-- Dramatic Shape Voxel Mod: a full 3D diorama overworld, shipped as a
-- rendering pipeline mod.
--
-- The engine's render_pipelines registry (src/mods/Schemas.lua) lets a mod
-- own part of the frame.  This mod registers two:
--
--   voxel      a drawWorld pipeline.  Instead of the flat tile blit, the
--              overworld's terrain is extruded into real geometry, walked
--              by a depth-buffered 3D camera, with characters as leaning
--              sprite slabs and a shadow map throwing real cast shadows
--              across whatever they land on.  Occlusion is the depth
--              buffer, not a y-sort: walk behind a building and the
--              building is simply in front.
--
--   tiltshift  a worldPresent pipeline -- the stage that post-processes
--              the finished world BEFORE the UI composites over it.  A
--              tilt-shift blur that sells the miniature-model look, on the
--              diorama only, leaving text boxes and menus crisp.
--
-- Everything a display mode needs beyond the two draw functions -- the
-- OFF/15/35/50 ladder, the options rows, the hotkeys, persistence in
-- save.options.pipelines, the free-roam gate, the mutual exclusion with
-- the engine's TILT mode -- is engine plumbing driven by the records
-- below.  This file declares; lib/ draws.
--
-- Nothing here reaches collision, movement, triggers or scripts.  Voxel
-- mode is purely presentational: it changes what the world LOOKS like and
-- nothing about what it IS.

local mod = ...

-- ------- the mod namespace
--
-- lib/ modules require each other through V rather than package.path: a
-- mod directory is not on it, and may live inside a mounted .love archive
-- that plain require cannot reach.  Each module is loaded once, with V
-- passed in as its vararg (`local V = ...`).

local V = { mod = mod, path = mod.path }

local function chunkFor(rel)
  local source = mod:read(rel)
  if not source then
    error(("DRAMATIC_SHAPE: %s is missing -- reinstall the mod"):format(rel), 0)
  end
  local chunk, err = load(source, "@" .. mod.path .. "/" .. rel)
  if not chunk then
    error(("DRAMATIC_SHAPE: %s did not compile: %s"):format(rel, tostring(err)), 0)
  end
  return chunk
end

local modules = {}
function V.require(name)
  local hit = modules[name]
  if hit ~= nil then return hit end
  local value = chunkFor("lib/" .. name .. ".lua")(V)
  modules[name] = value
  return value
end

local dataFiles = {}
function V.data(name)
  local hit = dataFiles[name]
  if hit ~= nil then return hit end
  local value = chunkFor("data/" .. name .. ".lua")(V)
  dataFiles[name] = value
  return value
end

-- ------- pipelines

local Voxel = V.require("VoxelState")
local Voxel3D = V.require("Voxel3D")
local VoxelScene = V.require("VoxelScene")
local TiltShift = V.require("TiltShift")
local ChunkMesher = V.require("ChunkMesher")
local VoxelGrid = V.require("VoxelGrid")
local WorldCurve = V.require("WorldCurve")

-- The last VOID FILL the terrain was meshed under; see the update hook.
local voidFill = { last = nil }
function voidFill.check()
  local TileRenderer = require("src.render.TileRenderer")
  local now = TileRenderer.voidFill
  if voidFill.last ~= nil and now ~= voidFill.last then
    ChunkMesher.invalidate()   -- no map id: every ring on every map is stale
  end
  voidFill.last = now
end

mod.content.render_pipelines:register("voxel", {
  label = "VOXEL",
  levels = Voxel.ANGLE_LABELS,
  -- 2/3/4/5 are the engine's own display hotkeys
  hotkey = "6",
  -- above tiltshift, so the two sort together in the options list with the
  -- mode first and its post-process under it
  priority = 20,

  -- Headless runs and drivers without a depth canvas or shader support
  -- answer false here, and the engine keeps the vanilla 2D path -- which
  -- is why no caller ever has to guard for a missing 3D pass.
  available = function()
    return Voxel3D.available()
  end,

  -- the engine hands over the live level; we ease the camera toward it.
  -- pump() advances queued mesh builds inside a few-millisecond budget,
  -- so entering voxel mode (and streaming neighbours while walking)
  -- costs frames nothing visible -- the old synchronous build froze the
  -- first frame for seconds. prefetch() runs here as well as in the
  -- draw, because update ticks even while a warp's Transition covers
  -- the screen: the destination's meshes start building the moment the
  -- map swaps behind the fade, and the fade-covered frames get a wider
  -- pump slice -- so stepping out of a door lands on terrain that is
  -- already there instead of a flat flash.
  update = function(dt, level)
    Voxel.update(dt, level)
    -- VOID FILL picks the block the border ring is made of, and in this
    -- mode that ring is BAKED INTO THE MESH rather than drawn each frame.
    -- So the option has to reach the cache or nothing happens on screen
    -- until the meshes are dropped for some other reason -- which reads
    -- exactly like the option doing nothing at all. Polled rather than
    -- hooked because the engine changes it from three places (the options
    -- row, applyOptions on load, TileRenderer.setVoidFill) and none of
    -- them announces it. Ahead of the active() gate, so switching it
    -- while voxel mode is OFF still invalidates what is cached.
    voidFill.check()
    if not Voxel.active() then return end
    local Game = require("src.core.Game")
    local ow = Game and Game.overworld
    if ow and ow.map and ow.camera then
      pcall(VoxelScene.prefetch, ow)
    end
    ChunkMesher.pump(Game and Game.stack
                     and Game.stack:top() ~= ow)
  end,

  drawWorld = function(ctx)
    -- Terrain and characters are geometry; the field FX stay ordinary 2D
    -- draws composited on top, anchored through the same camera the 3D
    -- pass used (ctx.drawFx below).  The scene renders at window
    -- resolution so the 3D pass is crisp rather than a magnified low-res
    -- image, while the FX closures keep drawing in world-pixel units.
    local canvas = VoxelScene.render(ctx.state, ctx.width, ctx.height,
                                     ctx.vw, ctx.vh, ctx.paletteFor)
    if not canvas then return nil end   -- fall back to the 2D path
    if Voxel3D.beginOverlay() then
      ctx.drawFx(function(wx, wy) return Voxel3D.project(wx, 0, wy) end,
                 ctx.scale)
      Voxel3D.endOverlay()
    end
    return canvas
  end,

  invalidate = function()
    Voxel3D.invalidate()
    ChunkMesher.invalidate()   -- no map id = every cached mesh
  end,
})

mod.content.render_pipelines:register("tiltshift", {
  label = "T-SHIFT",
  levels = TiltShift.LABELS,
  hotkey = "9",
  priority = 10,

  update = function(dt, level)
    TiltShift.update(dt, level)
  end,

  -- worldPresent, not present: the blur belongs on the diorama, not on the
  -- dialog box in front of it.  A pass-through when the level is 0 or the
  -- shader is unavailable, so the frame is untouched in every other case.
  worldPresent = function(canvas)
    return TiltShift.apply(canvas)
  end,

  invalidate = function()
    TiltShift.invalidate()
  end,
})

-- ------- this mod's own settings
--
-- Neither of these is a pipeline: they own no pass of the frame, they
-- PARAMETERISE the voxel one, so they have nothing to put in drawWorld or
-- present and the registry would rightly reject them.  Plain mod settings
-- instead -- see ModSetting for where they persist and how the two rows
-- each ends up on stay in step.

local SETTINGS = {
  { VoxelGrid.setting, "One-pixel wireframe along every voxel edge." },
  { WorldCurve.setting,
    "Bend the world down over the horizon, Animal Crossing style." },
}

local schema = {}
for i, entry in ipairs(SETTINGS) do
  schema[i] = entry[1]:schema(entry[2])
end
mod.options:define(schema)

-- call next() first and decorate what comes back, so every other mod's
-- rows survive this one
mod.hooks:wrap("ui.options.rows", function(next, game, rows)
  local out = next(game, rows)
  if type(out) ~= "table" then return out end
  for _, entry in ipairs(SETTINGS) do
    out[#out + 1] = entry[1]:row()
  end
  return out
end)

-- The mod manager writes and persists on its own, so the only thing left
-- to do is move our cached index and pick the new value up.
mod.events:on("mod.options_changed", function(payload)
  if not (payload and payload.mod == mod.id) then return end
  for _, entry in ipairs(SETTINGS) do
    if payload.key == entry[1].key then entry[1]:sync(payload.value) end
  end
end)

-- ------- keeping the geometry in step with the world
--
-- Terrain meshes are derived from a map's block layer, so anything that
-- rewrites a block (a cut tree, a smashed rock, a script's replaceBlock)
-- has to drop that map's cached mesh or the 3D world keeps showing the
-- tree that is no longer there.  The 2D tile renderer invalidates its own
-- caches off the same edit.

mod.events:on("world.block_replaced", function(payload)
  local mapId = payload and (payload.mapId or (payload.map and payload.map.id))
  if mapId then ChunkMesher.invalidate(mapId) end
end)

-- A reloaded map is rebuilt from scratch (palette pack switches, warps
-- that re-enter the same map), so its mesh is stale for the same reason.
mod.events:on("map.reloaded", function(payload)
  local mapId = payload and (payload.mapId or (payload.map and payload.map.id))
  if mapId then ChunkMesher.invalidate(mapId) end
end)

mod.exports.version = "1.0.0"
-- exposed so a companion mod can pin its own tiles' shapes or read the
-- camera without reaching into this mod's file layout
mod.exports.lib = V