#include "common.h"

#include <errno.h>
#include <math.h>
#include <stdio.h>
#include <string.h>

#include <xcb/xcb.h>
#include <xcb/xcb_event.h>
#include <xcb/xcb_keysyms.h>
#if HAVE_XCB_ICCCM
# include <xcb/xcb_icccm.h>
#endif

#define HAVE_STRUCT_TIMESPEC 1

#include "paths.h"
#include "safe_fifo.h"
#include "thread.h"

#if HAVE_XCB_ICCCM
typedef struct atoms_t
{
    xcb_atom_t WM_DELETE_WINDOW;
    xcb_atom_t WM_PROTOCOLS;
} atoms_t;
#endif

typedef enum message_type_t
{
    MSG_QUIT,
    MSG_DRAW,
    MSG_SWAP,
    MSG_CLEAR
} message_type_t;

typedef struct message_t
{
    message_type_t type;
} message_t;

static message_t quit_message = { MSG_QUIT };
static message_t draw_message = { MSG_DRAW };
static message_t swap_message = { MSG_SWAP };
static message_t clear_message = { MSG_CLEAR };

typedef struct time_target_t time_target_t;

typedef bool (* timer_callback_t)(void *data);

struct time_target_t
{
    time_target_t *next;
    struct timespec target;
    unsigned long interval_ms;
    void *data;
    timer_callback_t callback;
};

typedef struct main_t
{
    xcb_connection_t *conn;
    xcb_window_t wnd;
    xcb_gcontext_t gc;
    xcb_font_t font;
#if HAVE_XCB_ICCCM
    atoms_t atoms;
#endif
    safe_fifo_t *queue;
    const char *state;
    paths_t *paths;
    time_target_t *first_timer;
    bool save_queued;
    bool redraw_queued;
    unsigned int width, height;
    uint32_t background[2], foreground[2];

    /* State */
    bool working;
    time_t last_time;
    unsigned long total_min;
} main_t;

static const char DEFAULT_STATE[] = "timer.state";

static const char FONT_NAME[] = "7x13";

static const unsigned long REDRAW_INTERVAL_MS = 36 * 1000;

static bool handle_arguments(main_t *m, int argc, char **argv, int *exitcode);
static void draw(main_t *m);
static void *run_xcb(void *arg);
static bool load_state(main_t *m);
static bool save_state(main_t *m);
static void default_state(main_t *m);
static void swap(main_t *m);
static void clear(main_t *m);
static void queue_save(main_t *m);
static void add_timer(main_t *m, unsigned long interval_ms,
                      timer_callback_t callback, void *data);
static void insert_timer(main_t *m, time_target_t *target);
static void run_timer(main_t *m);
static bool redraw(void *arg);
static int timeval_cmp(const struct timespec* x, const struct timespec* y);

int main(int argc, char **argv)
{
    main_t m;
    xcb_screen_iterator_t iter;
    xcb_screen_t *screen;
    int screen_index;
    uint32_t mask, values[2];
    xcb_void_cookie_t cookie[10];
    size_t cookies = 0;
    int exitcode;
    bool quit = false;
    memset(&m, 0, sizeof(m));

    if (!handle_arguments(&m, argc, argv, &exitcode))
    {
        return exitcode;
    }

    m.paths = paths_new();
    if (!m.paths)
    {
        fputs("Unable to allocate memory.\n", stderr);
        return EXIT_FAILURE;
    }

    if (!load_state(&m))
    {
        fputs("Error loading old state.\n", stderr);
        paths_unref(m.paths);
        return EXIT_FAILURE;
    }

    m.conn = xcb_connect(NULL, &screen_index);
    if (!m.conn)
    {
        fputs("Unable to connect to X11 display.\n", stderr);
        paths_unref(m.paths);
        return EXIT_FAILURE;
    }

#if HAVE_XCB_ICCCM
    {
        xcb_intern_atom_cookie_t cookie[2];
        xcb_intern_atom_reply_t *reply;
        xcb_generic_error_t *err;

        cookie[0] = xcb_intern_atom(m.conn, 0, strlen("WM_DELETE_WINDOW"),
                                    "WM_DELETE_WINDOW");;
        cookie[1] = xcb_intern_atom(m.conn, 0, strlen("WM_PROTOCOLS"),
                                    "WM_PROTOCOLS");;
        reply = xcb_intern_atom_reply(m.conn, cookie[0], &err);
        if (!reply)
        {
            fprintf(stderr, "ICCCM init atoms failed\n");
            xcb_disconnect(m.conn);
            paths_unref(m.paths);
            return EXIT_FAILURE;
        }
        m.atoms.WM_DELETE_WINDOW = reply->atom;
        free(reply);
        reply = xcb_intern_atom_reply(m.conn, cookie[1], &err);
        if (!reply)
        {
            fprintf(stderr, "ICCCM init atoms failed\n");
            xcb_disconnect(m.conn);
            paths_unref(m.paths);
            return EXIT_FAILURE;
        }
        m.atoms.WM_PROTOCOLS = reply->atom;
        free(reply);
    }
#endif

    iter = xcb_setup_roots_iterator(xcb_get_setup(m.conn));
    while (screen_index-- > 0)
    {
        xcb_screen_next(&iter);
    }

    screen = iter.data;

    {
        xcb_alloc_color_cookie_t req[4];
        xcb_alloc_color_reply_t* rep;
        /* background, not working */
        req[0] = xcb_alloc_color(m.conn, screen->default_colormap,
                                 0x8000, 0x8000, 0x8000);
        /* background, working */
        req[1] = xcb_alloc_color(m.conn, screen->default_colormap,
                                 0x8000, 0xffff, 0x8000);
        /* foreground, not working */
        req[2] = xcb_alloc_color(m.conn, screen->default_colormap,
                                 0, 0, 0);
        /* foreground, working */
        req[3] = xcb_alloc_color(m.conn, screen->default_colormap,
                                 0, 0, 0);
        rep = xcb_alloc_color_reply(m.conn, req[0], 0);
        m.background[0] = rep ? rep->pixel : screen->white_pixel;
        free(rep);
        rep = xcb_alloc_color_reply(m.conn, req[1], 0);
        m.background[1] = rep ? rep->pixel : screen->white_pixel;
        free(rep);
        rep = xcb_alloc_color_reply(m.conn, req[2], 0);
        m.foreground[0] = rep ? rep->pixel : screen->black_pixel;
        free(rep);
        rep = xcb_alloc_color_reply(m.conn, req[3], 0);
        m.foreground[1] = rep ? rep->pixel : screen->black_pixel;
        free(rep);
    }

    m.font = xcb_generate_id(m.conn);
    cookie[cookies++] = xcb_open_font_checked(m.conn, m.font,
                                              sizeof(FONT_NAME) /
                                              sizeof(FONT_NAME[0]),
                                              FONT_NAME);

    mask = XCB_CW_BACK_PIXEL | XCB_CW_EVENT_MASK;
    values[0] = screen->black_pixel;
    values[1] = XCB_EVENT_MASK_EXPOSURE | XCB_EVENT_MASK_BUTTON_PRESS |
        XCB_EVENT_MASK_KEY_RELEASE;

    m.width = 100;
    m.height = 50;

    m.wnd = xcb_generate_id(m.conn);
    cookie[cookies++] = xcb_create_window_checked(m.conn, XCB_COPY_FROM_PARENT,
                                                  m.wnd, screen->root,
                                                  0, 0, m.width, m.height, 0,
                                                  XCB_WINDOW_CLASS_INPUT_OUTPUT,
                                                  screen->root_visual,
                                                  mask, values);

    m.gc = xcb_generate_id(m.conn);
    mask = XCB_GC_FONT;
    values[0] = m.font;
    cookie[cookies++] = xcb_create_gc_checked(m.conn, m.gc, m.wnd,
                                              mask, values);

    cookie[cookies++] = xcb_map_window_checked(m.conn, m.wnd);

#if HAVE_XCB_ICCCM
    {
        xcb_atom_t protocols[1];
        protocols[0] = m.atoms.WM_DELETE_WINDOW;

        xcb_icccm_set_wm_protocols(m.conn, m.wnd, m.atoms.WM_PROTOCOLS,
                                   1, protocols);
        xcb_icccm_set_wm_name(m.conn, m.wnd, XCB_ATOM_STRING, 8, 5, "timer");
        xcb_icccm_set_wm_class(m.conn, m.wnd, 8, "jk.timer");
    }
#endif

    while (cookies--)
    {
        xcb_generic_error_t *error = xcb_request_check(m.conn, cookie[cookies]);
        if (error)
        {
            fprintf(stderr, "Error: %d\n", error->error_code);
            xcb_disconnect(m.conn);
            paths_unref(m.paths);
            return EXIT_FAILURE;
        }
    }

    xcb_flush(m.conn);

    m.queue = safe_fifo_new();

    thread_new(run_xcb, &m);

    if (m.working)
    {
        add_timer(&m, REDRAW_INTERVAL_MS, redraw, &m);
        m.redraw_queued = true;
    }

    while (!quit)
    {
        message_t *msg;
        if (m.first_timer)
        {
            struct timespec now;
            thread_abstime(&now, 0);
            if (timeval_cmp(&now, &m.first_timer->target) >= 0)
            {
                run_timer(&m);
                msg = safe_fifo_trypop(m.queue);
            }
            else
            {
                msg = safe_fifo_timedpop(m.queue, &m.first_timer->target);
            }
        }
        else
        {
            msg = safe_fifo_pop(m.queue);
        }
        if (msg)
        {
            switch (msg->type)
            {
            case MSG_QUIT:
                quit = true;
                break;
            case MSG_DRAW:
                draw(&m);
                break;
            case MSG_SWAP:
                swap(&m);
                break;
            case MSG_CLEAR:
                clear(&m);
                break;
            }
        }
    }

    if (m.save_queued)
    {
        save_state(&m);
    }

    xcb_close_font(m.conn, m.font);
    xcb_free_gc(m.conn, m.gc);
    xcb_destroy_window(m.conn, m.wnd);

    xcb_disconnect(m.conn);
    while (m.first_timer)
    {
        time_target_t *next = m.first_timer->next;
        free(m.first_timer);
        m.first_timer = next;
    }
    paths_unref(m.paths);
    safe_fifo_unref(m.queue);

    return EXIT_SUCCESS;
}

static void print_usage(void)
{
    fputs("Usage: timer [OPTION]...\n", stdout);
    fputs("Timer is a timekeeping tool.\n", stdout);
    fputs("\n", stdout);
    fputs("Options:\n", stdout);
    fputs("  -state FILE      load state from FILE instead of default\n", stdout);
    fputs("  -help            display this information and exit\n", stdout);
    fputs("  -version         display version and exit\n", stdout);
}

static void print_version(void)
{
    fputs("timer version " VERSION " written by Joel Klinghed\n", stdout);
}

bool handle_arguments(main_t *m, int argc, char **argv, int *exitcode)
{
    bool usage = false, version = false, error = false;
    int a;
    for (a = 1; a < argc; a++)
    {
        if (argv[a][0] == '-')
        {
            if (strcmp(argv[a] + 1, "help") == 0)
            {
                usage = true;
                break;
            }
            else if (strcmp(argv[a] + 1, "version") == 0)
            {
                version = true;
                break;
            }
            else if (strcmp(argv[a] + 1, "state") == 0)
            {
                if (++a == argc)
                {
                    error = true;
                    fputs("Option `state` expects an argument.\n", stderr);
                    break;
                }
                if (m->state)
                {
                    error = true;
                    fputs("Option `state` given twice.\n", stderr);
                    break;
                }
                m->state = argv[a];
            }
            else
            {
                error = true;
                fprintf(stderr, "Unknown option: %s\n", argv[a] + 1);
                break;
            }
        }
        else
        {
            break;
        }
    }
    if (!error && a < argc)
    {
        fputs("Too many arguments given.\n", stderr);
        error = true;
    }
    if (usage)
    {
        print_usage();
        *exitcode = error ? EXIT_FAILURE : EXIT_SUCCESS;
        return false;
    }
    if (error)
    {
        fputs("Try `timer -help` for usage.\n", stderr);
        *exitcode = EXIT_FAILURE;
        return false;
    }
    if (version)
    {
        print_version();
        *exitcode = EXIT_SUCCESS;
        return false;
    }
    return true;
}

void draw(main_t *m)
{
    xcb_rectangle_t r;
    xcb_char2b_t *tmp;
    uint32_t values[2];
    char text[50];
    int x, y, i, len;
    xcb_query_text_extents_cookie_t cookie;
    xcb_query_text_extents_reply_t *reply;

    if (m->working)
    {
        double diff = difftime(time(NULL), m->last_time);
        diff /= 60.0 * 60.0;

        len = snprintf(text, sizeof(text), "%.2f (%.2f)", diff,
                       (double)m->total_min / 60.0 + diff);
    }
    else
    {
        len = snprintf(text, sizeof(text), "(%.2f)",
                       (double)m->total_min / 60.0);
    }
    if (len < 0 || len == sizeof(text))
    {
        return;
    }
    tmp = malloc(len * sizeof(xcb_char2b_t));
    for (i = 0; i < len; i++)
    {
        tmp[i].byte1 = 0;
        tmp[i].byte2 = text[i];
    }

    cookie = xcb_query_text_extents(m->conn, m->font, len, tmp);

    r.x = 0;
    r.y = 0;
    r.width = m->width;
    r.height = m->height;

    values[0] = m->background[m->working ? 1 : 0];
    xcb_change_gc(m->conn, m->gc, XCB_GC_FOREGROUND, values);
    xcb_poly_fill_rectangle(m->conn, m->wnd, m->gc, 1, &r);

    values[0] = m->foreground[m->working ? 1 : 0];
    values[1] = m->background[m->working ? 1 : 0];
    xcb_change_gc(m->conn, m->gc, XCB_GC_FOREGROUND | XCB_GC_BACKGROUND, values);

    x = 0;
    y = m->height / 2;

    reply = xcb_query_text_extents_reply(m->conn, cookie, NULL);
    if (reply)
    {
        if (reply->overall_width < m->width)
        {
            x = (m->width - reply->overall_width) / 2;
        }
        else
        {
            x = 0;
        }
        y += reply->font_ascent / 2;
        free(reply);
    }

    xcb_image_text_16(m->conn, len, m->wnd, m->gc, x, y, tmp);

    xcb_flush(m->conn);

    free(tmp);
}

static void send_message(main_t *m, message_t* msg)
{
    safe_fifo_push(m->queue, msg);
}

void *run_xcb(void *arg)
{
    main_t *m = arg;
    xcb_key_symbols_t *syms;

    syms = xcb_key_symbols_alloc(m->conn);

    for (;;)
    {
        bool done = false;
        xcb_generic_event_t *event = xcb_wait_for_event(m->conn);
        if (!event || xcb_connection_has_error(m->conn))
        {
            free(event);
            break;
        }
        switch (XCB_EVENT_RESPONSE_TYPE(event))
        {
        case XCB_EXPOSE:
        {
            xcb_expose_event_t *e = (xcb_expose_event_t*)event;
            if (e->count == 0)
            {
                send_message(m, &draw_message);
            }
            break;
        }
#if HAVE_XCB_ICCCM
        case XCB_CLIENT_MESSAGE:
        {
            xcb_client_message_event_t *e = (xcb_client_message_event_t*)event;
            if (e->type == m->atoms.WM_PROTOCOLS && e->format == 32 &&
                e->data.data32[0] == m->atoms.WM_DELETE_WINDOW)
            {
                done = true;
            }
            break;
        }
#endif
        case XCB_BUTTON_PRESS:
        {
            xcb_button_press_event_t *e = (xcb_button_press_event_t*)event;
            if (e->detail == 1)
            {
                send_message(m, &swap_message);
            }
            break;
        }
        case XCB_KEY_RELEASE:
        {
            xcb_key_press_event_t *e = (xcb_key_press_event_t*)event;
            xcb_keysym_t sym = xcb_key_press_lookup_keysym(syms, e, 0);
            if (sym == ' ')
            {
                send_message(m, &swap_message);
            }
            else if (sym == 'r' && (e->state & XCB_MOD_MASK_CONTROL))
            {
                send_message(m, &clear_message);
            }
            break;
        }
        case XCB_MAPPING_NOTIFY:
        {
            xcb_mapping_notify_event_t *e = (xcb_mapping_notify_event_t*)event;
            xcb_refresh_keyboard_mapping(syms, e);
            break;
        }
        }
        free(event);
        if (done)
        {
            break;
        }
    }
    xcb_key_symbols_free(syms);
    send_message(m, &quit_message);
    return NULL;
}

bool load_state(main_t *m)
{
    FILE *fh;
    char *tmp, *line;
    const char *fname;
    char buf[1024];
    char *end;
    long l;
    unsigned long ul;
    struct tm tm;
    if (m->state)
    {
        fname = m->state;
        tmp = NULL;
    }
    else
    {
        const char *dir = paths_user_dir(m->paths, PATHS_DATA);
        size_t dlen = strlen(dir);
        tmp = malloc(dlen + 1 + sizeof(DEFAULT_STATE));
        if (!tmp)
        {
            fputs("Out of memory\n", stderr);
            return false;
        }
        memcpy(tmp, dir, dlen);
        tmp[dlen] = '/';
        memcpy(tmp + dlen + 1, DEFAULT_STATE, sizeof(DEFAULT_STATE));
        fname = tmp;
    }
    fh = fopen(fname, "rb");
    if (!fh)
    {
        if (errno == ENOENT)
        {
            default_state(m);
            free(tmp);
            return true;
        }
        fprintf(stderr, "Error loading state from %s: %s\n", fname,
                strerror(errno));
        free(tmp);
        return false;
    }

    line = fgets(buf, sizeof(buf), fh);
    if (!line)
    {
        fprintf(stderr, "Error reading state from %s: %s\n", fname,
                strerror(errno));
        free(tmp);
        return false;
    }

    fclose(fh);

    end = NULL;
    l = strtol(line, &end, 10);
    if ((l != -1 && l != 1) || !end || *end != '|')
    {
        fprintf(stderr, "Invalid data in state %s: %s\n", fname,
                strerror(errno));
        free(tmp);
        return false;
    }

    line = end + 1;
    end = NULL;
    ul = strtoul(line, &end, 10);
    if (!end || *end != '|')
    {
        fprintf(stderr, "Invalid data in state %s: %s\n", fname,
                strerror(errno));
        free(tmp);
        return false;
    }

    end = strptime(end + 1, "%Y-%m-%d %H:%M:%S", &tm);
    if (!end)
    {
        fprintf(stderr, "Invalid data in state %s: %s\n", fname,
                strerror(errno));
        free(tmp);
        return false;
    }

    m->working = l == 1;
    m->last_time = timegm(&tm);
    m->total_min = ul;

    free(tmp);
    return true;
}

bool save_state(main_t *m)
{
    paths_file_t *file = paths_write(m->paths, PATHS_DATA,
                                     m->state ? m->state : DEFAULT_STATE,
                                     PATHS_CREATE | PATHS_TRUNCATE,
                                     0600);
    char buf[1024];
    size_t len2;
    int pos, len;
    m->save_queued = false;

    if (!file)
    {
        fprintf(stderr, "Failed to save state: %s\n", strerror(errno));
        return false;
    }

    len = snprintf(buf, sizeof(buf), "%d|%lu|",
                   m->working ? 1 : -1, m->total_min);
    if (len < 0 || len == sizeof(buf))
    {
        fprintf(stderr, "Failed to save state: %s\n", strerror(errno));
        paths_file_abort(file);
        return false;
    }
    len2 = strftime(buf + len, sizeof(buf) - len, "%Y-%m-%d %H:%M:%S",
                   gmtime(&m->last_time));
    if (len2 == 0 || len2 == sizeof(buf) - len)
    {
        fprintf(stderr, "Failed to save state: %s\n", strerror(errno));
        paths_file_abort(file);
        return false;
    }
    len += len2;
    pos = 0;
    while (pos < len)
    {
        ssize_t got = paths_file_write(file, buf + pos, len - pos);
        if (got <= 0)
        {
            fprintf(stderr, "Failed to save state: %s\n", strerror(errno));
            paths_file_abort(file);
            return false;
        }
        pos += got;
    }

    if (paths_file_close(file))
    {
        fprintf(stderr, "Failed to finish saving state: %s\n", strerror(errno));
        paths_file_abort(file);
        return false;
    }
    return true;
}

void default_state(main_t *m)
{
    m->working = false;
    m->last_time = time(NULL);
    m->total_min = 0;
}

void swap(main_t *m)
{
    if (m->working)
    {
        double diff = difftime(time(NULL), m->last_time);
        m->total_min += round(diff / 60.0);
        m->working = false;
    }
    else
    {
        m->working = true;
        if (!m->redraw_queued)
        {
            add_timer(m, REDRAW_INTERVAL_MS, redraw, m);
            m->redraw_queued = true;
        }
    }

    m->last_time = time(NULL);

    draw(m);
    queue_save(m);
}

void clear(main_t *m)
{
    if (m->working)
    {
        return;
    }

    default_state(m);
    draw(m);
    queue_save(m);
}

static bool do_save(void *arg)
{
    main_t *m = arg;
    assert(m->save_queued);
    save_state(m);
    return false;
}

void queue_save(main_t *m)
{
    if (m->save_queued)
    {
        return;
    }
    add_timer(m, 5000, do_save, m);
    m->save_queued = true;
}

void add_timer(main_t *m, unsigned long interval_ms,
               timer_callback_t callback, void *data)
{
    time_target_t* tgt = calloc(1, sizeof(time_target_t));
    assert(interval_ms > 0);
    tgt->interval_ms = interval_ms;
    tgt->callback = callback;
    tgt->data = data;
    thread_abstime(&tgt->target, interval_ms);
    insert_timer(m, tgt);
}

void insert_timer(main_t* m, time_target_t *target)
{
    time_target_t *cur, *last;
    assert(target->next == NULL);
    if (!m->first_timer)
    {
        m->first_timer = target;
        return;
    }
    last = NULL;
    cur = m->first_timer;
    while (cur)
    {
        if (timeval_cmp(&cur->target, &target->target) > 0)
        {
            target->next = cur;
            if (last == NULL)
            {
                m->first_timer = target;
                return;
            }
            else
            {
                break;
            }
        }
        last = cur;
        cur = last->next;
    }
    last->next = target;
}

void run_timer(main_t *m)
{
    time_target_t *target = m->first_timer;
    m->first_timer = target->next;
    target->next = NULL;
    if (target->callback(target->data))
    {
        thread_abstime(&target->target, target->interval_ms);
        insert_timer(m, target);
    }
    else
    {
        free(target);
    }
}

bool redraw(void *arg)
{
    main_t* m = arg;
    assert(m->redraw_queued);
    if (m->working)
    {
        draw(m);
        return true;
    }
    m->redraw_queued = false;
    return false;
}

int timeval_cmp(const struct timespec* x, const struct timespec* y)
{
    assert(x && y);
    if (x->tv_sec < y->tv_sec)
    {
        return -1;
    }
    else if (x->tv_sec == y->tv_sec)
    {
        if (x->tv_nsec < y->tv_nsec)
        {
            return -1;
        }
        else if (x->tv_nsec == y->tv_nsec)
        {
            return 0;
        }
    }

    return 1;
}