fileview.py

import os
import supervisor
from sys import implementation
try:
    from pydos_ui import Pydos_ui
except:
    Pydos_ui = None
    from sys import stdin
try:
    from pydos_ui import input
except:
    pass
#import uselect

def viewFile(args,scrsiz=()):
    # scrsiz can be used if running program from REPL to specify the screen dimensions
    # first import launches with defaults but subsequent launches can use:
    # fileview.viewFile("filename.txt",(height,width))

    def chkPath(tstPath):
        validPath = True
        simpPath = ""

        if tstPath != []:
            savDir = os.getcwd()

            for path in tstPath:
                if path == "":
                    os.chdir("/")
                elif os.getcwd() == "/" and path == "..":
                    validPath = False
                    break
                elif path == ".":
                    continue
                elif path == ".." and len(os.getcwd().split('/')) == 2:
                    os.chdir('/')
                elif path == "..":
                    os.chdir("..")
                elif path in os.listdir() and (os.stat(path)[0] & (2**15) == 0):
                    os.chdir(path)
                else:
                    validPath = False
                    simpPath = ""
                    break

            if validPath:
                simpPath = os.getcwd()
            os.chdir(savDir)

        return((validPath,simpPath))

    def absolutePath(argPath,currDir):

        if argPath[0] == '/':
            fullPath = argPath
        elif currDir == '/':
            fullPath = '/'+argPath
        else:
            fullPath = currDir+'/'+argPath

        if len(fullPath) > 1 and fullPath[-1] == '/':
            fullPath = fullPath[:-1]

        return(fullPath)


    if __name__ == "PyDOS":
        global envVars

        scrLines = int(envVars["_scrHeight"])
        scrWidth = int(envVars["_scrWidth"])
    elif scrsiz:
        (scrLines,scrWidth) = scrsiz
    elif 'get_screensize' in dir(Pydos_ui):
        (scrLines,scrWidth) = Pydos_ui.get_screensize()
    else:
        if 'height' in dir(supervisor.runtime.display):
            scrLines = supervisor.runtime.display.height
            scrWidth = supervisor.runtime.display.width
        else:
            scrLines = 24
            scrWidth = 80

    try:
        type(envVars)
    except:
        envVars={}

    if "_scrollable" in envVars.keys():
        scrollable = (envVars["_scrollable"] == True) or (envVars["_scrollable"] == "True")
    else:
        try:
            scrollable = Pydos_ui.scrollable
        except:
            if implementation.name.upper() == 'CIRCUITPYTHON':
                # Once CircuitPython 9.2.4 is stable this can be change to True
                scrollable = False
            else:
                scrollable = False

    savDir = os.getcwd()
    args = absolutePath(args,savDir)

    aPath = args.split("/")
    newdir = aPath.pop(-1)
    (validPath, tmpDir) = chkPath(aPath)

    if validPath and newdir in os.listdir(tmpDir) and os.stat(tmpDir+("/" if tmpDir[-1] != "/" else "")+newdir)[0] & (2**15) != 0:
        f = open(args)
        index = [0]
        linelengths = []
        scrnMem = []
        currLineNum = 0
        maxRead = 0
        eof = -1
        for i in range(scrLines):
            line = f.readline()
            if line != "":
                index.append(index[i]+len(line))
                scrnMem.append(line[:-1])
                linelengths.append(len(line[:-1]))
                print()
                print((line[:-1])[:scrWidth],end="")
                currLineNum += 1
                maxRead += 1
            else:
                eof = currLineNum
                break

        cmnd = ""
        seqCnt = 0
        strtCol = 0
        while cmnd.upper() != "Q":
            #cmnd = kbdInterrupt()
            if Pydos_ui:
                cmnd = Pydos_ui.read_keyboard(1)
            else:
                cmnd = stdin.read(1)

            if ord(cmnd) == 27 and seqCnt == 0:
                seqCnt = 1
            elif ord(cmnd) == 91 and seqCnt == 1:
                seqCnt = 2
            elif ord(cmnd) == 65 and seqCnt == 2:
                # Up Arrow
                seqCnt = 0
                if currLineNum > scrLines:
                    currLineNum -= 1
                    print (chr(27)+"[1;1H",end="")
                    #print (chr(27)+"[2;0H"+chr(27)+"[T",end="")
                    f.seek(index[currLineNum-scrLines])
                    line = f.readline()
                    scrnMem.pop()
                    scrnMem.insert(0,line[:-1])
                    linelengths.pop()
                    linelengths.insert(0,len(line[:-1]))
                    if not scrollable:
                        #cret = chr(27)+"[H"
                        cret = " "*scrWidth+chr(8)*scrWidth
                        print(cret+((line[:-1])[strtCol:scrWidth+strtCol]),end="")
                        cret = "\n"+(" "*scrWidth)+chr(8)*scrWidth
                        for line in scrnMem[1:]:
                            print(cret+line[strtCol:scrWidth+strtCol],end="")
                            #cret = "\n"
                    else:
                        print((chr(27)+"M")+(line[:-1])[strtCol:scrWidth+strtCol],end="")

            elif ord(cmnd) == 66 and seqCnt == 2:
                # Down Arrow
                seqCnt = 0
                if eof == -1 or currLineNum < eof:
                    f.seek(index[currLineNum])
                    line = f.readline()
                    if line != "":
                        if currLineNum == maxRead:
                            index.append(index[currLineNum]+len(line))
                            maxRead += 1

                        if not scrollable:
                            cret = chr(27)+"[1;1H"+(" "*scrWidth)+chr(8)*scrWidth
                            for _ in scrnMem[1:]:
                                print(cret+_[strtCol:scrWidth+strtCol],end="")
                                cret = "\n"+(" "*scrWidth)+chr(8)*scrWidth

                            print(chr(27)+"["+str(scrLines)+";1H"+chr(8)+(" "*scrWidth)+chr(8)*scrWidth,end="")
                        else:
                            print(chr(27)+"["+str(scrLines)+";1H"+chr(27)+"D",end="")
                        #print(chr(27)+"["+str(scrLines+1)+";0H"+chr(27)+"[S",end="")
                        print((line[:-1])[strtCol:scrWidth+strtCol],end="")
                        scrnMem.pop(0)
                        scrnMem.append(line[:-1])
                        linelengths.pop(0)
                        linelengths.append(len(line[:-1]))
                        currLineNum += 1
                    else:
                        eof = currLineNum

            elif ord(cmnd) == 67 and seqCnt == 2:
                # Right Arrow
                seqCnt = 0
                if max(linelengths) > scrWidth+strtCol:
                    strtCol += 1
                    cret = chr(27)+"[1;1H"
                    for line in scrnMem:
                        if scrWidth+strtCol > len(line.rstrip()):
                            print(cret+line[strtCol:len(line.rstrip())]+" ",end="")
                        else:
                            print(cret+line[strtCol:scrWidth+strtCol],end="")
                        cret = "\n"

            elif ord(cmnd) == 68 and seqCnt == 2:
                # Left Arrow
                seqCnt = 0
                if strtCol > 0:
                    strtCol -= 1
                    cret = chr(27)+"[1;1H"
                    for line in scrnMem:
                        print(cret+line[strtCol:scrWidth+strtCol],end="")
                        cret = "\n"

            else:
                seqCnt = 0


        print(chr(27)+"["+str(scrLines)+";1H",end="")
        f.close()

        del index
        del linelengths
        del scrnMem

    else:
        print("Unable to display: "+args+". File not found.")

if __name__ != "PyDOS":
    passedIn = ""

if passedIn == "":
    passedIn = input("Enter filename:")

viewFile(passedIn)