/*
Copyright (c) 2016 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.

Author: Leonardo de Moura
*/
#include <algorithm>
#include "kernel/instantiate.h"
#include "kernel/abstract.h"
#include "kernel/for_each_fn.h"
#include "library/locals.h"
#include "library/placeholder.h"
#include "library/tactic/elaborate.h"
#include "frontends/lean/decl_util.h"
#include "frontends/lean/tokens.h"
#include "frontends/lean/parser.h"
#include "frontends/lean/elaborator.h"

namespace lean {
bool parse_univ_params(parser & p, buffer<name> & lp_names) {
    if (p.curr_is_token(get_llevel_curly_tk())) {
        p.next();
        while (!p.curr_is_token(get_rcurly_tk())) {
            name l = p.check_id_next("invalid universe parameter, identifier expected");
            p.add_local_level(l, mk_param_univ(l));
            lp_names.push_back(l);
        }
        p.next();
        return true;
    } else{
        return false;
    }
}

expr parse_single_header(parser & p, buffer<name> & lp_names, buffer<expr> & params) {
    auto c_pos  = p.pos();
    name c_name = p.check_id_next("invalid declaration, identifier expected");
    parse_univ_params(p, lp_names);
    p.parse_optional_binders(params);
    for (expr const & param : params)
        p.add_local(param);
    expr type;
    if (p.curr_is_token(get_colon_tk())) {
        p.next();
        type = p.parse_expr();
    } else {
        type = p.save_pos(mk_expr_placeholder(), c_pos);
    }
    expr c   = p.save_pos(mk_local(c_name, type), c_pos);
    return c;
}

void parse_mutual_header(parser & p, buffer<name> & lp_names, buffer<expr> & cs, buffer<expr> & params) {
    if (p.curr_is_token(get_lcurly_tk())) {
        p.next();
        while (!p.curr_is_token(get_rcurly_tk())) {
            name l = p.check_atomic_id_next("invalid mutual declaration, identifier expected");
            lp_names.push_back(l);
            p.add_local_level(l, mk_param_univ(l));
        }
        p.next();
    }
    while (true) {
        auto c_pos  = p.pos();
        name c_name = p.check_id_next("invalid mutual declaration, identifier expected");
        cs.push_back(p.save_pos(mk_local(c_name, mk_expr_placeholder()), c_pos));
        if (!p.curr_is_token(get_comma_tk()))
            break;
        p.next();
    }
    p.parse_optional_binders(params);
    for (expr const & param : params)
        p.add_local(param);
    for (expr const & c : cs)
        p.add_local(c);
}

expr parse_inner_header(parser & p, name const & c_expected) {
    p.check_token_next(get_with_tk(), "invalid mutual declaration, 'with' expected");
    auto id_pos = p.pos();
    name n = p.check_id_next("invalid mutual declaration, identifier expected");
    if (c_expected != n)
        throw parser_error(sstream() << "invalid mutual declaration, '" << c_expected << "' expected",
                           id_pos);
    p.check_token_next(get_colon_tk(), "invalid mutual declaration, ':' expected");
    return p.parse_expr();
}

/** \brief Version of collect_locals(expr const & e, collected_locals & ls) that ignores local constants occurring in
    tactics. */
void collect_locals_ignoring_tactics(expr const & e, collected_locals & ls) {
    if (!has_local(e)) return;
    for_each(e, [&](expr const & e, unsigned) {
            if (!has_local(e)) return false;
            if (is_by(e))      return false; // do not visit children
            if (is_local(e))   ls.insert(e);
            return true;
        });
}

name_set collect_univ_params_ignoring_tactics(expr const & e, name_set const & ls) {
    if (!has_param_univ(e)) return ls;
    name_set r = ls;
    for_each(e, [&](expr const & e, unsigned) {
            if (!has_param_univ(e)) {
                return false;
            } else if (is_by(e)) {
                return false;
            } else if (is_sort(e)) {
                collect_univ_params_core(sort_level(e), r);
            } else if (is_constant(e)) {
                for (auto const & l : const_levels(e))
                    collect_univ_params_core(l, r);
            }
            return true;
        });
    return r;
}

/** \brief Collect annonymous instances in section/namespace declarations such as:

        variable [decidable_eq A]
*/
void collect_annonymous_inst_implicit(parser const & p, collected_locals & locals) {
    buffer<pair<name, expr>> entries;
    to_buffer(p.get_local_entries(), entries);
    unsigned i = entries.size();
    while (i > 0) {
        --i;
        auto const & entry = entries[i];
        if (is_local(entry.second) && !locals.contains(entry.second) && local_info(entry.second).is_inst_implicit() &&
            // remark: remove the following condition condition, if we want to auto inclusion also for non anonymous ones.
            p.is_anonymous_inst_name(entry.first)) {
            bool ok = true;
            for_each(mlocal_type(entry.second), [&](expr const & e, unsigned) {
                    if (!ok) return false; // stop
                    if (is_local(e) && !locals.contains(e))
                        ok = false;
                    return true;
                });
            if (ok)
                locals.insert(entry.second);
        }
    }
}

/** \brief Sort local names by order of occurrence, and copy the associated parameters to ps */
void sort_locals(buffer<expr> const & locals, parser const & p, buffer<expr> & ps) {
    buffer<expr> extra;
    name_set     explicit_param_names;
    for (expr const & p : ps) {
        explicit_param_names.insert(mlocal_name(p));
    }
    for (expr const & l : locals) {
        // we only copy the locals that are in p's local context
        if (p.is_local_decl(l) && !explicit_param_names.contains(mlocal_name(l)))
            extra.push_back(l);
    }
    std::sort(extra.begin(), extra.end(), [&](expr const & p1, expr const & p2) {
            bool is_var1 = p.is_local_variable(p1);
            bool is_var2 = p.is_local_variable(p2);
            if (!is_var1 && is_var2)
                return true;
            else if (is_var1 && !is_var2)
                return false;
            else
                return p.get_local_index(p1) < p.get_local_index(p2);
        });
    buffer<expr> new_ps;
    new_ps.append(extra);
    new_ps.append(ps);
    ps.clear();
    ps.append(new_ps);
}

/** TODO(Leo): mark as static */
void update_univ_parameters(parser & p, buffer<name> & lp_names, name_set const & found) {
    unsigned old_sz = lp_names.size();
    found.for_each([&](name const & n) {
            if (std::find(lp_names.begin(), lp_names.begin() + old_sz, n) == lp_names.begin() + old_sz)
                lp_names.push_back(n);
        });
    std::sort(lp_names.begin(), lp_names.end(), [&](name const & n1, name const & n2) {
            return p.get_local_level_index(n1) < p.get_local_level_index(n2);
        });
}

void collect_implicit_locals(parser & p, buffer<name> & lp_names, buffer<expr> & params, buffer<expr> const & all_exprs) {
    collected_locals locals;
    buffer<expr> include_vars;
    name_set lp_found;
    /** Process variables included using the 'include' command */
    p.get_include_variables(include_vars);
    for (expr const & param : include_vars) {
        if (is_local(param)) {
            collect_locals_ignoring_tactics(mlocal_type(param), locals);
            lp_found = collect_univ_params_ignoring_tactics(mlocal_type(param), lp_found);
            locals.insert(param);
        }
    }
    /** Process explicit parameters */
    for (expr const & param : params) {
        collect_locals_ignoring_tactics(mlocal_type(param), locals);
        lp_found = collect_univ_params_ignoring_tactics(mlocal_type(param), lp_found);
        locals.insert(param);
    }
    /** Process expressions used to define declaration. */
    for (expr const & e : all_exprs) {
        collect_locals_ignoring_tactics(e, locals);
        lp_found = collect_univ_params_ignoring_tactics(e, lp_found);
    }
    collect_annonymous_inst_implicit(p, locals);
    sort_locals(locals.get_collected(), p, params);
    update_univ_parameters(p, lp_names, lp_found);
}

void collect_implicit_locals(parser & p, buffer<name> & lp_names, buffer<expr> & params, expr const & e) {
    buffer<expr> all_exprs; all_exprs.push_back(e);
    collect_implicit_locals(p, lp_names, params, all_exprs);
}

void elaborate_params(elaborator & elab, buffer<expr> const & params, buffer<expr> & new_params) {
    for (unsigned i = 0; i < params.size(); i++) {
        expr const & param = params[i];
        expr type          = replace_locals(mlocal_type(param), i, params.data(), new_params.data());
        expr new_type      = elab.elaborate_type(type);
        expr new_param     = elab.push_local(local_pp_name(param), new_type, local_info(param));
        new_params.push_back(new_param);
    }
}
}