response_v2::ContentBlockBuilder::ToolUse {
                            id,
                            name,
                            arguments: String::new(),
                        }
                    }
                    AnthropicContentBlockStart::Thinking { thinking } => {
                        crate::llm::types::response_v2::ContentBlockBuilder::Thinking {
                            buffer: thinking,
                            signature: None,
                        }
                    }
                };
                self.partial.blocks.entry(index).or_insert(builder);
                self.partial.last_open_index = Some(index);
            }
            AnthropicSseEvent::ContentBlockDelta { index, delta } => match delta {
                AnthropicDelta::TextDelta { text } => {
                    events.push(StreamEvent::TextDelta { text });
                    // ponytail: builder 通过末尾 `partial.apply_to(&ev)` 自动更新，
                    // 不需要此处手动 push —— 之前写错导致双重拼接。
                    self.partial.last_open_index = Some(index);
                }
                AnthropicDelta::InputJson { partial_json } => {
                    events.push(StreamEvent::ToolCallArgumentsDelta {
                        index,
                        arguments: partial_json,
                    });
                }
                AnthropicDelta::ThinkingDelta { thinking } => {
                    events.push(StreamEvent::ThinkingDelta { text: thinking });
                }
                AnthropicDelta::SignatureDelta { signature } => {
                    self.partial.set_thinking_signature(signature);
                }
            },
            AnthropicSseEvent::ContentBlockStop { index } => {
                // 不区分 text/refusal 与 tool_use，统一用 ContentBlockEnd；
                // 消费方在 ContentBlockStart 已知类型。
                events.push(StreamEvent::ContentBlockEnd { index });
                self.partial.block_completion.insert(index);
                if self.partial.last_open_index == Some(index) {
                    self.partial.last_open_index = None;
                }
            }
            AnthropicSseEvent::MessageDelta { delta, usage } => {
                if let Some(reason) = delta.stop_reason.as_deref() {
                    self.partial.stop_reason = Some(match reason {
                        "end_turn" => StopReason::Stop,
                        "max_tokens" => StopReason::MaxTokens,
                        "tool_use" => StopReason::ToolUse,
                        "stop_sequence" => StopReason::StopSequence,
                        _ => StopReason::Other,
                    });
                }
                if let Some(u) = usage {
                    let partial_usage = PartialUsage {
                        prompt_tokens: u.input_tokens,
                        completion_tokens: Some(u.output_tokens),
                        total_tokens: None,
                        completion_tokens_details: None,
                        prompt_tokens_details: None,
                    };
                    events.push(StreamEvent::CostUpdate { usage: partial_usage });
                }
            }
            AnthropicSseEvent::MessageStop => {
                // 收尾：partial.finalize() → MessageComplete
                if self.saw_terminal {
                    return events;
                }
                self.saw_terminal = true;
                match self.partial.clone().finalize() {
                    Ok(full) => {
                        events.push(StreamEvent::MessageComplete { full_response: full });
                    }
                    Err(e) => {
                        events.push(StreamEvent::Error {
                            message: e.to_string(),
                        });
                    }
                }
            }
            AnthropicSseEvent::Ping | AnthropicSseEvent::Unknown => {
                // 忽略
            }
        }

        // 应用 side effects
        for ev in &events {
            self.partial.apply_to(ev);
        }
        events
    }
}

fn _unused_marker() {}

impl Stream for AnthropicSseStream {
    type Item = Result<StreamEvent, LlmError>;

    fn poll_next(
        mut self: Pin<&mut Self>,
        cx: &mut Context<'_>,
    ) -> Poll<Option<Self::Item>> {
        loop {
            if let Some(data) = self.next_event_line() {
                let mut events = self.handle_event_json(&data);
                if !events.is_empty() {
                    return Poll::Ready(Some(Ok(events.remove(0))));
                }
                continue;
            }

            match Pin::new(&mut self.chunks).poll_next(cx) {
                Poll::Ready(Some(Ok(bytes))) => {
                    if let Ok(s) = std::str::from_utf8(&bytes) {
                        self.buffer.push_str(s);
                    }
                }
                Poll::Ready(Some(Err(e))) => return Poll::Ready(Some(Err(e))),
                Poll::Ready(None) => {
                    // 流关闭：如未收到 message_stop，主动 finalize
                    if !self.saw_terminal {
                        self.saw_terminal = true;
                        match self.partial.clone().finalize() {
                            Ok(full) => {
                                return Poll::Ready(Some(Ok(StreamEvent::MessageComplete {
                                    full_response: full,
                                })));
                            }
                            Err(e) => {
                                return Poll::Ready(Some(Ok(StreamEvent::Error {
                                    message: e.to_string(),
                                })));
                            }
                        }
                    }
                    return Poll::Ready(None);
                }
                Poll::Pending => return Poll::Pending,
            }
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::llm::types::request_v2::MessageRequest;
    use serde_json::json;
    use wiremock::matchers::{method, path};
    use wiremock::{Mock, MockServer, ResponseTemplate};

    fn make_provider(base_url: String) -> AnthropicProvider {
        // 跳过默认 header 注入：测试用自定义 base_url 直接 mock
        AnthropicProvider::new(base_url, "sk-ant-test".into(), "claude-sonnet-4-20250514".into())
    }

    #[tokio::test]
    async fn anthropic_chat_basic_text_response() {
        let server = MockServer::start().await;
        Mock::given(method("POST"))
            .and(path("/v1/messages"))
            .respond_with(ResponseTemplate::new(200).set_body_json(json!({
                "id": "msg_01test",
                "type": "message",
                "model": "claude-sonnet-4-20250514",
                "content": [{"type": "text", "text": "Hello from Claude!"}],
                "stop_reason": "end_turn",
                "usage": {"input_tokens": 10, "output_tokens": 5}
            })))
            .mount(&server)
            .await;

        let provider = make_provider(server.uri());
        let response = provider
            .chat_blocking(MessageRequest {
                model: "claude-sonnet-4-20250514".into(),
                messages: vec![Message::user_text("Hi")],
                ..Default::default()
            })
            .await
            .unwrap();
        assert_eq!(response.text(), "Hello from Claude!");
        assert_eq!(response.stop_reason, StopReason::Stop);
        assert_eq!(response.usage.prompt_tokens, 10);
    }

    #[tokio::test]
    async fn anthropic_401_maps_to_authentication() {
        let server = MockServer::start().await;
        Mock::given(method("POST"))
            .and(path("/v1/messages"))
            .respond_with(ResponseTemplate::new(401).set_body_string("invalid api key"))
            .mount(&server)
            .await;

        let provider = make_provider(server.uri());
        let err = provider
            .chat_blocking(MessageRequest {
                model: "claude-sonnet-4-20250514".into(),
                messages: vec![Message::user_text("Hi")],
                ..Default::default()
            })
            .await
            .unwrap_err();
        assert!(matches!(err, LlmError::Authentication(_)));
    }

    #[tokio::test]
    async fn anthropic_529_overloaded_maps_to_rate_limit() {
        let server = MockServer::start().await;
        Mock::given(method("POST"))
            .and(path("/v1/messages"))
            .respond_with(ResponseTemplate::new(529).set_body_string("overloaded"))
            .mount(&server)
            .await;

        let provider = make_provider(server.uri());
        let err = provider
            .chat_blocking(MessageRequest {
                model: "claude-sonnet-4-20250514".into(),
                messages: vec![Message::user_text("Hi")],
                ..Default::default()
            })
            .await
            .unwrap_err();
        assert!(matches!(err, LlmError::RateLimit { .. }));
    }

    #[tokio::test]
    async fn anthropic_stream_emits_message_complete() {
        let server = MockServer::start().await;

        let sse = "event: message_start\ndata: {\"type\":\"message_start\",\"message\":{\"id\":\"msg_s1\",\"model\":\"claude-sonnet-4-20250514\"}}\n\n\
event: content_block_start\ndata: {\"type\":\"content_block_start\",\"index\":0,\"content_block\":{\"type\":\"text\",\"text\":\"\"}}\n\n\
event: content_block_delta\ndata: {\"type\":\"content_block_delta\",\"index\":0,\"delta\":{\"type\":\"text_delta\",\"text\":\"Hi\"}}\n\n\
event: content_block_delta\ndata: {\"type\":\"content_block_delta\",\"index\":0,\"delta\":{\"type\":\"text_delta\",\"text\":\" there\"}}\n\n\
event: content_block_stop\ndata: {\"type\":\"content_block_stop\",\"index\":0}\n\n\
event: message_delta\ndata: {\"type\":\"message_delta\",\"delta\":{\"stop_reason\":\"end_turn\"},\"usage\":{\"output_tokens\":3,\"input_tokens\":7}}\n\n\
event: message_stop\ndata: {\"type\":\"message_stop\"}\n\n";

        Mock::given(method("POST"))
            .and(path("/v1/messages"))
            .respond_with(
                ResponseTemplate::new(200)
                    .insert_header("content-type", "text/event-stream")
                    .set_body_string(sse),
            )
            .mount(&server)
            .await;

        let provider = make_provider(server.uri());
        let mut stream = provider
            .chat_stream_inner(MessageRequest {
                model: "claude-sonnet-4-20250514".into(),
                messages: vec![Message::user_text("Hello")],
                stream: true,
                ..Default::default()
            })
            .await
            .unwrap();

        use futures_util::StreamExt;
        let mut collected: Vec<StreamEvent> = Vec::new();
        while let Some(ev) = stream.next().await {
            collected.push(ev.unwrap());
        }

        let complete = collected
            .iter()
            .find_map(|e| match e {
                StreamEvent::MessageComplete { full_response } => Some(full_response.clone()),
                _ => None,
            })
            .expect("expected MessageComplete");
        assert_eq!(complete.text(), "Hi there");
        assert_eq!(complete.stop_reason, StopReason::Stop);
        assert_eq!(complete.usage.prompt_tokens, 7);

        // 应当看到 MessageStart + ContentBlockStart + 2 个 TextDelta + ContentBlockEnd + CostUpdate + MessageComplete
        let starts = collected
            .iter()
            .filter(|e| matches!(e, StreamEvent::MessageStart { .. }))
            .count();
        assert_eq!(starts, 1);
        let cost = collected.iter().find_map(|e| match e {
            StreamEvent::CostUpdate { usage } => Some(usage.clone()),
            _ => None,
        });
        assert_eq!(cost.and_then(|u| u.completion_tokens), Some(3));
    }

    #[test]
    fn anthropic_capabilities_reports_thinking_and_tool_use() {
        let caps = AnthropicProvider::new(
            "http://x".into(),
            "k".into(),
            "claude-sonnet-4-20250514".into(),
        )
        .capabilities();
        assert_eq!(caps.provider_name, "anthropic");
        assert!(caps.features.thinking);
        assert!(caps.features.tool_use);
        assert_eq!(caps.features.max_context_window, 200_000);
    }

    #[tokio::test]
    async fn anthropic_default_max_tokens_when_missing() {
        // 不通过 wire —— 仅测试 convert_request 默认 max_tokens
        let provider = make_provider("http://x".into());
        let req = MessageRequest {
            model: "claude-sonnet-4-20250514".into(),
            messages: vec![Message::user_text("Hi")],
            ..Default::default()
        };
        let body = provider.build_request_body(req).unwrap();
        assert_eq!(body.max_tokens, DEFAULT_MAX_TOKENS);
        assert_eq!(body.model, "claude-sonnet-4-20250514");
    }
}