import vim
import re
from vim_bridge import bridged


def get_table_bounds():
    row, col = vim.current.window.cursor
    upper = lower = row
    try:
        while vim.current.buffer[upper - 1].strip():
            upper -= 1
    except IndexError:
        pass
    else:
        upper += 1

    try:
        while vim.current.buffer[lower - 1].strip():
            lower += 1
    except IndexError:
        pass
    else:
        lower -= 1

    return (upper, lower)

def join_rows(rows, sep='\n'):
    """Given a list of rows (a list of lists) this function returns a
    flattened list where each the individual columns of all rows are joined
    together using the line separator.

    """
    output = []
    for row in rows:
        # grow output array, if necessary
        if len(output) <= len(row):
            for i in range(len(row) - len(output)):
                output.extend([[]])

        for i, field in enumerate(row):
            field_text = field.strip()
            if field_text:
                output[i].append(field_text)
    return map(lambda lines: sep.join(lines), output)


def unify_table(table):
    """Given a list of rows (i.e. a table), this function returns a new table
    in which all rows have an equal amount of columns.  If all full column is
    empty (i.e. all rows have that field empty), the column is removed.

    """
    max_fields = max(map(lambda row: len(row), table))
    empty_cols = [True] * max_fields
    output = []
    for row in table:
        curr_len = len(row)
        if curr_len < max_fields:
            row += [''] * (max_fields - curr_len)
        output.append(row)

        # register empty columns (to be removed at the end)
        for i in range(len(row)):
            if row[i].strip():
                empty_cols[i] = False

    # remove empty columns from all rows
    table = output
    output = []
    for row in table:
        cols = []
        for i in range(len(row)):
            should_remove = empty_cols[i]
            if not should_remove:
                cols.append(row[i])
        output.append(cols)

    return output


def split_table_row(row_string):
    if row_string.find("|") >= 0:
        # first, strip off the outer table drawings
        row_string = re.sub(r'^\s*\||\|\s*$', '', row_string)
        return re.split(r'\s*\|\s*', row_string.strip())
    return re.split(r'\s\s+', row_string.rstrip())


def parse_table(raw_lines):
    select_data_lines = lambda line: not re.match('^[\t +=-]+$', line)
    lines = filter(select_data_lines, raw_lines)
    lines = map(split_table_row, lines)
    return unify_table(lines)


def table_line(widths, header=False):
    if header:
        linechar = '='
    else:
        linechar = '-'
    sep = '+'
    parts = []
    for width in widths:
        parts.append(linechar * width)
    if parts:
        parts = [''] + parts + ['']
    return sep.join(parts)


def get_column_widths(table):
    widths = []
    for row in table:
        num_fields = len(row)
        # dynamically grow
        if num_fields >= len(widths):
            widths.extend([0] * (num_fields - len(widths)))
        for i in range(num_fields):
            field_text = row[i]
            field_width = len(field_text)
            widths[i] = max(widths[i], field_width)
    return widths


def pad_fields(table, widths=None):
    """Pads fields of the table, so each row lines up nicely with the others.
    If the widths param is None, the widths are calculated automatically.

    """
    if widths is None:
        widths = get_column_widths(table)
    widths = map(lambda w: ' %-' + str(w) + 's ', widths)

    # Pad all fields using the calculated widths
    output = []
    for row in table:
        new_row = []
        for i in range(len(row)):
            col = row[i]
            col = widths[i] % col.strip()
            new_row.append(col)
        output.append(new_row)
    return output


def draw_table(table):
    if table == []:
        return []

    col_widths = get_column_widths(table)
    table = pad_fields(table, col_widths)

    # Reserve room for the spaces
    col_widths = map(lambda x: x + 2, col_widths)
    header_line = table_line(col_widths, header=True)
    normal_line = table_line(col_widths, header=False)

    output = [header_line]
    first = True
    for row in table:
        output.append("|".join([''] + row + ['']))
        if first:
            output.append(header_line)
            first = False
        else:
            output.append(normal_line)

    return output


@bridged
def reformat_table():
    upper, lower = get_table_bounds()
    slice = vim.current.buffer[upper - 1:lower]
    table = parse_table(slice)
    slice = draw_table(table)
    vim.current.buffer[upper - 1:lower] = slice