use crate::api::methods::sync::SyncResponse;
use reqwest::Client as reqwest_client;
use reqwest::{
    header::{HeaderMap, HeaderValue, CONTENT_TYPE, USER_AGENT},
    StatusCode,
};
use std::{collections::HashMap, error::Error, fmt, time};
use url::{ParseError, Url};

const V2_API_PATH: &str = "/_matrix/client/r0";

#[derive(Debug)]
pub enum MatrixParseError {
    ParseError(ParseError),
    EmptyScheme,
}

pub enum PresenceState {
    Offline,
    Online,
    Unavailable,
}

impl From<ParseError> for MatrixParseError {
    fn from(parse_error: ParseError) -> Self {
        MatrixParseError::ParseError(parse_error)
    }
}

#[derive(Debug)]
pub struct ResponseError {
    code: StatusCode,
    content: String,
}

impl fmt::Display for ResponseError {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        write!(formatter, "{}: {}", self.code, self.content)
    }
}

impl Error for ResponseError {}

pub enum MatrixHTTPMethod {
    Get,
    Put,
    Delete,
    Post,
}

#[derive(Debug)]
pub struct Client {
    homeserver_url: String,
    access_token: Option<String>,
    mxid: Option<String>,
    default_492_wait_ms: u64,
    use_auth_header: bool,
    reqwest_client: reqwest_client,
}

impl Client {
    pub fn new(
        homeserver_url: &str,
        access_token: Option<String>,
        mxid: Option<String>,
        default_492_wait_ms: Option<u64>,
        use_auth_header: Option<bool>,
    ) -> Result<Self, MatrixParseError> {
        let url = Url::parse(homeserver_url)?;
        if url.scheme().is_empty() {
            return Err(MatrixParseError::EmptyScheme);
        }

        Ok(Client {
            homeserver_url: homeserver_url.to_string(),
            access_token,
            mxid,
            default_492_wait_ms: default_492_wait_ms.unwrap_or_else(|| 5000),
            use_auth_header: use_auth_header.unwrap_or_else(|| true),
            reqwest_client: reqwest_client::new(),
        })
    }

    /// Sends an API request to the homeserver using the specified method and
    /// path, returning either an error or the response text.
    ///
    /// The header will automatically be populated with a user agent and have
    /// the content type set to `application/json`. If a token was provided, it
    /// will be used as a bearer auth header or as a query.
    ///
    /// This is a blocking, synchronous send. If the response from the
    /// homeserver indicates that too many requests were sent, it will attempt
    /// to wait the specified duration (or a provided default) before retrying.
    fn send(
        &self,
        method: MatrixHTTPMethod,
        path: Option<&str>,
        content: Option<String>,
        query_params: Option<HashMap<String, String>>,
        headers: Option<HeaderMap>,
    ) -> Result<String, Box<dyn std::error::Error>> {
        let mut query_params = query_params.unwrap_or_default();
        let mut headers = headers.unwrap_or_default();
        let endpoint = &format!(
            "{}{}",
            self.homeserver_url,
            path.unwrap_or_else(|| V2_API_PATH),
        );
        let mut request = match method {
            MatrixHTTPMethod::Get => self.reqwest_client.get(endpoint),
            MatrixHTTPMethod::Put => self.reqwest_client.put(endpoint),
            MatrixHTTPMethod::Delete => self.reqwest_client.delete(endpoint),
            MatrixHTTPMethod::Post => self.reqwest_client.post(endpoint),
        };

        if !headers.contains_key(&USER_AGENT) {
            let user_agent = &format!("libmatrix-client/{}", env!("CARGO_PKG_VERSION"));
            headers.insert(USER_AGENT, HeaderValue::from_str(user_agent)?);
        }

        if !headers.contains_key(&CONTENT_TYPE) {
            headers.insert(CONTENT_TYPE, HeaderValue::from_str("application/json")?);
        }

        if let Some(token) = &self.access_token {
            if self.use_auth_header {
                request = request.bearer_auth(token);
            } else {
                query_params.insert("access_token".to_string(), token.to_string());
            }
        }

        if let Some(id) = &self.mxid {
            query_params.insert("user_id".to_string(), id.to_string());
        }

        request = request.headers(headers).query(&query_params);

        if let Some(content) = content {
            request = request.body(content);
        }

        loop {
            let mut res = request
                .try_clone()
                .expect("Unable to clone request")
                .send()?;

            if res.status().is_success() {
                return Ok(res.text()?);
            } else if res.status() == StatusCode::TOO_MANY_REQUESTS {
                let mut body: HashMap<String, String> = res.json()?;
                if let Some(value) = body.get("error") {
                    body = serde_json::from_str(value)?;
                }

                if let Some(value) = body.get("retry_after_ms") {
                    std::thread::sleep(time::Duration::from_millis(value.parse::<u64>()?));
                } else {
                    std::thread::sleep(time::Duration::from_millis(self.default_492_wait_ms));
                }
            } else {
                return Err(Box::from(ResponseError {
                    code: res.status(),
                    content: res.text()?,
                }));
            }
        }
    }

    fn send_query(
        &self,
        method: MatrixHTTPMethod,
        path: &str,
        query_params: HashMap<String, String>,
    ) -> Result<String, Box<dyn Error>> {
        self.send(method, Some(path), None, Some(query_params), None)
    }

    pub fn sync(
        &self,
        bookmark_token: Option<&str>,
        timeout_ms: Option<u64>,
        filter: Option<&str>,
        get_full_state: Option<bool>,
        set_presence: Option<PresenceState>,
    ) -> Result<SyncResponse, Box<dyn Error>> {
        let mut params: HashMap<String, String> = HashMap::with_capacity(5);
        params.insert(
            "timeout".to_string(),
            timeout_ms.unwrap_or_else(|| 30000).to_string(),
        );

        if let Some(token) = bookmark_token {
            params.insert("since".to_string(), token.to_string());
        }

        if let Some(filter) = filter {
            params.insert("filter".to_string(), filter.to_string());
        }

        if let Some(true) = get_full_state {
            params.insert("full_state".to_string(), "true".to_string());
        }

        params.insert(
            "full_state".to_string(),
            match set_presence {
                Some(PresenceState::Online) => "online",
                Some(PresenceState::Unavailable) => "unavailable",
                None | Some(PresenceState::Offline) => "offline",
            }
            .to_string(),
        );

        Ok(serde_json::from_str(&self.send_query(
            MatrixHTTPMethod::Get,
            "/sync",
            params,
        )?)?)
    }
}

#[derive(Default)]
pub struct ApiError {}

impl fmt::Display for ApiError {
    fn fmt(&self, formatter: &mut fmt::Formatter) -> fmt::Result {
        write!(formatter, "an error occurred!")
    }
}