use std::ffi::OsStr;
use std::fmt;
use std::fmt::{Debug, Formatter};

use async_sqlite::rusqlite::fallible_iterator::FallibleIterator;
use async_sqlite::rusqlite::{OpenFlags, Row, named_params};
use async_sqlite::{Client, ClientBuilder, rusqlite};

use crate::persist::common::{ResultExt, concat_os_str};
use crate::persist::data_manager::DataManagerError;
use crate::views::overview::{FilmOverview, SeriesOverview};



pub struct SqliteManager {
  client: Client,
}

impl SqliteManager {
  pub async fn new(data_dir: &OsStr) -> Result<SqliteManager, DataManagerError> {
    let client = create_client(data_dir).await?;
    Ok(SqliteManager { client })
  }

  // The order of the items is undefined.
  pub async fn films_overview(&self) -> Result<Vec<FilmOverview>, DataManagerError> {
    self
      .client
      .conn(|connection| {
        connection
          .prepare(
            "
              select films.uuid, films.name, films.original_name, films.release_date, films.runtime_minutes,
                coalesce(watched_status.watched, 0) as watched
              from films left join watched_status
                on films.uuid is watched_status.media_uuid
            ",
          )?
          .query(())?
          .map(row_to_film_overview)
          .collect()
      })
      .await
      .map_err(convert_error)
  }

  // The order of the items is undefined.
  pub async fn series_overview(&self) -> Result<Vec<SeriesOverview>, DataManagerError> {
    self
      .client
      .conn(|connection| {
        connection
          .prepare(
            "
              select series.uuid, series.name, series.original_name,
                min(episodes.release_date) as first_release_date
              from series, seasons, episodes
              where series.uuid is seasons.series and seasons.uuid is episodes.season
              group by series.uuid
            ",
          )?
          .query(())?
          .map(row_to_series_overview)
          .collect()
      })
      .await
      .map_err(convert_error)
  }

  pub async fn set_film_watched_status(
    &self,
    uuid: &str,
    watched: bool,
  ) -> Result<(), DataManagerError> {
    self
      .client
      .conn({
        let uuid = uuid.to_string();
        move |connection| {
          connection.execute(
            "
              insert into watched_status (media_uuid, watched)
              values (:uuid, :watched)
              on conflict (media_uuid) do
                update set watched = :watched
            ",
            named_params! { ":uuid": uuid, ":watched": watched },
          )?;
          Ok(())
        }
      })
      .await
      .map_err(convert_error)
  }
}

impl Debug for SqliteManager {
  fn fmt(&self, formatter: &mut Formatter) -> fmt::Result {
    formatter.write_str("SqliteManager { Client, Client }")
  }
}

async fn create_client(data_dir: &OsStr) -> Result<Client, DataManagerError> {
  let client = ClientBuilder::new()
    .path("")
    .flags(OpenFlags::SQLITE_OPEN_READ_WRITE | OpenFlags::SQLITE_OPEN_NO_MUTEX)
    .open()
    .await;

  let data_dir = data_dir.to_os_string();
  let client = client
    .and_then_async(async move |client| {
      client
        .conn(move |connection| {
          let shared_path_os_str = concat_os_str!(&data_dir, "/shared.sqlite");
          let shared_path = shared_path_os_str
            .to_str()
            .expect("shared database path should be valid Unicode");
          connection.execute("attach database :path as shared", &[(":path", shared_path)])?;

          let local_path_os_str = concat_os_str!(&data_dir, "/local.sqlite");
          let local_path = local_path_os_str
            .to_str()
            .expect("local database path should be valid Unicode");
          connection.execute("attach database :path as local", &[(":path", local_path)])?;

          Ok(())
        })
        .await
        .map(|()| client)
    })
    .await;

  client.map_err(convert_error)
}

fn row_to_film_overview(row: &Row) -> rusqlite::Result<FilmOverview> {
  let uuid = row.get("uuid")?;
  let name = row.get("name")?;
  let original_name = row.get("original_name")?;
  let release_date = row.get("release_date")?;
  let runtime = row.get("runtime_minutes")?;
  let watched = row.get("watched")?;

  Ok(FilmOverview {
    uuid,
    name,
    original_name,
    release_date,
    runtime,
    watched,
  })
}

fn row_to_series_overview(row: &Row) -> rusqlite::Result<SeriesOverview> {
  let uuid = row.get("uuid")?;
  let name = row.get("name")?;
  let original_name = row.get("original_name")?;
  let first_release_date = row.get("first_release_date")?;

  Ok(SeriesOverview {
    uuid,
    name,
    original_name,
    first_release_date,
  })
}

fn convert_error(async_sqlite_error: async_sqlite::Error) -> DataManagerError {
  match async_sqlite_error {
    async_sqlite::Error::Closed => {
      panic!("database connection should remain open as long as the application is running")
    }
    async_sqlite::Error::Rusqlite(rusqlite_error) => match rusqlite_error {
      rusqlite::Error::SqliteFailure(sqlite_error, _) => match sqlite_error.code {
        rusqlite::ffi::ErrorCode::CannotOpen => DataManagerError::CannotOpenDB,
        _ => {
          println!("{sqlite_error:?}");
          DataManagerError::UnknownDBError
        }
      },
      rusqlite::Error::InvalidColumnIndex(_) => {
        panic!("column indices obtained from query should exist")
      }
      rusqlite::Error::InvalidColumnName(_) => {
        panic!("column names obtained from query should exist")
      }
      rusqlite::Error::InvalidColumnType(..) => {
        panic!("values obtained from query should have a type matching their column")
      }
      rusqlite::Error::InvalidParameterCount(..) => {
        panic!("number of bound parameters should match that in the statement")
      }
      rusqlite::Error::ExecuteReturnedResults => {
        panic!("execution of statement returned data when it shouldn't")
      }
      rusqlite::Error::MultipleStatement => {
        panic!("multiple statements present when there should be one")
      }
      _ => {
        println!("{rusqlite_error:?}");
        DataManagerError::UnknownDBError
      }
    },
    _ => {
      println!("{async_sqlite_error:?}");
      DataManagerError::UnknownDBError
    }
  }
}