%% verification_validation_engine.erl
%% Advanced verification and validation state machine
%% Multi-layered validation with formal methods and proof checking
-module(verification_validation_engine).
-behaviour(gen_statem).

-export([
    start_link/1,
    submit_for_verification/2,
    add_validation_rule/2,
    execute_formal_verification/2,
    proof_checking/2,
    property_verification/2,
    model_checking/2,
    static_analysis/2,
    dynamic_testing/2,
    compliance_checking/2,
    certification_process/2
]).

-export([init/1, callback_mode/0, terminate/3]).
-export([
    idle/3, preprocessing/3, static_verification/3, dynamic_verification/3,
    formal_verification/3, proof_checking/3, compliance_checking/3,
    certification/3, completed/3, failed/3
]).

-record(verification_data, {
    verification_id,
    subject_under_verification,
    verification_specification,
    validation_rules = [],
    verification_results = #{},
    proof_obligations = [],
    property_assertions = [],
    model_checking_results = #{},
    compliance_requirements = [],
    certification_criteria = #{},
    verification_timeline = [],
    quality_metrics = #{},
    evidence_collection = []
}).

%% Public API
start_link(Config) ->
    gen_statem:start_link(?MODULE, Config, []).

submit_for_verification(Pid, Subject) ->
    gen_statem:call(Pid, {submit, Subject}).

add_validation_rule(Pid, Rule) ->
    gen_statem:call(Pid, {add_rule, Rule}).

execute_formal_verification(Pid, Spec) ->
    gen_statem:call(Pid, {formal_verify, Spec}).

proof_checking(Pid, ProofObligation) ->
    gen_statem:call(Pid, {proof_check, ProofObligation}).

property_verification(Pid, Properties) ->
    gen_statem:call(Pid, {verify_properties, Properties}).

model_checking(Pid, Model) ->
    gen_statem:call(Pid, {model_check, Model}).

static_analysis(Pid, AnalysisType) ->
    gen_statem:call(Pid, {static_analysis, AnalysisType}).

dynamic_testing(Pid, TestSuite) ->
    gen_statem:call(Pid, {dynamic_test, TestSuite}).

compliance_checking(Pid, Standards) ->
    gen_statem:call(Pid, {compliance_check, Standards}).

certification_process(Pid, CertificationLevel) ->
    gen_statem:call(Pid, {certify, CertificationLevel}).

%% Gen_statem callbacks
init(Config) ->
    VerificationId = generate_verification_id(),
    Data = #verification_data{
        verification_id = VerificationId,
        verification_specification = maps:get(specification, Config, #{}),
        validation_rules = maps:get(rules, Config, []),
        compliance_requirements = maps:get(compliance, Config, []),
        certification_criteria = maps:get(certification, Config, #{})
    },
    {ok, idle, Data}.

callback_mode() -> state_functions.

%% States
idle({call, From}, {submit, Subject}, Data) ->
    NewData = Data#verification_data{subject_under_verification = Subject},
    {next_state, preprocessing, NewData, [{reply, From, {ok, preprocessing}}]};

idle({call, From}, {add_rule, Rule}, Data) ->
    Rules = Data#verification_data.validation_rules,
    NewData = Data#verification_data{validation_rules = [Rule | Rules]},
    {keep_state, NewData, [{reply, From, {ok, rule_added}}]};

idle(EventType, Event, Data) ->
    handle_common_verification_events(EventType, Event, Data, idle).

preprocessing(enter, _OldState, Data) ->
    % Preprocess and analyze subject
    analyze_verification_subject(Data),
    {keep_state_and_data, [{state_timeout, 5000, preprocessing_complete}]};

preprocessing(state_timeout, preprocessing_complete, Data) ->
    {next_state, static_verification, Data};

preprocessing(EventType, Event, Data) ->
    handle_common_verification_events(EventType, Event, Data, preprocessing).

static_verification(enter, _OldState, Data) ->
    % Perform static analysis
    execute_static_verification_suite(Data),
    {keep_state_and_data, [{state_timeout, 10000, static_complete}]};

static_verification({call, From}, {static_analysis, AnalysisType}, Data) ->
    Result = perform_static_analysis(AnalysisType, Data),
    {keep_state_and_data, [{reply, From, {ok, Result}}]};

static_verification(state_timeout, static_complete, Data) ->
    {next_state, dynamic_verification, Data};

static_verification(EventType, Event, Data) ->
    handle_common_verification_events(EventType, Event, Data, static_verification).

dynamic_verification(enter, _OldState, Data) ->
    % Perform dynamic testing
    execute_dynamic_verification_suite(Data),
    {keep_state_and_data, [{state_timeout, 15000, dynamic_complete}]};

dynamic_verification({call, From}, {dynamic_test, TestSuite}, Data) ->
    Result = execute_dynamic_test_suite(TestSuite, Data),
    {keep_state_and_data, [{reply, From, {ok, Result}}]};

dynamic_verification(state_timeout, dynamic_complete, Data) ->
    {next_state, formal_verification, Data};

dynamic_verification(EventType, Event, Data) ->
    handle_common_verification_events(EventType, Event, Data, dynamic_verification).

formal_verification(enter, _OldState, Data) ->
    % Perform formal verification
    execute_formal_verification_suite(Data),
    {keep_state_and_data, [{state_timeout, 20000, formal_complete}]};

formal_verification({call, From}, {formal_verify, Spec}, Data) ->
    Result = perform_formal_verification(Spec, Data),
    {keep_state_and_data, [{reply, From, {ok, Result}}]};

formal_verification({call, From}, {verify_properties, Properties}, Data) ->
    Result = verify_system_properties(Properties, Data),
    {keep_state_and_data, [{reply, From, {ok, Result}}]};

formal_verification({call, From}, {model_check, Model}, Data) ->
    Result = execute_model_checking(Model, Data),
    {keep_state_and_data, [{reply, From, {ok, Result}}]};

formal_verification(state_timeout, formal_complete, Data) ->
    {next_state, proof_checking, Data};

formal_verification(EventType, Event, Data) ->
    handle_common_verification_events(EventType, Event, Data, formal_verification).

proof_checking(enter, _OldState, Data) ->
    % Check proof obligations
    verify_proof_obligations(Data),
    {keep_state_and_data, [{state_timeout, 12000, proof_complete}]};

proof_checking({call, From}, {proof_check, ProofObligation}, Data) ->
    Result = check_proof_obligation(ProofObligation, Data),
    {keep_state_and_data, [{reply, From, {ok, Result}}]};

proof_checking(state_timeout, proof_complete, Data) ->
    {next_state, compliance_checking, Data};

proof_checking(EventType, Event, Data) ->
    handle_common_verification_events(EventType, Event, Data, proof_checking).

compliance_checking(enter, _OldState, Data) ->
    % Check compliance requirements
    verify_compliance_requirements(Data),
    {keep_state_and_data, [{state_timeout, 8000, compliance_complete}]};

compliance_checking({call, From}, {compliance_check, Standards}, Data) ->
    Result = check_compliance_standards(Standards, Data),
    {keep_state_and_data, [{reply, From, {ok, Result}}]};

compliance_checking(state_timeout, compliance_complete, Data) ->
    case all_verifications_passed(Data) of
        true -> {next_state, certification, Data};
        false -> {next_state, failed, Data}
    end;

compliance_checking(EventType, Event, Data) ->
    handle_common_verification_events(EventType, Event, Data, compliance_checking).

certification(enter, _OldState, Data) ->
    % Perform certification process
    execute_certification_process(Data),
    {keep_state_and_data, [{state_timeout, 10000, certification_complete}]};

certification({call, From}, {certify, Level}, Data) ->
    Result = perform_certification(Level, Data),
    {keep_state_and_data, [{reply, From, {ok, Result}}]};

certification(state_timeout, certification_complete, Data) ->
    {next_state, completed, Data};

certification(EventType, Event, Data) ->
    handle_common_verification_events(EventType, Event, Data, certification).

completed({call, From}, _Request, _Data) ->
    {keep_state_and_data, [{reply, From, {ok, verification_completed}}]};

completed(EventType, Event, Data) ->
    handle_common_verification_events(EventType, Event, Data, completed).

failed({call, From}, _Request, _Data) ->
    {keep_state_and_data, [{reply, From, {error, verification_failed}}]};

failed(EventType, Event, Data) ->
    handle_common_verification_events(EventType, Event, Data, failed).

handle_common_verification_events(_EventType, _Event, _Data, _State) ->
    keep_state_and_data.

terminate(_Reason, _StateName, _Data) -> ok.

%% Internal functions (placeholder implementations)
generate_verification_id() -> verification_id.
analyze_verification_subject(_Data) -> ok.
execute_static_verification_suite(_Data) -> ok.
perform_static_analysis(_Type, _Data) -> static_analysis_result.
execute_dynamic_verification_suite(_Data) -> ok.
execute_dynamic_test_suite(_Suite, _Data) -> test_result.
execute_formal_verification_suite(_Data) -> ok.
perform_formal_verification(_Spec, _Data) -> formal_result.
verify_system_properties(_Properties, _Data) -> properties_result.
execute_model_checking(_Model, _Data) -> model_check_result.
verify_proof_obligations(_Data) -> ok.
check_proof_obligation(_Obligation, _Data) -> proof_result.
verify_compliance_requirements(_Data) -> ok.
check_compliance_standards(_Standards, _Data) -> compliance_result.
all_verifications_passed(_Data) -> true.
execute_certification_process(_Data) -> ok.
perform_certification(_Level, _Data) -> certification_result.