"""
layout/page/page_layout.py
---------------------------
頁面主體 layout 組裝。
只負責把各子模組的產出組合成最終的 dmc.Container，
不含資料邏輯，也不直接定義 callback。

公開 API：
    make_test_page(json_source, *, top_offset, show_src) → dmc.Container
"""

from __future__ import annotations
from typing import Any

import traceback

from dash import html, dcc
import dash_mantine_components as dmc

from ..renderer.renderer import render_doc

try:
    from ..renderer.renderer import install_callbacks_once
except Exception:
    install_callbacks_once = None

from ..toc import make_toc
from .loader import load_json, build_toc_titles
from .sections import (
    split_blocks_into_sections,
    get_section_blocks,
    make_section_control,
)
from .page_callbacks import register_page_callbacks


# ---------------------------------------------------------------------------
# 回到頂端按鈕樣式（獨立常數，方便日後調整）
# ---------------------------------------------------------------------------
_BACK_TO_TOP_STYLE: dict[str, Any] = {
    "position": "fixed",
    "right": "24px",
    "bottom": "24px",
    "width": "46px",
    "height": "46px",
    "borderRadius": "999px",
    "border": "none",
    "textDecoration": "none",
    "display": "flex",
    "alignItems": "center",
    "justifyContent": "center",
    "background": "rgba(0, 0, 0, 0.35)",
    "color": "white",
    "fontSize": "22px",
    "cursor": "pointer",
    "zIndex": 999,
    "backdropFilter": "blur(4px)",
    "boxShadow": "0 4px 12px rgba(0,0,0,0.18)",
}

# TOC 欄固定定位樣式
def _toc_fixed_style(top_offset: int) -> dict[str, Any]:
    return {
        "position": "sticky",
        "top": f"{top_offset + 12}px",
        "maxHeight": f"calc(100vh - {top_offset + 32}px)",
        "overflowY": "auto",
        "overflowX": "hidden",
        "paddingRight": "4px",
        "alignSelf": "flex-start",
    }


# ---------------------------------------------------------------------------
# 主要組裝函式
# ---------------------------------------------------------------------------

def make_test_page(
    json_source: Any,
    *,
    top_offset: int = 90,
    show_src: bool = True,
) -> dmc.Container:
    """
    組裝完整的頁面 Container。

    json_source：可傳入檔案路徑（str/Path）、已解析的 dict 或 list。
    top_offset： 頁首高度（px），用於 TOC 固定定位與 scroll offset。
    show_src：   保留參數（尚未使用），預留供未來顯示原始 JSON 用。
    """
    # 1. 確保 dashTest callbacks 已掛載
    if callable(install_callbacks_once):
        try:
            install_callbacks_once()
        except Exception:
            pass

    # 2. 確保頁面 callbacks 已掛載
    register_page_callbacks()

    # 3. 載入資料
    data = load_json(json_source)
    blocks   = data.get("blocks", [])
    sections = data.get("sections", []) or []
    raw_toc  = data.get("toc", []) or []

    # 4. 若 JSON 未提供 sections，自動按 H2 切割
    if not sections:
        sections = split_blocks_into_sections(blocks)

    # 5. 決定初始 section
    default_section_id = sections[0].get("id") if sections else None
    current_blocks = get_section_blocks(sections, default_section_id) if sections else blocks

    # 6. 渲染初始內容
    try:
        content = render_doc(current_blocks)
    except Exception as e:
        content = dmc.Alert(
            f"render_doc 發生錯誤：{e}\n\n{traceback.format_exc(limit=2)}",
            title="渲染失敗",
            color="red",
            variant="filled",
        )

    # 7. Section 控制列
    section_control = make_section_control(sections, default_section_id)

    # 8. 左欄：Store + 控制列 + 內容
    left_children: list[Any] = [
        dcc.Store(id="page-sections-store",        data=sections),
        dcc.Store(id="page-raw-toc-store",         data=raw_toc),
        dcc.Store(id="page-active-section-store",  data=default_section_id),
    ]
    if section_control is not None:
        left_children.append(section_control)
    left_children.append(html.Div(content, id="section-content-wrapper"))

    left_area = dmc.Stack(left_children, gap="md", style={"minWidth": 0})

    # 9. TOC（僅當有標題時才產生）
    toc_titles    = build_toc_titles(current_blocks, raw_toc)
    has_toc       = bool(toc_titles)
    toc_component = (
        make_toc(
            titles=toc_titles,
            top_offset=top_offset,
            col_span={"xs": 0, "sm": 0, "md": 3, "lg": 3, "xl": 3},
            visible_from="md",
        )
        if has_toc
        else None
    )

    # 10. Grid 欄位配置
    main_span = {"base": 12, "md": 9 if has_toc else 12}
    toc_span  = {"base": 12, "md": 3} if has_toc else {"base": 12, "md": 0}
    toc_style = _toc_fixed_style(top_offset) if has_toc else {}

    cols = [
        dmc.GridCol(left_area, id="main-content-col", span=main_span),
        dmc.GridCol(
            html.Div(
                id="section-toc-wrapper",
                children=toc_component,
                style=toc_style,
            ),
            id="toc-col",
            span=toc_span,
            className="toc-col-wrapper",
            style={"display": "block" if has_toc else "none"},
        ),
    ]

    # compat：空 Grid 讓 Dash 的 pattern-matching callback 不出錯
    grid   = dmc.Grid(cols, gutter="xl")
    compat = dmc.Grid(id="Grid", style={"display": "none"})

    return dmc.Container(
        [
            html.Div(id="page-top-anchor"),
            dmc.Stack([grid, compat], gap="md"),
            html.A(
                "↑",
                href="#page-top-anchor",
                title="回到最上方",
                id="back-to-top-btn",
                style=_BACK_TO_TOP_STYLE,
            ),
        ],
        fluid=True,
        style={"overflow": "visible"},
    )