use super::{request::*, response::*};
use anyhow::{bail, Result};
use eventsource_stream::Eventsource;
use futures::stream::StreamExt;
use reqwest::{
    header::{HeaderMap, HeaderValue, CACHE_CONTROL, CONTENT_TYPE},
    multipart, Method, Request,
};
use serde::Serialize;
use std::fmt::{Display, Formatter, Result as FmtResult};
use std::sync::Arc;
use std::time::Duration;

/// API 路径
#[derive(Debug)]
pub enum ApiPath {
    /// 发送对话消息, 创建会话消息。
    ChatMessages,
    /// 上传文件
    /// 上传文件（目前仅支持图片）并在发送消息时使用，可实现图文多模态理解。  
    /// 支持 png, jpg, jpeg, webp, gif 格式。  
    /// 上传的文件仅供当前终端用户使用。
    FilesUpload,
    /// 停止响应, 仅支持流式模式。
    ChatMessagesStop,
    /// 消息反馈（点赞, 消息终端用户反馈、点赞，方便应用开发者优化输出预期。
    MessagesFeedbacks,
    /// 获取下一轮建议问题列表
    MessagesSuggested,
    /// 获取会话历史消息, 滚动加载形式返回历史聊天记录，第一页返回最新 limit 条，即：倒序返回。
    Messages,
    /// 获取会话列表, 获取当前用户的会话列表，默认返回最近的 20 条。
    Conversations,
    /// 删除会话
    ConversationsDelete,
    /// 会话重命名, 对会话进行重命名，会话名称用于显示在支持多会话的客户端上。
    ConversationsRename,
    /// 语音转文字
    AudioToText,
    /// 文字转语音
    TextToAudio,
    /// 获取应用配置信息, 用于进入页面一开始，获取功能开关、输入参数名称、类型及默认值等使用。
    Parameters,
    /// 获取应用Meta信息, 用于获取工具icon
    Meta,
}

/// API 路径
impl ApiPath {
    /// 获取 API 路径
    /// # Example
    /// ```rust
    /// use dify_client::ApiPath;
    /// let path = ApiPath::ChatMessages;
    /// assert_eq!(path.as_str(), "/v1/chat-messages");
    /// ```
    pub fn as_str(&self) -> &'static str {
        match self {
            ApiPath::ChatMessages => "/v1/chat-messages",
            ApiPath::FilesUpload => "/v1/files/upload",
            ApiPath::ChatMessagesStop => "/v1/chat-messages/{task_id}/stop",
            ApiPath::MessagesFeedbacks => "/v1/messages/{message_id}/feedbacks",
            ApiPath::MessagesSuggested => "/v1/messages/{message_id}/suggested",
            ApiPath::Messages => "/v1/messages",
            ApiPath::Conversations => "/v1/conversations",
            ApiPath::ConversationsDelete => "/v1/conversations/{conversation_id}",
            ApiPath::ConversationsRename => "/v1/conversations/{conversation_id}/name",
            ApiPath::AudioToText => "/v1/audio-to-text",
            ApiPath::TextToAudio => "/v1/text-to-audio",
            ApiPath::Parameters => "/v1/parameters",
            ApiPath::Meta => "/v1/meta",
        }
    }
}

impl Display for ApiPath {
    fn fmt(&self, f: &mut Formatter) -> FmtResult {
        write!(f, "{}", self.as_str())
    }
}

#[derive(Clone, Debug)]
/// The configuration for the Dify client.
pub struct Config {
    /// The base URL of the Dify API.
    pub base_url: String,
    /// The API key for the Dify API.
    pub api_key: String,
    /// The timeout for the client requests.
    pub timeout: Duration,
}

/// Implements the default configuration for the client.
impl Default for Config {
    /// Returns a new instance of `ClientConfig` with default values.
    fn default() -> Self {
        Self {
            base_url: "https://api.dify.ai".into(),
            api_key: "API_KEY".into(),
            timeout: Duration::from_secs(30),
        }
    }
}

/// The `Client` struct represents a client for interacting with the Dify API.
#[derive(Clone, Debug)]
pub struct Client {
    /// The configuration for the client.
    pub config: Arc<Config>,
    /// The HTTP client for sending requests.
    pub(crate) http_client: reqwest::Client,
}

/// The `Client` struct represents a client for interacting with the Dify API.
impl Client {
    /// Creates a new `Client` instance with the specified base URL and API key.
    ///
    /// # Arguments
    ///
    /// * `base_url` - The base URL of the Dify API.
    /// * `api_key` - The API key for authentication.
    ///
    /// # Returns
    ///
    /// A new `Client` instance.
    pub fn new(base_url: &str, api_key: &str) -> Self {
        Self::new_with_config(Config {
            base_url: base_url.into(),
            api_key: api_key.into(),
            ..Config::default()
        })
    }

    /// Creates a new `Client` instance with the specified configuration.
    ///
    /// # Arguments
    ///
    /// * `c` - The configuration for the client.
    ///
    /// # Returns
    ///
    /// A new `Client` instance.
    pub fn new_with_config(c: Config) -> Self {
        let mut client = reqwest::ClientBuilder::new();
        if !c.timeout.is_zero() {
            client = client.timeout(c.timeout);
        }
        let http_client = client.build().expect("Failed to create http client");

        Self {
            config: Arc::new(c),
            http_client,
        }
    }

    /// Builds the API request URL.
    ///
    /// # Arguments
    ///
    /// * `api_path` - The API path.
    ///
    /// # Returns
    ///
    /// The request URL.
    fn build_request_api(&self, api_path: ApiPath) -> String {
        self.config.base_url.trim_end_matches("/").to_string() + api_path.as_str()
    }

    /// Sets the headers for a request with JSON content type.
    ///
    /// # Arguments
    ///
    /// * `headers` - The headers to set.
    ///
    /// # Returns
    ///
    /// A `Result` containing the request or an error.
    ///
    /// # Errors
    ///
    /// Returns an error if the headers cannot be set.
    fn set_headers_json(&self, headers: &mut HeaderMap) {
        headers.insert(CACHE_CONTROL, HeaderValue::from_static("no-cache"));
        headers.insert(
            CONTENT_TYPE,
            HeaderValue::from_static("application/json; charset=utf-8"),
        );
    }

    /// Sets the headers for a request with bearer authentication.
    ///
    /// # Arguments
    ///
    /// * `headers` - The headers to set.
    ///
    /// # Returns
    ///
    /// A `Result` containing the request or an error.
    ///
    /// # Errors
    ///
    /// Returns an error if the headers cannot be set.
    ///
    /// # Panics
    ///
    /// Panics if the API key is not set.
    fn set_headers_bearer_auth(&self, headers: &mut HeaderMap) {
        headers.insert(
            reqwest::header::AUTHORIZATION,
            HeaderValue::from_str(&format!("Bearer {}", self.config.api_key)).unwrap(),
        );
    }

    /// Creates a request with the specified URL, method, and data.
    ///
    /// # Arguments
    ///
    /// * `url` - The URL for the request.
    /// * `method` - The HTTP method for the request.
    /// * `data` - The data for the request.
    ///
    /// # Returns
    ///
    /// A `Result` containing the request or an error.
    ///
    /// # Errors
    ///
    /// Returns an error if the request cannot be created.
    ///
    /// # Panics
    ///
    /// Panics if the method is not supported.
    fn create_request(&self, url: String, method: Method, data: impl Serialize) -> Result<Request> {
        let mut headers = HeaderMap::new();
        self.set_headers_json(&mut headers);
        self.set_headers_bearer_auth(&mut headers);
        match method {
            Method::POST => {
                let r = self
                    .http_client
                    .post(url)
                    .headers(headers)
                    .json(&data)
                    .build()?;
                Ok(r)
            }
            Method::GET => {
                let r = self
                    .http_client
                    .get(url)
                    .headers(headers)
                    .query(&data)
                    .build()?;
                Ok(r)
            }
            Method::DELETE => {
                let r = self
                    .http_client
                    .delete(url)
                    .headers(headers)
                    .json(&data)
                    .build()?;
                Ok(r)
            }
            _ => {
                bail!("Method not supported");
            }
        }
    }

    /// Creates a form request with the specified URL and data.
    ///
    /// # Arguments
    ///
    /// * `url` - The URL for the request.
    /// * `data` - The data for the request.
    ///
    /// # Returns
    ///
    /// A `Result` containing the request or an error.
    fn create_multipart_request(&self, url: String, form_data: multipart::Form) -> Result<Request> {
        let mut headers = HeaderMap::new();
        self.set_headers_json(&mut headers);
        self.set_headers_bearer_auth(&mut headers);
        let r = self
            .http_client
            .post(url)
            .headers(headers)
            .multipart(form_data)
            .build()?;
        Ok(r)
    }

    /// Creates a chat message request.
    ///
    /// # Arguments
    ///
    /// * `req` - The chat message request data.
    ///
    /// # Returns
    ///
    /// A `Result` containing the request or an error.
    ///
    /// # Errors
    ///
    /// Returns an error if the request cannot be created.
    fn create_chat_message_request(&self, req: ChatMessageRequest) -> Result<Request> {
        let url = self.build_request_api(ApiPath::ChatMessages);
        self.create_request(url, Method::POST, req)
    }

    /// Sends a chat message request to the Dify API and returns the response.
    ///
    /// # Arguments
    ///
    /// * `req_data` - The chat message request data.
    ///
    /// # Returns
    ///
    /// A `Result` containing the chat message response or an error.
    pub async fn chat_messages(
        &self,
        mut req_data: ChatMessageRequest,
    ) -> Result<ChatMessageResponse> {
        req_data.response_mode = ResponseMode::Blocking;

        let req = self.create_chat_message_request(req_data)?;
        let resp = self.http_client.execute(req).await?;
        let text = resp.text().await?;
        // parse message type
        if let Ok(data) = serde_json::from_str::<ChatMessageResponse>(&text) {
            Ok(data)
        } else if let Ok(err) = serde_json::from_str::<ErrorResponse>(&text) {
            bail!(err)
        } else {
            bail!(text)
        }
    }

    /// Sends a chat message request to the Dify API and returns the response as a stream.
    /// The callback function is called for each event in the stream.
    /// The callback function should return `Some(T)` if the event is processed successfully, otherwise `None`.
    /// The function returns a vector of the processed events.
    /// The stream is stopped when the callback function returns an error or the stream ends.
    ///
    /// # Arguments
    ///
    /// * `req_data` - The chat message request data.
    /// * `callback` - The callback function to process the stream events.
    ///
    /// # Returns
    ///
    /// A `Result` containing the processed events or an error.
    ///
    /// # Errors
    ///
    /// Returns an error if the request cannot be created or the stream fails.
    pub async fn chat_messages_stream<F, T>(
        &self,
        mut req_data: ChatMessageRequest,
        callback: F,
    ) -> Result<Vec<T>>
    where
        F: Fn(ChatMessageSteamEvent) -> Result<Option<T>> + Send + Sync,
    {
        req_data.response_mode = ResponseMode::Streaming;

        let req = self.create_chat_message_request(req_data)?;
        let resp = self.http_client.execute(req).await?;
        let mut stream = resp.bytes_stream().eventsource();

        let mut ret: Vec<T> = Vec::new();
        while let Some(event) = stream.next().await {
            let event = event?;
            if event.event == "message" {
                match serde_json::from_str::<ChatMessageSteamEvent>(&event.data) {
                    Ok(msg_event) => {
                        if let Some(answer) = callback(msg_event)? {
                            ret.push(answer);
                        }
                    }
                    Err(e) => bail!("data: {}, error: {}", event.data, e),
                };
            }
        }
        Ok(ret)
    }

    /// Sends a request to upload files to the Dify API and returns the response.  
    /// 上传文件（目前仅支持图片）并在发送消息时使用，可实现图文多模态理解。  
    /// 支持 png, jpg, jpeg, webp, gif 格式。  
    /// 上传的文件仅供当前终端用户使用。  
    ///
    /// # Arguments
    ///
    /// * `req_data` - The files upload request data.
    ///
    /// # Returns
    ///
    /// A `Result` containing the files upload response or an error.
    pub async fn files_upload(&self, req_data: FilesUploadRequest) -> Result<FilesUploadResponse> {
        if !infer::is_image(&req_data.file) {
            bail!("FilesUploadRequest.File Illegal");
        }
        let kind = infer::get(&req_data.file).expect("Failed to get file type");
        let file_part = multipart::Part::stream(req_data.file)
            .file_name(format!("image_file.{}", kind.extension()))
            .mime_str(kind.mime_type())?;
        let form = multipart::Form::new()
            .text("user", req_data.user)
            .part("file", file_part);

        let url = self.build_request_api(ApiPath::FilesUpload);
        let req = self.create_multipart_request(url, form)?;
        let resp = self.http_client.execute(req).await?;
        let text = resp.text().await?;
        // parse message type
        if let Ok(data) = serde_json::from_str::<FilesUploadResponse>(&text) {
            Ok(data)
        } else if let Ok(err) = serde_json::from_str::<ErrorResponse>(&text) {
            bail!(err)
        } else {
            bail!(text)
        }
    }

    /// Sends a request to stop stream chat messages to the Dify API and returns the response.
    ///
    /// # Arguments
    ///
    /// * `req_data` - The chat message stop request data.
    ///
    /// # Returns
    ///
    /// A `Result` containing the chat message stop response or an error.
    pub async fn chat_messages_stop(
        &self,
        mut req_data: ChatMessageStopRequest,
    ) -> Result<ResultResponse> {
        if req_data.task_id.is_empty() {
            bail!("ChatMessageStopRequest.TaskId Illegal");
        }

        let url = self.build_request_api(ApiPath::ChatMessagesStop);
        let url = url.replace("{task_id}", &req_data.task_id);

        req_data.task_id = String::new();
        let req = self.create_request(url, Method::POST, req_data)?;
        let resp = self.http_client.execute(req).await?;
        let text = resp.text().await?;
        // parse message type
        if let Ok(data) = serde_json::from_str::<ResultResponse>(&text) {
            Ok(data)
        } else if let Ok(err) = serde_json::from_str::<ErrorResponse>(&text) {
            bail!(err)
        } else {
            bail!(text)
        }
    }

    /// Sends a request to retrieve suggested messages from the Dify API and returns the response.
    ///
    /// # Arguments
    ///
    /// * `req_data` - The messages suggested request data.
    ///
    /// # Returns
    ///
    /// A `Result` containing the messages suggested response or an error.
    pub async fn messages_suggested(
        &self,
        mut req_data: MessagesSuggestedRequest,
    ) -> Result<MessagesSuggestedResponse> {
        if req_data.message_id.is_empty() {
            bail!("MessagesSuggestedRequest.MessageID Illegal");
        }

        let url = self.build_request_api(ApiPath::MessagesSuggested);
        let url = url.replace("{message_id}", &req_data.message_id);
        println!("url: {}", url);

        req_data.message_id = String::new();
        let req = self.create_request(url, Method::GET, req_data)?;
        let resp = self.http_client.execute(req).await?;
        let text = resp.text().await?;
        // parse message type
        if let Ok(data) = serde_json::from_str::<MessagesSuggestedResponse>(&text) {
            Ok(data)
        } else if let Ok(err) = serde_json::from_str::<ErrorResponse>(&text) {
            bail!(err)
        } else {
            bail!(text)
        }
    }

    /// Sends a request to retrieve messages feedbacks from the Dify API and returns the response.
    ///
    /// # Arguments
    ///
    /// * `req_data` - The messages feedbacks request data.
    ///
    /// # Returns
    ///
    /// A `Result` containing the messages feedbacks response or an error.
    pub async fn messages_feedbacks(
        &self,
        mut req_data: MessagesFeedbacksRequest,
    ) -> Result<ResultResponse> {
        if req_data.message_id.is_empty() {
            bail!("MessagesFeedbacksRequest.MessageID Illegal");
        }

        let url = self.build_request_api(ApiPath::MessagesFeedbacks);
        let url = url.replace("{message_id}", &req_data.message_id);

        req_data.message_id = String::new();
        let req = self.create_request(url, Method::POST, req_data)?;
        let resp = self.http_client.execute(req).await?;
        let text = resp.text().await?;
        // parse message type
        if let Ok(data) = serde_json::from_str::<ResultResponse>(&text) {
            Ok(data)
        } else if let Ok(err) = serde_json::from_str::<ErrorResponse>(&text) {
            bail!(err)
        } else {
            bail!(text)
        }
    }

    /// Sends a request to retrieve conversations from the Dify API and returns the response.
    ///
    /// # Arguments
    ///
    /// * `req_data` - The conversations request data.
    ///
    /// # Returns
    ///
    /// A `Result` containing the conversations response or an error.
    pub async fn conversations(
        &self,
        req_data: ConversationsRequest,
    ) -> Result<ConversationsResponse> {
        if req_data.user.is_empty() {
            bail!("ConversationsRequest.User Illegal");
        }

        let url = self.build_request_api(ApiPath::Conversations);
        let req = self.create_request(url, Method::GET, req_data)?;
        let resp = self.http_client.execute(req).await?;
        let text = resp.text().await?;

        // parse message type
        if let Ok(data) = serde_json::from_str::<ConversationsResponse>(&text) {
            Ok(data)
        } else if let Ok(err) = serde_json::from_str::<ErrorResponse>(&text) {
            bail!(err)
        } else {
            bail!(text)
        }
    }

    /// Sends a request to retrieve history messages from the Dify API and returns the response.
    ///
    /// # Arguments
    ///
    /// * `req_data` - The messages request data.
    ///
    /// # Returns
    ///
    /// A `Result` containing the messages response or an error.
    pub async fn messages(&self, req_data: MessagesRequest) -> Result<MessagesResponse> {
        if req_data.conversation_id.is_empty() {
            bail!("MessagesRequest.ConversationID Illegal");
        }

        let url = self.build_request_api(ApiPath::Messages);
        let req = self.create_request(url, Method::GET, req_data)?;
        let resp = self.http_client.execute(req).await?;
        let text = resp.text().await?;
        // parse message type
        if let Ok(data) = serde_json::from_str::<MessagesResponse>(&text) {
            Ok(data)
        } else if let Ok(err) = serde_json::from_str::<ErrorResponse>(&text) {
            bail!(err)
        } else {
            bail!(text)
        }
    }

    /// Sends a request to rename a conversation in the Dify API and returns the response.
    ///
    /// # Arguments
    ///
    /// * `req_data` - The conversations rename request data.
    ///
    /// # Returns
    ///
    /// A `Result` containing the conversations rename response or an error.
    pub async fn conversations_renaming(
        &self,
        mut req_data: ConversationsRenameRequest,
    ) -> Result<ResultResponse> {
        if req_data.conversation_id.is_empty() {
            bail!("ConversationsRenameRequest.ConversationID Illegal");
        }
        if req_data.auto_generate && req_data.name.is_none() {
            bail!("ConversationsRenameRequest.Name Illegal");
        }

        let url = self.build_request_api(ApiPath::ConversationsRename);
        let url = url.replace("{conversation_id}", &req_data.conversation_id);

        req_data.conversation_id = String::new();
        let req = self.create_request(url, Method::POST, req_data)?;
        let resp = self.http_client.execute(req).await?;
        let text = resp.text().await?;
        // parse message type
        if let Ok(data) = serde_json::from_str::<ResultResponse>(&text) {
            Ok(data)
        } else if let Ok(err) = serde_json::from_str::<ErrorResponse>(&text) {
            bail!(err)
        } else {
            bail!(text)
        }
    }

    pub async fn conversations_delete(
        &self,
        mut req_data: ConversationsDeleteRequest,
    ) -> Result<()> {
        if req_data.conversation_id.is_empty() {
            bail!("ConversationsDeleteRequest.ConversationID Illegal");
        }

        let url = self.build_request_api(ApiPath::ConversationsDelete);
        let url = url.replace("{conversation_id}", &req_data.conversation_id);

        req_data.conversation_id = String::new();
        let req = self.create_request(url, Method::DELETE, req_data)?;
        let resp = self.http_client.execute(req).await?;
        // http 204 means success ?
        if resp.status().as_u16() == 204 {
            Ok(())
        } else {
            // parse message type
            let text = resp.text().await?;
            if let Ok(err) = serde_json::from_str::<ErrorResponse>(&text) {
                bail!(err)
            } else {
                bail!(text)
            }
        }
    }

    /// Sends a request to convert audio to text in the Dify API and returns the response.
    ///
    /// # Arguments
    ///
    /// * `req_data` - The audio to text request data.
    ///
    /// # Returns
    ///
    /// A `Result` containing the audio to text response or an error.
    pub async fn text_to_audio(&self, req_data: TextToAudioRequest) -> Result<Bytes> {
        if req_data.text.is_empty() {
            bail!("TextToAudioRequest.Text Illegal");
        }

        let url = self.build_request_api(ApiPath::TextToAudio);
        let req = self.create_request(url, Method::POST, req_data)?;
        let resp = self.http_client.execute(req).await?;
        // check if header is audio
        let content_type = resp.headers().get(CONTENT_TYPE);
        let content_type = content_type
            .ok_or(anyhow::anyhow!("Content-Type is missing"))?
            .to_str()?;
        // check if content_type is audio
        if content_type.starts_with("audio/") {
            let bytes = resp.bytes().await?;
            return Ok(bytes);
        }
        let text = resp.text().await?;
        if text.is_empty() {
            bail!("Content-Type is not audio/wav");
        } else if let Ok(err) = serde_json::from_str::<ErrorResponse>(&text) {
            bail!(err)
        } else {
            bail!(text)
        }
    }

    /// Sends a request to convert audio to text in the Dify API and returns the response.
    ///
    /// # Arguments
    ///
    /// * `req_data` - The audio to text request data.
    ///
    /// # Returns
    ///
    /// A `Result` containing the audio to text response or an error.
    pub async fn audio_to_text(&self, req_data: AudioToTextRequest) -> Result<AudioToTextResponse> {
        if !infer::is_audio(&req_data.file) {
            bail!("AudioToTextRequest.File Illegal");
        }
        let kind = infer::get(&req_data.file).expect("Failed to get file type");
        let file_part = multipart::Part::stream(req_data.file)
            .file_name(format!("audio_file.{}", kind.extension()))
            .mime_str(kind.mime_type())?;
        let form = multipart::Form::new()
            .text("user", req_data.user)
            .part("file", file_part);

        let url = self.build_request_api(ApiPath::AudioToText);
        let req = self.create_multipart_request(url, form)?;
        let resp = self.http_client.execute(req).await?;
        let text = resp.text().await?;
        // parse message type
        if let Ok(data) = serde_json::from_str::<AudioToTextResponse>(&text) {
            Ok(data)
        } else if let Ok(err) = serde_json::from_str::<ErrorResponse>(&text) {
            bail!(err)
        } else {
            bail!(text)
        }
    }

    /// Sends a request to retrieve parameters from the Dify API and returns the response.
    ///
    /// # Arguments
    ///
    /// * `req_data` - The parameters request data.
    ///
    /// # Returns
    ///
    /// A `Result` containing the parameters response or an error.
    pub async fn parameters(&self, req_data: ParametersRequest) -> Result<ParametersResponse> {
        if req_data.user.is_empty() {
            bail!("ParametersRequest.User Illegal");
        }

        let url = self.build_request_api(ApiPath::Parameters);
        let req = self.create_request(url, Method::GET, req_data)?;
        let resp = self.http_client.execute(req).await?;
        let text = resp.text().await?;
        // parse message type
        if let Ok(data) = serde_json::from_str::<ParametersResponse>(&text) {
            Ok(data)
        } else if let Ok(err) = serde_json::from_str::<ErrorResponse>(&text) {
            bail!(err)
        } else {
            bail!(text)
        }
    }

    /// Sends a request to retrieve meta information from the Dify API and returns the response.
    ///
    /// # Arguments
    ///
    /// * `req_data` - The meta request data.
    ///
    /// # Returns
    ///
    /// A `Result` containing the meta response or an error.
    pub async fn meta(&self, req_data: MetaRequest) -> Result<MetaResponse> {
        if req_data.user.is_empty() {
            bail!("MetaRequest.User Illegal");
        }

        let url = self.build_request_api(ApiPath::Meta);
        let req = self.create_request(url, Method::GET, req_data)?;
        let resp = self.http_client.execute(req).await?;
        let text = resp.text().await?;
        // parse message type
        if let Ok(data) = serde_json::from_str::<MetaResponse>(&text) {
            Ok(data)
        } else if let Ok(err) = serde_json::from_str::<ErrorResponse>(&text) {
            bail!(err)
        } else {
            bail!(text)
        }
    }
}