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use std::collections::HashMap;

use crate::schema::Schema;
use crate::types::DataType;
use crate::value::Value;

pub struct Environment {
    /// Data schema information contains table, fields names and types
    pub schema: Schema,
    /// All Global Variables values that can life for this program session
    pub globals: HashMap<String, Value>,
    /// All Global Variables Types that can life for this program session
    pub globals_types: HashMap<String, DataType>,
    /// Local variables types in the current scope, later will be multi layer scopes
    pub scopes: HashMap<String, DataType>,
}

impl Environment {
    /// Create new [`Environment`] instance with Data Schema
    pub fn new(schema: Schema) -> Self {
        Self {
            schema,
            globals: HashMap::default(),
            globals_types: HashMap::default(),
            scopes: HashMap::default(),
        }
    }

    /// Define in the current scope
    pub fn define(&mut self, str: String, data_type: DataType) {
        self.scopes.insert(str, data_type);
    }

    /// Define in the global scope
    pub fn define_global(&mut self, str: String, data_type: DataType) {
        self.globals_types.insert(str, data_type);
    }

    /// Returns true if local or global scopes has contains field
    pub fn contains(&self, str: &String) -> bool {
        self.scopes.contains_key(str) || self.globals_types.contains_key(str)
    }

    /// Resolve Global or Local type using symbol name
    pub fn resolve_type(&self, str: &String) -> Option<&DataType> {
        if str.starts_with('@') {
            return self.globals_types.get(str);
        }
        return self.scopes.get(str);
    }

    /// Clear all locals scopes and only save globals
    pub fn clear_session(&mut self) {
        self.scopes.clear()
    }
}