# -*- coding: utf-8 -*-
##############################################################################
#
#    GNU Health: The Free Health and Hospital Information System
#    Copyright (C) 2008-2021 Luis Falcon <lfalcon@gnusolidario.org>
#    Copyright (C) 2011-2021 GNU Solidario <health@gnusolidario.org>
#
#
#    This program is free software: you can redistribute it and/or modify
#    it under the terms of the GNU General Public License as published by
#    the Free Software Foundation, either version 3 of the License, or
#    (at your option) any later version.
#
#    This program is distributed in the hope that it will be useful,
#    but WITHOUT ANY WARRANTY; without even the implied warranty of
#    MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
#    GNU General Public License for more details.
#
#    You should have received a copy of the GNU General Public License
#    along with this program.  If not, see <http://www.gnu.org/licenses/>.
#
##############################################################################
from datetime import datetime
from trytond.model import ModelView, ModelSQL, fields
from trytond.transaction import Transaction
from trytond.rpc import RPC
from trytond.pool import Pool
from trytond.wizard import Wizard, StateAction, StateView, Button
from trytond.pyson import Eval, Not, Bool, PYSONEncoder, Equal, And, Or
import hashlib
import json
from uuid import uuid4

__all__ = ['LabTest']


class LabTest(ModelSQL, ModelView):
    'Lab Test'
    __name__ = 'gnuhealth.lab'

    STATES = {'readonly': Eval('state') == 'validated'}

    serializer = fields.Text('Doc String', readonly=True)

    document_digest = fields.Char('Digest', readonly=True,
        help="Original Document Digest")

    state = fields.Selection([
        ('draft', 'Draft'),
        ('done', 'Done'),
        ('validated', 'Validated'),
        ], 'State', readonly=True, sort=False)


    digest_status = fields.Function(fields.Boolean('Altered',
        help="This field will be set whenever parts of" \
        " the main original document has been changed." \
        " Please note that the verification is done only on selected" \
        " fields." ),
        'check_digest')

    serializer_current = fields.Function(fields.Text('Current Doc',
            states={
            'invisible': Not(Bool(Eval('digest_status'))),
            }),
        'check_digest')


    digest_current = fields.Function(fields.Char('Current Hash',
            states={
            'invisible': Not(Bool(Eval('digest_status'))),
            }),
        'check_digest')

    digital_signature = fields.Text('Digital Signature', readonly=True)

    done_by = fields.Many2One(
        'gnuhealth.healthprofessional',
        'Done by', readonly=True, help='Professional who processes this'
        ' lab test',
        states = STATES )

    done_date = fields.DateTime('Finished on', readonly=True,
        states = STATES )

    validated_by = fields.Many2One(
        'gnuhealth.healthprofessional',
        'Validated by', readonly=True, help='Professional who validates this'
        ' lab test',
        states = STATES )

    validation_date = fields.DateTime('Validated on', readonly=True,
        states = STATES )

    historize = fields.Boolean("Historize",
                    states = STATES,
                    depends=['pathology'],
                    help='If this flag is set'
                    ' the a new health condition will be added'
                    ' to the patient history.'
                    ' Unset it if this lab test is in the context'
                    ' of a pre-existing condition of the patient.'
                    ' The condition will be created when the lab test'
                    ' is confirmed and validated')

    @staticmethod
    def default_state():
        return 'draft'

    @staticmethod
    def default_historize():
        return False

    @fields.depends('pathology')
    def on_change_with_historize(self):
        if (self.pathology):
            return True

    @classmethod
    def __setup__(cls):
        super(LabTest, cls).__setup__()
        cls._buttons.update({
            'generate_document': {
                'invisible': Not(Equal(Eval('state'), 'draft')),
                },
            'set_to_draft': {
                'invisible': Not(Equal(Eval('state'), 'done')),
                },
            'sign_document': {
                'invisible': Not(Equal(Eval('state'), 'done')),
                },
            })
        ''' Allow calling the set_signature method via RPC '''
        cls.__rpc__.update({
                'set_signature': RPC(readonly=False),
                })

    @classmethod
    @ModelView.button
    def generate_document(cls, documents):
        pool = Pool()
        HealthProfessional = pool.get('gnuhealth.healthprofessional')

        document = documents[0]


        # Set the document to "Done"
        # and write the name of the signing health professional

        hp = HealthProfessional.get_health_professional()
        if not hp:
            cls.raise_user_error(
                "No health professional associated to this user !")

        serial_doc=cls.get_serial(document)

        cls.write(documents, {
            'done_by': hp,
            'done_date': datetime.now(),
            'state': 'done',})

    @classmethod
    @ModelView.button
    def set_to_draft(cls, documents):
        document = documents[0]

        cls.write(documents, {
            'state': 'draft',})

    @classmethod
    @ModelView.button
    def sign_document(cls, documents):
        pool = Pool()
        HealthProfessional = pool.get('gnuhealth.healthprofessional')

        document = documents[0]

        # Validate / generate digest for the document
        # and write the name of the signing health professional

        hp = HealthProfessional.get_health_professional()
        if not hp:
            cls.raise_user_error(
                "No health professional associated to this user !")

        serial_doc=cls.get_serial(document)

        cls.write(documents, {
            'serializer': serial_doc,
            'document_digest': HealthCrypto().gen_hash(serial_doc),
            'validated_by': hp,
            'validation_date': datetime.now(),
            'state': 'validated',})

        # Create lab PoL if the person has a federation account.
        if (document.patient.name.federation_account):
            cls.create_lab_pol (document)

        # Create Health condition to the patient
        # if there is a confirmed pathology associated and
        # validated to the lab test result
        # The flag historize must also be set
        if (document.pathology and document.historize):
            cls.create_health_condition (document)

    @classmethod
    def get_serial(cls,document):

        analyte_line=[]

        for line in document.critearea:
            line_elements=[line.name or '',
                line.result or '',
                line.result_text or '',
                line.remarks or '']

            analyte_line.append(line_elements)

        data_to_serialize = {
            'Lab_test': str(document.name) or '',
            'Test': str(document.test.rec_name) or '',
            'HP': str(document.requestor.rec_name),
            'Patient': str(document.patient.rec_name),
            'Patient_ID': str(document.patient.name.ref) or '',
            'Analyte_line': str(analyte_line),
             }

        serialized_doc = str(HealthCrypto().serialize(data_to_serialize))

        return serialized_doc

    @classmethod
    def set_signature(cls, data, signature):
        """
        Set the clearsigned signature
        """

        doc_id = data['id']

        cls.write([cls(doc_id)], {
            'digital_signature': signature,
            })


    def check_digest (self,name):
        result=''
        serial_doc=self.get_serial(self)
        if (name == 'digest_status' and self.document_digest):
            if (HealthCrypto().gen_hash(serial_doc) == self.document_digest):
                result = False
            else:
                ''' Return true if the document has been altered'''
                result = True
        if (name=='digest_current'):
            result = HealthCrypto().gen_hash(serial_doc)

        if (name=='serializer_current'):
            result = serial_doc

        return result

    # Hide the group holding validation information when state is
    # not validated

    @classmethod
    def view_attributes(cls):
        return [('//group[@id="document_digest"]', 'states', {
                'invisible': Not(Eval('state') == 'validated'),
                })]

    @classmethod
    def create_health_condition(cls, lab_info):
        """ Create the health condition when specified and 
            validated in the lab test
        """
        HealthCondition = Pool().get('gnuhealth.patient.disease')
        health_condition = []

        vals = {
            'name': lab_info.patient.id,
            'pathology': lab_info.pathology,
            'diagnosed_date': lab_info.date_analysis.date(),
            'lab_confirmed': True,
            'lab_test': lab_info.id,
            'extra_info': lab_info.diagnosis,
            'healthprof': lab_info.requestor
            }

        health_condition.append(vals)
        HealthCondition.create(health_condition)


    @classmethod
    def create_lab_pol(cls,lab_info):
        """ Adds an entry in the person Page of Life
            related to this person lab
        """
        Pol = Pool().get('gnuhealth.pol')
        pol = []

        test_lines = ""
        for line in lab_info.critearea:
            test_lines = test_lines + line.rec_name + "\n"

        vals = {
            'page': str(uuid4()),
            'person': lab_info.patient.name.id,
            'page_date': lab_info.date_analysis,
            'federation_account': \
                lab_info.patient.name.federation_account,
            'page_type':'medical',
            'medical_context':'lab',
            'relevance':'important',
            'info': lab_info.analytes_summary,
            'author': lab_info.requestor and \
                lab_info.requestor.rec_name
            }

        pol.append(vals)
        Pol.create(pol)


class HealthCrypto:
    """ GNU Health Cryptographic functions
    """

    def serialize(self,data_to_serialize):
        """ Format to JSON """

        json_output = \
            json.dumps(data_to_serialize,ensure_ascii=False)
        return json_output

    def gen_hash(self, serialized_doc):
        return hashlib.sha512(serialized_doc.encode('utf-8')).hexdigest()


