sqlxgentools/lib/sqlxgentools_cli/src/generators/repositories/relations.rs

use proc_macro2::TokenStream;
use quote::{format_ident, quote};

use crate::models::{Field, FieldForeignMode, Model};

pub fn gen_get_many_by_related_entity_method(model: &Model, foreign_key_field: &Field) -> TokenStream {
    let resource_ident = format_ident!("{}", &model.name);

    let foreign_ref_params = match &foreign_key_field.foreign_mode {
        FieldForeignMode::ForeignRef(params) => params,
        FieldForeignMode::NotRef => {
            panic!("Expected foreign key");
        } 
    };

    let select_query = format!("SELECT * FROM {} WHERE {} = $1", model.table_name, foreign_key_field.name);

    let func_name_ident = format_ident!("get_many_{}_by_{}", foreign_ref_params.reverse_relation_name, foreign_ref_params.target_resource_name);

    quote! {
        pub async fn #func_name_ident(&self, item_id: &str) -> Result<Vec<#resource_ident>, sqlx::Error> {
            sqlx::query_as::<_, #resource_ident>(#select_query)
                .bind(item_id)
                .fetch_all(&self.db.0)
                .await
        }
    }
}

pub fn gen_get_many_by_related_entities_method(all_models: &[Model], model: &Model, foreign_key_field: &Field) -> TokenStream {
    let resource_ident = format_ident!("{}", &model.name);

    let foreign_ref_params = match &foreign_key_field.foreign_mode {
        FieldForeignMode::ForeignRef(params) => params,
        FieldForeignMode::NotRef => {
            panic!("Expected foreign key");
        } 
    };

    let select_query = format!("SELECT * FROM {} WHERE {} IN ({{}})", model.table_name, foreign_key_field.name);

    let target_resource = all_models.iter()
        .find(|m| m.name.to_lowercase() == foreign_ref_params.target_resource_name.to_lowercase())
        .expect("Could not find foreign ref target type associated resource");

    let func_name_ident = format_ident!("get_many_{}_by_{}", foreign_ref_params.reverse_relation_name, target_resource.table_name);

    quote! {
        pub async fn #func_name_ident(&self, items_ids: Vec<String>) -> Result<Vec<#resource_ident>, sqlx::Error> {
            if items_ids.is_empty() {
                return Ok(vec![])
            }
            let placeholder_params: String = (1..=(items_ids.len()))
                .map(|i| format!("${i}"))
                .collect::<Vec<String>>()
                .join(",");
            let query_tmpl = format!(
                #select_query,
                placeholder_params
            );
            let mut query = sqlx::query_as::<_, #resource_ident>(&query_tmpl);
            for id in items_ids {
                query = query.bind(id)
            }

            query
                .fetch_all(&self.db.0)
                .await
        }
    }
}