// Copyright (C) 2022  Aravinth Manivannan <realaravinth@batsense.net>
// SPDX-FileCopyrightText: 2023 Aravinth Manivannan <realaravinth@batsense.net>
//
// SPDX-License-Identifier: AGPL-3.0-or-later

use std::str::FromStr;

use lazy_static::lazy_static;
use serde::{Deserialize, Serialize};
use sqlx::postgres::PgPoolOptions;
use sqlx::types::time::OffsetDateTime;
use sqlx::ConnectOptions;
use sqlx::PgPool;

use crate::errors::*;

/// Connect to databse
pub enum ConnectionOptions {
    /// fresh connection
    Fresh(Fresh),
    /// existing connection
    Existing(Conn),
}

/// Use an existing database pool
pub struct Conn(pub PgPool);

pub struct Fresh {
    pub pool_options: PgPoolOptions,
    pub disable_logging: bool,
    pub url: String,
}

impl ConnectionOptions {
    async fn connect(self) -> ServiceResult<Database> {
        let pool = match self {
            Self::Fresh(fresh) => {
                let mut connect_options =
                    sqlx::postgres::PgConnectOptions::from_str(&fresh.url).unwrap();
                if fresh.disable_logging {
                    connect_options = connect_options.disable_statement_logging();
                }
                sqlx::postgres::PgConnectOptions::from_str(&fresh.url)
                    .unwrap()
                    .disable_statement_logging();
                fresh
                    .pool_options
                    .connect_with(connect_options)
                    .await
                    .unwrap()
            }

            Self::Existing(conn) => conn.0,
        };
        Ok(Database { pool })
    }
}

#[derive(Clone)]
pub struct Database {
    pub pool: PgPool,
}

#[derive(Deserialize, Serialize, Clone, Debug, Eq, PartialEq)]
pub struct JobState {
    pub name: String,
}

impl JobState {
    pub fn new(name: String) -> Self {
        Self { name }
    }
}

lazy_static! {
    pub static ref JOB_STATE_CREATE: JobState = JobState::new("job.state.create".into());
    pub static ref JOB_STATE_FINISH: JobState = JobState::new("job.state.finish".into());
    pub static ref JOB_STATE_RUNNING: JobState = JobState::new("job.state.running".into());
    pub static ref JOB_STATES: [&'static JobState; 3] =
        [&*JOB_STATE_CREATE, &*JOB_STATE_FINISH, &*JOB_STATE_RUNNING];
}

impl Database {
    pub async fn migrate(&self) -> ServiceResult<()> {
        sqlx::migrate!("./migrations/")
            .run(&self.pool)
            .await
            .unwrap();
        self.create_job_states().await?;
        Ok(())
    }

    /// check if event type exists
    async fn job_state_exists(&self, job_state: &JobState) -> ServiceResult<bool> {
        let res = sqlx::query!(
            "SELECT EXISTS (SELECT 1 from ftest_job_states WHERE name = $1)",
            job_state.name,
        )
        .fetch_one(&self.pool)
        .await
        .map_err(map_register_err)?;

        let mut resp = false;
        if let Some(x) = res.exists {
            resp = x;
        }

        Ok(resp)
    }

    async fn create_job_states(&self) -> ServiceResult<()> {
        for j in &*JOB_STATES {
            if !self.job_state_exists(j).await? {
                sqlx::query!(
                    "INSERT INTO ftest_job_states
                 (name) VALUES ($1) ON CONFLICT (name) DO NOTHING;",
                    j.name
                )
                .execute(&self.pool)
                .await
                .map_err(map_register_err)?;
            }
        }
        Ok(())
    }

    pub async fn ping(&self) -> bool {
        use sqlx::Connection;

        if let Ok(mut con) = self.pool.acquire().await {
            con.ping().await.is_ok()
        } else {
            false
        }
    }

    pub async fn add_job(&self, commit_hash: &str) -> ServiceResult<()> {
        let now = now_unix_time_stamp();

        sqlx::query!(
            "INSERT INTO ftest_jobs
                 (commit_hash, job_state, created_at)
                     VALUES ($1, (SELECT ID FROM ftest_job_states WHERE name = $2), $3)",
            commit_hash,
            &JOB_STATE_CREATE.name,
            now
        )
        .execute(&self.pool)
        .await
        .map_err(map_register_err)?;
        Ok(())
    }

    pub async fn mark_job_scheduled(&self, commit_hash: &str) -> ServiceResult<()> {
        let now = now_unix_time_stamp();
        sqlx::query!(
            "
            UPDATE
                ftest_jobs
            SET
                job_state = (SELECT ID FROM ftest_job_states WHERE name = $1),
                scheduled_at = $2
            WHERE commit_hash = $3;",
            &JOB_STATE_RUNNING.name,
            now,
            commit_hash,
        )
        .execute(&self.pool)
        .await
        .map_err(map_register_err)?;

        Ok(())
    }

    pub async fn mark_job_finished(&self, commit_hash: &str) -> ServiceResult<()> {
        let now = now_unix_time_stamp();
        sqlx::query!(
            "
            UPDATE
                ftest_jobs
            SET
                job_state = (SELECT ID FROM ftest_job_states WHERE name = $1),
                finished_at = $2
            WHERE commit_hash = $3;",
            &JOB_STATE_FINISH.name,
            now,
            commit_hash,
        )
        .execute(&self.pool)
        .await
        .map_err(map_register_err)?;

        Ok(())
    }

    pub async fn get_job(&self, commit_hash: &str) -> ServiceResult<Job> {
        let res = sqlx::query_as!(
            InnerJob,
            "
            SELECT
                ftest_jobs.ID,
                ftest_jobs.commit_hash,
                ftest_job_states.name,
                ftest_jobs.created_at,
                ftest_jobs.scheduled_at,
                ftest_jobs.finished_at

            FROM ftest_jobs
            INNER JOIN
                ftest_job_states
            ON
                ftest_job_states.ID = ftest_jobs.job_state
            WHERE
            ftest_jobs.commit_hash = $1",
            commit_hash
        )
        .fetch_one(&self.pool)
        .await
        .map_err(map_register_err)?;

        Ok(res.into())
    }

    pub async fn get_all_jobs_of_state(&self, state: &JobState) -> ServiceResult<Vec<Job>> {
        let mut res = sqlx::query_as!(
            InnerJob,
            "
            SELECT
                ftest_jobs.ID,
                ftest_jobs.commit_hash,
                ftest_job_states.name,
                ftest_jobs.created_at,
                ftest_jobs.scheduled_at,
                ftest_jobs.finished_at

            FROM ftest_jobs
            INNER JOIN
                ftest_job_states
            ON
                ftest_job_states.ID = ftest_jobs.job_state
            WHERE
                ftest_job_states.name = $1;",
            &state.name
        )
        .fetch_all(&self.pool)
        .await
        .map_err(map_register_err)?;

        let res = res.drain(0..).map(|r| r.into()).collect();

        Ok(res)
    }

    pub async fn delete_job(&self, commit_hash: &str) -> ServiceResult<()> {
        sqlx::query!(
            "
            DELETE FROM
                ftest_jobs
            WHERE commit_hash = $1;",
            commit_hash,
        )
        .execute(&self.pool)
        .await
        .map_err(map_register_err)?;

        Ok(())
    }

    pub async fn get_next_job_to_run(&self) -> ServiceResult<SchedulerJob> {
        let res = sqlx::query_as!(
            SchedulerJob,
            "SELECT
                commit_hash
            FROM
                ftest_jobs
            WHERE
                job_state = (SELECT ID FROM ftest_job_states WHERE name = $1) 
            AND
                finished_at is NULL
            AND
                scheduled_at is NULL
            ORDER BY created_at ASC;",
            &JOB_STATE_CREATE.name
        )
        .fetch_one(&self.pool)
        .await
        .map_err(map_register_err)?;
        Ok(res)
    }
}

fn now_unix_time_stamp() -> OffsetDateTime {
    OffsetDateTime::now_utc()
}

pub async fn get_db(settings: &crate::settings::Settings) -> Database {
    let pool_options = PgPoolOptions::new().max_connections(settings.database.pool);
    ConnectionOptions::Fresh(Fresh {
        pool_options,
        url: settings.database.url.clone(),
        disable_logging: !settings.debug,
    })
    .connect()
    .await
    .unwrap()
}

/// map custom row not found error to DB error
pub fn map_row_not_found_err(e: sqlx::Error, row_not_found: ServiceError) -> ServiceError {
    if let sqlx::Error::RowNotFound = e {
        row_not_found
    } else {
        map_register_err(e)
    }
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct SchedulerJob {
    pub commit_hash: String,
}

#[derive(Clone, Debug, PartialEq, Eq)]
pub struct Job {
    pub state: JobState,
    pub commit_hash: String,
    pub id: u32,
    pub created_at: OffsetDateTime,
    pub scheduled_at: Option<OffsetDateTime>,
    pub finished_at: Option<OffsetDateTime>,
}

struct InnerJob {
    name: String,
    commit_hash: String,
    id: i32,
    created_at: OffsetDateTime,
    scheduled_at: Option<OffsetDateTime>,
    finished_at: Option<OffsetDateTime>,
}

impl From<InnerJob> for Job {
    fn from(j: InnerJob) -> Self {
        Job {
            state: (JOB_STATES)
                .iter()
                .find(|d| d.name == j.name)
                .unwrap()
                .to_owned()
                .to_owned(),
            commit_hash: j.commit_hash,
            id: j.id as u32,
            created_at: j.created_at,
            scheduled_at: j.scheduled_at,
            finished_at: j.finished_at,
        }
    }
}

/// map postgres errors to [ServiceError](ServiceError) types
fn map_register_err(e: sqlx::Error) -> ServiceError {
    use sqlx::Error;
    use std::borrow::Cow;

    if let Error::Database(err) = e {
        if err.code() == Some(Cow::from("23505")) {
            let msg = err.message();
            unimplemented!("{}", msg);
        //            if msg.contains("librepages_users_name_key") {
        //                ServiceError::UsernameTaken
        //            } else {
        //                error!("{}", msg);
        //                ServiceError::InternalServerError
        //            }
        } else {
            ServiceError::InternalServerError
        }
    } else {
        ServiceError::InternalServerError
    }
}

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

    #[actix_rt::test]
    async fn db_works() {
        let settings = Settings::new().unwrap();
        let pool_options = PgPoolOptions::new().max_connections(1);
        let db = ConnectionOptions::Fresh(Fresh {
            pool_options,
            url: settings.database.url.clone(),
            disable_logging: !settings.debug,
        })
        .connect()
        .await
        .unwrap();
        assert!(db.ping().await);

        const COMMIT_HASH: &str = "pasdfasdfasdfadf";
        const COMMIT_HASH2: &str = "pasdfasdfasdfadf22";

        db.migrate().await.unwrap();

        for e in (*JOB_STATES).iter() {
            println!("checking job state {}", e.name);
            assert!(db.job_state_exists(e).await.unwrap());
        }

        let _ = db.delete_job(COMMIT_HASH).await;
        let _ = db.delete_job(COMMIT_HASH2).await;

        db.add_job(COMMIT_HASH).await.unwrap();
        let job = db.get_job(COMMIT_HASH).await.unwrap();
        db.add_job(COMMIT_HASH2).await.unwrap();
        let job2 = db.get_job(COMMIT_HASH2).await.unwrap();

        assert_eq!(
            db.get_next_job_to_run().await.unwrap().commit_hash,
            job.commit_hash
        );

        assert!(job.created_at < now_unix_time_stamp());
        assert!(job.scheduled_at.is_none());
        assert!(job.finished_at.is_none());
        assert_eq!(
            db.get_all_jobs_of_state(&*JOB_STATE_CREATE).await.unwrap(),
            vec![job, job2.clone()]
        );

        db.mark_job_scheduled(COMMIT_HASH).await.unwrap();
        let job = db.get_job(COMMIT_HASH).await.unwrap();
        assert!(job.scheduled_at.is_some());
        assert_eq!(
            db.get_all_jobs_of_state(&*JOB_STATE_RUNNING).await.unwrap(),
            vec![job]
        );

        db.mark_job_finished(COMMIT_HASH).await.unwrap();
        let job = db.get_job(COMMIT_HASH).await.unwrap();
        assert!(job.finished_at.is_some());
        assert_eq!(
            db.get_all_jobs_of_state(&*JOB_STATE_FINISH).await.unwrap(),
            vec![job]
        );
        assert_eq!(
            db.get_next_job_to_run().await.unwrap().commit_hash,
            job2.commit_hash
        );
    }
}