-- Shared Gen 2 menu chrome: boxes, tile-grid text, and the scrolling cursor
-- list that nearly every Gold screen is built out of.
--
-- Gold draws its menus through one routine (engine/menus/menu.asm SetUpMenu +
-- GetScrollingMenuJoypad), so the behaviour every screen inherits -- wrap at
-- the ends, a ▶ cursor in a one-tile gutter, B to back out, START as an
-- accept on some menus -- lives here once instead of in each screen.
--
-- Everything is in 8px tile coordinates on the 20x18 GB grid, because that is
-- how the ASM addresses the screen (hlcoord x, y) and it makes a layout
-- transcribed from pokegold land on the same pixels.

local Font = require("src.render.Font")
local GbcPalette = require("src.render.GbcPalette")

local Chrome = {}

-- charmap.asm: ▶ is the menu cursor, ▷ its hollow "held" form, ▼ the
-- text-advance arrow.
Chrome.CURSOR = 0xED
Chrome.CURSOR_HOLLOW = 0xEC
Chrome.DOWN_ARROW = 0xEE

Chrome.SCREEN_W = 20
Chrome.SCREEN_H = 18

-- charmap.asm "¥", the money field's own prefix tile.
local YEN = "\xc2\xa5"

function Chrome.clear()
  local G = love.graphics
  G.setColor(1, 1, 1, 1)
  G.rectangle("fill", 0, 0, Chrome.SCREEN_W * 8, Chrome.SCREEN_H * 8)
  G.setColor(0, 0, 0, 1)
end

-- The blit scale every `drawWidescreen` paints its 160x144 panel at.
--
-- One GB pixel has to cover a WHOLE number of window pixels or the 8x8 grid
-- everything here is laid out on stops landing on tile boundaries: at a
-- fractional scale some rows of a tile get one device pixel and their
-- neighbours get two, which is what breaks a box border into steps and eats
-- pixel rows out of glyphs.  This is the same rule src/render/Renderer.lua
-- fitScale applies to the Gen 1 UI canvas; the surround a widescreen screen
-- paints still fills the window, the PANEL is what stays on the grid.
function Chrome.fitScale(winW, winH)
  return math.max(1, math.floor(math.min((winW or 0) / (Chrome.SCREEN_W * 8),
    (winH or 0) / (Chrome.SCREEN_H * 8))))
end

-- The centred origin that goes with it, so a caller does not re-derive it.
function Chrome.fitOrigin(winW, winH, scale)
  scale = scale or Chrome.fitScale(winW, winH)
  return math.floor((winW - Chrome.SCREEN_W * 8 * scale) / 2),
    math.floor((winH - Chrome.SCREEN_H * 8 * scale) / 2)
end

-- A bordered box, tile coords.  Leaves the draw color black for text.
function Chrome.box(tx, ty, tw, th)
  Font.drawBox(tx, ty, tw, th)
  love.graphics.setColor(0, 0, 0, 1)
end

-- Gold's Textbox helper takes an interior width/height and draws the border
-- around it; b/c in the ASM are interior rows/columns, so a `lb bc, 4, 13`
-- box is 6 rows by 15 columns on screen.
function Chrome.textbox(tx, ty, interiorW, interiorH)
  Chrome.box(tx, ty, interiorW + 2, interiorH + 2)
end

function Chrome.print(text, tx, ty)
  love.graphics.setColor(0, 0, 0, 1)
  return Font.draw(text, tx * 8, ty * 8)
end

-- Prints a string the way a tilemap screen does: the glyph tiles replace the
-- cells they land on, and both their ink and their blank pixels go through
-- that screen's own BG palette.
--
-- The font sheets here are black ink (shade 3) on transparent, and setColor
-- multiplies -- black times anything is still black -- so the ink colour
-- cannot come from a tint.  Drawing through GbcPalette maps shade 3 to the
-- palette's colour 3, and painting colour 0 behind the string first supplies
-- the cell background the sheet does not carry.  Without a shader this
-- degrades to the ordinary black print rather than drawing nothing.
--
-- The palette printThrough actually draws with: COLOR mode resolved,
-- inverted if asked, and the active rBGP byte folded in last -- the same
-- order GbcPalette.use follows.  Split out so the fold can be checked
-- without a real shader (GbcPalette.available() is false in a driverless
-- test harness, which used to hide this from every suite).
--
-- The substitution has to happen before the reversal or an inverted string
-- would come back through an un-reversed grey ramp and print black on white,
-- and the rBGP fold has to come after both: it REORDERS the four entries
-- this palette already settled on (colour 0 in the low bits, so
-- `dc 3,2,1,0` packs to $e4), it does not tint them, so folding it before
-- the invert reversal would permute the wrong four colours.
function Chrome.throughPalette(palette, invert)
  local pal = GbcPalette.resolve(palette)
  if invert then pal = { pal[4], pal[3], pal[2], pal[1] } end
  return GbcPalette.remap(pal, GbcPalette.bgp)
end

-- `palette` is a 4-colour table of 0-255 triples.  `invert` is what
-- Chrome.printInverted passes; see there.
function Chrome.printThrough(text, tx, ty, palette, invert)
  if not (palette and GbcPalette.available()) then
    return Chrome.print(text, tx, ty)
  end
  -- `pal` is used below and never touches the caller's palette again --
  -- including useRaw for the draw, since useRaw skips the fold GbcPalette.use
  -- would otherwise apply and folding it a second time would undo this.
  local pal = Chrome.throughPalette(palette, invert)
  local width = Font.width(text)
  local paper = pal[1] or { 255, 255, 255 }
  love.graphics.setColor(paper[1] / 255, paper[2] / 255, paper[3] / 255, 1)
  love.graphics.rectangle("fill", tx * 8, ty * 8, width, 8)
  love.graphics.setColor(1, 1, 1, 1)
  local previous = love.graphics.getShader()
  GbcPalette.useRaw(pal)
  Font.draw(text, tx * 8, ty * 8)
  love.graphics.setShader(previous)
  love.graphics.setColor(0, 0, 0, 1)
  return width
end

-- The same, through an *inverted* font page.  Pokedex_LoadInvertedFont xors
-- both bitplanes of the standard font, so a glyph pixel of shade s becomes
-- shade 3 - s before the palette sees it -- which is exactly the palette read
-- backwards, and is what makes the dex white on black.
function Chrome.printInverted(text, tx, ty, palette)
  if not palette then return Chrome.print(text, tx, ty) end
  return Chrome.printThrough(text, tx, ty, palette, true)
end

-- Right-aligned within a field that ends at tile `txEnd` (exclusive), which is
-- how Gold prints numbers (PrintNum fills from the right).
function Chrome.printRight(text, txEnd, ty)
  local width = Font.width(text)
  love.graphics.setColor(0, 0, 0, 1)
  return Font.draw(text, txEnd * 8 - width, ty * 8)
end

-- Wrap text to `width` tiles, measuring with the real font so a proportional
-- page wraps where it actually overflows.  Nothing on a 160px screen may print
-- past tile 20: text that does is drawn outside the GB frame entirely.
-- A "\n" in the text is the cart's OWN line break (data/text's `line` / `next`
-- control byte, e.g. "<USER>\nused <MOVE>!"), so it is a HARD break: each
-- segment wraps on its own and the break survives, rather than being eaten by
-- the %S+ tokenizer and re-wrapped by width.
function Chrome.wrap(text, width)
  local budget = (width or Chrome.SCREEN_W) * 8
  local lines = {}
  for segment in (tostring(text or "") .. "\n"):gmatch("(.-)\n") do
    local line = nil
    for word in segment:gmatch("%S+") do
      local candidate = line and (line .. " " .. word) or word
      if line and Font.width(candidate) > budget then
        lines[#lines + 1] = line
        line = word
      else
        line = candidate
      end
    end
    if line then lines[#lines + 1] = line end
  end
  return lines
end

-- Print wrapped text from (tx, ty) downward, at most `rows` lines.
function Chrome.printWrapped(text, tx, ty, width, rows)
  local lines = Chrome.wrap(text, width)
  for i = 1, math.min(#lines, rows or #lines) do
    Chrome.print(lines[i], tx, ty + i - 1)
  end
  return #lines
end

function Chrome.cursor(tx, ty, hollow)
  love.graphics.setColor(0, 0, 0, 1)
  Font.drawCode(hollow and Chrome.CURSOR_HOLLOW or Chrome.CURSOR, tx * 8, ty * 8)
end

-- The cursor glyph through a palette, the way Chrome.printThrough draws text.
-- A screen whose font page is inverted (the #DEX: Pokedex_LoadInvertedFont
-- xors both bitplanes, so it runs white on black) needs its cursor inverted
-- with everything else -- Chrome.cursor's flat black is invisible against that
-- ground, which is what made the dex's action arrow look absent.
function Chrome.cursorThrough(tx, ty, palette, invert, hollow)
  if not (palette and GbcPalette.available()) then
    return Chrome.cursor(tx, ty, hollow)
  end
  local pal = Chrome.throughPalette(palette, invert)
  local paper = pal[1] or { 255, 255, 255 }
  love.graphics.setColor(paper[1] / 255, paper[2] / 255, paper[3] / 255, 1)
  love.graphics.rectangle("fill", tx * 8, ty * 8, 8, 8)
  love.graphics.setColor(1, 1, 1, 1)
  local previous = love.graphics.getShader()
  GbcPalette.useRaw(pal)
  Font.drawCode(hollow and Chrome.CURSOR_HOLLOW or Chrome.CURSOR, tx * 8, ty * 8)
  love.graphics.setShader(previous)
  love.graphics.setColor(0, 0, 0, 1)
end

-- Gold pads a numeric field with spaces, not zeroes, unless
-- PRINTNUM_LEADINGZEROS is set.
function Chrome.number(value, width, leadingZeros)
  local text = tostring(math.floor(value or 0))
  local pad = math.max(0, (width or 0) - #text)
  return (leadingZeros and ("0"):rep(pad) or (" "):rep(pad)) .. text
end

-- PrintNum with PRINTNUM_MONEY and without PRINTNUM_LEADINGZEROS
-- (home/print_num.asm .PrintYen): the ¥ is emitted just before the FIRST
-- significant digit rather than at a fixed column, and the field is six digits
-- wide, so the string is always seven tiles and the yen sign floats.
function Chrome.money(amount)
  local digits = ("%06d"):format(math.max(0, math.floor(amount or 0)))
  local first = digits:find("[1-9]") or #digits
  return (" "):rep(first - 1) .. YEN .. digits:sub(first)
end

-- ------------------------------------------------------- balance boxes
--
-- engine/menus/menu_2.asm.  These three are the boxes a SCRIPT puts up with a
-- `special` and then leaves standing: every one of them is immediately
-- followed by `loadmenu`, so the box is on screen for the whole of the static
-- menu that answers.  They live here rather than in one menu module because
-- three different screens print them (the Game Corner prize counters and the
-- coin vendor through src/ui/gen2/ScriptMenu.lua, the prize counter screen
-- itself) and all three are laid out by the same two routines.
--
-- DisplayCoinCaseBalance: Textbox at (11,0) with a 7x1 interior, "COIN" at
-- (12,0) -- yes, in the border row -- and the four-digit count at (13,1) with
-- PRINTNUM_LEADINGZEROS.
function Chrome.coinBalanceBox(coins)
  Chrome.textbox(11, 0, 7, 1)
  Chrome.print("COIN", 12, 0)
  Chrome.print(Chrome.number(coins, 4, true), 13, 1)
end

-- DisplayMoneyAndCoinBalance: one Textbox at (5,0) with a 13x3 interior
-- holding both fields, "MONEY" at (6,1) with the yen field at (12,1) and
-- "COIN" at (6,3) with the four-digit count at (15,3).
function Chrome.moneyAndCoinBalanceBox(money, coins)
  Chrome.textbox(5, 0, 13, 3)
  Chrome.print("MONEY", 6, 1)
  Chrome.print(Chrome.money(money), 12, 1)
  Chrome.print("COIN", 6, 3)
  Chrome.print(Chrome.number(coins, 4, true), 15, 3)
end

-- PlaceMoneyTopRight: MoneyTopRightMenuHeader is `menu_coords 11, 0,
-- SCREEN_WIDTH - 1, 2`, a MenuBox rather than a Textbox, and PlaceMoneyTextbox
-- prints the number at MenuBoxCoord2Tile + SCREEN_WIDTH + 1, i.e. (12,1).
function Chrome.moneyBalanceBox(money)
  Chrome.box(11, 0, 9, 3)
  Chrome.print(Chrome.money(money), 12, 1)
end

-- A vertical cursor list.
--
-- opts:
--   items      array of strings, or of { label = , value = , disabled = }
--   x, y       tile coords of the first row's *label* (cursor sits at x - 1)
--   spacing    tile rows between entries (Gold uses 2 for most menus)
--   rows       visible rows; a longer list scrolls (default: all)
--   wrap       wrap past the ends (STATICMENU_WRAP)
--   startAccepts  treat START like A (STATICMENU_ENABLE_START)
--   onChoose(value, index)
--   onCancel()
--   onMove(value, index)  -- for the start menu's description box
local List = {}
List.__index = List
Chrome.List = List

function List.new(opts)
  local self = setmetatable({}, List)
  self.items = {}
  for i, entry in ipairs(opts.items or {}) do
    if type(entry) == "table" then
      self.items[i] = entry
    else
      self.items[i] = { label = tostring(entry), value = entry }
    end
  end
  self.x = opts.x or 1
  self.y = opts.y or 1
  self.spacing = opts.spacing or 2
  self.rows = math.min(opts.rows or #self.items, #self.items)
  self.wrap = opts.wrap ~= false
  self.startAccepts = opts.startAccepts or false
  self.onChoose = opts.onChoose
  self.onCancel = opts.onCancel
  self.onMove = opts.onMove
  self.index = math.max(1, math.min(opts.index or 1, math.max(1, #self.items)))
  self.scroll = 0
  self:ensureVisible()
  return self
end

function List:current()
  return self.items[self.index]
end

function List:ensureVisible()
  if self.rows <= 0 then return end
  if self.index <= self.scroll then
    self.scroll = self.index - 1
  elseif self.index > self.scroll + self.rows then
    self.scroll = self.index - self.rows
  end
  self.scroll = math.max(0, math.min(self.scroll, #self.items - self.rows))
end

function List:move(delta)
  if #self.items == 0 then return end
  local next_ = self.index + delta
  if next_ < 1 then
    if not self.wrap then return end
    next_ = #self.items
  elseif next_ > #self.items then
    if not self.wrap then return end
    next_ = 1
  end
  self.index = next_
  self:ensureVisible()
  if self.onMove then self.onMove(self:current() and self:current().value, self.index) end
end

-- Returns true when the press was consumed, so a screen can layer its own
-- handling (left/right on the options rows) behind this.
function List:update(input)
  if not input then return false end
  if input:wasPressed("up") then
    self:move(-1)
    return true
  elseif input:wasPressed("down") then
    self:move(1)
    return true
  elseif input:wasPressed("a")
      or (self.startAccepts and input:wasPressed("start")) then
    local item = self:current()
    if item and not item.disabled and self.onChoose then
      self.onChoose(item.value, self.index)
    end
    return true
  elseif input:wasPressed("b") then
    if self.onCancel then self.onCancel() end
    return true
  end
  return false
end

function List:draw()
  for row = 1, self.rows do
    local i = row + self.scroll
    local item = self.items[i]
    if item then
      local ty = self.y + (row - 1) * self.spacing
      if i == self.index then Chrome.cursor(self.x - 1, ty) end
      Chrome.print(item.label, self.x, ty)
    end
  end
  -- Scrolling lists get the ▼ hint Gold shows when there is more below.
  if self.rows < #self.items and self.scroll + self.rows < #self.items then
    love.graphics.setColor(0, 0, 0, 1)
    Font.drawCode(Chrome.DOWN_ARROW, (self.x - 1) * 8,
      (self.y + self.rows * self.spacing - 1) * 8)
  end
end

return Chrome