-- states/research.lua — the research tree.
--
-- Not a list: a 2D graph of nodes navigated with the arrow keys, where up/down
-- jump to the nearest node on the adjacent row. Nodes are drawn as icons with no
-- text label, so the focus line has to carry the name itself, and the useful
-- facts are whether the node is already unlocked, whether it CAN be unlocked
-- yet, and whether you can afford it.
--
-- Without that last part the screen is unusable by ear: pressing enter on an
-- unaffordable node simply does nothing.
--
-- Everything else a sighted player gets -- what the node costs in knowledge,
-- which recipes it unlocks, the flavour description, and their own knowledge
-- stock -- is drawn in the hint windows down the side, and is served here through
-- details() on `=`, the same key the item grids use. The state assembles all of
-- it into one `currentNode` table (states/research.lua, updateCurrentNode), so
-- that upvalue is the single place to read rather than reassembling it from
-- models.research, whose `nodes` table is file-local and whose unlock ids are
-- recipe ids rather than the item names the window shows.

local researchModel = require("models.research")

-- The order the game draws the knowledge icons in, so cost and stock read in a
-- stable order rather than pairs() order, which varies between runs.
local knowledgeTypes = {"practical", "ecclesiastic", "academic", "occult"}

-- "alchemy_basics_2" -> "alchemy basics 2". Only a fallback now: currentNode.title
-- is the real name, and this is what is left if the hint has not been built yet.
local function humanise(id)
	return (tostring(id):gsub("_", " "))
end

local function currentNode(stateTable, menus)
	local node = menus.getAnyUpvalue(stateTable, "currentNode")
	if type(node) ~= "table" then
		return nil
	end
	return node
end

-- The player's knowledge stock. Required lazily: models.journal drags in a lot of
-- the game, and a require at load time would run before the game is up.
local function knowledgeStock()
	local ok, journalModel = pcall(require, "models.journal")
	if not ok or type(journalModel) ~= "table" then
		return {}
	end
	return journalModel.knowledge or {}
end

-- "4 practical, 2 occult", in draw order, or nil if the node is free.
local function costPhrase(cost)
	if type(cost) ~= "table" then
		return nil
	end

	local parts = {}
	for _, knowledgeType in ipairs(knowledgeTypes) do
		local amount = cost[knowledgeType]
		if amount and amount > 0 then
			parts[#parts + 1] = amount .. " " .. knowledgeType
		end
	end

	if #parts == 0 then
		return nil
	end

	return table.concat(parts, ", ")
end

return {
	read = function(stateTable, menus)
		local nodeId = menus.getAnyUpvalue(stateTable, "currentNodeId")

		if nodeId == nil then
			return nil, nil
		end

		local node = currentNode(stateTable, menus)
		local parts = {(node and node.title) or humanise(nodeId)}

		local unlocked = researchModel.unlockedNodes and researchModel.unlockedNodes[nodeId]

		if unlocked then
			parts[#parts + 1] = "researched"
		else
			local okUnlockable, unlockable = pcall(researchModel.isUnlockable, nodeId)
			local okAfford, affordable = pcall(researchModel.canAffordNode, nodeId)

			if okUnlockable and not unlockable then
				parts[#parts + 1] = "locked"
			elseif okAfford and not affordable then
				parts[#parts + 1] = "cannot afford"
			else
				parts[#parts + 1] = "available"
			end
		end

		return table.concat(parts, ", "), tostring(nodeId) .. ":" .. tostring(unlocked)
	end,

	-- One block per part of the hint window -- cost, unlocks, description -- so
	-- that [ and ] can walk back through them after the utterance has gone by.
	details = function(stateTable, menus, verbose)
		local node = currentNode(stateTable, menus)
		if not node then
			return nil
		end

		local blocks = {}

		if verbose then
			blocks[#blocks + 1] = node.title or humanise(node.id)
		end

		local unlocked = researchModel.unlockedNodes and researchModel.unlockedNodes[node.id]
		local cost = costPhrase(node.knowledgeCost)

		if unlocked then
			blocks[#blocks + 1] = "Researched already"
		elseif cost then
			-- Say the shortfall, not just the price: "cannot afford" on the focus
			-- line doesn't say by how much, and the stock it is being compared
			-- against is drawn in a separate window the player would otherwise
			-- have to hold in their head.
			local stock = knowledgeStock()
			local missing = {}
			for _, knowledgeType in ipairs(knowledgeTypes) do
				local amount = node.knowledgeCost[knowledgeType]
				if amount and amount > 0 then
					local have = stock[knowledgeType] or 0
					if have < amount then
						missing[#missing + 1] = (amount - have) .. " " .. knowledgeType
					end
				end
			end

			if #missing > 0 then
				blocks[#blocks + 1] = "Costs " .. cost .. " knowledge, short " .. table.concat(missing, ", ")
			else
				blocks[#blocks + 1] = "Costs " .. cost .. " knowledge, affordable"
			end
		else
			blocks[#blocks + 1] = "Costs nothing"
		end

		-- node.unlocks is already the display list the hint window draws under
		-- "Unlocks": the ITEM each recipe produces, named for display.
		if type(node.unlocks) == "table" and #node.unlocks > 0 then
			local names = {}
			for _, unlock in ipairs(node.unlocks) do
				names[#names + 1] = unlock.title or "?"
			end
			blocks[#blocks + 1] = "Unlocks " .. table.concat(names, ", ")
		end

		if node.description then
			blocks[#blocks + 1] = node.description
		end

		-- Verbose only: the whole knowledge purse, including types this node does
		-- not want. Worth having when planning, noise the rest of the time.
		if verbose then
			local stock = knowledgeStock()
			local held = {}
			for _, knowledgeType in ipairs(knowledgeTypes) do
				held[#held + 1] = (stock[knowledgeType] or 0) .. " " .. knowledgeType
			end
			blocks[#blocks + 1] = "Knowledge available, " .. table.concat(held, ", ")
		end

		if #blocks == 0 then
			return nil
		end

		return blocks
	end,
}