// Copyright (c) 2019, QuantStack and Mamba Contributors
//
// Distributed under the terms of the BSD 3-Clause License.
//
// The full license is in the file LICENSE, distributed with this software.

#ifndef MAMBA_CORE_HISTORY
#define MAMBA_CORE_HISTORY

#include <string>
#include <unordered_map>
#include <vector>

#include "mamba/core/channel_context.hpp"
#include "mamba/core/context_params.hpp"
#include "mamba/fs/filesystem.hpp"
#include "mamba/specs/match_spec.hpp"
#include "mamba/specs/package_info.hpp"

namespace mamba
{
    class History
    {
    public:

        History(const fs::u8path& prefix, ChannelContext& channel_context);

        struct ParseResult
        {
            std::string head_line;
            std::vector<std::string> diff;
            std::vector<std::string> comments;
        };

        struct UserRequest
        {
            static UserRequest prefilled(const CommandParams& command_params);

            std::string date;
            std::size_t revision_num = 0;
            std::string cmd;
            std::string conda_version;

            std::vector<std::string> unlink_dists;
            std::vector<std::string> link_dists;

            std::vector<std::string> update;
            std::vector<std::string> remove;
            std::vector<std::string> neutered;
        };

        std::vector<ParseResult> parse();
        bool parse_comment_line(const std::string& line, UserRequest& req);
        std::vector<UserRequest> get_user_requests();
        std::unordered_map<std::string, specs::MatchSpec> get_requested_specs_map();
        void add_entry(const History::UserRequest& entry);

        fs::u8path m_prefix;
        fs::u8path m_history_file_path;
        ChannelContext& m_channel_context;
    };

    /** PackageDiff contains two maps of packages and their package info, one being for the
     * installed packages, the other for the removed ones. This is used while looping on
     * revisions to get the diff between the target revision and the current one.
     */
    struct PackageDiff
    {
        using package_diff_map = std::unordered_map<std::string, specs::PackageInfo>;
        package_diff_map removed_pkg_diff;
        package_diff_map installed_pkg_diff;

        [[nodiscard]] static PackageDiff
        from_revision(const std::vector<History::UserRequest>& user_requests, std::size_t target_revision);
    };

    /** The following function parses the different formats that can be found in the history
     * file.
     *
     * conda/mamba1 format:
     *
     * installed: +conda-forge/linux-64::xtl-0.8.0-h84d6215_0
     * removed: -conda-forge/linux-64::xtl-0.8.0-h84d6215_0
     *
     * mamba2 broken format:
     *
     * installed: +conda-forge::xtl-0.8.0-h84d6215_0
     * removed: -https://conda.anaconda.org/conda-forge/linux-64::xtl-0.8.0-h84d6215_0
     *
     * mamba2 new format:
     * installed: +https://conda.anaconda.org/conda-forge/linux-64::xtl-0.8.0-h84d6215_0
     * removed: -https://conda.anaconda.org/conda-forge/linux-64::xtl-0.8.0-h84d6215_0
     */
    specs::PackageInfo read_history_url_entry(const std::string& s);
}  // namespace mamba

#endif