require("entry/mac_popup")

CampaignMenu = {}
CampaignMenu.__index = CampaignMenu

local S = tex.get_screen_scale()
local FADE_MS = 250
local WAIT_MS = 1500
local SELECT_MS = 30000
local SLIDE_MS = 150
local OUT_MS, IN_MS = 167, 150
local ARROW_MS, ARROW_DX, ARROW_GAP = 1000, 30 * S, 600 * S
-- small panel left edge by slot offset; the centre slot sits under the big panel
local SLOT_X = { [-2] = -338, [-1] = 17, [0] = 482, [1] = 947, [2] = 1302 }
local SLOT_STEP, SLOT_Y = 355, 262 * S
local LEFT, RIGHT, DECIDE = 1, 2, 3

local function clamp01(v) return math.max(0.0, math.min(1.0, v)) end

local function slot_x(offset)
    local lo = math.floor(offset)
    local function at(k)
        if k < -2 then return SLOT_X[-2] + (k + 2) * SLOT_STEP end
        if k > 2 then return SLOT_X[2] + (k - 2) * SLOT_STEP end
        return SLOT_X[k]
    end
    return (at(lo) + (at(lo + 1) - at(lo)) * (offset - lo)) * S
end

function CampaignMenu.new(ids)
    for _, id in ipairs(ids) do
        if id == "mac" then return MacPopup.new() end
    end
    local self = setmetatable({}, CampaignMenu)
    self.ids = { "skip" }
    for _, id in ipairs(ids) do self.ids[#self.ids + 1] = id end
    self.small, self.main = {}, {}
    for _, id in ipairs(self.ids) do
        self.small[id] = tex.get_texture("entry/campaign/" .. id .. "_small")
        self.main[id] = tex.get_texture("entry/campaign/" .. id .. "_main")
    end
    self.arrow = tex.get_texture("entry/campaign/arrow")
    self.current = 1
    self.t0 = tex.get_current_ms()
    self.now = self.t0
    self.turn = nil
    self.decided = nil
    if audio.has_sound("campaign_entry") then audio.play_sound("campaign_entry", "sound") end
    return self
end

function CampaignMenu:update(current_ms)
    self.now = current_ms
    if not self.decided and current_ms - self.t0 >= WAIT_MS + SELECT_MS then
        self:decide()
    end
    if self.turn and current_ms - self.turn.t0 >= OUT_MS + IN_MS then
        self.turn = nil
    end
end

function CampaignMenu:decide()
    self.decided = self.now
end

function CampaignMenu:input(action)
    if self.decided or self.turn or self.now - self.t0 < WAIT_MS then
        return false
    end
    if action == DECIDE then
        self:decide()
        return true
    end
    local dir = action == RIGHT and 1 or -1
    self.turn = { dir = dir, t0 = self.now, from = self.current }
    self.current = (self.current - 1 + dir) % #self.ids + 1
    return true
end

function CampaignMenu:is_done()
    return self.decided ~= nil and self.now - self.decided >= FADE_MS
end

function CampaignMenu:get_choice()
    return self.ids[self.current]
end

function CampaignMenu:draw()
    local fade = clamp01((self.now - self.t0) / FADE_MS)
    if self.decided then fade = 1 - clamp01((self.now - self.decided) / FADE_MS) end
    local n = #self.ids

    -- mid-turn every slot is still `dir` slots short of where it lands
    local shift = 0
    if self.turn then shift = self.turn.dir * (1 - clamp01((self.now - self.turn.t0) / SLIDE_MS)) end
    for k = -3, 3 do
        local offset = k + shift
        if offset > -3 and offset < 3 then
            local id = self.ids[(self.current - 1 + k) % n + 1]
            tex.draw_texture(self.small[id], { x = slot_x(offset), y = SLOT_Y,
                                               fade = fade * clamp01(math.abs(offset)) })
        end
    end

    local id, main_fade = self.ids[self.current], 1
    if self.turn then
        local el = self.now - self.turn.t0
        if el < OUT_MS then
            id, main_fade = self.ids[self.turn.from], 1 - el / OUT_MS
        else
            main_fade = clamp01((el - OUT_MS) / IN_MS)
        end
    end
    tex.draw_texture(self.main[id], { fade = fade * main_fade })

    local el = self.now - self.t0 - WAIT_MS
    if el >= 0 and not self.decided then
        local u = (el % ARROW_MS) / ARROW_MS
        tex.draw_texture(self.arrow, { x = -ARROW_DX * u, fade = fade * (1 - u) })
        tex.draw_texture(self.arrow, { x = ARROW_GAP + ARROW_DX * u, fade = fade * (1 - u), mirror = "horizontal" })
    end
end