#include "backend.h"
#include "loop.h"

#include <errno.h>
#include <stdlib.h>
#include <string.h>

static const struct yasl_backend_ops *backend_ops(enum yasl_backend backend)
{
    switch (backend) {
#if YASL_HAS_WAYLAND
    case YASL_BACKEND_WAYLAND: return &yasl_wayland_backend;
#endif
#if YASL_HAS_X11
    case YASL_BACKEND_X11: return &yasl_x11_backend;
#endif
#if YASL_HAS_COCOA
    case YASL_BACKEND_COCOA: return &yasl_cocoa_backend;
#endif
    default: return NULL;
    }
}

static struct yasl_display *open_backend(enum yasl_backend backend,
        struct yasl_loop *loop, const struct yasl_display_spec *spec)
{
    const struct yasl_backend_ops *ops = backend_ops(backend);
    if (!ops) {
        errno = ENOSYS;
        return NULL;
    }
    errno = 0;
    struct yasl_display *d = ops->display_open(loop, spec);
    if (!d && !errno) errno = ENODEV;
    return d;
}

struct yasl_display *yasl_display_open(struct yasl_loop *loop,
        const struct yasl_display_spec *spec)
{
    enum yasl_backend backend = spec ? spec->backend : YASL_BACKEND_AUTO;
    if (backend < YASL_BACKEND_AUTO || backend > YASL_BACKEND_COCOA) {
        errno = EINVAL;
        return NULL;
    }
    if (backend != YASL_BACKEND_AUTO)
        return open_backend(backend, loop, spec);
#if YASL_HAS_COCOA
    return open_backend(YASL_BACKEND_COCOA, loop, spec);
#else
    const char *session = getenv("XDG_SESSION_TYPE");
    bool wayland = getenv("WAYLAND_DISPLAY") || getenv("WAYLAND_SOCKET") ||
                   (session && strcmp(session, "wayland") == 0);
    enum yasl_backend first = wayland ? YASL_BACKEND_WAYLAND : YASL_BACKEND_X11;
    enum yasl_backend second = wayland ? YASL_BACKEND_X11 : YASL_BACKEND_WAYLAND;
    struct yasl_display *d = NULL;
    if (backend_ops(first)) d = open_backend(first, loop, spec);
    if (!d && backend_ops(second)) d = open_backend(second, loop, spec);
    return d;
#endif
}

enum yasl_backend yasl_display_backend(const struct yasl_display *d)
{
    return d ? d->ops->type : YASL_BACKEND_AUTO;
}

void yasl_display_close(struct yasl_display *d)
{
    if (!d || !d->ops->display_close)
        return;
    d->ops->display_close(d);
}

uint32_t yasl_display_caps(const struct yasl_display *d)
{
    if (!d || !d->ops->display_caps)
        return 0;
    return d->ops->display_caps(d);
}

int yasl_display_dispatch(struct yasl_display *d, int timeout_ms)
{
    if (!d) {
        errno = EINVAL;
        return -1;
    }
    if (!d->ops->display_dispatch_timeout) {
        errno = ENOTSUP;
        return -1;
    }
    errno = 0;
    int result = d->ops->display_dispatch_timeout(d, timeout_ms);
    if (result < 0 && !errno) errno = EIO;
    return result;
}

void yasl_display_flush(struct yasl_display *d)
{
    if (!d || !d->ops->display_flush)
        return;
    d->ops->display_flush(d);
}

int yasl_display_modifiers(const struct yasl_display *d)
{
    if (!d || !d->ops->display_modifiers)
        return 0;
    return d->ops->display_modifiers(d);
}

void yasl_display_copy(struct yasl_display *d, enum yasl_selection sel, const char *text)
{
    if (!d || !d->ops->display_copy || !text ||
        (sel != YASL_CLIPBOARD && sel != YASL_PRIMARY) ||
        (sel == YASL_PRIMARY && !(yasl_display_caps(d) & YASL_CAP_PRIMARY_SELECTION)))
        return;
    d->ops->display_copy(d, sel, text);
}

void yasl_display_paste(struct yasl_display *d, enum yasl_selection sel, struct yasl_surface *target)
{
    if (!d || !d->ops->display_paste ||
        (sel != YASL_CLIPBOARD && sel != YASL_PRIMARY) ||
        (sel == YASL_PRIMARY && !(yasl_display_caps(d) & YASL_CAP_PRIMARY_SELECTION)))
        return;
    if (!target || target->display != d)
        return;
    d->ops->display_paste(d, sel, target);
}

bool yasl_display_drag_start(struct yasl_display *d, struct yasl_surface *origin, const struct yasl_drag_image *image, const struct yasl_drag_listener *l, void *ud)
{
    if (!d || !d->ops->display_drag_start)
        return 0;
    if (!origin || origin->display != d)
        return false;
    if (image && (!image->pixels || image->size.x <= 0 || image->size.y <= 0 ||
        image->size.x > 32767 || image->size.y > 32767 ||
        (int64_t)image->size.x * image->size.y * 4 > INT32_MAX))
        return false;
    const struct yasl_drag_listener empty = {0};
    return d->ops->display_drag_start(d, origin, image, l ? l : &empty, ud);
}

void yasl_display_drag_cancel(struct yasl_display *d)
{
    if (!d || !d->ops->display_drag_cancel)
        return;
    d->ops->display_drag_cancel(d);
}

struct yasl_surface *yasl_create_toplevel(struct yasl_display *d,
        const struct yasl_surface_spec *spec, void *graphics_device)
{
    if (!d || !d->ops->surface_create_toplevel || !spec ||
        spec->size.x <= 0 || spec->size.y <= 0 ||
        spec->size.x > 32767 || spec->size.y > 32767 ||
        (int64_t)spec->size.x * spec->size.y * 4 > INT32_MAX) {
        errno = EINVAL;
        return NULL;
    }
    if (graphics_device && !(yasl_display_caps(d) & YASL_CAP_NATIVE_GRAPHICS)) {
        errno = ENOTSUP;
        return NULL;
    }
    errno = 0;
    struct yasl_surface *s = d->ops->surface_create_toplevel(d, spec, graphics_device);
    if (!s && !errno) errno = ENODEV;
    return s;
}

struct yasl_surface *yasl_surface_create_toplevel(struct yasl_display *d,
        const struct yasl_surface_spec *spec)
{
    return yasl_create_toplevel(d, spec, NULL);
}

static bool popup_spec_valid(const struct yasl_popup_spec *spec)
{
    return spec && spec->size.x > 0 && spec->size.y > 0 &&
        spec->size.x <= 32767 && spec->size.y <= 32767 &&
        (int64_t)spec->size.x * spec->size.y * 4 <= INT32_MAX &&
        spec->anchor.width >= 0 && spec->anchor.height >= 0 &&
        spec->content_offset.x >= 0 && spec->content_offset.y >= 0 &&
        spec->content_size.x >= 0 && spec->content_size.y >= 0 &&
        (int64_t)spec->content_offset.x + spec->content_size.x <= spec->size.x &&
        (int64_t)spec->content_offset.y + spec->content_size.y <= spec->size.y;
}

struct yasl_surface *yasl_surface_create_popup(struct yasl_surface *parent, const struct yasl_popup_spec *spec)
{
    if (!parent || !popup_spec_valid(spec)) {
        errno = EINVAL;
        return NULL;
    }
    if (!(yasl_display_caps(parent->display) & YASL_CAP_POPUPS) ||
        !parent->display->ops->surface_create_popup) {
        errno = ENOTSUP;
        return NULL;
    }
    errno = 0;
    struct yasl_surface *s = parent->display->ops->surface_create_popup(parent, spec);
    if (!s && !errno) errno = ENODEV;
    return s;
}

bool yasl_surface_popup_reposition(struct yasl_surface *popup, const struct yasl_popup_spec *spec)
{
    if (!popup || !popup_spec_valid(spec)) {
        errno = EINVAL;
        return false;
    }
    if (!(yasl_display_caps(popup->display) & YASL_CAP_POPUPS) ||
        !popup->display->ops->surface_popup_reposition) {
        errno = ENOTSUP;
        return false;
    }
    errno = 0;
    bool result = popup->display->ops->surface_popup_reposition(popup, spec);
    if (!result && !errno) errno = ENODEV;
    return result;
}

void yasl_surface_destroy(struct yasl_surface *s)
{
    if (!s || !s->display->ops->surface_destroy)
        return;
    yasl_surface_clear_timers(s);
    input_queue_clear(&s->input);
    s->display->ops->surface_destroy(s);
}

struct yasl_display *yasl_surface_display(const struct yasl_surface *s)
{
    return s ? s->display : NULL;
}

void yasl_surface_set_callbacks(struct yasl_surface *s, const struct yasl_surface_cbs *cbs, void *ud)
{
    if (!s)
        return;
    s->callbacks = cbs ? *cbs : (struct yasl_surface_cbs){0};
    s->ud = ud;
    if (s->display && s->display->ops && s->display->ops->surface_set_callbacks)
        s->display->ops->surface_set_callbacks(s, cbs, ud);
}

void yasl_surface_set_title(struct yasl_surface *s, const char *title)
{
    if (!s || !s->display->ops->surface_set_title)
        return;
    s->display->ops->surface_set_title(s, title);
}

void yasl_surface_schedule_redraw(struct yasl_surface *s)
{
    if (!s || !s->display->ops->surface_schedule_redraw)
        return;
    s->display->ops->surface_schedule_redraw(s);
}

bool yasl_surface_present(struct yasl_surface *s, const struct yasl_framebuffer *fb, const struct yasl_damage_list *damage)
{
    if (!s || !s->display->ops->surface_present || !fb || !damage ||
        !fb->generation || fb->generation != s->frame_generation ||
        fb->size.x <= 0 || fb->size.y <= 0 ||
        damage->n < -1 || damage->n > YASL_DAMAGE_MAX)
        return false;
    struct yasl_damage_list clipped;
    clipped.n = damage->n;
    if (damage->n < 0) {
        clipped.bounds = damage->bounds;
    } else {
        clipped.n = 0;
        clipped.bounds = (struct yasl_rect2i){0};
        for (int i = 0; i < damage->n; i++) {
            struct yasl_rect2i r = damage->rects[i];
            if (r.width < 0 || r.height < 0) return false;
            int64_t right = (int64_t)r.x + r.width;
            int64_t bottom = (int64_t)r.y + r.height;
            int64_t x = r.x > 0 ? r.x : 0, y = r.y > 0 ? r.y : 0;
            if (right > fb->size.x) right = fb->size.x;
            if (bottom > fb->size.y) bottom = fb->size.y;
            if (right > x && bottom > y)
                clipped.rects[clipped.n++] = (struct yasl_rect2i){
                    (int)x, (int)y, (int)(right - x), (int)(bottom - y),
                };
        }
    }
    return s->display->ops->surface_present(s, fb, &clipped);
}

bool yasl_surface_input_poll(struct yasl_surface *s, struct yasl_input_event *ev)
{
    if (!s || !ev)
        return false;
    if (s->display && s->display->ops && s->display->ops->surface_input_poll)
        return s->display->ops->surface_input_poll(s, ev);
    return input_queue_pop(&s->input, ev);
}

struct yasl_geometry yasl_surface_geometry(const struct yasl_surface *s)
{
    if (!s)
        return (struct yasl_geometry){.scale_120 = YASL_SCALE_UNIT};
    if (s->scale_120)
        return (struct yasl_geometry){s->size, s->scale_120};
    if (s->display && s->display->ops && s->display->ops->surface_geometry)
        return s->display->ops->surface_geometry(s);
    return (struct yasl_geometry){s->size, YASL_SCALE_UNIT};
}

uint32_t yasl_surface_state(const struct yasl_surface *s)
{
    if (!s || !s->display->ops->surface_state)
        return 0;
    return s->display->ops->surface_state(s);
}

struct yasl_timing yasl_surface_timing(const struct yasl_surface *s)
{
    if (!s)
        return (struct yasl_timing){0};
    if (s->display && s->display->ops && s->display->ops->surface_timing)
        return s->display->ops->surface_timing(s);
    struct yasl_timing t = {
        .refresh_ns = s->clock.refresh_ns,
        .last_present_ns = s->clock.last_present_ns,
        .next_present_ns = yasl_clock_next_present_ns(&s->clock),
        .frames_skipped = s->frames_skipped,
        .source = s->clock.source,
    };
    yasl_clock_resize_stats(&s->clock, &t.resize);
    return t;
}

uint64_t yasl_surface_frame_time_ns(struct yasl_surface *s, uint64_t now)
{
    if (!s)
        return 0;
    if (s->display && s->display->ops && s->display->ops->surface_frame_time_ns)
        return s->display->ops->surface_frame_time_ns(s, now);
    return yasl_clock_frame_timestamp_ns(&s->clock, now);
}

void yasl_surface_set_cursor(struct yasl_surface *s, enum yasl_cursor cursor)
{
    if (!s || !s->display->ops->surface_set_cursor)
        return;
    s->display->ops->surface_set_cursor(s, cursor);
}

void yasl_surface_set_background_color(struct yasl_surface *s, uint32_t bg)
{
    if (!s || !s->display->ops->surface_set_background_color)
        return;
    s->display->ops->surface_set_background_color(s, bg);
}

const char *yasl_surface_ime_preedit(const struct yasl_surface *s)
{
    if (!s || !s->display->ops->surface_ime_preedit)
        return 0;
    return s->display->ops->surface_ime_preedit(s);
}

bool yasl_surface_ime_preedit_cursor(const struct yasl_surface *s, int *begin, int *end)
{
    if (!s || !begin || !end || !s->display->ops->surface_ime_preedit_cursor)
        return 0;
    return s->display->ops->surface_ime_preedit_cursor(s, begin, end);
}

void yasl_surface_set_ime_caret(struct yasl_surface *s, struct yasl_rect2i caret)
{
    if (!s || !s->display->ops->surface_set_ime_caret)
        return;
    s->display->ops->surface_set_ime_caret(s, caret);
}

bool yasl_surface_start_interactive_move(struct yasl_surface *s)
{
    if (!s || !s->display->ops->surface_start_interactive_move)
        return 0;
    return s->display->ops->surface_start_interactive_move(s);
}

bool yasl_surface_start_interactive_resize(struct yasl_surface *s, enum yasl_resize_edge edge)
{
    if (!s || !s->display->ops->surface_start_interactive_resize ||
        (edge != YASL_EDGE_TOP && edge != YASL_EDGE_BOTTOM &&
         edge != YASL_EDGE_LEFT && edge != YASL_EDGE_RIGHT &&
         edge != YASL_EDGE_TOP_LEFT && edge != YASL_EDGE_TOP_RIGHT &&
         edge != YASL_EDGE_BOTTOM_LEFT && edge != YASL_EDGE_BOTTOM_RIGHT))
        return 0;
    return s->display->ops->surface_start_interactive_resize(s, edge);
}

bool yasl_surface_show_window_menu(struct yasl_surface *s, struct yasl_vector2i pos)
{
    if (!s || !s->display->ops->surface_show_window_menu)
        return 0;
    return s->display->ops->surface_show_window_menu(s, pos);
}

bool yasl_surface_drag_carry(struct yasl_surface *s, struct yasl_vector2i offset)
{
    if (!s || !s->display->ops->surface_drag_carry)
        return 0;
    return s->display->ops->surface_drag_carry(s, offset);
}

bool yasl_surface_place_under_pointer(struct yasl_surface *s, struct yasl_vector2i at)
{
    if (!s || !s->display->ops->surface_place_under_pointer)
        return 0;
    return s->display->ops->surface_place_under_pointer(s, at);
}

void yasl_surface_clear_timers(struct yasl_surface *s)
{
    if (!s || !s->timers) return;
    struct yasl_loop *loop = s->display ? s->display->loop : NULL;
    for (int i = 0; i < s->timer_count; i++) {
        if (loop && s->timers[i]) {
            yasl_loop_del_timer(loop, s->timers[i]);
        }
    }
    free(s->timers);
    s->timers = NULL;
    s->timer_count = 0;
    s->timer_capacity = 0;
}

yasl_timer_id yasl_surface_add_timer(struct yasl_surface *s, uint64_t interval_ns,
                                     yasl_timer_cb cb, void *ud)
{
    if (!s || !s->display || !s->display->loop || !cb || interval_ns == 0)
        return 0;

    yasl_timer_id id = yasl_loop_add_timer(s->display->loop, interval_ns, cb, ud);
    if (!id) return 0;

    /* A one-shot timer retires itself in the loop. Drop retired ids before
     * the list grows, so the list holds only armed timers. */
    if (s->timer_count >= s->timer_capacity) {
        int kept = 0;
        for (int i = 0; i < s->timer_count; i++)
            if (yasl_loop_timer_armed(s->display->loop, s->timers[i]))
                s->timers[kept++] = s->timers[i];
        s->timer_count = kept;
    }
    if (s->timer_count >= s->timer_capacity) {
        int new_cap = s->timer_capacity ? s->timer_capacity * 2 : 4;
        yasl_timer_id *nt = realloc(s->timers, (size_t)new_cap * sizeof(*nt));
        if (!nt) {
            yasl_loop_del_timer(s->display->loop, id);
            return 0;
        }
        s->timers = nt;
        s->timer_capacity = new_cap;
    }
    s->timers[s->timer_count++] = id;
    return id;
}

bool yasl_surface_del_timer(struct yasl_surface *s, yasl_timer_id id)
{
    if (!s || id == 0) return false;
    for (int i = 0; i < s->timer_count; i++) {
        if (s->timers[i] == id) {
            s->timers[i] = s->timers[--s->timer_count];
            return s->display && yasl_loop_del_timer(s->display->loop, id);
        }
    }
    return false;
}

struct yasl_loop *yasl_display_loop(struct yasl_display *d)
{
    return d ? d->loop : NULL;
}