//! Service layer for layers.

use diesel_async::AsyncPgConnection;
use reqwest::StatusCode;
use uuid::Uuid;

use crate::model::dto::actions::{ActionType, RestoreDrawingLayerActionPayload};
use crate::model::dto::drawings::DrawingDto;
use crate::model::dto::layers::UpdateLayerDto;
use crate::model::entity::drawings::Drawing;
use crate::model::entity::Map;
use crate::model::r#enum::layer_type::LayerType;
use crate::{
    config::data::SharedPool,
    error::ServiceError,
    model::{
        dto::layers::{LayerDto, LayerSearchParameters},
        entity::layers::Layer,
    },
};

/// Search layers from the database.
///
/// # Errors
/// If the connection to the database could not be established.
pub async fn find(
    search_parameters: LayerSearchParameters,
    pool: &SharedPool,
) -> Result<Vec<LayerDto>, ServiceError> {
    let mut conn = pool.get().await?;
    let result = Layer::find(search_parameters, &mut conn).await?;
    Ok(result)
}

/// Find a layer by id in the database.
///
/// # Errors
/// If the connection to the database could not be established.
pub async fn find_by_id(id: Uuid, pool: &SharedPool) -> Result<LayerDto, ServiceError> {
    let mut conn = pool.get().await?;
    let result = Layer::find_by_id(id, &mut conn).await?;
    Ok(result.into())
}

/// Create a new layer in the database.
///
/// # Errors
/// If the connection to the database could not be established.
pub async fn create(
    map_id: i32,
    new_layer: LayerDto,
    pool: &SharedPool,
) -> Result<LayerDto, ServiceError> {
    let mut conn = pool.get().await?;
    _ = Map::find_by_id(map_id, &mut conn).await?;
    let result = Layer::create(map_id, new_layer, &mut conn).await?;
    Ok(result)
}

/// Helper that returns an error if the given layer is not on the map.
///
/// # Errors
/// If the connection to the database could not be established.
async fn assert_layer_on_map(
    map_id: i32,
    layer_id: Uuid,
    conn: &mut AsyncPgConnection,
) -> Result<(), ServiceError> {
    let layer = Layer::find_by_id(layer_id, conn).await?;
    if layer.map_id != map_id {
        return Err(ServiceError::new(
            StatusCode::CONFLICT,
            "map_id of path and dto doesn't match",
        ));
    }
    Ok(())
}

/// Helper that returns an error in case `layer_ids` isn't exactly
/// the set of all non-deleted layers on the map.
///
/// # Errors
/// If the connection to the database could not be established.
async fn assert_all_layers_on_map(
    map_id: i32,
    layer_ids: &[Uuid],
    conn: &mut AsyncPgConnection,
) -> Result<(), ServiceError> {
    let layer_ids_in_map: Vec<Uuid> = Layer::find(
        LayerSearchParameters {
            map_id: Some(map_id),
            type_: None,
            is_alternative: None,
            only_non_deleted: Some(()),
        },
        conn,
    )
    .await?
    .into_iter()
    .map(|layer| layer.id)
    .collect();

    for layer_id in layer_ids {
        if !layer_ids_in_map.contains(layer_id) {
            return Err(ServiceError::new(
                StatusCode::CONFLICT,
                "map_id of path and dto doesn't match",
            ));
        }
    }
    Ok(())
}

/// Update layers. Available updates are:
///  - renaming of one layer
///  - reordering of multiple layers
///  - restoring of one layer that is makred deleted
///
/// # Errors
/// If the connection to the database could not be established.
pub async fn update(
    map_id: i32,
    update: UpdateLayerDto,
    pool: &SharedPool,
) -> Result<ActionType, ServiceError> {
    let mut conn = pool.get().await?;

    let action = match update {
        UpdateLayerDto::Rename(dto) => {
            assert_layer_on_map(map_id, dto.id, &mut conn).await?;
            Layer::rename(dto.clone(), &mut conn).await?;
            ActionType::RenameLayer(dto)
        }
        UpdateLayerDto::Reorder(new_order) => {
            assert_all_layers_on_map(map_id, &new_order, &mut conn).await?;
            Layer::reorder(new_order.clone(), &mut conn).await?;
            ActionType::ReorderLayers(new_order)
        }
        UpdateLayerDto::RestoreDrawingLayer(dto) => {
            assert_layer_on_map(map_id, dto.id, &mut conn).await?;
            let layer = Layer::find_by_id(dto.id, &mut conn).await?;
            if layer.marked_deleted.is_none() {
                return Err(ServiceError::new(
                    StatusCode::CONFLICT,
                    "layer is not marked deleted",
                ));
            }
            Layer::restore(map_id, dto.id, &mut conn).await?;
            let drawings = Drawing::find_in_layer(dto.id, &mut conn).await?;
            let drawing_dtos = drawings
                .into_iter()
                .map(DrawingDto::try_from)
                .collect::<Result<Vec<DrawingDto>, ServiceError>>()?;
            ActionType::RestoreDrawingLayer(RestoreDrawingLayerActionPayload::new(
                dto.id,
                drawing_dtos,
            ))
        }
    };
    Ok(action)
}

/// Delete the layer in the database.
///
/// # Errors
/// If the connection to the database could not be established.
pub async fn delete_by_id(
    map_id: i32,
    layer_id: Uuid,
    pool: &SharedPool,
) -> Result<(), ServiceError> {
    let mut conn = pool.get().await?;
    let layer = Layer::find_by_id(layer_id, &mut conn).await?;
    if layer.type_ != LayerType::Drawing {
        return Err(ServiceError::new(
            StatusCode::FORBIDDEN,
            "can only delete drawing layer",
        ));
    }
    Layer::delete(map_id, layer_id, &mut conn).await?;
    Ok(())
}