#!/usr/bin/env python3

import json,lzma,os,subprocess,sys,time
from zopen import zopen
import botocore.session # if you have installed boto3 properly then you already have botocore

#-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------

main_region = 'us-east-1'
compact     = (',',':')
ls          = ['ls','-dGl','--full-time']
r           = 'region'
base_dir    = 'attic' # relative to home directory
ami_json    = 'amijson'

#-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------
# these functions make code look less cluttered where isinstance() is needed.
#-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------
from decimal import Decimal
from io import IOBase

def is_bb        (x):return isinstance(x, (bytes,bytearray) )
def is_bi        (x):return isinstance(x, (bool,int) )
def is_bif       (x):return isinstance(x, (bool,int,float) )
def is_bifc      (x):return isinstance(x, (bool,int,float,complex) )
def is_bifcd     (x):return isinstance(x, (bool,int,float,complex,Decimal) )
def is_bool      (x):return isinstance(x, bool )
def is_bytearray (x):return isinstance(x, bytearray )
def is_bytes     (x):return isinstance(x, bytes )
def is_complex   (x):return isinstance(x, complex)
def is_decimal   (x):return isinstance(x, Decimal )
def is_dict      (x):return isinstance(x, dict )
def is_ds        (x):return isinstance(x, (dict,set) )
def is_fc        (x):return isinstance(x, (float,complex) )
def is_fcd       (x):return isinstance(x, (float,complex,Decimal) )
def is_fd        (x):return isinstance(x, (float,Decimal) )
def is_float     (x):return isinstance(x, float )
def is_frozenset (x):return isinstance(x, frozenset )
def is_if        (x):return isinstance(x, (int,float) )
def is_ifc       (x):return isinstance(x, (int,float,complex) )
def is_ifcd      (x):return isinstance(x, (int,float,complex,Decimal) )
def is_ifd       (x):return isinstance(x, (int,float,Decimal) )
def is_int       (x):return isinstance(x, int )
def is_iobase    (x):return isinstance(x, IOBase )
def is_lio       (x):return isinstance(x, (list,IOBase) )
def is_list      (x):return isinstance(x, list )
def is_ls        (x):return isinstance(x, (list,set) )
def is_lt        (x):return isinstance(x, (list,tuple) )
def is_ltsf      (x):return isinstance(x, (list,tuple,set,frozenset) )
def is_ltsfd     (x):return isinstance(x, (list,tuple,set,frozenset,dict) )
def is_sbb       (x):return isinstance(x, (str,bytes,bytearray) )
def is_set       (x):return isinstance(x, set )
def is_sf        (x):return isinstance(x, (set,frozenset) )
def is_si        (x):return isinstance(x, (str,int) )
def is_str       (x):return isinstance(x, str )
def is_tf        (x):return isinstance(x, (tuple,frozenset) )
def is_tuple     (x):return isinstance(x, tuple )
#-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------

#-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------
home_dir = os.path.expanduser('~')

try:
    os.chdir(home_dir)
except OSError:
    exit('unable to change to home directory {home_dir!r}')

try:
    os.chdir(base_dir)
except OSError:
    exit('unable to change to base directory {base_dir!r}')

#-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------
# create a list of possible names to guess the name of the user preferred regions file
#-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------
fns = []
for a in ('-','_','.',''):
    for b in ('',f'my{a}'):
        for c in ('',f'pre{a}',f'pref{a}',f'prefer{a}',f'preferred{a}'):
            for d in ('',f'aws{a}'):
                for e in ('region','regions'):
                    for f in ('','.txt','.reg','.regs','.list'):
                        for g in ('','.gz','.bz2','.xz'):
                            fns.append(b+c+d+e+f+g)

#-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------
cwd = os.getcwd()
exe = sys.argv.pop(0)
ses = botocore.session.get_session()
w,h = os.get_terminal_size()
errors = 0

def eprint(*args,**kwargs):
    kwargs['file'] = sys.stderr
    kwargs['flush'] = True
    result = False
    try:
        result = print(*args,**kwargs)
    except BrokenPipeError:
        pass
    return result

def get_aws_regions_list(region=None):
    if region is None:
        region = main_region
    session = ses
    if not session:
        session = botocore.session.get_session()
    client = session.create_client('ec2', region_name=region)
    response = client.describe_regions()
    if 'Regions' in response:
        r = response['Regions']
        if all('RegionName' in x for x in r):
            regions = [x['RegionName'] for x in r]
            return regions
        raise TypeError('AWS sent a bad region object: one or more regions had no name.')
    raise TypeError('AWS sent a bad response: no region object.')

def by_creation_date(a):
    """Key function for sorting AMI items by creation date."""
    return a.get('CreationDate','0')

eprint('searching for a local file holding the user preferred list of regions')
eprint(f'there are {len(fns)} such file names to try:')
all_regions = []
line_end = '\n'
pos = 0
num = 0
for fn in fns:
    if not fn:
        continue
    afn = os.path.join(home_dir,fn)
    new = len(fn)
    if pos+1+new > w:
        # print this name on the next line
        print('\n'+fn,end='',flush=True)
        pos = new
        num = 1
    else:
        # print this name on the same line
        if pos:
            print('',fn,end='',flush=True)
        else:
            print(fn,end='',flush=True)
        pos += 1+new
        num += 1
    if os.path.lexists(afn):
        with zopen(afn) as f:
#-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------
# 4 different ways to do this
# the first 2 fail improperly due to iterator expecting to get bytes type from text file
#-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------
#            all_regions = [x.strip()for x in f]
#-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------
#            all_regions = []
#            for x in f:
#                all_regions.append(x.strip())
#-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------
            all_regions = f.read().splitlines()
#-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------
#            all_regions = []
#            for x in f.readlines():
#                all_regions.append(x.strip())
#-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------.-------
        n = len(all_regions)
        if not n: # ignore empty lists as if the do not exist
            continue
        print(f'\n\nfound one at {fn!r} with {n} regions listed in it.\n',flush=True)
        break
else:
    eprint('\n\n>>> no file with a list of regions was found\n>>> getting a list from AWS region',main_region,flush=True)
    x2 = time.time()
    all_regions = get_aws_regions_list(main_region)
    x3 = time.time()
    eprint('duration =',x3-x2)
    n = len(all_regions)
    eprint(n,'regions')

if not all_regions:
    exit('\nunable to get a list of preferred or official regions,\nnot even from AWS ... giving up\n')

# determine what the directory name is for today
if 'ami_json_ymd' not in locals():
    ami_json_ymd = None

if not is_str(ami_json_ymd):
    ami_json_ymd = ami_json + '-%Y-%m-%d.d'

if '%' in ami_json_ymd:
    ami_json_ymd = time.strftime(ami_json_ymd,time.localtime(time.time()))

if os.path.lexists(ami_json_ymd):
    exit(f'directory {ami_json_ymd!r} already exists - remove it or rename it and try again')

print(f'CREATING DIRECTORY {ami_json_ymd!r}',flush=1)
try:
    os.makedirs(ami_json_ymd)
except OSError:
    exit('unknown error creating directory {ami_json_ymd!r}')

try:
    os.chdir(ami_json_ymd)
except FileNotFoundError:
    exit('directory {ami_json_ymd!r} was not created')
except OSError:
    exit('cannot change currect working directory to {ami_json_ymd!r}')

# the command line may have a list of regions
use_regions = []
for arg in sys.argv:
    if arg in all_regions:
        use_regions.append(arg)
    else:
        eprint(f'Invalid region name {arg!r}')
        errors += 1

if errors:
    exit(f'aborting due to {errors} error{"s"[errors==1:]}')

if not use_regions: # if no regions specified
    use_regions[:] = all_regions # then do all regions
print('all_regions =',repr(all_regions),flush=1)

n = len(all_regions)
eprint(f'now fetching AMI data from {n} regions')

c = 0
print('use_regions =',repr(use_regions),flush=1)
for region in sorted(use_regions):
    c += 1
    eprint(f'region {c}/{n} is {region!r}')
    print('region =',repr(region),flush=1)

    x0 = time.time()
    result = ses.create_client('ec2',region_name=region).describe_images(DryRun=False)
    x1 = time.time()

    eprint('duration =',x1-x0)
    if not result or 'Images' not in result:
        eprint('request "describe_images" failed for region',region)
        continue

    images = result['Images']

    amis = []
    for image in images:
        if image.get('ImageType',None)=='machine':
            amis.append(image)
    amis.sort(key=by_creation_date)

    # dump data for this region as compressed JSON
    fn = f'aws-amis-{region}.json.xz'
    eprint(f'in {os.getcwd()!r} dumping data to {fn!r}',flush=True)
    x4 = time.time()
    fz = lzma.open(fn,'wt',preset=9)
    json.dump(amis,fz,sort_keys=True,separators=compact,indent=4)
    fz.close()
    x5 = time.time()
    eprint('duration =',x5-x4)
    subprocess.call(ls+[fn]) # let "ls" show the file

tn = ami_json + '.' + str(int(time.time()*3906250))
os.chdir(home_dir)
os.chdir(base_dir)
os.symlink(ami_json_ymd,tn)
os.rename(tn,ami_json)