-- STADIUM battles: the one-time build, on screen.
--
-- A pushed game state, so it draws in the Game Boy's own 160x144 and stops
-- everything under it -- which is what it should do, because it is doing real
-- work and the player should not be walking around while it happens.
--
-- ------- why a species a frame
--
-- A species takes roughly fifty milliseconds to extract, and there are 151 of
-- them. That is ten seconds, which has to go somewhere. Doing them one per
-- frame puts the whole cost on this screen where it is explained, keeps the
-- bar moving at a visible rate, and leaves the frame free to draw between
-- them. Batching more per frame would finish no sooner -- the work is the
-- same -- and would only make the bar jump.
--
-- ------- what it says
--
-- Three things, and each of them is answering a question the player would
-- otherwise have to guess at while the game sits there:
--
--   WHAT is happening -- "ONE-TIME EXTRACTION OF STADIUM ASSETS", in those
--   words, because the two facts that matter to somebody who has just
--   installed a mod and been handed a loading screen are that this is the
--   mod's own asset build and that it is not going to happen again.
--
--   HOW FAR through it is -- a bar, filled by species written rather than by
--   elapsed time, so it cannot lie about the remaining work.
--
--   THAT IT IS ALIVE -- which Pokemon it is on, by name. Not decoration: it
--   is the difference between a progress bar the player trusts and one they
--   suspect has hung, and it costs one lookup a frame.

-- the mod namespace (see main.lua): V.require loads a sibling module
local V = ...

local StadiumInstall = V.require("StadiumInstall")

local StadiumScreen = {}
StadiumScreen.__index = StadiumScreen

-- The Game Boy frame this draws in.
local W, H = 160, 144

-- How long the finished message stays up before the screen retires itself.
StadiumScreen.HOLD = 1.1

local Font = nil
local function font()
  if Font then return Font end
  local ok, F = pcall(require, "src.render.Font")
  if ok then Font = F end
  return Font
end

-- Black glyphs, because that is the only colour the Game Boy font sheets
-- have -- they are black on transparent, so setColor cannot lighten one.
-- Everything here is therefore laid out dark-on-light.
local function text(str, x, y)
  local F = font()
  if not F then return end
  love.graphics.setColor(0, 0, 0, 1)
  F.draw(str, math.floor(x), math.floor(y))
end

local function centred(str, y)
  local F = font()
  if not F then return end
  text(str, (W - F.width(str)) / 2, y)
end

-- ------- dex number -> the engine's own species key
--
-- Built once, from the loaded data rather than from a list of names carried
-- here: a list would be a second place for the same 151 facts to live, and
-- would go stale against a mod that renames one.
local dexNames = nil

local function speciesName(dex)
  if not dex then return nil end
  if not dexNames then
    dexNames = {}
    local ok, data = pcall(function()
      return require("src.core.Game").data
    end)
    if ok and data and data.pokemon then
      for key, def in pairs(data.pokemon) do
        if type(def) == "table" and def.dex then dexNames[def.dex] = key end
      end
    end
  end
  return dexNames[dex]
end

function StadiumScreen.new(game)
  return setmetatable({ game = game, hold = 0, started = false }, StadiumScreen)
end

-- Opaque: the loading screen owns the frame, so the map underneath is not
-- drawn and not paying for a render it cannot be seen through.
StadiumScreen.isOpaque = true

function StadiumScreen:enter()
  local ok, err = StadiumInstall.begin()
  self.started = ok and true or false
  if not ok then
    StadiumInstall.status.state = "failed"
    StadiumInstall.status.error = err
  end
end

function StadiumScreen:update()
  local status = StadiumInstall.status
  if status.state == "building" then
    if not StadiumInstall.step() then
      -- fell out of building: either finished or failed, both of which hold
      -- for a moment so the player sees which
      self.hold = 0
    end
    return
  end
  self.hold = self.hold + 1 / 60
  -- a failure stays up longer, because it is the one the player has to read
  local wait = (status.state == "failed") and StadiumScreen.HOLD * 4
               or StadiumScreen.HOLD
  if self.hold >= wait then
    if self.game and self.game.stack and self.game.stack:top() == self then
      self.game.stack:pop()
    end
  end
end

-- Let the player out of a build that has gone wrong, or that they would
-- rather not wait for. Cancelling leaves the packs unbuilt, so the STADIUM
-- rungs stay off the row until the next boot offers again -- which is
-- honest, and better than a half-built set.
function StadiumScreen:onKeyPressed(key)
  if key == "escape" or key == "x" or key == "backspace" then
    StadiumInstall.cancel()
    if self.game and self.game.stack and self.game.stack:top() == self then
      self.game.stack:pop()
    end
    return true
  end
  return false
end

function StadiumScreen:draw()
  local status = StadiumInstall.status
  love.graphics.setColor(0.93, 0.94, 0.90, 1)
  love.graphics.rectangle("fill", 0, 0, W, H)

  centred("POKEMON STADIUM", 16)
  -- the headline, in two lines because the frame is 160 pixels wide and the
  -- font is a fixed eight: the longer of these is nineteen glyphs
  centred("ONE-TIME EXTRACTION", 36)
  centred("OF STADIUM ASSETS", 46)

  if status.state == "failed" then
    centred("COULD NOT BUILD", 70)
    local why = tostring(status.error or "unknown"):sub(1, 24)
    centred(why, 84)
    centred("STADIUM IS OFF", 104)
    love.graphics.setColor(1, 1, 1, 1)
    return
  end

  local done = status.done or 0
  local total = status.total or StadiumInstall.COUNT
  local frac = (total > 0) and (done / total) or 1
  if status.state == "done" then frac = 1 end
  if frac < 0 then frac = 0 elseif frac > 1 then frac = 1 end

  -- The bar: a dark frame, an EMPTY interior the same colour as the plate,
  -- and a dark fill growing left to right.
  --
  -- The track has to be the plate's own white rather than a light grey. This
  -- draws inside the Game Boy frame, so the colorization pass quantises
  -- everything here into the four GB shades and paints them -- and a grey
  -- track lands one shade down, which comes out as a bar that is GREEN where
  -- the work is still to do and dark where it is done. The eye reads colour
  -- as the filled part and gets the progress exactly backwards.
  local bx, by, bw, bh = 24, 68, W - 48, 9
  love.graphics.setColor(0.06, 0.05, 0.09, 1)
  love.graphics.rectangle("fill", bx - 1, by - 1, bw + 2, bh + 2)
  love.graphics.setColor(0.93, 0.94, 0.90, 1)
  love.graphics.rectangle("fill", bx, by, bw, bh)
  love.graphics.setColor(0.06, 0.05, 0.09, 1)
  love.graphics.rectangle("fill", bx, by, math.floor(bw * frac + 0.5), bh)

  if status.state == "done" then
    centred("READY", 86)
  else
    local name = speciesName(status.species)
    centred(("%d/%d"):format(done, total), 86)
    if name then centred(name, 98) end
    -- last, and lowest: the reassurance is worth saying and is the least
    -- urgent thing on the plate
    centred("THIS RUNS ONCE", 122)
  end
  love.graphics.setColor(1, 1, 1, 1)
end

-- ------- when this comes up
--
-- The first frame the player is actually IN the world, rather than at boot.
-- Two reasons. The engine has its own launcher and ROM importer before the
-- game starts, and pushing over those would be fighting them for the screen.
-- And `Game.data` has to be loaded for the species names above to resolve.
--
-- Asked once. If the player cancels, or there is no ROM, this does not come
-- back until the next run -- a loading screen that reappears every time you
-- step outside would be worse than no stadium models.
local asked = false

function StadiumScreen.maybePush()
  if asked then return false end
  local ok, Game = pcall(require, "src.core.Game")
  if not (ok and Game and Game.stack and Game.overworld) then return false end
  if Game.stack:top() ~= Game.overworld then return false end
  asked = true
  if not StadiumInstall.pending() then
    -- Say where to put a cartridge, ONCE, and only when there is nothing to
    -- build from and nothing already built. The two STADIUM rungs are simply
    -- absent in that case (ModSetting.setGate), which is the right thing for
    -- a row to do and tells the player nothing about why -- and the answer
    -- they need is an absolute path that depends on how the game was
    -- installed, so it cannot be written into the options help text.
    if not StadiumInstall.available() then
      V.mod.log:info("stadium: no Pokemon Stadium ROM found, so the STADIUM "
                     .. "battle rungs are off. Put one (.z64/.n64/.v64) in "
                     .. "%s and restart.", StadiumInstall.romHint())
    end
    return false
  end
  Game.stack:push(StadiumScreen.new(Game))
  return true
end

-- named for the suite, which drives the screen without a boot
function StadiumScreen._reset()
  asked = false
end

return StadiumScreen