tic tac toe

ttt.lua

local string = require"string"
local fmt = string.format

--on adding computer player
-- math.random(upper) 
-- math.random(lower, upper) 

-- ==&== BOARD ==&==

local function new_board()
    return {{" "," "," "},
            {" "," "," "},
            {" "," "," "}}
end

local function print_board(board)
    local function print_row(row)
        for col = 1,2 do
            io.write(fmt(" %s |",board[row][col]))
        end
        io.write(fmt(" %s \n", board[row][3]))
    end
    for row = 1, 2 do
        print_row(row)
        io.write("___|___|___\n")
    end
    print_row(3)
    io.write("   |   |   \n")
end

-- ==&== CHECK ==&==

--NOTE: for check functions:
--returns nil               for no matches or match of " " 
--        players letter    for match of anything else
local function check_col(board, col)
    for row = 1, 2 do
        if board[row][col] ~= board[row+1][col] then
            return nil
        end
    end
    if board [1][col] ~= " " then
        return board[1][col]
    end
    return nil
end

local function check_row(board, row)
    for col = 1, 2 do
        if board[row][col] ~= board[row][col+1] then
            return nil
        end
    end
    if board [row][1] ~= " " then
        return board[row][1]
    end
    return nil
end

-- NOTE:
-- up diagonal is _ _ X
--                _ X _
--                X _ _
-- not up is the other diagonal
local function check_diag(board, check_up)
    if check_up then
        if board[1][3] == board[2][2] and board[2][2] == board[3][1] then
            if board[2][2] ~= " " then
                return board[2][2]
            end
        end
    else
        if board[1][1] == board[2][2] and board[2][2] == board[3][3] then
            if board[2][2] ~= " " then
                return board[2][2]
            end
        end
    end
    return nil
end

local function check_board(board)
    local ret
    for i=1,3 do
        ret = ret or check_col(board, i)
        ret = ret or check_row(board, i)
    end
    ret = ret or check_diag(board, true)
    ret = ret or check_diag(board, false)
    return ret
end

-- ==&== READ ==&==

local function read_for_and_put_coord(board, letter)
    while true do
        local input = io.read()
        if input ~= "" then --just pressing enter does not give error but io.read loop continues
            local _, _, x, y = string.find(input, "%s-(%d)%s+(%d)")
            x = tonumber(x)
            y = tonumber(y)
            if x and y then
                if x < 4 and x > 0 and y < 4 and y >0 then
                    --NOTE: coords seem flipped here
                    --      b/c indexing the board goes
                    --        [row][column]
                    --      but in reality x corresponds to col and y corresponds to row
                    if board[y][x] == " " then
                        board[y][x] = letter
                        break
                    else
                        io.write("HEY someones already put a letter there!!!\n")
                    end
                else
                    io.write(fmt("sadly, you cant put your letter at (%d, %d)\n", x, y))
                end
            else
                io.write("you cant put your letter... there...(o.O\n")
            end
            io.write("please try again...\n")
        end
    end
end

local function read_for_letter()
    while true do
        local _,_,ret = string.find(io.read(), "%s-(.)")
        if ret then
            return ret
        end
    end
end

-- returns true for yes or false for no
local function read_for_y_or_n(default_to)
    if default_to == nil then default_to = false end
    while true do
        local _, _, ret = string.find(io.read(), "%s-(.)")
        if not ret then
            return default_to
        elseif ret == "y" or ret == "Y" or ret == "yes" then
            return true
        elseif ret == "n" or ret == "N" or ret == "no" then
            return false
        else
            io.write(fmt("yo idk what '%s' means in this context ? \ntry again pls!\n", ret))
        end
    end
end

-- ==&== MAIN ==&==

local function main()
    io.write" welcome to tic tac toe! \n"
    io.write" ~~~~~~~~~~~~~~~~~~~~~~~ \n"

    local p1,p2
    local choose_letters = true
    local first_coord = true

    while true do --loop for repeat games
        if choose_letters then
            io.write"player 1 choose your letter!\n"
            p1 = read_for_letter()
            if p1 == "x" then
                p2 = "o"
            elseif p1 == "X" then
                p2 = "O"
            elseif p1 == "o" then
                p2 = "x"
            elseif p1 == "O" then
                p2 = "X"
            else
                while true do
                    io.write("player 2 choose your letter!\n")
                    p2 = read_for_letter()
                    if p2 ~= p1 then
                        break
                    else
                        io.write("ya can't pick the same letter as player 1......\n")
                    end
                end
            end
        end

        io.write(fmt("\nplayer 1 is %s's\nplayer 2 is %s's\n", p1, p2))
        io.write("lets play!\n\n")
        
        local board = new_board()
        local outcome = nil
        local p1s_turn = true
        local turns = 0
        while not outcome do
            -- turn
            io.write(fmt("%s pick a coordinate...\n", p1s_turn and "player 1" or "player 2"))
            if first_coord then
                io.write("*whisper* please format your coords as: over#[space]down#\n")
                first_coord = false
            end
            read_for_and_put_coord(board, p1s_turn and p1 or p2)
            p1s_turn = not p1s_turn
            turns = turns + 1

            -- print and chek
            print_board(board)
            outcome = check_board(board)
            if turns >= 9 then
                break
            end
        end

        io.write("\nfinissshhh...\n\n")

        if not outcome then
            io.write("dangg it was a draww..\n")
        else
            if outcome == p1 then
                io.write("o gr8 job player 1! real nice going..\n")
            else
                io.write("o gr8 job player 2! real nice going..\n")
            end
        end

        io.write("wanna play again, huh? [y,N]\n")
        if read_for_y_or_n(false) then
            io.write("gr88888888...\n")
            io.write("choose new letters? [y,N]\n")
            choose_letters = read_for_y_or_n(false)
        else
            io.write("thanks for playing!\n")
            break
        end
    end
end

main()