import streamlit as st
from pathlib import Path
from config import SHARED_ASSETS_DIR 

@st.fragment
def render_tab(project, callbacks):
    """渲染「最終影片合成」標籤頁的 UI。"""
    
    _render_video_management_section(project, callbacks)
    _render_shared_asset_uploader(callbacks)    
    _render_shared_asset_selection(callbacks)

    st.divider()

@st.fragment
def _render_video_management_section(project, callbacks):
    """
    一個私有的輔助函式，用於渲染影片管理的 UI 部分。
    """
    with st.expander("🎬 管理專案影片素材", expanded=False):
        paths = project.paths
        output_dir = paths.get("output", Path("./output")) # 使用 .get 提供預設值
        video_files = []

        if output_dir.exists():
            video_files = sorted(
                [f for f in output_dir.iterdir() if f.suffix.lower() in ['.mp4', '.mov']],
                key=lambda f: f.stat().st_mtime,
                reverse=True
            )

        if not video_files:
            st.info("專案輸出資料夾 (`/output`) 中目前沒有影片檔。")
        else:
            st.markdown("勾選您想要刪除的影片，然後點擊下方的按鈕。")
            
            st.checkbox(
                "全選/取消全選",
                key="select_all_videos",
                on_change=callbacks.toggle_all_video_checkboxes,
                args=(video_files,)
            )

            for video_file in video_files:
                file_size_mb = video_file.stat().st_size / (1024 * 1024)
                st.checkbox(
                    f"**{video_file.name}** ({file_size_mb:.2f} MB)",
                    key=f"delete_cb_{video_file.name}"
                )

            st.button(
                "🟥 確認刪除選取的影片",
                on_click=callbacks.delete_selected_videos,
                use_container_width=True,
                type="primary"
            )

def _render_shared_asset_selection(callbacks):
    """
    一個私有的輔助函式，用於渲染共享素材選擇和上傳的 UI。
    """
    st.subheader("步驟 3.2: 選擇共享影片素材")
    st.subheader("輔助工具")

    
    # 【改動 1】更健壯的檔案列表讀取方式
    try:
        shared_videos = [""] + sorted(
            [f.name for f in SHARED_ASSETS_DIR.glob('*') if f.suffix.lower() in ['.mp4', '.mov']]
        )
    except Exception as e:
        st.error(f"無法讀取共享素材庫 '{SHARED_ASSETS_DIR}': {e}")
        shared_videos = [""]

    with st.container(border=True):
        st.markdown("##### 從共享素材庫中選擇影片")
        c1, c2 = st.columns(2)
        with c1:
            logo_selection = st.selectbox("選擇 Logo 影片:", shared_videos, key="logo_select")
            open_selection = st.selectbox("選擇開場影片:", shared_videos, key="open_select")
        with c2:
            end_selection = st.selectbox("選擇結尾影片:", shared_videos, key="end_select")
        
    st.subheader("步驟 3.2: 執行最終影片合成")
    all_videos_selected = all([logo_selection, open_selection, end_selection])

    if not all_videos_selected:
        st.info("請從上方的下拉選單中選擇所有 Logo、開場和結尾影片以啟用合成按鈕。")


    # 【核心改動】st.button 的呼叫現在非常簡潔
    st.button(
        "🎬 合成最終影片", 
        on_click=callbacks.assemble_final_video, 
        kwargs={
            # 只傳遞 UI 直接相關的、最少的資訊 (檔名)
            "logo_video_name": logo_selection,
            "open_video_name": open_selection,
            "end_video_name": end_selection
        }, 
        disabled=not all_videos_selected,
        use_container_width=True
    )

            
    # 將選擇的結果回傳給主函式
    return logo_selection, open_selection, end_selection

def _render_shared_asset_uploader(callbacks):
    """一個私有的輔助函式，用於渲染共享素材上傳工具。"""
    with st.expander("📂 管理與上傳共享素材", expanded=False):
        st.markdown("這裡上傳的影片將存入 `shared_assets` 公共資料夾，可供所有專案重複使用。")
        
        st.file_uploader(
            "上傳新的影片到共享素材庫",
            type=["mp4", "mov"],
            accept_multiple_files=True,
            label_visibility="collapsed",
            key="shared_video_uploader",
            on_change=callbacks.upload_shared_videos
        )