// panel_calendar.cpp — MVP monthly calendar view.
//
// Renders a simple 7-column grid for the current month with cards bucketed
// by `due_date`. No navigation, no editing — that's tracked as TODO in
// app.md ## Gotchas.
#include "panels.h"
#include "core/icons_tabler.h"

#include <imgui.h>
#include <ctime>
#include <mutex>

namespace kanban_cpp {

void draw_calendar(AppState& s, bool* p_open) {
    if (!ImGui::Begin(TI_CALENDAR " Calendar", p_open)) {
        ImGui::End();
        return;
    }

    std::time_t now = std::time(nullptr);
    std::tm tm_now;
#ifdef _WIN32
    localtime_s(&tm_now, &now);
#else
    localtime_r(&now, &tm_now);
#endif

    // Heading
    static const char* months[] = {"Enero","Febrero","Marzo","Abril","Mayo","Junio",
                                   "Julio","Agosto","Septiembre","Octubre","Noviembre","Diciembre"};
    ImGui::Text("%s %d", months[tm_now.tm_mon], tm_now.tm_year + 1900);
    ImGui::TextDisabled("(MVP estatico — TODO: navegacion + filtros)");
    ImGui::Separator();

    std::vector<Card> cards_snap;
    {
        std::lock_guard<std::mutex> lock(s.mu);
        cards_snap = s.cards;
    }

    // First day of current month + days in month
    std::tm tm_first = tm_now;
    tm_first.tm_mday = 1;
    std::mktime(&tm_first);
    int first_wday = tm_first.tm_wday;            // 0 = Sunday
    int first_wday_mon = (first_wday + 6) % 7;    // 0 = Monday (ES convention)

    int days_in_month = 31;
    {
        std::tm tm_test = tm_now;
        tm_test.tm_mday = 32;
        std::mktime(&tm_test);
        days_in_month = 32 - tm_test.tm_mday;
    }

    // Grid 7 cols
    if (ImGui::BeginTable("##cal", 7, ImGuiTableFlags_Borders | ImGuiTableFlags_SizingStretchSame)) {
        const char* wdays[] = {"L","M","X","J","V","S","D"};
        for (int i = 0; i < 7; ++i) ImGui::TableSetupColumn(wdays[i]);
        ImGui::TableHeadersRow();

        int day = 1;
        int total_cells = first_wday_mon + days_in_month;
        int rows = (total_cells + 6) / 7;
        int cell_index = 0;

        for (int r = 0; r < rows; ++r) {
            ImGui::TableNextRow();
            for (int c = 0; c < 7; ++c) {
                ImGui::TableSetColumnIndex(c);
                if (cell_index < first_wday_mon || day > days_in_month) {
                    ImGui::TextDisabled(" ");
                } else {
                    ImGui::Text("%d", day);
                    // Count cards whose due_date falls in this day.
                    int hits = 0;
                    for (const auto& card : cards_snap) {
                        if (card.due_date == 0) continue;
                        std::time_t cd = (std::time_t)card.due_date;
                        std::tm tmc;
#ifdef _WIN32
                        localtime_s(&tmc, &cd);
#else
                        localtime_r(&cd, &tmc);
#endif
                        if (tmc.tm_year == tm_now.tm_year && tmc.tm_mon == tm_now.tm_mon
                            && tmc.tm_mday == day) ++hits;
                    }
                    if (hits > 0)
                        ImGui::TextColored(ImVec4(0.6f, 0.55f, 0.95f, 1.0f),
                                           TI_FLAG " %d", hits);
                    ++day;
                }
                ++cell_index;
            }
        }
        ImGui::EndTable();
    }

    ImGui::End();
}

} // namespace kanban_cpp