// Copyright 2022 RisingWave Labs
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
//     http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.

use std::time::Duration;

use indexmap::IndexMap;
use itertools::Itertools;
use risingwave_sqlparser::ast::Statement;
use risingwave_sqlparser::parser::Parser;
use shell_words::split;
use sqllogictest::{DBOutput, DefaultColumnType};

use crate::ctl_ext::start_ctl;

/// A RisingWave client.
pub struct RisingWave {
    client: tokio_postgres::Client,
    task: tokio::task::JoinHandle<()>,
    host: String,
    dbname: String,
    /// The `SET` statements that have been executed on this client.
    /// We need to replay them when reconnecting.
    set_stmts: SetStmts,
}

/// `SetStmts` stores and compacts all `SET` statements that have been executed in the client
/// history.
#[derive(Default)]
pub struct SetStmts {
    // variable name -> last set statement
    stmts: IndexMap<String, String>,
}

impl SetStmts {
    fn push(&mut self, sql: &str) {
        let ast = Parser::parse_sql(sql).expect("a set statement should be parsed successfully");
        match Itertools::exactly_one(ast.into_iter()).expect("should contain only one statement") {
            // record `local` for variable and `SetTransaction` if supported in the future.
            Statement::SetVariable {
                local: _,
                variable,
                value: _,
            } => {
                let key = variable.real_value().to_lowercase();
                // store complete sql as value.
                self.stmts.insert(key, sql.to_owned());
            }
            _ => unreachable!(),
        }
    }

    fn replay_iter(&self) -> impl Iterator<Item = &str> + '_ {
        self.stmts.values().map(|s| s.as_str())
    }
}

impl RisingWave {
    pub async fn connect(
        host: String,
        dbname: String,
    ) -> Result<Self, tokio_postgres::error::Error> {
        let set_stmts = SetStmts::default();
        let (client, task) = Self::connect_inner(&host, &dbname, &set_stmts).await?;
        Ok(Self {
            client,
            task,
            host,
            dbname,
            set_stmts,
        })
    }

    pub async fn connect_inner(
        host: &str,
        dbname: &str,
        set_stmts: &SetStmts,
    ) -> Result<(tokio_postgres::Client, tokio::task::JoinHandle<()>), tokio_postgres::error::Error>
    {
        let (client, connection) = tokio_postgres::Config::new()
            .host(host)
            .port(4566)
            .dbname(dbname)
            .user("root")
            .connect_timeout(Duration::from_secs(5))
            .connect(tokio_postgres::NoTls)
            .await?;
        let task = tokio::spawn(async move {
            if let Err(e) = connection.await {
                tracing::error!("postgres connection error: {e}");
            }
        });
        // replay all SET statements
        for stmt in set_stmts.replay_iter() {
            client.simple_query(stmt).await?;
        }
        Ok((client, task))
    }

    pub async fn reconnect(&mut self) -> Result<(), tokio_postgres::error::Error> {
        let (client, task) = Self::connect_inner(&self.host, &self.dbname, &self.set_stmts).await?;
        self.client = client;
        self.task = task;
        Ok(())
    }

    /// Returns a reference of the inner Postgres client.
    pub fn pg_client(&self) -> &tokio_postgres::Client {
        &self.client
    }
}

impl Drop for RisingWave {
    fn drop(&mut self) {
        self.task.abort();
    }
}

fn parse_risedev_ctl_args(command: &std::process::Command) -> Option<Vec<String>> {
    let program = command.get_program().to_str()?;
    if program != "bash" && !program.ends_with("/bash") {
        return None;
    }

    let mut args = command.get_args();
    if args.next()?.to_str()? != "-c" {
        return None;
    }
    let script = args.next()?.to_str()?;
    if args.next().is_some() {
        return None;
    }

    let mut parts = split(script).ok()?;
    if parts.len() < 2 || parts[0] != "./risedev" || parts[1] != "ctl" {
        return None;
    }
    Some(parts.split_off(2))
}

fn command_output(exit_code: i32, stderr: Vec<u8>) -> std::process::Output {
    #[cfg(unix)]
    {
        use std::os::unix::process::ExitStatusExt;

        std::process::Output {
            status: std::process::ExitStatus::from_raw(exit_code << 8),
            stdout: vec![],
            stderr,
        }
    }

    #[cfg(not(unix))]
    {
        unimplemented!("simulation mode does not support non-unix platforms")
    }
}

#[async_trait::async_trait]
impl sqllogictest::AsyncDB for RisingWave {
    type ColumnType = DefaultColumnType;
    type Error = tokio_postgres::error::Error;

    async fn run(&mut self, sql: &str) -> Result<DBOutput<Self::ColumnType>, Self::Error> {
        use sqllogictest::DBOutput;

        if self.client.is_closed() {
            // connection error, reset the client
            self.reconnect().await?;
        }

        if sql.trim_start().to_lowercase().starts_with("set") {
            self.set_stmts.push(sql);
        }

        let mut output = vec![];

        let rows = self.client.simple_query(sql).await?;
        let mut cnt = 0;
        for row in rows {
            let mut row_vec = vec![];
            match row {
                tokio_postgres::SimpleQueryMessage::Row(row) => {
                    for i in 0..row.len() {
                        match row.get(i) {
                            Some(v) => {
                                if v.is_empty() {
                                    row_vec.push("(empty)".to_owned());
                                } else {
                                    row_vec.push(v.to_owned());
                                }
                            }
                            None => row_vec.push("NULL".to_owned()),
                        }
                    }
                }
                tokio_postgres::SimpleQueryMessage::CommandComplete(cnt_) => {
                    cnt = cnt_;
                    break;
                }
                _ => unreachable!(),
            }
            output.push(row_vec);
        }

        if output.is_empty() {
            Ok(DBOutput::StatementComplete(cnt))
        } else {
            Ok(DBOutput::Rows {
                types: vec![DefaultColumnType::Any; output[0].len()],
                rows: output,
            })
        }
    }

    async fn shutdown(&mut self) {}

    fn engine_name(&self) -> &str {
        "risingwave"
    }

    async fn sleep(dur: Duration) {
        tokio::time::sleep(dur).await
    }

    async fn run_command(command: std::process::Command) -> std::io::Result<std::process::Output> {
        if let Some(ctl_args) = parse_risedev_ctl_args(&command) {
            let output = match start_ctl(ctl_args).await {
                Ok(()) => command_output(0, vec![]),
                Err(err) => command_output(1, format!("{err:#}\n").into_bytes()),
            };
            return Ok(output);
        }
        unimplemented!("spawning process is not supported in simulation mode")
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn command_output_uses_exit_code_and_stderr() {
        let output = command_output(1, b"ctl failed\n".to_vec());

        assert!(!output.status.success());
        assert_eq!(output.status.code(), Some(1));
        assert_eq!(output.stderr, b"ctl failed\n");
    }
}
