--[[
Itemscript - A simplified set of methods for item manipulation.

Author: Andrew Lalis <andrewlalisofficial@gmail.com>


]]--
VERSION = "0.0.1"

local t = turtle

-- The itemscript module. Functions defined within this table are exported.
local itemscript = {}

-- Determines if an item stack matches the given name.
-- If fuzzy, then the item name will be matched against the given name.
local function stackMatches(itemStack, name, fuzzy)
    return itemStack ~= nil and
        (
            (not fuzzy and itemStack.name == name) or
            string.find(itemStack.name, name)
        )
end

-- Creates a filter function that filters on items whose names match the given list of names.
local function makeItemNamesFilter(names, fuzzy)
    return function(item)
        for _, itemName in pairs(names) do
            if stackMatches(item, itemName, fuzzy) then
                return true
            end
        end
        return false
    end
end

local function notFilter(filter)
    return function(item)
        return not filter(item)
    end
end

local function andFilter(filters)
    return function(item)
        for _, filter in pairs(filters) do
            if not filter(item) then
                return false
            end
        end
        return true
    end
end

local function orFilter(filters)
    return function(item)
        for _, filter in pairs(filters) do
            if filter(item) then
                return true
            end
        end
        return false
    end
end

-- Parses a filter expression string and returns a filter that implements it.
--[[
    Item Filter Expressions:
    
    A filter expression is a way to define a complex method of matching item
    stacks.

    Prepending ! will match any item stack whose name does not match.
    Prepending # will do a fuzzy match using string.find.
]]--
local function parseItemFilterExpression(expr)
    local prefixIdx, prefixIdxEnd = string.find(expr, "^[!#]+")
    local fuzzy = false
    local negated = false
    if prefixIdx ~= nil then
        for i = prefixIdx, prefixIdxEnd do
            if expr[i] == "!" then
                negated = true
            elseif expr[i] == "#" then
                fuzzy = true
            end
        end
        expr = string.sub(expr, prefixIdxEnd + 1, string.len(expr))
    end
    local namespaceSeparatorIdx = string.find(expr, ":")
    if namespaceSeparatorIdx == nil and not fuzzy then
        expr = "minecraft:" .. expr
    end
    local filter = makeItemNamesFilter({expr}, fuzzy)
    if negated then
        filter = notFilter(filter)
    end
    return filter
end

-- Converts an arbitrary variable into a filter; useful for any function that's public, so users can supply any filter.
-- It converts the following:
-- filter function tables directly.
-- strings and lists of strings are translated into an item names filter.
-- Functions are added with default fuzzy and whitelist parameters.
local function convertToFilter(var)
    if type(var) == "table" and #var > 0 and type(var[1]) == "string" then
        local filters = {}
        for _, expr in pairs(var) do
            table.insert(filters, parseItemFilterExpression(expr))
        end
        return orFilter(filters)
    elseif type(var) == "string" then
        return parseItemFilterExpression(var)
    elseif type(var) == "function" then
        return var
    else
        error("Unsupported filter type: " .. type(var))
    end
end

-- Convenience function for creating a filter function that allows specifying fuzziness.
function itemscript.nameFilter(name, fuzzy)
    return makeItemNamesFilter({name}, fuzzy)
end

-- Gets the total number of items in the turtle's inventory that match the given expression.
function itemscript.totalCount(filterExpr)
    local filter = convertToFilter(filterExpr)
    local count = 0
    for i = 1, 16 do
        local item = t.getItemDetail(i)
        if filter(item) then
            count = count + item.count
        end
    end
    return count
end

-- Selects a slot containing at least one of the given item type.
-- Returns a boolean indicating whether we could find and select the item.
function itemscript.select(filterExpr)
    local filter = convertToFilter(filterExpr)
    for i = 1, 16 do
        local item = t.getItemDetail(i)
        if filter(item) then
            t.select(i)
            return true
        end
    end
    return false
end

-- Helper function to drop items in a flexible way, using a drop function and filtering function.
local function dropFiltered(dropFunction, filter)
    for i = 1, 16 do
        local item = t.getItemDetail(i)
        if filter(item) then
            t.select(i)
            dropFunction()
        end
    end
end

function itemscript.dropAll(filterExpr)
    dropFiltered(t.drop, convertToFilter(filterExpr))
end

function itemscript.dropAllDown(filterExpr)
    dropFiltered(t.dropDown, convertToFilter(filterExpr))
end

function itemscript.dropAllUp(filterExpr)
    dropFiltered(t.dropUp, convertToFilter(filterExpr))
end

-- Cleans up the turtle's inventory by compacting all stacks of items.
function itemscript.organize()
    error("Not yet implemented.")
end

return itemscript