/*
 * main.cpp
 * MontaukOS Process Manager
 * Copyright (c) 2026 Daniel Hammer
 */

#include <montauk/syscall.h>
#include <montauk/string.h>
#include <montauk/heap.h>
#include <gui/mtk.hpp>

extern "C" {
#include <stdio.h>
}

using namespace gui;

static constexpr int INIT_W         = 760;
static constexpr int INIT_H         = 520;
static constexpr int PM_TOOLBAR_H   = 36;
static constexpr int PM_TAB_H       = 32;
static constexpr int PM_HEADER_H    = 24;
static constexpr int PM_ITEM_H      = 28;
static constexpr int PM_POLL_MS     = 1000;
static constexpr int PM_MAX_PROCS   = 256;
static constexpr int PM_MAX_WINDOWS = 64;
static constexpr int PM_GRAPH_CAP   = 120;

static constexpr Color PM_TOOLBAR_BG = Color::from_rgb(0xF5, 0xF5, 0xF5);
static constexpr Color PM_HEADER_BG  = Color::from_rgb(0xF0, 0xF0, 0xF0);
static constexpr Color PM_BORDER     = Color::from_rgb(0xD0, 0xD0, 0xD0);
static constexpr Color PM_DIM_TEXT   = Color::from_rgb(0x66, 0x66, 0x66);
static constexpr Color PM_SUCCESS    = Color::from_rgb(0x22, 0x88, 0x22);
static constexpr Color PM_WARNING    = Color::from_rgb(0xCC, 0x88, 0x00);
static constexpr Color PM_DANGER     = Color::from_rgb(0xCC, 0x33, 0x33);
static constexpr Color PM_INFO       = Color::from_rgb(0x33, 0x66, 0xCC);

enum ProcMgrTab {
    PM_TAB_PROCESSES   = 0,
    PM_TAB_PERFORMANCE = 1,
    PM_TAB_WINDOWS     = 2,
    PM_TAB_COUNT       = 3,
};

static const char* g_tab_labels[PM_TAB_COUNT] = {
    "Processes",
    "Performance",
    "Windows",
};

struct ProcCpuSnapshot {
    int pid;
    uint64_t cpu_time_ms;
};

struct ProcMgrState {
    Montauk::ProcInfo procs[PM_MAX_PROCS];
    Montauk::WinInfo windows[PM_MAX_WINDOWS];
    Montauk::MemStats mem;
    Montauk::SysInfo sys_info;
    int proc_count;
    int win_count;
    int selected;
    int selected_window;
    int proc_scroll;
    int win_scroll;
    int active_tab;
    int mouse_x;
    int mouse_y;
    int cpu_count;
    int cpu_percent;
    int mem_percent;
    uint64_t total_process_heap;
    uint64_t last_poll_ms;
    uint64_t last_cpu_wall_ms;
    bool have_cpu_sample;

    ProcCpuSnapshot prev_cpu[PM_MAX_PROCS];
    int prev_cpu_count;

    uint64_t cpu_samples[PM_GRAPH_CAP];
    uint64_t mem_samples[PM_GRAPH_CAP];
    uint64_t proc_samples[PM_GRAPH_CAP];
    uint64_t win_samples[PM_GRAPH_CAP];
    uint64_t heap_samples[PM_GRAPH_CAP];
    mtk::GraphHistory cpu_history;
    mtk::GraphHistory mem_history;
    mtk::GraphHistory proc_history;
    mtk::GraphHistory win_history;
    mtk::GraphHistory heap_history;
};

static WsWindow g_win;
static ProcMgrState g_pm = {};

static mtk::Theme pm_theme() {
    mtk::Theme theme = mtk::make_theme();
    theme.surface = PM_TOOLBAR_BG;
    theme.surface_alt = PM_HEADER_BG;
    theme.border = PM_BORDER;
    theme.text_muted = PM_DIM_TEXT;
    theme.text_subtle = PM_DIM_TEXT;
    theme.danger = PM_DANGER;
    theme.danger_hover = mtk::darken(PM_DANGER, 18);
    theme.disabled_bg = Color::from_rgb(0xAA, 0xAA, 0xAA);
    return theme;
}

static void init_graph_histories() {
    mtk::graph_history_init(&g_pm.cpu_history, g_pm.cpu_samples, PM_GRAPH_CAP);
    mtk::graph_history_init(&g_pm.mem_history, g_pm.mem_samples, PM_GRAPH_CAP);
    mtk::graph_history_init(&g_pm.proc_history, g_pm.proc_samples, PM_GRAPH_CAP);
    mtk::graph_history_init(&g_pm.win_history, g_pm.win_samples, PM_GRAPH_CAP);
    mtk::graph_history_init(&g_pm.heap_history, g_pm.heap_samples, PM_GRAPH_CAP);
}

static int parse_positive_int_after_comma(const char* text) {
    if (!text) return 0;
    const char* p = text;
    while (*p && *p != ',') p++;
    if (*p == ',') p++;

    while (*p && (*p < '0' || *p > '9')) p++;
    int value = 0;
    while (*p >= '0' && *p <= '9') {
        value = value * 10 + (*p - '0');
        p++;
    }
    return value;
}

static int detect_cpu_count() {
    Montauk::DevInfo devs[16];
    int count = montauk::devlist(devs, 16);
    if (count < 0) count = 0;

    for (int i = 0; i < count; i++) {
        if (devs[i].category != 0) continue;
        int cores = parse_positive_int_after_comma(devs[i].detail);
        if (cores > 0) return cores;
    }
    return 1;
}

static void refresh_static_info() {
    montauk::get_info(&g_pm.sys_info);
    if (g_pm.sys_info.maxProcesses == 0)
        g_pm.sys_info.maxProcesses = PM_MAX_PROCS;
    g_pm.cpu_count = detect_cpu_count();
    if (g_pm.cpu_count <= 0) g_pm.cpu_count = 1;
}

static void format_size(char* buf, uint64_t size) {
    if (size < 1024ULL) {
        snprintf(buf, 24, "%llu B", (unsigned long long)size);
    } else if (size < 1024ULL * 1024ULL) {
        uint64_t kb = size / 1024ULL;
        uint64_t frac = ((size % 1024ULL) * 10ULL) / 1024ULL;
        if (kb < 10ULL) snprintf(buf, 24, "%llu.%llu KB",
                                 (unsigned long long)kb, (unsigned long long)frac);
        else snprintf(buf, 24, "%llu KB", (unsigned long long)kb);
    } else if (size < 1024ULL * 1024ULL * 1024ULL) {
        uint64_t mb = size / (1024ULL * 1024ULL);
        uint64_t frac = ((size % (1024ULL * 1024ULL)) * 10ULL) / (1024ULL * 1024ULL);
        if (mb < 10ULL) snprintf(buf, 24, "%llu.%llu MB",
                                 (unsigned long long)mb, (unsigned long long)frac);
        else snprintf(buf, 24, "%llu MB", (unsigned long long)mb);
    } else {
        uint64_t gb = size / (1024ULL * 1024ULL * 1024ULL);
        uint64_t frac = ((size % (1024ULL * 1024ULL * 1024ULL)) * 10ULL) / (1024ULL * 1024ULL * 1024ULL);
        if (gb < 10ULL) snprintf(buf, 24, "%llu.%llu GB",
                                 (unsigned long long)gb, (unsigned long long)frac);
        else snprintf(buf, 24, "%llu GB", (unsigned long long)gb);
    }
}

static const char* proc_state_label(uint8_t state, Color* out_color) {
    Color color = colors::TEXT_COLOR;
    const char* label = "?";
    switch (state) {
    case 1:
        label = "Ready";
        color = PM_INFO;
        break;
    case 2:
        label = "Run";
        color = PM_SUCCESS;
        break;
    case 3:
        label = "Block";
        color = PM_WARNING;
        break;
    case 4:
        label = "Term";
        color = PM_DANGER;
        break;
    default:
        break;
    }
    if (out_color) *out_color = color;
    return label;
}

static int content_top() {
    return PM_TOOLBAR_H + PM_TAB_H;
}

static mtk::TableLayout process_table_layout() {
    int top = content_top();
    int body_y = top + PM_HEADER_H;
    return {
        {0, top, g_win.width, PM_HEADER_H},
        {0, body_y, g_win.width, gui_max(g_win.height - body_y, 0)},
        PM_ITEM_H
    };
}

static mtk::TableLayout window_table_layout() {
    int top = content_top();
    int body_y = top + PM_HEADER_H;
    return {
        {0, top, g_win.width, PM_HEADER_H},
        {0, body_y, g_win.width, gui_max(g_win.height - body_y, 0)},
        PM_ITEM_H
    };
}

static int process_visible_rows() {
    return mtk::table_visible_rows(process_table_layout());
}

static int window_visible_rows() {
    return mtk::table_visible_rows(window_table_layout());
}

static bool process_state_alive(uint8_t state) {
    return state == 1 || state == 2 || state == 3;
}

static int live_process_count() {
    int count = 0;
    for (int i = 0; i < g_pm.proc_count; i++) {
        if (process_state_alive(g_pm.procs[i].state))
            count++;
    }
    return count;
}

static uint64_t total_process_heap() {
    uint64_t total = 0;
    for (int i = 0; i < g_pm.proc_count; i++) {
        if (process_state_alive(g_pm.procs[i].state))
            total += g_pm.procs[i].heapUsed;
    }
    return total;
}

static void collect_descendant_pids(int parent_pid, int* pids, int* count, int max_count) {
    for (int i = 0; i < g_pm.proc_count; i++) {
        if (!process_state_alive(g_pm.procs[i].state)) continue;
        if (g_pm.procs[i].parentPid != parent_pid) continue;

        int child_pid = g_pm.procs[i].pid;
        collect_descendant_pids(child_pid, pids, count, max_count);
        if (*count < max_count)
            pids[(*count)++] = child_pid;
    }
}

static int find_prev_cpu_snapshot(int pid) {
    for (int i = 0; i < g_pm.prev_cpu_count; i++) {
        if (g_pm.prev_cpu[i].pid == pid)
            return i;
    }
    return -1;
}

static uint64_t process_cpu_delta_ms() {
    uint64_t delta = 0;
    for (int i = 0; i < g_pm.proc_count; i++) {
        int prev = find_prev_cpu_snapshot(g_pm.procs[i].pid);
        if (prev < 0) continue;
        uint64_t old_time = g_pm.prev_cpu[prev].cpu_time_ms;
        uint64_t new_time = g_pm.procs[i].cpuTimeMs;
        if (new_time >= old_time)
            delta += new_time - old_time;
    }
    return delta;
}

static void store_cpu_snapshot() {
    g_pm.prev_cpu_count = gui_min(g_pm.proc_count, PM_MAX_PROCS);
    for (int i = 0; i < g_pm.prev_cpu_count; i++) {
        g_pm.prev_cpu[i].pid = g_pm.procs[i].pid;
        g_pm.prev_cpu[i].cpu_time_ms = g_pm.procs[i].cpuTimeMs;
    }
}

static void sample_performance(uint64_t now) {
    uint64_t elapsed = g_pm.have_cpu_sample ? now - g_pm.last_cpu_wall_ms : 0;
    uint64_t cpu_delta = process_cpu_delta_ms();

    if (g_pm.have_cpu_sample && elapsed > 0) {
        uint64_t capacity = elapsed * (uint64_t)gui_max(g_pm.cpu_count, 1);
        uint64_t percent = capacity > 0 ? (cpu_delta * 100ULL) / capacity : 0;
        if (percent > 100ULL) percent = 100ULL;
        g_pm.cpu_percent = (int)percent;
    } else {
        g_pm.cpu_percent = 0;
    }

    store_cpu_snapshot();
    g_pm.have_cpu_sample = true;
    g_pm.last_cpu_wall_ms = now;

    if (g_pm.mem.totalBytes > 0) {
        g_pm.mem_percent = (int)((g_pm.mem.usedBytes * 100ULL) / g_pm.mem.totalBytes);
        if (g_pm.mem_percent > 100) g_pm.mem_percent = 100;
    } else {
        g_pm.mem_percent = 0;
    }

    g_pm.total_process_heap = total_process_heap();

    mtk::graph_history_push(&g_pm.cpu_history, (uint64_t)g_pm.cpu_percent);
    mtk::graph_history_push(&g_pm.mem_history, g_pm.mem.usedBytes);
    mtk::graph_history_push(&g_pm.proc_history, (uint64_t)live_process_count());
    mtk::graph_history_push(&g_pm.win_history, (uint64_t)g_pm.win_count);
    mtk::graph_history_push(&g_pm.heap_history, g_pm.total_process_heap);
}

static int find_process_index_by_pid(int pid) {
    for (int i = 0; i < g_pm.proc_count; i++) {
        if (g_pm.procs[i].pid == pid)
            return i;
    }
    return -1;
}

static int find_window_index_by_id(int id) {
    for (int i = 0; i < g_pm.win_count; i++) {
        if (g_pm.windows[i].id == id)
            return i;
    }
    return -1;
}

static void clamp_scrolls() {
    mtk::clamp_table_scroll(&g_pm.proc_scroll, process_table_layout(), g_pm.proc_count);
    mtk::clamp_table_scroll(&g_pm.win_scroll, window_table_layout(), g_pm.win_count);
}

static void ensure_process_selection_visible() {
    mtk::ensure_table_row_visible(&g_pm.proc_scroll, process_table_layout(),
                                  g_pm.proc_count, g_pm.selected);
}

static void ensure_window_selection_visible() {
    mtk::ensure_table_row_visible(&g_pm.win_scroll, window_table_layout(),
                                  g_pm.win_count, g_pm.selected_window);
}

static bool refresh_state(bool force) {
    uint64_t now = montauk::get_milliseconds();
    if (!force && now - g_pm.last_poll_ms < PM_POLL_MS)
        return false;

    g_pm.last_poll_ms = now;

    int prev_pid = -1;
    if (g_pm.selected >= 0 && g_pm.selected < g_pm.proc_count)
        prev_pid = g_pm.procs[g_pm.selected].pid;

    int prev_win_id = -1;
    if (g_pm.selected_window >= 0 && g_pm.selected_window < g_pm.win_count)
        prev_win_id = g_pm.windows[g_pm.selected_window].id;

    g_pm.proc_count = montauk::proclist(g_pm.procs, PM_MAX_PROCS);
    if (g_pm.proc_count < 0) g_pm.proc_count = 0;
    g_pm.selected = find_process_index_by_pid(prev_pid);

    g_pm.win_count = montauk::win_enumerate(g_pm.windows, PM_MAX_WINDOWS);
    if (g_pm.win_count < 0) g_pm.win_count = 0;
    g_pm.selected_window = find_window_index_by_id(prev_win_id);

    montauk::memstats(&g_pm.mem);
    sample_performance(now);

    clamp_scrolls();
    ensure_process_selection_visible();
    ensure_window_selection_visible();
    return true;
}

static bool can_kill_selected() {
    return g_pm.active_tab == PM_TAB_PROCESSES
        && g_pm.selected >= 0
        && g_pm.selected < g_pm.proc_count
        && g_pm.procs[g_pm.selected].pid != 0
        && g_pm.procs[g_pm.selected].state != 4;
}

static void kill_selected() {
    if (!can_kill_selected())
        return;

    int root_pid = g_pm.procs[g_pm.selected].pid;
    int descendants[PM_MAX_PROCS];
    int descendant_count = 0;
    collect_descendant_pids(root_pid, descendants, &descendant_count, PM_MAX_PROCS);

    for (int i = 0; i < descendant_count; i++)
        montauk::kill(descendants[i]);

    montauk::kill(root_pid);
    refresh_state(true);
}

static void cycle_tab(int delta) {
    int next = g_pm.active_tab + delta;
    while (next < 0) next += PM_TAB_COUNT;
    while (next >= PM_TAB_COUNT) next -= PM_TAB_COUNT;
    g_pm.active_tab = next;
    clamp_scrolls();
}

static Rect toolbar_rect() {
    return {0, 0, g_win.width, PM_TOOLBAR_H};
}

static Rect refresh_button_rect() {
    int btn_h = 26;
    int btn_y = (PM_TOOLBAR_H - btn_h) / 2;
    return {8, btn_y, 82, btn_h};
}

static Rect kill_button_rect() {
    int btn_h = 26;
    int btn_y = (PM_TOOLBAR_H - btn_h) / 2;
    return {98, btn_y, 110, btn_h};
}

static Rect tab_bar_rect() {
    return {0, PM_TOOLBAR_H, g_win.width, PM_TAB_H};
}

static bool mouse_in_rect(const Rect& rect) {
    return rect.contains(g_pm.mouse_x, g_pm.mouse_y);
}

static void build_process_columns(mtk::TableColumn* cols) {
    int col_pid = 12;
    int col_ppid = 64;
    int col_name = 124;
    int col_heap = g_win.width - 150;
    int col_state = g_win.width - 70;
    cols[0] = {"PID", col_pid, gui_max(col_ppid - col_pid - 8, 0)};
    cols[1] = {"PPID", col_ppid, gui_max(col_name - col_ppid - 10, 0)};
    cols[2] = {"Name", col_name, gui_max(col_heap - col_name - 10, 0)};
    cols[3] = {"Heap", col_heap, gui_max(col_state - col_heap - 8, 0)};
    cols[4] = {"State", col_state, gui_max(g_win.width - col_state - 8, 0)};
}

static void build_window_columns(mtk::TableColumn* cols) {
    int col_id = 12;
    int col_pid = 60;
    int col_title = 118;
    int col_size = g_win.width - 130;
    int col_dirty = g_win.width - 52;
    cols[0] = {"ID", col_id, gui_max(col_pid - col_id - 8, 0)};
    cols[1] = {"PID", col_pid, gui_max(col_title - col_pid - 10, 0)};
    cols[2] = {"Title", col_title, gui_max(col_size - col_title - 10, 0)};
    cols[3] = {"Size", col_size, gui_max(col_dirty - col_size - 8, 0)};
    cols[4] = {"D", col_dirty, gui_max(g_win.width - col_dirty - 8, 0)};
}

static int hovered_process_row() {
    if (g_pm.active_tab != PM_TAB_PROCESSES) return -1;
    return mtk::table_hit_row(process_table_layout(), g_pm.proc_scroll,
                              g_pm.proc_count, g_pm.mouse_x, g_pm.mouse_y);
}

static int hovered_window_row() {
    if (g_pm.active_tab != PM_TAB_WINDOWS) return -1;
    return mtk::table_hit_row(window_table_layout(), g_pm.win_scroll,
                              g_pm.win_count, g_pm.mouse_x, g_pm.mouse_y);
}

static void draw_text_fit(Canvas& c, int x, int y,
                          const char* text, int max_w, Color color) {
    if (!text || !text[0] || max_w <= 4) return;
    if (text_width(text) <= max_w) {
        c.text(x, y, text, color);
        return;
    }

    const char* ellipsis = "...";
    int ell_w = text_width(ellipsis);
    if (ell_w >= max_w) return;

    char buf[96];
    int out = 0;
    while (text[out] && out < (int)sizeof(buf) - 4) {
        buf[out] = text[out];
        buf[out + 1] = '\0';
        if (text_width(buf) + ell_w > max_w)
            break;
        out++;
    }

    if (out <= 0) return;
    buf[out] = '.';
    buf[out + 1] = '.';
    buf[out + 2] = '.';
    buf[out + 3] = '\0';
    c.text(x, y, buf, color);
}

static void render_toolbar(Canvas& c, const mtk::Theme& theme, int fh) {
    Rect bar = toolbar_rect();
    c.fill_rect(bar.x, bar.y, bar.w, bar.h, theme.surface);
    c.hline(bar.x, bar.y + bar.h - 1, bar.w, theme.border);

    Rect refresh_rect = refresh_button_rect();
    Rect kill_rect = kill_button_rect();
    mtk::draw_button(c, refresh_rect, "Refresh", mtk::BUTTON_TONAL,
                     mtk::widget_state(false, mouse_in_rect(refresh_rect)), theme);
    mtk::draw_button(c, kill_rect, "End Process", mtk::BUTTON_DANGER,
                     mtk::widget_state(false, mouse_in_rect(kill_rect), can_kill_selected()), theme);

    char status[96];
    if (g_pm.active_tab == PM_TAB_PERFORMANCE) {
        snprintf(status, sizeof(status), "CPU %d%%, Memory %d%%",
                 g_pm.cpu_percent, g_pm.mem_percent);
    } else if (g_pm.active_tab == PM_TAB_PROCESSES) {
        snprintf(status, sizeof(status), "%d shown, %d live",
                 g_pm.proc_count, live_process_count());
    } else {
        snprintf(status, sizeof(status), "%d windows", g_pm.win_count);
    }

    int status_w = text_width(status);
    c.text(g_win.width - status_w - 12, (PM_TOOLBAR_H - fh) / 2, status, theme.text);
}

static void render_tabs(Canvas& c, const mtk::Theme& theme) {
    mtk::draw_tab_bar(c, tab_bar_rect(), g_tab_labels, PM_TAB_COUNT, g_pm.active_tab, theme);
}

static void draw_process_row(Canvas& c, void* userdata, int row_index,
                             const Rect& row_rect, int text_y,
                             const mtk::TableColumn* cols, int col_count,
                             const mtk::Theme& theme, const mtk::TableStyle& style) {
    (void)userdata;
    (void)col_count;
    (void)style;

    char buf[32];

    Rect pid_cell = mtk::table_cell_rect(row_rect, cols[0]);
    snprintf(buf, sizeof(buf), "%d", (int)g_pm.procs[row_index].pid);
    c.text(pid_cell.x, text_y, buf, theme.text);

    Rect ppid_cell = mtk::table_cell_rect(row_rect, cols[1]);
    snprintf(buf, sizeof(buf), "%d", (int)g_pm.procs[row_index].parentPid);
    c.text(ppid_cell.x, text_y, buf, theme.text);

    Rect name_cell = mtk::table_cell_rect(row_rect, cols[2]);
    draw_text_fit(c, name_cell.x, text_y, g_pm.procs[row_index].name,
                  name_cell.w, theme.text);

    Rect heap_cell = mtk::table_cell_rect(row_rect, cols[3]);
    format_size(buf, g_pm.procs[row_index].heapUsed);
    c.text(heap_cell.x, text_y, buf, theme.text);

    Rect state_cell = mtk::table_cell_rect(row_rect, cols[4]);
    Color state_color;
    const char* state = proc_state_label(g_pm.procs[row_index].state, &state_color);
    c.text(state_cell.x, text_y, state, state_color);
}

static void render_processes(Canvas& c, const mtk::Theme& theme, int fh) {
    (void)fh;
    mtk::TableLayout layout = process_table_layout();
    mtk::TableColumn cols[5];
    build_process_columns(cols);

    mtk::TableStyle style = mtk::make_table_style(theme);
    style.row_selected_bg = colors::MENU_HOVER;
    style.row_hover_bg = mtk::mix(theme.window_bg, theme.accent, 12);

    mtk::draw_table(c, layout, cols, 5, g_pm.proc_count, g_pm.proc_scroll,
                    g_pm.selected, hovered_process_row(),
                    theme, style, draw_process_row, nullptr);
}

static void draw_window_row(Canvas& c, void* userdata, int row_index,
                            const Rect& row_rect, int text_y,
                            const mtk::TableColumn* cols, int col_count,
                            const mtk::Theme& theme, const mtk::TableStyle& style) {
    (void)userdata;
    (void)col_count;
    (void)style;

    char buf[64];

    Rect id_cell = mtk::table_cell_rect(row_rect, cols[0]);
    snprintf(buf, sizeof(buf), "%d", (int)g_pm.windows[row_index].id);
    c.text(id_cell.x, text_y, buf, theme.text);

    Rect pid_cell = mtk::table_cell_rect(row_rect, cols[1]);
    snprintf(buf, sizeof(buf), "%d", (int)g_pm.windows[row_index].ownerPid);
    c.text(pid_cell.x, text_y, buf, theme.text);

    Rect title_cell = mtk::table_cell_rect(row_rect, cols[2]);
    draw_text_fit(c, title_cell.x, text_y, g_pm.windows[row_index].title,
                  title_cell.w, theme.text);

    Rect size_cell = mtk::table_cell_rect(row_rect, cols[3]);
    snprintf(buf, sizeof(buf), "%dx%d",
             (int)g_pm.windows[row_index].width, (int)g_pm.windows[row_index].height);
    c.text(size_cell.x, text_y, buf, theme.text);

    Rect dirty_cell = mtk::table_cell_rect(row_rect, cols[4]);
    c.text(dirty_cell.x, text_y, g_pm.windows[row_index].dirty ? "Y" : "N",
           g_pm.windows[row_index].dirty ? PM_WARNING : theme.text_subtle);
}

static void render_windows(Canvas& c, const mtk::Theme& theme, int fh) {
    (void)fh;
    mtk::TableLayout layout = window_table_layout();
    mtk::TableColumn cols[5];
    build_window_columns(cols);

    mtk::TableStyle style = mtk::make_table_style(theme);
    style.row_selected_bg = colors::MENU_HOVER;
    style.row_hover_bg = mtk::mix(theme.window_bg, theme.accent, 12);

    mtk::draw_table(c, layout, cols, 5, g_pm.win_count, g_pm.win_scroll,
                    g_pm.selected_window, hovered_window_row(),
                    theme, style, draw_window_row, nullptr);
}

static uint64_t scale_with_headroom(uint64_t observed, uint64_t floor) {
    uint64_t scale = observed > floor ? observed : floor;
    if (scale == 0) return 1;
    return scale + scale / 4;
}

static void format_memory_value(char* buf, int max) {
    char used[24];
    char total[24];
    format_size(used, g_pm.mem.usedBytes);
    format_size(total, g_pm.mem.totalBytes);
    snprintf(buf, max, "%s / %s", used, total);
}

static void render_graph(Canvas& c,
                         const Rect& rect,
                         const mtk::GraphHistory& history,
                         uint64_t max_value,
                         const char* title,
                         const char* value,
                         Color line,
                         const mtk::Theme& theme) {
    mtk::GraphStyle style = mtk::make_graph_style(theme, line);
    style.background = theme.window_bg;
    style.plot_bg = Color::from_rgb(0xFA, 0xFA, 0xFA);
    style.grid = mtk::mix(style.plot_bg, line, 16);
    style.fill = mtk::lighten(line, 225);
    mtk::draw_line_graph(c, rect, history, max_value, title, value, theme, style);
}

static void render_performance(Canvas& c, const mtk::Theme& theme, int fh) {
    (void)fh;

    Rect body = {0, content_top(), g_win.width, gui_max(g_win.height - content_top(), 0)};
    int margin = 12;
    int gap = 10;
    int col_w = gui_max((body.w - margin * 2 - gap) / 2, 80);
    int row_h = gui_max((body.h - margin * 2 - gap * 2) / 3, 72);
    int x0 = body.x + margin;
    int x1 = x0 + col_w + gap;
    int y0 = body.y + margin;
    int y1 = y0 + row_h + gap;
    int y2 = y1 + row_h + gap;

    Rect cpu_rect = {x0, y0, col_w, row_h};
    Rect mem_rect = {x1, y0, col_w, row_h};
    Rect proc_rect = {x0, y1, col_w, row_h};
    Rect heap_rect = {x1, y1, col_w, row_h};
    Rect win_rect = {x0, y2, body.w - margin * 2, row_h};

    char cpu_value[32];
    snprintf(cpu_value, sizeof(cpu_value), "%d%%", g_pm.cpu_percent);
    render_graph(c, cpu_rect, g_pm.cpu_history, 100, "CPU", cpu_value,
                 PM_INFO, theme);

    char mem_value[64];
    format_memory_value(mem_value, sizeof(mem_value));
    render_graph(c, mem_rect, g_pm.mem_history,
                 g_pm.mem.totalBytes > 0 ? g_pm.mem.totalBytes : 1,
                 "Memory", mem_value, PM_SUCCESS, theme);

    char proc_value[48];
    snprintf(proc_value, sizeof(proc_value), "%d live", live_process_count());
    render_graph(c, proc_rect, g_pm.proc_history,
                 g_pm.sys_info.maxProcesses > 0 ? g_pm.sys_info.maxProcesses : PM_MAX_PROCS,
                 "Processes", proc_value, Color::from_rgb(0x7B, 0x3E, 0xB8), theme);

    char heap_value[32];
    format_size(heap_value, g_pm.total_process_heap);
    uint64_t heap_scale = scale_with_headroom(mtk::graph_history_max(g_pm.heap_history),
                                              1024ULL * 1024ULL);
    render_graph(c, heap_rect, g_pm.heap_history, heap_scale,
                 "Process Heap", heap_value, PM_WARNING, theme);

    char win_value[40];
    snprintf(win_value, sizeof(win_value), "%d windows", g_pm.win_count);
    render_graph(c, win_rect, g_pm.win_history, PM_MAX_WINDOWS,
                 "Windows", win_value, Color::from_rgb(0x00, 0x88, 0x88), theme);
}

static void render() {
    mtk::StandaloneHost host(&g_win);
    Canvas c = host.canvas();
    mtk::Theme theme = pm_theme();
    c.fill(theme.window_bg);

    int fh = system_font_height();
    render_toolbar(c, theme, fh);
    render_tabs(c, theme);

    switch (g_pm.active_tab) {
    case PM_TAB_PERFORMANCE:
        render_performance(c, theme, fh);
        break;
    case PM_TAB_PROCESSES:
        render_processes(c, theme, fh);
        break;
    case PM_TAB_WINDOWS:
        render_windows(c, theme, fh);
        break;
    }
}

static bool handle_toolbar_click(int mx, int my) {
    if (refresh_button_rect().contains(mx, my)) {
        refresh_state(true);
        return true;
    }
    if (kill_button_rect().contains(mx, my)) {
        kill_selected();
        return true;
    }
    return false;
}

static bool handle_tab_click(int mx, int my) {
    int tab = mtk::hit_tab_bar(tab_bar_rect(), PM_TAB_COUNT, mx, my);
    if (tab >= 0) {
        g_pm.active_tab = tab;
        return true;
    }
    return false;
}

static bool handle_process_click(int mx, int my) {
    int index = mtk::table_hit_row(process_table_layout(), g_pm.proc_scroll,
                                   g_pm.proc_count, mx, my);
    g_pm.selected = index;
    return true;
}

static bool handle_window_click(int mx, int my) {
    int index = mtk::table_hit_row(window_table_layout(), g_pm.win_scroll,
                                   g_pm.win_count, mx, my);
    g_pm.selected_window = index;
    return true;
}

static bool handle_mouse(const Montauk::WinEvent& ev) {
    bool refresh_hover_before = mouse_in_rect(refresh_button_rect());
    bool kill_hover_before = mouse_in_rect(kill_button_rect());

    g_pm.mouse_x = ev.mouse.x;
    g_pm.mouse_y = ev.mouse.y;

    bool redraw = false;
    if (refresh_hover_before != mouse_in_rect(refresh_button_rect()) ||
        kill_hover_before != mouse_in_rect(kill_button_rect())) {
        redraw = true;
    }

    if (ev.mouse.scroll != 0) {
        if (g_pm.active_tab == PM_TAB_PROCESSES) {
            g_pm.proc_scroll -= ev.mouse.scroll * 3;
            clamp_scrolls();
            return true;
        }
        if (g_pm.active_tab == PM_TAB_WINDOWS) {
            g_pm.win_scroll -= ev.mouse.scroll * 3;
            clamp_scrolls();
            return true;
        }
    }

    bool left_pressed = (ev.mouse.buttons & 1) && !(ev.mouse.prev_buttons & 1);
    if (!left_pressed)
        return redraw;

    int mx = ev.mouse.x;
    int my = ev.mouse.y;

    if (toolbar_rect().contains(mx, my))
        return handle_toolbar_click(mx, my) || redraw;
    if (tab_bar_rect().contains(mx, my))
        return handle_tab_click(mx, my) || redraw;

    if (g_pm.active_tab == PM_TAB_PROCESSES)
        return handle_process_click(mx, my) || redraw;
    if (g_pm.active_tab == PM_TAB_WINDOWS)
        return handle_window_click(mx, my) || redraw;
    return redraw;
}

static bool handle_key(const Montauk::KeyEvent& key) {
    if (!key.pressed)
        return false;

    if (key.scancode == 0x0F) {
        cycle_tab(key.shift ? -1 : 1);
        return true;
    }

    if (key.scancode == 0x4B) {
        cycle_tab(-1);
        return true;
    }

    if (key.scancode == 0x4D) {
        cycle_tab(1);
        return true;
    }

    if (key.scancode == 0x53) {
        if (can_kill_selected()) {
            kill_selected();
            return true;
        }
    }

    if (key.scancode == 0x48) {
        if (g_pm.active_tab == PM_TAB_PROCESSES) {
            if (g_pm.selected > 0) g_pm.selected--;
            else if (g_pm.proc_count > 0) g_pm.selected = 0;
            ensure_process_selection_visible();
            return true;
        }
        if (g_pm.active_tab == PM_TAB_WINDOWS) {
            if (g_pm.selected_window > 0) g_pm.selected_window--;
            else if (g_pm.win_count > 0) g_pm.selected_window = 0;
            ensure_window_selection_visible();
            return true;
        }
    }

    if (key.scancode == 0x50) {
        if (g_pm.active_tab == PM_TAB_PROCESSES) {
            if (g_pm.selected < g_pm.proc_count - 1) g_pm.selected++;
            else if (g_pm.selected < 0 && g_pm.proc_count > 0) g_pm.selected = 0;
            ensure_process_selection_visible();
            return true;
        }
        if (g_pm.active_tab == PM_TAB_WINDOWS) {
            if (g_pm.selected_window < g_pm.win_count - 1) g_pm.selected_window++;
            else if (g_pm.selected_window < 0 && g_pm.win_count > 0) g_pm.selected_window = 0;
            ensure_window_selection_visible();
            return true;
        }
    }

    return false;
}

extern "C" void _start() {
    if (!fonts::init())
        montauk::exit(1);

    if (!g_win.create("Processes", INIT_W, INIT_H))
        montauk::exit(1);

    montauk::memset(&g_pm, 0, sizeof(g_pm));
    init_graph_histories();
    refresh_static_info();
    g_pm.selected = -1;
    g_pm.selected_window = -1;
    g_pm.active_tab = PM_TAB_PROCESSES;
    g_pm.mouse_x = -1;
    g_pm.mouse_y = -1;

    refresh_state(true);
    render();
    g_win.present();

    while (!g_win.closed) {
        bool redraw = refresh_state(false);

        Montauk::WinEvent ev;
        int r = g_win.poll(&ev);
        if (r < 0) break;

        if (r == 0) {
            if (redraw) {
                render();
                g_win.present();
            }
            montauk::sleep_ms(16);
            continue;
        }

        if (ev.type == 3)
            break;

        if (ev.type == 1) redraw |= handle_mouse(ev);
        else if (ev.type == 0) redraw |= handle_key(ev.key);
        else if (ev.type == 2 || ev.type == 4) redraw = true;

        if (redraw) {
            render();
            g_win.present();
        }
    }

    g_win.destroy();
    montauk::exit(0);
}