-- lib/itemDB.lua — Item display name database
-- Learns display names from getItemDetail() and persists to disk.
-- Adapted from opus-apps core.itemDB for Inventory Manager.
--
-- Usage:
--   local itemDB = dofile("lib/itemDB.lua")
--   itemDB.init(".item_names.db")
--   itemDB.learn("minecraft:diamond", "Diamond")
--   print(itemDB.getName("minecraft:diamond"))  --> "Diamond"

local itemDB = {}

local nameData = {}
local DATA_FILE = nil
local dirty = false

-------------------------------------------------
-- Initialization and persistence
-------------------------------------------------

function itemDB.init(dataFile)
    DATA_FILE = dataFile
    itemDB.load()
end

function itemDB.load()
    if not DATA_FILE or not fs.exists(DATA_FILE) then return end
    pcall(function()
        local f = fs.open(DATA_FILE, "r")
        local raw = f.readAll()
        f.close()
        local data = textutils.unserialise(raw)
        if type(data) == "table" then
            nameData = data
        end
    end)
end

function itemDB.flush()
    if not dirty or not DATA_FILE then return end
    pcall(function()
        local f = fs.open(DATA_FILE, "w")
        f.write(textutils.serialise(nameData))
        f.close()
    end)
    dirty = false
end

-------------------------------------------------
-- Name resolution
-------------------------------------------------

--- Get a human-readable display name for an item.
-- Falls back to generating a name from the item ID.
-- @param itemName  string or table with .name field
-- @return string
function itemDB.getName(itemName)
    if type(itemName) == "table" then itemName = itemName.name end
    if not itemName then return "?" end
    if nameData[itemName] then return nameData[itemName] end
    -- Generate readable name from item ID (e.g. "minecraft:iron_ingot" -> "Iron Ingot")
    local short = itemName:gsub("^[%w_]+:", "")
    return short:gsub("_", " "):gsub("(%a)([%w_']*)", function(first, rest)
        return first:upper() .. rest:lower()
    end)
end

--- Learn a display name for an item.
-- @param itemName     string or table with .name and optional .displayName
-- @param displayName  string (optional if itemName is a table)
function itemDB.learn(itemName, displayName)
    if type(itemName) == "table" then
        displayName = displayName or itemName.displayName
        itemName = itemName.name
    end
    if itemName and displayName and displayName ~= "" then
        if nameData[itemName] ~= displayName then
            nameData[itemName] = displayName
            dirty = true
        end
    end
end

--- Learn from a getItemDetail() result table.
-- @param detail  table with .name and .displayName fields
function itemDB.learnFromDetail(detail)
    if detail and detail.name and detail.displayName then
        itemDB.learn(detail.name, detail.displayName)
    end
end

-------------------------------------------------
-- Queries
-------------------------------------------------

--- Check if an item's display name has been learned.
function itemDB.isKnown(itemName)
    if type(itemName) == "table" then itemName = itemName.name end
    return nameData[itemName] ~= nil
end

--- Get all known name mappings.
function itemDB.getAllNames()
    return nameData
end

--- Get count of known items.
function itemDB.count()
    local n = 0
    for _ in pairs(nameData) do n = n + 1 end
    return n
end

return itemDB