reinhardt_views/

list.rs

//! ListView for displaying lists of objects.

use async_trait::async_trait;
use reinhardt_core::exception::{Error, Result};
use reinhardt_db::orm::Model;
use reinhardt_http::{Request, Response};
use reinhardt_rest::serializers::{JsonSerializer, Serializer};
use serde::{Deserialize, Serialize};

use crate::core::View;
use crate::mixins::MultipleObjectMixin;

/// ListView for displaying multiple objects
pub struct ListView<T>
where
	T: Model + Serialize + for<'de> Deserialize<'de> + Send + Sync + Clone,
{
	objects: Vec<T>,
	ordering: Option<Vec<String>>,
	paginate_by: Option<usize>,
	allow_empty_flag: bool,
	context_object_name: Option<String>,
	serializer: Box<dyn Serializer<Input = T, Output = String> + Send + Sync>,
}

impl<T> Default for ListView<T>
where
	T: Model + Serialize + for<'de> Deserialize<'de> + Send + Sync + Clone + 'static,
{
	fn default() -> Self {
		Self::new()
	}
}

impl<T> ListView<T>
where
	T: Model + Serialize + for<'de> Deserialize<'de> + Send + Sync + Clone + 'static,
{
	/// Creates a new `ListView` with default settings.
	///
	/// Uses `JsonSerializer` by default. Use `with_serializer` to provide a custom serializer.
	///
	/// # Examples
	///
	/// ```
	/// use reinhardt_views::{ListView, MultipleObjectMixin};
	/// use reinhardt_db::orm::Model;
	/// use serde::{Serialize, Deserialize};
	///
	/// #[derive(Debug, Clone, Serialize, Deserialize)]
	/// struct Article {
	///     id: Option<i64>,
	///     title: String,
	/// }
	///
	/// #[derive(Clone)]
	/// struct ArticleFields;
	///
	/// impl reinhardt_db::orm::FieldSelector for ArticleFields {
	///     fn with_alias(self, _alias: &str) -> Self {
	///         self
	///     }
	/// }
	///
	/// impl Model for Article {
	///     type PrimaryKey = i64;
	///     type Fields = ArticleFields;
	///     type Objects = reinhardt_db::orm::Manager<Self>;
	///     fn table_name() -> &'static str { "articles" }
	///     fn primary_key(&self) -> Option<Self::PrimaryKey> { self.id }
	///     fn set_primary_key(&mut self, value: Self::PrimaryKey) { self.id = Some(value); }
	///     fn new_fields() -> Self::Fields { ArticleFields }
	/// }
	///
	/// let view = ListView::<Article>::new();
	/// assert!(view.get_context_object_name().is_none());
	/// ```
	pub fn new() -> Self {
		Self {
			objects: Vec::new(),
			ordering: None,
			paginate_by: None,
			allow_empty_flag: true,
			context_object_name: None,
			serializer: Box::new(JsonSerializer::<T>::new()),
		}
	}

	/// Sets a custom serializer for the view.
	///
	/// # Examples
	///
	/// ```
	/// use reinhardt_views::{ListView, MultipleObjectMixin};
	/// use reinhardt_rest::serializers::JsonSerializer;
	/// use reinhardt_db::orm::Model;
	/// use serde::{Serialize, Deserialize};
	///
	/// #[derive(Debug, Clone, Serialize, Deserialize)]
	/// struct Article {
	///     id: Option<i64>,
	///     title: String,
	/// }
	///
	/// #[derive(Clone)]
	/// struct ArticleFields;
	///
	/// impl reinhardt_db::orm::FieldSelector for ArticleFields {
	///     fn with_alias(self, _alias: &str) -> Self {
	///         self
	///     }
	/// }
	///
	/// impl Model for Article {
	///     type PrimaryKey = i64;
	///     type Fields = ArticleFields;
	///     type Objects = reinhardt_db::orm::Manager<Self>;
	///     fn table_name() -> &'static str { "articles" }
	///     fn primary_key(&self) -> Option<Self::PrimaryKey> { self.id }
	///     fn set_primary_key(&mut self, value: Self::PrimaryKey) { self.id = Some(value); }
	///     fn new_fields() -> Self::Fields { ArticleFields }
	/// }
	///
	/// let view = ListView::<Article>::new()
	///     .with_serializer(Box::new(JsonSerializer::<Article>::new()));
	/// ```
	pub fn with_serializer(
		mut self,
		serializer: Box<dyn Serializer<Input = T, Output = String> + Send + Sync>,
	) -> Self {
		self.serializer = serializer;
		self
	}
	/// Sets the list of objects to display in the view.
	///
	/// # Examples
	///
	/// ```
	/// use reinhardt_views::{ListView, MultipleObjectMixin};
	/// use reinhardt_db::orm::Model;
	/// use serde::{Serialize, Deserialize};
	///
	/// #[derive(Debug, Clone, Serialize, Deserialize)]
	/// struct Article {
	///     id: Option<i64>,
	///     title: String,
	/// }
	///
	/// #[derive(Clone)]
	/// struct ArticleFields;
	///
	/// impl reinhardt_db::orm::FieldSelector for ArticleFields {
	///     fn with_alias(self, _alias: &str) -> Self {
	///         self
	///     }
	/// }
	///
	/// impl Model for Article {
	///     type PrimaryKey = i64;
	///     type Fields = ArticleFields;
	///     type Objects = reinhardt_db::orm::Manager<Self>;
	///     fn table_name() -> &'static str { "articles" }
	///     fn primary_key(&self) -> Option<Self::PrimaryKey> { self.id }
	///     fn set_primary_key(&mut self, value: Self::PrimaryKey) { self.id = Some(value); }
	///     fn new_fields() -> Self::Fields { ArticleFields }
	/// }
	///
	/// let articles = vec![
	///     Article { id: Some(1), title: "First".to_string() },
	///     Article { id: Some(2), title: "Second".to_string() },
	/// ];
	///
	/// let view = ListView::<Article>::new()
	///     .with_objects(articles.clone());
	/// # tokio_test::block_on(async {
	/// let objects = view.get_objects().await.unwrap();
	/// assert_eq!(objects.len(), 2);
	/// assert_eq!(objects[0].title, "First");
	/// # });
	/// ```
	pub fn with_objects(mut self, objects: Vec<T>) -> Self {
		self.objects = objects;
		self
	}
	/// Sets the ordering for the object list.
	///
	/// # Examples
	///
	/// ```
	/// use reinhardt_views::{ListView, MultipleObjectMixin};
	/// use reinhardt_db::orm::Model;
	/// use serde::{Serialize, Deserialize};
	///
	/// #[derive(Debug, Clone, Serialize, Deserialize)]
	/// struct Article {
	///     id: Option<i64>,
	///     title: String,
	/// }
	///
	/// #[derive(Clone)]
	/// struct ArticleFields;
	///
	/// impl reinhardt_db::orm::FieldSelector for ArticleFields {
	///     fn with_alias(self, _alias: &str) -> Self {
	///         self
	///     }
	/// }
	///
	/// impl Model for Article {
	///     type PrimaryKey = i64;
	///     type Fields = ArticleFields;
	///     type Objects = reinhardt_db::orm::Manager<Self>;
	///     fn table_name() -> &'static str { "articles" }
	///     fn primary_key(&self) -> Option<Self::PrimaryKey> { self.id }
	///     fn set_primary_key(&mut self, value: Self::PrimaryKey) { self.id = Some(value); }
	///     fn new_fields() -> Self::Fields { ArticleFields }
	/// }
	///
	/// let view = ListView::<Article>::new()
	///     .with_ordering(vec!["-created_at".to_string(), "title".to_string()]);
	///
	/// assert_eq!(view.get_ordering(), Some(vec!["-created_at".to_string(), "title".to_string()]));
	/// ```
	pub fn with_ordering(mut self, ordering: Vec<String>) -> Self {
		self.ordering = Some(ordering);
		self
	}
	/// Sets the number of items per page.
	///
	/// # Examples
	///
	/// ```
	/// use reinhardt_views::{ListView, MultipleObjectMixin};
	/// use reinhardt_db::orm::Model;
	/// use serde::{Serialize, Deserialize};
	///
	/// #[derive(Debug, Clone, Serialize, Deserialize)]
	/// struct Article {
	///     id: Option<i64>,
	///     title: String,
	/// }
	///
	/// #[derive(Clone)]
	/// struct ArticleFields;
	///
	/// impl reinhardt_db::orm::FieldSelector for ArticleFields {
	///     fn with_alias(self, _alias: &str) -> Self {
	///         self
	///     }
	/// }
	///
	/// impl Model for Article {
	///     type PrimaryKey = i64;
	///     type Fields = ArticleFields;
	///     type Objects = reinhardt_db::orm::Manager<Self>;
	///     fn table_name() -> &'static str { "articles" }
	///     fn primary_key(&self) -> Option<Self::PrimaryKey> { self.id }
	///     fn set_primary_key(&mut self, value: Self::PrimaryKey) { self.id = Some(value); }
	///     fn new_fields() -> Self::Fields { ArticleFields }
	/// }
	///
	/// let view = ListView::<Article>::new()
	///     .with_paginate_by(25);
	///
	/// assert_eq!(view.get_paginate_by(), Some(25));
	/// ```
	pub fn with_paginate_by(mut self, paginate_by: usize) -> Self {
		self.paginate_by = Some(paginate_by);
		self
	}
	/// Sets whether to allow empty result sets.
	///
	/// When set to `false`, the view will return an error if no objects are found.
	///
	/// # Examples
	///
	/// ```
	/// use reinhardt_views::{ListView, MultipleObjectMixin};
	/// use reinhardt_db::orm::Model;
	/// use serde::{Serialize, Deserialize};
	///
	/// #[derive(Debug, Clone, Serialize, Deserialize)]
	/// struct Article {
	///     id: Option<i64>,
	///     title: String,
	/// }
	///
	/// #[derive(Clone)]
	/// struct ArticleFields;
	///
	/// impl reinhardt_db::orm::FieldSelector for ArticleFields {
	///     fn with_alias(self, _alias: &str) -> Self {
	///         self
	///     }
	/// }
	///
	/// impl Model for Article {
	///     type PrimaryKey = i64;
	///     type Fields = ArticleFields;
	///     type Objects = reinhardt_db::orm::Manager<Self>;
	///     fn table_name() -> &'static str { "articles" }
	///     fn primary_key(&self) -> Option<Self::PrimaryKey> { self.id }
	///     fn set_primary_key(&mut self, value: Self::PrimaryKey) { self.id = Some(value); }
	///     fn new_fields() -> Self::Fields { ArticleFields }
	/// }
	///
	/// let view = ListView::<Article>::new()
	///     .with_allow_empty(false);
	///
	/// assert!(!view.allow_empty());
	/// ```
	pub fn with_allow_empty(mut self, allow_empty: bool) -> Self {
		self.allow_empty_flag = allow_empty;
		self
	}
	/// Sets a custom name for the object list in the context.
	///
	/// # Examples
	///
	/// ```
	/// use reinhardt_views::{ListView, MultipleObjectMixin};
	/// use reinhardt_db::orm::Model;
	/// use serde::{Serialize, Deserialize};
	///
	/// #[derive(Debug, Clone, Serialize, Deserialize)]
	/// struct Article {
	///     id: Option<i64>,
	///     title: String,
	/// }
	///
	/// #[derive(Clone)]
	/// struct ArticleFields;
	///
	/// impl reinhardt_db::orm::FieldSelector for ArticleFields {
	///     fn with_alias(self, _alias: &str) -> Self {
	///         self
	///     }
	/// }
	///
	/// impl Model for Article {
	///     type PrimaryKey = i64;
	///     type Fields = ArticleFields;
	///     type Objects = reinhardt_db::orm::Manager<Self>;
	///     fn table_name() -> &'static str { "articles" }
	///     fn primary_key(&self) -> Option<Self::PrimaryKey> { self.id }
	///     fn set_primary_key(&mut self, value: Self::PrimaryKey) { self.id = Some(value); }
	///     fn new_fields() -> Self::Fields { ArticleFields }
	/// }
	///
	/// let view = ListView::<Article>::new()
	///     .with_context_object_name("articles");
	///
	/// assert_eq!(view.get_context_object_name(), Some("articles"));
	/// ```
	pub fn with_context_object_name(mut self, name: impl Into<String>) -> Self {
		self.context_object_name = Some(name.into());
		self
	}
}

#[async_trait]
impl<T> MultipleObjectMixin<T> for ListView<T>
where
	T: Model + Serialize + for<'de> Deserialize<'de> + Send + Sync + Clone + 'static,
{
	async fn get_objects(&self) -> Result<Vec<T>> {
		Ok(self.objects.clone())
	}

	fn get_ordering(&self) -> Option<Vec<String>> {
		self.ordering.clone()
	}

	fn allow_empty(&self) -> bool {
		self.allow_empty_flag
	}

	fn get_paginate_by(&self) -> Option<usize> {
		self.paginate_by
	}

	fn get_context_object_name(&self) -> Option<&str> {
		self.context_object_name.as_deref()
	}
}

#[async_trait]
impl<T> View for ListView<T>
where
	T: Model + Serialize + for<'de> Deserialize<'de> + Send + Sync + Clone + 'static,
{
	async fn dispatch(&self, request: Request) -> Result<Response> {
		// Handle OPTIONS method
		if request.method == "OPTIONS" {
			let methods = self.allowed_methods().join(", ");
			return Ok(Response::ok()
				.with_header("Allow", &methods)
				.with_header("Content-Type", "application/json"));
		}

		// Support GET and HEAD methods
		let is_head = request.method == "HEAD";
		if !matches!(request.method.as_str(), "GET" | "HEAD") {
			return Err(Error::MethodNotAllowed(format!(
				"Method {} not allowed",
				request.method
			)));
		}

		// Get objects
		let mut object_list = self.get_objects().await?;

		// Check if empty is allowed
		if !self.allow_empty() && object_list.is_empty() {
			return Err(Error::NotFound(
				"Empty list and allow_empty is false".to_string(),
			));
		}

		// Apply ordering if configured
		if let Some(ordering_fields) = self.get_ordering() {
			// Sort by each field in reverse order (last field is primary sort)
			for field in ordering_fields.iter().rev() {
				let (field_name, descending) = if let Some(stripped) = field.strip_prefix('-') {
					(stripped, true)
				} else {
					(field.as_str(), false)
				};

				// Use serde_json::Value for dynamic field comparison
				object_list.sort_by(|a, b| {
					let a_val = serde_json::to_value(a).unwrap_or(serde_json::Value::Null);
					let b_val = serde_json::to_value(b).unwrap_or(serde_json::Value::Null);

					// Extract field value from JSON
					let a_field = a_val.get(field_name).unwrap_or(&serde_json::Value::Null);
					let b_field = b_val.get(field_name).unwrap_or(&serde_json::Value::Null);

					// Compare based on value type
					let cmp = match (a_field, b_field) {
						(serde_json::Value::String(a), serde_json::Value::String(b)) => a.cmp(b),
						(serde_json::Value::Number(a), serde_json::Value::Number(b)) => {
							// Compare as f64 for numeric values
							let a_num = a.as_f64().unwrap_or(0.0);
							let b_num = b.as_f64().unwrap_or(0.0);
							a_num
								.partial_cmp(&b_num)
								.unwrap_or(std::cmp::Ordering::Equal)
						}
						(serde_json::Value::Bool(a), serde_json::Value::Bool(b)) => a.cmp(b),
						(serde_json::Value::Null, serde_json::Value::Null) => {
							std::cmp::Ordering::Equal
						}
						(serde_json::Value::Null, _) => std::cmp::Ordering::Less,
						(_, serde_json::Value::Null) => std::cmp::Ordering::Greater,
						_ => std::cmp::Ordering::Equal,
					};

					if descending { cmp.reverse() } else { cmp }
				});
			}
		}

		// Apply pagination if configured
		let total_count = object_list.len();
		let (paginated_objects, pagination_metadata) =
			if let Some(page_size) = self.get_paginate_by() {
				// Parse page number from query params (default to 1)
				let page: usize = request
					.query_params
					.get("page")
					.and_then(|p| p.parse().ok())
					.unwrap_or(1);

				// Validate page number
				let page = if page < 1 { 1 } else { page };

				// Calculate pagination
				let start = (page - 1) * page_size;
				let end = start + page_size;

				// Apply pagination
				let paginated = if start < object_list.len() {
					object_list[start..end.min(object_list.len())].to_vec()
				} else {
					Vec::new()
				};

				// Build pagination metadata
				let total_pages = total_count.div_ceil(page_size); // Ceiling division
				let has_next = page < total_pages;
				let has_previous = page > 1;

				let metadata = serde_json::json!({
					"count": total_count,
					"page": page,
					"page_size": page_size,
					"total_pages": total_pages,
					"next": if has_next { Some(page + 1) } else { None },
					"previous": if has_previous { Some(page - 1) } else { None },
				});

				(paginated, Some(metadata))
			} else {
				(object_list, None)
			};

		// Serialize objects
		let serialized_objects: Result<Vec<_>> = paginated_objects
			.iter()
			.map(|obj| {
				self.serializer.serialize(obj).map_err(|e| match e {
					reinhardt_rest::serializers::SerializerError::Validation(v) => {
						Error::Validation(v.to_string())
					}
					reinhardt_rest::serializers::SerializerError::Serde { message } => {
						Error::Serialization(message)
					}
					reinhardt_rest::serializers::SerializerError::Other { message } => {
						Error::Serialization(message)
					}
					_ => Error::Serialization(e.to_string()),
				})
			})
			.collect();

		let serialized_objects = serialized_objects?;

		// Build response - for HEAD, return same headers but empty body
		if is_head {
			Ok(Response::ok().with_header("Content-Type", "application/json"))
		} else {
			// If pagination is enabled, wrap results in DRF-style format
			if let Some(metadata) = pagination_metadata {
				let response_data = serde_json::json!({
					"count": metadata["count"],
					"page": metadata["page"],
					"page_size": metadata["page_size"],
					"total_pages": metadata["total_pages"],
					"next": metadata["next"],
					"previous": metadata["previous"],
					"results": serialized_objects
				});
				Response::ok().with_json(&response_data)
			} else {
				Response::ok().with_json(&serialized_objects)
			}
		}
	}
}