/*
Copyright (c) 2014 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.

Author: Leonardo de Moura
*/
#include <unordered_map>
#include <string>
#include "util/sstream.h"
#include "util/optional.h"
#include "kernel/instantiate.h"
#include "kernel/type_checker.h"
#include "kernel/default_converter.h"
#include "library/annotation.h"
#include "library/string.h"
#include "library/explicit.h"
#include "library/placeholder.h"
#include "library/num.h"
#include "library/constants.h"
#include "library/projection.h"
#include "library/kernel_serializer.h"
#include "library/tactic/expr_to_tactic.h"

namespace lean {
static expr * g_and_then_tac_fn   = nullptr;
static expr * g_or_else_tac_fn    = nullptr;
static expr * g_id_tac_fn         = nullptr;
static expr * g_repeat_tac_fn     = nullptr;
static expr * g_determ_tac_fn     = nullptr;
static expr * g_tac_type          = nullptr;
static expr * g_builtin_tac       = nullptr;
static expr * g_fixpoint_tac      = nullptr;
expr const & get_and_then_tac_fn() { return *g_and_then_tac_fn; }
expr const & get_or_else_tac_fn() { return *g_or_else_tac_fn; }
expr const & get_id_tac_fn() { return *g_id_tac_fn; }
expr const & get_determ_tac_fn() { return *g_determ_tac_fn; }
expr const & get_repeat_tac_fn() { return *g_repeat_tac_fn; }
expr const & get_tactic_type() { return *g_tac_type; }
expr const & get_builtin_tac() { return *g_builtin_tac; }

typedef std::unordered_map<name, expr_to_tactic_fn, name_hash, name_eq> expr_to_tactic_map;
static expr_to_tactic_map * g_map = nullptr;

expr_to_tactic_map & get_expr_to_tactic_map() {
    return *g_map;
}

void register_tac(name const & n, expr_to_tactic_fn const & fn) {
    get_expr_to_tactic_map().insert(mk_pair(n, fn));
}

bool has_tactic_decls(environment const & env) {
    try {
        type_checker tc(env);
        return
            tc.infer(*g_builtin_tac).first     == *g_tac_type &&
            tc.infer(*g_and_then_tac_fn).first == *g_tac_type >> (*g_tac_type >> *g_tac_type) &&
            tc.infer(*g_or_else_tac_fn).first  == *g_tac_type >> (*g_tac_type >> *g_tac_type) &&
            tc.infer(*g_repeat_tac_fn).first   == *g_tac_type >> *g_tac_type;
    } catch (exception &) {
        return false;
    }
}

static expr * g_tactic_expr_type = nullptr;
static expr * g_tactic_expr_builtin = nullptr;
static expr * g_tactic_expr_list_type = nullptr;
static expr * g_tactic_identifier_type = nullptr;
static expr * g_tactic_using_expr_type = nullptr;

expr const & get_tactic_expr_type() { return *g_tactic_expr_type; }
expr const & get_tactic_expr_builtin() { return *g_tactic_expr_builtin; }
expr const & get_tactic_expr_list_type() { return *g_tactic_expr_list_type; }
expr const & get_tactic_identifier_type() { return *g_tactic_identifier_type; }
expr const & get_tactic_using_expr_type() { return *g_tactic_using_expr_type; }

static std::string * g_tactic_expr_opcode = nullptr;
static std::string * g_tactic_opcode = nullptr;

std::string const & get_tactic_expr_opcode() { return *g_tactic_expr_opcode; }
std::string const & get_tactic_opcode() { return *g_tactic_opcode; }

class tactic_expr_macro_definition_cell : public macro_definition_cell {
public:
    tactic_expr_macro_definition_cell() {}
    virtual name get_name() const { return get_tactic_expr_name(); }
    virtual pair<expr, constraint_seq> check_type(expr const &, extension_context &, bool) const {
        return mk_pair(get_tactic_expr_type(), constraint_seq());
    }
    virtual optional<expr> expand(expr const &, extension_context &) const {
        return some_expr(get_tactic_expr_builtin());
    }
    virtual void write(serializer & s) const {
        s.write_string(get_tactic_expr_opcode());
    }
};

static macro_definition * g_tactic_expr_macro = nullptr;

expr mk_tactic_expr(expr const & e) {
    return mk_macro(*g_tactic_expr_macro, 1, &e, e.get_tag());
}

bool is_tactic_expr(expr const & e) {
    return is_macro(e) && macro_def(e).get_name() == get_tactic_expr_name();
}

expr const & get_tactic_expr_expr(expr const & e) {
    lean_assert(is_tactic_expr(e));
    expr const * it = &e;
    while (is_tactic_expr(*it))
        it = &macro_arg(*it, 0);
    return *it;
}

void check_tactic_expr(expr const & e, char const * error_msg) {
    if (!is_tactic_expr(e))
        throw expr_to_tactic_exception(e, error_msg);
}

name const & tactic_expr_to_id(expr e, char const * error_msg) {
    if (is_tactic_expr(e))
        e = get_tactic_expr_expr(e);

    if (is_constant(e)) {
        return const_name(e);
    } else if (is_local(e)) {
        return local_pp_name(e);
    } else if (is_as_atomic(e)) {
        e = get_app_fn(get_as_atomic_arg(e));
        if (is_explicit(e))
            e = get_explicit_arg(e);
        return tactic_expr_to_id(e, error_msg);
    } else {
        throw expr_to_tactic_exception(e, error_msg);
    }
}

static expr * g_expr_list_cons = nullptr;
static expr * g_expr_list_nil  = nullptr;

expr mk_expr_list(unsigned num, expr const * args) {
    expr r = *g_expr_list_nil;
    unsigned i = num;
    while (i > 0) {
        --i;
        r = mk_app(*g_expr_list_cons, args[i], r);
    }
    return r;
}

expr ids_to_tactic_expr(buffer<name> const & args) {
    buffer<expr> es;
    for (name const & id : args) {
        es.push_back(mk_local(id, mk_expr_placeholder()));
    }
    return mk_expr_list(es.size(), es.data());
}

void get_tactic_expr_list_elements(expr l, buffer<expr> & r, char const * error_msg) {
    while (true) {
        if (l == *g_expr_list_nil)
            return;
        if (!is_app(l) ||
            !is_app(app_fn(l)) ||
            app_fn(app_fn(l)) != *g_expr_list_cons ||
            !is_tactic_expr(app_arg(app_fn(l))))
            throw expr_to_tactic_exception(l, error_msg);
        r.push_back(get_tactic_expr_expr(app_arg(app_fn(l))));
        l = app_arg(l);
    }
}

void get_tactic_id_list_elements(expr l, buffer<name> & r, char const * error_msg) {
    buffer<expr> es;
    get_tactic_expr_list_elements(l, es, error_msg);
    for (unsigned i = 0; i < es.size(); i++) {
        r.push_back(tactic_expr_to_id(es[i], error_msg));
    }
}

static void throw_failed(expr const & e) {
    throw expr_to_tactic_exception(e, "failed to convert expression into tactic");
}

/** \brief Return true if v is the constant tactic.builtin or the constant function that returns tactic.builtin_tactic */
static bool is_builtin_tactic(expr const & v) {
    if (is_lambda(v))
        return is_builtin_tactic(binding_body(v));
    else if (v == *g_builtin_tac)
        return true;
    else
        return false;
}

tactic expr_to_tactic(type_checker & tc, elaborate_fn const & fn, expr e, pos_info_provider const * p) {
    e = copy_tag(e, tc.whnf(e).first);
    expr f = get_app_fn(e);
    if (!is_constant(f))
        throw_failed(e);
    optional<declaration> it = tc.env().find(const_name(f));
    if (!it || !it->is_definition())
        throw_failed(e);
    expr v = it->get_value();
    if (is_builtin_tactic(v)) {
        auto const & map = get_expr_to_tactic_map();
        auto it2 = map.find(const_name(f));
        if (it2 != map.end())
            return it2->second(tc, fn, e, p);
        else
            throw expr_to_tactic_exception(e, sstream() << "implementation for builtin tactic '" <<
                                           const_name(f) << "' was not found");
    } else {
        // unfold definition
        buffer<expr> locals;
        get_app_rev_args(e, locals);
        level_param_names const & ps = it->get_univ_params();
        levels ls = const_levels(f);
        unsigned num_ps = length(ps);
        unsigned num_ls = length(ls);
        if (num_ls > num_ps)
            throw expr_to_tactic_exception(e, sstream() << "invalid number of universes");
        if (num_ls < num_ps) {
            buffer<level> extra_ls;
            name_generator ngen = tc.mk_ngen();
            for (unsigned i = num_ls; i < num_ps; i++)
                extra_ls.push_back(mk_meta_univ(ngen.next()));
            ls = append(ls, to_list(extra_ls.begin(), extra_ls.end()));
        }
        v = instantiate_univ_params(v, ps, ls);
        v = apply_beta(v, locals.size(), locals.data());
        return expr_to_tactic(tc, fn, v, p);
    }
}

static name * g_tmp_prefix = nullptr;
LEAN_THREAD_VALUE(unsigned, g_expr_tac_id, 0);
static name_generator next_name_generator() {
    unsigned r = g_expr_tac_id;
    g_expr_tac_id++;
    return name_generator(name(*g_tmp_prefix, r));
}

unsigned get_unsigned(type_checker & tc, expr const & e, expr const & ref) {
    optional<mpz> k = to_num(e);
    if (!k)
        k = to_num(tc.whnf(e).first);
    if (!k)
        throw expr_to_tactic_exception(ref, "invalid tactic, second argument must be a numeral");
    if (!k->is_unsigned_int())
        throw expr_to_tactic_exception(ref,
                                       "invalid tactic, second argument does not fit in "
                                       "a machine unsigned integer");
    return k->get_unsigned_int();
}

unsigned get_unsigned_arg(type_checker & tc, expr const & e, unsigned i) {
    buffer<expr> args;
    get_app_args(e, args);
    if (i >= args.size())
        throw expr_to_tactic_exception(e, "invalid tactic, insufficient number of arguments");
    return get_unsigned(tc, args[i], e);
}

optional<unsigned> get_optional_unsigned(type_checker & tc, expr const & e) {
    if (is_app(e) && is_constant(get_app_fn(e))) {
        if (const_name(get_app_fn(e)) == get_option_some_name()) {
            return optional<unsigned>(get_unsigned(tc, app_arg(e), e));
        } else if (const_name(get_app_fn(e)) == get_option_none_name()) {
            return optional<unsigned>();
        }
    }
    throw expr_to_tactic_exception(e, "invalid tactic, argument is not an option num");
}

class tac_builtin_opaque_converter : public projection_converter {
public:
    tac_builtin_opaque_converter(environment const & env):projection_converter(env) {}
    virtual bool is_opaque(declaration const & d) const {
        name n = d.get_name();
        if (!is_prefix_of(get_tactic_name(), n))
            return projection_converter::is_opaque(d);
        expr v = d.get_value();
        while (is_lambda(v))
            v = binding_body(v);
        if (is_constant(v) && const_name(v) == get_tactic_builtin_name())
            return true;
        return projection_converter::is_opaque(d);
    }
};

tactic expr_to_tactic(environment const & env, elaborate_fn const & fn, expr const & e, pos_info_provider const * p) {
    bool memoize             = false;
    type_checker tc(env, next_name_generator(), std::unique_ptr<converter>(new tac_builtin_opaque_converter(env)), memoize);
    return expr_to_tactic(tc, fn, e, p);
}

tactic fixpoint(expr const & b, elaborate_fn const & fn) {
    return tactic([=](environment const & env, io_state const & ios, proof_state const & s) -> proof_state_seq {
            return expr_to_tactic(env, fn, b, nullptr)(env, ios, s);
        });
}

void register_simple_tac(name const & n, std::function<tactic()> f) {
    register_tac(n, [=](type_checker &, elaborate_fn const &, expr const & e, pos_info_provider const *) {
            if (!is_constant(e))
                throw expr_to_tactic_exception(e, "invalid constant tactic");
            return f();
        });
}

void register_bin_tac(name const & n, std::function<tactic(tactic const &, tactic const &)> f) {
    register_tac(n, [=](type_checker & tc, elaborate_fn const & fn, expr const & e, pos_info_provider const * p) {
            buffer<expr> args;
            get_app_args(e, args);
            if (args.size() != 2)
                throw expr_to_tactic_exception(e, "invalid binary tactic, it must have two arguments");
            tactic t1 = expr_to_tactic(tc, fn, args[0], p);
            tactic t2 = expr_to_tactic(tc, fn, args[1], p);
            return f(t1, t2);
        });
}

void register_unary_tac(name const & n, std::function<tactic(tactic const &)> f) {
    register_tac(n, [=](type_checker & tc, elaborate_fn const & fn, expr const & e, pos_info_provider const * p) {
            buffer<expr> args;
            get_app_args(e, args);
            if (args.size() != 1)
                throw expr_to_tactic_exception(e, "invalid unary tactic, it must have one argument");
            return f(expr_to_tactic(tc, fn, args[0], p));
        });
}

void register_unary_num_tac(name const & n, std::function<tactic(tactic const &, unsigned k)> f) {
    register_tac(n, [=](type_checker & tc, elaborate_fn const & fn, expr const & e, pos_info_provider const * p) {
            buffer<expr> args;
            get_app_args(e, args);
            if (args.size() != 2)
                throw expr_to_tactic_exception(e, "invalid tactic, it must have two arguments");
            tactic t = expr_to_tactic(tc, fn, args[0], p);
            return f(t, get_unsigned_arg(tc, e, 1));
        });
}

void register_num_tac(name const & n, std::function<tactic(unsigned k)> f) {
    register_tac(n, [=](type_checker & tc, elaborate_fn const &, expr const & e, pos_info_provider const *) {
            buffer<expr> args;
            get_app_args(e, args);
            if (args.size() != 1)
                throw expr_to_tactic_exception(e, "invalid tactic, it must have one argument");
            return f(get_unsigned_arg(tc, e, 0));
        });
}

static name * g_by_name = nullptr;
static name * g_by_plus_name = nullptr;

expr mk_by(expr const & e) { return mk_annotation(*g_by_name, e); }
bool is_by(expr const & e) { return is_annotation(e, *g_by_name); }
expr const & get_by_arg(expr const & e) { lean_assert(is_by(e)); return get_annotation_arg(e); }

expr mk_by_plus(expr const & e) { return mk_annotation(*g_by_plus_name, e); }
bool is_by_plus(expr const & e) { return is_annotation(e, *g_by_plus_name); }
expr const & get_by_plus_arg(expr const & e) { lean_assert(is_by_plus(e)); return get_annotation_arg(e); }

void initialize_expr_to_tactic() {
    g_tmp_prefix        = new name(name::mk_internal_unique_name());

    g_by_name           = new name("by");
    register_annotation(*g_by_name);

    g_by_plus_name      = new name("by+");
    register_annotation(*g_by_plus_name);

    g_map               = new expr_to_tactic_map();

    g_tactic_expr_type       = new expr(mk_constant(get_tactic_expr_name()));
    g_tactic_expr_builtin    = new expr(mk_constant(get_tactic_expr_builtin_name()));
    g_tactic_expr_list_type  = new expr(mk_constant(get_tactic_expr_list_name()));
    g_tactic_identifier_type = new expr(mk_constant(get_tactic_identifier_name()));
    g_tactic_using_expr_type = new expr(mk_constant(get_tactic_using_expr_name()));
    g_tactic_expr_opcode     = new std::string("TACE");
    g_tactic_expr_macro      = new macro_definition(new tactic_expr_macro_definition_cell());

    register_macro_deserializer(*g_tactic_expr_opcode,
                                [](deserializer &, unsigned num, expr const * args) {
                                    if (num != 1)
                                        throw corrupted_stream_exception();
                                    return mk_tactic_expr(args[0]);
                                });

    g_expr_list_cons = new expr(mk_constant(get_tactic_expr_list_cons_name()));
    g_expr_list_nil  = new expr(mk_constant(get_tactic_expr_list_nil_name()));

    g_and_then_tac_fn   = new expr(Const(get_tactic_and_then_name()));
    g_or_else_tac_fn    = new expr(Const(get_tactic_or_else_name()));
    g_id_tac_fn         = new expr(Const(get_tactic_id_name()));
    g_repeat_tac_fn     = new expr(Const(get_tactic_repeat_name()));
    g_determ_tac_fn     = new expr(Const(get_tactic_determ_name()));
    g_tac_type          = new expr(Const(get_tactic_name()));
    g_builtin_tac       = new expr(Const(get_tactic_builtin_name()));
    g_fixpoint_tac      = new expr(Const(get_tactic_fixpoint_name()));

    register_simple_tac(get_tactic_id_name(),
                        []() { return id_tactic(); });
    register_simple_tac(get_tactic_now_name(),
                        []() { return now_tactic(); });
    register_simple_tac(get_tactic_fail_name(),
                        []() { return fail_tactic(); });
    register_simple_tac(get_tactic_beta_name(),
                        []() { return beta_tactic(); });
    register_bin_tac(get_tactic_and_then_name(),
                     [](tactic const & t1, tactic const & t2) { return then(t1, t2); });
    register_bin_tac(get_tactic_append_name(),
                     [](tactic const & t1, tactic const & t2) { return append(t1, t2); });
    register_bin_tac(get_tactic_interleave_name(),
                     [](tactic const & t1, tactic const & t2) { return interleave(t1, t2); });
    register_bin_tac(get_tactic_par_name(),
                     [](tactic const & t1, tactic const & t2) { return par(t1, t2); });
    register_bin_tac(get_tactic_or_else_name(),
                     [](tactic const & t1, tactic const & t2) { return orelse(t1, t2); });
    register_unary_tac(get_tactic_repeat_name(),
                       [](tactic const & t1) { return repeat(t1); });
    register_unary_tac(get_tactic_all_goals_name(),
                       [](tactic const & t1) { return all_goals(t1); });
    register_unary_num_tac(get_tactic_at_most_name(),
                           [](tactic const & t, unsigned k) { return take(t, k); });
    register_unary_num_tac(get_tactic_discard_name(),
                           [](tactic const & t, unsigned k) { return discard(t, k); });
    register_unary_num_tac(get_tactic_focus_at_name(),
                           [](tactic const & t, unsigned k) { return focus(t, k); });
    register_unary_num_tac(get_tactic_try_for_name(),
                           [](tactic const & t, unsigned k) { return try_for(t, k); });
    register_num_tac(get_tactic_rotate_left_name(), [](unsigned k) { return rotate_left(k); });
    register_num_tac(get_tactic_rotate_right_name(), [](unsigned k) { return rotate_right(k); });

    register_tac(get_tactic_fixpoint_name(),
                 [](type_checker & tc, elaborate_fn const & fn, expr const & e, pos_info_provider const *) {
                     if (!is_constant(app_fn(e)))
                         throw expr_to_tactic_exception(e, "invalid fixpoint tactic, it must have one argument");
                     expr r = tc.whnf(mk_app(app_arg(e), e)).first;
                     return fixpoint(r, fn);
                 });
}

void finalize_expr_to_tactic() {
    delete g_expr_list_cons;
    delete g_expr_list_nil;
    delete g_tactic_expr_type;
    delete g_tactic_expr_builtin;
    delete g_tactic_expr_list_type;
    delete g_tactic_identifier_type;
    delete g_tactic_using_expr_type;
    delete g_tactic_expr_opcode;
    delete g_tactic_expr_macro;
    delete g_fixpoint_tac;
    delete g_builtin_tac;
    delete g_tac_type;
    delete g_determ_tac_fn;
    delete g_repeat_tac_fn;
    delete g_or_else_tac_fn;
    delete g_and_then_tac_fn;
    delete g_id_tac_fn;
    delete g_map;
    delete g_tactic_opcode;
    delete g_by_name;
    delete g_by_plus_name;
    delete g_tmp_prefix;
}
}