/*
 * This file is part of libgim.
 *
 * libgim is free software: you can redistribute it and/or modify it under the
 * terms of the GNU General Public License as published by the Free Software
 * Foundation, either version 3 of the License, or (at your option) any later
 * version.
 *
 * libgim is distributed in the hope that it will be useful, but WITHOUT ANY
 * WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
 * FOR A PARTICULAR PURPOSE.  See the GNU General Public License for more
 * details.
 *
 * You should have received a copy of the GNU General Public License
 * along with libgim.  If not, see <http://www.gnu.org/licenses/>.
 *
 * Copyright 2010-2015 Danny Robson <danny@nerdcruft.net>
 */


#include "json.hpp"

#include "debug.hpp"
#include "io.hpp"
#include "maths.hpp"

#include <algorithm>
#include <cstdlib>
#include <deque>
#include <iomanip>
#include <sstream>
#include <stdexcept>

#include <fcntl.h>
#include <string.h>
#include <sys/stat.h>
#include <sys/types.h>


using namespace std;
using namespace util;

//-----------------------------------------------------------------------------
%%{
    # JSON (rfc7159)
    machine json;

    action trace { if (false) std::cerr << *p; }
    action success { __success = true; }
    action failure { }

    action new_line { ++line; }

    action first { parsed.push_back ({ type::UNKNOWN, p, p}); }
    action last  { parsed.back ().last  = p; }

    action tag_nul     { parsed.back ().tag = type::NUL; }
    action tag_boolean { parsed.back ().tag = type::BOOLEAN; }
    action tag_string  { parsed.back ().tag = type::STRING; }
    action tag_integer { parsed.back ().tag = type::INTEGER; }
    action tag_real    { parsed.back ().tag = type::REAL; }

    action tag_object_begin { parsed.push_back ({ type::OBJECT_BEGIN,   p, p + 1 }); }
    action tag_object_end   { parsed.push_back ({ type::OBJECT_END,     p, p + 1 }); }
    action tag_array_begin  { parsed.push_back ({ type::ARRAY_BEGIN,    p, p + 1 }); }
    action tag_array_end    { parsed.push_back ({ type::ARRAY_END,      p, p + 1 }); }

    # Line counter
    lines = (
          any | '\n' @new_line
    )*;

    # UTF-8 (rfc3629)
    utf8_tail = 0x80..0xbf;

    utf8_1 =      0x00..0x7f;
    utf8_2 =      0xc2..0xdf utf8_tail;
    utf8_3 = 0xe0 0xa0..0xbf utf8_tail      |
                  0xe1..0xec utf8_tail{2}   |
             0xed 0x80..0x9f utf8_tail      |
                  0xee..0xef utf8_tail{2};
    utf8_4 = 0xf0 0x90..0xbf utf8_tail{2}   |
                  0xf1..0xf3 utf8_tail{3}   |
             0xf4 0x80..0x8f utf8_tail{2};


    utf8 = utf8_1 | utf8_2 | utf8_3 | utf8_4;

    # Utility
    ws = 0x20 | 0x09 | 0x0A | 0x0D;
    array_start  = '[';
    array_end    = ']';
    object_start = '{';
    object_end   = '}';

    # Strings
    char =
          (utf8 - ["\\])
        | "\\" (
              [\\"/bfnrt]
            | "u" xdigit{4}
        )
    ;

    string = ('"' char* '"') >first >tag_string %*last;

    # numbers
    int = '0' | [1-9] digit*;

    frac = '.' digit+;
    e    = 'e'i[+\-]?;
    exp  = e digit+;

    number = (
        '-'?
        int
        (frac >tag_real)?
        exp?
    ) >tag_integer;

    # wrapper types
    array  = array_start  @{ fhold; fcall array_members;  } array_end;
    object = object_start @{ fhold; fcall object_members; } object_end;

    # simple types; case sensitive literals
    bool = ("true" | "false") >tag_boolean;
    nul  = "null" >tag_nul;
    literal = bool | nul;

    value = object | array | (number | string | literal) >first %last;

    # Complex
    member  = string ws* ':' ws* value;

    array_members  := ((
        array_start >tag_array_begin ws* (value  ws* (',' ws* value  ws*)*)? array_end >tag_array_end
    ) & lines)
    @{ fhold; fret; } $trace $!failure;

    object_members := ((
        object_start >tag_object_begin ws* (member ws* (',' ws* member ws*)*)? object_end >tag_object_end
    ) & lines)
    @{ fhold; fret; } $trace $!failure;

    # meta types
    document := ((ws* value ws*) & lines)
    %success
    $!failure
    $trace;

    variable stack ragelstack;
    prepush { ragelstack.push_back (0); }
    postpop { ragelstack.pop_back (); }

    write data;
}%%


std::ostream& operator<< (std::ostream &os, json::flat::type);


//-----------------------------------------------------------------------------
std::vector<json::flat::item>
json::flat::parse (const char *first, const char *last)
{
    const char *p   = first;
    const char *pe  = last;
    const char *eof = pe;

    std::deque<int> ragelstack;
    std::vector<item> parsed;

    size_t line = 0;
    int cs, top;
    bool __success = false;

    %%write init;
    %%write exec;

    if (!__success)
        throw parse_error (line, "parse error");

    return parsed;
}


std::vector<json::flat::item>
json::flat::parse (const boost::filesystem::path &path)
{
    util::mapped_file f (path);
    return parse ((const char *)f.cbegin (), (const char*)f.cend ());
}


//-----------------------------------------------------------------------------
// External support

template <>
bool
is_integer (const json::tree::number &node)
{
    return is_integer (node.native ());
}


template <>
bool
is_integer (const json::tree::node &node)
{
    return node.is_number () &&
           is_integer (node.as_number ());
}


//-----------------------------------------------------------------------------
// Node
static std::vector<json::flat::item>::const_iterator
parse (std::vector<json::flat::item>::const_iterator first,
       std::vector<json::flat::item>::const_iterator last,
       std::unique_ptr<json::tree::node> &output);


//-----------------------------------------------------------------------------
static std::vector<json::flat::item>::const_iterator
parse (std::vector<json::flat::item>::const_iterator first,
       std::vector<json::flat::item>::const_iterator last,
       json::tree::array &parent)
{
    for (auto cursor = first; cursor != last; ) {
        if (cursor->tag == json::flat::type::ARRAY_END)
            return cursor + 1;

        std::unique_ptr<json::tree::node> value;
        cursor = ::parse (cursor, last, value);
        parent.insert (std::move (value));
    }

    unreachable ();
}


//-----------------------------------------------------------------------------
static std::vector<json::flat::item>::const_iterator
parse (std::vector<json::flat::item>::const_iterator first,
       std::vector<json::flat::item>::const_iterator last,
       json::tree::object &parent)
{
    for (auto cursor = first; cursor != last; ) {
        if (cursor->tag == json::flat::type::OBJECT_END)
            return cursor + 1;

        CHECK_EQ (cursor->tag, json::flat::type::STRING);

        std::string key (cursor->first + 1, cursor->last - 1);
        ++cursor;

        std::unique_ptr<json::tree::node> val;
        cursor = ::parse (cursor, last, val);

        parent.insert (key, std::move (val));
    }

    unreachable ();
}


//-----------------------------------------------------------------------------
static std::vector<json::flat::item>::const_iterator
parse (std::vector<json::flat::item>::const_iterator first,
       std::vector<json::flat::item>::const_iterator last,
       std::unique_ptr<json::tree::node> &output)
{
    CHECK (first != last);
    CHECK (output.get () == nullptr);

    switch (first->tag) {
        case json::flat::type::NUL:
            output.reset (new json::tree::null ());
            return first + 1;

        case json::flat::type::BOOLEAN:
            CHECK (*first->first == 't' || *first->first == 'f');
            output.reset (new json::tree::boolean (*first->first == 't'));
            return first + 1;

        case json::flat::type::STRING:
            CHECK_NEQ (first->first, first->last);
            output.reset (new json::tree::string (first->first + 1, first->last - 1));
            return first + 1;

        case json::flat::type::INTEGER:
        case json::flat::type::REAL:
            output.reset (new json::tree::number (std::atof (first->first)));
            return first + 1;

        case json::flat::type::ARRAY_BEGIN: {
            auto value = std::make_unique<json::tree::array> ();
            auto cursor = ::parse (first + 1, last, *value);
            output = std::move (value);
            return cursor;
        }

        case json::flat::type::OBJECT_BEGIN: {
            auto value = std::make_unique<json::tree::object> ();
            auto cursor = ::parse (first + 1, last, *value);
            output = std::move (value);
            return cursor;
        }

        default:
            unreachable ();
    }
}

//-----------------------------------------------------------------------------
std::unique_ptr<json::tree::node>
json::tree::parse (const boost::filesystem::path &path)
{
    util::mapped_file f (path);
    return parse ((const char*)f.cbegin (), (const char*)f.cend ());
}


std::unique_ptr<json::tree::node>
json::tree::parse (const std::string &path)
    { return parse (path.c_str (), path.c_str () + path.size ()); }


std::unique_ptr<json::tree::node>
json::tree::parse (const char *start)
    { return parse (start, start + strlen (start)); }


void
json::tree::write (const json::tree::node &node, std::ostream &os)
    { node.write (os); }


std::unique_ptr<json::tree::node>
json::tree::parse (const char *first, const char *last)
{
    std::unique_ptr<json::tree::node> output;
    auto data = json::flat::parse (first, last);
    auto end  = ::parse (data.cbegin (), data.cend (), output);

    CHECK (end == data.cend ());
    (void)end;

    return output;
}


//-----------------------------------------------------------------------------
// Type conversion

const json::tree::object&
json::tree::node::as_object  (void) const
        { throw type_error ("node is not an object"); }


const json::tree::array&
json::tree::node::as_array   (void) const
        { throw type_error ("node is not an array"); }


const json::tree::string&
json::tree::node::as_string  (void) const
        { throw type_error ("node is not a string"); }


const json::tree::number&
json::tree::node::as_number  (void) const
        { throw type_error ("node is not a number"); }


const json::tree::boolean&
json::tree::node::as_boolean (void) const
        { throw type_error ("node is not a boolean"); }


const json::tree::null&
json::tree::node::as_null (void) const
        { throw type_error ("node is not a null"); }


//-----------------------------------------------------------------------------
// Global operatoers

bool
json::tree::node::operator!= (const node &rhs) const
    { return !(*this == rhs); }


bool json::tree::node::operator==(const char *rhs) const {
    try {
        return as_string ().native () == rhs;
    } catch (const json::tree::type_error&) {
        return false;
    }
}


const json::tree::node&
json::tree::node::operator[] (const std::string &key) const
    { return as_object ()[key]; }


const json::tree::node&
json::tree::node::operator[] (unsigned int idx) const
    { return as_array()[idx]; }


//-----------------------------------------------------------------------------
// Object

json::tree::object::~object ()
    { ; }


bool
json::tree::object::operator ==(const json::tree::object &rhs) const {
    for (auto i = rhs.m_values.begin (), j = m_values.begin ();
         i != rhs.m_values.end () && j != m_values.end ();
         ++i, ++j)
    {
        if (i->first != j->first)
            return false;
        if ((*i->second) != (*j->second))
            return false;
    }

    return true;
}


void
json::tree::object::insert (const std::string &_key, unique_ptr<json::tree::node> &&value)
        { m_values[_key] = move(value); }


const json::tree::node&
json::tree::object::operator[](const std::string &key) const {
    auto value = m_values.find (key);
    if (value == m_values.end ()) {
        ostringstream ss;
        ss << "no key: " << key;
        throw json::tree::error (ss.str());
    }

    return *value->second;
}


bool
json::tree::object::has (const std::string &key) const {
    return m_values.find (key) != m_values.end ();
}


void
json::tree::object::clear (void)
    { m_values.clear (); }


void
json::tree::object::erase (const std::string &key) {
    auto pos = m_values.find (key);
    if (pos == m_values.end ())
        throw json::tree::error ("erasing invalid key");

    m_values.erase (key);
}


json::tree::object::const_iterator
json::tree::object::begin (void) const
    { return m_values.begin (); }


json::tree::object::const_iterator
json::tree::object::end (void) const
    { return m_values.end (); }


std::ostream&
json::tree::object::write (std::ostream &os) const {
    os << "{\n";
    {
        indenter raii(os);

        for (auto i = m_values.begin (); i != m_values.end ();) {
            os << '"' << i->first << "\" : " << *i->second;

            if (++i != m_values.end ())
                os << ",\n";
        }
    }

    os << "\n}";
    return os;
}


//-----------------------------------------------------------------------------
// Array

json::tree::array::~array()
{
    m_values.clear ();
}


void
json::tree::array::insert (unique_ptr<json::tree::node> &&_value)
{
    m_values.push_back (move (_value));
}


bool
json::tree::array::operator ==(const json::tree::array &rhs) const {
    for (auto i = rhs.m_values.begin (), j = m_values.begin ();
         i != rhs.m_values.end () && j != m_values.end ();
         ++i, ++j)
    { if ((**i) != (**j)) return false; }

    return true;
}


std::ostream&
json::tree::array::write (std::ostream &os) const {
    os << "[\n";
    {
        indenter raii(os);

        for (auto i = m_values.begin (); i != m_values.end (); ++i) {
            (*i)->write (os);

            if (i != m_values.end () - 1)
                os << ",\n";
        }
    }
    os << "\n]";
    return os;
}


//-----------------------------------------------------------------------------
// String

std::ostream&
json::tree::string::write (std::ostream &os) const {
    os << '"' << m_value << '"';
    return os;
}


bool
json::tree::string::operator ==(const json::tree::string &rhs) const
    { return rhs.m_value == m_value; }


bool
json::tree::string::operator ==(const char *rhs) const
    { return rhs == m_value; }


//-----------------------------------------------------------------------------
// Number

std::ostream&
json::tree::number::write (std::ostream &os) const {
    os << setprecision (numeric_limits<double>::digits10) << m_value;
    return os;
}


bool
json::tree::number::operator ==(const json::tree::number &rhs) const
    { return almost_equal (rhs.m_value, m_value); }


//-----------------------------------------------------------------------------
// Boolean

std::ostream&
json::tree::boolean::write (std::ostream &os) const {
    os << (m_value ? "true" : "false");
    return os;
}

bool
json::tree::boolean::operator ==(const json::tree::boolean &rhs) const
    { return rhs.m_value == m_value; }


//-----------------------------------------------------------------------------
// Null

std::ostream&
json::tree::null::write (std::ostream &os) const {
    os << "null";
    return os;
}

ostream&
json::tree::operator <<(ostream &os, const json::tree::node &n)
    { return n.write (os); }


//-----------------------------------------------------------------------------
// to_json

namespace json { namespace tree {
    template <>
    std::unique_ptr<node>
    io<bool>::serialise (const bool &b) {
        return std::unique_ptr<node> (new boolean (b));
    }

    template <>
    std::unique_ptr<node>
    io<nullptr_t>::serialise (const nullptr_t &) {
        return std::unique_ptr<node> (new null ());
    }

    template <>
    std::unique_ptr<node>
    io<std::string>::serialise (const std::string &s) {
        return std::unique_ptr<node> (new string (s));
    }

    template <>
    std::unique_ptr<node>
    io<int>::serialise (const int &i) {
        return std::unique_ptr<node> (new number (i));
    }

    template <>
    std::unique_ptr<node>
    io<size_t>::serialise (const size_t &i) {
        return std::unique_ptr<node> (new number (i));
    }

    template <>
    std::unique_ptr<node>
    io<float>::serialise (const float &f) {
        return std::unique_ptr<node> (new number (f));
    }
} }


//-----------------------------------------------------------------------------
std::ostream&
operator<< (std::ostream &os, json::flat::type t)
{
    switch (t) {
    case json::flat::type::STRING:  os << "STRING";     break;
    case json::flat::type::NUL:     os << "NUL";        break;
    case json::flat::type::BOOLEAN: os << "BOOLEAN";    break;
    case json::flat::type::INTEGER: os << "INTEGER";    break;
    case json::flat::type::REAL:    os << "REAL";       break;

    case json::flat::type::OBJECT_BEGIN:    os << "OBJECT_BEGIN";   break;
    case json::flat::type::OBJECT_END:      os << "OBJECT_END";     break;
    case json::flat::type::ARRAY_BEGIN:     os << "ARRAY_BEGIN";    break;
    case json::flat::type::ARRAY_END:       os << "ARRAY_END";      break;

    default:
        unreachable ();
    }

    return os;
}