r-database/src/database/table.rs

use serde::{Deserialize, Serialize};
use std::{collections::HashMap, fs};
use super::{index::Index, row::Row};


#[derive(Serialize, Deserialize)] 
pub struct Table {
  indexes: Vec<Index>,
  rows: HashMap<u64, Row>,
  name: String,
  pk_key: String,
}

impl Table {

  pub fn new(name: &str, pk_key: &str) -> Table {
    Table { indexes: vec![], rows: HashMap::new(), name: name.to_string(), pk_key: pk_key.to_string() }
  }

  pub fn from_file(file_path: String) -> Result<Table, &'static str> {
    let serialized = fs::read_to_string(file_path);
    if serialized.is_err() {
      return Err("Failed loading from file");
    }
    let table: Table = serde_json::from_str(&serialized.unwrap()).unwrap();
    return Ok(table);
  }
  
  pub fn to_file(&self, file_path: &'static str) {

    let serialized = serde_json::to_string(self).unwrap();
    println!("serialized = {}", serialized);
    let result = fs::write(file_path, serialized);
    if result.is_err() {
      panic!("Failed writing table to file")
    }
  }


  pub fn create_index(&mut self, index: Index) {
    // TODO: Add row indexes to the index itself before pushing to the table
    self.indexes.push(index)
  }

  pub fn find_by_pk(&self, value: &u64) -> Result<&Row, &'static str> {
    let row = self.rows.get(value);
    if row.is_none() {
      return Err("Row not found!");
    }
    Ok(row.unwrap().clone())
  }

  pub fn insert_row(&mut self, row: Row) {
    let key_option = row.columns.get(&self.pk_key);
    
    if key_option.is_none() {
      panic!("Primary key not found on row to insert!");
    }
    
    let key = key_option.unwrap().as_u64();
    
    if key.is_none() {
      panic!("Primary key is not of type u64");
    }

    self.rows.insert(key.unwrap(), row);
  }
}