element.sh

#!/bin/bash
PSQL="psql -X --username=freecodecamp --dbname=periodic_table --tuples-only -c"

if [[ -z $1 ]]
then
  echo "Please provide an element as an argument."
else
  if [[ ! $1 =~ ^[0-9]+$ ]]
  then
    ELEMENT_SYMBOL=$($PSQL "SELECT * FROM elements FULL JOIN properties USING(atomic_number) FULL JOIN types USING(type_id) WHERE symbol='$1'")
    ELEMENT_NAME=$($PSQL "SELECT * FROM elements FULL JOIN properties USING(atomic_number) FULL JOIN types USING(type_id) WHERE name='$1'")
    if [[ $ELEMENT_SYMBOL ]]
    then

      echo $ELEMENT_SYMBOL | while read TYPE_ID BAR ATOMIC_NUMBER BAR SYMBOL BAR NAME BAR ATOMIC_MASS BAR MELTING_POINT BAR BOILING_POINT BER TYPE
      do
        echo "The element with atomic number $ATOMIC_NUMBER is $NAME ($SYMBOL). It's a $TYPE, with a mass of $ATOMIC_MASS amu. $NAME has a melting point of $MELTING_POINT celsius and a boiling point of $BOILING_POINT celsius."
      done

    elif [[ $ELEMENT_NAME ]]
    then

      echo $ELEMENT_NAME | while read TYPE_ID BAR ATOMIC_NUMBER BAR SYMBOL BAR NAME BAR ATOMIC_MASS BAR MELTING_POINT BAR BOILING_POINT BER TYPE
      do
        echo "The element with atomic number $ATOMIC_NUMBER is $NAME ($SYMBOL). It's a $TYPE, with a mass of $ATOMIC_MASS amu. $NAME has a melting point of $MELTING_POINT celsius and a boiling point of $BOILING_POINT celsius."
      done
       
    else
      echo "I could not find that element in the database."
    fi
  
  else
    ELEMENT_NUMBER=$($PSQL "SELECT * FROM elements FULL JOIN properties USING(atomic_number) FULL JOIN types USING(type_id) WHERE atomic_number=$1")
    if [[ $ELEMENT_NUMBER ]]
    then
      echo $ELEMENT_NUMBER | while read TYPE_ID BAR ATOMIC_NUMBER BAR SYMBOL BAR NAME BAR ATOMIC_MASS BAR MELTING_POINT BAR BOILING_POINT BER TYPE
      do
        echo "The element with atomic number $ATOMIC_NUMBER is $NAME ($SYMBOL). It's a $TYPE, with a mass of $ATOMIC_MASS amu. $NAME has a melting point of $MELTING_POINT celsius and a boiling point of $BOILING_POINT celsius."
      done
    else
      echo "I could not find that element in the database."
    fi
  fi
fi