//! SurrealDB client and connection management
//!
//! Abstracts SurrealDB operations for the AI configuration assistant.
//! Supports both local and remote connections via HTTP.

use crate::storage::models::*;
use anyhow::Result;
use uuid::Uuid;

/// SurrealDB client for AI configuration assistant
///
/// Manages connections to SurrealDB (local or remote) with support for:
/// - Graph relationships between conversations, schemas, fields
/// - Full-text search on messages
/// - Reusable RAG results
/// - Schema validation with SurrealQL contracts
pub struct SurrealDbClient {
    /// Connection endpoint (e.g., "http://localhost:8000", "memory://", "file://./db.db")
    endpoint: String,
    /// SurrealDB namespace
    namespace: String,
    /// SurrealDB database name
    database: String,
}

impl SurrealDbClient {
    /// Create new SurrealDB client
    ///
    /// # Arguments
    /// * `endpoint` - Connection endpoint
    ///   - `"memory://"` - In-memory (development, data lost on restart)
    ///   - `"file://./typedialog.db"` - Local RocksDB file (development)
    ///   - `"http://localhost:8000"` - Local HTTP server
    ///   - `"https://surreal.example.com"` - Remote HTTP endpoint (production)
    /// * `namespace` - SurrealDB namespace (e.g., "default")
    /// * `database` - SurrealDB database name (e.g., "typedialog")
    ///
    /// # Errors
    /// Returns error if endpoint format is invalid
    pub async fn new(endpoint: &str, namespace: &str, database: &str) -> Result<Self> {
        // Validate endpoint
        let valid = endpoint == "memory://"
            || endpoint.starts_with("file://")
            || endpoint.starts_with("http");
        if !valid {
            return Err(anyhow::anyhow!(
                "Invalid endpoint. Use 'memory://', 'file://<path>', or 'http(s)://<host>:<port>'"
            ));
        }

        tracing::debug!(
            endpoint = %endpoint,
            namespace = %namespace,
            database = %database,
            "Creating SurrealDB client"
        );

        Ok(SurrealDbClient {
            endpoint: endpoint.to_string(),
            namespace: namespace.to_string(),
            database: database.to_string(),
        })
    }

    /// Get connection endpoint
    pub fn endpoint(&self) -> &str {
        &self.endpoint
    }

    /// Get namespace
    pub fn namespace(&self) -> &str {
        &self.namespace
    }

    /// Get database name
    pub fn database(&self) -> &str {
        &self.database
    }

    /// Initialize database schema
    ///
    /// Creates necessary tables, indexes, and relationships:
    /// - `conversations` - Main conversation records with status tracking
    /// - `messages` - Individual messages with optional RAG result links
    /// - `rag_results` - Reusable RAG retrieval results
    /// - `schemas` - Nickel schema definitions
    /// - `fields` - Extracted schema field metadata
    ///
    /// All tables include proper indexing:
    /// - Foreign key relationships for graph queries
    /// - Full-text search indexes on messages
    /// - Status and timestamp indexes for efficient filtering
    pub async fn initialize(&self) -> Result<()> {
        tracing::info!(
            endpoint = %self.endpoint,
            "Initializing SurrealDB schema (ns='{}', db='{}')",
            self.namespace,
            self.database
        );

        // TODO: Execute SurrealQL schema initialization via HTTP client
        // This would create:
        // - DEFINE TABLE conversations SCHEMAFULL;
        // - DEFINE TABLE messages SCHEMAFULL;
        // - DEFINE TABLE rag_results SCHEMAFULL;
        // - DEFINE TABLE schemas SCHEMAFULL;
        // - DEFINE TABLE fields SCHEMAFULL;
        // - DEFINE INDEX indexes for efficient queries

        Ok(())
    }

    // ============================================================================
    // CONVERSATION OPERATIONS
    // ============================================================================

    /// Create new conversation
    ///
    /// Initializes a new conversation for configuring a Nickel schema
    pub async fn create_conversation(&self, schema_id: &str) -> Result<String> {
        let id = Uuid::new_v4().to_string();
        tracing::debug!(conversation_id = %id, schema_id = %schema_id, "Creating conversation");

        // TODO: INSERT INTO conversations (id, schema_id, created_at, updated_at, status, collected_fields)
        // VALUES (:id, :schema_id, now(), now(), 'active', {})

        Ok(id)
    }

    /// Get conversation by ID
    pub async fn get_conversation(&self, _id: &str) -> Result<Option<Conversation>> {
        // TODO: SELECT * FROM conversations WHERE id = :id
        Ok(None)
    }

    /// List conversations with filters
    pub async fn list_conversations(
        &self,
        _filter: &ConversationFilter,
    ) -> Result<Vec<Conversation>> {
        // TODO: Build query with filters and execute
        Ok(vec![])
    }

    /// Update conversation status
    pub async fn update_conversation_status(
        &self,
        _id: &str,
        _status: ConversationStatus,
    ) -> Result<()> {
        // TODO: UPDATE conversations SET status = :status, updated_at = now() WHERE id = :id
        Ok(())
    }

    /// Update collected fields
    pub async fn update_collected_fields(
        &self,
        _id: &str,
        _fields: serde_json::Value,
    ) -> Result<()> {
        // TODO: UPDATE conversations SET collected_fields = :fields, updated_at = now() WHERE id = :id
        Ok(())
    }

    // ============================================================================
    // MESSAGE OPERATIONS
    // ============================================================================

    /// Create new message in conversation
    pub async fn create_message(
        &self,
        conversation_id: &str,
        role: MessageRole,
        _content: &str,
    ) -> Result<String> {
        let id = Uuid::new_v4().to_string();
        tracing::debug!(message_id = %id, conversation_id = %conversation_id, role = ?role, "Creating message");

        // TODO: INSERT INTO messages (id, conversation_id, role, content, timestamp, rag_result_ids)
        // VALUES (:id, :conversation_id, :role, :content, now(), [])

        Ok(id)
    }

    /// Get message by ID
    pub async fn get_message(&self, _id: &str) -> Result<Option<Message>> {
        // TODO: SELECT * FROM messages WHERE id = :id
        Ok(None)
    }

    /// List messages with filters
    pub async fn list_messages(&self, _filter: &MessageFilter) -> Result<Vec<Message>> {
        // TODO: Build query with filters, order by timestamp, apply limit/offset
        Ok(vec![])
    }

    /// Search messages with full-text search
    ///
    /// Uses SurrealDB full-text search to find messages containing specific terms
    pub async fn search_messages(
        &self,
        conversation_id: &str,
        query: &str,
    ) -> Result<Vec<Message>> {
        tracing::debug!(conversation_id = %conversation_id, query = %query, "Searching messages");

        // TODO: SELECT * FROM messages WHERE conversation_id = :conversation_id AND content CONTAINS :query
        Ok(vec![])
    }

    /// Link RAG results to message
    ///
    /// Associates RAG retrieval results with a message for relationship queries
    pub async fn link_rag_results(
        &self,
        _message_id: &str,
        _rag_result_ids: Vec<String>,
    ) -> Result<()> {
        // TODO: UPDATE messages SET rag_result_ids = :rag_result_ids WHERE id = :message_id
        Ok(())
    }

    // ============================================================================
    // RAG RESULT OPERATIONS
    // ============================================================================

    /// Create RAG retrieval result
    ///
    /// Stores reusable RAG results that can be linked to multiple messages
    pub async fn create_rag_result(
        &self,
        _doc_id: &str,
        _content: &str,
        _combined_score: f32,
        _semantic_score: f32,
        _keyword_score: f32,
    ) -> Result<String> {
        let id = Uuid::new_v4().to_string();

        // TODO: INSERT INTO rag_results (...) VALUES (...)
        Ok(id)
    }

    /// Get RAG result by ID
    pub async fn get_rag_result(&self, _id: &str) -> Result<Option<RagResult>> {
        // TODO: SELECT * FROM rag_results WHERE id = :id
        Ok(None)
    }

    // ============================================================================
    // SCHEMA OPERATIONS
    // ============================================================================

    /// Create schema record
    ///
    /// Stores Nickel schema for reuse across conversations
    pub async fn create_schema(&self, name: &str, _path: &str, _content: &str) -> Result<String> {
        let id = Uuid::new_v4().to_string();
        tracing::debug!(schema_id = %id, schema_name = %name, "Creating schema");

        // TODO: INSERT INTO schemas (id, name, path, content, created_at, updated_at) VALUES (...)
        Ok(id)
    }

    /// Get schema by ID
    pub async fn get_schema(&self, _id: &str) -> Result<Option<Schema>> {
        // TODO: SELECT * FROM schemas WHERE id = :id
        Ok(None)
    }

    /// Get schema by name
    pub async fn get_schema_by_name(&self, _name: &str) -> Result<Option<Schema>> {
        // TODO: SELECT * FROM schemas WHERE name = :name LIMIT 1
        Ok(None)
    }

    /// Get all schemas
    pub async fn list_schemas(&self) -> Result<Vec<Schema>> {
        // TODO: SELECT * FROM schemas ORDER BY created_at DESC
        Ok(vec![])
    }

    // ============================================================================
    // FIELD OPERATIONS
    // ============================================================================

    /// Create field definition
    ///
    /// Stores extracted field metadata from Nickel schema
    pub async fn create_field(
        &self,
        _schema_id: &str,
        _name: &str,
        _field_type: &str,
        _description: &str,
        _required: bool,
    ) -> Result<String> {
        let id = Uuid::new_v4().to_string();

        // TODO: INSERT INTO fields (id, schema_id, name, field_type, description, required, created_at)
        Ok(id)
    }

    /// Get fields for schema
    pub async fn get_schema_fields(&self, _schema_id: &str) -> Result<Vec<Field>> {
        // TODO: SELECT * FROM fields WHERE schema_id = :schema_id
        Ok(vec![])
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    #[tokio::test]
    async fn test_client_creation() {
        let client = SurrealDbClient::new("memory://", "default", "typedialog")
            .await
            .unwrap();
        assert_eq!(client.endpoint(), "memory://");
        assert_eq!(client.namespace(), "default");
        assert_eq!(client.database(), "typedialog");
    }

    #[tokio::test]
    async fn test_invalid_endpoint() {
        let result = SurrealDbClient::new("invalid://endpoint", "default", "typedialog").await;
        assert!(result.is_err());
    }

    #[tokio::test]
    async fn test_file_endpoint() {
        let client = SurrealDbClient::new("file://./test.db", "default", "typedialog")
            .await
            .unwrap();
        assert_eq!(client.endpoint(), "file://./test.db");
    }

    #[tokio::test]
    async fn test_http_endpoint() {
        let client = SurrealDbClient::new("http://localhost:8000", "default", "typedialog")
            .await
            .unwrap();
        assert_eq!(client.endpoint(), "http://localhost:8000");
    }

    #[tokio::test]
    async fn test_initialize() {
        let client = SurrealDbClient::new("memory://", "default", "typedialog")
            .await
            .unwrap();
        let result = client.initialize().await;
        assert!(result.is_ok());
    }

    #[tokio::test]
    async fn test_create_conversation() {
        let client = SurrealDbClient::new("memory://", "default", "typedialog")
            .await
            .unwrap();
        let result = client.create_conversation("schema1").await;
        assert!(result.is_ok());
        let id = result.unwrap();
        // ID should be a UUID
        assert!(!id.is_empty());
        assert_eq!(id.len(), 36); // UUID format: 8-4-4-4-12
    }

    #[tokio::test]
    async fn test_create_message() {
        let client = SurrealDbClient::new("memory://", "default", "typedialog")
            .await
            .unwrap();
        let result = client
            .create_message("conv1", MessageRole::User, "Hello")
            .await;
        assert!(result.is_ok());
    }

    #[tokio::test]
    async fn test_create_schema() {
        let client = SurrealDbClient::new("memory://", "default", "typedialog")
            .await
            .unwrap();
        let result = client.create_schema("config", "schema.ncl", "{}").await;
        assert!(result.is_ok());
    }
}
