-- SongSelectState constants (must match enums.h)
local STATE_BROWSING      = 0
local STATE_SONG_SELECTED = 1
local STATE_DIFF_SORTING  = 2
local STATE_SEARCHING     = 3
local STATE_DAN_SELECTED  = 4

SongSelect = {}
SongSelect.__index = SongSelect

function SongSelect.new()
    local self = setmetatable({}, SongSelect)
    tex.load_animations("song_select")
    tex.load_folder("song_select", "global")

    -- Animations (IDs from song_select/animation.json)
    self.text_fade_in    = tex.get_animation(4)   -- fade in/out the top-left label text
    self.blue_arrow_fade = tex.get_animation(29)  -- blue arrow opacity pulse
    self.blue_arrow_move = tex.get_animation(30)  -- blue arrow horizontal drift

    self.blue_arrow_fade:start()
    self.blue_arrow_move:start()
    self.text_fade_in:start()

    -- Cached texture IDs
    self._id_footer            = tex.get_id("global", "footer")            or 0
    self._id_arrow             = tex.get_id("global", "arrow")             or 0
    self._id_song_num_bg       = tex.get_id("global", "song_num_bg")       or 0
    self._id_song_select       = tex.get_id("global", "song_select")       or 0
    self._id_difficulty_select = tex.get_id("global", "difficulty_select") or 0

    return self
end

function SongSelect:update(current_ms)
    self.text_fade_in:update(current_ms)
    self.blue_arrow_fade:update(current_ms)
    self.blue_arrow_move:update(current_ms)
end

-- Call whenever the screen state changes so the label cross-fades correctly.
function SongSelect:restart_text_fade()
    self.text_fade_in:start()
end

function SongSelect:draw_footer()
    tex.draw_id(self._id_footer)
end

-- Draw the navigation arrows and the top-left state label.
-- state: one of the STATE_* constants above (passed from C++ as an int).
function SongSelect:draw_overlays(state)
    -- Blue navigation arrows are only shown while browsing.
    if state == STATE_BROWSING then
        local drift = self.blue_arrow_move.attribute * 2
        local fade  = self.blue_arrow_fade.attribute
        tex.draw_id(self._id_arrow, { x = -drift,             fade = fade, index = 0 })
        tex.draw_id(self._id_arrow, { mirror = "horizontal",
                                      x =  drift,             fade = fade, index = 1 })
    end

    -- Top-left label: cross-fade between "SONG SELECT" and "DIFFICULTY SELECT".
    local label_fade = self.text_fade_in.attribute
    if state == STATE_SONG_SELECTED then
        tex.draw_id(self._id_difficulty_select, { fade = label_fade })
        tex.draw_id(self._id_song_select,       { fade = 1 - label_fade })
    else
        tex.draw_id(self._id_difficulty_select, { fade = 1 - label_fade })
        tex.draw_id(self._id_song_select,       { fade = label_fade })
    end
end