pub mod edge;
pub mod r#enum;
pub mod executors;
pub mod formats;
pub mod page;
pub mod punc;
pub mod object;
pub mod relation;
pub mod schema;
pub mod r#type;

// External mock exports inside the executor sub-folder

use r#enum::Enum;
use executors::DatabaseExecutor;

#[cfg(not(test))]
use executors::pgrx::SpiExecutor;

#[cfg(test)]
use executors::mock::MockExecutor;

use punc::Punc;
use relation::Relation;
use schema::Schema;
use serde_json::Value;
use std::collections::HashMap;
use std::sync::Arc;
use r#type::Type;

pub struct Database {
  pub enums: HashMap<String, Enum>,
  pub types: HashMap<String, Type>,
  pub puncs: HashMap<String, Punc>,
  pub relations: HashMap<String, Relation>,
  pub schemas: HashMap<String, Arc<Schema>>,
  pub executor: Box<dyn DatabaseExecutor + Send + Sync>,
}

impl Database {
  pub fn new(val: &serde_json::Value) -> (Self, crate::drop::Drop) {
    let mut db = Self {
      enums: HashMap::new(),
      types: HashMap::new(),
      relations: HashMap::new(),
      puncs: HashMap::new(),
      schemas: HashMap::new(),
      #[cfg(not(test))]
      executor: Box::new(SpiExecutor::new()),
      #[cfg(test)]
      executor: Box::new(MockExecutor::new()),
    };

    let mut errors = Vec::new();

    if let Some(arr) = val.get("enums").and_then(|v| v.as_array()) {
      for item in arr {
        match serde_json::from_value::<Enum>(item.clone()) {
          Ok(def) => {
            db.enums.insert(def.name.clone(), def);
          }
          Err(e) => {
            errors.push(crate::drop::Error {
              code: "DATABASE_ENUM_PARSE_FAILED".to_string(),
              message: format!("Failed to parse database enum: {}", e),
              details: crate::drop::ErrorDetails::default(),
            });
          }
        }
      }
    }

    if let Some(arr) = val.get("types").and_then(|v| v.as_array()) {
      for item in arr {
        match serde_json::from_value::<Type>(item.clone()) {
          Ok(def) => {
            db.types.insert(def.name.clone(), def);
          }
          Err(e) => {
            errors.push(crate::drop::Error {
              code: "DATABASE_TYPE_PARSE_FAILED".to_string(),
              message: format!("Failed to parse database type: {}", e),
              details: crate::drop::ErrorDetails::default(),
            });
          }
        }
      }
    }

    if let Some(arr) = val.get("relations").and_then(|v| v.as_array()) {
      for item in arr {
        match serde_json::from_value::<Relation>(item.clone()) {
          Ok(def) => {
            if db.types.contains_key(&def.source_type)
              && db.types.contains_key(&def.destination_type)
            {
              db.relations.insert(def.constraint.clone(), def);
            }
          }
          Err(e) => {
            errors.push(crate::drop::Error {
              code: "DATABASE_RELATION_PARSE_FAILED".to_string(),
              message: format!("Failed to parse database relation: {}", e),
              details: crate::drop::ErrorDetails::default(),
            });
          }
        }
      }
    }

    if let Some(arr) = val.get("puncs").and_then(|v| v.as_array()) {
      for item in arr {
        match serde_json::from_value::<Punc>(item.clone()) {
          Ok(def) => {
            db.puncs.insert(def.name.clone(), def);
          }
          Err(e) => {
            errors.push(crate::drop::Error {
              code: "DATABASE_PUNC_PARSE_FAILED".to_string(),
              message: format!("Failed to parse database punc: {}", e),
              details: crate::drop::ErrorDetails::default(),
            });
          }
        }
      }
    }

    if let Some(arr) = val.get("schemas").and_then(|v| v.as_array()) {
      for (i, item) in arr.iter().enumerate() {
        match serde_json::from_value::<Schema>(item.clone()) {
          Ok(mut schema) => {
            let id = schema
              .obj
              .id
              .clone()
              .unwrap_or_else(|| format!("schema_{}", i));
            schema.obj.id = Some(id.clone());
            db.schemas.insert(id, Arc::new(schema));
          }
          Err(e) => {
            errors.push(crate::drop::Error {
              code: "DATABASE_SCHEMA_PARSE_FAILED".to_string(),
              message: format!("Failed to parse database schema: {}", e),
              details: crate::drop::ErrorDetails::default(),
            });
          }
        }
      }
    }

    db.compile(&mut errors);
    let drop = if errors.is_empty() {
      crate::drop::Drop::success()
    } else {
      crate::drop::Drop::with_errors(errors)
    };
    (db, drop)
  }

  /// Override the default executor for unit testing
  pub fn with_executor(mut self, executor: Box<dyn DatabaseExecutor + Send + Sync>) -> Self {
    self.executor = executor;
    self
  }

  /// Executes a query expecting a single JSONB array return, representing rows.
  pub fn query(&self, sql: &str, args: Option<Vec<Value>>) -> Result<Value, String> {
    self.executor.query(sql, args)
  }

  /// Executes an operation (INSERT, UPDATE, DELETE, or pg_notify) that does not return rows.
  pub fn execute(&self, sql: &str, args: Option<Vec<Value>>) -> Result<(), String> {
    self.executor.execute(sql, args)
  }

  /// Returns the current authenticated user's ID
  pub fn auth_user_id(&self) -> Result<String, String> {
    self.executor.auth_user_id()
  }

  /// Returns the current transaction timestamp
  pub fn timestamp(&self) -> Result<String, String> {
    self.executor.timestamp()
  }

  pub fn compile(&mut self, errors: &mut Vec<crate::drop::Error>) {
    let mut harvested = Vec::new();
    for schema_arc in self.schemas.values_mut() {
        if let Some(s) = std::sync::Arc::get_mut(schema_arc) {
          s.collect_schemas(None, &mut harvested, errors);
        }
    }
    for (id, schema) in harvested {
      self.schemas.insert(id, Arc::new(schema));
    }

    self.collect_schemas(errors);

    // Mathematically evaluate all property inheritances, formats, schemas, and foreign key edges topographically over OnceLocks
    let mut visited = std::collections::HashSet::new();
    for schema_arc in self.schemas.values() {
      schema_arc.as_ref().compile(self, &mut visited, errors);
    }
  }

  fn collect_schemas(&mut self, errors: &mut Vec<crate::drop::Error>) {
    let mut to_insert = Vec::new();

    // Pass 1: Extract all Schemas structurally off top level definitions into the master registry.
    // Validate every node recursively via string filters natively!
    for type_def in self.types.values() {
      for mut schema in type_def.schemas.clone() {
        schema.collect_schemas(None, &mut to_insert, errors);
      }
    }
    for punc_def in self.puncs.values() {
      for mut schema in punc_def.schemas.clone() {
        schema.collect_schemas(None, &mut to_insert, errors);
      }
    }
    for enum_def in self.enums.values() {
      for mut schema in enum_def.schemas.clone() {
        schema.collect_schemas(None, &mut to_insert, errors);
      }
    }

    for (id, schema) in to_insert {
      self.schemas.insert(id, Arc::new(schema));
    }
  }

  /// Inspects the Postgres pg_constraint relations catalog to securely identify
  /// the precise Foreign Key connecting a parent and child hierarchy path.
  pub fn resolve_relation<'a>(
    &'a self,
    parent_type: &str,
    child_type: &str,
    prop_name: &str,
    relative_keys: Option<&Vec<String>>,
    is_array: bool,
    schema_id: Option<&str>,
    path: &str,
    errors: &mut Vec<crate::drop::Error>,
  ) -> Option<(&'a crate::database::relation::Relation, bool)> {
    // Enforce graph locality by ensuring we don't accidentally crawl to pure structural entity boundaries
    if parent_type == "entity" && child_type == "entity" {
      return None;
    }

    let p_def = self.types.get(parent_type)?;
    let c_def = self.types.get(child_type)?;

    let mut matching_rels = Vec::new();
    let mut directions = Vec::new();

    // Scour the complete catalog for any Edge matching the inheritance scope of the two objects
    // This automatically binds polymorphic structures (e.g. recognizing a relationship targeting User
    // also natively binds instances specifically typed as Person).
    let mut all_rels: Vec<&crate::database::relation::Relation> = self.relations.values().collect();
    all_rels.sort_by(|a, b| a.constraint.cmp(&b.constraint));

    for rel in all_rels {
      let mut is_forward =
        p_def.hierarchy.contains(&rel.source_type) && c_def.hierarchy.contains(&rel.destination_type);
      let is_reverse =
        p_def.hierarchy.contains(&rel.destination_type) && c_def.hierarchy.contains(&rel.source_type);

      // Structural Cardinality Filtration:
      // If the schema requires a collection (Array), it is mathematically impossible for a pure
      // Forward scalar edge (where the parent holds exactly one UUID pointer) to fulfill a One-to-Many request.
      // Thus, if it's an array, we fully reject pure Forward edges and only accept Reverse edges (or Junction edges).
      if is_array && is_forward && !is_reverse {
        is_forward = false;
      }

      if is_forward {
        matching_rels.push(rel);
        directions.push(true);
      } else if is_reverse {
        matching_rels.push(rel);
        directions.push(false);
      }
    }

    // Abort relation discovery early if no hierarchical inheritance match was found
    if matching_rels.is_empty() {
      let mut details = crate::drop::ErrorDetails {
        path: path.to_string(),
        ..Default::default()
      };
      if let Some(sid) = schema_id {
        details.schema = Some(sid.to_string());
      }

      errors.push(crate::drop::Error {
        code: "EDGE_MISSING".to_string(),
        message: format!(
          "No database relation exists between '{}' and '{}' for property '{}'",
          parent_type, child_type, prop_name
        ),
        details,
      });
      return None;
    }

    // Ideal State: The objects only share a solitary structural relation, resolving ambiguity instantly.
    if matching_rels.len() == 1 {
      return Some((matching_rels[0], directions[0]));
    }

    let mut chosen_idx = 0;
    let mut resolved = false;

    // Exact Prefix Disambiguation: Determine if the database specifically names this constraint
    // directly mapping to the JSON Schema property name (e.g., `fk_{child}_{property_name}`)
    for (i, rel) in matching_rels.iter().enumerate() {
      if let Some(prefix) = &rel.prefix {
        if prop_name.starts_with(prefix)
          || prefix.starts_with(prop_name)
          || prefix.replace("_", "") == prop_name.replace("_", "")
        {
          chosen_idx = i;
          resolved = true;
          break;
        }
      }
    }

    // Complex Subgraph Resolution: The database contains multiple equally explicit foreign key constraints
    // linking these objects (such as pointing to `source` and `target` in Many-to-Many junction models).
    if !resolved && relative_keys.is_some() {
      // Twin Deduction Pass 1: We inspect the exact properties structurally defined inside the compiled payload
      // to observe which explicit relation arrow the child payload natively consumes.
      let keys = relative_keys.unwrap();
      let mut consumed_rel_idx = None;
      for (i, rel) in matching_rels.iter().enumerate() {
        if let Some(prefix) = &rel.prefix {
          if keys.contains(prefix) {
            consumed_rel_idx = Some(i);
            break; // Found the routing edge explicitly consumed by the schema payload
          }
        }
      }

      // Twin Deduction Pass 2: Knowing which arrow points outbound, we can mathematically deduce its twin
      // providing the reverse ownership on the same junction boundary must be the incoming Edge to the parent.
      if let Some(used_idx) = consumed_rel_idx {
        let used_rel = matching_rels[used_idx];
        let mut twin_ids = Vec::new();
        for (i, rel) in matching_rels.iter().enumerate() {
          if i != used_idx
            && rel.source_type == used_rel.source_type
            && rel.destination_type == used_rel.destination_type
            && rel.prefix.is_some()
          {
            twin_ids.push(i);
          }
        }

        if twin_ids.len() == 1 {
          chosen_idx = twin_ids[0];
          resolved = true;
        }
      }
    }

    // Implicit Base Fallback: If no complex explicit paths resolve, but exactly one relation
    // sits entirely naked (without a constraint prefix), it must be the core structural parent ownership.
    if !resolved {
      let mut null_prefix_ids = Vec::new();
      for (i, rel) in matching_rels.iter().enumerate() {
        if rel.prefix.is_none() {
          null_prefix_ids.push(i);
        }
      }
      if null_prefix_ids.len() == 1 {
        chosen_idx = null_prefix_ids[0];
        resolved = true;
      }
    }

    // If we exhausted all mathematical deduction pathways and STILL cannot isolate a single edge,
    // we must abort rather than silently guessing. Returning None prevents arbitrary SQL generation
    // and forces a clean structural error for the architect.
    if !resolved {
      let mut details = crate::drop::ErrorDetails {
        path: path.to_string(),
        context: serde_json::to_value(&matching_rels).ok(),
        cause: Some("Multiple conflicting constraints found matching prefixes".to_string()),
        ..Default::default()
      };
      if let Some(sid) = schema_id {
        details.schema = Some(sid.to_string());
      }

      errors.push(crate::drop::Error {
        code: "AMBIGUOUS_TYPE_RELATIONS".to_string(),
        message: format!(
          "Ambiguous database relation between '{}' and '{}' for property '{}'",
          parent_type, child_type, prop_name
        ),
        details,
      });
      return None;
    }

    Some((matching_rels[chosen_idx], directions[chosen_idx]))
  }
}