"""
 Licensed to the Apache Software Foundation (ASF) under one or more
 contributor license agreements.  See the NOTICE file distributed with
 this work for additional information regarding copyright ownership.
 The ASF licenses this file to You under the Apache License, Version 2.0
 (the "License"); you may not use this file except in compliance with
 the License.  You may obtain a copy of the License at

     http://www.apache.org/licenses/LICENSE-2.0

 Unless required by applicable law or agreed to in writing, software
 distributed under the License is distributed on an "AS IS" BASIS,
 WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 See the License for the specific language governing permissions and
 limitations under the License.
"""

import functools
import json
import marshal
import base64
import types
import os
import inspect
import composer
import re
import requests
import traceback
from conductor import __version__

def escape(str):
    return re.sub(r'(\n|\t|\r|\f|\v|\\|\')', lambda m:{'\n':'\\n','\t':'\\t','\r':'\\r','^\f':'\\f','\v':'\\v','\\':'\\\\','\'':'\\\''}[m.group()], str)

def synthesize(composition): # dict
    code = '# generated by composer v'+composition['version']+' and conductor v'+__version__+'\n\nimport os\nimport functools\nimport json\nimport inspect\nimport re\nimport base64\nimport marshal\nimport types\nimport requests\nimport urllib.parse'
    code += '\n\n' + inspect.getsource(composer.ComposerError)
    code += '\ncomposition=json.loads(\''+escape(json.dumps(composition['composition'], default=composer.serialize, ensure_ascii=True))+'\')'
    code += '\n' + inspect.getsource(conductor)
    code += '\n' + inspect.getsource(openwhisk)
    code += '\n' + inspect.getsource(Compositions)
    code += '\n' + inspect.getsource(composer.serialize)
    code += '\n' + inspect.getsource(composer.Composition)
    code += '\n' + inspect.getsource(composer.get_value)
    code += '\n' + inspect.getsource(composer.get_params)
    code += '\n' + inspect.getsource(composer.set_params)
    code += '\n' + inspect.getsource(composer.retain_result)
    code += '\n' + inspect.getsource(composer.retain_nested_result)
    code += '\n' + inspect.getsource(composer.dec_count)
    code += '\n' + inspect.getsource(composer.set_nested_params)
    code += '\n' + inspect.getsource(composer.get_nested_params)
    code += '\n' + inspect.getsource(composer.set_nested_result)
    code += '\n' + inspect.getsource(composer.get_nested_result)
    code += '\n' + inspect.getsource(composer.retry_cond)

    import openwhisk as ow
    code += '\n' + inspect.getsource(ow.Client)
    code += '\n' + inspect.getsource(ow.BaseOperation)
    code += '\n' + inspect.getsource(ow.Resource)
    code += '\n' + inspect.getsource(ow.Action)
    code += '\n' + inspect.getsource(ow.parse_id_and_ns)
    code += '\n' + inspect.getsource(ow.parse_id)
    code += '\n' + inspect.getsource(ow.parse_namespace)

    code += 'def main(args):'
    code += '\n    return conductor(composition)(args)'

    annotations = [
        { 'key': 'conductor', 'value': str(composition['ast']) },
        { 'key': 'composerVersion', 'value': composition['version'] },
        { 'key': 'conductorVersion', 'value': __version__ },
        { 'key': 'provide-api-key', 'value': True },
        *composition["annotations"]
    ]

    return { 'name': composition['name'], 'action': { 'exec': { 'kind': 'python:3', 'code':code }, 'annotations': annotations, 'limits': composition['limits'] } }

def openwhisk(options):
    ''' return enhanced openwhisk client capable of deploying compositions '''

    # try to extract apihost and key first from whisk property file file and then from os.environ
    try:
        wskpropsPath = os.environ['WSK_CONFIG_FILE'] if 'WSK_CONFIG_FILE' in os.environ else os.path.expanduser('~/.wskprops')
        with open(wskpropsPath) as f:
            lines = f.readlines()

        options = dict(options)

        for line in lines:
            parts = line.strip().split('=')
            if len(parts) == 2:
                if parts[0] == 'APIHOST':
                    options['apihost'] = parts[1]
                elif parts[0] == 'AUTH':
                    options['api_key'] = parts[1]
    except:
        pass

    if '__OW_API_HOST' in os.environ:
        options['apihost'] = os.environ['__OW_API_HOST']

    if '__OW_API_KEY' in os.environ:
            options['api_key'] = os.environ['__OW_API_KEY']

    try:
        import openwhisk
        wsk = openwhisk.Client(options)
    except:
        wsk = Client(options)

    wsk.compositions = Compositions(wsk)
    return wsk

class Compositions:
    ''' management class for compositions '''
    def __init__(self, wsk):
        self.actions = wsk.actions

    def deploy(self, composition, overwrite):
        actions = composition.get('actions', [])
        actions.append(synthesize(composition))

        for action in actions:
            if overwrite:
                try:
                    self.actions.delete(action)
                except Exception:
                    pass
            self.actions.create(action)

        return actions

def conductor(composition): # main.
    wsk = None
    isObject = lambda x: isinstance(x, dict)

    # compile AST to FSM
    compiler = {}
    astnode = lambda f: compiler.setdefault(f.__name__[1:], f)

    @astnode
    def _sequence(parent, node):
        fsm = [{ 'parent': parent, 'type': 'pass' }]
        fsm.extend(compile(parent, *node['components']))
        return fsm

    @astnode
    def _action(parent, node):
        return [{ 'parent': parent, 'type': 'action', 'name': node['name'] }]

    @astnode
    def _asynchronous(parent, node):
        body = compile(parent, *node['components'])
        return [{ 'parent': parent, 'type': 'async', 'return': len(body) + 2}, *body, {'parent': parent, 'type': 'stop' }, {'parent': parent, 'type': 'pass' }]

    @astnode
    def _function(parent, node):
        return [{ 'parent': parent, 'type': 'function', 'exec': node['function']['exec'] }]

    @astnode
    def _ensure(parent, node):
        body = compile(parent, node['body'])
        finalizer = compile(parent, node['finalizer'])
        fsm = [{ 'parent': parent, 'type': 'try'}, *body, { 'parent': parent, 'type': 'exit' }, *finalizer]
        fsm[0]['catch'] = len(fsm) - len(finalizer)
        return fsm

    @astnode
    def _let(parent, node):
        body = compile(parent, *node['components'])
        return [{'parent': parent, 'type': 'let', 'let': node['declarations']}, *body, { 'parent': parent, 'type': 'exit' }]

    @astnode
    def _mask(parent, node):
        body = compile(parent, *node['components'])
        return [{'parent': parent, 'type': 'let', 'let': None}, *body, { 'parent': parent, 'type': 'exit' }]

    @astnode
    def _do(parent, node):
        handler = [ *compile(parent, node['handler']), {'parent': parent, 'type': 'pass'}]
        body = compile(parent, node['body'])
        fsm = [{ 'parent': parent, 'type': 'try' }, *body, { 'parent': parent, 'type': 'exit' }, *handler]
        fsm[0]['catch'] = len(fsm) - len(handler)
        fsm[len(fsm) - len(handler) - 1]['next'] = len(handler)
        return fsm

    @astnode
    def _when_nosave(parent, node):
        consequent = compile(parent, node['consequent'])
        alternate = [ *compile(parent, node['alternate']), { parent: 'parent', 'type': 'pass' }]
        fsm = [{ 'parent': parent, 'type': 'pass' },
            *compile(parent, node['test']),
            { 'parent': parent, 'type': 'choice', 'then': 1, 'else': len(consequent) + 1 },
            *consequent,
            *alternate]
        fsm[len(fsm) - len(alternate) - 1]['next'] = len(alternate)
        return fsm

    @astnode
    def _loop_nosave(parent, node):
        body = compile(parent, node['body'])
        test = compile(parent, node['test'])
        fsm = [{ 'parent': parent, 'type': 'pass' }, *test,
            { 'parent': parent, 'type': 'choice', 'then': 1, 'else': len(body) + 1 },
            *body, { parent: 'parent', 'type': 'pass' }]
        fsm[len(fsm) - 2]['next'] = 2 - len(fsm)
        return fsm

    @astnode
    def _doloop_nosave(parent, node):
        body = compile(parent, node['body'])
        test = compile(parent, node['test'])
        fsm = [{ 'parent': parent, 'type': 'pass' }, *body, *test,
               { 'parent': parent, 'type': 'choice', 'else': 1}, { parent: 'parent', 'type': 'pass' }]
        fsm[len(fsm) - 2]['then'] = 2 - len(fsm)
        return fsm

    def compile(parent, *node):
        nonlocal compiler
        if len(node) == 0:
            return [{'parent': parent, 'type': 'empty'}]
        if len(node) == 1:
            return compiler[node[0]['type']](node[0]['path'] if 'path' in node[0] else parent, node[0])
        return functools.reduce(lambda fsm, node: extends(fsm, compile(parent, node)), node, [])


    def extends(l, items):
        l.extend(items)
        return l

    fsm = compile('', composition)

    conductor = {}
    operator = lambda f: conductor.setdefault(f.__name__[1:], f)

    @operator
    def _choice(p, node, index, inspect, step):
        p['s']['state'] = index + (node['then'] if p['params']['value'] else node['else'])
        return None

    @operator
    def _try(p, node, index, inspect, step):
        p['s']['stack'].insert(0, { 'catch': index + node['catch'] })

    @operator
    def _let(p, node, index, inspect, step):
        p['s']['stack'].insert(0, { 'let': node['let'] }) # JSON.parse(JSON.stringify(jsonv.let))

    @operator
    def _exit(p, node, index, inspect, step):
        if len(p['s']['stack']) == 0:
            return internalError('pop from an empty stack')
        p['s']['stack'].pop(0)

    @operator
    def _action(p, node, index, inspect, step):
        return { 'method': 'action', 'action': node['name'], 'params': p['params'], 'state': { '$composer': p['s'] } }

    @operator
    def _function(p, node, index, inspect, step):
        result = None
        try:
            functionName = node['exec']['functionName'] if 'functionName' in node['exec'] else None
            result = run(node['exec']['code'], p, node['exec']['kind'], functionName)
        except Exception as error:
            result = { 'error': 'Function combinator threw an exception at AST node root'+node['parent']+' (see log for details)' }

        if callable(result):
            result = { 'error': 'Function combinator evaluated to a function type at AST node root'+node['parent']}

        # if a function has only side effects and no return value (or return None), return params
        p['params'] = p['params'] if result is None else result
        inspect_errors(p)
        return step(p)

    @operator
    def _empty(p, node, index, inspect, step):
        inspect_errors(p)

    @operator
    def _pass(p, node, index, inspect, step):
        pass

    @operator
    def _async(p, node, index, inspect, step):
        nonlocal wsk

        p['params']['$composer'] = { 'state': p['s']['state'], 'stack': [{ 'marker': True }] + p['s']['stack'] }
        p['s']['state'] = index + node['return']
        if wsk is None:
            wsk = openwhisk({ 'ignore_certs': True })
        try:
            response = wsk.actions.invoke({ 'name': os.getenv('__OW_ACTION_NAME'), 'params': p['params'] })
            result = { 'method': 'async', 'activationId': response['activationId'], 'sessionId': p['s']['session'] }

        except Exception as err:
            print(err) # invoke failed
            result = { 'error': 'Async combinator failed to invoke composition at AST node root'+node['parent']+' (see log for details)' }

        p['params'] = result
        inspect_errors(p)
        return step(p)

    def finish(q):
        return q['params'] if 'error' in q['params'] else { 'params': q['params'] }

    def encodeError(error):
        if isinstance(error, str) or not hasattr(error, "__getitem__"):
            return {
                'code': 500,
                'error': error
            }
        else:
            return {
                'code': error['code'] if isinstance(error['code'], int) else 500,
                'error': error['error'] if isinstance(error['error'], str) else (error['message'] if 'message' in error else 'An internal error occurred')
            }

    # error status codes
    #badRequest = lambda error: { 'code': 400, 'error': error }
    internalError = lambda error: encodeError(error)

    def inspect_errors(p):
        if not isObject(p['params']):
            p['params'] = { 'value': p['params'] }
        if 'error' in p['params']:
            p['params'] = { 'error': p['params']['error'] } # discard all fields but the error field
            p['s']['state'] = -1 # abort unless there is a handler in the stack
            while len(p['s']['stack']) > 0 and 'marker' not in p['s']['stack'][0]:
                first = p['s']['stack'][0]
                p['s']['stack'] = p['s']['stack'][1:]
                if 'catch' in first:
                    p['s']['state'] = first['catch']
                    if p['s']['state'] >= 0:
                        break

    def reduceRight(func, init, seq):
        if not seq:
            return init
        else:
            return func(reduceRight(func, init, seq[1:]), seq[0])

    def update(dict, dict2):
        dict.update(dict2)
        return dict

    # run function f on current stack
    def run(f, p, kind, functionName=None):
        # handle let/mask pairs
        view = []
        n = 0
        for frame in p['s']['stack']:
            if 'let' in frame and frame['let'] is None:
                n += 1
            elif 'let' in frame:
                if n == 0:
                    view.append(frame)
                else:
                    n -= 1
        # update value of topmost matching symbol on stack if any
        def set(symbol, value):
            lets = [element for element in view if 'let' in element and symbol in element['let']]
            if len(lets) > 0:
                element = lets[0]
                element['let'][symbol] = value # TODO: JSON.parse(JSON.stringify(value))

        # collapse stack for invocation
        env = reduceRight(lambda acc, cur: update(acc, cur['let']) if 'let' in cur and isinstance(cur['let'], dict) else acc, {}, view)
        if kind == 'python:3':
            main = '''exec(code + "\\n__out__['value'] = ''' + functionName + '''(env, args)", {'env': env, 'args': args, '__out__':__out__})'''
            code = f
        else: # lambda
            main = '''__out__['value'] = code(env, args)'''
            code = types.FunctionType(marshal.loads(base64.b64decode(bytearray(f, 'ASCII'))), {})

        try:
            out = {'value': None}
            exec(main, {'env': env, 'args': p['params'], 'code': code, '__out__': out})
            return out['value']
        finally:
            for name in env:
                set(name, env[name])

    def step(p):
        # final state, return composition result
        if p['s']['state'] < 0 or p['s']['state'] >= len(fsm):
            print('Entering final state')
            print(json.dumps(p['params']))
            return None

        # process one state
        node = fsm[p['s']['state']] # json definition for current state
        if 'path' in node:
            print('Entering composition'+node['path'])
        index = p['s']['state']
        p['s']['state'] = p['s']['state'] + node.get('next', 1)
        if not callable(conductor[node['type']]):
            return internalError('unexpected '+node['type']+' combinator')

        result = conductor[node['type']](p, node, index, inspect, step)
        return result if result is not None else step(p)


    def invoke(params):
        ''' do invocation '''
        pcomposer = params.get('$composer', {})
        if '$composer' in params:
            del params['$composer']
        pcomposer['session'] = pcomposer.get('session', os.getenv('__OW_ACTIVATION_ID'))

        # current state
        s = { 'state': 0, 'stack': [], 'resuming': True }
        s.update(pcomposer)
        p = { 's': s, 'params': params }

        if not isinstance(p['s']['state'], int):
            return internalError('state parameter is not a number')
        if not isinstance(p['s']['stack'], list):
            return internalError('stack parameter is not an array')

        if 'resuming' in pcomposer:
            inspect_errors(p) # handle error objects when resuming

        result = None
        try:
            result = step(p)
        except Exception as err:
            p['params'] = {'error': internalError(err)}

        return result if result is not None else finish(p)

    return invoke