import md5, os, sets, shutil
import aes, regex
from point2 import Point

# undo/redo stack constants
ACT_NORM = 0
ACT_UNDO = 1
ACT_REDO = 2
STACK_LIMIT = 1024

# used for undo/redo stacks when text will need to be added back
class AddMove:
    def __init__(self, buffer, p, lines):
        self.buffer = buffer
        self.p = p
        self.lines = lines
    def restore(self, act=ACT_UNDO):
        assert act == ACT_UNDO or act == ACT_REDO
        self.buffer.insert_lines(self.p, self.lines, act)

# used for undo/redo stacks when text will need to be removed
class DelMove:
    def __init__(self, buffer, p1, p2):
        self.buffer = buffer
        self.p1 = p1
        self.p2 = p2
    def restore(self, act):
        assert act == ACT_UNDO or act == ACT_REDO
        self.buffer.delete(self.p1, self.p2, act)

# abstract class
class Buffer(object):
    def __init__(self, nl='\n', stack_limit=STACK_LIMIT):
        assert nl in ('\n', '\r', '\r\n'), "Invalid line ending"
        self.lines       = [""]
        self.windows     = []
        self.undo_stack  = []
        self.redo_stack  = []
        self.stack_limit = stack_limit
        self.nl          = nl
        self.modified    = False
        self.modes       = {}

    # basic file operation stuff
    def _open_file_r(self, path):
        path = os.path.realpath(path)
        if not os.path.isfile(path):
            raise Exception, "Path '%s' does not exist" % (path)
        if not os.access(path, os.R_OK):
            raise Exception, "Path '%s' cannot be read" % (path)
        f = open(path, 'r')
        return f
    def _open_file_w(self, path):
        if os.path.isfile(path):
            raise Exception, "Path '%s' already exists" % (path)
        d = os.path.dirname(path)
        if not os.access(d, os.R_OK):
            raise Exception, "Dir '%s' cannot be read" % (path)
        if not os.access(d, os.W_OK):
            raise Exception, "Dir '%s' cannot be written" % (path)
        f = open(path, 'w')
        return f
    def _temp_path(self, path):
        (dirname, basename) = os.path.split(path)
        return os.path.join(dirname, ".__%s__pmacs" % (basename))

    # undo/redo stack
    def _stack_trim(self, stack):
        if self.stack_limit:
            while len(stack) > self.stack_limit:
                stack.pop(0)
    def add_to_stack(self, move, act):
        if act == ACT_NORM:
            self.redo_stack = []
            self.undo_stack.append(move)
            self._stack_trim(self.undo_stack)
        elif act == ACT_UNDO:
            self.redo_stack.append(move)
            self._stack_trim(self.redo_stack)
        elif act == ACT_REDO:
            self.undo_stack.append(move)
            self._stack_trim(self.undo_stack)
        else:
            raise Exception, "Invalid act: %d" % (act)
    def undo(self):
        if len(self.undo_stack):
            move = self.undo_stack.pop(-1)
            move.restore(move, ACT_UNDO)
        else:
            raise Exception, "Nothing to Undo!"
    def redo(self):
        if len(self.redo_stack):
            move = self.redo_stack.pop(-1)
            move.restore(move, ACT_REDO)
        else:
            raise Exception, "Nothing to Redo!"

    # window-buffer communication
    def add_window(self, w):
        if w not in self.windows:
            self.windows.append(w)
    def remove_window(self, w):
        if w in self.windows:
            self.windows.remove(w)
    def _region_add(self, p1, p2, lines, act):
        move = DelMove(self, p1, p2)
        self.add_to_stack(move, act)
        for w in self.windows:
            w.region_added(p1, lines)
    def _region_del(self, p1, p2, lines, act):
        move = AddMove(self, p1, lines)
        self.add_to_stack(move, act)
        for w in self.windows:
            w.region_removed(p1, p2)

    # internal validation
    def _validate_point(self, p):
        self._validate_xy(p.x, p.y)
    def _validate_xy(self, x, y):
        assert y >= 0 and y < len(self.lines), \
            "xy1: %d >= 0 and %d < %d" % (y, y, len(self.lines))
        assert x >= 0 and x <= len(self.lines[y]), \
            "xy2: %d >= 0 and %d <= %d" % (x, x, len(self.lines[y]))
    def _validate_y(self, y):
        assert y >= 0 and y < len(self.lines), \
            "y: %d >= 0 and %d < %d" % (y, y, len(self.lines))

    # deal with the actual logical document string
    def num_chars(self):
        n = 0
        for line in self.lines[:-1]:
            n += len(line) + 1
        n += len(self.lines[-1])
        return n
    def num_lines(self):
        return len(self.lines)
    def make_string(self, nl='\n'):
        return nl.join(self.lines)

    # methods to be overridden by subclasses
    def name(self):
        return "Generic"
    def close(self):
        pass
    def open(self):
        pass
    def changed(self):
        return self.modified
    def reload(self):
        raise Exception, "%s reload: Unimplemented" % (self.name())
    def save_as(self, path, force=False):
        # check to see if the path exists, and if we're prepared to overwrite it
        # if yes to both, get its mode so we can preserve the path's permissions
        mode = None
        if os.path.exists(path):
            if force:
                mode = os.stat(self.path)[0]
            else:
                raise Exception, "oh no! %r already exists" % path

        # create the string that we're going to write into the file
        data = self.write_filter(self.make_string(nl=self.nl))

        # create a safe temporary path to write to, and write out data to it
        temp_path = self._temp_path()
        f2 = self._open_file_w(temp_path)
        f2.write(data)
        f2.close()

        # move the temporary file to the actual path; maybe change permissions
        shutil.move(temp_path, path)
        if mode:
            os.chmod(path, mode)

        # the file has not been modified now
        self.modified = False
    def readonly(self):
        return False
    def read_filter(self, data):
        return data
    def write_filter(self, data):
        return data

    # point retrieval
    def get_buffer_start(self):
        return Point(0, 0)
    def get_buffer_end(self):
        return Point(len(self.lines[-1]), len(self.lines) - 1)

    # data retrieval
    def get_sublines(self, p1, p2):
        self._validate_point(p1)
        self._validate_point(p2)
        assert p1 <= p2, "p1.x (%d) > p2.x (%d)" % (p1.x, p2.x)
        lines = []
        x = p1.x
        for i in range(p1.y, p2.y):
            lines.append(self.lines[i][x:])
            x = 0
        lines.append(self.lines[p2.y][x:p2.x])
        return lines
    def get_substring(self, p1, p2):
        lines = self.get_sublines(p1, p2)
        return '\n'.join(lines)

    # buffer set
    def set_lines(self, lines, force=False):
        if not force and self.readonly():
            raise Exception, "set_data: buffer is readonly"
        start = self.get_buffer_start()
        end   = self.get_buffer_end()
        self.delete(start, end, force=force)
        self.insert_lines(start, lines, force=force)
        self.modified = True
    def set_data(self, data, force=False):
        lines = data.split('\n')
        self.set_lines(lines, force)

    # insertion into buffer
    def insert_lines(self, p, lines, act=ACT_NORM, force=False):
        llen = len(lines)
        assert llen > 0
        if not force:
            assert not self.readonly(), "insert_string: buffer is read-only"
        p2 = p.vadd(len(lines[-1]), llen - 1)
        if llen > 1:
            self.lines.insert(p.y + 1, [])
            self.lines[p.y + 1] = lines[-1] + self.lines[p.y][p.x:]
            self.lines[p.y] = self.lines[p.y][:p.x] + lines[0]
            for i in range(1, llen - 1):
                self.lines.insert(p.y + i, lines[i])
        else:
            self.lines[p.y] = self.lines[p.y][:p.x] + lines[-1] + self.lines[p.y][p.x:]
        self._region_add(p, p2, lines, act)
        self.modified = True
    def insert_string(self, p, s, act=ACT_NORM, force=False):
        lines = s.split("\n")
        self.insert_lines(p, lines, act, force)
        
    # deletion from buffer
    def delete(self, p1, p2, act=ACT_NORM, force=False):
        """delete characters from p1 up to p2 from the buffer"""
        if not force:
            assert not self.readonly(), "delete_string: buffer is read-only"
        self._validate_point(p1)
        self._validate_point(p2)
        if p1 == p2:
            return
        assert p1 < p2, "p1 %r > p2 %r" % (p1, p2)
        lines = self.get_sublines(p1, p2)
        line1 = self.lines[p1.y]
        line2 = self.lines[p2.y]
        self.lines[p1.y:p2.y+1] = ["%s%s" % (line1[:p1.x], line2[p2.x:])]
        self._region_del(p1, p2, lines, act)
        self.modified = True
    def delete_char(self, p, act=ACT_NORM, force=False):
        if p.x == len(self.lines[p.y]):
            p2 = Point(0, p.y + 1)
        else:
            p2 = Point(p.x + 1, p.y)
        self.delete(p, p2, act, force)

    # random
    def count_leading_whitespace(self, y):
        line = self.lines[y]
        m = regex.leading_whitespace.match(line)
        if m:
            return m.end()
        else:
            # should not happen
            raise Exception, "iiiijjjj"

# scratch is a singleton
scratch = None
class ScratchBuffer(Buffer):
    def __new__(cls, *args, **kwargs):
        global scratch
        if scratch is None:
            scratch = object.__new__(ScratchBuffer, *args, **kwargs)
        return scratch
    def name(self):
        return "*Scratch*"
    def close(self):
        global scratch
        scratch = None

class DataBuffer(Buffer):
    def __init__(self, name, data, nl='\n'):
        Buffer.__init__(self, nl)
        self._name = name
        self.lines = data.split("\n")
    def name(self):
        return self._name
    def close(self):
        pass
    def readonly(self):
        return True

# console is another singleton
console = None
class ConsoleBuffer(Buffer):
    def __new__(cls, *args, **kwargs):
        global console
        if console is None:
            b = object.__new__(ConsoleBuffer, *args, **kwargs)
            console = b
        return console
    def __init__(self, nl='\n'):
        Buffer.__init__(self, nl)
        lines = ['Python Console\n',
                 "Evaluate python expressions in the editor's context (self)\n",
                 'Press Control-] to exit\n',
                 '\n']
        console.set_data(''.join(lines), force=True)
    def name(self):
        return '*Console*'
    def changed(self):
        return False
    def close(self):
        global console
        console = None
    def readonly(self):
        return True

class FileBuffer(Buffer):
    def __init__(self, path, nl='\n', name=None):
        '''fb = FileBuffer(path)'''
        Buffer.__init__(self, nl)
        self.path = os.path.realpath(path)
        self.checksum = None
        if name is None:
            self._name = os.path.basename(self.path)
        else:
            self._name = name
        if os.path.exists(self.path) and not os.access(self.path, os.W_OK):
            self._readonly = True
        else:
            self._readonly = False
    def readonly(self):
        return self._readonly

    def _open_file_r(self, path=None):
        if path is None:
            path = self.path
        path = os.path.realpath(path)
        self.path = path
        if not os.path.isfile(path):
            raise Exception, "Path '%s' does not exist" % (path)
        if not os.access(path, os.R_OK):
            raise Exception, "Path '%s' cannot be read" % (path)
        f = open(path, 'r')
        return f
    def _open_file_w(self, path=None):
        if path is None:
            path = self.path
        if os.path.isfile(path):
            raise Exception, "Path '%s' already exists" % (path)
        d = os.path.dirname(path)
        if not os.access(d, os.R_OK):
            raise Exception, "Dir '%s' cannot be read" % (path)
        if not os.access(d, os.W_OK):
            raise Exception, "Dir '%s' cannot be written" % (path)
        f = open(path, 'w')
        return f
    def _temp_path(self, path=None):
        if path is None:
            path = self.path
        (dirname, basename) = os.path.split(path)
        return os.path.join(dirname, ".__%s__pmacs" % (basename))

    # methods for dealing with the underlying resource, etc.
    def name(self):
        #return self.path
        return self._name
    def path_exists(self):
        return os.path.exists(self.path)
    def store_checksum(self, data):
        self.checksum = md5.new(data)
    def read(self):
        if self.path_exists():
            f = self._open_file_r()
            data = f.read()
            f.close()
            self.store_checksum(data)
        else:
            data = ''
        data = self.read_filter(data)
        #FIXME: this is horrible...but maybe not as horrible as using tabs??
        data = data.replace("\t", "    ")
        return data
    def open(self):
        data = self.read()
        self.lines = data.split(self.nl)
    def reload(self):
        self.open()
    def changed_on_disk(self):
        assert self.checksum is not None
        f = open(self.path)
        data = f.read()
        f.close()
        m = md5.new(data)
        return self.checksum.digest() != m.digest()
    def save(self, force=False):
        if self.readonly():
            raise Exception, "can't save a read-only file"

        if self.checksum is not None and force is False:
            # the file already existed and we took a checksum so make sure it's
            # still the same right now
            if not self.path_exists():
                raise Exception, "oh no! %r disappeared!" % self.path
            if self.changed_on_disk():
                raise Exception, "oh no! %r has changed on-disk!" % self.path

        temp_path = self._temp_path()
        data = self.make_string(nl=self.nl)
        data = self.write_filter(data)

        f2 = self._open_file_w(temp_path)
        f2.write(data)
        f2.close()

        if self.path_exists():
            mode = os.stat(self.path)[0]
            os.chmod(temp_path, mode)

        shutil.move(temp_path, self.path)
        self.store_checksum(data)
        self.modified = False
    def save_as(self, path):
        self.path = path
        self.save()

class AesBuffer(FileBuffer):
    def __init__(self, path, password, nl='\n'):
        '''fb = FileBuffer(path)'''
        FileBuffer.__init__(self, path, nl)
        self.password = password
    def read_filter(self, data):
        return aes.decrypt(data, self.password)
    def write_filter(self, data):
        return aes.encrypt(data, self.password)