# -*- coding: UTF-8 -*-
'''
rtx - RetroText
rtxHelpers: verschiedene Hilfsfunktionen
by Anna Christina Naß <acn@acn.wtf>
released under GPL
'''

from rtxPage import rtxPage
import cept
import glob
import logging
import config

def process_byte(in_byte):
    """ takes the received byte and processes the command line
    if a new command has been entered, it will call process_command()
    if a short link has been entered, the link_list of the current page will be searched
    and the found target will be sent to process_command()
    """
    instr=str(in_byte, encoding="latin-1")
    
    if config.MODE=="modem":
        logging.debug("> %s < CD: %s", instr, glob.ser.getCD())

    # what to send back to the client
    if instr == cept.INI:
        logging.debug("INI")
        echo_char = "*"
    elif instr == cept.TER:
        logging.debug("TER")
        echo_char = "#"
    else:
        echo_char=instr

    # start of line: clear rest of cmdline
    if len(glob.cmdline) == 0:
        glob.ser.write(bytes(cept.CLEARLINE, "latin-1"))

    # echo the character to the client
    glob.ser.write(bytes(echo_char, "latin-1"))

    glob.cmdline += instr

    # Backspace:
    if instr == cept.BSP:
        glob.cmdline = glob.cmdline[:-1]
        return

    logging.debug("Cmdline: >%s<", glob.cmdline)

    # process links inside the page:
    if ( len(glob.cmdline) == 1 or len(glob.cmdline) == 2 ) and glob.curpage.get_link(glob.cmdline):
        glob.cmdline = cept.INI + glob.curpage.get_link(glob.cmdline) + cept.TER
        process_command(glob.cmdline)
        return

    # reset cmdline:
    if instr == cept.INI and glob.cmdline[-2:] == cept.INI+cept.INI:
        logging.debug("reset cmdline")
        glob.cmdline = ""
        glob.ser.write(bytes(cept.clear_line24, "latin-1"))
        return

    # goto last page:
    if instr == cept.TER and glob.cmdline == cept.INI+cept.TER:
        if glob.prevpage.get_page_id() == -1:
            glob.cmdline = ""
            send_error("Keine vorige Seite vorhanden.")
            return
        glob.cmdline = "" # reset cmdline
        goto_last_page()
        return

    # "Make it so":
    if instr == cept.TER:
        # or instr == cept.SEND or instr == cept.CR:
        logging.info("Kommando: >%s<", glob.cmdline)
        process_command(glob.cmdline)
        return

def process_command(cmd):
    """ processes the given command line
    """

    # reset cmdline
    glob.cmdline = ""

    # process *cmdline#, normally a page-loading command:
    if cmd[0] == cept.INI and cmd[-1:] == cept.TER:
        pgnr = cmd[1:-1]
        check_and_send_page(pgnr, "Die Seite kann nicht gefunden werden.")

    # if only # is entered, either go to the link behind '#'
    # or to the next sub-page (2000a => 2000b) if it exists
    if cmd == cept.TER:
        if glob.curpage.get_link("#"):
            pgnr = glob.curpage.get_link("#")
            check_and_send_page(pgnr, "Die Seite kann nicht gefunden werden.")
        else:
            # check if the next page exists, e.g. 2000a => 2000b
            curid = glob.curpage.get_page_id()
            if curid == -1:
                send_error("Keine n"+ cept.UMLAUT +"achste Seite gefunden.")
            elif str(curid[-1:]).isalpha():
                # aus 2000a 2000b machen:
                nextid = curid[:-1] + chr(ord(curid[-1:])+1)
                check_and_send_page(nextid, "Keine n" + cept.UMLAUT +"achste Seite gefunden.")

    # special commands:
    if cmd == "!1" + cept.TER:
        send_welcome_page()
        return
    if cmd == "!2" + cept.TER:
        glob.ser.write(bytes(cept.init_screen, "latin-1"))
        return

def goto_last_page():
    """ go back to the previous page and make the current page the previous page
    """
    logging.info("Letzte Seite: %s", str(glob.prevpage.get_page_id()))

    # swap prevpage and curpage
    temp = glob.curpage
    glob.curpage = glob.prevpage
    glob.prevpage = temp

    # send the previous page (now curpage) to the client
    send_page(glob.curpage)

def send_welcome_page():
    """ get the btxlogo, make a rtxPage of it and send it to the client """
    glob.curpage = rtxPage()
    glob.curpage.set_page(bytes(cept.btxlogo, "latin-1"))
    send_page(glob.curpage)

def check_and_send_page(pgnr, errormsg):
    """ checks if the page "pgnr" exists
    if yes, it loads it into curpage and sends it to the client
    if not, it sends the error message "errormsg" to the client
    """
    logging.info("suche Seite: >%s<", pgnr)

    if rtxPage.exists(pgnr):
        glob.prevpage = glob.curpage
        glob.curpage = rtxPage(pgnr)
        send_page(glob.curpage) # takes a rtxPage object!
        return True
    elif pgnr[-1:].isnumeric() and rtxPage.exists(pgnr + "a"):
        glob.prevpage = glob.curpage
        glob.curpage = rtxPage(pgnr + "a")
        send_page(glob.curpage) # takes a rtxPage object!
        return True
    else:
        send_error(errormsg)
        return False

def send_error(msg):
    """ send an error message to the client """
    glob.ser.write(bytes(cept.error_prefix + msg + cept.error_suffix, "latin-1"))

def send_page(page):
    """ sends a page to the client """
    glob.ser.write(page.get_page())