/*
Copyright (c) 2013 Microsoft Corporation. All rights reserved.
Released under Apache 2.0 license as described in the file LICENSE.

Author: Leonardo de Moura
*/
#include <cstring>
#include <vector>
#include <algorithm>
#include "name.h"
#include "debug.h"
#include "rc.h"
#include "hash.h"
#include "trace.h"

namespace lean {

constexpr char const * anonymous_str = "[anonymous]";

struct name::imp {
    MK_LEAN_RC()
    bool     m_is_string;
    imp *    m_prefix;
    union {
        char * m_str;
        unsigned m_k;
    };

    void dealloc() {
        imp * curr = this;
        while (true) {
            lean_assert(curr->get_rc() == 0);
            imp * p = curr->m_prefix;
            if (curr->m_is_string)
                delete[] reinterpret_cast<char*>(curr);
            else
                delete curr;
            curr = p;
            if (!curr || !curr->dec_ref_core())
                break;
        }
    }

    imp(bool s, imp * p):m_rc(1), m_is_string(s), m_prefix(p) { if (p) p->inc_ref(); }

    static void display_core(std::ostream & out, char const * sep, imp * p) {
        lean_assert(p != nullptr);
        if (p->m_prefix) {
            display_core(out, sep, p->m_prefix);
            out << sep;
        }
        if (p->m_is_string)
            out << p->m_str;
        else
            out << p->m_k;
    }

    static void display(std::ostream & out, char const * sep, imp * p) {
        if (p == nullptr)
            out << anonymous_str;
        else
            display_core(out, sep, p);
    }

    friend void copy_limbs(imp * p, std::vector<name::imp *> & limbs) {
        limbs.clear();
        while (p != nullptr) {
            limbs.push_back(p);
            p = p->m_prefix;
        }
        std::reverse(limbs.begin(), limbs.end());
    }
};

name::name(imp * p) {
    m_imp = p;
    if (m_imp)
        m_imp->inc_ref();
}

name::name() {
    m_imp = nullptr;
}

name::name(name const & prefix, char const * name) {
    size_t sz  = strlen(name);
    lean_assert(sz < 1u<<31);
    char * mem = new char[sizeof(imp) + sz + 1];
    m_imp      = new (mem) imp(true, prefix.m_imp);
    memcpy(mem + sizeof(imp), name, sz + 1);
    m_imp->m_str       = mem + sizeof(imp);
}

name::name(name const & prefix, unsigned k) {
    m_imp      = new imp(false, prefix.m_imp);
    m_imp->m_k = k;
}

name::name(char const * n):name(name(), n) {
}

name::name(unsigned k):name(name(), k) {
}

name::name(name const & other):m_imp(other.m_imp) {
    m_imp->inc_ref();
}

name::name(name && other):m_imp(other.m_imp) {
    other.m_imp = 0;
}

name::~name() {
    if (m_imp)
        m_imp->dec_ref();
}

name & name::operator=(name const & other) {
    if (other.m_imp)
        other.m_imp->inc_ref();
    if (m_imp)
        m_imp->dec_ref();
    m_imp = other.m_imp;
    return *this;
}

name & name::operator=(name && other) {
    lean_assert(this != &other);
    if (m_imp)
        m_imp->dec_ref();
    m_imp       = other.m_imp;
    other.m_imp = 0;
    return *this;
}

name_kind name::kind() const {
    if (m_imp == nullptr)
        return name_kind::ANONYMOUS;
    else
        return m_imp->m_is_string ? name_kind::STRING : name_kind::NUMERAL;
}

unsigned name::get_numeral() const {
    lean_assert(is_numeral());
    return m_imp->m_k;
}

char const * name::get_string() const {
    lean_assert(is_string());
    return m_imp->m_str;
}

bool operator==(name const & a, name const & b) {
    name::imp * i1 = a.m_imp;
    name::imp * i2 = b.m_imp;
    while (true) {
        if (i1 == i2)
            return true;
        if ((i1 == nullptr) != (i2 == nullptr))
            return false;
        lean_assert(i1 != nullptr);
        lean_assert(i2 != nullptr);
        if (i1->m_is_string != i2->m_is_string)
            return false;
        if (i1->m_is_string) {
            if (strcmp(i1->m_str, i2->m_str) != 0)
                return false;
        }
        else {
            if (i1->m_k != i2->m_k)
                return false;
        }
        i1 = i1->m_prefix;
        i2 = i2->m_prefix;
    }
}

int cmp(name::imp * i1, name::imp * i2) {
    static thread_local std::vector<name::imp *> limbs1;
    static thread_local std::vector<name::imp *> limbs2;
    copy_limbs(i1, limbs1);
    copy_limbs(i2, limbs2);
    auto it1 = limbs1.begin();
    auto it2 = limbs2.begin();
    for (; it1 != limbs1.end() && it2 != limbs2.end(); ++it1, ++it2) {
        i1 = *it1;
        i2 = *it2;

        if (i1->m_is_string != i2->m_is_string)
            return i1->m_is_string ? 1 : -1;

        if (i1->m_is_string) {
            int c = strcmp(i1->m_str, i2->m_str);
            if (c != 0)
                return c;
        }
        else if (i1->m_k != i2->m_k) {
            return i1->m_k < i2->m_k ? -1 : 1;
        }
    }
    if (it1 == limbs1.end() && it2 == limbs2.end())
        return 0;
    else return it1 == limbs1.end() ? -1 : 1;
}

bool name::is_atomic() const {
    return m_imp == nullptr || m_imp->m_prefix == nullptr;
}

name name::get_prefix() const {
    lean_assert(!is_atomic());
    return name(m_imp->m_prefix);
}

static unsigned num_digits(unsigned k) {
    if (k == 0)
        return 1;
    int r = 0;
    while (k != 0) {
        k /= 10;
        r++;
    }
    return r;
}

size_t name::size(char const * sep) const {
    if (m_imp == nullptr) {
        return strlen(anonymous_str);
    }
    else {
        imp * i       = m_imp;
        size_t sep_sz = strlen(sep);
        size_t r      = 0;
        while (true) {
            if (i->m_is_string) {
                r += strlen(i->m_str);
            }
            else {
                r += num_digits(i->m_k);
            }
            if (i->m_prefix) {
                r += sep_sz;
                i  = i->m_prefix;
            }
            else {
                break;
            }
        }
        return r;
    }
}

unsigned name::hash() const {
    if (m_imp == nullptr)
        return 17;
    else {
        unsigned h = 13;
        imp const * i = m_imp;
        do {
            if (i->m_is_string)
                h = ::lean::hash(i->m_str, strlen(i->m_str), h);
            else
                h = ::lean::hash(h, i->m_k);
            i = i->m_prefix;
        }
        while (i != nullptr);
        return h;
    }
}

std::ostream & operator<<(std::ostream & out, name const & n) {
    name::imp::display(out, default_name_separator, n.m_imp);
    return out;
}

name::sep::sep(name const & n, char const * s):m_name(n), m_sep(s) {}

std::ostream & operator<<(std::ostream & out, name::sep const & s) {
    name::imp::display(out, s.m_sep, s.m_name.m_imp);
    return out;
}

}