use polars::error::PolarsError;
use polars::export::chrono::NaiveDate;
use polars::prelude::*;
use polars::series::Series;
use serde::Deserialize;
use std::collections::HashMap;
use std::collections::HashSet;
use std::error::Error;
use std::fs::File;

/// Response from the DataQuery API
#[derive(Deserialize, Debug)]
pub struct DQTimeSeriesResponse {
    instruments: Vec<Instrument>,
}

#[derive(Deserialize, Debug)]
pub struct DQCatalogueResponse {
    pub items: u32,
    pub catalogue_responses: Vec<DQCatalogueSingleResponse>,
    pub all_instruments: Vec<String>,
}

impl DQCatalogueResponse {
    pub fn new(catalogue_responses: Vec<DQCatalogueSingleResponse>) -> Self {
        let all_instruments: Vec<String> = catalogue_responses
            .iter()
            .flat_map(|response| {
                response
                    .instruments
                    .iter()
                    .map(|instrument| instrument.instrument_name.clone())
            })
            .collect();

        DQCatalogueResponse {
            items: all_instruments.len() as u32,
            catalogue_responses: catalogue_responses,
            all_instruments: all_instruments,
        }
    }
}

#[derive(Deserialize, Debug)]
pub struct DQCatalogueSingleResponse {
    pub links: Vec<HashMap<String, Option<String>>>,
    pub items: u32,
    pub instruments: Vec<DQCatalogueInstrument>,
}

#[derive(Deserialize, Debug)]
pub struct DQCatalogueInstrument {
    #[serde(rename = "instrument-id")]
    pub instrument_id: String,
    #[serde(rename = "instrument-name")]
    pub instrument_name: String,
    pub item: u32,
}

/// Representation of DQResponse.Instrument
#[derive(Deserialize, Debug)]
struct Instrument {
    attributes: Vec<Attribute>,
}

/// Representation of DQResponse.Instrument.Attribute
#[derive(Deserialize, Debug)]
struct Attribute {
    expression: String,
    #[serde(rename = "time-series")]
    time_series: Vec<(String, Option<f64>)>,
}

/// Representation of a single time series
#[derive(Debug)]
pub struct DQTimeSeries {
    expression: String,
    time_series: Vec<(String, Option<f64>)>,
}

#[derive(Debug)]
pub struct JPMaQSIndicator {
    pub df: DataFrame,
    pub ticker: String,
    pub metrics: Vec<String>,
}

impl DQTimeSeries {
    /// Get the ticker from the expression
    pub fn get_ticker(&self) -> Result<String, Box<dyn Error>> {
        if !self.expression.starts_with("DB(JPMAQS,") {
            return Err("Expression does not start with 'DB(JPMAQS,'".into());
        }
        let ticker = self.expression.split(',').nth(1).unwrap();
        if ticker.is_empty() {
            return Err("Ticker is empty".into());
        }
        Ok(ticker.to_string())
    }

    /// Get the metric from the expression
    pub fn get_metric(&self) -> Result<String, Box<dyn Error>> {
        if !self.expression.starts_with("DB(JPMAQS,") {
            return Err("Expression does not start with 'DB(JPMAQS,'".into());
        }
        let metric = self
            .expression
            .trim_end_matches(')')
            .split(',')
            .last()
            .unwrap();
        if metric.is_empty() {
            return Err("Metric is empty".into());
        }
        Ok(metric.to_string())
    }

    /// Convert the time series to a Polars DataFrame
    pub fn to_dataframe(&self) -> Result<DataFrame, PolarsError> {
        let dates: Vec<NaiveDate> = self
            .time_series
            .iter()
            .map(|(date_str, _)| NaiveDate::parse_from_str(date_str, "%Y%m%d").unwrap())
            .collect();

        let values: Vec<Option<f64>> = self.time_series.iter().map(|(_, value)| *value).collect();
        let date_series = Series::new("date".into(), &dates);
        let value_series = Float64Chunked::new("value".into(), &values);

        df!(
            "real_date" => date_series,
            self.expression.clone() => value_series
        )
    }
}

impl DQTimeSeriesResponse {
    /// Return a list of all expressions in the response
    pub fn list_expressions(&self) -> Vec<String> {
        self.instruments
            .iter()
            .flat_map(|instrument| {
                instrument
                    .attributes
                    .iter()
                    .map(|attribute| attribute.expression.clone())
            })
            .collect()
    }

    /// Return a list of all DQTimeSeries in the response
    pub fn get_all_timeseries(&self) -> Vec<DQTimeSeries> {
        self.instruments
            .iter()
            .flat_map(|instrument| {
                instrument.attributes.iter().map(|attribute| DQTimeSeries {
                    expression: attribute.expression.clone(),
                    time_series: attribute.time_series.clone(),
                })
            })
            .collect()
    }

    /// Return a list of lists of DQTimeSeries, where each list contains all the timeseries for each ticker
    pub fn get_timeseries_by_ticker(&self) -> Vec<Vec<DQTimeSeries>> {
        let timeseries_by_ticker = self
            .instruments
            .iter()
            .flat_map(|instrument| {
                instrument.attributes.iter().map(|attribute| DQTimeSeries {
                    expression: attribute.expression.clone(),
                    time_series: attribute.time_series.clone(),
                })
            })
            .fold(HashMap::new(), |mut acc, ts| {
                let ticker = ts.get_ticker().unwrap();
                acc.entry(ticker).or_insert_with(Vec::new).push(ts);
                acc
            });

        timeseries_by_ticker.into_iter().map(|(_, v)| v).collect()
    }
}

impl JPMaQSIndicator {
    pub fn new(timeseries_list: Vec<DQTimeSeries>) -> Result<Self, Box<dyn Error>> {
        let found_tickers = timeseries_list
            .iter()
            .map(|ts| ts.get_ticker().unwrap())
            .collect::<HashSet<String>>();
        if found_tickers.len() != 1 {
            return Err("All provided timeseries do not belong to the same ticker".into());
        }
        let ticker = found_tickers.into_iter().next().unwrap();
        let metrics = timeseries_list
            .iter()
            .map(|ts| ts.get_metric().unwrap())
            .collect::<Vec<String>>();

        let output_df = timeseries_list_to_dataframe(timeseries_list, true)?;

        Ok(JPMaQSIndicator {
            df: output_df,
            ticker: ticker,
            metrics: metrics,
        })
    }

    pub fn as_qdf(&self) -> Result<DataFrame, Box<dyn Error>> {
        let mut qdf = self.df.clone();
        let (cid, xcat) = match self.ticker.split_once('_') {
            Some((cid, xcat)) => (cid, xcat),
            None => return Err(format!("Invalid ticker format; got '{}'", self.ticker).into()),
        };
        qdf.with_column(Series::new("cid".into(), vec![cid; qdf.height()]))?;
        qdf.with_column(Series::new("xcat".into(), vec![xcat; qdf.height()]))?;

        sort_qdf_columns(&mut qdf)?;

        Ok(qdf)
    }

    pub fn save_qdf_to_csv(&self, filename: &str) -> Result<(), Box<dyn Error>> {
        save_qdf_to_csv(&mut self.as_qdf()?, filename)
    }
}

fn timeseries_list_to_dataframe(
    timeseries_list: Vec<DQTimeSeries>,
    dropna: bool,
) -> Result<DataFrame, Box<dyn Error>> {
    let mut output_df = DataFrame::new(vec![]).expect("Failed to create DataFrame");

    if let Some((first, rest)) = timeseries_list.split_first() {
        // Convert the first timeseries to DataFrame and clone it to avoid modifying the original
        let mut result_df = {
            let mut df = first
                .to_dataframe()
                .expect("Failed to convert first timeseries to DataFrame");
            let curr_metric = first.get_metric().expect("Failed to get metric");
            let column_name = df.get_column_names()[1].to_string();
            df.rename(&column_name, curr_metric.into())
                .expect("Failed to rename column");
            df.clone()
        };

        // Iterate over the remaining timeseries
        for ts in rest {
            // Convert the current timeseries to DataFrame
            let mut df = ts
                .to_dataframe()
                .expect("Failed to convert timeseries to DataFrame");

            // Rename the metric column to the metric of the relevant DataFrame
            let curr_metric = ts.get_metric().expect("Failed to get metric");
            let column_name = df.get_column_names()[1].to_string();
            df.rename(&column_name, curr_metric.into())
                .expect("Failed to rename column");

            // Perform a left join on the 'real_date' column
            result_df = result_df
                .left_join(&df, ["real_date"], ["real_date"])
                .expect("Left join failed");
        }

        output_df = result_df.clone();
    } else {
        println!("No timeseries provided.");
    }

    // drop rows where all values are NA
    if dropna {
        output_df = output_df
            .lazy()
            .drop_nulls(None)
            .filter(all_horizontal([all().is_not_null()])?)
            .collect()
            .expect("Failed to drop NA rows");
    }

    Ok(output_df)
}

fn sort_qdf_columns(qdf: &mut DataFrame) -> Result<(), Box<dyn Error>> {
    let index_columns = ["real_date", "cid", "xcat"];
    let known_metrics = ["value", "grading", "eop_lag", "mop_lag"];

    let df_columns = qdf
        .get_column_names()
        .into_iter()
        .map(|s| s.clone().into_string())
        .collect::<Vec<String>>();

    let mut unknown_metrics: Vec<String> = df_columns
        .iter()
        .filter(|&m| !known_metrics.contains(&m.as_str()))
        .filter(|&m| !index_columns.contains(&m.as_str()))
        .cloned()
        .collect();

    let mut new_columns: Vec<String> = vec![];
    new_columns.extend(index_columns.iter().map(|s| s.to_string()));
    for &colname in &known_metrics {
        if df_columns.contains(&colname.into()) {
            new_columns.push(colname.to_string());
        }
    }

    unknown_metrics.sort();
    new_columns.extend(unknown_metrics);
    *qdf = qdf
        .select(new_columns.clone())
        .expect("Failed to select columns");

    Ok(())
}

fn save_qdf_to_csv(qdf: &mut DataFrame, filename: &str) -> Result<(), Box<dyn Error>> {
    let file = File::create(filename)?;

    // Write the DataFrame to a CSV file
    let mut csv_writer = CsvWriter::new(file);
    csv_writer.finish(qdf)?;

    Ok(())
}

#[allow(dead_code)]
fn main() {
    let json_data = r#"
    {
        "instruments": [
            {
                "attributes": [
                    {
                        "expression": "metric, TICKER, metric1()",
                        "time-series": [
                            ["2022-01-01", 10.0],
                            ["2022-01-02", null]
                        ]
                    },
                    {
                        "expression": "metric, TICKER2, metric2()",
                        "time-series": [
                            ["2022-01-01", 20.0],
                            ["2022-01-03", 25.0]
                        ]
                    }
                ]
            },
            {
                "attributes": [
                    {
                        "expression": "metric, TICKER3, metric3()",
                        "time-series": [
                            ["2022-02-01", 30.0],
                            ["2022-02-02", 35.0]
                        ]
                    }
                ]
            }
        ]
    }
    "#;

    let response: DQTimeSeriesResponse = serde_json::from_str(json_data).unwrap();
    println!("{:?}", response);

    let all_timeseries = response.get_all_timeseries();
    for ts in all_timeseries {
        println!("{:?}", ts);
        match ts.to_dataframe() {
            Ok(df) => println!("{:?}", df),
            Err(e) => println!("Failed to create DataFrame: {:?}", e),
        }
    }
}