use std::env;
use std::path::Path;
use std::str::FromStr;

use async_trait::async_trait;
use chrono::prelude::*;
use chrono::Utc;

use itertools::Itertools;
use regex::Regex;

use fs_err as fs;
use sqlx::{
    sqlite::{SqliteConnectOptions, SqliteJournalMode, SqlitePool, SqlitePoolOptions, SqliteRow},
    Result, Row,
};

use super::history::History;
use super::ordering;
use super::settings::{FilterMode, SearchMode};

pub struct Context {
    session: String,
    cwd: String,
    hostname: String,
}

pub fn current_context() -> Context {
    let session =
        env::var("ATUIN_SESSION").expect("failed to find ATUIN_SESSION - check your shell setup");
    let hostname = format!("{}:{}", whoami::hostname(), whoami::username());
    let cwd = match env::current_dir() {
        Ok(dir) => dir.display().to_string(),
        Err(_) => String::from(""),
    };

    Context {
        session,
        hostname,
        cwd,
    }
}

#[async_trait]
pub trait Database {
    async fn save(&mut self, h: &History) -> Result<()>;
    async fn save_bulk(&mut self, h: &[History]) -> Result<()>;

    async fn load(&self, id: &str) -> Result<History>;
    async fn list(
        &self,
        filter: FilterMode,
        context: &Context,
        max: Option<usize>,
        unique: bool,
    ) -> Result<Vec<History>>;
    async fn range(
        &self,
        from: chrono::DateTime<Utc>,
        to: chrono::DateTime<Utc>,
    ) -> Result<Vec<History>>;

    async fn update(&self, h: &History) -> Result<()>;
    async fn history_count(&self) -> Result<i64>;

    async fn first(&self) -> Result<History>;
    async fn last(&self) -> Result<History>;
    async fn before(&self, timestamp: chrono::DateTime<Utc>, count: i64) -> Result<Vec<History>>;

    async fn search(
        &self,
        limit: Option<i64>,
        search_mode: SearchMode,
        filter: FilterMode,
        context: &Context,
        query: &str,
    ) -> Result<Vec<History>>;

    async fn query_history(&self, query: &str) -> Result<Vec<History>>;
}

// Intended for use on a developer machine and not a sync server.
// TODO: implement IntoIterator
pub struct Sqlite {
    pool: SqlitePool,
}

impl Sqlite {
    pub async fn new(path: impl AsRef<Path>) -> Result<Self> {
        let path = path.as_ref();
        debug!("opening sqlite database at {:?}", path);

        let create = !path.exists();
        if create {
            if let Some(dir) = path.parent() {
                fs::create_dir_all(dir)?;
            }
        }

        let opts = SqliteConnectOptions::from_str(path.as_os_str().to_str().unwrap())?
            .journal_mode(SqliteJournalMode::Wal)
            .create_if_missing(true);

        let pool = SqlitePoolOptions::new().connect_with(opts).await?;

        Self::setup_db(&pool).await?;

        Ok(Self { pool })
    }

    async fn setup_db(pool: &SqlitePool) -> Result<()> {
        debug!("running sqlite database setup");

        sqlx::migrate!("./migrations").run(pool).await?;

        Ok(())
    }

    async fn save_raw(tx: &mut sqlx::Transaction<'_, sqlx::Sqlite>, h: &History) -> Result<()> {
        sqlx::query(
            "insert or ignore into history(id, timestamp, duration, exit, command, cwd, session, hostname)
                values(?1, ?2, ?3, ?4, ?5, ?6, ?7, ?8)",
        )
        .bind(h.id.as_str())
        .bind(h.timestamp.timestamp_nanos())
        .bind(h.duration)
        .bind(h.exit)
        .bind(h.command.as_str())
        .bind(h.cwd.as_str())
        .bind(h.session.as_str())
        .bind(h.hostname.as_str())
        .execute(tx)
        .await?;

        Ok(())
    }

    fn query_history(row: SqliteRow) -> History {
        History {
            id: row.get("id"),
            timestamp: Utc.timestamp_nanos(row.get("timestamp")),
            duration: row.get("duration"),
            exit: row.get("exit"),
            command: row.get("command"),
            cwd: row.get("cwd"),
            session: row.get("session"),
            hostname: row.get("hostname"),
        }
    }
}

#[async_trait]
impl Database for Sqlite {
    async fn save(&mut self, h: &History) -> Result<()> {
        debug!("saving history to sqlite");

        let mut tx = self.pool.begin().await?;
        Self::save_raw(&mut tx, h).await?;
        tx.commit().await?;

        Ok(())
    }

    async fn save_bulk(&mut self, h: &[History]) -> Result<()> {
        debug!("saving history to sqlite");

        let mut tx = self.pool.begin().await?;

        for i in h {
            Self::save_raw(&mut tx, i).await?
        }

        tx.commit().await?;

        Ok(())
    }

    async fn load(&self, id: &str) -> Result<History> {
        debug!("loading history item {}", id);

        let res = sqlx::query("select * from history where id = ?1")
            .bind(id)
            .map(Self::query_history)
            .fetch_one(&self.pool)
            .await?;

        Ok(res)
    }

    async fn update(&self, h: &History) -> Result<()> {
        debug!("updating sqlite history");

        sqlx::query(
            "update history
                set timestamp = ?2, duration = ?3, exit = ?4, command = ?5, cwd = ?6, session = ?7, hostname = ?8
                where id = ?1",
        )
        .bind(h.id.as_str())
        .bind(h.timestamp.timestamp_nanos())
        .bind(h.duration)
        .bind(h.exit)
        .bind(h.command.as_str())
        .bind(h.cwd.as_str())
        .bind(h.session.as_str())
        .bind(h.hostname.as_str())
        .execute(&self.pool)
        .await?;

        Ok(())
    }

    // make a unique list, that only shows the *newest* version of things
    async fn list(
        &self,
        filter: FilterMode,
        context: &Context,
        max: Option<usize>,
        unique: bool,
    ) -> Result<Vec<History>> {
        debug!("listing history");

        // gotta get that query builder in soon cuz I kinda hate this
        let query = if unique {
            "where timestamp = (
                    select max(timestamp) from history
                    where h.command = history.command
                )"
        } else {
            ""
        }
        .to_string();

        let mut join = if unique { "and" } else { "where" }.to_string();

        let filter_query = match filter {
            FilterMode::Global => {
                join = "".to_string();
                "".to_string()
            }
            FilterMode::Host => format!("hostname = '{}'", context.hostname).to_string(),
            FilterMode::Session => format!("session = '{}'", context.session).to_string(),
            FilterMode::Directory => format!("cwd = '{}'", context.cwd).to_string(),
        };

        let filter = format!("{} {}", join, filter_query);

        let limit = if let Some(max) = max {
            format!("limit {}", max)
        } else {
            "".to_string()
        };

        let query = format!(
            "select * from history h
                {}
                order by timestamp desc
                {} {}",
            query, filter, limit,
        );

        let res = sqlx::query(query.as_str())
            .map(Self::query_history)
            .fetch_all(&self.pool)
            .await?;

        Ok(res)
    }

    async fn range(
        &self,
        from: chrono::DateTime<Utc>,
        to: chrono::DateTime<Utc>,
    ) -> Result<Vec<History>> {
        debug!("listing history from {:?} to {:?}", from, to);

        let res = sqlx::query(
            "select * from history where timestamp >= ?1 and timestamp <= ?2 order by timestamp asc",
        )
        .bind(from)
        .bind(to)
            .map(Self::query_history)
        .fetch_all(&self.pool)
        .await?;

        Ok(res)
    }

    async fn first(&self) -> Result<History> {
        let res =
            sqlx::query("select * from history where duration >= 0 order by timestamp asc limit 1")
                .map(Self::query_history)
                .fetch_one(&self.pool)
                .await?;

        Ok(res)
    }

    async fn last(&self) -> Result<History> {
        let res = sqlx::query(
            "select * from history where duration >= 0 order by timestamp desc limit 1",
        )
        .map(Self::query_history)
        .fetch_one(&self.pool)
        .await?;

        Ok(res)
    }

    async fn before(&self, timestamp: chrono::DateTime<Utc>, count: i64) -> Result<Vec<History>> {
        let res = sqlx::query(
            "select * from history where timestamp < ?1 order by timestamp desc limit ?2",
        )
        .bind(timestamp.timestamp_nanos())
        .bind(count)
        .map(Self::query_history)
        .fetch_all(&self.pool)
        .await?;

        Ok(res)
    }

    async fn history_count(&self) -> Result<i64> {
        let res: (i64,) = sqlx::query_as("select count(1) from history")
            .fetch_one(&self.pool)
            .await?;

        Ok(res.0)
    }

    async fn search(
        &self,
        limit: Option<i64>,
        search_mode: SearchMode,
        filter: FilterMode,
        context: &Context,
        query: &str,
    ) -> Result<Vec<History>> {
        let orig_query = query;
        let query = query.to_string().replace('*', "%"); // allow wildcard char
        let limit = limit.map_or("".to_owned(), |l| format!("limit {}", l));

        let (query_sql, query_params) = match search_mode {
            SearchMode::Prefix => ("command like ?1".to_string(), vec![format!("{}%", query)]),
            SearchMode::FullText => ("command like ?1".to_string(), vec![format!("%{}%", query)]),
            SearchMode::Fuzzy => {
                let split_regex = Regex::new(r" +").unwrap();
                let terms: Vec<&str> = split_regex.split(query.as_str()).collect();
                let mut query_sql = std::string::String::new();
                let mut query_params = Vec::with_capacity(terms.len());
                let mut was_or = false;
                for (i, query_part) in terms.into_iter().enumerate() {
                    // TODO smart case mode could be made configurable like in fzf
                    let (operator, glob) = if query_part.contains(char::is_uppercase) {
                        ("glob", '*')
                    } else {
                        ("like", '%')
                    };
                    let (is_inverse, query_part) = match query_part.strip_prefix('!') {
                        Some(stripped) => (true, stripped),
                        None => (false, query_part),
                    };
                    match query_part {
                        "|" => {
                            if !was_or {
                                query_sql.push_str(" OR ");
                                was_or = true;
                                continue;
                            } else {
                                query_params.push(format!("{glob}|{glob}"));
                            }
                        }
                        exact_prefix if query_part.starts_with('^') => query_params.push(format!(
                            "{term}{glob}",
                            term = exact_prefix.strip_prefix('^').unwrap()
                        )),
                        exact_suffix if query_part.ends_with('$') => query_params.push(format!(
                            "{glob}{term}",
                            term = exact_suffix.strip_suffix('$').unwrap()
                        )),
                        exact if query_part.starts_with('\'') => query_params.push(format!(
                            "{glob}{term}{glob}",
                            term = exact.strip_prefix('\'').unwrap()
                        )),
                        exact if is_inverse => {
                            query_params.push(format!("{glob}{term}{glob}", term = exact))
                        }
                        _ => {
                            query_params.push(query_part.split("").join(glob.to_string().as_str()))
                        }
                    }
                    if i > 0 && !was_or {
                        query_sql.push_str(" AND ");
                    }
                    if is_inverse {
                        query_sql.push_str("NOT ");
                    }
                    query_sql
                        .push_str(format!("command {} ?{}", operator, query_params.len()).as_str());
                    was_or = false;
                }
                (query_sql, query_params)
            }
        };

        let filter_sql = match filter {
            FilterMode::Global => String::from(""),
            FilterMode::Session => format!("and session = '{}'", context.session),
            FilterMode::Directory => format!("and cwd = '{}'", context.cwd),
            FilterMode::Host => format!("and hostname = '{}'", context.hostname),
        };

        let res = query_params
            .iter()
            .fold(
                sqlx::query(
                    format!(
                        "select * from history h
                                           where {}
                                           {}
                                           group by command
                                           having max(timestamp)
                                           order by timestamp desc {}",
                        query_sql.as_str(),
                        filter_sql.as_str(),
                        limit.clone()
                    )
                    .as_str(),
                ),
                |query, query_param| query.bind(query_param),
            )
            .map(Self::query_history)
            .fetch_all(&self.pool)
            .await?;

        Ok(ordering::reorder_fuzzy(search_mode, orig_query, res))
    }

    async fn query_history(&self, query: &str) -> Result<Vec<History>> {
        let res = sqlx::query(query)
            .map(Self::query_history)
            .fetch_all(&self.pool)
            .await?;

        Ok(res)
    }
}

#[cfg(test)]
mod test {
    use super::*;
    use std::time::{Duration, Instant};

    async fn assert_search_eq<'a>(
        db: &impl Database,
        mode: SearchMode,
        filter_mode: FilterMode,
        query: &str,
        expected: usize,
    ) -> Result<Vec<History>> {
        let context = Context {
            hostname: "test:host".to_string(),
            session: "beepboopiamasession".to_string(),
            cwd: "/home/ellie".to_string(),
        };

        let results = db.search(None, mode, filter_mode, &context, query).await?;

        assert_eq!(
            results.len(),
            expected,
            "query \"{}\", commands: {:?}",
            query,
            results.iter().map(|a| &a.command).collect::<Vec<&String>>()
        );
        Ok(results)
    }

    async fn assert_search_commands(
        db: &impl Database,
        mode: SearchMode,
        filter_mode: FilterMode,
        query: &str,
        expected_commands: Vec<&str>,
    ) {
        let results = assert_search_eq(db, mode, filter_mode, query, expected_commands.len())
            .await
            .unwrap();
        let commands: Vec<&str> = results.iter().map(|a| a.command.as_str()).collect();
        assert_eq!(commands, expected_commands);
    }

    async fn new_history_item(db: &mut impl Database, cmd: &str) -> Result<()> {
        let history = History::new(
            chrono::Utc::now(),
            cmd.to_string(),
            "/home/ellie".to_string(),
            0,
            1,
            Some("beep boop".to_string()),
            Some("booop".to_string()),
        );
        return db.save(&history).await;
    }

    #[tokio::test(flavor = "multi_thread")]
    async fn test_search_prefix() {
        let mut db = Sqlite::new("sqlite::memory:").await.unwrap();
        new_history_item(&mut db, "ls /home/ellie").await.unwrap();

        assert_search_eq(&db, SearchMode::Prefix, FilterMode::Global, "ls", 1)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Prefix, FilterMode::Global, "/home", 0)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Prefix, FilterMode::Global, "ls  ", 0)
            .await
            .unwrap();
    }

    #[tokio::test(flavor = "multi_thread")]
    async fn test_search_fulltext() {
        let mut db = Sqlite::new("sqlite::memory:").await.unwrap();
        new_history_item(&mut db, "ls /home/ellie").await.unwrap();

        assert_search_eq(&db, SearchMode::FullText, FilterMode::Global, "ls", 1)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::FullText, FilterMode::Global, "/home", 1)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::FullText, FilterMode::Global, "ls  ", 0)
            .await
            .unwrap();
    }

    #[tokio::test(flavor = "multi_thread")]
    async fn test_search_fuzzy() {
        let mut db = Sqlite::new("sqlite::memory:").await.unwrap();
        new_history_item(&mut db, "ls /home/ellie").await.unwrap();
        new_history_item(&mut db, "ls /home/frank").await.unwrap();
        new_history_item(&mut db, "cd /home/Ellie").await.unwrap();
        new_history_item(&mut db, "/home/ellie/.bin/rustup")
            .await
            .unwrap();

        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "ls /", 3)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "ls/", 2)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "l/h/", 2)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "/h/e", 3)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "/hmoe/", 0)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "ellie/home", 0)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "lsellie", 1)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, " ", 4)
            .await
            .unwrap();

        // single term operators
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "^ls", 2)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "'ls", 2)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "ellie$", 2)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "!^ls", 2)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "!ellie", 1)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "!ellie$", 2)
            .await
            .unwrap();

        // multiple terms
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "ls !ellie", 1)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "^ls !e$", 1)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "home !^ls", 2)
            .await
            .unwrap();
        assert_search_eq(
            &db,
            SearchMode::Fuzzy,
            FilterMode::Global,
            "'frank | 'rustup",
            2,
        )
        .await
        .unwrap();
        assert_search_eq(
            &db,
            SearchMode::Fuzzy,
            FilterMode::Global,
            "'frank | 'rustup 'ls",
            1,
        )
        .await
        .unwrap();

        // case matching
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "Ellie", 1)
            .await
            .unwrap();
    }

    #[tokio::test(flavor = "multi_thread")]
    async fn test_search_reordered_fuzzy() {
        let mut db = Sqlite::new("sqlite::memory:").await.unwrap();
        // test ordering of results: we should choose the first, even though it happened longer ago.

        new_history_item(&mut db, "curl").await.unwrap();
        new_history_item(&mut db, "corburl").await.unwrap();

        // if fuzzy reordering is on, it should come back in a more sensible order
        assert_search_commands(
            &db,
            SearchMode::Fuzzy,
            FilterMode::Global,
            "curl",
            vec!["curl", "corburl"],
        )
        .await;

        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "xxxx", 0)
            .await
            .unwrap();
        assert_search_eq(&db, SearchMode::Fuzzy, FilterMode::Global, "", 2)
            .await
            .unwrap();
    }

    #[tokio::test(flavor = "multi_thread")]
    async fn test_search_bench_dupes() {
        let context = Context {
            hostname: "test:host".to_string(),
            session: "beepboopiamasession".to_string(),
            cwd: "/home/ellie".to_string(),
        };

        let mut db = Sqlite::new("sqlite::memory:").await.unwrap();
        for _i in 1..10000 {
            new_history_item(&mut db, "i am a duplicated command")
                .await
                .unwrap();
        }
        let start = Instant::now();
        let _results = db
            .search(None, SearchMode::Fuzzy, FilterMode::Global, &context, "")
            .await
            .unwrap();
        let duration = start.elapsed();

        assert!(duration < Duration::from_secs(15));
    }
}