use crate::context::Data;
use crate::extensions::{BoxExtension, Extension, Extensions};
use crate::model::__DirectiveLocation;
use crate::parser::parse_query;
use crate::query::{QueryBuilder, StreamResponse};
use crate::registry::{MetaDirective, MetaInputValue, Registry};
use crate::subscription::{create_connection, create_subscription_stream, SubscriptionTransport};
use crate::types::QueryRoot;
use crate::validation::{check_rules, CheckResult, ValidationMode};
use crate::{
    CacheControl, Error, ObjectType, Pos, QueryEnv, QueryError, QueryResponse, Result,
    SubscriptionType, Type, Variables, ID,
};
use async_graphql_parser::query::{Document, OperationType};
use bytes::Bytes;
use futures::channel::mpsc;
use futures::Stream;
use indexmap::map::IndexMap;
use itertools::Itertools;
use std::any::Any;
use std::ops::Deref;
use std::sync::atomic::AtomicUsize;
use std::sync::Arc;

/// Schema builder
pub struct SchemaBuilder<Query, Mutation, Subscription> {
    validation_mode: ValidationMode,
    query: QueryRoot<Query>,
    mutation: Mutation,
    subscription: Subscription,
    registry: Registry,
    data: Data,
    complexity: Option<usize>,
    depth: Option<usize>,
    extensions: Vec<Box<dyn Fn() -> BoxExtension + Send + Sync>>,
}

impl<Query: ObjectType, Mutation: ObjectType, Subscription: SubscriptionType>
    SchemaBuilder<Query, Mutation, Subscription>
{
    /// You can use this function to register types that are not directly referenced.
    pub fn register_type<T: Type>(mut self) -> Self {
        T::create_type_info(&mut self.registry);
        self
    }

    /// Disable introspection query
    pub fn disable_introspection(mut self) -> Self {
        self.query.disable_introspection = true;
        self
    }

    /// Set limit complexity, Default no limit.
    pub fn limit_complexity(mut self, complexity: usize) -> Self {
        self.complexity = Some(complexity);
        self
    }

    /// Set limit complexity, Default no limit.
    pub fn limit_depth(mut self, depth: usize) -> Self {
        self.depth = Some(depth);
        self
    }

    /// Add an extension
    pub fn extension<F: Fn() -> E + Send + Sync + 'static, E: Extension>(
        mut self,
        extension_factory: F,
    ) -> Self {
        self.extensions
            .push(Box::new(move || Box::new(extension_factory())));
        self
    }

    /// Add a global data that can be accessed in the `Schema`, you access it with `Context::data`.
    pub fn data<D: Any + Send + Sync>(mut self, data: D) -> Self {
        self.data.insert(data);
        self
    }

    /// Set the validation mode, default is `ValidationMode::Strict`.
    pub fn validation_mode(mut self, validation_mode: ValidationMode) -> Self {
        self.validation_mode = validation_mode;
        self
    }

    /// Build schema.
    pub fn finish(self) -> Schema<Query, Mutation, Subscription> {
        Schema(Arc::new(SchemaInner {
            validation_mode: self.validation_mode,
            query: self.query,
            mutation: self.mutation,
            subscription: self.subscription,
            complexity: self.complexity,
            depth: self.depth,
            extensions: self.extensions,
            env: SchemaEnv(Arc::new(SchemaEnvInner {
                registry: self.registry,
                data: self.data,
            })),
        }))
    }
}

#[doc(hidden)]
pub struct SchemaEnvInner {
    pub registry: Registry,
    pub data: Data,
}

#[doc(hidden)]
#[derive(Clone)]
pub struct SchemaEnv(Arc<SchemaEnvInner>);

impl Deref for SchemaEnv {
    type Target = SchemaEnvInner;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

#[doc(hidden)]
pub struct SchemaInner<Query, Mutation, Subscription> {
    pub(crate) validation_mode: ValidationMode,
    pub(crate) query: QueryRoot<Query>,
    pub(crate) mutation: Mutation,
    pub(crate) subscription: Subscription,
    pub(crate) complexity: Option<usize>,
    pub(crate) depth: Option<usize>,
    pub(crate) extensions: Vec<Box<dyn Fn() -> BoxExtension + Send + Sync>>,
    pub(crate) env: SchemaEnv,
}

/// GraphQL schema
pub struct Schema<Query, Mutation, Subscription>(Arc<SchemaInner<Query, Mutation, Subscription>>);

impl<Query, Mutation, Subscription> Clone for Schema<Query, Mutation, Subscription> {
    fn clone(&self) -> Self {
        Schema(self.0.clone())
    }
}

impl<Query, Mutation, Subscription> Deref for Schema<Query, Mutation, Subscription>
where
    Query: ObjectType + Send + Sync + 'static,
    Mutation: ObjectType + Send + Sync + 'static,
    Subscription: SubscriptionType + Send + Sync + 'static,
{
    type Target = SchemaInner<Query, Mutation, Subscription>;

    fn deref(&self) -> &Self::Target {
        &self.0
    }
}

impl<Query, Mutation, Subscription> Schema<Query, Mutation, Subscription>
where
    Query: ObjectType + Send + Sync + 'static,
    Mutation: ObjectType + Send + Sync + 'static,
    Subscription: SubscriptionType + Send + Sync + 'static,
{
    /// Create a schema builder
    ///
    /// The root object for the query and Mutation needs to be specified.
    /// If there is no mutation, you can use `EmptyMutation`.
    /// If there is no subscription, you can use `EmptySubscription`.
    pub fn build(
        query: Query,
        mutation: Mutation,
        subscription: Subscription,
    ) -> SchemaBuilder<Query, Mutation, Subscription> {
        let mut registry = Registry {
            types: Default::default(),
            directives: Default::default(),
            implements: Default::default(),
            query_type: Query::type_name().to_string(),
            mutation_type: if Mutation::is_empty() {
                None
            } else {
                Some(Mutation::type_name().to_string())
            },
            subscription_type: if Subscription::is_empty() {
                None
            } else {
                Some(Subscription::type_name().to_string())
            },
        };

        registry.add_directive(MetaDirective {
            name: "include",
            description: Some("Directs the executor to include this field or fragment only when the `if` argument is true."),
            locations: vec![
                __DirectiveLocation::FIELD,
                __DirectiveLocation::FRAGMENT_SPREAD,
                __DirectiveLocation::INLINE_FRAGMENT
            ],
            args: {
                let mut args = IndexMap::new();
                args.insert("if", MetaInputValue {
                    name: "if",
                    description: Some("Included when true."),
                    ty: "Boolean!".to_string(),
                    default_value: None,
                    validator: None,
                });
                args
            }
        });

        registry.add_directive(MetaDirective {
            name: "skip",
            description: Some("Directs the executor to skip this field or fragment when the `if` argument is true."),
            locations: vec![
                __DirectiveLocation::FIELD,
                __DirectiveLocation::FRAGMENT_SPREAD,
                __DirectiveLocation::INLINE_FRAGMENT
            ],
            args: {
                let mut args = IndexMap::new();
                args.insert("if", MetaInputValue {
                    name: "if",
                    description: Some("Skipped when true."),
                    ty: "Boolean!".to_string(),
                    default_value: None,
                    validator: None,
                });
                args
            }
        });

        registry.add_directive(MetaDirective {
            name: "defer",
            description: None,
            locations: vec![__DirectiveLocation::FIELD],
            args: Default::default(),
        });

        registry.add_directive(MetaDirective {
            name: "stream",
            description: None,
            locations: vec![__DirectiveLocation::FIELD],
            args: Default::default(),
        });

        // register scalars
        bool::create_type_info(&mut registry);
        i32::create_type_info(&mut registry);
        f32::create_type_info(&mut registry);
        String::create_type_info(&mut registry);
        ID::create_type_info(&mut registry);

        QueryRoot::<Query>::create_type_info(&mut registry);
        if !Mutation::is_empty() {
            Mutation::create_type_info(&mut registry);
        }
        if !Subscription::is_empty() {
            Subscription::create_type_info(&mut registry);
        }

        // federation
        registry.create_federation_types();

        SchemaBuilder {
            validation_mode: ValidationMode::Strict,
            query: QueryRoot {
                inner: query,
                disable_introspection: false,
            },
            mutation,
            subscription,
            registry,
            data: Default::default(),
            complexity: None,
            depth: None,
            extensions: Default::default(),
        }
    }

    /// Create a schema
    pub fn new(
        query: Query,
        mutation: Mutation,
        subscription: Subscription,
    ) -> Schema<Query, Mutation, Subscription> {
        Self::build(query, mutation, subscription).finish()
    }

    pub(crate) fn create_extensions(&self) -> Extensions {
        Extensions(
            self.extensions
                .iter()
                .map(|factory| factory())
                .collect_vec(),
        )
    }

    /// Execute query without create the `QueryBuilder`.
    pub async fn execute(&self, query_source: &str) -> Result<QueryResponse> {
        QueryBuilder::new(query_source).execute(self).await
    }

    /// Execute the query without create the `QueryBuilder`, returns a stream, the first result being the query result,
    /// followed by the incremental result. Only when there are `@defer` and `@stream` directives
    /// in the query will there be subsequent incremental results.
    pub async fn execute_stream(&self, query_source: &str) -> StreamResponse {
        QueryBuilder::new(query_source).execute_stream(self).await
    }

    pub(crate) fn prepare_query(
        &self,
        source: &str,
    ) -> Result<(Document, CacheControl, Extensions)> {
        // create extension instances
        let extensions = self.create_extensions();

        extensions.parse_start(source);
        let document = extensions.log_error(parse_query(source).map_err(Into::<Error>::into))?;
        extensions.parse_end(source, &document);

        // check rules
        extensions.validation_start();
        let CheckResult {
            cache_control,
            complexity,
            depth,
        } = extensions.log_error(check_rules(
            &self.env.registry,
            &document,
            self.validation_mode,
        ))?;
        extensions.validation_end();

        // check limit
        if let Some(limit_complexity) = self.complexity {
            if complexity > limit_complexity {
                return extensions
                    .log_error(Err(QueryError::TooComplex.into_error(Pos::default())));
            }
        }

        if let Some(limit_depth) = self.depth {
            if depth > limit_depth {
                return extensions.log_error(Err(QueryError::TooDeep.into_error(Pos::default())));
            }
        }

        Ok((document, cache_control, extensions))
    }

    /// Create subscription stream, typically called inside the `SubscriptionTransport::handle_request` method
    pub async fn create_subscription_stream(
        &self,
        source: &str,
        operation_name: Option<&str>,
        variables: Variables,
        ctx_data: Option<Arc<Data>>,
    ) -> Result<impl Stream<Item = Result<serde_json::Value>> + Send> {
        let (mut document, _, extensions) = self.prepare_query(source)?;

        if !document.retain_operation(operation_name) {
            return extensions.log_error(if let Some(name) = operation_name {
                Err(QueryError::UnknownOperationNamed {
                    name: name.to_string(),
                }
                .into_error(Pos::default()))
            } else {
                Err(QueryError::MissingOperation.into_error(Pos::default()))
            });
        }

        if document.current_operation().ty != OperationType::Subscription {
            return extensions.log_error(Err(QueryError::NotSupported.into_error(Pos::default())));
        }

        let resolve_id = AtomicUsize::default();
        let env = QueryEnv::new(
            extensions,
            variables,
            document,
            ctx_data.unwrap_or_default(),
        );
        let ctx = env.create_context(
            &self.env,
            None,
            &env.document.current_operation().selection_set,
            &resolve_id,
            None,
        );
        let mut streams = Vec::new();
        ctx.query_env
            .extensions
            .log_error(create_subscription_stream(self, env.clone(), &ctx, &mut streams).await)?;
        Ok(futures::stream::select_all(streams))
    }

    /// Create subscription connection, returns `Sink` and `Stream`.
    pub fn subscription_connection<T: SubscriptionTransport>(
        &self,
        transport: T,
    ) -> (
        mpsc::UnboundedSender<Bytes>,
        impl Stream<Item = Bytes> + Unpin,
    ) {
        create_connection(self.clone(), transport)
    }
}