TDERC20.cairo

%lang starknet

from starkware.cairo.common.cairo_builtins import HashBuiltin
from starkware.cairo.common.uint256 import Uint256
from starkware.starknet.common.syscalls import get_caller_address

from contracts.token.ERC20_base import (
    ERC20_name,
    ERC20_symbol,
    ERC20_totalSupply,
    ERC20_decimals,
    ERC20_balanceOf,
    ERC20_allowance,
    ERC20_mint,
    ERC20_burn,
    ERC20_initializer,
    ERC20_approve,
    ERC20_increaseAllowance,
    ERC20_decreaseAllowance,
    ERC20_transfer,
    ERC20_transferFrom
)

@storage_var
func teachers_and_exercises_accounts(account: felt) -> (balance: felt):
end

@storage_var
func is_transferable_storage() -> (is_transferable_storage : felt):
end

@constructor
func constructor{
        syscall_ptr: felt*, 
        pedersen_ptr: HashBuiltin*,
        range_check_ptr
    }(
        name: felt,
        symbol: felt,
        initial_supply: Uint256,
        recipient: felt,
        owner: felt
    ):
    ERC20_initializer(name, symbol, initial_supply, recipient)
    teachers_and_exercises_accounts.write(owner, 1)
    return ()
end

#
# Getters
#

@view
func is_transferable{
        syscall_ptr : felt*,
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }() -> (is_transferable: felt):
    let (is_transferable) = is_transferable_storage.read()
    return (is_transferable)
end

@view
func name{
        syscall_ptr : felt*,
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }() -> (name: felt):
    let (name) = ERC20_name()
    return (name)
end

@view
func symbol{
        syscall_ptr : felt*,
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }() -> (symbol: felt):
    let (symbol) = ERC20_symbol()
    return (symbol)
end

@view
func totalSupply{
        syscall_ptr : felt*, 
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }() -> (totalSupply: Uint256):
    let (totalSupply: Uint256) = ERC20_totalSupply()
    return (totalSupply)
end

@view
func decimals{
        syscall_ptr : felt*, 
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }() -> (decimals: felt):
    let (decimals) = ERC20_decimals()
    return (decimals)
end

@view
func balanceOf{
        syscall_ptr : felt*, 
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }(account: felt) -> (balance: Uint256):
    let (balance: Uint256) = ERC20_balanceOf(account)
    return (balance)
end

@view
func allowance{
        syscall_ptr : felt*, 
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }(owner: felt, spender: felt) -> (remaining: Uint256):
    let (remaining: Uint256) = ERC20_allowance(owner, spender)
    return (remaining)
end

#
# Externals
#

@external
func transfer{
        syscall_ptr : felt*, 
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }(recipient: felt, amount: Uint256) -> (success: felt):
    _is_transferable()
    ERC20_transfer(recipient, amount)
    # Cairo equivalent to 'return (true)'
    return (1)
end

@external
func transferFrom{
        syscall_ptr : felt*, 
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }(
        sender: felt, 
        recipient: felt, 
        amount: Uint256
    ) -> (success: felt):
    _is_transferable()
    ERC20_transferFrom(sender, recipient, amount)
    # Cairo equivalent to 'return (true)'
    return (1)
end

@external
func approve{
        syscall_ptr : felt*, 
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }(spender: felt, amount: Uint256) -> (success: felt):
    ERC20_approve(spender, amount)
    # Cairo equivalent to 'return (true)'
    return (1)
end

@external
func increaseAllowance{
        syscall_ptr : felt*, 
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }(spender: felt, added_value: Uint256) -> (success: felt):
    ERC20_increaseAllowance(spender, added_value)
    # Cairo equivalent to 'return (true)'
    return (1)
end

@external
func decreaseAllowance{
        syscall_ptr : felt*, 
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }(spender: felt, subtracted_value: Uint256) -> (success: felt):
    ERC20_decreaseAllowance(spender, subtracted_value)
    # Cairo equivalent to 'return (true)'
    return (1)
end

@external
func distribute_points{
        syscall_ptr: felt*,
        pedersen_ptr: HashBuiltin*,
        range_check_ptr
    }(to: felt, amount: Uint256):
    only_teacher_or_exercice()
    ERC20_mint(to, amount)
    return ()
end

@external
func remove_points{
        syscall_ptr: felt*,
        pedersen_ptr: HashBuiltin*,
        range_check_ptr
    }(to: felt, amount: Uint256):
    only_teacher_or_exercice()
    ERC20_burn(to, amount)
    return ()
end

@external
func set_teacher{
        syscall_ptr: felt*,
        pedersen_ptr: HashBuiltin*,
        range_check_ptr
    }(account: felt, permission: felt):
    only_teacher_or_exercice()
    teachers_and_exercises_accounts.write(account, permission)

    return ()
end

@external
func set_teachers{
        syscall_ptr: felt*,
        pedersen_ptr: HashBuiltin*,
        range_check_ptr
    }(accounts_len: felt, accounts: felt*):
    only_teacher_or_exercice()
    _set_teacher(accounts_len, accounts)
    return ()
end

@external
func set_transferable{
        syscall_ptr: felt*,
        pedersen_ptr: HashBuiltin*,
        range_check_ptr
    }(permission: felt):
    only_teacher_or_exercice()
    _set_transferable(permission)
    return ()
end

@view
func is_teacher_or_exercise{
        syscall_ptr : felt*, 
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }(account: felt) -> (permission: felt):
    let (permission: felt) = teachers_and_exercises_accounts.read(account)
    return (permission)
end


func _set_teacher{
        syscall_ptr: felt*,
        pedersen_ptr: HashBuiltin*,
        range_check_ptr
    }(accounts_len: felt, accounts: felt*):

    if accounts_len == 0:
        # Start with sum=0.
        return ()
    end

    # If length is NOT zero, then the function calls itself again, by moving forward one slot
    _set_teacher(accounts_len=accounts_len - 1, accounts=accounts + 1)

    # This part of the function is first reached when length=0.
    teachers_and_exercises_accounts.write([accounts], 1)
    return ()
end

func only_teacher_or_exercice{
        syscall_ptr : felt*, 
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }():
    let (caller) = get_caller_address()
    let (permission) = teachers_and_exercises_accounts.read(account=caller)
    assert permission = 1
    return ()
end

func _is_transferable{
        syscall_ptr : felt*, 
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }():
    let (permission) = is_transferable_storage.read()
    assert permission = 1
    return ()
end

func _set_transferable{
        syscall_ptr : felt*, 
        pedersen_ptr : HashBuiltin*,
        range_check_ptr
    }(permission: felt):
    is_transferable_storage.write(permission)
    return()
end