"""
SMT-based Model Checking Module for RS with Concentrations and Context Automaton
"""

from z3 import *
from time import time
from sys import stdout
from itertools import chain
import resource
from colour import *

from logics import rsLTL_Encoder

# def simplify(x):
#     return x


class SmtCheckerRSC(object):

    def __init__(self, rsca):

        rsca.sanity_check()

        if not rsca.is_with_concentrations():
            raise RuntimeError("RS and CA with concentrations expected")

        self.rs = rsca.rs
        self.ca = rsca.ca

        self.initialise()

    def initialise(self):
        """Initialises all the variables used by the checker"""

        self.v = []
        self.v_ctx = []
        self.ca_state = []
        self.next_level_to_encode = 0

        self.loop_position = Int("loop_position")

        self.solver = Solver()  # For("QF_FD")

        self.verification_time = None

    def reset(self):
        """Reinitialises the state of the checker"""

        self.initialise()

    def prepare_all_variables(self):
        """Encodes all the variables"""

        self.prepare_state_variables()
        self.prepare_context_variables()
        self.next_level_to_encode += 1

    def prepare_context_variables(self):
        """Encodes all the context variables"""

        level = self.next_level_to_encode

        variables = []
        for entity in self.rs.background_set:
            variables.append(Int("C"+str(level)+"_"+entity))

        self.v_ctx.append(variables)

    def prepare_state_variables(self):
        """Encodes all the state variables"""

        level = self.next_level_to_encode

        variables = []
        for entity in self.rs.background_set:
            variables.append(Int("L"+str(level)+"_"+entity))
        self.v.append(variables)

        self.ca_state.append(Int("CA"+str(level)+"_state"))

    def enc_concentration_levels_assertion(self, level):
        """Encodes assertions that (some) variables need to be >0

        We do not need to actually control all the variables,
        only those that can possibly go below 0.
        """

        enc_nz = True

        for e_i in range(len(self.rs.background_set)):
            v = self.v[level][e_i]
            v_ctx = self.v_ctx[level][e_i]
            e_max = self.rs.get_max_concentration_level(e_i)
            enc_nz = simplify(
                And(enc_nz, v >= 0, v_ctx >= 0, v <= e_max, v_ctx <= e_max))

        return enc_nz

    def enc_init_state(self, level):
        """Encodes the initial state at the given level"""

        rs_init_state_enc = True

        for v in self.v[level]:
            # the initial concentration levels are zeroed
            rs_init_state_enc = simplify(And(rs_init_state_enc, v == 0))

        ca_init_state_enc = self.ca_state[level] == self.ca.get_init_state_id()

        init_state_enc = simplify(And(rs_init_state_enc, ca_init_state_enc))

        return init_state_enc

    def enc_produced_concentration(self, level, prod_entity):
        """Encodes the produced concentrations for the given level and entity"""

        rcts_for_prod_entity = []
        if prod_entity in self.rs.get_reactions_by_product():
            rcts_for_prod_entity = self.rs.get_reactions_by_product()[
                prod_entity]

        meta_reactions = []
        if prod_entity in self.rs.meta_reactions:
            meta_reactions = self.rs.meta_reactions[prod_entity]

        permanency_inhibition = None
        if prod_entity in self.rs.permanent_entities:
            permanency_inhibition = self.rs.permanent_entities[prod_entity]

        if rcts_for_prod_entity == [] and meta_reactions == []:
            # this should never happen
            return simplify(self.v[level+1][prod_entity] == 0)

        enc_enabledness = False

        # ----------- ordinary reactions --------------------------------------------

        enc_rct_prod = False

        enc_ordinary_reactions_enabledness = False

        for reactants, inhibitors, products in rcts_for_prod_entity:

            enc_reactants = True
            for reactant, concentration in reactants:
                enc_reactants = simplify(And(enc_reactants, Or(
                    self.v[level][reactant] >= concentration, self.v_ctx[level][reactant] >= concentration)))

            enc_inhibitors = True
            for inhibitor, concentration in inhibitors:
                enc_inhibitors = simplify(And(enc_inhibitors, And(
                    self.v[level][inhibitor] < concentration, self.v_ctx[level][inhibitor] < concentration)))

            enc_rct_enabled = And(enc_reactants, enc_inhibitors)
            enc_products = self.v[level+1][products[0][0]] == products[0][1]
            enc_rct_prod = simplify(
                If(enc_rct_enabled, enc_products, enc_rct_prod))
            enc_enabledness = simplify(Or(enc_enabledness, enc_rct_enabled))

            enc_ordinary_reactions_enabledness = simplify(
                Or(enc_ordinary_reactions_enabledness, enc_rct_enabled))

        # -------- meta reactions ---------------------------------------------------

        for r_type, command_entity, reactants, inhibitors in meta_reactions:

            # command entity is e.g. 'inc' for incrementation operation
            # (inc,W) gives us the value W by which the given entity's value should be incremented

            enc_reactants = True
            enc_inhibitors = True

            for reactant, concentration in reactants:
                enc_reactants = simplify(And(enc_reactants, Or(
                    self.v[level][reactant] >= concentration, self.v_ctx[level][reactant] >= concentration)))

            # command entity needs to be present (with concentration level > 0) in order to perform the operation
            enc_reactants = simplify(And(enc_reactants, Or(
                self.v[level][command_entity] > 0, self.v_ctx[level][command_entity] > 0)))

            for inhibitor, concentration in inhibitors:
                enc_inhibitors = simplify(And(enc_inhibitors, And(
                    self.v[level][inhibitor] < concentration, self.v_ctx[level][inhibitor] < concentration)))

            if r_type == "inc":
                value_after_inc = If(
                    self.v[level][prod_entity] > self.v_ctx[level]
                    [prod_entity],
                    self.v[level][prod_entity],
                    self.v_ctx[level][prod_entity]) + If(
                    self.v[level][command_entity] > self.
                    v_ctx[level][command_entity],
                    self.v[level][command_entity],
                    self.v_ctx[level][command_entity])
                enc_products = self.v[level+1][prod_entity] == value_after_inc

            elif r_type == "dec":
                value_after_dec = simplify(
                    If(
                        self.v[level][prod_entity] >
                        self.v_ctx[level]
                        [prod_entity],
                        self.v[level][prod_entity],
                        self.v_ctx[level]
                        [prod_entity]) -
                    If(
                        self.v[level]
                        [command_entity] > self.
                        v_ctx[level][command_entity],
                        self.v[level]
                        [command_entity],
                        self.v_ctx[level]
                        [command_entity]))
                enc_products = self.v[level+1][prod_entity] == If(
                    value_after_dec < 0, 0, value_after_dec)

            else:
                raise RuntimeError(
                    "Unknown meta-reaction type: " + repr(r_type))

            enc_meta_reaction_enabledness = And(
                enc_reactants, enc_inhibitors,
                Not(enc_ordinary_reactions_enabledness))
            enc_enabledness = simplify(
                Or(enc_enabledness, enc_meta_reaction_enabledness))
            enc_rct_prod = simplify(Or(enc_rct_prod, And(
                enc_meta_reaction_enabledness, enc_products)))

        # -----------------------------------------------------------------------------

        if not permanency_inhibition == None:

            enc_reactants = Or(self.v[level][prod_entity] >= concentration,
                               self.v_ctx[level][prod_entity] >= concentration)

            enc_inhibitors = True
            for inhibitor, concentration in permanency_inhibition:
                enc_inhibitors = simplify(And(enc_inhibitors, And(
                    self.v[level][inhibitor] < concentration, self.v_ctx[level][inhibitor] < concentration)))
            enc_products = simplify(
                self.v[level + 1][prod_entity] ==
                If(
                    self.v[level][prod_entity] > self.v_ctx[level]
                    [prod_entity],
                    self.v[level][prod_entity],
                    self.v_ctx[level][prod_entity]))

            enc_permanency_enabledness = And(
                enc_reactants, enc_inhibitors,
                Not(enc_ordinary_reactions_enabledness))
            enc_enabledness = simplify(
                Or(enc_enabledness, enc_permanency_enabledness))
            enc_permanency = And(enc_permanency_enabledness, enc_products)
            enc_rct_prod = simplify(Or(enc_rct_prod, enc_permanency))

        # -----------------------------------------------------------------------------

        enc_when_to_produce_zero_conc = simplify(
            And(Not(enc_enabledness), self.v[level+1][prod_entity] == 0))

        enc_rct_prod = Or(enc_rct_prod, enc_when_to_produce_zero_conc)
        return enc_rct_prod

    def enc_transition_relation(self, level):
        return simplify(
            And(self.enc_rs_trans(level),
                self.enc_automaton_trans(level)))

    def enc_rs_trans(self, level):
        """Encodes the transition relation"""

        unused_entities = set(range(len(self.rs.background_set)))

        enc_trans = True

        reactions = self.rs.get_reactions_by_product()
        meta_reactions = self.rs.meta_reactions

        for prod_entity in chain(reactions, meta_reactions):
            unused_entities.discard(prod_entity)
            enc_trans = simplify(
                And(enc_trans, self.enc_produced_concentration(level, prod_entity)))

        for prod_entity in unused_entities:
            enc_trans = simplify(
                And(enc_trans, self.v[level+1][prod_entity] == 0))

        return enc_trans

    def enc_automaton_trans(self, level):
        """Encodes the transition relation for the context automaton"""

        enc_trans = False

        for src, ctx, dst in self.ca.transitions:
            src_enc = self.ca_state[level] == src
            dst_enc = self.ca_state[level+1] == dst

            all_ent = set(range(len(self.rs.background_set)))

            incl_ctx = set([e for e, c in ctx])
            excl_ctx = all_ent - incl_ctx

            ctx_enc = True

            for e, c in ctx:
                ctx_enc = simplify(And(ctx_enc, self.v_ctx[level][e] == c))

            for e in excl_ctx:
                ctx_enc = simplify(And(ctx_enc, self.v_ctx[level][e] == 0))

            cur_trans = simplify(And(src_enc, ctx_enc, dst_enc))
            enc_trans = simplify(Or(enc_trans, cur_trans))

        return enc_trans

    def enc_exact_state(self, level, state):
        """Encodes the state at the given level with the exact concentration values"""

        raise RuntimeError("Should not be used with RSC")

    def enc_min_state(self, level, state):
        """Encodes the state at the given level with the minimal required concentration levels"""

        enc = True
        for ent, conc in state:
            e_id = self.rs.get_entity_id(ent)
            enc = And(enc, self.v[level][e_id] >= conc)

        return simplify(enc)

    def enc_state_with_blocking(self, level, prop):
        """Encodes the state at the given level with blocking certain concentrations"""

        required, blocked = prop

        enc = True
        for ent, conc in required:
            e_id = self.rs.get_entity_id(ent)
            enc = And(enc, self.v[level][e_id] >= conc)

        for ent, conc in blocked:
            e_id = self.rs.get_entity_id(ent)
            enc = And(enc, self.v[level][e_id] < conc)

        return simplify(enc)

    def decode_witness(self, max_level, print_model=False):

        m = self.solver.model()

        if print_model:
            print(m)

        for level in range(max_level+1):

            print("\n{: >70}".format("[ level=" + repr(level) + " ]"))

            print("  State: {", end=""),
            for var_id in range(len(self.v[level])):
                var_rep = repr(m[self.v[level][var_id]])
                if not var_rep.isdigit():
                    raise RuntimeError(
                        "unexpected: representation is not a positive integer")
                if int(var_rep) > 0:
                    print(
                        " " + self.rs.get_entity_name(var_id) + "=" + var_rep,
                        end="")
                # print(" " + repr(m[self.v[level][var_id]]), end="")
            print(" }")

            if level != max_level:
                print("  Context set: ", end="")
                print("{", end="")
                for var_id in range(len(self.v[level])):
                    var_rep = repr(m[self.v_ctx[level][var_id]])
                    if not var_rep.isdigit():
                        raise RuntimeError(
                            "unexpected: representation is not a positive integer")
                    if int(var_rep) > 0:
                        print(
                            " " + self.rs.get_entity_name(var_id) + "=" + var_rep,
                            end="")
                print(" }")

    def check_rsltl(
            self, formula, print_witness=True, print_time=True, print_mem=True,
            max_level=None):
        """Bounded Model Checking for rsLTL properties"""

        self.reset()

        print("[" + colour_str(C_BOLD, "i") +
              "] Running rsLTL bounded model checking")
        print("[" + colour_str(C_BOLD, "i") + "] Formula: " + str(formula))

        if print_time:
            # start = time()
            start = resource.getrusage(resource.RUSAGE_SELF).ru_utime

        self.prepare_all_variables()
        self.solver.add(self.enc_init_state(0))
        self.current_level = 0

        self.prepare_all_variables()

        self.solver.add(self.enc_concentration_levels_assertion(0))

        encoder = rsLTL_Encoder(self)
        encoder.load_variables(
            var_rs=self.v,
            var_ctx=self.v_ctx,
            var_loop_pos=self.loop_position)

        while True:
            self.prepare_all_variables()
            self.solver.add(
                self.enc_concentration_levels_assertion(
                    self.current_level + 1))

            print(
                "\n{:-^70}".format("[ Working at level=" + str(self.current_level) + " ]"))
            stdout.flush()

            # reachability test:
            self.solver.push()

            print("[" + colour_str(C_BOLD, "i") +
                  "] Generating the formula encoding...")

            f = encoder.get_encoding(formula, self.current_level)
            ncalls = encoder.get_ncalls()

            print("[" + colour_str(C_BOLD, "i") + "] Cache hits: " +
                  str(encoder.get_cache_hits()) + ", encode calls: " +
                  str(ncalls[0]) + " (approx: " + str(ncalls[1]) + ")")
            print("[" + colour_str(C_BOLD, "i") +
                  "] Adding the formula to the solver...")

            encoder.flush_cache()
            self.solver.add(f)

            print("[" + colour_str(C_BOLD, "i") +
                  "] Adding the loops encoding...")
            self.solver.add(self.get_loop_encodings())

            result = self.solver.check()
            if result == sat:
                print(
                    "[" + colour_str(C_BOLD, "+") + "] " +
                    colour_str(
                        C_GREEN, "SAT at level=" + str(self.current_level)))
                if print_witness:
                    print("\n{:=^70}".format("[ WITNESS ]"))
                    self.decode_witness(self.current_level)
                break
            else:
                self.solver.pop()

            print("[" + colour_str(C_BOLD, "i") +
                  "] Unrolling the transition relation")
            self.solver.add(self.enc_transition_relation(self.current_level))

            print(
                "{:->70}".format("[ level=" + str(self.current_level) + " done ]"))
            self.current_level += 1

            if not max_level is None and self.current_level > max_level:
                print("Stopping at level=" + str(max_level))
                break

        if print_time:
            # stop = time()
            stop = resource.getrusage(resource.RUSAGE_SELF).ru_utime
            self.verification_time = stop-start
            print()
            print(
                "\n[i] {: >60}".format(
                    " Time: " + repr(self.verification_time) + " s"))

        if print_mem:
            print(
                "[i] {: >60}".format(
                    " Memory: " +
                    repr(
                        resource.getrusage(resource.RUSAGE_SELF).ru_maxrss /
                        (1024 * 1024)) + " MB"))

    def dummy_unroll(self, levels):
        """Unrolls the variables for testing purposes"""

        self.current_level = -1
        for i in range(levels+1):
            self.prepare_all_variables()
            self.current_level += 1

        print(C_MARK_INFO + " Dummy Unrolling done.")

    def state_equality(self, level_A, level_B):
        """Encodes equality of two states at two different levels"""

        eq_enc = True

        for e_i in range(len(self.rs.background_set)):
            e_i_equality = self.v[level_A][e_i] == self.v[level_B][e_i]
            eq_enc = simplify(And(eq_enc, e_i_equality))

        eq_enc_ctxaut = self.ca_state[level_A] == self.ca_state[level_B]
        eq_enc = simplify(And(eq_enc, eq_enc_ctxaut))

        return eq_enc

    def get_loop_encodings(self):

        k = self.current_level
        loop_var = self.loop_position

        loop_enc = True

        """
        (loop_var == i) means that there is a loop taking back to the state (i-1)
        
        Therefore, the encoding starts at 1, not at 0.
        """

        for i in range(1, k+1):
            loop_enc = simplify(And(loop_enc, Implies(
                loop_var == i, self.state_equality(i-1, k))))

        return loop_enc

    def check_reachability(self, state, print_witness=True,
                           print_time=True, print_mem=True, max_level=1000):
        """Main testing function"""

        self.reset()

        if print_time:
            # start = time()
            start = resource.getrusage(resource.RUSAGE_SELF).ru_utime

        self.prepare_all_variables()
        self.solver.add(self.enc_init_state(0))
        self.current_level = 0

        self.prepare_all_variables()

        self.solver.add(self.enc_concentration_levels_assertion(0))

        while True:
            self.prepare_all_variables()
            self.solver.add(
                self.enc_concentration_levels_assertion(
                    self.current_level + 1))

            print(
                "\n{:-^70}".format("[ Working at level=" + str(self.current_level) + " ]"))
            stdout.flush()

            # reachability test:
            print("[" + colour_str(C_BOLD, "i") +
                  "] Adding the reachability test...")
            self.solver.push()

            self.solver.add(self.enc_state_with_blocking(
                self.current_level, state))

            result = self.solver.check()
            if result == sat:
                print(
                    "[" + colour_str(C_BOLD, "+") + "] " +
                    colour_str(
                        C_GREEN, "SAT at level=" + str(self.current_level)))
                if print_witness:
                    print("\n{:=^70}".format("[ WITNESS ]"))
                    self.decode_witness(self.current_level)
                break
            else:
                self.solver.pop()

            print("[" + colour_str(C_BOLD, "i") +
                  "] Unrolling the transition relation")
            self.solver.add(self.enc_transition_relation(self.current_level))

            print(
                "{:->70}".format("[ level=" + str(self.current_level) + " done ]"))
            self.current_level += 1

            if self.current_level > max_level:
                print("Stopping at level=" + str(max_level))
                break

        if print_time:
            # stop = time()
            stop = resource.getrusage(resource.RUSAGE_SELF).ru_utime
            self.verification_time = stop-start
            print()
            print(
                "\n[i] {: >60}".format(
                    " Time: " + repr(self.verification_time) + " s"))

        if print_mem:
            print(
                "[i] {: >60}".format(
                    " Memory: " +
                    repr(
                        resource.getrusage(resource.RUSAGE_SELF).ru_maxrss /
                        (1024 * 1024)) + " MB"))

    def get_verification_time(self):
        return self.verification_time

    def show_encoding(self, state, print_witness=True,
                      print_time=False, print_mem=False, max_level=100):
        """Encoding debug function"""

        self.reset()

        self.prepare_all_variables()
        init_s = self.enc_init_state(0)
        print(init_s)
        self.solver.add(init_s)
        self.current_level = 0

        self.prepare_all_variables()

        while True:
            self.prepare_all_variables()

            print(
                "-----[ Working at level=" + str(self.current_level) + " ]-----")
            stdout.flush()

            # reachability test:
            print("[i] Adding the reachability test...")
            self.solver.push()

            s = self.enc_min_state(self.current_level, state)
            print("Test: ", s)

            self.solver.add(s)

            result = self.solver.check()
            if result == sat:
                print(
                    "\n[+] " +
                    colour_str(
                        C_RED, "SAT at level=" + str(self.current_level)))
                if print_witness:
                    self.decode_witness(self.current_level)
                break
            else:
                self.solver.pop()

            print("[i] Unrolling the transition relation")
            t = self.enc_transition_relation(self.current_level)
            print(t)
            self.solver.add(t)

            print("-----[ level=" + str(self.current_level) + " done ]")
            self.current_level += 1

            if self.current_level > max_level:
                print("Stopping at level=" + str(max_level))
                break
            else:
                x = input("Next level? ")
                x = x.lower()
                if not (x == "y" or x == "yes"):
                    break
