//! Unified File Format and I/O Trait System for PandRS
//!
//! This module provides a comprehensive trait-based system for handling
//! various data formats, I/O operations, and data transformation pipelines
//! in a unified and extensible manner.

use crate::core::error::{Error, Result};
use crate::dataframe::DataFrame;
use std::collections::HashMap;
use std::future::Future;
use std::io::{Read, Write};
use std::path::Path;
use std::pin::Pin;
use std::sync::Arc;

/// Unified trait for all file format operations
pub trait FileFormat: Send + Sync {
    /// Format identifier
    fn format_name(&self) -> &'static str;

    /// Supported file extensions
    fn file_extensions(&self) -> Vec<&'static str>;

    /// MIME types supported
    fn mime_types(&self) -> Vec<&'static str>;

    /// Check if the format can handle the given file
    fn can_handle_file(&self, path: &Path) -> bool;

    /// Check if the format can handle the given data
    fn can_handle_data(&self, data: &[u8]) -> bool;

    /// Read DataFrame from a file path with generic options
    fn read_from_path_with_options(
        &self,
        path: &Path,
        options: &HashMap<String, String>,
    ) -> Result<DataFrame>;

    /// Read DataFrame from bytes with generic options
    fn read_from_bytes_with_options(
        &self,
        data: &[u8],
        options: &HashMap<String, String>,
    ) -> Result<DataFrame>;

    /// Write DataFrame to a file path with generic options
    fn write_to_path_with_options(
        &self,
        df: &DataFrame,
        path: &Path,
        options: &HashMap<String, String>,
    ) -> Result<()>;

    /// Write DataFrame to bytes with generic options
    fn write_to_bytes_with_options(
        &self,
        df: &DataFrame,
        options: &HashMap<String, String>,
    ) -> Result<Vec<u8>>;

    /// Get format metadata from file
    fn get_metadata(&self, path: &Path) -> Result<HashMap<String, String>>;

    /// Validate format-specific options
    fn validate_options(&self, options: &HashMap<String, String>) -> Result<()>;

    /// Get default options
    fn default_options(&self) -> HashMap<String, String>;

    /// Get format capabilities
    fn capabilities(&self) -> FormatCapabilities;

    /// Convenience method to read with default options
    fn read_from_path(&self, path: &Path) -> Result<DataFrame> {
        self.read_from_path_with_options(path, &self.default_options())
    }

    /// Convenience method to write with default options
    fn write_to_path(&self, df: &DataFrame, path: &Path) -> Result<()> {
        self.write_to_path_with_options(df, path, &self.default_options())
    }
}

/// Format capabilities description
#[derive(Debug, Clone)]
pub struct FormatCapabilities {
    /// Supports reading
    pub can_read: bool,
    /// Supports writing
    pub can_write: bool,
    /// Supports streaming
    pub supports_streaming: bool,
    /// Supports schema evolution
    pub supports_schema_evolution: bool,
    /// Supports compression
    pub supports_compression: bool,
    /// Supports encryption
    pub supports_encryption: bool,
    /// Supports random access
    pub supports_random_access: bool,
    /// Supports append mode
    pub supports_append: bool,
    /// Maximum file size (if applicable)
    pub max_file_size: Option<usize>,
    /// Supported data types
    pub supported_types: Vec<FormatDataType>,
}

/// Data types supported by formats
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum FormatDataType {
    Boolean,
    Integer,
    Float,
    String,
    DateTime,
    Binary,
    Nested,
    Array,
    Map,
}

/// Trait for SQL-like operations
pub trait SqlOps: Send + Sync {
    /// Connect to the database
    fn connect(
        &self,
        connection_string: &str,
    ) -> Pin<Box<dyn Future<Output = Result<Box<dyn SqlConnection>>> + Send + '_>>;

    /// Execute a query and return results
    fn execute_query(
        &self,
        conn: &dyn SqlConnection,
        query: &str,
    ) -> Pin<Box<dyn Future<Output = Result<DataFrame>> + Send + '_>>;

    /// Execute a non-query statement
    fn execute_statement(
        &self,
        conn: &dyn SqlConnection,
        statement: &str,
    ) -> Pin<Box<dyn Future<Output = Result<SqlQueryResult>> + Send + '_>>;

    /// Insert DataFrame into a table
    fn insert_dataframe(
        &self,
        conn: &dyn SqlConnection,
        table_name: &str,
        df: &DataFrame,
    ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + '_>>;

    /// Create table from DataFrame schema
    fn create_table_from_dataframe(
        &self,
        conn: &dyn SqlConnection,
        table_name: &str,
        df: &DataFrame,
    ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + '_>>;

    /// List tables in the database
    fn list_tables(
        &self,
        conn: &dyn SqlConnection,
    ) -> Pin<Box<dyn Future<Output = Result<Vec<String>>> + Send + '_>>;

    /// Get table schema
    fn get_table_schema(
        &self,
        conn: &dyn SqlConnection,
        table_name: &str,
    ) -> Pin<Box<dyn Future<Output = Result<TableSchema>> + Send + '_>>;

    /// Check if table exists
    fn table_exists(
        &self,
        conn: &dyn SqlConnection,
        table_name: &str,
    ) -> Pin<Box<dyn Future<Output = Result<bool>> + Send + '_>>;

    /// Get database capabilities
    fn capabilities(&self) -> SqlCapabilities;
}

/// SQL connection trait
pub trait SqlConnection: Send + Sync {
    /// Execute a raw query
    fn execute_raw(
        &self,
        query: &str,
    ) -> Pin<Box<dyn Future<Output = Result<SqlQueryResult>> + Send + '_>>;

    /// Check if connection is valid
    fn is_valid(&self) -> bool;

    /// Close the connection
    fn close(&self) -> Pin<Box<dyn Future<Output = Result<()>> + Send + '_>>;

    /// Get connection metadata
    fn metadata(&self) -> HashMap<String, String>;
}

/// SQL query result
#[derive(Debug, Clone)]
pub struct SqlQueryResult {
    /// Number of rows affected
    pub rows_affected: u64,
    /// Execution time in milliseconds
    pub execution_time_ms: u64,
    /// Additional metadata
    pub metadata: HashMap<String, String>,
}

/// SQL capabilities description
#[derive(Debug, Clone)]
pub struct SqlCapabilities {
    /// Supports transactions
    pub supports_transactions: bool,
    /// Supports stored procedures
    pub supports_stored_procedures: bool,
    /// Supports user-defined functions
    pub supports_udf: bool,
    /// Supports window functions
    pub supports_window_functions: bool,
    /// Supports CTEs
    pub supports_cte: bool,
    /// Supports JSON data types
    pub supports_json: bool,
    /// Supports arrays
    pub supports_arrays: bool,
    /// Maximum connection pool size
    pub max_connections: Option<usize>,
    /// Supported SQL standard level
    pub sql_standard: SqlStandard,
}

/// SQL standard support levels
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum SqlStandard {
    Sql92,
    Sql99,
    Sql2003,
    Sql2006,
    Sql2008,
    Sql2011,
    Sql2016,
    Custom,
}

/// Table schema definition
#[derive(Debug, Clone)]
pub struct TableSchema {
    /// Table name
    pub name: String,
    /// Column definitions
    pub columns: Vec<ColumnDefinition>,
    /// Primary key columns
    pub primary_key: Vec<String>,
    /// Foreign key constraints
    pub foreign_keys: Vec<ForeignKeyConstraint>,
    /// Indexes
    pub indexes: Vec<IndexDefinition>,
    /// Table metadata
    pub metadata: HashMap<String, String>,
}

/// Column definition
#[derive(Debug, Clone)]
pub struct ColumnDefinition {
    /// Column name
    pub name: String,
    /// Data type
    pub data_type: SqlDataType,
    /// Whether nullable
    pub nullable: bool,
    /// Default value
    pub default_value: Option<String>,
    /// Column constraints
    pub constraints: Vec<ColumnConstraint>,
    /// Column metadata
    pub metadata: HashMap<String, String>,
}

/// SQL data types
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum SqlDataType {
    Boolean,
    SmallInt,
    Integer,
    BigInt,
    Real,
    Double,
    Decimal { precision: u8, scale: u8 },
    Char(u16),
    VarChar(Option<u16>),
    Text,
    Binary(u16),
    VarBinary(Option<u16>),
    Blob,
    Date,
    Time,
    Timestamp,
    TimestampWithTimeZone,
    Interval,
    Json,
    Xml,
    Array(Box<SqlDataType>),
    Custom(String),
}

/// Column constraints
#[derive(Debug, Clone, PartialEq, Eq)]
pub enum ColumnConstraint {
    NotNull,
    Unique,
    PrimaryKey,
    ForeignKey { table: String, column: String },
    Check(String),
    Default(String),
}

/// Foreign key constraint
#[derive(Debug, Clone)]
pub struct ForeignKeyConstraint {
    /// Constraint name
    pub name: String,
    /// Local columns
    pub columns: Vec<String>,
    /// Referenced table
    pub referenced_table: String,
    /// Referenced columns
    pub referenced_columns: Vec<String>,
    /// On delete action
    pub on_delete: ReferentialAction,
    /// On update action
    pub on_update: ReferentialAction,
}

/// Referential actions
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum ReferentialAction {
    NoAction,
    Restrict,
    Cascade,
    SetNull,
    SetDefault,
}

/// Index definition
#[derive(Debug, Clone)]
pub struct IndexDefinition {
    /// Index name
    pub name: String,
    /// Indexed columns
    pub columns: Vec<String>,
    /// Whether unique
    pub unique: bool,
    /// Index type
    pub index_type: IndexType,
    /// Index metadata
    pub metadata: HashMap<String, String>,
}

/// Index types
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum IndexType {
    BTree,
    Hash,
    Bitmap,
    FullText,
    Spatial,
    Custom(u8),
}

/// Trait for streaming operations
pub trait StreamingOps: Send + Sync {
    /// Create a new stream
    fn create_stream(
        &self,
        config: &HashMap<String, String>,
    ) -> Pin<Box<dyn Future<Output = Result<Box<dyn StreamHandle>>> + Send + '_>>;

    /// List available streams
    fn list_streams(&self) -> Pin<Box<dyn Future<Output = Result<Vec<String>>> + Send + '_>>;

    /// Check if stream exists
    fn stream_exists(
        &self,
        stream_name: &str,
    ) -> Pin<Box<dyn Future<Output = Result<bool>> + Send + '_>>;

    /// Get streaming capabilities
    fn capabilities(&self) -> StreamingCapabilities;
}

/// Stream handle trait
pub trait StreamHandle: Send + Sync {
    /// Read from stream
    fn read_batch(
        &self,
        batch_size: usize,
    ) -> Pin<Box<dyn Future<Output = Result<Option<DataFrame>>> + Send + '_>>;

    /// Write to stream
    fn write_batch(&self, df: &DataFrame) -> Pin<Box<dyn Future<Output = Result<()>> + Send + '_>>;

    /// Close stream
    fn close(&self) -> Pin<Box<dyn Future<Output = Result<()>> + Send + '_>>;

    /// Get stream metadata
    fn metadata(&self) -> HashMap<String, String>;
}

/// Streaming capabilities
#[derive(Debug, Clone)]
pub struct StreamingCapabilities {
    /// Supports real-time streaming
    pub supports_realtime: bool,
    /// Supports batch processing
    pub supports_batch: bool,
    /// Supports windowing
    pub supports_windowing: bool,
    /// Supports exactly-once processing
    pub supports_exactly_once: bool,
    /// Supports schema evolution
    pub supports_schema_evolution: bool,
    /// Maximum throughput (messages/sec)
    pub max_throughput: Option<u64>,
    /// Maximum latency (milliseconds)
    pub max_latency: Option<u64>,
    /// Supported serialization formats
    pub serialization_formats: Vec<SerializationFormat>,
}

/// Serialization formats
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum SerializationFormat {
    Json,
    Avro,
    Protobuf,
    MessagePack,
    Parquet,
    Arrow,
    Custom,
}

/// Format registry for managing file formats
pub struct FormatRegistry {
    /// Registered file formats
    formats: HashMap<String, Arc<dyn FileFormat>>,
    /// Registered SQL providers
    sql_providers: HashMap<String, Arc<dyn SqlOps>>,
    /// Registered streaming providers
    streaming_providers: HashMap<String, Arc<dyn StreamingOps>>,
}

impl FormatRegistry {
    /// Create a new format registry
    pub fn new() -> Self {
        Self {
            formats: HashMap::new(),
            sql_providers: HashMap::new(),
            streaming_providers: HashMap::new(),
        }
    }

    /// Register a file format
    pub fn register_format<F: FileFormat + 'static>(&mut self, format: F) {
        let name = format.format_name().to_string();
        self.formats.insert(name, Arc::new(format));
    }

    /// Register a SQL provider
    pub fn register_sql_provider<S: SqlOps + 'static>(&mut self, name: String, provider: S) {
        self.sql_providers.insert(name, Arc::new(provider));
    }

    /// Register a streaming provider
    pub fn register_streaming_provider<S: StreamingOps + 'static>(
        &mut self,
        name: String,
        provider: S,
    ) {
        self.streaming_providers.insert(name, Arc::new(provider));
    }

    /// Get format by name
    pub fn get_format(&self, name: &str) -> Option<Arc<dyn FileFormat>> {
        self.formats.get(name).cloned()
    }

    /// Get SQL provider by name
    pub fn get_sql_provider(&self, name: &str) -> Option<Arc<dyn SqlOps>> {
        self.sql_providers.get(name).cloned()
    }

    /// Get streaming provider by name
    pub fn get_streaming_provider(&self, name: &str) -> Option<Arc<dyn StreamingOps>> {
        self.streaming_providers.get(name).cloned()
    }

    /// Detect format for file
    pub fn detect_format(&self, path: &Path) -> Option<Arc<dyn FileFormat>> {
        for format in self.formats.values() {
            if format.can_handle_file(path) {
                return Some(Arc::clone(format));
            }
        }
        None
    }

    /// Detect format for data
    pub fn detect_format_from_data(&self, data: &[u8]) -> Option<Arc<dyn FileFormat>> {
        for format in self.formats.values() {
            if format.can_handle_data(data) {
                return Some(Arc::clone(format));
            }
        }
        None
    }

    /// List all registered formats
    pub fn list_formats(&self) -> Vec<String> {
        self.formats.keys().cloned().collect()
    }

    /// List all SQL providers
    pub fn list_sql_providers(&self) -> Vec<String> {
        self.sql_providers.keys().cloned().collect()
    }

    /// List all streaming providers
    pub fn list_streaming_providers(&self) -> Vec<String> {
        self.streaming_providers.keys().cloned().collect()
    }

    /// Get all format capabilities
    pub fn get_all_capabilities(&self) -> HashMap<String, FormatCapabilities> {
        self.formats
            .iter()
            .map(|(name, format)| (name.clone(), format.capabilities()))
            .collect()
    }
}

impl Default for FormatRegistry {
    fn default() -> Self {
        Self::new()
    }
}

/// Unified data operations trait
pub trait DataOperations {
    /// Read data from any supported source
    fn read_data(
        &self,
        source: &DataSource,
    ) -> Pin<Box<dyn Future<Output = Result<DataFrame>> + Send + '_>>;

    /// Write data to any supported destination
    fn write_data(
        &self,
        df: &DataFrame,
        destination: &DataDestination,
    ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + '_>>;

    /// Copy data between sources
    fn copy_data(
        &self,
        source: &DataSource,
        destination: &DataDestination,
    ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + '_>>;

    /// Transform data using a pipeline
    fn transform_data(
        &self,
        source: &DataSource,
        pipeline: &TransformPipeline,
        destination: &DataDestination,
    ) -> Pin<Box<dyn Future<Output = Result<()>> + Send + '_>>;
}

/// Data source specification
#[derive(Debug, Clone)]
pub enum DataSource {
    File {
        path: String,
        format: Option<String>,
        options: HashMap<String, String>,
    },
    Sql {
        connection: String,
        query: String,
        options: HashMap<String, String>,
    },
    Stream {
        provider: String,
        stream_name: String,
        options: HashMap<String, String>,
    },
    Url {
        url: String,
        format: Option<String>,
        options: HashMap<String, String>,
    },
    Memory {
        data: Vec<u8>,
        format: String,
    },
}

/// Data destination specification
#[derive(Debug, Clone)]
pub enum DataDestination {
    File {
        path: String,
        format: Option<String>,
        options: HashMap<String, String>,
    },
    Sql {
        connection: String,
        table: String,
        options: HashMap<String, String>,
    },
    Stream {
        provider: String,
        stream_name: String,
        options: HashMap<String, String>,
    },
    Memory {
        format: String,
        options: HashMap<String, String>,
    },
}

/// Transform pipeline specification
#[derive(Debug, Clone)]
pub struct TransformPipeline {
    /// Pipeline stages
    pub stages: Vec<TransformStage>,
    /// Pipeline options
    pub options: HashMap<String, String>,
}

/// Transform stage
#[derive(Debug, Clone)]
pub enum TransformStage {
    Filter {
        condition: String,
    },
    Map {
        expression: String,
    },
    Aggregate {
        group_by: Vec<String>,
        aggregations: HashMap<String, String>,
    },
    Join {
        other_source: DataSource,
        on: Vec<String>,
        join_type: JoinType,
    },
    Window {
        partition_by: Vec<String>,
        order_by: Vec<String>,
        window_spec: String,
    },
    Custom {
        name: String,
        parameters: HashMap<String, String>,
    },
}

/// Join types
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum JoinType {
    Inner,
    Left,
    Right,
    Full,
    Cross,
    LeftSemi,
    LeftAnti,
}

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

    /// Mock file format for testing
    struct MockFormat;

    impl FileFormat for MockFormat {
        fn format_name(&self) -> &'static str {
            "mock"
        }

        fn file_extensions(&self) -> Vec<&'static str> {
            vec!["mock", "test"]
        }

        fn mime_types(&self) -> Vec<&'static str> {
            vec!["application/mock"]
        }

        fn can_handle_file(&self, path: &Path) -> bool {
            path.extension()
                .and_then(|ext| ext.to_str())
                .map(|ext| self.file_extensions().contains(&ext))
                .unwrap_or(false)
        }

        fn can_handle_data(&self, data: &[u8]) -> bool {
            data.starts_with(b"MOCK")
        }

        fn read_from_path_with_options(
            &self,
            _path: &Path,
            _options: &HashMap<String, String>,
        ) -> Result<DataFrame> {
            Err(Error::InvalidOperation(
                "Mock format read not implemented".to_string(),
            ))
        }

        fn read_from_bytes_with_options(
            &self,
            _data: &[u8],
            _options: &HashMap<String, String>,
        ) -> Result<DataFrame> {
            Err(Error::InvalidOperation(
                "Mock format read not implemented".to_string(),
            ))
        }

        fn write_to_path_with_options(
            &self,
            _df: &DataFrame,
            _path: &Path,
            _options: &HashMap<String, String>,
        ) -> Result<()> {
            Err(Error::InvalidOperation(
                "Mock format write not implemented".to_string(),
            ))
        }

        fn write_to_bytes_with_options(
            &self,
            _df: &DataFrame,
            _options: &HashMap<String, String>,
        ) -> Result<Vec<u8>> {
            Err(Error::InvalidOperation(
                "Mock format write not implemented".to_string(),
            ))
        }

        fn get_metadata(&self, _path: &Path) -> Result<HashMap<String, String>> {
            Ok(HashMap::new())
        }

        fn validate_options(&self, _options: &HashMap<String, String>) -> Result<()> {
            Ok(())
        }

        fn default_options(&self) -> HashMap<String, String> {
            HashMap::new()
        }

        fn capabilities(&self) -> FormatCapabilities {
            FormatCapabilities {
                can_read: true,
                can_write: true,
                supports_streaming: false,
                supports_schema_evolution: false,
                supports_compression: false,
                supports_encryption: false,
                supports_random_access: false,
                supports_append: false,
                max_file_size: None,
                supported_types: vec![
                    FormatDataType::Boolean,
                    FormatDataType::Integer,
                    FormatDataType::Float,
                    FormatDataType::String,
                ],
            }
        }
    }

    #[test]
    fn test_format_registry() {
        let mut registry = FormatRegistry::new();
        registry.register_format(MockFormat);

        assert!(registry.get_format("mock").is_some());
        assert!(registry.get_format("nonexistent").is_none());

        let formats = registry.list_formats();
        assert!(formats.contains(&"mock".to_string()));

        let capabilities = registry.get_all_capabilities();
        assert!(capabilities.contains_key("mock"));
    }

    #[test]
    fn test_format_detection() {
        let mut registry = FormatRegistry::new();
        registry.register_format(MockFormat);

        let path = Path::new("test.mock");
        let detected = registry.detect_format(path);
        assert!(detected.is_some());
        assert_eq!(
            detected.expect("operation should succeed").format_name(),
            "mock"
        );

        let data = b"MOCK format data";
        let detected = registry.detect_format_from_data(data);
        assert!(detected.is_some());
        assert_eq!(
            detected.expect("operation should succeed").format_name(),
            "mock"
        );

        let invalid_data = b"Not mock data";
        let detected = registry.detect_format_from_data(invalid_data);
        assert!(detected.is_none());
    }

    #[test]
    fn test_data_source() {
        let source = DataSource::File {
            path: "test.csv".to_string(),
            format: Some("csv".to_string()),
            options: HashMap::new(),
        };

        match source {
            DataSource::File { path, format, .. } => {
                assert_eq!(path, "test.csv");
                assert_eq!(format, Some("csv".to_string()));
            }
            _ => panic!("Expected File source"),
        }
    }

    #[test]
    fn test_table_schema() {
        let schema = TableSchema {
            name: "test_table".to_string(),
            columns: vec![
                ColumnDefinition {
                    name: "id".to_string(),
                    data_type: SqlDataType::Integer,
                    nullable: false,
                    default_value: None,
                    constraints: vec![ColumnConstraint::PrimaryKey],
                    metadata: HashMap::new(),
                },
                ColumnDefinition {
                    name: "name".to_string(),
                    data_type: SqlDataType::VarChar(Some(255)),
                    nullable: true,
                    default_value: Some("''".to_string()),
                    constraints: vec![],
                    metadata: HashMap::new(),
                },
            ],
            primary_key: vec!["id".to_string()],
            foreign_keys: vec![],
            indexes: vec![],
            metadata: HashMap::new(),
        };

        assert_eq!(schema.name, "test_table");
        assert_eq!(schema.columns.len(), 2);
        assert_eq!(schema.columns[0].name, "id");
        assert_eq!(schema.columns[0].data_type, SqlDataType::Integer);
        assert!(!schema.columns[0].nullable);
        assert_eq!(schema.primary_key, vec!["id"]);
    }

    #[test]
    fn test_transform_pipeline() {
        let pipeline = TransformPipeline {
            stages: vec![
                TransformStage::Filter {
                    condition: "age > 18".to_string(),
                },
                TransformStage::Aggregate {
                    group_by: vec!["department".to_string()],
                    aggregations: {
                        let mut agg = HashMap::new();
                        agg.insert("salary".to_string(), "avg".to_string());
                        agg.insert("count".to_string(), "count".to_string());
                        agg
                    },
                },
            ],
            options: HashMap::new(),
        };

        assert_eq!(pipeline.stages.len(), 2);

        match &pipeline.stages[0] {
            TransformStage::Filter { condition } => {
                assert_eq!(condition, "age > 18");
            }
            _ => panic!("Expected Filter stage"),
        }

        match &pipeline.stages[1] {
            TransformStage::Aggregate {
                group_by,
                aggregations,
            } => {
                assert_eq!(group_by, &vec!["department".to_string()]);
                assert_eq!(aggregations.len(), 2);
                assert_eq!(aggregations.get("salary"), Some(&"avg".to_string()));
            }
            _ => panic!("Expected Aggregate stage"),
        }
    }
}
