import math
import random
from textwrap import dedent



class MySQLOptimizer:
    defaults = {
        'mysql_dir': "/var/lib/mysql",

        'log_error': "/var/lib/mysql/mysqld.log",
        'slow_query_log_file': "/var/lib/mysql/mysqld-slow.log",

        'pid_file': "/var/lib/mysql/mysqld.pid",

        'mysql_ram_gb': 1,

        'query_cache_type': 0,
        'query_cache_size': 0,

        'long_query_time': 2,
        'max_connections': 500,

        'server_id': random.randint(100000, 999999)
    }


    @staticmethod
    def mycnf_innodb_log_file_size_MB(innodb_buffer_pool_size_GB):
        if innodb_buffer_pool_size_GB > 64:
            return '768M'
        if innodb_buffer_pool_size_GB > 24:
            return '512M'
        if innodb_buffer_pool_size_GB > 8:
            return '256M'
        if innodb_buffer_pool_size_GB > 2:
            return '128M'

        return '64M'

    @staticmethod
    def output_memory_gb(gb):

        if math.fabs(math.ceil(gb) - gb) < 0.01:
            return str(int(gb)) + 'G'

        return str(int(gb * 1024)) + 'M'

    @staticmethod
    def mycnf_make(m):
        m['innodb_buffer_pool_size'] = MySQLOptimizer.output_memory_gb(float(m['mysql_ram_gb']) * 0.15)
        m['innodb_log_file_size'] = MySQLOptimizer.mycnf_innodb_log_file_size_MB(m['mysql_ram_gb'])
        return m

    @staticmethod
    def output_my_cnf(_metaconf):
        return dedent("""
[mysqld]

# GENERAL #
user                           = mysql
default-storage-engine         = InnoDB
#socket                         = {mysql_dir}/mysql.sock
#pid-file                       = {pid_file}

# MyISAM #
# key-buffer-size                = 32M
# myisam-recover                 = FORCE,BACKUP

# SAFETY #
max-allowed-packet             = 16M
max-connect-errors             = 1000000
sql-mode                       = NO_ENGINE_SUBSTITUTION,NO_AUTO_CREATE_USER
sysdate-is-now                 = 1
innodb-strict-mode             = 1

# DATA STORAGE #
datadir                        = {mysql_dir}

# SERVER ID # 
server-id                      = {server_id}

# CACHES AND LIMITS #
max-connections                = {max_connections}
tmp-table-size                 = 32M
max-heap-table-size            = 32M
query-cache-type               = {query_cache_type}
query-cache-size               = {query_cache_size}
thread-cache-size              = 50
open-files-limit               = 65535
table-definition-cache         = 1024
table-open-cache               = 2048

# INNODB #
innodb-flush-method            = O_DIRECT
innodb-log-files-in-group      = 2
innodb-log-file-size           = {innodb_log_file_size}
innodb-flush-log-at-trx-commit = 1
innodb-file-per-table          = 1
innodb-buffer-pool-size        = {innodb_buffer_pool_size}

# LOGGING #
#log-error                      = {log_error}
slow-query-log                 = 1
#slow-query-log-file            = {slow_query_log_file}
log-queries-not-using-indexes  = OFF
long_query_time                = 30

[mysqldump]
max-allowed-packet             = 16M

!includedir /etc/mysql/conf.d/
!includedir /etc/mysql/mariadb.conf.d/

""".format(**MySQLOptimizer.mycnf_make(_metaconf)))

    @staticmethod
    def generateRecommendations(detectedRam):
        MySQLOptimizer.defaults['mysql_ram_gb'] = int(float(detectedRam))
        return MySQLOptimizer.output_my_cnf(MySQLOptimizer.defaults)