local PUSH_MS = 15000

local appOpen = false

local function cfg()
    local weather = Config and Config.Weather or nil
    if not weather or weather.Enable == false then return nil end
    return weather
end

local function zoneName(coords)
    local ok, label = pcall(function()
        return GetLabelText(GetNameOfZone(coords.x, coords.y, coords.z))
    end)

    if ok and label and label ~= "NULL" and label ~= "" then return label end
    return nil
end

local function isNight(c, hour)
    local from = tonumber(c.NightStart) or 21
    local to = tonumber(c.NightEnd) or 6

    if from == to then return false end
    if from < to then return hour >= from and hour < to end
    return hour >= from or hour < to
end

local function nameOf(c, value)
    if type(value) == "string" then return value end

    for key in pairs(c.Temps or {}) do
        if GetHashKey(key) == value then return key end
    end
    return "NEUTRAL"
end

local function baseTemp(c, type_)
    return tonumber((c.Temps or {})[type_]) or tonumber((c.Temps or {})["NEUTRAL"]) or 22
end

--- Celsius in, whatever the server asked for out.
local function toUnit(c, celsius)
    if c.Celsius == false then return celsius * 9 / 5 + 32 end
    return celsius
end

local function rounded(value)
    return math.floor(value + 0.5)
end

---------------------------------------------------------------------------------
-- Invented forecast
---------------------------------------------------------------------------------

local function rng(seed)
    local state = seed % 2147483647
    if state <= 0 then state = state + 2147483646 end

    return function(n)
        state = (state * 16807) % 2147483647
        return (state % n) + 1
    end
end

local FORECAST_POOL = {
    "EXTRASUNNY", "CLEAR", "CLEAR", "CLOUDS", "CLOUDS",
    "CLEARING", "OVERCAST", "SMOG", "FOGGY", "RAIN", "THUNDER"
}

--- @param c table Config.Weather
--- @param days number
--- @param seed number stable per in-game day
local function dailyForecast(c, days, seed)
    if days <= 0 then return {} end

    local next_ = rng(seed)
    local out = {}

    for i = 1, days do
        local type_ = FORECAST_POOL[next_(#FORECAST_POOL)]
        local base = baseTemp(c, type_)

        local drift = next_(7) - 4
        local high = base + drift
        local low = high + (tonumber(c.NightOffset) or -6) - next_(3)

        out[#out + 1] = {
            offset = i - 1,
            weather = type_,
            high = rounded(toUnit(c, high)),
            low = rounded(toUnit(c, low)),
        }
    end

    return out
end

local function hourlyForecast(c, hours, seed, hour, current, upcoming)
    if hours <= 0 then return {} end

    local next_ = rng(seed + 7919)
    local out = {}

    for i = 1, hours do
        local at = (hour + i - 1) % 24
        local type_

        if i == 1 then
            type_ = current
        elseif i == 2 then
            type_ = upcoming
        else
            type_ = FORECAST_POOL[next_(#FORECAST_POOL)]
        end

        local celsius = baseTemp(c, type_)
        if isNight(c, at) then
            celsius = celsius + (tonumber(c.NightOffset) or 0)
        end

        out[#out + 1] = {
            hour = at,
            weather = type_,
            temperature = rounded(toUnit(c, celsius)),
            real = i <= 2,
        }
    end

    return out
end

---------------------------------------------------------------------------------

--- @return table|nil snapshot for the UI
function WeatherSnapshot()
    local c = cfg()
    if not c then return nil end

    local current = nameOf(c, GetPrevWeatherTypeHashName())
    local upcoming = nameOf(c, GetNextWeatherTypeHashName())

    local hour = GetClockHours()
    local minute = GetClockMinutes()
    local night = isNight(c, hour)

    local celsius = baseTemp(c, current)
    if night then celsius = celsius + (tonumber(c.NightOffset) or 0) end

    local seed = (tonumber(c.ForecastSeed) or 1)
        + GetClockDayOfMonth() * 31
        + (GetClockMonth() + 1) * 372
        + GetClockYear() * 4464

    local coords = GetEntityCoords(PlayerPedId())

    return {
        weather = current,
        next = upcoming,
        temperature = rounded(toUnit(c, celsius)),
        unit = c.Celsius == false and "F" or "C",
        hour = hour,
        minute = minute,
        night = night,
        zone = zoneName(coords),
        raining = GetRainLevel() > 0.0,
        rainLevel = math.floor(GetRainLevel() * 100 + 0.5) / 100,
        windSpeed = math.floor(GetWindSpeed() * 10 + 0.5) / 10,
        sunrise = tonumber(c.NightEnd) or 6,
        sunset = tonumber(c.NightStart) or 21,
        hourly = hourlyForecast(c, tonumber(c.HourlyHours) or 12, seed, hour, current, upcoming),
        daily = dailyForecast(c, tonumber(c.ForecastDays) or 10, seed),
    }
end

local function push()
    local snapshot = WeatherSnapshot()
    if not snapshot then return end

    SendNUIMessage({ action = "weatherData", weather = snapshot })
end

function GetWeatherConfig()
    local c = cfg()
    if not c then return { enabled = false } end

    return {
        enabled = true,
        celsius = c.Celsius ~= false,
        forecastDays = tonumber(c.ForecastDays) or 10,
        hourlyHours = tonumber(c.HourlyHours) or 12,
    }
end

exports("GetWeatherConfig", GetWeatherConfig)

RegisterNUICallback("weatherRequest", function(_, cb)
    appOpen = true
    push()
    cb("ok")
end)

RegisterNUICallback("weatherClosed", function(_, cb)
    appOpen = false
    cb("ok")
end)

CreateThread(function()
    if not cfg() then return end

    while true do
        Wait(PUSH_MS)
        if appOpen then push() end
    end
end)

exports("GetWeather", WeatherSnapshot)