"""Various helpers for string quoting/unquoting.
"""

import json
import re

try:
    from skytools._cquoting import (
        db_urldecode, db_urlencode, quote_bytea_raw,
        quote_copy, quote_literal, unescape, unquote_literal,
    )
except ImportError:
    from skytools._pyquoting import (
        db_urldecode, db_urlencode, quote_bytea_raw,
        quote_copy, quote_literal, unescape, unquote_literal,
    )

__all__ = (
    # _pyqoting / _cquoting
    "db_urldecode", "db_urlencode", "quote_bytea_raw",
    "quote_copy", "quote_literal", "unescape", "unquote_literal",
    # local
    "quote_bytea_literal", "quote_bytea_copy", "quote_statement",
    "quote_ident", "quote_fqident", "quote_json", "unescape_copy",
    "unquote_ident", "unquote_fqident",
    "json_encode", "json_decode",
    "make_pgarray",
)


#
# SQL quoting
#

def quote_bytea_literal(s):
    """Quote bytea for regular SQL."""

    return quote_literal(quote_bytea_raw(s))


def quote_bytea_copy(s):
    """Quote bytea for COPY."""

    return quote_copy(quote_bytea_raw(s))


def quote_statement(sql, dict_or_list):
    """Quote whole statement.

    Data values are taken from dict or list or tuple.
    """
    if hasattr(dict_or_list, 'items'):
        qdict = {}
        for k, v in dict_or_list.items():
            qdict[k] = quote_literal(v)
        return sql % qdict
    else:
        qvals = [quote_literal(v) for v in dict_or_list]
        return sql % tuple(qvals)


# reserved keywords (RESERVED_KEYWORD + TYPE_FUNC_NAME_KEYWORD)
_ident_kwmap = {
    "all": 1, "analyse": 1, "analyze": 1, "and": 1, "any": 1, "array": 1, "as": 1,
    "asc": 1, "asymmetric": 1, "authorization": 1, "between": 1, "binary": 1, "both": 1, "case": 1,
    "cast": 1, "check": 1, "collate": 1, "collation": 1, "column": 1, "concurrently": 1,
    "constraint": 1, "create": 1, "cross": 1, "current_catalog": 1, "current_date": 1,
    "current_role": 1, "current_schema": 1, "current_time": 1, "current_timestamp": 1,
    "current_user": 1, "default": 1, "deferrable": 1, "desc": 1, "distinct": 1,
    "do": 1, "else": 1, "end": 1, "errors": 1, "except": 1, "false": 1, "fetch": 1,
    "for": 1, "foreign": 1, "freeze": 1, "from": 1, "full": 1, "grant": 1, "group": 1,
    "having": 1, "ilike": 1, "in": 1, "initially": 1, "inner": 1, "intersect": 1,
    "into": 1, "is": 1, "isnull": 1, "join": 1, "lateral": 1, "leading": 1, "left": 1,
    "like": 1, "limit": 1, "localtime": 1, "localtimestamp": 1, "natural": 1, "new": 1,
    "not": 1, "notnull": 1, "null": 1, "off": 1, "offset": 1, "old": 1, "on": 1, "only": 1,
    "or": 1, "order": 1, "outer": 1, "over": 1, "overlaps": 1, "placing": 1, "primary": 1,
    "references": 1, "returning": 1, "right": 1, "select": 1, "session_user": 1,
    "similar": 1, "some": 1, "symmetric": 1, "table": 1, "tablesample": 1, "then": 1, "to": 1, "trailing": 1,
    "true": 1, "union": 1, "unique": 1, "user": 1, "using": 1, "variadic": 1, "verbose": 1,
    "when": 1, "where": 1, "window": 1, "with": 1,
}

_ident_bad = re.compile(r"[^a-z0-9_]|^[0-9]")


def quote_ident(s):
    """Quote SQL identifier.

    If is checked against weird symbols and keywords.
    """

    if _ident_bad.search(s) or s in _ident_kwmap:
        s = '"%s"' % s.replace('"', '""')
    elif not s:
        return '""'
    return s


def quote_fqident(s):
    """Quote fully qualified SQL identifier.

    The '.' is taken as namespace separator and
    all parts are quoted separately
    """
    tmp = s.split('.', 1)
    if len(tmp) == 1:
        return 'public.' + quote_ident(s)
    return '.'.join([quote_ident(name) for name in tmp])


#
# quoting for JSON strings
#

_jsre = re.compile(r'[\x00-\x1F\\/"]')
_jsmap = {
    "\b": "\\b", "\f": "\\f", "\n": "\\n", "\r": "\\r",
    "\t": "\\t", "\\": "\\\\", '"': '\\"',
    "/": "\\/",   # to avoid html attacks
}


def _json_quote_char(m):
    """Quote single char."""
    c = m.group(0)
    try:
        return _jsmap[c]
    except KeyError:
        return r"\u%04x" % ord(c)


def quote_json(s):
    """JSON style quoting."""
    if s is None:
        return "null"
    return '"%s"' % _jsre.sub(_json_quote_char, s)


def unescape_copy(val):
    r"""Removes C-style escapes, also converts "\N" to None.
    """
    if val == r"\N":
        return None
    return unescape(val)


def unquote_ident(val):
    """Unquotes possibly quoted SQL identifier.
    """
    if len(val) > 1 and val[0] == '"' and val[-1] == '"':
        return val[1:-1].replace('""', '"')
    if val.find('"') > 0:
        raise Exception('unsupported syntax')
    return val.lower()


def unquote_fqident(val):
    """Unquotes fully-qualified possibly quoted SQL identifier.
    """
    tmp = val.split('.', 1)
    return '.'.join([unquote_ident(i) for i in tmp])


def json_encode(val=None, **kwargs):
    """Creates JSON string from Python object.
    """
    return json.dumps(val or kwargs)


def json_decode(s):
    """Parses JSON string into Python object.
    """
    return json.loads(s)


#
# Create Postgres array
#

# any chars not in "good" set?  main bad ones: [ ,{}\"]
_pgarray_bad_rx = r"[^0-9a-z_.%&=()<>*/+-]"
_pgarray_bad_rc = None


def _quote_pgarray_elem(s):
    if s is None:
        return 'NULL'
    s = str(s)
    if _pgarray_bad_rc.search(s):
        s = s.replace('\\', '\\\\')
        return '"' + s.replace('"', r'\"') + '"'
    elif not s:
        return '""'
    return s


def make_pgarray(lst):
    r"""Formats Python list as Postgres array.
    Reverse of parse_pgarray().
    """

    global _pgarray_bad_rc
    if _pgarray_bad_rc is None:
        _pgarray_bad_rc = re.compile(_pgarray_bad_rx)

    items = [_quote_pgarray_elem(v) for v in lst]
    return '{' + ','.join(items) + '}'