-- interest.lua (Deadlock problem fixed)

local BALANCE_INTEREST_RATE = tonumber(minetest.settings:get("bank_accounts.interest_rate_balance")) or 0.005
local CREDIT_INTEREST_RATE = tonumber(minetest.settings:get("bank_accounts.interest_rate_credit")) or 0.03
local INTEREST_CHECK_INTERVAL = tonumber(minetest.settings:get("bank_accounts.interest_check_interval")) or 600
local ONE_DAY_IN_SECONDS = 86400

local timestamp_file_path = minetest.get_worldpath() .. "/bank_interest_timestamp.txt"

local function read_timestamp()
    local f = io.open(timestamp_file_path, "r")
    if not f then return 0 end
    local time = tonumber(f:read("*a"))
    f:close()
    return time or 0
end

local function write_timestamp(time)
    local f = io.open(timestamp_file_path, "w")
    if not f then return end
    f:write(tostring(time))
    f:close()
end

local time_since_last_check = 0
bank_accounts.is_calculating_interest = false

minetest.register_globalstep(function(dtime)
    if not minetest.settings:get_bool("bank_accounts.interest_enabled", true) then
        return
    end
    
    time_since_last_check = time_since_last_check + dtime
    if time_since_last_check < INTEREST_CHECK_INTERVAL then
        return
    end
    time_since_last_check = 0
    
    local last_timestamp = read_timestamp()
    
    if os.time() - last_timestamp >= ONE_DAY_IN_SECONDS then
        if bank_accounts.is_calculating_interest then
            return
        end
        
        minetest.log("action", "[bank_accounts] Starting daily interest calculation...")
        bank_accounts.is_calculating_interest = true

        local data = bank_accounts.get_all_data()
        local changes_made = false
        
        -- Calculate interest on positive balances
        if BALANCE_INTEREST_RATE > 0 then
            for player_name, balance in pairs(data.balance) do
                if balance > 0 then
                    local interest = balance * BALANCE_INTEREST_RATE
                    data.balance[player_name] = balance + interest
                    if not data.history then data.history = {} end
                    if not data.history[player_name] then data.history[player_name] = {} end
                    table.insert(data.history[player_name], 1, {
                        timestamp = os.time(), type = "Interest Paid", account = "balance",
                        amount = interest, new_total = data.balance[player_name],
                        purpose = S("Daily interest (@1%)", BALANCE_INTEREST_RATE * 100), other = "Bank"
                    })
                    changes_made = true
                end
            end
        end

        -- Calculate interest on credit debt
        if CREDIT_INTEREST_RATE > 0 then
            for player_name, credit in pairs(data.credit) do
                if credit > 0 then
                    local interest = credit * CREDIT_INTEREST_RATE
                    data.credit[player_name] = credit + interest
                    if not data.history then data.history = {} end
                    if not data.history[player_name] then data.history[player_name] = {} end
                    table.insert(data.history[player_name], 1, {
                        timestamp = os.time(), type = "Interest Charged", account = "credit",
                        amount = interest, new_total = data.credit[player_name],
                        purpose = S("Daily interest (@1%)", CREDIT_INTEREST_RATE * 100), other = "Bank"
                    })
                    changes_made = true
                end
            end
        end

        if changes_made then
            -- CORRECTED: Now calls the API function that bypasses the lock
            local success = bank_accounts.save_all(data)
            if success then
                minetest.log("action", "[bank_accounts] Daily interest calculation complete and saved.")
                -- CORRECTED: Timestamp is only updated after a successful save.
                write_timestamp(os.time())
            else
                 minetest.log("error", "[bank_accounts] Saving interest data FAILED. Will retry later.")
            end
        else
            -- If no changes were made, still update the timestamp to prevent re-running immediately.
             write_timestamp(os.time())
        end
        
        bank_accounts.is_calculating_interest = false
    end
end)