--[[
List of actions, by order of priority:
    - Complete a 3 dice combo 4-6
    - Cancel a 3 dice combo 4-6
    - Complete a 3 dice combo 1-3
    - Complete a 2 dice combo 4-6
    - Cancel a 3 dice combo 1-3
    - Complete a 2 dice combo 1-3
    - Cancel a 2 dice combo 4-6
    - Cancel a 2 dice combo 1-3

    - Look at the column's sum before removing a die.
        It if is <=15, try to keep it as is, unless you're removing a 6 (or a 5)
]]
---Returns the column indexes (1-based) with completable combos
---@param dice table The 2d table with dice values
---@param value integer The dice value to place
---@param len 2|3 The possible combo length
---@return table The columns list (1-based)
function get_combos_to_complete(dice, value, len)
    local ids = {}
    for col = 1, 3 do
        if table.count(dice[col], 0) >= 1
            and table.count(dice[col], value) == len - 1 then
            table.insert(ids, col)
        end
    end

    return ids
end

---@param mine table "My" 2d table with dice values
---@param other table The "other" (opponent) 2d table with dice values
---@param value integer The dice value to place
---@param len 2|3 The possible combo length
---@return table The columns list (1-based)
function get_combos_to_cancel(mine, other, value, len)
    local ids = {}
    for col = 1, 3 do
        if table.count(mine[col], 0) >= 1
            and table.count(other[col], value) == len - 1 then
            table.insert(ids, col)
        end
    end

    return ids
end

function get_most_empty_cols(dice)
    local ids = {}

    for z = 3, 1, -1 do
        for col = 1, 3 do
            if table.count(dice[col], 0) == z then
                table.insert(ids, col)
            end
        end
        if #ids > 0 then return ids end
    end
end

---Place the die in the best possible column
---@param mine table The 2d table of "my" dice
---@param other any The 2d table of the "other" dice
---@param die integer The die to place
---@return integer # The column where to place the die
function ai_pick_column(mine, other, die)
    trace("--")
    trace("AI")
    trace("--")

    if die >= 4 then
        --#region Complete a 3 combo 4-5-6
        local combos = get_combos_to_complete(mine, die, 3)
        if #combos > 0 then
            trace("Making a 3 combo with " .. die)
            return math.randomitem(combos)
        end
        --#endregion Complete a 3 combo 4-5-6

        -- #region Cancel a 3-dice combo 4-5-6
        combos = get_combos_to_cancel(mine, other, die, 3)
        if #combos > 0 then
            trace("Cancelling a 3 combo with " .. die)
            return math.randomitem(combos)
        end
        --#endregion Cancel a 3-dice combo 4-5-6

        -- #region Complete a 2 combo 4-5-6
        combos = get_combos_to_complete(mine, die, 2)
        if #combos > 0 then
            trace("Making a 2 combo with " .. die)
            return math.randomitem(combos)
        end
        -- #endregion Complete a 2 combo 4-5-6
    end


    -- #region Complete a 3 combo 1-2-3
    combos = get_combos_to_complete(mine, die, 3)
    if #combos > 0 then
        trace("Making a 3 combo with " .. die)
        return math.randomitem(combos)
    end
    -- #endregion Complete a 3 combo 1-2-3

    -- #region Complete a 2 combo 1-2-3
    combos = get_combos_to_complete(mine, die, 2)
    if #combos > 0 then
        trace("Making a 2 combo with " .. die)
        return math.randomitem(combos)
    end
    -- #endregion Complete a 2 combo 1-2-3

    -- #region Random column

    -- TODO: if 5-6, attack the opponent.
    -- TODO: else, chose the column with the lowest sum
    -- TODO: it's best to AVOID attacking the opponent when his sum is <= 15
    -- TODO: it's best to avoid canceling 1-2 values

    trace("Placing " .. die .. " at random")
    return math.randomitem(get_most_empty_cols(mine))
    -- #endregion Random column
end