"""HTML 预览生成服务"""
from html import escape
from typing import Any, Dict, List


PAGE_STYLE = (
    "width:794px;min-height:1123px;margin:0 auto;background:#fff;"
    "padding:72px 64px;box-sizing:border-box;color:#1a1d24;"
    "font-family:-apple-system,BlinkMacSystemFont,'PingFang SC','Microsoft YaHei',sans-serif;"
    "font-size:14px;line-height:1.8;"
)

HEADING_STYLE = (
    "font-size:16px;font-weight:700;text-align:center;margin:24px 0 14px;"
    "padding-bottom:6px;border-bottom:2px solid #1a1d24;"
)

PARAGRAPH_STYLE = "text-indent:2em;margin:8px 0;line-height:1.8;text-align:justify;"

TABLE_STYLE = "width:100%;border-collapse:collapse;margin:14px 0;font-size:13px;"
TH_STYLE = "padding:7px 10px;border:1px solid #d8dbe2;background:#f0f1f3;text-align:left;font-weight:600;"
TD_STYLE = "padding:7px 10px;border:1px solid #d8dbe2;text-align:left;min-height:24px;"


def generate_preview_html(blocks: List[Dict[str, Any]]) -> str:
    """
    将 block 列表转为带 data-block-id 的 HTML 预览字符串。
    每个元素都会带上 data-block-id 属性供前端点击交互。
    """
    html_parts = [f'<div class="doc-preview-content" style="{PAGE_STYLE}">']

    for block in blocks:
        block_id = block.get("block_id", "")
        block_type = block.get("type") or block.get("block_type", "")
        text = block.get("text") or block.get("text_preview") or ""

        if block_type == "heading":
            html = render_heading(block_id, text)
        elif block_type == "table":
            html = render_table(block)
        else:
            html = render_paragraph(block_id, text)

        html_parts.append(html)

    html_parts.append('</div>')
    return "\n".join(html_parts)


def render_heading(block_id: str, text: str) -> str:
    return f'<h2 data-block-id="{escape(block_id)}" style="{HEADING_STYLE}">{escape(text)}</h2>'


def render_paragraph(block_id: str, text: str) -> str:
    return f'<p data-block-id="{escape(block_id)}" style="{PARAGRAPH_STYLE}">{escape(text)}</p>'


def render_table(block: Dict[str, Any]) -> str:
    block_id = escape(block.get("block_id", ""))
    headers = [escape(str(header)) for header in block.get("headers", []) if str(header).strip()]
    rows = int(block.get("rows") or block.get("table_rows") or 1)
    cols = int(block.get("cols") or block.get("table_cols") or max(len(headers), 1))
    cols = max(cols, len(headers), 1)
    body_rows = max(rows - 1, 1)

    if not headers:
        text = block.get("text") or block.get("text_preview") or "表格"
        headers = [escape(str(text))] + ["" for _ in range(cols - 1)]

    header_html = "".join(f'<th style="{TH_STYLE}">{header}</th>' for header in headers[:cols])
    if len(headers) < cols:
        header_html += "".join(f'<th style="{TH_STYLE}"></th>' for _ in range(cols - len(headers)))

    row_html = "".join(f'<td style="{TD_STYLE}"></td>' for _ in range(cols))
    body_html = "\n".join(f"<tr>{row_html}</tr>" for _ in range(body_rows))

    return (
        f'<table data-block-id="{block_id}" style="{TABLE_STYLE}">'
        f"<thead><tr>{header_html}</tr></thead>"
        f"<tbody>{body_html}</tbody>"
        "</table>"
    )