% This program needs to be merged with PCLU's "misc" library
% to use the random number generator.
%
% pclu -merge $CLUHOME/lib/misc.lib -compile rpg_gen.clu

% Seed the random number generator with the current time
init_rng = proc ()
    d: date := now()
    seed: int := ((d.hour*60) + d.minute)*60 + d.second
    random$seed(seed)
end init_rng

character = cluster is generate
    rep = null

    % Roll a die
    roll_die = proc () returns (int)
        return (1 + random$next(6))
    end roll_die

    % Roll four dice and get the sum of the highest three rolls
    roll_four_times = proc () returns (int)
        lowest: int := 7 % higher than any dice roll
        sum: int := 0
        for i: int in int$from_to(1,4) do
            roll: int := roll_die()
            sum := sum + roll
            if roll < lowest then lowest := roll end
        end
        return (sum - lowest)
    end roll_four_times

    % Try to generate a character by rolling six values
    try_generate = proc () returns (sequence[int])
        rolls: sequence[int] := sequence[int]$[]
        for i: int in int$from_to(1,6) do
            rolls := sequence[int]$addh(rolls, roll_four_times())
        end
        return (rolls)
    end try_generate

    % See if a character is valid
    valid = proc (c: sequence[int]) returns (bool)
        total: int := 0
        at_least_15: int := 0
        for i: int in sequence[int]$elements(c) do
            total := total + i
            if i >= 15 then at_least_15 := at_least_15 + 1 end
        end
        return (total >= 75 & at_least_15 >= 2)
    end valid

    % Generate a character
    generate = proc () returns (sequence[int])
        while true do
            c: sequence[int] := try_generate()
            if valid(c) then return(c) end
        end
    end generate
end character

% Generate a character and display the six values
start_up = proc ()
    po: stream := stream$primary_output()
    init_rng()
    hero: sequence[int] := character$generate()
    for stat: int in sequence[int]$elements(hero) do
        stream$putright(po, int$unparse(stat), 4)
    end
end start_up