bevy_persistence_database 0.2.10

use crate::bevy::components::Guid;
use crate::core::db::read_version;
use crate::core::query::{FilterExpression, PaginationConfig, PersistenceQuerySpecification};
use crate::core::session::PersistenceSession;
use crate::core::versioning::version_manager::VersionKey;
use super::cache::CachePolicy;
use super::persistence_query_system_param::PersistentQuery;
use super::query_thread_local::take_pagination_config;
use bevy::ecs::query::{QueryData, QueryFilter};
use bevy::prelude::{Entity, Mut, World};
use rayon::prelude::*;
use std::hash::{Hash, Hasher};

impl<'w, 's, Q: QueryData + 'static, F: QueryFilter + 'static> PersistentQuery<'w, 's, Q, F> {
    #[inline]
    pub(crate) fn apply_one_document(
        world: &mut World,
        session: &mut PersistenceSession,
        doc: &serde_json::Value,
        comps: &[&'static str],
        allow_overwrite: bool,
        key_field: &str,
    ) {
        let Some(key) = doc
            .get(key_field)
            .and_then(|v| v.as_str())
            .map(|s| s.to_string())
        else {
            bevy::log::trace!(
                "apply_one_document: skipping doc missing key '{}'",
                key_field
            );
            return;
        };
        let version = read_version(doc).unwrap_or(1);

        // Try to find an existing entity by Guid first.
        let existing_entity = world
            .query::<(Entity, &Guid)>()
            .iter(world)
            .find(|(_, g)| g.id() == key)
            .map(|(e, _)| e);

        // Resolve or spawn the entity for this key
        let (entity, existed) = if let Some(existing) = existing_entity {
            if !session.entity_keys().contains_key(&existing) {
                session.insert_entity_key(existing, key.clone());
            }
            (existing, true)
        } else if let Some((candidate, _)) = session
            .entity_keys()
            .iter()
            .find(|(_, k)| **k == key)
            .map(|(e, k)| (*e, k.clone()))
        {
            if world.get_entity(candidate).is_ok() {
                (candidate, true)
            } else {
                let e = world.spawn(Guid::new(key.clone())).id();
                session.insert_entity_key(e, key.clone());
                (e, false)
            }
        } else {
            let e = world.spawn(Guid::new(key.clone())).id();
            session.insert_entity_key(e, key.clone());
            (e, false)
        };

        if existed && !allow_overwrite {
            bevy::log::trace!(
                "apply_one_document: skip overwrite entity={:?} key={}",
                entity,
                key
            );
            return;
        }

        // Cache/refresh version
        session
            .version_manager_mut()
            .set_version(VersionKey::Entity(key.clone()), version);

        // Insert components - optimized for common case
        if !comps.is_empty() {
            for &comp_name in comps {
                if let Some(val) = doc.get(comp_name) {
                    if let Some(deser) = session.component_deserializer(comp_name) {
                        if let Err(e) = deser(world, entity, val.clone()) {
                            bevy::log::error!(
                                "Failed to deserialize component {}: {}",
                                comp_name,
                                e
                            );
                        }
                    }
                }
            }
        } else {
            for (registered_name, deser) in session.component_deserializers() {
                if let Some(val) = doc.get(registered_name) {
                    if let Err(e) = deser(world, entity, val.clone()) {
                        bevy::log::error!(
                            "Failed to deserialize component {}: {}",
                            registered_name,
                            e
                        );
                    }
                }
            }
        }
    }

    pub(crate) fn process_documents(
        &mut self,
        documents: Vec<serde_json::Value>,
        comp_names: &[&'static str],
        allow_overwrite: bool,
    ) {
        let key_field = self.db.connection.document_key_field();
        let explicit_components = comp_names.to_vec();
        bevy::log::trace!(
            "PQ::process_documents: deferring {} docs; comps={:?}; allow_overwrite={}",
            documents.len(),
            explicit_components,
            allow_overwrite
        );

        // For large document sets, use parallel processing with chunks
        if documents.len() > 1000 {
            // Process documents in parallel chunks
            const CHUNK_SIZE: usize = 250;
            let chunks: Vec<Vec<serde_json::Value>> = documents
                .chunks(CHUNK_SIZE)
                .map(|chunk| chunk.to_vec())
                .collect();

            chunks.into_par_iter().for_each(|chunk| {
                // Create a single operation that processes a chunk of documents
                let comps = explicit_components.clone();
                let allow = allow_overwrite;
                let key_field = key_field.to_string();

                self.ops.push(Box::new(move |world: &mut World| {
                    bevy::log::trace!(
                        "PQ::process_documents/op: applying deferred chunk of {} documents",
                        chunk.len()
                    );
                    world.resource_scope(|world, mut session: Mut<PersistenceSession>| {
                        for doc in &chunk {
                            Self::apply_one_document(
                                world,
                                &mut session,
                                doc,
                                &comps,
                                allow,
                                &key_field,
                            );
                        }
                    });
                }));
            });
        } else {
            // Batch the entire small set in a single scope to avoid per-doc locking
            let docs = documents;
            let comps = explicit_components.clone();
            let allow = allow_overwrite;
            let key_field = key_field.to_string();

            self.ops.push(Box::new(move |world: &mut World| {
                bevy::log::trace!(
                    "PQ::process_documents/op: applying deferred batch of {} documents",
                    docs.len()
                );
                world.resource_scope(|world, mut session: Mut<PersistenceSession>| {
                    for doc in &docs {
                        Self::apply_one_document(
                            world,
                            &mut session,
                            doc,
                            &comps,
                            allow,
                            &key_field,
                        );
                    }
                });
            }));
        }
    }

    pub(crate) fn execute_combined_load(
        &mut self,
        cache_policy: CachePolicy,
        presence_with: Vec<&'static str>,
        presence_without: Vec<&'static str>,
        fetch_only: Vec<&'static str>,
        value_filters: Option<FilterExpression>,
        hash_salts: &[&'static str],
        force_full_docs: bool,
        store: String,
    ) {
        if store.is_empty() {
            bevy::log::error!("PQ::execute_combined_load: store is required");
            return;
        }
        // Compute cache hash
        let mut hasher = std::collections::hash_map::DefaultHasher::new();
        std::any::type_name::<Q>().hash(&mut hasher);
        for &salt in hash_salts {
            salt.hash(&mut hasher);
        }
        for &name in &presence_with {
            name.hash(&mut hasher);
        }
        for &name in &presence_without {
            name.hash(&mut hasher);
        }
        for &name in &fetch_only {
            name.hash(&mut hasher);
        }
        if let Some(expr) = &value_filters {
            format!("{:?}", expr).hash(&mut hasher);
        }
        let query_hash = hasher.finish();

        bevy::log::debug!(
            "PQ::execute_combined_load enter: type={} hash={:#x} cache_policy={:?} salts={:?}",
            std::any::type_name::<Q>(),
            query_hash,
            cache_policy,
            hash_salts
        );

        let should_query_db = match cache_policy {
            CachePolicy::ForceRefresh => true,
            CachePolicy::UseCache => !self.cache.contains(query_hash),
        };

        bevy::log::debug!(
            "PQ::execute_combined_load: should_query_db={} presence_with={:?} presence_without={:?} fetch_only={:?} expr={:?}",
            should_query_db,
            presence_with,
            presence_without,
            fetch_only,
            value_filters
        );

        if should_query_db {
            let spec = PersistenceQuerySpecification {
                store: store.clone(),
                kind: crate::core::db::connection::DocumentKind::Entity,
                presence_with: presence_with.clone(),
                presence_without: presence_without.clone(),
                fetch_only: fetch_only.clone(),
                value_filters: value_filters.clone(),
                return_full_docs: force_full_docs
                    || (presence_with.is_empty() && presence_without.is_empty()),
                pagination: take_pagination_config(),
            };

            // Check if pagination is active
            if let Some(page_size) = spec.pagination.as_ref().map(|p| p.page_size) {
                // Determine allow_overwrite based on cache policy or presence filters
                let allow_overwrite =
                    matches!(cache_policy, CachePolicy::ForceRefresh) || !presence_with.is_empty();
                self.process_paginated_load(&spec, page_size, allow_overwrite);
            } else {
                // Original single-load code
                match self
                    .runtime
                    .block_on(self.db.connection.execute_documents(&spec))
                {
                    Ok(documents) => {
                        bevy::log::debug!(
                            "PQ::execute_combined_load: backend returned {} documents; immediate_world_ptr={} ",
                            documents.len(),
                            self.world_ptr.is_some()
                        );
                        let allow_overwrite = matches!(cache_policy, CachePolicy::ForceRefresh)
                            || !presence_with.is_empty();

                        let comps_to_deser: Vec<&'static str> =
                            if presence_with.is_empty() && presence_without.is_empty() {
                                Vec::new()
                            } else {
                                fetch_only.clone()
                            };

                        if let Some(ptr_res) = &self.world_ptr {
                            let world: &mut World = ptr_res.as_world_mut();

                            let key_field = self.db.connection.document_key_field();
                            // Apply all documents in a single scope to minimize world locking overhead.
                            world.resource_scope(|world, mut session: Mut<PersistenceSession>| {
                                for doc in &documents {
                                    Self::apply_one_document(
                                        world,
                                        &mut session,
                                        doc,
                                        &comps_to_deser,
                                        allow_overwrite,
                                        key_field,
                                    );
                                }

                                // Fetch resources once alongside the entity loads.
                                let rt = world
                                    .resource::<crate::bevy::plugins::persistence_plugin::TokioRuntime>()
                                    .runtime
                                    .clone();
                                let db = self.db.connection.clone();
                                bevy::log::trace!("PQ::immediate_apply: fetching resources");
                                rt.block_on(
                                    session.fetch_and_insert_resources(&*db, &store, world),
                                )
                                .ok();
                            });

                            bevy::log::trace!("PQ::immediate_apply: world.flush()");
                            world.flush();

                            // Note: inner query (self.query) has a stale view of the world
                            // Pass-through methods like get_many() use fresh world queries instead

                            // Compare what the inner Query vs a fresh QueryState sees after immediate apply.
                            let inner_cnt = self.query.iter().count();
                            bevy::log::trace!(
                                "PQ::immediate_apply: inner_query_iter_count={}",
                                inner_cnt
                            );

                            // Warm-up current archetypes count for diagnostics via fresh QueryState
                            let lhs_cnt = {
                                let mut qs: bevy::ecs::query::QueryState<(Entity, Q), F> =
                                    bevy::ecs::query::QueryState::new(world);
                                qs.iter(&*world).count()
                            };
                            bevy::log::trace!(
                                "PQ::immediate_apply: fresh_qstate_iter_count={}",
                                lhs_cnt
                            );
                        } else {
                            bevy::log::trace!(
                                "PQ::execute_combined_load: deferring {} docs",
                                documents.len()
                            );
                            self.process_documents(documents, &comps_to_deser, allow_overwrite);

                            // Also fetch resources alongside any query (deferred)
                            let db = self.db.connection.clone();
                            self.ops.push(Box::new(move |world: &mut World| {
                                world.resource_scope(|world, mut session: Mut<PersistenceSession>| {
                                    let rt = world
                                        .resource::<crate::bevy::plugins::persistence_plugin::TokioRuntime>()
                                        .runtime
                                        .clone();
                                    bevy::log::trace!("PQ::execute_combined_load: fetching resources");
                                    // Use db directly rather than dereferencing it
                                    rt.block_on(session.fetch_and_insert_resources(&*db, &store, world)).ok();
                                });
                            }));
                        }
                    }
                    Err(e) => {
                        bevy::log::error!("Error fetching documents: {}", e);
                        return;
                    }
                }
            }

            // Cache the query hash if successful
            if !matches!(cache_policy, CachePolicy::ForceRefresh) {
                bevy::log::trace!("PQ::execute_combined_load: caching hash {:#x}", query_hash);
                self.cache.insert(query_hash);
            }
        } else {
            bevy::log::trace!(
                "Skipping DB query - using cached results for hash={:#x}",
                query_hash
            );
        }
    }

    fn process_paginated_load(
        &mut self,
        spec: &PersistenceQuerySpecification,
        page_size: usize,
        allow_overwrite: bool,
    ) {
        bevy::log::debug!("Processing paginated load with page_size={}", page_size);

        // First get total count
        let total = match self
            .runtime
            .block_on(self.db.connection.count_documents(spec))
        {
            Ok(count) => count,
            Err(e) => {
                bevy::log::error!("Error counting documents: {}", e);
                return;
            }
        };

        let pages = (total + page_size - 1) / page_size; // Ceiling division
        bevy::log::debug!("Paginated load: total={} pages={}", total, pages);

        // Process each page
        let mut processed = 0;
        for page in 0..pages {
            let mut page_spec = spec.clone();
            page_spec.pagination = Some(PaginationConfig {
                page_size,
                page_number: page,
            });

            match self
                .runtime
                .block_on(self.db.connection.execute_documents(&page_spec))
            {
                Ok(documents) => {
                    processed += documents.len();
                    bevy::log::debug!(
                        "Loaded page {}/{} with {} documents (total processed: {}/{})",
                        page + 1,
                        pages,
                        documents.len(),
                        processed,
                        total
                    );

                    let comps_to_deser =
                        if spec.presence_with.is_empty() && spec.presence_without.is_empty() {
                            Vec::new()
                        } else {
                            spec.fetch_only.clone()
                        };

                    self.process_documents(documents, &comps_to_deser, allow_overwrite);
                }
                Err(e) => {
                    bevy::log::error!("Error fetching documents page {}: {}", page, e);
                    break;
                }
            }
        }
    }
}