// Copyright 2023 Greptime Team
//
// 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 api::v1::alter_expr::Kind;
use api::v1::region::region_request::Body;
use api::v1::region::{
    alter_request, AddColumn, AddColumns, AlterRequest, DropColumn, DropColumns, RegionColumnDef,
    RegionRequest, RegionRequestHeader,
};
use common_telemetry::tracing_context::TracingContext;
use snafu::OptionExt;
use store_api::storage::RegionId;
use table::metadata::RawTableInfo;

use crate::ddl::alter_table::AlterTableProcedure;
use crate::error::{InvalidProtoMsgSnafu, Result};

impl AlterTableProcedure {
    /// Makes alter region request.
    pub(crate) fn make_alter_region_request(&self, region_id: RegionId) -> Result<RegionRequest> {
        // Safety: Checked in `AlterTableProcedure::new`.
        let alter_kind = self.data.task.alter_table.kind.as_ref().unwrap();
        // Safety: checked
        let table_info = self.data.table_info().unwrap();
        let kind = create_proto_alter_kind(table_info, alter_kind)?;

        Ok(RegionRequest {
            header: Some(RegionRequestHeader {
                tracing_context: TracingContext::from_current_span().to_w3c(),
                ..Default::default()
            }),
            body: Some(Body::Alter(AlterRequest {
                region_id: region_id.as_u64(),
                schema_version: table_info.ident.version,
                kind,
            })),
        })
    }
}

/// Creates region proto alter kind from `table_info` and `alter_kind`.
///
/// Returns the kind and next column id if it adds new columns.
fn create_proto_alter_kind(
    table_info: &RawTableInfo,
    alter_kind: &Kind,
) -> Result<Option<alter_request::Kind>> {
    match alter_kind {
        Kind::AddColumns(x) => {
            let mut next_column_id = table_info.meta.next_column_id;

            let add_columns = x
                .add_columns
                .iter()
                .map(|add_column| {
                    let column_def =
                        add_column
                            .column_def
                            .as_ref()
                            .context(InvalidProtoMsgSnafu {
                                err_msg: "'column_def' is absent",
                            })?;

                    let column_id = next_column_id;
                    next_column_id += 1;

                    let column_def = RegionColumnDef {
                        column_def: Some(column_def.clone()),
                        column_id,
                    };

                    Ok(AddColumn {
                        column_def: Some(column_def),
                        location: add_column.location.clone(),
                    })
                })
                .collect::<Result<Vec<_>>>()?;

            Ok(Some(alter_request::Kind::AddColumns(AddColumns {
                add_columns,
            })))
        }
        Kind::ChangeColumnTypes(x) => Ok(Some(alter_request::Kind::ChangeColumnTypes(x.clone()))),
        Kind::DropColumns(x) => {
            let drop_columns = x
                .drop_columns
                .iter()
                .map(|x| DropColumn {
                    name: x.name.clone(),
                })
                .collect::<Vec<_>>();

            Ok(Some(alter_request::Kind::DropColumns(DropColumns {
                drop_columns,
            })))
        }
        Kind::RenameTable(_) => Ok(None),
    }
}

#[cfg(test)]
mod tests {
    use std::collections::HashMap;
    use std::sync::Arc;

    use api::v1::add_column_location::LocationType;
    use api::v1::alter_expr::Kind;
    use api::v1::region::region_request::Body;
    use api::v1::region::RegionColumnDef;
    use api::v1::{
        region, AddColumn, AddColumnLocation, AddColumns, AlterExpr, ChangeColumnType,
        ChangeColumnTypes, ColumnDataType, ColumnDef as PbColumnDef, SemanticType,
    };
    use common_catalog::consts::{DEFAULT_CATALOG_NAME, DEFAULT_SCHEMA_NAME};
    use store_api::storage::{RegionId, TableId};

    use crate::ddl::alter_table::AlterTableProcedure;
    use crate::ddl::test_util::columns::TestColumnDefBuilder;
    use crate::ddl::test_util::create_table::{
        build_raw_table_info_from_expr, TestCreateTableExprBuilder,
    };
    use crate::ddl::DdlContext;
    use crate::key::table_route::TableRouteValue;
    use crate::peer::Peer;
    use crate::rpc::ddl::AlterTableTask;
    use crate::rpc::router::{Region, RegionRoute};
    use crate::test_util::{new_ddl_context, MockDatanodeManager};

    async fn prepare_ddl_context() -> (DdlContext, u64, TableId, RegionId, String) {
        let datanode_manager = Arc::new(MockDatanodeManager::new(()));
        let ddl_context = new_ddl_context(datanode_manager);
        let cluster_id = 1;
        let table_id = 1024;
        let region_id = RegionId::new(table_id, 1);
        let table_name = "foo";

        let create_table = TestCreateTableExprBuilder::default()
            .column_defs([
                TestColumnDefBuilder::default()
                    .name("ts")
                    .data_type(ColumnDataType::TimestampMillisecond)
                    .semantic_type(SemanticType::Timestamp)
                    .build()
                    .unwrap()
                    .into(),
                TestColumnDefBuilder::default()
                    .name("host")
                    .data_type(ColumnDataType::String)
                    .semantic_type(SemanticType::Tag)
                    .build()
                    .unwrap()
                    .into(),
                TestColumnDefBuilder::default()
                    .name("cpu")
                    .data_type(ColumnDataType::Float64)
                    .semantic_type(SemanticType::Field)
                    .build()
                    .unwrap()
                    .into(),
            ])
            .table_id(table_id)
            .time_index("ts")
            .primary_keys(["host".into()])
            .table_name(table_name)
            .build()
            .unwrap()
            .into();
        let table_info = build_raw_table_info_from_expr(&create_table);

        // Puts a value to table name key.
        ddl_context
            .table_metadata_manager
            .create_table_metadata(
                table_info,
                TableRouteValue::physical(vec![RegionRoute {
                    region: Region::new_test(region_id),
                    leader_peer: Some(Peer::empty(1)),
                    follower_peers: vec![],
                    leader_status: None,
                    leader_down_since: None,
                }]),
                HashMap::new(),
            )
            .await
            .unwrap();
        (
            ddl_context,
            cluster_id,
            table_id,
            region_id,
            table_name.to_string(),
        )
    }

    #[tokio::test]
    async fn test_make_alter_region_request() {
        let (ddl_context, cluster_id, table_id, region_id, table_name) =
            prepare_ddl_context().await;

        let task = AlterTableTask {
            alter_table: AlterExpr {
                catalog_name: DEFAULT_CATALOG_NAME.to_string(),
                schema_name: DEFAULT_SCHEMA_NAME.to_string(),
                table_name,
                kind: Some(Kind::AddColumns(AddColumns {
                    add_columns: vec![AddColumn {
                        column_def: Some(PbColumnDef {
                            name: "my_tag3".to_string(),
                            data_type: ColumnDataType::String as i32,
                            is_nullable: true,
                            default_constraint: b"hello".to_vec(),
                            semantic_type: SemanticType::Tag as i32,
                            comment: String::new(),
                            ..Default::default()
                        }),
                        location: Some(AddColumnLocation {
                            location_type: LocationType::After as i32,
                            after_column_name: "my_tag2".to_string(),
                        }),
                    }],
                })),
            },
        };

        let mut procedure =
            AlterTableProcedure::new(cluster_id, table_id, task, ddl_context).unwrap();
        procedure.on_prepare().await.unwrap();
        let Some(Body::Alter(alter_region_request)) =
            procedure.make_alter_region_request(region_id).unwrap().body
        else {
            unreachable!()
        };
        assert_eq!(alter_region_request.region_id, region_id.as_u64());
        assert_eq!(alter_region_request.schema_version, 1);
        assert_eq!(
            alter_region_request.kind,
            Some(region::alter_request::Kind::AddColumns(
                region::AddColumns {
                    add_columns: vec![region::AddColumn {
                        column_def: Some(RegionColumnDef {
                            column_def: Some(PbColumnDef {
                                name: "my_tag3".to_string(),
                                data_type: ColumnDataType::String as i32,
                                is_nullable: true,
                                default_constraint: b"hello".to_vec(),
                                semantic_type: SemanticType::Tag as i32,
                                comment: String::new(),
                                ..Default::default()
                            }),
                            column_id: 3,
                        }),
                        location: Some(AddColumnLocation {
                            location_type: LocationType::After as i32,
                            after_column_name: "my_tag2".to_string(),
                        }),
                    }]
                }
            ))
        );
    }

    #[tokio::test]
    async fn test_make_alter_column_type_region_request() {
        let (ddl_context, cluster_id, table_id, region_id, table_name) =
            prepare_ddl_context().await;

        let task = AlterTableTask {
            alter_table: AlterExpr {
                catalog_name: DEFAULT_CATALOG_NAME.to_string(),
                schema_name: DEFAULT_SCHEMA_NAME.to_string(),
                table_name,
                kind: Some(Kind::ChangeColumnTypes(ChangeColumnTypes {
                    change_column_types: vec![ChangeColumnType {
                        column_name: "cpu".to_string(),
                        target_type: ColumnDataType::String as i32,
                        target_type_extension: None,
                    }],
                })),
            },
        };

        let mut procedure =
            AlterTableProcedure::new(cluster_id, table_id, task, ddl_context).unwrap();
        procedure.on_prepare().await.unwrap();
        let Some(Body::Alter(alter_region_request)) =
            procedure.make_alter_region_request(region_id).unwrap().body
        else {
            unreachable!()
        };
        assert_eq!(alter_region_request.region_id, region_id.as_u64());
        assert_eq!(alter_region_request.schema_version, 1);
        assert_eq!(
            alter_region_request.kind,
            Some(region::alter_request::Kind::ChangeColumnTypes(
                ChangeColumnTypes {
                    change_column_types: vec![ChangeColumnType {
                        column_name: "cpu".to_string(),
                        target_type: ColumnDataType::String as i32,
                        target_type_extension: None,
                    }]
                }
            ))
        );
    }
}