-- details.lua — "tell me more about what is focused".
--
-- Focus announcements are deliberately terse: "a torch, slot 1". Everything that
-- says what an item actually IS -- description, condition, what it refines into,
-- what a recipe costs, what it sells for -- is on screen but was never spoken.
--
--------------------------------------------------------------------------------
-- Why details settle rather than always speaking
--------------------------------------------------------------------------------
--
-- The game itself gates this text behind a dwell: the cursor popup only fades in
-- after config.get("examinationPopupFadeInDuration") (default 0.4s). Arrow past a
-- slot quickly and a SIGHTED player never sees the details either -- they see them
-- by stopping. So we mirror that rather than inventing a modality: stop on a slot
-- and the details speak themselves; keep moving and they don't.
--
-- `=` reads them on demand and re-reads them, for when you don't want to wait or
-- the utterance went by. Shift+= is verbose (keeps the name line too).
--
--------------------------------------------------------------------------------
-- The descriptor hook
--------------------------------------------------------------------------------
--
--   descriptor.details(stateTable, menus, verbose) -> { "block", "block", ... }
--
-- Optional, alongside read/reset. Returning a LIST rather than one string is what
-- lets each block be pushed into the console history separately, so [ and ] walk
-- the detail text back afterwards -- the same trick states/journal.lua uses for
-- journal pages. A long description therefore never has to be caught first time.
--
-- Implemented so far by the four item-grid screens (_itemgrid.lua). Any other
-- descriptor can gain it for free: research nodes and examine-mode tiles are the
-- obvious next ones.

local speech = require("accessibility.speech")
local history = require("accessibility.history")
local menus = require("accessibility.menus")

local details = {}

details.config = {
	-- How long focus must stay still before details speak, in seconds. Longer
	-- than the game's 0.4s popup delay because speech takes longer than a glance,
	-- and arrowing through a full tab shouldn't leave a backlog behind you.
	settleDelay = 0.6,

	-- Set false to make details key-only.
	autoSpeak = true,
}

--------------------------------------------------------------------------------
-- Fetching
--------------------------------------------------------------------------------

-- Returns the detail blocks for a state, or nil if it has no details to give.
function details.get(stateName, verbose)
	local descriptor = menus.loadDescriptor(stateName)
	if not descriptor or not descriptor.details then
		return nil
	end

	local stateTable = menus.getStateTable(stateName)
	if not stateTable then
		return nil
	end

	local ok, blocks = pcall(descriptor.details, stateTable, menus, verbose)
	if not ok or type(blocks) ~= "table" or #blocks == 0 then
		return nil
	end

	return blocks
end

--------------------------------------------------------------------------------
-- Speaking
--------------------------------------------------------------------------------

local function currentState()
	local ok, states = pcall(require, "states")
	if not ok then
		return nil
	end
	return states.getCurrent()
end

-- Mirror into the review buffer so [ and ] can walk the blocks after the
-- utterance has gone by.
local function pushToHistory(blocks)
	for _, block in ipairs(blocks) do
		pcall(history.append, block, "details")
	end
end

local function speakBlocks(blocks, interrupt)
	pushToHistory(blocks)
	speech.say(table.concat(blocks, ". "), interrupt)
end

-- The `=` key. Interrupting, because the player explicitly asked.
function details.speak(verbose)
	local stateName = currentState()
	local blocks = stateName and details.get(stateName, verbose)

	if not blocks then
		-- Never a silent no-op: silence is indistinguishable from a dropped key.
		speech.say("No details", true)
		return
	end

	speakBlocks(blocks, true)
end

--------------------------------------------------------------------------------
-- The settle timer
--------------------------------------------------------------------------------

local settledKey  -- focus key currently being timed
local settledTime -- how long it has been unchanged
local spokenKey   -- focus key we have already spoken details for
local lastState   -- so leaving a screen and coming back speaks again

-- Pure, and exposed for the testbed: advance the timer for `key` by `dt` and say
-- whether details are due now. Due exactly once per focus key -- without that,
-- a stationary cursor would re-speak every frame.
function details.settleStep(key, dt)
	if key ~= settledKey then
		settledKey = key
		settledTime = 0
		return false
	end

	if key == nil or key == spokenKey then
		return false
	end

	settledTime = (settledTime or 0) + (dt or 0)

	if settledTime < details.config.settleDelay then
		return false
	end

	spokenKey = key
	return true
end

function details.reset()
	settledKey = nil
	settledTime = nil
	spokenKey = nil
end

-- Called once per frame from init.lua's update hook.
function details.update(dt)
	if not details.config.autoSpeak then
		return
	end

	local stateName = currentState()
	if not stateName then
		return
	end

	-- The focus key is state-qualified, so without this, leaving a screen and
	-- returning to the same slot would be "already spoken" and stay silent.
	if stateName ~= lastState then
		lastState = stateName
		details.reset()
	end

	local descriptor = menus.loadDescriptor(stateName)
	if not descriptor or not descriptor.details then
		details.reset()
		return
	end

	-- Only the focus KEY is wanted here; readFocus's text is what read() already
	-- announced and must not be repeated.
	local _, key = menus.readFocus(stateName)

	-- No focus key means the descriptor could not read the screen this frame
	-- (mid-transition, window not built yet). Don't time an unknown.
	if key == nil then
		details.reset()
		return
	end

	if not details.settleStep(stateName .. "|" .. key, dt) then
		return
	end

	local blocks = details.get(stateName, false)
	if not blocks then
		return
	end

	-- Queued, not interrupting: this is background awareness the player did not
	-- ask for, so anything they DID ask for outranks it.
	speakBlocks(blocks, false)
end

function details.registerKeys(hotkeys)
	hotkeys.bind("=", nil, function() details.speak(false) end)
	hotkeys.bind("=", "shift", function() details.speak(true) end)
end

return details