ex08.cairo

######### Ex 08
## Recursions - basics
# In this exercice, you need to:
# - Use this contract's claim_points() function
# - Your points are credited by the contract



%lang starknet
%builtins pedersen range_check

from starkware.cairo.common.cairo_builtins import HashBuiltin
from starkware.cairo.common.math import (assert_not_zero, assert_le)

from contracts.utils.ex00_base import (
    tderc20_address,
    has_validated_exercice,
    distribute_points,
    validate_exercice,
    ex_initializer
)

#
# Declaring storage vars
# Storage vars are by default not visible through the ABI. They are similar to "private" variables in Solidity
#

@storage_var
func user_values_storage(account: felt, slot: felt) -> (user_values_storage: felt):
end


#
# Declaring getters
# Public variables should be declared explicitly with a getter
#

@view
func user_values{syscall_ptr : felt*, pedersen_ptr : HashBuiltin*, range_check_ptr}(account: felt, slot: felt) -> (value: felt):
    let (value) = user_values_storage.read(account, slot)
    return (value)
end

#
# Constructor
#
@constructor
func constructor{syscall_ptr : felt*, pedersen_ptr : HashBuiltin*, range_check_ptr}(
        _tderc20_address : felt):
	ex_initializer(_tderc20_address)
    return ()
end

#
# External functions
# Calling this function will simply credit 2 points to the address specified in parameter
#

@external
func claim_points{syscall_ptr : felt*, pedersen_ptr : HashBuiltin*, range_check_ptr}(account: felt, salt: felt):
    # Important: due to the way transaction hashes are calculated currently, you'll need to change salt everytime you call this function.
    # Otherwise, the transaction hash will stay the same and your transaction won't execute the following iteration

    # Checking the value of user_values_storage for the user, at slot 10
    let (user_value_at_slot_ten) = user_values_storage.read(account, 10)

    # This value should be equal to 10
    assert user_value_at_slot_ten = 10

    # Checking if the user has validated the exercice before
    validate_exercice(account)
    # Sending points to the address specified as parameter
    distribute_points(account, 2)
    return ()
end

# This function takes an array as a parameter
# In order to pass it, the user needs to pass both the array and its length
# This complexity is abstracted away by voyager, where you simply need to pass an array
@external
func set_user_values{syscall_ptr : felt*, pedersen_ptr : HashBuiltin*, range_check_ptr}(account: felt, array_len: felt, array: felt*):

    set_user_values_internal(account, array_len, array)
    return ()
end

#
# Internal functions
#
#

func set_user_values_internal{syscall_ptr : felt*, pedersen_ptr : HashBuiltin*, range_check_ptr}(account:felt, length : felt, array : felt*):
    # This function is used recursively to set all the user values
    # Recursively, we first go through the length of the array
    # Once at the end of the array (length = 0), we start summing
    if length == 0:
        # Start with sum=0.
        return ()
    end

    # If length is NOT zero, then the function calls itself again, moving forward one slot
    set_user_values_internal(account = account, length=length - 1, array=array + 1)

    # This part of the function is first reached when length=0.
    user_values_storage.write(account, length - 1, [array])
    return ()
end