cPrint API (ComputerCraft)

-- +---------------------+------------+---------------------+
-- |                     |            |                     |
-- |                     |   cPrint   |                     |
-- |                     |            |                     |
-- +---------------------+------------+---------------------+

local version = "Version 1.0.1"

-- An API for generating Printed Books via Command Computers.
-- http://www.computercraft.info/forums2/index.php?/topic/25037-cprint-print-books-with-command-computers/

-- ----------------------------------------------------------

local blank1, blank2, colourNum = string.rep(" ", 25), string.rep("f", 25), {}

do
    local hex, counter = "0123456789abcdef", 1

    for i = 1, 16 do
        colourNum[counter] = hex:sub(i, i)
        counter = counter * 2
    end
end

local function safeString(text)
    local newText = {}

    for i = 1, #text do
        local val = text:byte(i)
        newText[i] = (val > 31 and val < 127) and val or 63
    end

    return string.char(unpack(newText))
end

local function printBook(target, count, page)
    local output, display = {"pages:" .. tostring(math.ceil(#page / 21))}, {}
    if page.title ~= " " then display[1] = "Name:\"" .. page.title .. "\"" end
    if page.lore then display[#display + 1] = "Lore:[\"" .. page.lore .. "\"]" end
    if #display > 0 then output[2] = "display:{" .. table.concat(display, ",").. "}" end

    if type(count) ~= "number" then count = 1 end

    for i = 1, #page do
        output[#output + 1] = "line" .. tostring(i - 1) .. ":\"" .. page[i].text:gsub("\"", "\\\"") .. "\""
        output[#output + 1] = "colour" .. tostring(i - 1) .. ":\"" .. page[i].fg .. "\""
    end

    output = "{" .. table.concat(output, ",") .. "}"

    if target then
        commands.give(target, "ComputerCraft:printout", count, 2, output)
    else
        local x, y, z = commands.getBlockPosition()
        if commands.getBlockInfo(x, y + 1, z).name == "minecraft:air" then commands.setblock(x, y + 1, z, "minecraft:chest", commands.getBlockInfo(x, y, z).metadata) end
        commands.setblock(x, y + 2, z, "minecraft:hopper", 0, "replace", "{Items:[{Slot:0,id:4099,Damage:2,Count:"..tostring(count)..",tag:"..output.."}]}")
        sleep(count * 0.5)
        commands.setblock(x, y + 2, z, "minecraft:air")
    end
end

function newPrintableBook(title)
    if title == "" or not title then title = " " end

    local book, page, xPos, yPos, tCol, bCol = {}, {["title"] = title}, 1, 1, colours.black, colours.white
    for i = 1, 21 do page[i] = {["text"] = blank1, ["fg"] = blank2} end

    book.blit = function(text, fgCol)
        if xPos > 25 or xPos + #text - 1 < 1 or yPos < 1 then return end
        if yPos > #page then for i = #page + 1, yPos do page[i] = {["text"] = blank1, ["fg"] = blank2} end end

        text = safeString(text)

        if xPos < 1 then
            text = text:sub(2 - xPos)
            fgCol = fgCol:sub(2 - xPos)
            xPos = 1
        end

        if xPos + #text > 26 then
            text = text:sub(1, 26 - xPos)
            fgCol = fgCol:sub(1, 26 - xPos)
        end

        page[yPos].text = page[yPos].text:sub(1, xPos - 1) .. text .. page[yPos].text:sub(xPos + #text)
        page[yPos].fg = page[yPos].fg:sub(1, xPos - 1) .. fgCol .. page[yPos].fg:sub(xPos + #fgCol)

        xPos = xPos + #text
    end

    book.write = function(text)
        text = tostring(text)
        book.blit(text, string.rep(colourNum[tCol], #text))
    end

    book.clearLine = function()
        page[yPos].text = blank1
    end

    book.clear = function()
        for i = 1, #page do page[i].text = blank1 end
    end

    book.getSize = function()
        return 25, math.huge
    end

    book.setCursorPos = function(x, y)
        xPos, yPos = math.floor(x), math.floor(y)
    end

    book.getCursorPos = function()
        return xPos, yPos
    end

    book.setTextColour = function(col)
        tCol = col
    end
    book.setTextColor = book.setTextColour

    book.setBackgroundColour = function(col)
        bCol = col
    end
    book.setBackgroundColor = book.setBackgroundColour

    book.getTextColour = function()
        return tCol
    end
    book.getTextColor = book.getTextColour

    book.getBackgroundColour = function()
        return bCol
    end
    book.getBackgroundColor = book.getBackgroundColour

    book.isColour = function()
        return true
    end
    book.isColor = book.isColour

    local dummyFunc = function() end
    book.scroll, book.setCursorBlink = dummyFunc, dummyFunc

    book.setLore = function(lore)
        page.lore = lore and tostring(lore)
    end

    book.printBook = function(target, count)
        printBook(target, count, page)
    end

    return book
end