from pathlib import Path

import gradio as gr

from gesture_logic import FIRST, LAST, NEXT, PREV, NONE, infer_gesture_command
from hand_tracker import detect_hand
from state import ImageState


ASSETS_DIR = Path("assets")


APP_CSS = """
#app-shell {
    max-width: 1280px;
    margin: 0 auto;
}

.app-heading h1 {
    font-size: 26px;
    line-height: 1.2;
    margin-bottom: 4px;
}

.app-heading p {
    color: #4b5563;
    margin-top: 0;
}

.preview-card {
    border: 1px solid #e5e7eb;
    border-radius: 8px;
    background: #ffffff;
    padding: 12px;
}

.preview-title {
    font-weight: 700;
    margin: 0 0 8px;
}

.preview-image {
    height: min(46vw, 430px);
    min-height: 280px;
    overflow: hidden;
}

.preview-image img,
.preview-image video {
    width: 100% !important;
    height: 100% !important;
    object-fit: contain !important;
}

.preview-image .icon-wrap,
.preview-image .empty,
.preview-image .label-wrap {
    display: none !important;
}

#status-box textarea {
    font-size: 16px;
    font-weight: 600;
}

.command-row button {
    min-height: 44px;
}

@media (max-width: 900px) {
    .preview-image {
        height: 320px;
    }
}
"""


def build_status(command: str, index: int, total: int) -> str:
    if total == 0:
        return f"Command: {command} | Index: 0/0 (no images in assets/)"
    return f"Command: {command} | Index: {index + 1}/{total}"


def apply_command(command: str, current_index: int, webcam_frame=None):
    image_state = ImageState(str(ASSETS_DIR))
    total = len(image_state.image_paths)
    if total > 0:
        if current_index is None:
            image_state.index = 0
        else:
            image_state.index = max(0, min(int(current_index), total - 1))

    # Placeholder call to keep the future hand-tracking interface in place.
    _ = detect_hand(webcam_frame)

    if command == NEXT:
        image_state.next_image()
    elif command == PREV:
        image_state.prev_image()
    elif command == FIRST:
        image_state.first_image()
    elif command == LAST:
        image_state.last_image()

    current_image = image_state.get_current_image()
    total = len(image_state.image_paths)
    status = build_status(command, image_state.index, total)
    return current_image, status, image_state.index


def on_prev(current_index: int):
    return apply_command(PREV, current_index, None)


def on_next(current_index: int):
    return apply_command(NEXT, current_index, None)


def on_first(current_index: int):
    return apply_command(FIRST, current_index, None)


def on_last(current_index: int):
    return apply_command(LAST, current_index, None)


def on_webcam_frame(webcam_frame, current_index: int):
    hand_data = detect_hand(webcam_frame)
    command = infer_gesture_command(hand_data)
    return apply_command(command, current_index, webcam_frame)


def build_demo():
    initial_state = ImageState(str(ASSETS_DIR))
    initial_image = initial_state.get_current_image()
    initial_total = len(initial_state.image_paths)
    initial_status = build_status(NONE, initial_state.index, initial_total)

    with gr.Blocks(title="手勢影像播放器", elem_id="app-shell") as demo:
        gr.Markdown(
            "# 手勢影像播放器\n使用按鈕或單手手勢切換圖片。",
            elem_classes="app-heading",
        )

        with gr.Row():
            with gr.Column(scale=1, elem_classes="preview-card"):
                gr.Markdown("網路攝影機", elem_classes="preview-title")
                webcam_input = gr.Image(
                    sources=["webcam"],
                    type="numpy",
                    streaming=True,
                    show_label=False,
                    height=420,
                    elem_classes="preview-image",
                    placeholder="",
                )
            with gr.Column(scale=1, elem_classes="preview-card"):
                gr.Markdown("目前圖片", elem_classes="preview-title")
                current_image = gr.Image(
                    value=initial_image,
                    type="numpy",
                    show_label=False,
                    height=420,
                    elem_classes="preview-image",
                    buttons=[],
                    placeholder="",
                )

        status_text = gr.Textbox(
            value=initial_status,
            label="狀態",
            interactive=False,
            elem_id="status-box",
        )
        state_holder = gr.State(initial_state.index)

        with gr.Row(elem_classes="command-row"):
            btn_prev = gr.Button("PREV")
            btn_next = gr.Button("NEXT")
            btn_first = gr.Button("FIRST")
            btn_last = gr.Button("LAST")

        btn_prev.click(
            fn=on_prev,
            inputs=[state_holder],
            outputs=[current_image, status_text, state_holder],
        )
        btn_next.click(
            fn=on_next,
            inputs=[state_holder],
            outputs=[current_image, status_text, state_holder],
        )
        btn_first.click(
            fn=on_first,
            inputs=[state_holder],
            outputs=[current_image, status_text, state_holder],
        )
        btn_last.click(
            fn=on_last,
            inputs=[state_holder],
            outputs=[current_image, status_text, state_holder],
        )
        webcam_input.stream(
            fn=on_webcam_frame,
            inputs=[webcam_input, state_holder],
            outputs=[current_image, status_text, state_holder],
        )
        webcam_input.change(
            fn=on_webcam_frame,
            inputs=[webcam_input, state_holder],
            outputs=[current_image, status_text, state_holder],
        )

    return demo


if __name__ == "__main__":
    app = build_demo()
    app.launch(show_error=True, css=APP_CSS)