from contextlib import contextmanager
from cStringIO import StringIO

import sqlalchemy


class Formatter(object):
    def __init__(self, out):
        self.level = 0
        self.out = out

    @contextmanager
    def indent(self, increase=1):
        self.level += increase
        yield
        self.level -= increase

    def write(self, string):
        self.out.write('  ' * self.level)
        self.out.write(string)
        self.out.write('\n')


def dump_schema(username, password, hostname, database, out):
    f = Formatter(out)
    url = sqlalchemy.engine.url.URL('mysql', username=username, password=password, host=hostname, database=database)
    engine = sqlalchemy.engine.create_engine(url)
    inspector = sqlalchemy.engine.reflection.Inspector.from_engine(engine)
    dump_database(inspector, f)


def dump_database(inspector, f):
    f.write(inspector.default_schema_name)
    with f.indent():
        # tables
        for table in sorted(inspector.get_table_names()):
            f.write('table: %s' % table)
            with f.indent():
                dump_table(inspector, table, f)
        # views
        for view in sorted(inspector.get_view_names()):
            f.write('view: %s' % view)
            with f.indent():
                dump_table(inspector, view, f)


def dump_table(inspector, table, f):
    # columns
    f.write('columns:')
    with f.indent():
        for column in sorted(inspector.get_columns(table)):
            f.write('- %s' % column.pop('name'))
            with f.indent():
                for k, v in column.iteritems():
                    f.write('%s: %s' % (k, v))
    # primary keys
    pks = inspector.get_primary_keys(table)
    if pks:
        f.write('primary keys:')
        with f.indent():
            for pk in pks:
                f.write('- %s' % pk)
    # foreign keys
    fks = inspector.get_foreign_keys(table)
    if fks:
        f.write('foreign keys:')
        with f.indent():
            for fk in fks:
                f.write('- %s' % fk.pop('name'))
                fk.pop('options')
                with f.indent():
                    for k, v in fk.iteritems():
                        if isinstance(v, list):
                            v = ', '.join(map(unicode, v))
                        f.write('%s: %s' % (k, v))
    # indexes
    indexes = inspector.get_indexes(table)
    if indexes:
        f.write('indexes:')
        with f.indent():
            for index in indexes:
                f.write('- %s' % index.pop('name'))
                with f.indent():
                    for k, v in index.iteritems():
                        if isinstance(v, list):
                            v = ', '.join(map(unicode, v))
                        f.write('%s: %s' % (k, v))
    # options
    options = inspector.get_table_options(table)
    if options:
        f.write('options:')
        with f.indent():
            for k, v in options.iteritems():
                if k.startswith('mysql_'):
                    k = k[6:]
                f.write('- %s: %s' % (k, v))


def main():
    import sys
    username, password, hostname, database = sys.argv[1:]
    dump_schema(username, password, hostname, database, sys.stdout)