Custom Edit For ComputerCraft

-- Get file to edit
local tArgs = { ... }
if #tArgs == 0 then
        print( "Usage: edit <path>" )
        return
end

-- Error checking
local sPath = shell.resolve( tArgs[1] )
local bReadOnly = fs.isReadOnly( sPath )
if fs.exists( sPath ) and fs.isDir( sPath ) then
        print( "Cannot edit a directory." )
        return
end

local x,y = 1,1
local w,h = term.getSize()
local scrollX, scrollY = 0,0

local tLines = {}
bRunning = true

-- Colours
local highlightColour, keywordColour, commentColour, textColour, bgColour
if term.isColour() then
        bgColour = colours.black
        textColour = colours.white
        highlightColour = colours.yellow
        keywordColour = colours.yellow
        commentColour = colours.green
        stringColour = colours.red
else
        bgColour = colours.black
        textColour = colours.white
        highlightColour = colours.white
        keywordColour = colours.white
        commentColour = colours.white
        stringColour = colours.white
end

-- Menus
local bMenu = false
local nMenuItem = 1
local tMenuItems
if bReadOnly then
        tMenuItems = { "Exit", "Print" }
else
        tMenuItems = { "Save", "Exit", "Print" }
end

local sStatus = "Press Ctrl to access menu"

local function load( _sPath )
        tLines = {}
        if fs.exists( _sPath ) then
                local file = io.open( _sPath, "r" )
                local sLine = file:read()
                while sLine do
                        table.insert( tLines, sLine )
                        sLine = file:read()
                end
                file:close()
        end

        if #tLines == 0 then
                table.insert( tLines, "" )
        end
end

local function save( _sPath )
        -- Create intervening folder
        local sDir = sPath:sub(1, sPath:len() - fs.getName(sPath):len() )
        if not fs.exists( sDir ) then
                fs.makeDir( sDir )
        end

        -- Save
        local file = nil
        local function innerSave()
                file = fs.open( _sPath, "w" )
                if file then
                        for n, sLine in ipairs( tLines ) do
                                file.write( sLine .. "\n" )
                        end
                else
                        error( "Failed to open ".._sPath )
                end
        end

        local ok = pcall( innerSave )
        if file then
                file.close()
        end
        return ok
end

local tKeywords = {
        ["and"] = true,
        ["break"] = true,
        ["do"] = true,
        ["else"] = true,
        ["elseif"] = true,
        ["end"] = true,
        ["false"] = true,
        ["for"] = true,
        ["function"] = true,
        ["if"] = true,
        ["in"] = true,
        ["local"] = true,
        ["nil"] = true,
        ["not"] = true,
        ["or"] = true,
        ["repeat"] = true,
        ["return"] = true,
        ["then"] = true,
        ["true"] = true,
        ["until"]= true,
        ["while"] = true,
        ["os"] = true,
        ["fs"] = true,
        ["io"] = true,
        ["colors"] = true,
        ["colours"] = true,
        ["parallel"] = true,
        ["term"] = true,
        ["shell"] = true,
        ["redstone"] = true,
        ["rs"] = true,
        ["http"] = true,
        ["rednet"] = true,
        ["textutils"] = true,
        ["math"] = true,
        ["disk"] = true,
        ["table"] = true,
        ["coroutine"] = true,
        ["bit"] = true,
        ["help"] = true,
        ["string"] = true,
}

local function tryWrite( sLine, regex, colour )
        local match = string.match( sLine, regex )
        if match then
                if type(colour) == "number" then
                        term.setTextColour( colour )
                else
                        term.setTextColour( colour(match) )
                end
                term.write( match )
                term.setTextColour( textColour )
                return string.sub( sLine, string.len(match) + 1 )
        end
        return nil
end

local function writeHighlighted( sLine )
        while string.len(sLine) > 0 do
                sLine =
                        tryWrite( sLine, "^%-%-%[%[.-%]%]", commentColour ) or
                        tryWrite( sLine, "^%-%-.*", commentColour ) or
                        tryWrite( sLine, "^\".-[^\\]\"", stringColour ) or
                        tryWrite( sLine, "^\'.-[^\\]\'", stringColour ) or
                        tryWrite( sLine, "^%[%[.-%]%]", stringColour ) or
                        tryWrite( sLine, "^[%w_]+", function( match )
                                if tKeywords[ match ] then
                                        return keywordColour
                                end
                                return textColour
                        end ) or
                        tryWrite( sLine, "^[^%w_]", textColour )
        end
end

local function redrawText()
        for y=1,h-1 do
                term.setCursorPos( 1 - scrollX, y )
                term.clearLine()

                local sLine = tLines[ y + scrollY ]
                if sLine ~= nil then
                        writeHighlighted( sLine )
                end
        end
        term.setCursorPos( x - scrollX, y - scrollY )
end

local function redrawLine(_nY)
        local sLine = tLines[_nY]
        term.setCursorPos( 1 - scrollX, _nY - scrollY )
        term.clearLine()
        writeHighlighted( sLine )
        term.setCursorPos( x - scrollX, _nY - scrollY )
end

local function redrawMenu()
    -- Clear line
    term.setCursorPos( 1, h )
        term.clearLine()

    -- Draw line numbers
    term.setCursorPos( w - string.len( "Ln "..y ) + 1, h )
    term.setTextColour( highlightColour )
    term.write( "Ln " )
    term.setTextColour( textColour )
    term.write( y )

    term.setCursorPos( 1, h )
        if bMenu then
        -- Draw menu
                term.setTextColour( textColour )
                for nItem,sItem in pairs( tMenuItems ) do
                        if nItem == nMenuItem then
                                term.setTextColour( highlightColour )
                                term.write( "[" )
                                term.setTextColour( textColour )
                                term.write( sItem )
                                term.setTextColour( highlightColour )
                                term.write( "]" )
                        term.setTextColour( textColour )
                        else
                                term.write( " "..sItem.." " )
                        end
                end
    else
        -- Draw status
        term.setTextColour( highlightColour )
        term.write( sStatus )
        term.setTextColour( textColour )
    end

        -- Reset cursor
        term.setCursorPos( x - scrollX, y - scrollY )
end

local tMenuFuncs = {
        Save=function()
                if bReadOnly then
                        sStatus = "Access denied"
                else
                        local ok, err = save( sPath )
                        if ok then
                                sStatus="Saved to "..sPath
                        else
                                sStatus="Error saving to "..sPath
                        end
                end
                redrawMenu()
        end,
        Print=function()
                local printer = peripheral.find( "printer" )
                if not printer then
                        sStatus = "No printer attached"
                        return
                end

                local nPage = 0
                local sName = fs.getName( sPath )
                if printer.getInkLevel() < 1 then
                        sStatus = "Printer out of ink"
                        return
                elseif printer.getPaperLevel() < 1 then
                        sStatus = "Printer out of paper"
                        return
                end

                local screenTerminal = term.current()
                local printerTerminal = {
                        getCursorPos = printer.getCursorPos,
                        setCursorPos = printer.setCursorPos,
                        getSize = printer.getPageSize,
                        write = printer.write,
                }
                printerTerminal.scroll = function()
                        if nPage == 1 then
                                printer.setPageTitle( sName.." (page "..nPage..")" )
                        end

                        while not printer.newPage()     do
                                if printer.getInkLevel() < 1 then
                                        sStatus = "Printer out of ink, please refill"
                                elseif printer.getPaperLevel() < 1 then
                                        sStatus = "Printer out of paper, please refill"
                                else
                                        sStatus = "Printer output tray full, please empty"
                                end

                                term.redirect( screenTerminal )
                                redrawMenu()
                                term.redirect( printerTerminal )

                                local timer = os.startTimer(0.5)
                                sleep(0.5)
                        end

                        nPage = nPage + 1
                        if nPage == 1 then
                                printer.setPageTitle( sName )
                        else
                                printer.setPageTitle( sName.." (page "..nPage..")" )
                        end
                end

                bMenu = false
                term.redirect( printerTerminal )
                local ok, error = pcall( function()
                        term.scroll()
                        for n, sLine in ipairs( tLines ) do
                                print( sLine )
                        end
                end )
        term.redirect( screenTerminal )
                if not ok then
                        print( error )
                end

                while not printer.endPage() do
                        sStatus = "Printer output tray full, please empty"
                        redrawMenu()
                        sleep( 0.5 )
                end
                bMenu = true

                if nPage > 1 then
                        sStatus = "Printed "..nPage.." Pages"
                else
                        sStatus = "Printed 1 Page"
                end
                redrawMenu()
        end,
        Exit=function()
                bRunning = false
        end
}

local function doMenuItem( _n )
        tMenuFuncs[tMenuItems[_n]]()
        if bMenu then
                bMenu = false
                term.setCursorBlink( true )
        end
        redrawMenu()
end

local function setCursor( x, y )
        local screenX = x - scrollX
        local screenY = y - scrollY

        local bRedraw = false
        if screenX < 1 then
                scrollX = x - 1
                screenX = 1
                bRedraw = true
        elseif screenX > w then
                scrollX = x - w
                screenX = w
                bRedraw = true
        end

        if screenY < 1 then
                scrollY = y - 1
                screenY = 1
                bRedraw = true
        elseif screenY > h-1 then
                scrollY = y - (h-1)
                screenY = h-1
                bRedraw = true
        end

        if bRedraw then
                redrawText()
        end
        term.setCursorPos( screenX, screenY )

        -- Statusbar now pertains to menu, it would probably be safe to redraw the menu on every key event.
        redrawMenu()
end

-- Actual program functionality begins
load(sPath)

term.setBackgroundColour( bgColour )
term.clear()
term.setCursorPos(x,y)
term.setCursorBlink( true )

redrawText()
redrawMenu()

-- Handle input
while bRunning do
        local sEvent, param, param2, param3 = os.pullEvent()
        if sEvent == "key" then
                if param == keys.up then
                        -- Up
                        if not bMenu then
                                if y > 1 then
                                        -- Move cursor up
                                        y = y - 1
                                        x = math.min( x, string.len( tLines[y] ) + 1 )
                                        setCursor( x, y )
                                end
                        end
                elseif param == keys.down then
                        -- Down
                        if not bMenu then
                                -- Move cursor down
                                if y < #tLines then
                                        y = y + 1
                                        x = math.min( x, string.len( tLines[y] ) + 1 )
                                        setCursor( x, y )
                                end
                        end
                elseif param == keys.tab then
                        -- Tab
                        if not bMenu and not bReadOnly then
                                -- Indent line
                                tLines[y]="  "..tLines[y]
                                x = x + 2
                                setCursor( x, y )
                                redrawLine(y)
                        end
                elseif param == keys.pageUp then
                        -- Page Up
                        if not bMenu then
                                -- Move up a page
                                if y - (h - 1) >= 1 then
                                        y = y - (h - 1)
                                else
                                        y = 1
                                end
                                x = math.min( x, string.len( tLines[y] ) + 1 )
                                setCursor( x, y )
                        end
                elseif param == keys.pageDown then
                        -- Page Down
                        if not bMenu then
                                -- Move down a page
                                if y + (h - 1) <= #tLines then
                                        y = y + (h - 1)
                                else
                                        y = #tLines
                                end
                                x = math.min( x, string.len( tLines[y] ) + 1 )
                                setCursor( x, y )
                        end
                elseif param == keys.home then
                        -- Home
                        if not bMenu then
                                -- Move cursor to the beginning
                                x=1
                                setCursor(x,y)
                        end
                elseif param == keys["end"] then
                        -- End
                        if not bMenu then
                                -- Move cursor to the end
                                x = string.len( tLines[y] ) + 1
                                setCursor(x,y)
                        end
                elseif param == keys.left then
                        -- Left
                        if not bMenu then
                                if x > 1 then
                                        -- Move cursor left
                                        x = x - 1
                                elseif x==1 and y>1 then
                                        x = string.len( tLines[y-1] ) + 1
                                        y = y - 1
                                end
                                setCursor( x, y )
                        else
                                -- Move menu left
                                nMenuItem = nMenuItem - 1
                                if nMenuItem < 1 then
                                        nMenuItem = #tMenuItems
                                end
                                redrawMenu()
                        end
                elseif param == keys.right then
                        -- Right
                        if not bMenu then
                                if x < string.len( tLines[y] ) + 1 then
                                        -- Move cursor right
                                        x = x + 1
                                elseif x==string.len( tLines[y] ) + 1 and y<#tLines then
                                        x = 1
                                        y = y + 1
                                end
                                setCursor( x, y )
                        else
                                -- Move menu right
                                nMenuItem = nMenuItem + 1
                                if nMenuItem > #tMenuItems then
                                        nMenuItem = 1
                                end
                                redrawMenu()
                        end
                elseif param == keys.delete then
                        -- Delete
                        if not bMenu and not bReadOnly then
                                if  x < string.len( tLines[y] ) + 1 then
                                        local sLine = tLines[y]
                                        tLines[y] = string.sub(sLine,1,x-1) .. string.sub(sLine,x+1)
                                        redrawLine(y)
                                elseif y<#tLines then
                                        tLines[y] = tLines[y] .. tLines[y+1]
                                        table.remove( tLines, y+1 )
                                        redrawText()
                                        redrawMenu()
                                end
                        end
                elseif param == keys.backspace then
                        -- Backspace
                        if not bMenu and not bReadOnly then
                                if x > 1 then
                                        -- Remove character
                                        local sLine = tLines[y]
                                        tLines[y] = string.sub(sLine,1,x-2) .. string.sub(sLine,x)
                                        redrawLine(y)

                                        x = x - 1
                                        setCursor( x, y )
                                elseif y > 1 then
                                        -- Remove newline
                                        local sPrevLen = string.len( tLines[y-1] )
                                        tLines[y-1] = tLines[y-1] .. tLines[y]
                                        table.remove( tLines, y )
                                        redrawText()

                                        x = sPrevLen + 1
                                        y = y - 1
                                        setCursor( x, y )
                                end
                        end
                elseif param == keys.enter then
                        -- Enter
                        if not bMenu and not bReadOnly then
                                -- Newline
                                local sLine = tLines[y]
                                local _,spaces=string.find(sLine,"^[ ]+")
                                if not spaces then
                                        spaces=0
                                end
                                tLines[y] = string.sub(sLine,1,x-1)
                                table.insert( tLines, y+1, string.rep(' ',spaces)..string.sub(sLine,x) )
                                redrawText()

                                x = spaces+1
                                y = y + 1
                                setCursor( x, y )
                        elseif bMenu then
                                -- Menu selection
                                doMenuItem( nMenuItem )
                        end
                elseif param == keys.leftCtrl or param == keys.rightCtrl then
                        -- Menu toggle
                        bMenu = not bMenu
                        if bMenu then
                                term.setCursorBlink( false )
                        else
                                term.setCursorBlink( true )
                        end
                        redrawMenu()
                end

        elseif sEvent == "char" then
                if not bMenu and not bReadOnly then
                        -- Input text
                        local sLine = tLines[y]
                        tLines[y] = string.sub(sLine,1,x-1) .. param .. string.sub(sLine,x)
                        redrawLine(y)

                        x = x + 1
                        setCursor( x, y )
                elseif bMenu then
                        -- Select menu items
                        for n,sMenuItem in ipairs( tMenuItems ) do
                                if string.lower(string.sub(sMenuItem,1,1)) == string.lower(param) then
                                        doMenuItem( n )
                                        break
                                end
                        end
                end

        elseif sEvent == "paste" then
                if not bMenu and not bReadOnly then
                        -- Input text
                        local sLine = tLines[y]
                        tLines[y] = string.sub(sLine,1,x-1) .. param .. string.sub(sLine,x)
                        redrawLine(y)

                        x = x + string.len( param )
                        setCursor( x, y )
                end

        elseif sEvent == "mouse_click" then
                if not bMenu then
                        if param == 1 then
                                -- Left click
                                local cx,cy = param2, param3
                                if cy < h then
                                        y = math.min( math.max( scrollY + cy, 1 ), #tLines )
                                        x = math.min( math.max( scrollX + cx, 1 ), string.len( tLines[y] ) + 1 )
                                        setCursor( x, y )
                                end
                        end
                end

        elseif sEvent == "mouse_scroll" then
                if not bMenu then
                        if param == -1 then
                                -- Scroll up
                                if scrollY > 0 then
                                        -- Move cursor up
                                        scrollY = scrollY - 1
                                        redrawText()
                                end

                        elseif param == 1 then
                                -- Scroll down
                                local nMaxScroll = #tLines - (h-1)
                                if scrollY < nMaxScroll then
                                        -- Move cursor down
                                        scrollY = scrollY + 1
                                        redrawText()
                                end

                        end
                end

        elseif sEvent == "term_resize" then
            w,h = term.getSize()
        setCursor( x, y )
        redrawMenu()
        redrawText()

        end
end

-- Cleanup
term.clear()
term.setCursorBlink( false )
term.setCursorPos( 1, 1 )