/**
 * Copyright (c) 2007-2012, Timothy Stack
 *
 * All rights reserved.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions are met:
 *
 * * Redistributions of source code must retain the above copyright notice, this
 * list of conditions and the following disclaimer.
 * * Redistributions in binary form must reproduce the above copyright notice,
 * this list of conditions and the following disclaimer in the documentation
 * and/or other materials provided with the distribution.
 * * Neither the name of Timothy Stack nor the names of its contributors
 * may be used to endorse or promote products derived from this software
 * without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ''AS IS'' AND ANY
 * EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
 * WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
 * DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE FOR ANY
 * DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES
 * (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES;
 * LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND
 * ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
 * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS
 * SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
 *
 * @file hist_source.hh
 */

#ifndef hist_source_hh
#define hist_source_hh

#include <cmath>
#include <cstdint>
#include <limits>
#include <optional>
#include <string>
#include <unordered_map>
#include <vector>

#include "base/enum_util.hh"
#include "base/lnav_log.hh"
#include "mapbox/variant.hpp"
#include "strong_int.hh"
#include "textview_curses.hh"

/** Type for indexes into a group of buckets. */
STRONG_INT_TYPE(int, bucket_group);

/** Type used to differentiate values added to the same row in the histogram */
STRONG_INT_TYPE(int, bucket_type);

struct stacked_bar_chart_base {
    virtual ~stacked_bar_chart_base() = default;

    struct show_none {};
    struct show_all {};
    struct show_one {
        size_t so_index;

        explicit show_one(int so_index) : so_index(so_index) {}
    };

    using show_state = mapbox::util::variant<show_none, show_all, show_one>;

    enum class direction {
        forward,
        backward,
    };
};

struct bucket_stats_t {
    void merge(const bucket_stats_t& rhs)
    {
        this->bs_min_value = std::min(this->bs_min_value, rhs.bs_min_value);
        this->bs_max_value = std::max(this->bs_max_value, rhs.bs_max_value);
    }

    double width() const
    {
        return std::fabs(this->bs_max_value - this->bs_min_value);
    }

    void update(double value)
    {
        this->bs_max_value = std::max(this->bs_max_value, value);
        this->bs_min_value = std::min(this->bs_min_value, value);
    }

    double bs_min_value = std::numeric_limits<double>::max();
    double bs_max_value = std::numeric_limits<double>::min();
};

template<typename T>
class stacked_bar_chart : public stacked_bar_chart_base {
public:

    struct chart_ident {
        explicit chart_ident(const T& ident) : ci_ident(ident) {}

        T ci_ident;
        text_attrs ci_attrs;
        bucket_stats_t ci_stats;
        ssize_t ci_last_seen_row{-1};
    };

    stacked_bar_chart& with_stacking_enabled(bool enabled)
    {
        this->sbc_do_stacking = enabled;
        return *this;
    }

    stacked_bar_chart& with_attrs_for_ident(const T& ident, text_attrs attrs)
    {
        auto& ci = this->find_ident(ident);
        ci.ci_attrs = attrs;
        return *this;
    }

    stacked_bar_chart& with_margins(unsigned long left, unsigned long right)
    {
        this->sbc_left = left;
        this->sbc_right = right;
        return *this;
    }

    stacked_bar_chart& with_show_state(show_state ss)
    {
        this->sbc_show_state = ss;
        return *this;
    }

    bool attrs_in_use(const text_attrs& attrs) const
    {
        for (const auto& ident : this->sbc_idents) {
            if (ident.ci_attrs == attrs) {
                return true;
            }
        }
        return false;
    }

    show_state show_next_ident(direction dir)
    {
        bool single_ident = this->sbc_idents.size() == 1;

        if (this->sbc_idents.empty()) {
            return this->sbc_show_state;
        }

        this->sbc_show_state = this->sbc_show_state.match(
            [&](show_none) -> show_state {
                switch (dir) {
                    case direction::forward:
                        if (single_ident) {
                            return show_all();
                        }
                        return show_one(0);
                    case direction::backward:
                        return show_all();
                }

                return show_all();
            },
            [&](show_one& one) -> show_state {
                switch (dir) {
                    case direction::forward:
                        if (one.so_index + 1 == this->sbc_idents.size()) {
                            return show_all();
                        }
                        return show_one(one.so_index + 1);
                    case direction::backward:
                        if (one.so_index == 0) {
                            return show_none();
                        }
                        return show_one(one.so_index - 1);
                }

                return show_all();
            },
            [&](show_all) -> show_state {
                switch (dir) {
                    case direction::forward:
                        return show_none();
                    case direction::backward:
                        if (single_ident) {
                            return show_none();
                        }
                        return show_one(this->sbc_idents.size() - 1);
                }

                return show_all();
            });

        return this->sbc_show_state;
    }

    void get_ident_to_show(T& ident_out) const
    {
        this->sbc_show_state.match(
            [](const show_none) {},
            [](const show_all) {},
            [&](const show_one& one) {
                ident_out = this->sbc_idents[one.so_index].ci_ident;
            });
    }

    void chart_attrs_for_value(const listview_curses& lc,
                               int& left,
                               unsigned long width,
                               const T& ident,
                               double value,
                               string_attrs_t& value_out,
                               std::optional<text_attrs> user_attrs
                               = std::nullopt) const;

    void clear()
    {
        this->sbc_idents.clear();
        this->sbc_ident_lookup.clear();
        this->sbc_show_state = show_none();
        this->sbc_row_sum = 0;
        this->sbc_row_items = 0;
        this->sbc_max_row_value = 0;
        this->sbc_max_row_items = 0;
    }

    chart_ident& add_value(const T& ident, double amount = 1.0)
    {
        auto& ci = this->find_ident(ident);
        ci.ci_stats.update(amount);
        this->sbc_row_sum += amount;
        if (ci.ci_last_seen_row != this->sbc_row_counter) {
            ci.ci_last_seen_row = this->sbc_row_counter;
            this->sbc_row_items += 1;
        }

        return ci;
    }

    void next_row()
    {
        if (this->sbc_row_sum > this->sbc_max_row_value) {
            this->sbc_max_row_value = this->sbc_row_sum;
        }
        if (this->sbc_row_items > this->sbc_max_row_items) {
            this->sbc_max_row_items = this->sbc_row_items;
        }
        this->sbc_row_sum = 0;
        this->sbc_row_items = 0;
        this->sbc_row_counter += 1;
    }

    const bucket_stats_t& get_stats_for(const T& ident)
    {
        const chart_ident& ci = this->find_ident(ident);

        return ci.ci_stats;
    }

protected:

    chart_ident& find_ident(const T& ident)
    {
        auto iter = this->sbc_ident_lookup.find(ident);
        if (iter == this->sbc_ident_lookup.end()) {
            this->sbc_ident_lookup[ident] = this->sbc_idents.size();
            this->sbc_idents.emplace_back(ident);
            return this->sbc_idents.back();
        }
        return this->sbc_idents[iter->second];
    }

    bool sbc_do_stacking{true};
    unsigned long sbc_left{0}, sbc_right{0};
    std::vector<chart_ident> sbc_idents;
    std::unordered_map<T, unsigned int> sbc_ident_lookup;
    show_state sbc_show_state{show_none()};

    ssize_t sbc_row_counter{0};
    double sbc_row_sum{0};
    size_t sbc_row_items{0};
    double sbc_max_row_value{0};
    size_t sbc_max_row_items{0};
};

class hist_source2
    : public text_sub_source
    , public text_time_translator {
public:
    enum class hist_type_t : uint8_t {
        normal,
        warning,
        error,
        mark,

        HT__MAX
    };

    hist_source2();

    ~hist_source2() override = default;

    bool empty() const override { return false; }

    void init();

    void set_time_slice(std::chrono::microseconds slice)
    {
        this->hs_time_slice = slice;
    }

    std::chrono::microseconds get_time_slice() const
    {
        return this->hs_time_slice;
    }

    size_t text_line_count() override { return this->hs_line_count; }

    size_t text_line_width(textview_curses& curses) override;

    void clear();

    void add_value(std::chrono::microseconds ts,
                   hist_type_t htype,
                   double value = 1.0);

    void end_of_row();

    line_info text_value_for_line(textview_curses& tc,
                                  int row,
                                  std::string& value_out,
                                  line_flags_t flags) override;

    void text_attrs_for_line(textview_curses& tc,
                             int row,
                             string_attrs_t& value_out) override;

    size_t text_size_for_line(textview_curses& tc,
                              int row,
                              line_flags_t flags) override
    {
        return 0;
    }

    std::optional<row_info> time_for_row(vis_line_t row) override;

    std::optional<vis_line_t> row_for_time(timeval tv_bucket) override;

private:
    struct hist_value {
        double hv_value{0};
    };

    struct bucket_t {
        std::chrono::microseconds b_time;
        hist_value b_values[lnav::enums::to_underlying(hist_type_t::HT__MAX)];

        hist_value& value_for(hist_type_t ht)
        {
            return this->b_values[lnav::enums::to_underlying(ht)];
        }

        const hist_value& value_for(hist_type_t ht) const
        {
            return this->b_values[lnav::enums::to_underlying(ht)];
        }

        bool empty() const;
    };

    static constexpr int64_t BLOCK_SIZE = 100;

    struct bucket_block {
        unsigned int bb_used{0};
        bucket_t bb_buckets[BLOCK_SIZE];
    };

    bucket_t& find_bucket(int64_t index);

    std::chrono::microseconds hs_time_slice;
    int64_t hs_line_count{0};
    int64_t hs_current_row{0};
    std::chrono::microseconds hs_last_ts;
    std::vector<bucket_block> hs_blocks;
    stacked_bar_chart<hist_type_t> hs_chart;
    bool hs_needs_flush{false};
};

#endif
