local healthRechargeTime = CreateConVar(
    "gc_healthchargerrechargetime",
    "60",
    FCVAR_ARCHIVE,
    "Seconds before an emptied wall health charger refills; 0 disables automatic refills"
)

local suitRechargeTime = CreateConVar(
    "gc_suitchargerrechargetime",
    "30",
    FCVAR_ARCHIVE,
    "Seconds before an emptied wall suit charger refills; 0 disables automatic refills"
)

local chargerClasses = {
    item_healthcharger = healthRechargeTime,
    item_suitcharger = suitRechargeTime
}

local chargerStates = {}

local function GetChargerJuice(charger)
    local juice = charger:GetInternalVariable("m_iJuice")
    return tonumber(juice)
end

local function GetChargerCapacity(charger, juice)
    local maxJuice = charger:GetInternalVariable("m_iMaxJuice")
    local displayedJuice = charger:GetInternalVariable("m_flJuice")

    return math.max(
        juice or 0,
        tonumber(maxJuice) or 0,
        tonumber(displayedJuice) or 0
    )
end

local function RefillCharger(charger, state)
    charger:Fire("Recharge")

    -- GMod's suit charger implements Recharge, but item_healthcharger does not
    -- on all engine branches. Give the native input a frame to run, then use
    -- its internal Source charge fields as a compatibility fallback.
    timer.Simple(0.1, function()
        if not IsValid(charger) or (GetChargerJuice(charger) or 0) > 0 then return end
        if not state.capacity or state.capacity <= 0 then return end

        charger:SetSaveValue("m_iJuice", state.capacity)
        if charger:GetInternalVariable("m_flJuice") ~= nil then
            charger:SetSaveValue("m_flJuice", state.capacity)
        end
        charger:SetCycle(0)
        charger:EmitSound("items/medshot4.wav", 60, 100, 0.5)
    end)
end

timer.Create("CustomCoopRechargeWallChargers", 1, 0, function()
    local now = CurTime()
    local seen = {}

    for className, rechargeTime in pairs(chargerClasses) do
        local delay = math.max(rechargeTime:GetFloat(), 0)

        for _, charger in ipairs(ents.FindByClass(className)) do
            seen[charger] = true

            local juice = GetChargerJuice(charger)
            if juice == nil then continue end

            local state = chargerStates[charger]
            if not state then
                -- A mapper may deliberately place a charger with zero charge.
                -- Only chargers observed being drained during play are refilled.
                state = {
                    lastJuice = juice,
                    capacity = GetChargerCapacity(charger, juice)
                }
                chargerStates[charger] = state
            elseif juice > 0 or delay == 0 then
                state.refillAt = nil
            elseif state.lastJuice > 0 and juice <= 0 then
                state.refillAt = now + delay
            elseif state.refillAt and now >= state.refillAt then
                -- Use the native Source input rather than replacing the entity,
                -- preserving its name, Hammer I/O, animation and sounds.
                RefillCharger(charger, state)
                state.refillAt = nil
            end

            state.lastJuice = juice
        end
    end

    for charger in pairs(chargerStates) do
        if not seen[charger] or not IsValid(charger) then
            chargerStates[charger] = nil
        end
    end
end)

hook.Add("PostCleanupMap", "CustomCoopResetWallChargerTracking", function()
    chargerStates = {}
end)