use reqwest::Client;
use serde::de::DeserializeOwned;
use crate::error::SQLError;
use crate::Error;
use std::fs::File;
use std::io::{Read, Write};
use std::path::Path;
use crate::types::{Atomicity, SchemaMap};

pub struct QuestDB {
    client: Client,
    url: String,
}

impl QuestDB {
    /// Creates a new connection to questdb
    ///
    /// # Example
    /// ```
    /// use questdb::QuestDB;
    /// let connection = QuestDB::new("http://192.168.1.37:9000");
    /// ```
    pub fn new(url: &str) -> Self {
        QuestDB {
            client: Client::new(),
            url: String::from(url),
        }
    }

    /// Compiles and executes the SQL query supplied
    ///
    /// # Arguments
    /// * `query` - query text. It can be multi-line, but query separator, such as ; must not be
    /// included.
    /// * `limit` - This argument is used for paging. Limit can be either in format of X, Y where X
    /// is the lower limit and Y is the upper, or just Y. For example, limit=10,20 will return row
    /// numbers 10 thru to 20 inclusive. and limit=20 will return first 20 rows, which is
    /// equivalent to limit=0,20
    /// * `count` - Instructs /exec to count rows and return this value in message header. Default
    /// value is false. There is slight performance hit for requesting row count.
    /// * `nm` - Skips metadata section of the response when true. When metadata is known and client
    /// is paging this flag should typically be set to true to reduce response size. Default value
    /// is false and metadata is included in the response.
    ///
    /// # Example
    /// ```no-test
    /// use questdb::QuestDB;
    /// use serde::{Serialize, Deserialize};
    ///
    /// #[derive(Serialize, Deserialize, Debug)]
    /// struct TestData {
    ///     id: i32,
    ///     ts: String,
    ///     temp: f64,
    ///     sensor_id: i32,
    /// }
    ///
    /// let connection = QuestDB::new("http://192.168.1.37:9000");
    /// let res = connection.exec::<TestData>("select * from readings", Some(5), None, None)
    ///     .await
    ///     .unwrap();
    /// ```
    pub async fn exec<T: DeserializeOwned>(&self, query: &str, limit: Option<usize>, count: Option<bool>, nm: Option<bool>)
        -> Result<Vec<T>, crate::error::Error>
    {
        let mut url = format!("{}/exec?query={}", self.url, query);

        // Check all the optional arguments and add them to the URL
        if let Some(l) = limit {
            url += format!("&limit={}", l).as_str();
        }
        if let Some(c) = count {
            url += format!("&count={}", c).as_str();
        }
        if let Some(n) = nm {
            url += format!("&nm={}", n).as_str();
        }

        let res = self.client.get(url.as_str())
            .send()
            .await?
            .json::<serde_json::Value>()
            .await?;

        let deserialized = match res.get("dataset") {
            Some(d) => d,
            None => {
                // The SQL failed, return an error with the error data
                let e: SQLError = serde_json::from_value(res)?;
                return Err(Error::SQLError(e));
            },
        }.to_owned();

        let deserialized: Vec<T> = serde_json::from_value(deserialized)?;

        Ok(deserialized)
    }

    /// The function `imp` streams tabular text data directly into a table. It supports CSV, TAB and
    /// Pipe (|) delimited inputs and optional headers. There are no restrictions on data size. Data
    /// type and structure is detected automatically and usually without additional configuration.
    /// However in some cases additional configuration can be provided to augment automatic
    /// detection results.
    ///
    /// # Arguments
    /// * `file_path` - Path to the file that is going to be imported
    /// * `schema` - List of columns and their types. This will overwrite the default unless the
    ///     table is already created.
    /// * `table_name` - Name of the table where the data will be saved
    /// * `overwrite` - Default value is false. Set it to true to have existing table deleted before
    ///     appending data.
    /// * `durable` - When request is durable QuestDB will flush relevant disk cache before
    ///     responding. Default value is false
    /// * `atomicity` - Available values are strict and relaxed. Default value is relaxed. When
    ///     atomicity is relaxed data rows that cannot be appended to table are discarded, thus
    ///     allowing partial uploads. In strict mode upload fails as soon as any data error is
    ///     encountered and all previously appended rows are rolled back.
    ///
    /// # Example
    /// ```no-test
    /// let connection = QuestDB::new("http://192.168.1.37:9000");
    /// let schema = new_schema!(("movieId", Schema::String), ("imdbId", Schema::Int));
    ///
    /// let res = connection.imp("./test.csv", Some(schema), "nu_table123", None, None, None)
    ///     .await
    ///     .unwrap();
    /// ```
    pub async fn imp(&self, file_path: &'static str, schema: Option<Vec<SchemaMap>>, table_name: &'static str,
                     overwrite: Option<bool>, durable: Option<bool>, atomicity: Option<Atomicity>)
        -> Result<(), crate::error::Error>
    {
        let mut form = reqwest::multipart::Form::new();
        let mut url = format!("{}/imp?fmt=json&name={}", self.url, table_name);

        // Check all the optional arguments and add them to the URL
        if let Some(s) = schema {
            let data = serde_json::to_string(&s).unwrap();
            form = form.part("schema", reqwest::multipart::Part::text(data));
        }
        if let Some(o) = overwrite {
            url += format!("&overwrite={}", o).as_str();
        }
        if let Some(d) = durable {
            url += format!("&durable={}", d).as_str();
        }
        if let Some(a) = atomicity {
            url += format!("&atomicity={}", a).as_str();
        }

        // Read the file as bytes
        let filep = Path::new(file_path);
        let mut file = File::open(&filep)?;
        let mut file_bytes: Vec<u8> = Vec::new();
        file.read_to_end(&mut file_bytes)?;

        // Create a part with the file_name
        let file_name = match filep.file_name() {
            Some(name) => name.to_str().unwrap(),
            None => filep.to_str().unwrap(),
        };
        let part = reqwest::multipart::Part::bytes(file_bytes)
            .file_name(file_name);

        // Create the form with the file part
        form = form.part("data", part);

        // Make the POST request
        let _res = self.client.post(url.as_str())
            .multipart(form)
            .send()
            .await?
            .text()
            .await?;

        Ok(())
    }

    /// Exports the result of the query to a CSV file
    ///
    /// # Arguments
    /// * `query` - query text. It can be multi-line, but query separator, such as ; must not be
    /// included.
    /// * `limit` - This argument is used for paging. Limit can be either in format of X, Y where X
    /// is the lower limit and Y is the upper, or just Y. For example, limit=10,20 will return row
    /// numbers 10 thru to 20 inclusive. and limit=20 will return first 20 rows, which is
    /// equivalent to limit=0,20
    ///
    /// # Example
    /// ```no-test
    /// use questdb::QuestDB;
    /// use std::fs::File;
    ///
    /// let connection = QuestDB::new("http://192.168.1.37:9000");
    ///
    /// let mut output_file = File::create("output.csv").unwrap();
    /// let res = match connection.exp("select * from nu_table", Some(5), &mut output_file)
    ///     .await
    ///     .unwrap();
    /// ```
    pub async fn exp(&self, query: &str, limit: Option<usize>, output_file: &mut File) -> Result<(), Error> {
        let mut url = format!("{}/exp?query={}", self.url, query);

        // Check all the optional arguments and add them to the URL
        if let Some(l) = limit {
            url += format!("&limit={}", l).as_str();
        }

        // Make the GET request
        let res: String = self.client.get(url.as_str())
            .send()
            .await?
            .text()
            .await?;

        // Try to write data to the file
        output_file.write_all(res.as_bytes())?;

        Ok(())
    }
}