from datetime import datetime, timedelta
import re

class Command:
    def __init__(self, cmdline, default_time = None):
        if default_time is None:
            self.time = datetime.now()
        else:
            self.time = default_time
        self.command = 'start'
        self.argstr = ''
        self.parseCommandLine(cmdline)

    def __str__(self):
        return "{'time' => '%s', 'command' => '%s', 'argstr' => '%s'}" % \
            (self.time, self.command, self.argstr)

    def parseCommandLine(self, cmdline):
        COMMANDS = {
                'out'       : 1,
                'report'    : 1,
                'status'    : 1,
                'fill'      : 1,
                'adjust'    : 1,
                'start'     : 1,
                'task'      : 1
                }
        ALIASES = {
                'rpt'       : 'report',
                'adj'       : 'adjust',
                'end'       : 'out',
                'st'        : 'status',
                'show'      : 'status',
                'f'         : 'fill'
                }
        args = []
        foundArgs = False

        while True:
            cmdline = cmdline.strip()
            if len(cmdline) < 1:
                break
            parts = cmdline.split(None, 1)
            token = parts[0]
            if not foundArgs:
                if self.parseDate(token):
                    pass
                elif self.parseTime(token):
                    pass
                elif token in COMMANDS:
                    self.command = token
                    foundArgs = True
                elif token in ALIASES:
                    self.command = ALIASES[token]
                    foundArgs = True
                else:
                    foundArgs = True
                    args.append(token)
            else:
                args.append(token)
            if len(parts) < 2:
                break
            cmdline = parts[1]

        self.argstr = ' '.join(args)

    def parseDate(self, dt):
        if dt.lower() == "yesterday":
            today = datetime.today()
            y = today - timedelta(days = 1)
            self.time = self.time.replace(
                    year = y.year, month = y.month, day = y.day)
            return True
        m = re.match('^(?:(\d{4})[-/])?(\d{1,2})[-/](\d{1,2})$', dt)
        if m is not None:
            # dt was a date string
            if m.group(1) is not None:
                self.time = self.time.replace(year = int(m.group(1)))
            month, day = int(m.group(2)), int(m.group(3))
            self.time = self.time.replace(month = month, day = day)
            return True
        return False

    def parseTime(self, timespec):
        m = re.match('^(\d{1,2}):?(\d{2})?(am?|pm?)?$', timespec, re.I)
        if m is not None:
            # an absolute time was given
            h = int(m.group(1))
            mins = 0 if m.group(2) is None else int(m.group(2))
            am_pm = '' if m.group(3) is None else m.group(3)[0].lower()
            if am_pm == 'p' and h < 12:
                h += 12
            elif am_pm == 'a' and h == 12:
                h = 0
            self.time = self.time.replace(hour = h, minute = mins, second = 0)
            return True
        m = re.match('^([-+])(\d+(?:\.\d+)?)([hms])?$', timespec, re.I)
        if m is not None:
            # a relative time was given
            plus_minus = m.group(1)
            hms = '' if m.group(3) is None else m.group(3)
            count = int(m.group(2))
            if hms == 'm':
                seconds = count * 60
            elif hms == 's':
                seconds = count
            else:                               # hours
                seconds = count * 60 * 60
            delta = timedelta(seconds = seconds)
            if plus_minus == '-':
                self.time -= delta
            else:
                self.time += delta
            return True
        return False