#include <imgui.h>
#include <imgui_stdlib.h>

#include "log.h"
#include "config.h"
#include "logcat_thread.h"

static std::string leftpad(std::string str, size_t characters) {
    if (str.size() < characters) {
        return str.insert(0, characters - str.size(), ' ');
    }
    return str;
}

static inline void write_config_and_update_structures(const Config& config) {
    try {
        write_config(config);
    } catch (const std::exception& e) {
        log(std::string("Failed to write config: ") + e.what());
        return;
    }
}

static inline void check_for_logcat_items(LogcatThread& logcat_thread, std::vector<LogcatEntry>& filtered_logcat_entries) {
    LogcatThreadItem* logcat_thread_item;

    while ((logcat_thread_item = logcat_thread.atomic_ring_buffer.get())) {
        if (std::holds_alternative<std::string>(*logcat_thread_item)) {
            log_raw(std::move(std::get<std::string>(*logcat_thread_item)), false);
        } else if (std::holds_alternative<LogcatEntry>(*logcat_thread_item)) {
            filtered_logcat_entries.push_back(std::move(std::get<LogcatEntry>(*logcat_thread_item)));
        } else {
            throw std::runtime_error("Cannot handle all possible logcat thread item variants");
        }
        logcat_thread.atomic_ring_buffer.increment_read();
    }
}


static inline void settings_window(Config& config, float* config_write_timer, bool* show_settings_window) {
    if (!ImGui::Begin("Settings", show_settings_window)) {
        ImGui::End();
        return;
    }
    // TODO actually have process control
    ImGui::Text("Logcat command only takes effect when logcat is not running");
    if (ImGui::InputTextWithHint("Logcat command", "adb logcat -Dv 'threadtime UTC epoch usec uid'", &config.logcat_command)) {
        *config_write_timer = *config_write_timer > 0.0f ? *config_write_timer : 5.0f;
    }
    ImGui::Text("Font sizes only take effect when LogMeow is restarted");
#ifdef USE_FONTCONFIG
    if (ImGui::InputFloat("Normal font size", &config.normal_font_size, 0.5f, 1.0f, "%.3f")) {
        *config_write_timer = *config_write_timer > 0.0f ? *config_write_timer : 5.0f;
    }
#endif
    if (ImGui::InputFloat("Monospace font size", &config.monospace_font_size, 0.5f, 1.0f, "%.3f")) {
        *config_write_timer = *config_write_timer > 0.0f ? *config_write_timer : 5.0f;
    }
    ImGui::End();
}

static inline void logs_window(ImFont* monospace_font, bool* autoscrolling, bool* show_logs_window) {
    if (!ImGui::Begin("LogMeow Logs", show_logs_window)) {
        ImGui::End();
        return;
    }

    if (ImGui::Button("Clear")) {
        log_entries.clear();
        log_entry_line_offsets = {0};
    }
    ImGui::SameLine();
    if (ImGui::Button("Copy")) {
        ImGui::SetClipboardText(log_entries.c_str());
    }

    ImGui::Separator();
    // copied from imgui/imgui_demo.cpp: [SECTION] Example App: Debug Console / ShowExampleAppConsole()
    // and [SECTION] Example App: Long Text / ShowExampleAppLongText()
    // and [SECTION] Example App: Debug Log / ShowExampleAppLog()
    if (ImGui::BeginChild("ScrollingRegion", ImVec2(0, 0), false, ImGuiWindowFlags_HorizontalScrollbar)) {
        ImGui::PushFont(monospace_font);
        ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(0, 0));

        ImGuiListClipper clipper;
        clipper.Begin(static_cast<int>(log_entry_line_offsets.size()));
        while (clipper.Step()) {
            for (int i_u = clipper.DisplayStart; i_u < clipper.DisplayEnd; i_u++) {
                // what'd we do if we log the error about an error failing to show logs
                assert(i_u >= 0);
                size_t i = static_cast<size_t>(i_u);

                const char* start_offset = &log_entries[log_entry_line_offsets[i]];
                const char* end_offset = log_entry_line_offsets.size() > i + 1
                    ? &log_entries[log_entry_line_offsets[i + 1] - 1]
                    : &log_entries[log_entries.size()];
                ImGui::TextUnformatted(start_offset, end_offset);
            }
        }
        clipper.End();

        ImGui::PopStyleVar();
        ImGui::PopFont();
        if (ImGui::GetScrollY() >= ImGui::GetScrollMaxY()) {
            *autoscrolling = true;
            ImGui::SetScrollHereY(1.0f);
        }
    }
    ImGui::EndChild();
    ImGui::End();
}

static inline void main_window(bool latest_log_entries_read, ImFont* monospace_font, std::vector<LogcatEntry>& filtered_logcat_entries,
        bool* show_settings_window, bool* show_logs_window, bool* run_event_loop) {
    if (!ImGui::Begin("LogMeow", run_event_loop)) {
        ImGui::End();
        return;
    }

    if (ImGui::Button("Settings")) {
        *show_settings_window = true;
    }

    ImGui::SameLine();
    if (!latest_log_entries_read) {
        ImGui::PushStyleColor(ImGuiCol_Button, (ImVec4)ImColor::HSV(0.0f, 0.6f, 0.6f));
        ImGui::PushStyleColor(ImGuiCol_ButtonHovered, (ImVec4)ImColor::HSV(0.0f, 0.7f, 0.7f));
        ImGui::PushStyleColor(ImGuiCol_ButtonActive, (ImVec4)ImColor::HSV(0.0f, 0.8f, 0.8f));
    }
    if (ImGui::Button("Logs")) {
        *show_logs_window = true;
    }
    if (!latest_log_entries_read) {
        ImGui::PopStyleColor(3);
    }

    ImGui::Separator();
    // copied from imgui/imgui_demo.cpp: [SECTION] Example App: Debug Console / ShowExampleAppConsole()
    // and [SECTION] Example App: Long Text / ShowExampleAppLongText()
    // and [SECTION] Example App: Debug Log / ShowExampleAppLog()
    if (ImGui::BeginChild("ScrollingRegion", ImVec2(0, 0), false, ImGuiWindowFlags_HorizontalScrollbar)) {
        ImGui::PushFont(monospace_font);
        ImGui::PushStyleVar(ImGuiStyleVar_ItemSpacing, ImVec2(0, 0));

        ImGuiListClipper clipper;
        clipper.Begin(static_cast<int>(filtered_logcat_entries.size()));
        while (clipper.Step()) {
            for (int i = clipper.DisplayStart; i < clipper.DisplayEnd; i++) {
                LogcatEntry* logcat_entry = &filtered_logcat_entries[static_cast<size_t>(i)];
                char time_as_str[128] = {0};
                strftime(time_as_str, 127 * sizeof(char), "%c", localtime(&logcat_entry->time));

                std::string header = std::string(1, '[') + time_as_str + ' '
                    + leftpad(logcat_entry->user.value_or("     "), 5) + ' '
                    + leftpad(std::to_string(logcat_entry->pid), 5) + ' '
                    + leftpad(std::to_string(logcat_entry->tid), 5) + ' '
                    + leftpad(buffer_to(logcat_entry->buffer), 6) + ' '
                    + leftpad(priority_to(logcat_entry->priority), 7) + "] ";
                ImGui::PushStyleColor(ImGuiCol_Text, ImGui::GetStyle().Colors[ImGuiCol_TextDisabled]);
                ImGui::TextUnformatted(header.data(), &header[header.size()]);
                ImGui::PopStyleColor();

                std::string line = logcat_entry->tag + ": " + logcat_entry->message;
                ImGui::SameLine();
                ImGui::TextUnformatted(line.data(), &line[line.size()]);
            }
        }
        clipper.End();

        ImGui::PopStyleVar();
        ImGui::PopFont();
        if (ImGui::GetScrollY() >= ImGui::GetScrollMaxY()) {
            ImGui::SetScrollHereY(1.0f);
        }
    }
    ImGui::EndChild();
    ImGui::End();
}

#ifndef NDEBUG
static inline void debug_window(LogcatThread& logcat_thread) {
    static bool show_demo_window = false;
    static size_t add_log_entry_presses = 1;
    static bool log_entry_every_second = false;
    static float log_entry_every_second_delta;

    if (show_demo_window) {
        ImGui::ShowDemoWindow(&show_demo_window);
    }
    if (!ImGui::Begin("LogMeow Debug")) {
        ImGui::End();
        return;
    }

    ImGui::Text("Application average %.3f ms/frame (%.1f FPS)", 1000.0f / ImGui::GetIO().Framerate, ImGui::GetIO().Framerate);
    ImGui::Checkbox("Show Dear ImGui Demo Window", &show_demo_window);

    ImGui::Separator();
    if (ImGui::Button("Add Log Entry")) {
        log(std::string("Debug log entry #") + std::to_string(add_log_entry_presses++) + " (activated via manual button press)");
    }
    ImGui::SameLine();
    // returns true when it's pressed
    if (ImGui::Checkbox("Add log entry every second", &log_entry_every_second)) {
        log_entry_every_second_delta = 0.0f;
    }
    if (ImGui::Button("Add Log Entry with Newlines")) {
        log("The following should have five spaces: \"\n\n\n\n\n\"");
    }
    if (ImGui::Button("Test user assert")) {
        IM_ASSERT_USER_ERROR(0, "User assert tested");
    }
    if (ImGui::Button("Request log entry from Logcat thread")) {
        logcat_thread.debug_log_request.test_and_set();
    }

    if (log_entry_every_second) {
        log_entry_every_second_delta += ImGui::GetIO().DeltaTime;
        if (log_entry_every_second_delta >= 1.0f) {
            log_entry_every_second_delta = 0.0f;
            log(std::string("Debug log entry #") + std::to_string(add_log_entry_presses++) + " (activated by add log entry every second)");
        }
    }

    ImGui::End();
}
#endif

void event_loop(ImFont* monospace_font, Config& config, float* config_write_timer, LogcatThread& logcat_thread, bool* run_event_loop) {
    static bool show_settings_window = false;
    static bool show_logs_window = false;
    static size_t log_entries_read = 0;
    static std::vector<LogcatEntry> filtered_logcat_entries;

    check_for_logcat_items(logcat_thread, filtered_logcat_entries);

#ifndef NDEBUG
    debug_window(logcat_thread);
#endif

    if (show_settings_window) {
        settings_window(config, config_write_timer, &show_settings_window);
    }
    if (*config_write_timer > 0.0f) {
        *config_write_timer -= ImGui::GetIO().DeltaTime;
        if (*config_write_timer <= 0.0f) {
            write_config_and_update_structures(config);
        }
    }

    if (show_logs_window) {
        bool autoscrolling = false;
        logs_window(monospace_font, &autoscrolling, &show_logs_window);
        if (autoscrolling) {
            log_entries_read = log_entries.size();
        }
    }

    // log_entries must not be mutated until the show logs button
    main_window(log_entries_read == log_entries.size(), monospace_font, filtered_logcat_entries, &show_settings_window, &show_logs_window, run_event_loop);
}