// Mutation operations on the store
//
// CRUD (upsert, delete, modify), feedback tracking (mark_used, mark_wrong),
// maintenance (decay, fix_categories, cap_degree), and graph metrics.

use super::types::*;

use std::collections::{HashMap, HashSet};

impl Store {
    /// Add or update a node (appends to log + updates cache)
    pub fn upsert_node(&mut self, mut node: Node) -> Result<(), String> {
        if let Some(existing) = self.nodes.get(&node.key) {
            node.uuid = existing.uuid;
            node.version = existing.version + 1;
        }
        self.append_nodes(&[node.clone()])?;
        self.uuid_to_key.insert(node.uuid, node.key.clone());
        self.nodes.insert(node.key.clone(), node);
        Ok(())
    }

    /// Add a relation (appends to log + updates cache)
    pub fn add_relation(&mut self, rel: Relation) -> Result<(), String> {
        self.append_relations(std::slice::from_ref(&rel))?;
        self.relations.push(rel);
        Ok(())
    }

    /// Upsert a node: update if exists (and content changed), create if not.
    /// Returns: "created", "updated", or "unchanged".
    ///
    /// Provenance is determined by the POC_PROVENANCE env var if set,
    /// otherwise defaults to Manual.
    pub fn upsert(&mut self, key: &str, content: &str) -> Result<&'static str, String> {
        let prov = Provenance::from_env().unwrap_or(Provenance::Manual);
        self.upsert_provenance(key, content, prov)
    }

    /// Upsert with explicit provenance (for agent-created nodes).
    pub fn upsert_provenance(&mut self, key: &str, content: &str, provenance: Provenance) -> Result<&'static str, String> {
        if let Some(existing) = self.nodes.get(key) {
            if existing.content == content {
                return Ok("unchanged");
            }
            let mut node = existing.clone();
            node.content = content.to_string();
            node.provenance = provenance;
            node.version += 1;
            self.append_nodes(std::slice::from_ref(&node))?;
            self.nodes.insert(key.to_string(), node);
            Ok("updated")
        } else {
            let mut node = new_node(key, content);
            node.provenance = provenance;
            self.append_nodes(std::slice::from_ref(&node))?;
            self.uuid_to_key.insert(node.uuid, node.key.clone());
            self.nodes.insert(key.to_string(), node);
            Ok("created")
        }
    }

    /// Soft-delete a node (appends deleted version, removes from cache).
    pub fn delete_node(&mut self, key: &str) -> Result<(), String> {
        let node = self.nodes.get(key)
            .ok_or_else(|| format!("No node '{}'", key))?;
        let mut deleted = node.clone();
        deleted.deleted = true;
        deleted.version += 1;
        self.append_nodes(std::slice::from_ref(&deleted))?;
        self.nodes.remove(key);
        Ok(())
    }

    /// Rename a node: change its key, update debug strings on all edges.
    ///
    /// Graph edges (source/target UUIDs) are unaffected — they're already
    /// UUID-based. We update the human-readable source_key/target_key strings
    /// on relations, and created_at is preserved untouched.
    ///
    /// Appends: (new_key, v+1) + (old_key, deleted, v+1) + updated relations.
    pub fn rename_node(&mut self, old_key: &str, new_key: &str) -> Result<(), String> {
        if old_key == new_key {
            return Ok(());
        }
        if self.nodes.contains_key(new_key) {
            return Err(format!("Key '{}' already exists", new_key));
        }
        let node = self.nodes.get(old_key)
            .ok_or_else(|| format!("No node '{}'", old_key))?
            .clone();

        // New version under the new key
        let mut renamed = node.clone();
        renamed.key = new_key.to_string();
        renamed.version += 1;

        // Deletion record for the old key (same UUID, independent version counter)
        let mut tombstone = node.clone();
        tombstone.deleted = true;
        tombstone.version += 1;

        // Collect affected relations and update their debug key strings
        let updated_rels: Vec<_> = self.relations.iter()
            .filter(|r| r.source_key == old_key || r.target_key == old_key)
            .map(|r| {
                let mut r = r.clone();
                r.version += 1;
                if r.source_key == old_key { r.source_key = new_key.to_string(); }
                if r.target_key == old_key { r.target_key = new_key.to_string(); }
                r
            })
            .collect();

        // Persist (each append acquires its own file lock)
        self.append_nodes(&[renamed.clone(), tombstone])?;
        if !updated_rels.is_empty() {
            self.append_relations(&updated_rels)?;
        }

        // Update in-memory cache
        self.nodes.remove(old_key);
        self.uuid_to_key.insert(renamed.uuid, new_key.to_string());
        self.nodes.insert(new_key.to_string(), renamed);
        for updated in &updated_rels {
            if let Some(r) = self.relations.iter_mut().find(|r| r.uuid == updated.uuid) {
                r.source_key = updated.source_key.clone();
                r.target_key = updated.target_key.clone();
                r.version = updated.version;
            }
        }

        Ok(())
    }

    /// Modify a node in-place, bump version, and persist to capnp log.
    fn modify_node(&mut self, key: &str, f: impl FnOnce(&mut Node)) -> Result<(), String> {
        let node = self.nodes.get_mut(key)
            .ok_or_else(|| format!("No node '{}'", key))?;
        f(node);
        node.version += 1;
        let node = node.clone();
        self.append_nodes(&[node])
    }

    pub fn mark_used(&mut self, key: &str) {
        let boost = self.params.use_boost as f32;
        let _ = self.modify_node(key, |n| {
            n.uses += 1;
            n.weight = (n.weight + boost).min(1.0);
            if n.spaced_repetition_interval < 30 {
                n.spaced_repetition_interval = match n.spaced_repetition_interval {
                    1 => 3, 3 => 7, 7 => 14, 14 => 30, _ => 30,
                };
            }
            n.last_replayed = now_epoch();
        });
    }

    pub fn mark_wrong(&mut self, key: &str, _ctx: Option<&str>) {
        let _ = self.modify_node(key, |n| {
            n.wrongs += 1;
            n.weight = (n.weight - 0.1).max(0.0);
            n.spaced_repetition_interval = 1;
        });
    }

    pub fn record_gap(&mut self, desc: &str) {
        self.gaps.push(GapRecord {
            description: desc.to_string(),
            timestamp: today(),
        });
    }

    pub fn categorize(&mut self, key: &str, cat_str: &str) -> Result<(), String> {
        let cat = Category::from_str(cat_str)
            .ok_or_else(|| format!("Unknown category '{}'. Use: core/tech/gen/obs/task", cat_str))?;
        self.modify_node(key, |n| { n.category = cat; })
    }

    pub fn decay(&mut self) -> (usize, usize) {
        let base = self.params.decay_factor;
        let threshold = self.params.prune_threshold as f32;
        let mut decayed = 0;
        let mut pruned = 0;
        let mut updated = Vec::new();

        for (_key, node) in &mut self.nodes {
            let factor = node.category.decay_factor(base) as f32;
            let old_weight = node.weight;
            node.weight *= factor;

            // Clamp near-prune nodes instead of removing
            if node.weight < threshold {
                node.weight = node.weight.max(0.01);
                pruned += 1;
            }

            // Only persist nodes whose weight actually changed
            if (node.weight - old_weight).abs() > 1e-6 {
                node.version += 1;
                updated.push(node.clone());
                decayed += 1;
            }
        }

        if !updated.is_empty() {
            let _ = self.append_nodes(&updated);
        }

        (decayed, pruned)
    }

    /// Bulk recategorize nodes using rule-based logic.
    /// Returns (changed, unchanged) counts.
    pub fn fix_categories(&mut self) -> Result<(usize, usize), String> {
        let cfg = crate::config::get();
        let core_files: Vec<&str> = cfg.core_nodes.iter().map(|s| s.as_str()).collect();
        let tech_files = [
            "language-theory.md", "zoom-navigation.md",
            "rust-conversion.md", "poc-architecture.md",
        ];
        let tech_prefixes = ["design-"];
        let obs_files = [
            "reflections.md", "reflections-zoom.md", "differentiation.md",
            "cognitive-modes.md", "paper-notes.md", "inner-life.md",
            "conversation.md", "interests.md", "stuck-toolkit.md",
        ];
        let obs_prefixes = ["skill-", "worked-example-"];

        let mut changed_nodes = Vec::new();
        let mut unchanged = 0;

        let keys: Vec<String> = self.nodes.keys().cloned().collect();
        for key in &keys {
            let node = self.nodes.get(key).unwrap();
            if node.category != Category::Core {
                unchanged += 1;
                continue;
            }

            let file = key.split('#').next().unwrap_or(key);

            let new_cat = if core_files.iter().any(|&f| file == f) {
                None
            } else if tech_files.iter().any(|&f| file == f)
                || tech_prefixes.iter().any(|p| file.starts_with(p))
            {
                Some(Category::Technical)
            } else if obs_files.iter().any(|&f| file == f)
                || obs_prefixes.iter().any(|p| file.starts_with(p))
            {
                Some(Category::Observation)
            } else {
                Some(Category::General)
            };

            if let Some(cat) = new_cat {
                let node = self.nodes.get_mut(key).unwrap();
                node.category = cat;
                node.version += 1;
                changed_nodes.push(node.clone());
            } else {
                unchanged += 1;
            }
        }

        if !changed_nodes.is_empty() {
            self.append_nodes(&changed_nodes)?;
        }

        Ok((changed_nodes.len(), unchanged))
    }

    /// Cap node degree by soft-deleting edges from mega-hubs.
    pub fn cap_degree(&mut self, max_degree: usize) -> Result<(usize, usize), String> {
        let mut node_degree: HashMap<String, usize> = HashMap::new();
        for rel in &self.relations {
            if rel.deleted { continue; }
            *node_degree.entry(rel.source_key.clone()).or_default() += 1;
            *node_degree.entry(rel.target_key.clone()).or_default() += 1;
        }

        let mut node_edges: HashMap<String, Vec<usize>> = HashMap::new();
        for (i, rel) in self.relations.iter().enumerate() {
            if rel.deleted { continue; }
            node_edges.entry(rel.source_key.clone()).or_default().push(i);
            node_edges.entry(rel.target_key.clone()).or_default().push(i);
        }

        let mut to_delete: HashSet<usize> = HashSet::new();
        let mut hubs_capped = 0;

        for (_key, edge_indices) in &node_edges {
            let active: Vec<usize> = edge_indices.iter()
                .filter(|&&i| !to_delete.contains(&i))
                .copied()
                .collect();
            if active.len() <= max_degree { continue; }

            let mut auto_indices: Vec<(usize, f32)> = Vec::new();
            let mut link_indices: Vec<(usize, usize)> = Vec::new();
            for &i in &active {
                let rel = &self.relations[i];
                if rel.rel_type == RelationType::Auto {
                    auto_indices.push((i, rel.strength));
                } else {
                    let other = if &rel.source_key == _key {
                        &rel.target_key
                    } else {
                        &rel.source_key
                    };
                    let other_deg = node_degree.get(other).copied().unwrap_or(0);
                    link_indices.push((i, other_deg));
                }
            }

            let excess = active.len() - max_degree;

            auto_indices.sort_by(|a, b| a.1.total_cmp(&b.1));
            let auto_prune = excess.min(auto_indices.len());
            for &(i, _) in auto_indices.iter().take(auto_prune) {
                to_delete.insert(i);
            }

            let remaining_excess = excess.saturating_sub(auto_prune);
            if remaining_excess > 0 {
                link_indices.sort_by(|a, b| b.1.cmp(&a.1));
                let link_prune = remaining_excess.min(link_indices.len());
                for &(i, _) in link_indices.iter().take(link_prune) {
                    to_delete.insert(i);
                }
            }

            hubs_capped += 1;
        }

        let mut pruned_rels = Vec::new();
        for &i in &to_delete {
            self.relations[i].deleted = true;
            self.relations[i].version += 1;
            pruned_rels.push(self.relations[i].clone());
        }

        if !pruned_rels.is_empty() {
            self.append_relations(&pruned_rels)?;
        }

        self.relations.retain(|r| !r.deleted);

        Ok((hubs_capped, to_delete.len()))
    }

    pub fn category_counts(&self) -> HashMap<&str, usize> {
        let mut counts = HashMap::new();
        for node in self.nodes.values() {
            *counts.entry(node.category.label()).or_insert(0) += 1;
        }
        counts
    }

    /// Update graph-derived fields on all nodes
    pub fn update_graph_metrics(&mut self) {
        let g = self.build_graph();
        let communities = g.communities();

        for (key, node) in &mut self.nodes {
            node.community_id = communities.get(key).copied();
            node.clustering_coefficient = Some(g.clustering_coefficient(key));
            node.degree = Some(g.degree(key) as u32);
        }
    }
}