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//! Extensions for schema

mod apollo_tracing;
mod logger;
mod tracing;

use crate::context::{QueryPathNode, ResolveId};
use crate::Result;

pub use self::apollo_tracing::ApolloTracing;
pub use self::logger::Logger;
pub use self::tracing::Tracing;
use crate::Error;
use serde_json::Value;

pub(crate) type BoxExtension = Box<dyn Extension>;

#[doc(hidden)]
pub struct Extensions(pub(crate) Vec<BoxExtension>);

/// Parameters for `Extension::resolve_field_start`
pub struct ResolveInfo<'a> {
    /// Because resolver is concurrent, `Extension::resolve_field_start` and `Extension::resolve_field_end` are
    /// not strictly ordered, so each pair is identified by an id.
    pub resolve_id: ResolveId,

    /// Current path node, You can go through the entire path.
    pub path_node: &'a QueryPathNode<'a>,

    /// Parent type
    pub parent_type: &'a str,

    /// Current return type, is qualified name.
    pub return_type: &'a str,
}

/// Represents a GraphQL extension
#[allow(unused_variables)]
pub trait Extension: Sync + Send + 'static {
    /// If this extension needs to output data to query results, you need to specify a name.
    fn name(&self) -> Option<&'static str> {
        None
    }

    /// Called at the begin of the parse.
    fn parse_start(&self, query_source: &str) {}

    /// Called at the end of the parse.
    fn parse_end(&self) {}

    /// Called at the begin of the validation.
    fn validation_start(&self) {}

    /// Called at the end of the validation.
    fn validation_end(&self) {}

    /// Called at the begin of the execution.
    fn execution_start(&self) {}

    /// Called at the end of the execution.
    fn execution_end(&self) {}

    /// Called at the begin of the resolve field.
    fn resolve_start(&self, info: &ResolveInfo<'_>) {}

    /// Called at the end of the resolve field.
    fn resolve_end(&self, info: &ResolveInfo<'_>) {}

    /// Called when an error occurs.
    fn error(&self, err: &Error) {}

    /// Get the results
    fn result(&self) -> Option<serde_json::Value> {
        None
    }
}

impl Extensions {
    pub(crate) fn log_error<T>(&self, res: Result<T>) -> Result<T> {
        if let Err(err) = &res {
            self.error(err);
        }
        res
    }
}

impl Extension for Extensions {
    fn parse_start(&self, query_source: &str) {
        self.0.iter().for_each(|e| e.parse_start(query_source));
    }

    fn parse_end(&self) {
        self.0.iter().for_each(|e| e.parse_end());
    }

    fn validation_start(&self) {
        self.0.iter().for_each(|e| e.validation_start());
    }

    fn validation_end(&self) {
        self.0.iter().for_each(|e| e.validation_end());
    }

    fn execution_start(&self) {
        self.0.iter().for_each(|e| e.execution_start());
    }

    fn execution_end(&self) {
        self.0.iter().for_each(|e| e.execution_end());
    }

    fn resolve_start(&self, info: &ResolveInfo<'_>) {
        self.0.iter().for_each(|e| e.resolve_start(info));
    }

    fn resolve_end(&self, resolve_id: &ResolveInfo<'_>) {
        self.0.iter().for_each(|e| e.resolve_end(resolve_id));
    }

    fn error(&self, err: &Error) {
        self.0.iter().for_each(|e| e.error(err));
    }

    fn result(&self) -> Option<Value> {
        if !self.0.is_empty() {
            let value = self
                .0
                .iter()
                .filter_map(|e| {
                    if let Some(name) = e.name() {
                        e.result().map(|res| (name.to_string(), res))
                    } else {
                        None
                    }
                })
                .collect::<serde_json::Map<_, _>>();
            if value.is_empty() {
                None
            } else {
                Some(value.into())
            }
        } else {
            None
        }
    }
}