use std::path::Path;

use rusqlite::{Connection, ToSql};
use chrono::{DateTime, Utc};

use crate::error::{Error, Result};
use crate::models::{Entry, Meta};

pub enum DBVersion {
    Timetrap,
    Version(u16),
}

pub trait Database {
    /// This is used to create tables and insert rows
    fn execute(&mut self, query: &str, params: &[&dyn ToSql]) -> Result<()>;

    /// And this is used to retrieve data
    fn entry_query(&self, query: &str, params: &[&dyn ToSql]) -> Result<Vec<Entry>>;
    fn meta_query(&self, query: &str, params: &[&dyn ToSql]) -> Result<Vec<Meta>>;

    // ----------
    // Migrations
    // ----------
    /// Create a database in the new database format. Actually the same format
    /// just it has an entry in the meta table that indicates the database
    /// version.
    fn init(&mut self) -> Result<()> {
        self.init_old()?;
        self.execute("INSERT INTO meta (key, value) VALUES ('database_version', 1)", &[])?;

        Ok(())
    }

    /// Creates the tables for the old database format
    fn init_old(&mut self) -> Result<()> {
        self.execute("CREATE TABLE `entries`
            (
                `id` integer NOT NULL PRIMARY KEY AUTOINCREMENT,\
                `note` varchar(255),
                `start` timestamp,
                `end` timestamp,
                `sheet` varchar(255)
            )
        ", &[])?;
        self.execute("CREATE TABLE `meta`
            (
                `id` integer NOT NULL PRIMARY KEY AUTOINCREMENT,
                `key` varchar(255),
                `value` varchar(255)
            )
        ", &[])?;
        self.execute("INSERT INTO meta (key, value) VALUES ('current_sheet', 'default')", &[])?;

        Ok(())
    }

    // -------------
    // Entry queries
    // -------------
    fn entries_by_sheet(&self, sheet: &str, start: Option<DateTime<Utc>>, end: Option<DateTime<Utc>>) -> Result<Vec<Entry>> {
        match (start, end) {
            (Some(start), Some(end)) => {
                self.entry_query(
                    "select * from entries where sheet=?1 and start >= ?2 and start <= ?3 order by start asc",
                    &[&sheet, &start, &end]
                )
            }
            (Some(start), None) => {
                self.entry_query(
                    "select * from entries where sheet=?1 and start >= ?2 order by start asc",
                    &[&sheet, &start]
                )
            }
            (None, Some(end)) => {
                self.entry_query(
                    "select * from entries where sheet=?1 and start <= ?2 order by start asc",
                    &[&sheet, &end]
                )
            }
            (None, None) => {
                self.entry_query(
                    "select * from entries where sheet=?1 order by start asc",
                    &[&sheet]
                )
            }
        }
    }

    fn entries_all_visible(&self, start: Option<DateTime<Utc>>, end: Option<DateTime<Utc>>) -> Result<Vec<Entry>> {
        match (start, end) {
            (Some(start), Some(end)) => {
                self.entry_query(
                    "select * from entries where sheet not like '!_%' escape \"!\"  and start >= ?1 and start <= ?2 order by sheet asc, start asc",
                    &[&start, &end]
                )
            }
            (Some(start), None) => {
                self.entry_query(
                    "select * from entries where sheet not like '!_%' escape \"!\"  and start >= ?1 order by sheet asc, start asc",
                    &[&start]
                )
            }
            (None, Some(end)) => {
                self.entry_query(
                    "select * from entries where sheet not like '!_%' escape \"!\"  and start <= ?1 order by sheet asc, start asc",
                    &[&end]
                )
            }
            (None, None) => {
                self.entry_query(
                    "select * from entries where sheet not like '!_%' escape \"!\"  order by sheet asc, start asc",
                    &[]
                )
            }
        }
    }

    fn entries_full(&self, start: Option<DateTime<Utc>>, end: Option<DateTime<Utc>>) -> Result<Vec<Entry>> {
        match (start, end) {
            (Some(start), Some(end)) => {
                self.entry_query(
                    "select * from entries where start >= ?1 and start <= ?2 order by sheet asc, start asc",
                    &[&start, &end]
                )
            }
            (Some(start), None) => {
                self.entry_query(
                    "select * from entries where start >= ?1 order by sheet asc, start asc",
                    &[&start]
                )
            }
            (None, Some(end)) => {
                self.entry_query(
                    "select * from entries where start <= ?1 order by sheet asc, start asc",
                    &[&end]
                )
            }
            (None, None) => {
                self.entry_query(
                    "select * from entries order by sheet asc, start asc",
                    &[]
                )
            }
        }
    }

    fn entry_insert(&mut self, start: DateTime<Utc>, end: Option<DateTime<Utc>>, note: Option<String>, sheet: &str) -> Result<()> {
        self.execute("insert into entries (start, end, note, sheet) values (?1, ?2, ?3, ?4)", &[
            &start, &end, &note, &sheet,
        ])
    }

    fn entry_update(&mut self, id: u64, start: DateTime<Utc>, end: Option<DateTime<Utc>>, note: Option<String>, sheet: &str) -> Result<()> {
        self.execute("update entries set start=?2, end=?3, note=?4, sheet=?5 where id=?1", &[
            &id, &start, &end, &note, &sheet
        ])
    }

    fn entry_by_id(&self, id: u64) -> Result<Option<Entry>> {
        Ok(self.entry_query("select * from entries where id=?1", &[&id])?.into_iter().next())
    }

    fn running_entry(&self, sheet: &str) -> Result<Option<Entry>> {
        Ok(self.entry_query("select * from entries where end is null and sheet=?1", &[&sheet])?.into_iter().next())
    }

    fn last_checkout_of_sheet(&self, sheet: &str) -> Result<Option<Entry>> {
        Ok(self.entry_query("select * from entries where end is not null and sheet=?1 order by end desc limit 1", &[&sheet])?.into_iter().next())
    }

    fn delete_entry_by_id(&mut self, id: u64) -> Result<()> {
        Ok(self.execute("delete from entries where id=?1", &[&id])?)
    }

    fn delete_entries_in_sheet(&mut self, sheet: &str) -> Result<()> {
        self.execute("delete from entries where sheet=?1", &[&sheet])?;

        if let Some(last) = self.last_sheet()? {
            if last == sheet {
                self.unset_last_sheet()?;
            }
        }

        Ok(())
    }

    // Meta queries
    fn current_sheet(&self) -> Result<Option<String>> {
        let results = self.meta_query("select * from meta where key='current_sheet'", &[])?;

        Ok(results.into_iter().next().map(|m| m.value))
    }

    fn last_sheet(&self) -> Result<Option<String>> {
        let results = self.meta_query("select * from meta where key='last_sheet'", &[])?;

        Ok(results.into_iter().next().map(|m| m.value))
    }

    fn set_current_sheet(&mut self, sheet: &str) -> Result<()> {
        self.execute("DELETE FROM meta WHERE key='current_sheet'", &[])?;
        self.execute("INSERT INTO meta (key, value) VALUES ('current_sheet', ?1)", &[&sheet])?;

        Ok(())
    }

    fn set_last_sheet(&mut self, sheet: &str) -> Result<()> {
        self.execute("DELETE FROM meta WHERE key='last_sheet'", &[])?;
        self.execute("INSERT INTO meta (key, value) VALUES ('last_sheet', ?1)", &[&sheet])?;

        Ok(())
    }

    fn unset_last_sheet(&mut self) -> Result<()> {
        Ok(self.execute("delete from meta where key='last_sheet'", &[])?)
    }

    fn version(&self) -> Result<DBVersion> {
        let results = self.meta_query("select * from meta where key='database_version'", &[])?;

        if let Some(v) = results.into_iter().next().map(|m| m.value) {
            Ok(DBVersion::Version(v.parse().map_err(|_| {
                Error::CorruptedData(format!(
                    "Found value '{}' for key 'database_version' in meta table, which is not a valid integer",
                    v
                ))
            })?))
        } else {
            Ok(DBVersion::Timetrap)
        }
    }
}

pub struct SqliteDatabase {
    connection:  Connection,
}

impl SqliteDatabase {
    pub fn from_memory() -> Result<impl Database> {
        Ok(SqliteDatabase {
            connection: Connection::open_in_memory()?,
        })
    }

    pub fn from_path<P: AsRef<Path>>(path: P) -> Result<impl Database> {
        Ok(SqliteDatabase {
            connection: Connection::open(path)?,
        })
    }

    pub fn from_path_or_create<P: AsRef<Path>>(path: P) -> Result<impl Database> {
        if path.as_ref().is_file() {
            Self::from_path(path)
        } else {
            let mut db = Self::from_path(path)?;

            db.init()?;

            Ok(db)
        }
    }
}

impl Database for SqliteDatabase {
    fn execute(&mut self, query: &str, params: &[&dyn ToSql]) -> Result<()> {
        self.connection.execute(query, params)?;

        Ok(())
    }

    fn entry_query(&self, query: &str, params: &[&dyn ToSql]) -> Result<Vec<Entry>> {
        let mut stmt = self.connection.prepare(query)?;

        let entries = stmt.query_and_then(params, |row| {
            let id: u64 = row.get("id")?;
            let note = row.get("note")?;
            let sheet = row.get("sheet")?;

            let start = row.get("start").map_err(|_| {
                Error::InvalidTimeInDatabase {
                    id: id.to_string(),
                    col: "start".into(),
                }
            })?;
            let end = row.get("end").map_err(|_| {
                Error::InvalidTimeInDatabase {
                    id: id.to_string(),
                    col: "start".into(),
                }
            })?;

            Ok(Entry {
                id, note, start, end, sheet,
            })
        })?.collect();

        entries
    }

    fn meta_query(&self, query: &str, params: &[&dyn ToSql]) -> Result<Vec<Meta>> {
        let mut stmt = self.connection.prepare(query)?;

        let results = stmt.query_map(params, |row| Ok(Meta {
            id: row.get("id")?,
            key: row.get("key")?,
            value: row.get("value")?,
        }))?.filter_map(|r| r.ok()).collect();

        Ok(results)
    }
}

#[cfg(test)]
mod tests {
    use chrono::TimeZone;

    use super::*;

    #[test]
    fn test_entries_by_sheet() {
        let mut db = SqliteDatabase::from_memory().unwrap();
        db.init().unwrap();

        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(1, 0, 0), None, None, "XXX".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(1, 0, 0), None, None, "OOO".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(2, 0, 0), None, None, "XXX".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(2, 0, 0), None, None, "OOO".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(3, 0, 0), None, None, "XXX".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(3, 0, 0), None, None, "OOO".into()).unwrap();

        let start = Utc.ymd(2021, 7, 7).and_hms(1, 30, 0);
        let end = Utc.ymd(2021, 7, 7).and_hms(2, 30, 0);

        // filter by start and end
        assert_eq!(
            db.entries_by_sheet("XXX", Some(start), Some(end)).unwrap().into_iter().map(|e| e.start).collect::<Vec<_>>(),
            vec![
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
            ]
        );

        // filter only by start
        assert_eq!(
            db.entries_by_sheet("XXX", Some(start), None).unwrap().into_iter().map(|e| e.start).collect::<Vec<_>>(),
            vec![
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(3, 0, 0),
            ]
        );

        // filter only by end
        assert_eq!(
            db.entries_by_sheet("XXX", None, Some(end)).unwrap().into_iter().map(|e| e.start).collect::<Vec<_>>(),
            vec![
                Utc.ymd(2021, 7, 7).and_hms(1, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
            ]
        );

        // no filter
        assert_eq!(
            db.entries_by_sheet("XXX", None, None).unwrap().into_iter().map(|e| e.start).collect::<Vec<_>>(),
            vec![
                Utc.ymd(2021, 7, 7).and_hms(1, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(3, 0, 0),
            ]
        );
    }

    #[test]
    fn test_entries_all() {
        let mut db = SqliteDatabase::from_memory().unwrap();
        db.init().unwrap();

        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(1, 0, 0), None, None, "XXX".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(1, 0, 0), None, None, "_OO".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(2, 0, 0), None, None, "XXX".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(2, 0, 0), None, None, "_OO".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(3, 0, 0), None, None, "XXX".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(3, 0, 0), None, None, "_OO".into()).unwrap();

        let start = Utc.ymd(2021, 7, 7).and_hms(1, 30, 0);
        let end = Utc.ymd(2021, 7, 7).and_hms(2, 30, 0);

        // filter by start and end
        assert_eq!(
            db.entries_all_visible(Some(start), Some(end)).unwrap().into_iter().map(|e| e.start).collect::<Vec<_>>(),
            vec![
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
            ]
        );

        // filter only by start
        assert_eq!(
            db.entries_all_visible(Some(start), None).unwrap().into_iter().map(|e| e.start).collect::<Vec<_>>(),
            vec![
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(3, 0, 0),
            ]
        );

        // filter only by end
        assert_eq!(
            db.entries_all_visible(None, Some(end)).unwrap().into_iter().map(|e| e.start).collect::<Vec<_>>(),
            vec![
                Utc.ymd(2021, 7, 7).and_hms(1, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
            ]
        );

        // no filter
        assert_eq!(
            db.entries_all_visible(None, None).unwrap().into_iter().map(|e| e.start).collect::<Vec<_>>(),
            vec![
                Utc.ymd(2021, 7, 7).and_hms(1, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(3, 0, 0),
            ]
        );
    }

    #[test]
    fn test_entries_full() {
        let mut db = SqliteDatabase::from_memory().unwrap();
        db.init().unwrap();

        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(1, 0, 0), None, None, "XXX".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(1, 0, 0), None, None, "_OO".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(2, 0, 0), None, None, "XXX".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(2, 0, 0), None, None, "_OO".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(3, 0, 0), None, None, "XXX".into()).unwrap();
        db.entry_insert(Utc.ymd(2021, 7, 7).and_hms(3, 0, 0), None, None, "_OO".into()).unwrap();

        let start = Utc.ymd(2021, 7, 7).and_hms(1, 30, 0);
        let end = Utc.ymd(2021, 7, 7).and_hms(2, 30, 0);

        // filter by start and end
        assert_eq!(
            db.entries_full(Some(start), Some(end)).unwrap().into_iter().map(|e| e.start).collect::<Vec<_>>(),
            vec![
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
            ]
        );

        // filter only by start
        assert_eq!(
            db.entries_full(Some(start), None).unwrap().into_iter().map(|e| e.start).collect::<Vec<_>>(),
            vec![
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(3, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(3, 0, 0),
            ]
        );

        // filter only by end
        assert_eq!(
            db.entries_full(None, Some(end)).unwrap().into_iter().map(|e| e.start).collect::<Vec<_>>(),
            vec![
                Utc.ymd(2021, 7, 7).and_hms(1, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(1, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
            ]
        );

        // no filter
        assert_eq!(
            db.entries_full(None, None).unwrap().into_iter().map(|e| e.start).collect::<Vec<_>>(),
            vec![
                Utc.ymd(2021, 7, 7).and_hms(1, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(3, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(1, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(2, 0, 0),
                Utc.ymd(2021, 7, 7).and_hms(3, 0, 0),
            ]
        );
    }
}