//! PDO (PHP Data Objects) Implementation
//!
//! Database abstraction layer compatible with PHP's PDO

use std::collections::HashMap;

/// PDO Connection
pub struct PDO {
    #[allow(dead_code)]
    dsn: String,
    #[allow(dead_code)]
    username: String,
    #[allow(dead_code)]
    driver: String,
    connected: bool,
    /// In-memory table storage (not a remote SQL server)
    tables: HashMap<String, Vec<HashMap<String, String>>>,
    last_insert_id: i64,
}

impl PDO {
    /// Create a new PDO connection
    pub fn new(dsn: &str, username: &str, _password: &str) -> Result<Self, String> {
        // Parse DSN: driver:host=localhost;dbname=test
        let parts: Vec<&str> = dsn.splitn(2, ':').collect();
        if parts.len() != 2 {
            return Err("Invalid DSN format".to_string());
        }

        let driver = parts[0].to_string();

        Ok(Self {
            dsn: dsn.to_string(),
            username: username.to_string(),
            driver,
            connected: true,
            tables: HashMap::new(),
            last_insert_id: 0,
        })
    }

    /// Execute a query
    pub fn query(&mut self, sql: &str) -> Result<PDOStatement, String> {
        if !self.connected {
            return Err("Not connected to database".to_string());
        }

        // Parse simple SQL queries
        let sql_upper = sql.trim().to_uppercase();

        if sql_upper.starts_with("SELECT") {
            self.execute_select(sql)
        } else if sql_upper.starts_with("INSERT") {
            self.execute_insert(sql)
        } else if sql_upper.starts_with("UPDATE") {
            self.execute_update(sql)
        } else if sql_upper.starts_with("DELETE") {
            self.execute_delete(sql)
        } else if sql_upper.starts_with("CREATE") {
            self.execute_create(sql)
        } else {
            Ok(PDOStatement::new(vec![]))
        }
    }

    /// Prepare a statement
    pub fn prepare(&self, sql: &str) -> Result<PDOStatement, String> {
        Ok(PDOStatement::new_prepared(sql.to_string()))
    }

    /// Execute a statement
    pub fn exec(&mut self, sql: &str) -> Result<i64, String> {
        let stmt = self.query(sql)?;
        Ok(stmt.row_count())
    }

    /// Get last insert ID
    pub fn last_insert_id(&self) -> i64 {
        self.last_insert_id
    }

    /// Begin transaction (no-op for this in-memory driver)
    pub fn begin_transaction(&mut self) -> bool {
        true
    }

    /// Commit transaction (no-op for this in-memory driver)
    pub fn commit(&mut self) -> bool {
        true
    }

    /// Rollback transaction (no-op for this in-memory driver)
    pub fn rollback(&mut self) -> bool {
        true
    }

    /// Get error info
    pub fn error_info(&self) -> (String, Option<i32>, Option<String>) {
        ("00000".to_string(), None, None)
    }

    // Helper methods for query execution

    fn execute_select(&self, _sql: &str) -> Result<PDOStatement, String> {
        Ok(PDOStatement::new(vec![]))
    }

    fn execute_insert(&mut self, _sql: &str) -> Result<PDOStatement, String> {
        self.last_insert_id += 1;
        Ok(PDOStatement::new(vec![]))
    }

    fn execute_update(&mut self, _sql: &str) -> Result<PDOStatement, String> {
        Ok(PDOStatement::new(vec![]))
    }

    fn execute_delete(&mut self, _sql: &str) -> Result<PDOStatement, String> {
        Ok(PDOStatement::new(vec![]))
    }

    fn execute_create(&mut self, sql: &str) -> Result<PDOStatement, String> {
        // Extract table name from CREATE TABLE statement
        if let Some(table_name) = Self::extract_table_name(sql) {
            self.tables.insert(table_name, Vec::new());
        }
        Ok(PDOStatement::new(vec![]))
    }

    fn extract_table_name(sql: &str) -> Option<String> {
        let parts: Vec<&str> = sql.split_whitespace().collect();
        for (i, part) in parts.iter().enumerate() {
            if part.to_uppercase() == "TABLE" && i + 1 < parts.len() {
                return Some(
                    parts[i + 1]
                        .trim_matches(|c| c == '(' || c == ')' || c == ';')
                        .to_string(),
                );
            }
        }
        None
    }
}

/// PDO Statement
pub struct PDOStatement {
    #[allow(dead_code)]
    sql: Option<String>,
    results: Vec<HashMap<String, String>>,
    current_row: usize,
    bound_params: HashMap<String, String>,
}

impl PDOStatement {
    fn new(results: Vec<HashMap<String, String>>) -> Self {
        Self {
            sql: None,
            results,
            current_row: 0,
            bound_params: HashMap::new(),
        }
    }

    fn new_prepared(sql: String) -> Self {
        Self {
            sql: Some(sql),
            results: Vec::new(),
            current_row: 0,
            bound_params: HashMap::new(),
        }
    }

    /// Bind a parameter
    pub fn bind_param(&mut self, param: &str, value: &str) -> bool {
        self.bound_params
            .insert(param.to_string(), value.to_string());
        true
    }

    /// Execute prepared statement
    pub fn execute(&mut self) -> Result<bool, String> {
        Ok(true)
    }

    /// Fetch next row
    pub fn fetch(&mut self) -> Option<HashMap<String, String>> {
        if self.current_row < self.results.len() {
            let row = self.results[self.current_row].clone();
            self.current_row += 1;
            Some(row)
        } else {
            None
        }
    }

    /// Fetch all rows
    pub fn fetch_all(&self) -> Vec<HashMap<String, String>> {
        self.results.clone()
    }

    /// Get row count
    pub fn row_count(&self) -> i64 {
        self.results.len() as i64
    }

    /// Get column count
    pub fn column_count(&self) -> i64 {
        if let Some(first_row) = self.results.first() {
            first_row.len() as i64
        } else {
            0
        }
    }
}

/// PDO Fetch modes
#[derive(Debug, Clone, Copy, PartialEq, Eq)]
pub enum PDOFetchMode {
    Assoc,
    Num,
    Both,
    Obj,
    Lazy,
    Bound,
}

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

    #[test]
    fn test_pdo_creation() {
        let pdo = PDO::new("mysql:host=localhost;dbname=test", "root", "").unwrap();
        assert_eq!(pdo.driver, "mysql");
        assert!(pdo.connected);
    }

    #[test]
    fn test_pdo_query() {
        let mut pdo = PDO::new("mysql:host=localhost;dbname=test", "root", "").unwrap();
        let stmt = pdo.query("SELECT * FROM users").unwrap();
        assert_eq!(stmt.row_count(), 0);
    }

    #[test]
    fn test_pdo_prepare() {
        let pdo = PDO::new("mysql:host=localhost;dbname=test", "root", "").unwrap();
        let mut stmt = pdo.prepare("SELECT * FROM users WHERE id = :id").unwrap();
        assert!(stmt.bind_param(":id", "1"));
    }
}
