/*
 * This Source Code Form is subject to the terms of the Mozilla Public
 * License, v. 2.0. If a copy of the MPL was not distributed with this
 * file, You can obtain one at http://mozilla.org/MPL/2.0/.
 *
 * Copyright 2019 Danny Robson <danny@nerdcruft.net>
 */

#include "emory/chunk/find.hpp"
#include "emory/chunk/region.hpp"
#include "emory/chunk/params.hpp"
#include "emory/chunk/ostream.hpp"

#include <cruft/util/io.hpp>
#include <cruft/util/view.hpp>
#include <cruft/util/parse/value.hpp>
#include <cruft/util/posix/except.hpp>

#include <fmt/format.h>
#include <fmt/compile.h>

#include <algorithm>
#include <compare>
#include <filesystem>
#include <fstream>
#include <iostream>


///////////////////////////////////////////////////////////////////////////////
static
std::strong_ordering
region_ordering (
    emory::chunk::region const &a,
    emory::chunk::region const &b
) {
    if (auto const cmp = a.size () <=> b.size (); cmp != 0)
        return cmp;
    for (int i = 0; i < std::ssize (a.digest); ++i)
        if (auto const cmp = a.digest[i] <=> b.digest[i]; cmp != 0)
            return cmp;
    return std::strong_ordering::equal;
}


static bool region_less (emory::chunk::region const &a, emory::chunk::region const &b)
{
    return region_ordering (a, b) < 0;
}


static bool region_equal (emory::chunk::region const &a, emory::chunk::region const &b)
{
    return region_ordering (a, b) == 0;
}


//static bool overlap (emory::chunk::region const &a, emory::chunk::region const &b)
//{
//    return a.offset.first < b.offset.second &&
//           b.offset.first < a.offset.second;
//}


///////////////////////////////////////////////////////////////////////////////
static void find_path_chunks (
    std::vector<emory::chunk::region> &res,
    std::filesystem::path const &src,
    emory::chunk::params const &p
);


//-----------------------------------------------------------------------------
static
void
find_regular_chunks (
    std::vector<emory::chunk::region> &res,
    std::filesystem::path const &src,
    emory::chunk::params const &p
) {
    try {
        emory::chunk::find<emory::chunk::static_hash> (
            std::back_inserter (res),
            cruft::mapped_file (src),
            p
        );
    } catch (cruft::posix::error &err) {
        fmt::print (stderr, "skipping {}, error: {}\n", src.string (), err.what ());
    }
}


//-----------------------------------------------------------------------------
static
void
find_directory_chunks (
    std::vector<emory::chunk::region> &res,
    std::filesystem::path const &src,
    emory::chunk::params const &p
) {
    fmt::print (stderr, "{}\n", src.string ());
    for (auto const &child: std::filesystem::directory_iterator (src)) {
        find_path_chunks (res, child, p);
    }
}


//-----------------------------------------------------------------------------
static void find_path_chunks (
    std::vector<emory::chunk::region> &res,
    std::filesystem::path const &src,
    emory::chunk::params const &p
) {
    switch (auto const type = status (src).type (); type) {
    case std::filesystem::file_type::regular:
        return find_regular_chunks (res, src, p);

    case std::filesystem::file_type::directory:
        return find_directory_chunks (res, src, p);

    case std::filesystem::file_type::none:
    case std::filesystem::file_type::not_found:
    case std::filesystem::file_type::symlink:
    case std::filesystem::file_type::block:
    case std::filesystem::file_type::character:
    case std::filesystem::file_type::fifo:
    case std::filesystem::file_type::socket:
    case std::filesystem::file_type::unknown:
        fmt::print (stderr, "skipping path of unhandled type: '{}'\n", src.string ());
        return;
    }

    unreachable ();
}


//-----------------------------------------------------------------------------
static
std::vector<emory::chunk::region>
find_chunks (std::filesystem::path const &src, emory::chunk::params const &p)
{
    std::vector<emory::chunk::region> res;
    find_path_chunks (res, src, p);
    return res;
}


///////////////////////////////////////////////////////////////////////////////
enum {
    ARG_SELF,

    ARGS_INPUT,
    ARGS_OUTPUT,

    ARG_BITS,
    ARG_WINDOW,
    ARG_MINIMUM,
    ARG_MAXIMUM,

    NUM_ARGS,
    NUM_ARGS_REQUIRED = 3,
};


//-----------------------------------------------------------------------------
int main (int argc, char const **argv)
{
    if (argc < NUM_ARGS_REQUIRED) {
        std::cerr << "usage: " << argv[ARG_SELF] << " <input> <output> [bits] [window] [minimum] [maximum]\n"
                  << "default bits = "    << emory::chunk::DEFAULT_PARAMS.bits    << '\n'
                  << "default window = "  << emory::chunk::DEFAULT_PARAMS.window  << '\n'
                  << "default minimum = " << emory::chunk::DEFAULT_PARAMS.minimum << '\n'
                  << "default maximum = " << emory::chunk::DEFAULT_PARAMS.maximum << '\n';
        return EXIT_FAILURE;
    }

    emory::chunk::params p = emory::chunk::DEFAULT_PARAMS;
    if (argc > ARG_BITS)
        p.bits = cruft::parse::from_string<std::size_t> (argv[ARG_BITS]);
    if (argc > ARG_WINDOW)
        p.window = cruft::parse::from_string<std::size_t> (argv[ARG_WINDOW]);
    if (argc > ARG_MINIMUM)
        p.minimum = cruft::parse::from_string<std::size_t> (argv[ARG_MINIMUM]);
    if (argc > ARG_MAXIMUM)
        p.maximum = cruft::parse::from_string<std::size_t> (argv[ARG_MAXIMUM]);

    std::cerr << p << '\n';

    std::ofstream output (argv[ARGS_OUTPUT], std::ios::out | std::ios::trunc);
    output.exceptions (std::ios::badbit | std::ios::eofbit | std::ios::failbit);

    std::cout << "processing\n";
    std::vector<emory::chunk::region> src = find_chunks (argv[ARGS_INPUT], p);

    fmt::print ("analysing {} chunks\n", src.size ());

    std::sort (
        src.begin (),
        src.end (),
        region_less
    );

    output << "params: " << p << '\n';
    for (auto const &chunk: src) {
        output << chunk.size() << ' ';
        for (auto const &c: chunk.digest)
            output << std::hex << std::setw (2) << std::setfill ('0') << +c;
        output << std::dec << '\n';
    }

    std::vector<off64_t> sizes;
    std::transform (
        src.begin (),
        src.end   (),
        std::back_inserter (sizes),
        [] (auto const &val) { return val.size (); }
    );
    auto const myaccum = std::accumulate (std::begin (sizes), std::end (sizes), 0);
    std::cout << myaccum << '\n';

    auto const total_bytes = std::accumulate (
        src.begin (),
        src.end   (),
        std::uintmax_t (0),
        [] (auto const accum, auto const rhs)
    {
        return accum + rhs.size ();
    });


    std::vector<emory::chunk::region> unique;
    std::unique_copy (
        src.begin (),
        src.end   (),
        std::back_inserter (unique),
        region_equal
    );
    auto const unique_bytes = std::accumulate (
        unique.begin (),
        unique.end   (),
        0, [] (auto const accum, auto const rhs) { return accum + rhs.size (); }
    );

    auto const duplicated_bytes = total_bytes - unique_bytes;
    float const duplicated_fraction = float (duplicated_bytes) / total_bytes;

    fmt::print (
        "{} duplicated bytes of {} ({:.2f}%)\n",
        duplicated_bytes,
        total_bytes,
        100.f * duplicated_fraction
    );

    fmt::print ("{} duplicates\n", src.size () - unique.size ());
}