local SparkleDonBG     = require("background/bg_objects/donbg/sparkle")
local Fever            = require("background/bg_objects/fever")
local Footer           = require("background/bg_objects/footer")
local Dancer           = require("background/bg_objects/dancer")
local RendaController  = require("background/bg_objects/renda")
local ChibiController  = require("background/bg_objects/chibi")
local BaseChibi        = require("background/bg_objects/chibi/base")
local ChibiWave        = require("background/bg_objects/chibi/wave")
local Timing           = require("background/bg_objects/timing")

-- THE IDOLM@STER SideM
local COLLAB_PATH      = "background/collab/imas_sidem"
local MAX_DANCERS      = 3

-- Don band: the base scrolls one tile left every 5.33s; the clear set scrolls with it under a
-- glow strip that pulses every second, and stars twinkle in clusters over it (still, not
-- scrolling). Ambient, in ms.
local SIDEM_DONBG = {
    layers = {
        { key = "background", ms = 5333 },
        { key = "glow", clear_only = true, tile = 0, alpha = 0.148,
          period = 1000, pulse = { { 500, -1000 }, { 500, 1000, "out" } } },
    },
}

-- star sizes for SparkleDonBG's clusters: { pop, life, x, y, from, to } in Lumen frames
local SIDEM_STARS = {
    trio = {
        { 110, 34, 0, 0, 0.7, 1.3 }, { 45, 34, 0, 0, 0.7, 1.3 },
        { 106, 20, 50, -100, 0.5, 1 }, { 31, 20, 50, -100, 0.5, 1 },
        { 10, 20, 300, 0, 0.31, 1.09 }, { 50, 20, 300, 0, 0.43, 1.05 }, { 85, 19, 300, 0, 0.26, 1 },
    },
    pair = {
        { 11, 34, 0, 0, 0.68, 1.26 }, { 68, 34, 0, 0, 0.68, 1.26 },
        { 0, 19, 300, 0, 0.86, 1.04 }, { 38, 20, 50, -100, 0.5, 1 },
        { 64, 20, 300, 0, 0.65, 0.9 }, { 94, 20, 50, -100, 0.5, 1 },
    },
}

-- Stage: two halves of a rig around a screen cycling the 315 Production logo and three units
-- (3 beats each), under a pair of white spotlights. Timed in beats.
local SCREEN_BEATS, SCREENS = 3, 4

local SidemBGNormal   = {}
SidemBGNormal.__index = SidemBGNormal

function SidemBGNormal.new(bpm)
    local self = setmetatable({}, SidemBGNormal)
    self.name = "bg_0"
    tex.load_folder(COLLAB_PATH, "bg_normal/" .. self.name)
    local function id(key) return tex.get_texture(COLLAB_PATH .. "/" .. self.name .. "/" .. key) or 0 end
    self._id_bg      = id("background")
    self._id_screen  = id("screen")
    self._id_overlay = id("overlay")
    self.beat        = 60000 / bpm
    self.t           = 0
    return self
end

function SidemBGNormal:update(current_time_ms, bpm)
    if bpm then self.beat = 60000 / bpm end
    self.t = self.t + (current_time_ms - (self.last_ms or current_time_ms)) / self.beat
    self.last_ms = current_time_ms
end

-- the two spotlights (also drawn brighter by the clear stage)
function SidemBGNormal:draw_spots(fade)
    tex.draw_texture(self._id_overlay, { index = 0, fade = fade })
    tex.draw_texture(self._id_overlay, { index = 1, fade = fade, mirror = "horizontal" })
end

function SidemBGNormal:draw()
    tex.draw_texture(self._id_bg, { index = 0 })
    tex.draw_texture(self._id_bg, { index = 1, mirror = "horizontal" })
    tex.draw_texture(self._id_screen, { frame = math.floor(self.t / SCREEN_BEATS) % SCREENS })
    self:draw_spots(0.5)
end

function SidemBGNormal:destroy() tex.unload_folder(COLLAB_PATH, "bg_normal/" .. self.name) end

-- Clear stage: over the normal one, cyan spotlights and brighter white ones fade in over a beat
-- while green lasers fan down from three points above the stage. Each point shows six of
-- twelve rays (35..145 degrees, 10 apart), a new set every 0.375 beat in a 1.5-beat cycle.
-- Losing clear cuts the lasers and fades the lights out over a beat. Timed in beats.
local FEVER_FADE   = 1
local SPOT_ALPHA   = 0.648
local WHITE_ALPHA  = 0.352
local LASER_ALPHA  = 0.488
local LASER_STEP   = 0.375
local LASER_SETS   = {
    { 35, 45, 75, 85, 115, 125 },
    { 45, 55, 85, 105, 115, 145 },
    { 55, 65, 95, 105, 135, 145 },
    { 35, 65, 75, 95, 125, 135 },
}
local LASER_ORIGINS = { -7.5, 632.5, 1272.5 }
local LASER_Y       = 271.3
local LASER_PIVOT   = 16 -- the ray's centre line in its image

local SidemBGFever   = {}
SidemBGFever.__index = SidemBGFever

function SidemBGFever.new(bpm)
    local self = setmetatable({}, SidemBGFever)
    self.name = "bg_fever_0"
    tex.load_folder(COLLAB_PATH, "bg_fever/" .. self.name)
    local function id(key) return tex.get_texture(COLLAB_PATH .. "/" .. self.name .. "/" .. key) or 0 end
    self._id_spotlight = id("spotlight")
    self._id_laser     = id("laser")
    self.beat          = 60000 / bpm
    self.state         = nil -- nil (hidden), "in", "out"
    self.level         = 0   -- 0..1 of the lights
    return self
end

function SidemBGFever:start() self.state, self.t, self.from = "in", 0, self.level end

function SidemBGFever:stop()
    if self.state ~= "in" then return end
    self.state, self.t, self.from = "out", 0, self.level
end

function SidemBGFever:update(current_time_ms, bpm)
    if bpm then self.beat = 60000 / bpm end
    local dt = (current_time_ms - (self.last_ms or current_time_ms)) / self.beat
    self.last_ms = current_time_ms
    if not self.state then return end
    self.t = self.t + dt
    local k = math.min(1, self.t / FEVER_FADE)
    if self.state == "in" then
        self.level = self.from + (1 - self.from) * k
    else
        self.level = self.from * (1 - k)
        if k >= 1 then self.state = nil end
    end
end

function SidemBGFever:draw(bg_normal)
    if not self.state then return end
    local lv = self.level
    tex.draw_texture(self._id_spotlight, { index = 0, fade = SPOT_ALPHA * lv })
    tex.draw_texture(self._id_spotlight, { index = 1, fade = SPOT_ALPHA * lv, mirror = "horizontal" })
    bg_normal:draw_spots(WHITE_ALPHA * lv)
    if self.state ~= "in" then return end
    local set = LASER_SETS[math.floor(self.t / LASER_STEP) % #LASER_SETS + 1]
    for _, x in ipairs(LASER_ORIGINS) do
        for _, angle in ipairs(set) do
            tex.draw_texture(self._id_laser, { x = x, y = LASER_Y, origin = { 0, LASER_PIVOT }, rotation = angle,
                                               fade = LASER_ALPHA })
        end
    end
end

function SidemBGFever:destroy() tex.unload_folder(COLLAB_PATH, "bg_fever/" .. self.name) end

-- Line-up: jumps up, bounces 50px a beat swapping poses
local SIDEM_FEVER = { rise = 210, bounce = 50, drop = 380, poses = true }

-- Drumroll: notes fly up and to the right, the default renda_c flight
local RENDA = { ms = { 2000 }, dx = 1560, dy = -1648, x_range = 500, y_range = 20 }

-- Dancers: all three jump up from below, land with a squash, dance a 4-beat routine (two
-- 2-beat phrases: a half-beat pose, two 0.375s and three quarters) and squash, hop and drop
-- away when removed. Timed in beats; poses are offsets of Lumen's dancer origin (y 670), which
-- sits 312px down the images and is the pivot for the squash, so the feet stay put.
local SIDEM_DANCERS = Dancer.define({ default = {
    origin = { 120, 312 },
    enter  = {
        beats = 2,
        { 0,     0, 0, 312, to = { 0, -48, "out" } }, -- jumps up from below
        { 0.675, 0, 0, -48, to = { 0, 0, "in" } },
        { 0.925, 0, 0, 0, to = { nil, nil, nil, sx = 1.03, sy = 0.95 } }, -- lands with a squash
        { 1.025, 0, 0, 0, sx = 1.02, sy = 0.97, to = { nil, nil, nil, sx = 1, sy = 1 } },
        { 1.1,   0, 0, 0 },
    },
    dance  = Timing.steps({
        { 0, 0.5, x = 0, y = 0 }, { 1, 0.375 }, { 2, 0.375 }, { 3, 0.25 }, { 4, 0.25 }, { 5, 0.25 },
        { 6, 0.5 }, { 7, 0.375 }, { 8, 0.375 }, { 9, 0.25 }, { 10, 0.25 }, { 11, 0.25 },
    }),
    leave  = {
        beats = 1.45,
        { 0,     0, 0, 0, to = { nil, nil, nil, sy = 0.95 } },
        { 0.125, 0, 0, 0, sy = 0.96, to = { 0, -40, "out", sy = 1 } }, -- hops up and drops away
        { 0.475, 0, 0, -40, to = { 0, 382, "in" } },
    },
} })

-- Slots (left, centre, right) from Lumen's dancer positions; centre on top
local DANCER_CENTERS    = { 427, 640, 853 }
local DANCER_DRAW_ORDER = { 3, 1, 2 }
local DANCER_SPAWN      = { 1, 0, 2 } -- 0-indexed slots in join order: centre, left, right
-- dancer index by join order: dancer1 (centre), dancer2 (left), dancer3 (right)
local DANCER_JOIN_ORDER = { 2, 1, 0 }

-- Chibis for good hits: an energy drink or an AP bar hops in growing from 70% size, then bobs
-- across the don band in a zig-zag. They run 20px left of BaseChibi's run, which texture.json
-- takes (x 540, not 560), so the hop starts 20px right of Lumen's.
local SIDEM_CHIBIS = {}
for key = 0, 1 do
    SIDEM_CHIBIS[key + 1] = {
        key  = tostring(key),
        hop  = { from = { -408, 13 }, peak = { -338, -36 }, up = 0.25 },
        run  = { y = 8 },
        wave = { first = -32, height = 32, beats = 0.45 },
    }
end

-- Background

local ImasSidemBackground = {}
ImasSidemBackground.__index = ImasSidemBackground

function ImasSidemBackground.new(player_num, bpm)
    local self          = setmetatable({}, ImasSidemBackground)
    self.donbg          = SparkleDonBG.new(player_num, COLLAB_PATH, SIDEM_DONBG, SIDEM_STARS)
    self.bg_normal      = SidemBGNormal.new(bpm)
    self.bg_fever       = SidemBGFever.new(bpm)
    self.footer         = Footer.new(COLLAB_PATH, 0, { false, true })
    self.fever          = Fever.new(bpm, COLLAB_PATH, SIDEM_FEVER)
    self.dancer         = Dancer.BaseDancerGroup.new(0, bpm, MAX_DANCERS, COLLAB_PATH, SIDEM_DANCERS)
    self.dancer.spawn_positions = DANCER_SPAWN
    local by_index = {}
    for _, d in ipairs(self.dancer.dancers) do by_index[d.index] = d end
    for i, index in ipairs(DANCER_JOIN_ORDER) do self.dancer.dancers[i] = by_index[index] end
    self.renda          = RendaController.new(COLLAB_PATH, 0, RENDA)
    self.chibi          = ChibiController.new(bpm, COLLAB_PATH, 0)
    self.is_clear       = false
    self.is_rainbow     = false
    self.last_milestone = 1
    return self
end

function ImasSidemBackground:update(current_ms, bpm)
    self.donbg:update(current_ms, bpm)
    self.bg_normal:update(current_ms, bpm)
    self.bg_fever:update(current_ms, bpm)
    self.fever:update(current_ms, bpm)
    self.dancer:update(current_ms, bpm)
    self.renda:update(current_ms)
    self.chibi:update(current_ms, bpm)
end

function ImasSidemBackground:add_chibi(player_num)
    BaseChibi.add(self.chibi, SIDEM_CHIBIS[math.random(#SIDEM_CHIBIS)], COLLAB_PATH, player_num, ChibiWave, "chibi_0")
end

function ImasSidemBackground:handle_good(player_num) self:add_chibi(player_num) end

function ImasSidemBackground:handle_ok(player_num) self:add_chibi(player_num) end

function ImasSidemBackground:handle_bad(player_num) self.chibi:add_chibi(player_num, true) end

function ImasSidemBackground:handle_drumroll(player_num) self.renda:add_renda() end

function ImasSidemBackground:handle_balloon(player_num) self.renda:add_renda() end

function ImasSidemBackground:handle_gauge(player_num, progress, is_clear, is_rainbow)
    self.donbg:set_clear(is_clear)
    if is_clear and not self.is_clear then self.bg_fever:start() end
    if not is_clear and self.is_clear then self.bg_fever:stop() end
    if is_rainbow and not self.is_rainbow then self.fever:start() end
    if not is_rainbow and self.is_rainbow then self.fever:stop() end
    self.is_clear   = is_clear
    self.is_rainbow = is_rainbow

    local current_milestone
    if is_clear then
        current_milestone = MAX_DANCERS
    else
        current_milestone = math.min(MAX_DANCERS - 1, math.floor(progress * MAX_DANCERS))
    end
    if current_milestone > self.last_milestone then
        for _ = 1, current_milestone - self.last_milestone do self.dancer:add_dancer() end
        self.last_milestone = current_milestone
    elseif current_milestone < self.last_milestone then
        for _ = 1, self.last_milestone - current_milestone do self.dancer:leave_dancer() end
        self.last_milestone = current_milestone
    end
end

function ImasSidemBackground:draw_back()
    self.bg_normal:draw()
    self.bg_fever:draw(self.bg_normal)
    self.footer:draw()
    self.donbg:draw()
    self.renda:draw()
    self.dancer:draw_slots(DANCER_CENTERS, DANCER_DRAW_ORDER)
    self.fever:draw()
    self.chibi:draw()
end

function ImasSidemBackground:draw_fore() end

function ImasSidemBackground:destroy()
    self.donbg:destroy()
    self.bg_normal:destroy()
    self.bg_fever:destroy()
    self.fever:destroy()
    self.dancer:destroy()
    self.footer:destroy()
    self.renda:destroy()
    self.chibi:destroy()
end

return ImasSidemBackground