/*!
This module defines the main API wrapper.
*/

use log::{debug, LevelFilter};
use rorm_declaration::config::DatabaseDriver;
use rorm_sql::delete::Delete;
use rorm_sql::insert::Insert;
use rorm_sql::join_table::JoinTableData;
use rorm_sql::ordering::OrderByEntry;
use rorm_sql::select::Select;
use rorm_sql::select_column::SelectColumnData;
use rorm_sql::update::Update;
use rorm_sql::value::Value;
use rorm_sql::{conditional, value, DBImpl};

use crate::error::Error;
use crate::executor::{AffectedRows, All, Executor, Nothing, One, QueryStrategy};
use crate::internal;
use crate::query_type::GetLimitClause;
use crate::row::Row;
use crate::transaction::Transaction;

/**
Type alias for [`SelectColumnData`]..

As all databases use currently the same fields, a type alias is sufficient.
*/
pub type ColumnSelector<'a> = SelectColumnData<'a>;

/**
Type alias for [`JoinTableData`].

As all databases use currently the same fields, a type alias is sufficient.
*/
pub type JoinTable<'until_build, 'post_build> = JoinTableData<'until_build, 'post_build>;

/**
Configuration to create a database connection.

`min_connections` and `max_connections` must be greater than 0
and `max_connections` must be greater or equals `min_connections`.
 */
#[derive(Debug, serde::Serialize, serde::Deserialize)]
pub struct DatabaseConfiguration {
    /// The driver and its corresponding settings
    pub driver: DatabaseDriver,
    /// Minimal connections to initialize upfront.
    pub min_connections: u32,
    /// Maximum connections that allowed to be created.
    pub max_connections: u32,
    /// If set to true, logging will be completely disabled.
    ///
    /// In case of None, false will be used.
    pub disable_logging: Option<bool>,
    /// Set the log level of SQL statements
    ///
    /// In case of None, [`LevelFilter::Debug`] will be used.
    pub statement_log_level: Option<LevelFilter>,
    /// Log level in case of slow statements (>300 ms)
    ///
    /// In case of None, [`LevelFilter::Warn`] will be used.
    pub slow_statement_log_level: Option<LevelFilter>,
}

impl DatabaseConfiguration {
    /**
    Create a new database configuration with some defaults set.

    **Defaults**:
    - `min_connections`: 1
    - `max_connections`: 10
    - `disable_logging`: None
    - `statement_log_level`: [`Some`] of [`LevelFilter::Debug`]
    - `slow_statement_log_level`: [`Some`] of [`LevelFilter::Warn`]

    **Parameter**:
    - `driver`: [`DatabaseDriver`]: Configuration of the database driver.
    */
    pub fn new(driver: DatabaseDriver) -> Self {
        DatabaseConfiguration {
            driver,
            min_connections: 1,
            max_connections: 10,
            disable_logging: None,
            statement_log_level: Some(LevelFilter::Debug),
            slow_statement_log_level: Some(LevelFilter::Warn),
        }
    }
}

/**
Main API wrapper.

All operations can be started with methods of this struct.
 */
#[derive(Clone)]
pub struct Database {
    pub(crate) pool: internal::database::Impl,
    pub(crate) db_impl: DBImpl,
}

impl Database {
    /**
    Connect to the database using `configuration`.
     */
    pub async fn connect(configuration: DatabaseConfiguration) -> Result<Self, Error> {
        internal::database::connect(configuration).await
    }

    /**
    Execute raw SQL statements on the database.

    If possible, the statement is executed as prepared statement.

    To bind parameter, use ? as placeholder in SQLite and MySQL
    and $1, $2, $n in Postgres.

    **Parameter**:
    - `query_string`: Reference to a valid SQL query.
    - `bind_params`: Optional list of values to bind in the query.
    - `transaction`: Optional transaction to execute the query on.

    **Returns** a list of rows. If there are no values to retrieve, an empty
    list is returned.
     */
    pub async fn raw_sql<'a>(
        &self,
        query_string: &'a str,
        bind_params: Option<&[value::Value<'a>]>,
        transaction: Option<&mut Transaction>,
    ) -> Result<Vec<Row>, Error> {
        internal::database::raw_sql(self, query_string, bind_params, transaction).await
    }

    /**
    Entry point for a [`Transaction`].
     */
    pub async fn start_transaction(&self) -> Result<Transaction, Error> {
        internal::database::start_transaction(self).await
    }
}

/**
This method is used to retrieve rows that match the provided query.

It is generic over a [`QueryStrategy`] which specifies how and how many rows to query.

**Parameter**:
- `model`: Model to query.
- `columns`: Columns to retrieve values from.
- `joins`: Join tables expressions.
- `conditions`: Optional conditions to apply.
- `limit`: Optional limit / offset to apply to the query.
    Depending on the query strategy, this is either [`LimitClause`](rorm_sql::limit_clause::LimitClause)
    (for [`All`] and [`Stream`](crate::executor::Stream))
    or a simple [`u64`] (for [`One`] and [`Optional`](crate::executor::Optional)).
- `transaction`: Optional transaction to execute the query on.
 */
#[allow(clippy::too_many_arguments)]
pub fn query<'result, 'db: 'result, 'post_query: 'result, Q: QueryStrategy + GetLimitClause>(
    executor: impl Executor<'db>,
    model: &str,
    columns: &[ColumnSelector<'_>],
    joins: &[JoinTable<'_, 'post_query>],
    conditions: Option<&conditional::Condition<'post_query>>,
    order_by_clause: &[OrderByEntry<'_>],
    limit: Option<Q::LimitOrOffset>,
) -> Q::Result<'result> {
    let columns: Vec<_> = columns
        .iter()
        .map(|c| {
            executor.dialect().select_column(
                c.table_name,
                c.column_name,
                c.select_alias,
                c.aggregation,
            )
        })
        .collect();
    let joins: Vec<_> = joins
        .iter()
        .map(|j| {
            executor
                .dialect()
                .join_table(j.join_type, j.table_name, j.join_alias, j.join_condition)
        })
        .collect();
    let mut q = executor
        .dialect()
        .select(&columns, model, &joins, order_by_clause);

    if let Some(condition) = conditions {
        q = q.where_clause(condition);
    }

    if let Some(limit) = Q::get_limit_clause(limit) {
        q = q.limit_clause(limit);
    }

    let (query_string, bind_params) = q.build();

    debug!("SQL: {}", query_string);

    executor.execute::<Q>(query_string, bind_params)
}

/**
This method is used to insert into a table.

**Parameter**:
- `model`: Table to insert to
- `columns`: Columns to set `values` for.
- `values`: Values to bind to the corresponding columns.
- `transaction`: Optional transaction to execute the query on.
 */
pub async fn insert_returning(
    executor: impl Executor<'_>,
    model: &str,
    columns: &[&str],
    values: &[Value<'_>],
    returning: &[&str],
) -> Result<Row, Error> {
    generic_insert::<One>(executor, model, columns, values, Some(returning)).await
}

/**
This method is used to insert into a table.

**Parameter**:
- `model`: Table to insert to
- `columns`: Columns to set `values` for.
- `values`: Values to bind to the corresponding columns.
- `transaction`: Optional transaction to execute the query on.
 */
pub async fn insert(
    executor: impl Executor<'_>,
    model: &str,
    columns: &[&str],
    values: &[Value<'_>],
) -> Result<(), Error> {
    generic_insert::<Nothing>(executor, model, columns, values, None).await
}

/// Generic implementation of:
/// - [`Database::insert`]
/// - [`Database::insert_returning`]
pub(crate) fn generic_insert<'result, 'db: 'result, 'post_query: 'result, Q: QueryStrategy>(
    executor: impl Executor<'db>,
    model: &str,
    columns: &[&str],
    values: &[Value<'post_query>],
    returning: Option<&[&str]>,
) -> Q::Result<'result> {
    let values = &[values];
    let q = executor.dialect().insert(model, columns, values, returning);

    let (query_string, bind_params): (_, Vec<Value<'post_query>>) = q.build();

    debug!("SQL: {}", query_string);

    executor.execute::<Q>(query_string, bind_params)
}

/**
This method is used to bulk insert rows.

If one insert statement fails, the complete operation will be rolled back.

**Parameter**:
- `model`: Table to insert to
- `columns`: Columns to set `rows` for.
- `rows`: List of values to bind to the corresponding columns.
- `transaction`: Optional transaction to execute the query on.
 */
pub async fn insert_bulk(
    executor: impl Executor<'_>,
    model: &str,
    columns: &[&str],
    rows: &[&[Value<'_>]],
) -> Result<(), Error> {
    let mut guard = executor.ensure_transaction().await?;
    let tr: &mut Transaction = guard.get_transaction();

    for chunk in rows.chunks(25) {
        let mut insert = tr.dialect().insert(model, columns, chunk, None);
        insert = insert.rollback_transaction();
        let (insert_query, insert_params) = insert.build();

        debug!("SQL: {}", insert_query);

        tr.execute::<Nothing>(insert_query, insert_params).await?;
    }

    guard.commit().await?;
    Ok(())
}

/**
This method is used to bulk insert rows.

If one insert statement fails, the complete operation will be rolled back.

**Parameter**:
- `model`: Table to insert to
- `columns`: Columns to set `rows` for.
- `rows`: List of values to bind to the corresponding columns.
- `transaction`: Optional transaction to execute the query on.
 */
pub async fn insert_bulk_returning(
    executor: impl Executor<'_>,
    model: &str,
    columns: &[&str],
    rows: &[&[Value<'_>]],
    returning: &[&str],
) -> Result<Vec<Row>, Error> {
    let mut guard = executor.ensure_transaction().await?;
    let tr: &mut Transaction = guard.get_transaction();

    let mut inserted = Vec::with_capacity(rows.len());
    for chunk in rows.chunks(25) {
        let mut insert = tr.dialect().insert(model, columns, chunk, Some(returning));
        insert = insert.rollback_transaction();
        let (insert_query, insert_params) = insert.build();

        debug!("SQL: {}", insert_query);

        inserted.extend(tr.execute::<All>(insert_query, insert_params).await?);
    }

    guard.commit().await?;

    Ok(inserted)
}

/**
This method is used to delete rows from a table.

**Parameter**:
- `model`: Name of the model to delete rows from
- `condition`: Optional condition to apply.
- `transaction`: Optional transaction to execute the query on.

**Returns** the rows affected of the delete statement. Note that this also includes
relations, etc.
 */
pub async fn delete<'post_build>(
    executor: impl Executor<'_>,
    model: &str,
    condition: Option<&conditional::Condition<'post_build>>,
) -> Result<u64, Error> {
    let mut q = executor.dialect().delete(model);
    if condition.is_some() {
        q = q.where_clause(condition.unwrap());
    }

    let (query_string, bind_params) = q.build();

    debug!("SQL: {}", query_string);

    executor
        .execute::<AffectedRows>(query_string, bind_params)
        .await
}

/**
This method is used to update rows in a table.

**Parameter**:
- `model`: Name of the model to update rows from
- `updates`: A list of updates. An update is a tuple that consists of a list of columns to
update as well as the value to set to the columns.
- `condition`: Optional condition to apply.
- `transaction`: Optional transaction to execute the query on.

**Returns** the rows affected from the update statement. Note that this also includes
relations, etc.
 */
pub async fn update<'post_build>(
    executor: impl Executor<'_>,
    model: &str,
    updates: &[(&str, Value<'post_build>)],
    condition: Option<&conditional::Condition<'post_build>>,
) -> Result<u64, Error> {
    let mut stmt = executor.dialect().update(model);

    for (column, value) in updates {
        stmt = stmt.add_update(column, *value);
    }

    if let Some(cond) = condition {
        stmt = stmt.where_clause(cond);
    }

    let (query_string, bind_params) = stmt.build()?;
    debug!("SQL: {}", query_string);

    executor
        .execute::<AffectedRows>(query_string, bind_params)
        .await
}

#[cfg(test)]
mod test {
    use futures::future::BoxFuture;

    use crate::{database, Database, Error, Row};

    #[allow(unused)]
    fn should_compile(db: &'static Database) {
        let fut = database::insert_bulk_returning(db, "", &[], &[], &[]);
        let fut: BoxFuture<'_, Result<Vec<Row>, Error>> = Box::pin(fut);
        drop(fut);
    }
}