# -*- coding: utf-8 -*-

""" PostgreSQL client """

import datetime
import logging
import sys

import psycopg2

log = logging.getLogger(__name__)


#
# Exceptions
#

class PgDBException(Exception):
    """ That is the base exception class for all the other exceptions provided by this module. """

    def __init__(self, error, *args, **kwargs):
        for arg, value in kwargs.items():
            setattr(self, arg, value)
        super().__init__(error.format(*args, **kwargs))


class PgDBDuplicatedSQLParameter(PgDBException, KeyError):
    """
    Raised when trying to set a SQL query parameter
    and an other parameter with the same name is already set
    """

    def __init__(self, parameter_name):
        super().__init__(
            "Duplicated SQL parameter '{parameter_name}'",
            parameter_name=parameter_name
        )


class PgDBUnsupportedWHEREClauses(PgDBException, TypeError):
    """
    Raised when trying to execute query with unsupported
    WHERE clauses provided
    """

    def __init__(self, where_clauses):
        super().__init__(
            "Unsupported WHERE clauses: {where_clauses}",
            where_clauses=where_clauses
        )


class PgDB:
    """ PostgreSQL client """

    host = ""
    user = ""
    pwd = ""
    db = ""

    con = 0

    date_format = '%Y-%m-%d'
    datetime_format = '%Y-%m-%d %H:%M:%S'

    def __init__(self, host, user, pwd, db, just_try=False):
        self.host = host
        self.user = user
        self.pwd = pwd
        self.db = db
        self.just_try = just_try

    def connect(self):
        """ Connect to PostgreSQL server """
        if self.con == 0:
            try:
                con = psycopg2.connect(
                    dbname=self.db,
                    user=self.user,
                    host=self.host,
                    password=self.pwd
                )
                self.con = con
            except Exception:
                logging.fatal(
                    'An error occured during Postgresql database connection (%s@%s, database=%s).',
                    self.user, self.host, self.db, exc_info=1
                )
                sys.exit(1)
        return True

    def close(self):
        """ Close connection with PostgreSQL server (if opened) """
        if self.con:
            self.con.close()

    def setEncoding(self, enc):
        """ Set connection encoding """
        if self.con:
            try:
                self.con.set_client_encoding(enc)
                return True
            except Exception:
                log.error(
                    'An error occured setting Postgresql database connection encoding to "%s"',
                    enc, exc_info=1
                )
        return False

    def doSQL(self, sql, params=None):
        """
        Run SQL query and commit changes (rollback on error)

        :param sql: The SQL query
        :param params: The SQL query's parameters as dict (optional)

        :return: True on success, False otherwise
        :rtype: bool
        """
        if self.just_try:
            log.debug("Just-try mode : do not really execute SQL query '%s'", sql)
            return True

        cursor = self.con.cursor()
        try:
            if params is None:
                cursor.execute(sql)
            else:
                cursor.execute(sql, params)
            self.con.commit()
            return True
        except Exception:
            log.error(
                'Error during SQL request "%s" %s',
                sql,
                "with params = %s" % ', '.join([
                    "%s = %s" % (key, value)
                    for key, value in params.items()
                ]) if params else "without params",
                exc_info=True
            )
            self.con.rollback()
            return False

    def doSelect(self, sql, params=None):
        """
        Run SELECT SQL query and return list of selected rows as dict

        :param sql: The SQL query
        :param params: The SQL query's parameters as dict (optional)

        :return: List of selected rows as dict on success, False otherwise
        :rtype: list, bool
        """
        cursor = self.con.cursor()
        try:
            cursor.execute(sql, params)
            results = cursor.fetchall()
            return results
        except Exception:
            log.error(
                'Error during SQL request "%s" %s',
                sql,
                "with params = %s" % ', '.join([
                    "%s = %s" % (key, value)
                    for key, value in params.items()
                ]) if params else "without params",
                exc_info=True
            )
        return False


    #
    # SQL helpers
    #

    @classmethod
    def _combine_params(cls, params, to_add=None, **kwargs):
        if to_add:
            assert isinstance(to_add, dict), "to_add must be a dict or None"
            params = cls._combine_params(params, **to_add)

        for param, value in kwargs.items():
            if param in params:
                raise PgDBDuplicatedSQLParameter(param)
            params[param] = value
        return params

    @classmethod
    def _format_where_clauses(cls, where_clauses, params=None, where_op=None):
        """
        Format WHERE clauses

        :param where_clauses: The WHERE clauses. Could be:
            - a raw SQL WHERE clause as string
            - a tuple of two elements: a raw WHERE clause and its parameters as dict
            - a dict of WHERE clauses with field name as key and WHERE clause value as value
            - a list of any of previous valid WHERE clauses
        :param params: Dict of other already set SQL query parameters (optional)
        :param where_op: SQL operator used to combine WHERE clauses together (optional, default: AND)

        :return: A tuple of two elements: raw SQL WHERE combined clauses and parameters on success
        :rtype: string, bool
        """
        if params is None:
            params = dict()
        if where_op is None:
            where_op = 'AND'

        if isinstance(where_clauses, str):
            return (where_clauses, params)

        if isinstance(where_clauses, tuple) and len(where_clauses) == 2 and isinstance(where_clauses[1], dict):
            cls._combine_params(params, where_clauses[1])
            return (where_clauses[0], params)

        if isinstance(where_clauses, (list, tuple)):
            sql_where_clauses = []
            for where_clause in where_clauses:
                sql2, params = cls._format_where_clauses(where_clause, params=params, where_op=where_op)
                sql_where_clauses.append(sql2)
            return (
                (" %s " % where_op).join(sql_where_clauses),
                params
            )

        if isinstance(where_clauses, dict):
            sql_where_clauses = []
            for field, value in where_clauses.items():
                param = field
                if field in params:
                    idx = 1
                    while param in params:
                        param = '%s_%d' % (field, idx)
                        idx += 1
                cls._combine_params(params, {param: value})
                sql_where_clauses.append(
                    '"{field}" = %({param})s'.format(field=field, param=param)
                )
            return (
                (" %s " % where_op).join(sql_where_clauses),
                params
            )
        raise PgDBUnsupportedWHEREClauses(where_clauses)

    @classmethod
    def _add_where_clauses(cls, sql, params, where_clauses, where_op=None):
        """
        Add WHERE clauses to an SQL query

        :param sql: The SQL query to complete
        :param params: The dict of parameters of the SQL query to complete
        :param where_clauses: The WHERE clause (see _format_where_clauses())
        :param where_op: SQL operator used to combine WHERE clauses together (optional, default: see _format_where_clauses())

        :return:
        :rtype: A tuple of two elements: raw SQL WHERE combined clauses and parameters
        """
        if where_clauses:
            sql_where, params = cls._format_where_clauses(where_clauses, params=params, where_op=where_op)
            sql += " WHERE " + sql_where
        return (sql, params)


    def insert(self, table, values, just_try=False):
        """ Run INSERT SQL query """
        sql = 'INSERT INTO "%s" ("%s") VALUES (%s)' % (
            table,
            '", "'.join(values.keys()),
            ", ".join([
                '%({0})s'.format(key)
                for key in values
            ])
        )

        if just_try:
            log.debug("Just-try mode : execute INSERT query : %s", sql)
            return True

        log.debug(sql)
        if not self.doSQL(sql, params=values):
            log.error("Fail to execute INSERT query (SQL : %s)", sql)
            return False
        return True

    def update(self, table, values, where_clauses, where_op=None, just_try=False):
        """ Run UPDATE SQL query """
        sql = 'UPDATE "%s" SET %s' % (
            table,
            ", ".join([
                '"{0}" = %({0})s'.format(key)
                for key in values
            ])
        )
        params = values

        try:
            sql, params = self._add_where_clauses(sql, params, where_clauses, where_op=where_op)
        except (PgDBDuplicatedSQLParameter, PgDBUnsupportedWHEREClauses):
            log.error('Fail to add WHERE clauses', exc_info=True)
            return False

        if just_try:
            log.debug("Just-try mode : execute UPDATE query : %s", sql)
            return True

        log.debug(sql)
        if not self.doSQL(sql, params=params):
            log.error("Fail to execute UPDATE query (SQL : %s)", sql)
            return False
        return True

    def delete(self, table, where_clauses, where_op='AND', just_try=False):
        """ Run DELETE SQL query """
        sql = 'DELETE FROM "%s"' % table
        params = dict()

        try:
            sql, params = self._add_where_clauses(sql, params, where_clauses, where_op=where_op)
        except (PgDBDuplicatedSQLParameter, PgDBUnsupportedWHEREClauses):
            log.error('Fail to add WHERE clauses', exc_info=True)
            return False

        if just_try:
            log.debug("Just-try mode : execute UPDATE query : %s", sql)
            return True

        log.debug(sql)
        if not self.doSQL(sql, params=params):
            log.error("Fail to execute UPDATE query (SQL : %s)", sql)
            return False
        return True

    def truncate(self, table, just_try=False):
        """ Run TRUNCATE SQL query """

        sql = 'TRUNCATE "%s"' % table

        if just_try:
            log.debug("Just-try mode : execute TRUNCATE query : %s", sql)
            return True

        log.debug(sql)
        if not self.doSQL(sql):
            log.error("Fail to execute TRUNCATE query (SQL : %s)", sql)
            return False
        return True

    def select(self, table, where_clauses=None, fields=None, where_op='AND', order_by=None, just_try=False):
        """ Run SELECT SQL query """
        sql = "SELECT "
        if fields is None:
            sql += "*"
        elif isinstance(fields, str):
            sql += '"%s"' % fields
        else:
            sql += '"' + '", "'.join(fields) + '"'

        sql += ' FROM "%s"' % table
        params = dict()

        try:
            sql, params = self._add_where_clauses(sql, params, where_clauses, where_op=where_op)
        except (PgDBDuplicatedSQLParameter, PgDBUnsupportedWHEREClauses):
            log.error('Fail to add WHERE clauses', exc_info=True)
            return False

        if order_by:
            sql += ' ORDER BY %s' % order_by

        if just_try:
            log.debug("Just-try mode : execute SELECT query : %s", sql)
            return just_try

        return self.doSelect(sql, params=params)


    #
    # Depreated helpers
    #

    @classmethod
    def _quote_value(cls, value):
        """ Quote a value for SQL query """
        if value is None:
            return 'NULL'

        if isinstance(value, (int, float)):
            return str(value)

        if isinstance(value, datetime.datetime):
            value = cls._format_datetime(value)
        elif isinstance(value, datetime.date):
            value = cls._format_date(value)

        return "'%s'" % value.replace("'", "''")

    @classmethod
    def _format_datetime(cls, value):
        """ Format datetime object as string """
        assert isinstance(value, datetime.datetime)
        return value.strftime(cls.datetime_format)

    @classmethod
    def _format_date(cls, value):
        """ Format date object as string """
        assert isinstance(value, (datetime.date, datetime.datetime))
        return value.strftime(cls.date_format)

    @classmethod
    def time2datetime(cls, time):
        """ Convert timestamp to datetime string """
        return cls._format_datetime(datetime.datetime.fromtimestamp(int(time)))

    @classmethod
    def time2date(cls, time):
        """ Convert timestamp to date string """
        return cls._format_date(datetime.date.fromtimestamp(int(time)))