local M = {}

local focusCanvas = nil
local activeProfile = nil
local configPath = hs.configdir .. "/focus_profiles.json"

local function loadProfiles()
    local file = io.open(configPath, "r")
    if not file then
        print("Error: Could not open focus_profiles.json")
        return nil
    end
    local content = file:read("*a")
    file:close()
    return hs.json.decode(content)
end

local function manageApps(profileConfig)
    for _, appName in ipairs(profileConfig.close) do
        local app = hs.application.get(appName)
        if app then app:kill() end
    end

    for _, appName in ipairs(profileConfig.keepOpen) do
        hs.application.launchOrFocus(appName)
    end
end

local function setFocusOverlay(alpha)
    if focusCanvas then
        focusCanvas:delete()
        focusCanvas = nil
    end

    if not alpha or alpha == 0 then return end

    local mainScreen = hs.screen.mainScreen()
    local rect = mainScreen:frame()

    focusCanvas = hs.canvas.new(rect)
    focusCanvas:insertElement({
        action = "fill",
        type = "rectangle",
        fillColor = { red = 0, green = 0, blue = 0, alpha = alpha }
    })
    
    focusCanvas:level(50) 
    focusCanvas:show()
    
    local frontApp = hs.application.frontmostApplication()
    if frontApp then
        local win = frontApp:mainWindow()
        if win then win:focus() end
    end
end

function M.activate(profileName)
    local profiles = loadProfiles()
    if not profiles or not profiles[profileName] then
        print("Error: Profile '" .. tostring(profileName) .. "' not found.")
        return "Profile not found"
    end

    activeProfile = profileName
    local currentProfileConfig = profiles[profileName]

    manageApps(currentProfileConfig)
    setFocusOverlay(currentProfileConfig.dimAlpha)
    
    return "Activated " .. profileName .. " mode"
end

function M.clear()
    setFocusOverlay(nil)
    activeProfile = nil
    return "Focus mode cleared"
end

hs.screen.watcher.new(function()
    if activeProfile then
        local profiles = loadProfiles()
        if profiles and profiles[activeProfile] then
            setFocusOverlay(profiles[activeProfile].dimAlpha)
        end
    end
end):start()

return M