less Unix Command (ComputerCraft)

--[[
    'less' Unix command
    by EldidiStroyrr

    Prints the contents of a file, either on the hard drive, or from URL.
    Can also dump contents to another file, which makes it kinda like wget.

    pastebin get en8GA73P less
    std pb en8GA73P less
    std ld less less
--]]

local tArg = {...}
local programName = fs.getName(shell.getRunningProgram())

local oldbgcolor, oldtxtcolor = term.getBackgroundColor(), term.getTextColor()

local displayHelp = function(verbose)
    print(programName.." [-a] [-u <url>] [-d/-D <dumped file>] <file>")
    if verbose then
        print([[
Use UP/DOWN arrow keys or mousewheel to scroll, and press X to exit.
Hold LCTRL to alternate scrolling up/down and left/right with mouse wheel.
-h, -v, -help
-a (Uses absolute path)
-u (Downloads a URL and uses that)
-d (Dumps to file. Overwrites)
-D (Dumps to file. Appends)
        ]])
    else
        print("Do -v for verbose help.")
    end
end

if not tArg[1] then
    displayHelp(false)
    return false
elseif tArg[1] == "-help" or tArg[1] == "-h" or tArg[1] == "-v" then
    displayHelp(true)
    return true
end

local renderTable = function(tab, start, ending, rightscroll, txtcolor, bgcolor)
    term.setCursorPos(1,1)
    local buffer = ""
    local scr_x, scr_y = term.getSize()
    term.setTextColor(txtcolor)
    term.setBackgroundColor(bgcolor)
    term.clear()
    local bezelSize = #tostring(#tab)
    for a = start,ending do
        if tab[a] then
            term.setTextColor(colors.black)
            term.setBackgroundColor(colors.lightGray)
            local bezel = tostring(a)
            local bezel = bezel..string.rep(" ",bezelSize-#bezel)
            write(bezel)
            term.setTextColor(txtcolor)
            term.setBackgroundColor(bgcolor)
            write( string.sub(buffer..tab[a],rightscroll+1,rightscroll+scr_x-bezelSize) )
            if a ~= ending then
                write("\n")
            end
        else
            term.setBackgroundColor(colors.lightGray)
            term.clearLine()
        end
    end
end

local tableFind = function(tab, str)
    for a = 1, #tab do
        if tab[a] == str then
            return true, a
        end
    end
    return false
end

local tableStringFind = function(tab, str)
    local output = {}
    for a = 1, #tab do
        local finder = {string.find(tab[a],str)}
        if finder ~= {} then
            table.insert(finder,a)
            table.insert(output,finder)
        end
    end
    return output
end

local function displayCredits()
    local credits = {
        "LESS unix command",
        "programmed by",
        "EldidiStroyrr",
        "",
        "Coding started at",
        "January 1st, 2016",
        "",
        "For normal CC1.7x computers, you're",
        "good to go!",
    }
    term.setBackgroundColor(colors.gray)
    if term.isColor() then term.setTextColor(colors.yellow) else term.setTextColor(colors.white) end
    term.clear()
    local scr_x, scr_y = term.getSize()
    for a = 1, #credits+12 do
        local msg = credits[a/2]
        if a % 2 == 0 and msg then
            term.setCursorPos((scr_x/2)-(#msg/2),scr_y)
            write(string.upper(msg))
        end
        sleep(0.4)
        term.scroll(1)
    end
    term.setBackgroundColor(colors.black)
    term.clear()
    term.setCursorPos(1,1)
    return "butts"
end

local getTableFromFile = function(filename)
    if not filename then
        return false
    end
    if not fs.exists(filename) then
        return false
    end
    local file = fs.open(filename,"r")
    local line = ""
    local output = {}
    while line do
        line = file.readLine()
        table.insert(output,line)
    end
    file.close()
    return output
end

local switches = {}
for a = 1, #tArg do
    if string.sub(tArg[a],1,1) == "-" then
        table.insert(switches,string.sub(tArg[a],2,2))
    end
end

local lessfile
local tArgFileNo = 1
local dumpFile = nil

if tableFind(tArg,"Eldeedoo") and fs.exists("Eldeedoo") then
    displayCredits()
    term.setBackgroundColor(colors.black)
    term.setTextColor(colors.red)
    term.clear()
    term.setCursorPos(1,1)
    for a = 1, 4096 do
        write("H")
        write("A")
        if a % 32 == 0 then sleep(0) end
    end
    term.setTextColor(colors.white)
    term.clear()
    term.setCursorPos(1,1)
    print("What a bad dream!")
    if term.isColor() then term.setTextColor(colors.yellow) end
    write("> ")
    term.setTextColor(colors.white)
    sleep(0.1)
    term.setCursorBlink(true)
    os.pullEventRaw("key")
    if term.isColor() then term.setTextColor(colors.red) end
    term.setCursorPos(1,2)
    print("AND YOU'RE NEVER WAKING UP!!")
    term.setTextColor(colors.white)
    sleep(0)
    return "I like Undertale too much..."
end

if tableFind(tArg,"-d") or tableFind(tArg,"-D") then
    local _, dumpPos
    if tableFind(tArg,"-d") then
        _, dumpPos = tableFind(tArg,"-d")
        dumpPos = dumpPos + 1
    else
        _, dumpPos = tableFind(tArg,"-D")
        dumpPos = dumpPos + 1
    end
    dumpFile = tArg[dumpPos]
    if fs.isReadOnly(dumpFile) then
        error("That path is read only.")
    end
    tArgFileNo = tArgFileNo + 2
    if tableFind(tArg,"-a") then
        lessfile = tArg[tArgFileNo]
    else
        lessfile = fs.combine(shell.dir(),tArg[tArgFileNo])
    end
end
if tableFind(tArg,"-u") then
    local _, urlPos = tableFind(tArg,"-u")
    urlPos = urlPos + 1
    local url = tArg[urlPos]
    tArgFileNo = tArgFileNo + 2
    write("Connecting...")
    local internetFile = http.get(url)
    if not internetFile then
        print("FAILED!")
    end
    internetFile = internetFile.readAll()
    if #internetFile > fs.getFreeSpace("/") then --1 byte for every character, plus one
        error("You don't have enough space!")
    end
    local file = fs.open(".temp","w")
    file.write(internetFile)
    file.close()
    lessfile = ".temp"
else
    lessfile = tArg[tArgFileNo]
end

if not fs.exists(lessfile) then
    error("'"..lessfile.."' does not exist!")
elseif fs.isDir(lessfile) then
    printError("That.")
    sleep(0.3)
    printError("Is a directory.")
    return false
end

if dumpFile then
    local file
    if tableFind(tArg,"-d") then
        file = fs.open(dumpFile,"w")
        print("Dumped to '"..dumpFile.."'")
    else
        file = fs.open(dumpFile,"a")
        print("Appended to '"..dumpFile.."'")
    end
    local file2 = fs.open(lessfile,"r")
    file.write(file2.readAll())
    file.close()
    file2.close()
    return true
end

local lessfilecontents = getTableFromFile(lessfile)
local longestStringLen = 0
for a = 1, #lessfilecontents do
    if #lessfilecontents[a] > longestStringLen then
        longestStringLen = #lessfilecontents[a]
    end
end

local scr_x, scr_y = term.getSize()
local scrollX, scrollY = 0, 0
local event, var1, var2, var3

local function draw()
    renderTable(lessfilecontents,scrollY+1,scrollY+scr_y,scrollX,colors.white,colors.gray)
end

draw()

local allInput = function()
    local alternateScroll = false
    local scr_x, scr_y = term.getSize()
    local lineHistory = {}
    while true do
        repeat
            event, var1, var2, var3 = os.pullEvent()
        until event == "key" or event == "char" or event == "mouse_scroll" or event == "key_up"
        oldScrollX, oldScrollY = scrollX, scrollY
        if event == "key" or event == "char" then
            if var1 == 38 then --'l' to go to line
                term.setCursorPos(1,1)
                term.setBackgroundColor(colors.black)
                term.setTextColor(colors.white)
                term.clearLine()
                write("Goto line: ")
                sleep(0)
                local lineno = tonumber(read(nil,lineHistory))
                if lineno then
                    term.setCursorPos(1,1)
                    if lineno < 1 then
                        write("Huh? Line "..tostring(lineno).."??")
                        sleep(1.2)
                    elseif lineno > #lessfilecontents then
                        write("Too high a number! (lines="..#lessfilecontents..")")
                        sleep(1.2)
                    else
                        table.insert(lineHistory)
                        scrollY = lineno-1 or 1
                    end
                end
                draw()
            end
            if var1 == 200 or var1 == 21 then --up arrow or 'y'
                if scrollY > 0 then
                    scrollY = scrollY - 1
                end
            elseif var1 == 208 or var1 == 18 then --down arrow or 'e'
                if scrollY < #lessfilecontents-1 then
                    scrollY = scrollY + 1
                end
            elseif var1 == 21 then --'u'
                if scrollY-math.floor(scr_y/2) > 0 then
                    scrollY = scrollY - math.floor(scr_y/2)
                end
            elseif var1 == 18 then --'d'
                if scrollY+math.floor(scr_y/2) < #lessfilecontents-1 then
                    scrollY = scrollY + math.floor(scr_y/2)
                end
            elseif var1 == 203 then --left arrow
                if scrollX > 0 then
                    scrollX = scrollX - 1
                end
            elseif var1 == 205 then --right arrow
                if scrollX < longestStringLen then
                    scrollX = scrollX + 1
                end
            end
            if var1 == 45 or var1 == 16 then --'X' or 'Q' to quit
                sleep(0)
                break
            end
            if var1 == 29 then --left ctrl
                alternateScroll = true
            end
            if var1 == 199 or var1 == "g" then --home
                scrollY = 0
            end
            if var1 == 207 or var1 == "G" then --end
                scrollY = #lessfilecontents-scr_y
            end
            if var1 == 201 or var1 == "b" then --page up
                scrollY = scrollY - scr_y
                if scrollY < 0 then scrollY = 0 end
            end
            if var1 == 209 or var1 == "f" then --page down
                scrollY = scrollY + scr_y
                if scrollY > #lessfilecontents-1 then scrollY = #lessfilecontents-1 end
            end
        elseif event == "mouse_scroll" then
            if not alternateScroll then
                if var1 == -1 then
                    if scrollY > 0 then
                        scrollY = scrollY - 1
                    end
                elseif var1 == 1 then
                    if scrollY < #lessfilecontents-1 then
                        scrollY = scrollY + 1
                    end
                end
            else
                if var1 == -1 then
                    if scrollX > 0 then
                        scrollX = scrollX - 1
                    end
                elseif var1 == 1 then
                    if scrollX < longestStringLen then
                        scrollX = scrollX + 1
                    end
                end
            end
        elseif event == "key_up" then
            if var1 == 29 then --left ctrl
                alternateScroll = false
            end
        end
        if scrollX ~= oldScrollX or scrollY ~= oldScrollY then --Yay flicker reduction
            draw()
        end
    end
end

allInput()

term.setBackgroundColor(oldbgcolor)
term.setTextColor(oldtxtcolor)
term.clear()
term.setCursorPos(1,1)