use axum::extract::{Path, Query};
use axum::http::StatusCode;
use axum::response::Html;
use axum::routing::get;
use axum::{Extension, Json, Router};
use ias_http::shell::{escape_html, html_shell};
use serde_json::{Value, json};
use sqlx::PgPool;

use crate::model::{MailListQuery, MailMessage};
use crate::repository::MailRepository;

type ApiError = (StatusCode, Json<Value>);
type HtmlError = (StatusCode, Html<String>);

#[derive(Clone)]
pub struct MailRouteState {
    pub db: PgPool,
}

impl MailRouteState {
    pub fn new(db: PgPool) -> Self {
        Self { db }
    }
}

pub fn routes<S>(db: PgPool) -> Router<S>
where
    S: Clone + Send + Sync + 'static,
{
    Router::new()
        .route("/v1/mail/messages", get(list_messages))
        .route("/v1/mail/search", get(list_messages))
        .route("/v1/mail/messages/{id}", get(get_message))
        .route("/mail", get(show_mail_list))
        .route("/mail/messages/{id}", get(show_mail_message))
        .layer(Extension(MailRouteState::new(db)))
}

// ── JSON API ─────────────────────────────────────────────

async fn list_messages(
    Extension(state): Extension<MailRouteState>,
    Query(query): Query<MailListQuery>,
) -> Result<Json<Value>, ApiError> {
    let (messages, total, page, per_page) = MailRepository::query_messages(&state.db, &query)
        .await
        .map_err(api_internal_error)?;

    Ok(Json(json!({
        "success": true,
        "page": page,
        "per_page": per_page,
        "total": total,
        "messages": messages,
    })))
}

async fn get_message(
    Extension(state): Extension<MailRouteState>,
    Path(id): Path<i64>,
) -> Result<Json<Value>, ApiError> {
    let message = MailRepository::find(&state.db, id)
        .await
        .map_err(api_internal_error)?
        .ok_or_else(|| api_not_found("邮件记录不存在"))?;

    Ok(Json(json!({
        "success": true,
        "message": message,
    })))
}

// ═══════════════════════════════════════════════════════════
//  HTML 页面：邮件列表（卡片式布局，移动端友好）
// ═══════════════════════════════════════════════════════════

async fn show_mail_list(
    Extension(state): Extension<MailRouteState>,
    Query(query): Query<MailListQuery>,
) -> Result<Html<String>, HtmlError> {
    let (messages, total, page, per_page) = MailRepository::query_messages(&state.db, &query)
        .await
        .map_err(html_internal_error("读取邮件列表失败"))?;

    Ok(Html(render_mail_list(
        &query, &messages, total, page, per_page,
    )))
}

fn render_mail_list(
    query: &MailListQuery,
    messages: &[MailMessage],
    total: i64,
    page: i64,
    per_page: i64,
) -> String {
    let has_filter = query.q.is_some()
        || query.mailbox.is_some()
        || query.source_key.is_some()
        || query.account_id.is_some()
        || query.seen.is_some();

    let subtitle = if has_filter {
        let start = if total == 0 {
            0
        } else {
            (page - 1) * per_page + 1
        };
        let end = ((page - 1) * per_page + messages.len() as i64).min(total);
        format!("筛选结果：共 {total} 封，当前 {start}–{end}")
    } else {
        format!("共 {total} 封邮件")
    };

    let cards: String = if messages.is_empty() {
        r#"<div class="text-center py-16 text-gray-400">
  <div class="text-4xl mb-3">📭</div>
  <p class="text-base">没有匹配的邮件</p>
</div>"#
            .to_string()
    } else {
        messages
            .iter()
            .map(render_mail_card)
            .collect::<Vec<_>>()
            .join("\n")
    };

    let pagination = render_pagination(query, total, page, per_page);
    let filter_html = render_filter_bar(query, has_filter, per_page);

    let body = format!(
        r#"<div class="mb-6">
  <h1 class="text-2xl md:text-3xl font-bold tracking-tight">📧 邮件列表</h1>
  <p class="mt-1.5 text-sm text-gray-500">{subtitle}</p>
</div>

{filter_html}

<div class="flex flex-col gap-3 mb-4">
  {cards}
</div>

{pagination}"#,
        subtitle = subtitle,
        filter_html = filter_html,
        cards = cards,
        pagination = pagination,
    );

    html_shell("邮件列表", &body)
}

// ── 筛选栏 ──────────────────────────────────────────────

fn render_filter_bar(query: &MailListQuery, has_filter: bool, per_page: i64) -> String {
    let q = escape_html(query.q.as_deref().unwrap_or(""));
    let account_id = escape_html(&query.account_id.map(|v| v.to_string()).unwrap_or_default());
    let mailbox = escape_html(query.mailbox.as_deref().unwrap_or(""));
    let source_key = escape_html(query.source_key.as_deref().unwrap_or(""));
    let seen_all_selected = selected_attr(query.seen.is_none());
    let seen_unread_selected = selected_attr(query.seen == Some(false));
    let seen_read_selected = selected_attr(query.seen == Some(true));
    let pp = per_page;

    let clear_btn = if has_filter {
        r#"<a href="/mail" class="inline-flex items-center justify-center px-4 py-2 rounded-lg text-sm font-medium border border-gray-200 bg-white text-gray-600 hover:border-blue-300 hover:text-blue-600 transition">清除</a>"#
    } else {
        ""
    };

    format!(
        r#"<form method="get" action="/mail" class="bg-white rounded-xl border border-gray-200 p-4 md:p-5 mb-5">
  <div class="flex flex-col md:flex-row gap-3">
    <div class="flex-1 min-w-0">
      <input name="q" value="{q}" placeholder="搜索发件人、主题或正文…"
        class="w-full border border-gray-200 rounded-lg px-3.5 py-2.5 text-sm focus:outline-none focus:border-blue-400 focus:ring-2 focus:ring-blue-100 transition placeholder:text-gray-400">
    </div>
    <div class="flex gap-2">
      <input name="account_id" value="{account_id}" placeholder="账户ID" inputmode="numeric"
        class="w-24 md:w-28 border border-gray-200 rounded-lg px-3 py-2.5 text-sm focus:outline-none focus:border-blue-400 focus:ring-2 focus:ring-blue-100 transition placeholder:text-gray-400">
      <input name="mailbox" value="{mailbox}" placeholder="目录"
        class="w-24 md:w-28 border border-gray-200 rounded-lg px-3 py-2.5 text-sm focus:outline-none focus:border-blue-400 focus:ring-2 focus:ring-blue-100 transition placeholder:text-gray-400">
      <input name="source_key" value="{source_key}" placeholder="来源"
        class="w-24 md:w-28 border border-gray-200 rounded-lg px-3 py-2.5 text-sm focus:outline-none focus:border-blue-400 focus:ring-2 focus:ring-blue-100 transition placeholder:text-gray-400">
      <select name="seen"
        class="w-24 md:w-28 border border-gray-200 rounded-lg px-3 py-2.5 text-sm bg-white focus:outline-none focus:border-blue-400 focus:ring-2 focus:ring-blue-100 transition">
        <option value="" {seen_all_selected}>全部</option>
        <option value="false" {seen_unread_selected}>未读</option>
        <option value="true" {seen_read_selected}>已读</option>
      </select>
    </div>
    <input type="hidden" name="per_page" value="{per_page}">
    <div class="flex gap-2">
      <button type="submit" class="inline-flex items-center justify-center px-5 py-2.5 rounded-lg text-sm font-semibold bg-blue-600 text-white hover:bg-blue-700 transition shadow-sm">查询</button>
      {clear_btn}
    </div>
  </div>
</form>"#,
        q = q,
        account_id = account_id,
        mailbox = mailbox,
        source_key = source_key,
        seen_all_selected = seen_all_selected,
        seen_unread_selected = seen_unread_selected,
        seen_read_selected = seen_read_selected,
        per_page = pp,
        clear_btn = clear_btn,
    )
}

fn selected_attr(selected: bool) -> &'static str {
    if selected { "selected" } else { "" }
}

// ── 邮件卡片（替代表格） ────────────────────────────────

fn render_mail_card(msg: &MailMessage) -> String {
    let received = msg
        .received_at
        .as_ref()
        .map(|t| t.format("%m-%d %H:%M").to_string())
        .unwrap_or_else(|| "-".to_string());
    let relative = msg
        .received_at
        .as_ref()
        .map(|t| relative_time(t))
        .unwrap_or_default();
    let subject = if msg.subject.trim().is_empty() {
        "无主题"
    } else {
        &msg.subject
    };
    let preview = truncate(&msg.content_preview, 120);
    let status_badge = mail_status_badge(msg.seen);
    let card_class = if msg.seen {
        "block bg-white rounded-xl border border-gray-200 p-4 md:p-5 hover:border-blue-400 hover:shadow-md transition group"
    } else {
        "block bg-white rounded-xl border border-blue-200 p-4 md:p-5 hover:border-blue-400 hover:shadow-md transition group shadow-sm"
    };

    format!(
        r#"<a href="/mail/messages/{id}" class="{card_class}">
  <div class="flex items-start justify-between gap-3 mb-2">
    <h3 class="text-sm md:text-base font-semibold text-gray-900 group-hover:text-blue-700 leading-snug min-w-0 break-words">{subject}</h3>
    <div class="shrink-0 flex items-center gap-2 pt-0.5">
      {status_badge}
      <span class="text-xs text-gray-400 whitespace-nowrap hidden sm:inline">{received}</span>
    </div>
  </div>
  <div class="flex flex-col sm:flex-row sm:items-center sm:justify-between gap-1.5 mb-2.5">
    <span class="text-sm text-gray-600 truncate">{from}</span>
    <div class="flex items-center gap-1.5">
      <span class="sm:hidden text-xs text-gray-400">{received}</span>
      <span class="text-xs text-gray-400">{relative}</span>
    </div>
  </div>
  {preview_html}
  <div class="flex items-center gap-2 mt-2.5">
    <span class="inline-flex items-center px-2 py-0.5 rounded-md text-[11px] font-medium bg-blue-50 text-blue-600">#{id}</span>
    <span class="inline-flex items-center px-2 py-0.5 rounded-md text-[11px] font-medium bg-gray-100 text-gray-500">{mailbox}</span>
    <span class="inline-flex items-center px-2 py-0.5 rounded-md text-[11px] font-medium bg-gray-100 text-gray-500">{source}</span>
  </div>
</a>"#,
        id = msg.id,
        card_class = card_class,
        subject = escape_html(subject),
        received = escape_html(&received),
        relative = escape_html(&relative),
        status_badge = status_badge,
        from = escape_html(&msg.from_label),
        preview_html = if preview.is_empty() {
            String::new()
        } else {
            format!(
                r#"<p class="text-xs text-gray-400 line-clamp-2 leading-relaxed">{}</p>"#,
                escape_html(&preview)
            )
        },
        mailbox = escape_html(&msg.mailbox),
        source = escape_html(&msg.source_key),
    )
}

fn mail_status_badge(seen: bool) -> &'static str {
    if seen {
        r#"<span class="inline-flex items-center px-2 py-0.5 rounded-md text-[11px] font-medium bg-gray-100 text-gray-500">已读</span>"#
    } else {
        r#"<span class="inline-flex items-center gap-1 px-2 py-0.5 rounded-md text-[11px] font-semibold bg-blue-50 text-blue-700"><span class="w-1.5 h-1.5 rounded-full bg-blue-600"></span>未读</span>"#
    }
}

// ── 分页 ────────────────────────────────────────────────

fn render_pagination(query: &MailListQuery, total: i64, page: i64, per_page: i64) -> String {
    if total == 0 {
        return String::new();
    }
    let last_page = ((total + per_page - 1) / per_page).max(1);

    let prev = if page > 1 {
        format!(
            r#"<a href="{}" class="inline-flex items-center gap-1 px-4 py-2 rounded-lg text-sm font-medium border border-gray-200 bg-white text-blue-600 hover:border-blue-400 hover:bg-blue-50 transition no-underline">‹ 上一页</a>"#,
            escape_html(&mail_list_url(query, page - 1, per_page))
        )
    } else {
        r#"<span class="inline-flex items-center gap-1 px-4 py-2 rounded-lg text-sm border border-gray-200 bg-white text-gray-300 cursor-default">‹ 上一页</span>"#.to_string()
    };

    let next = if page < last_page {
        format!(
            r#"<a href="{}" class="inline-flex items-center gap-1 px-4 py-2 rounded-lg text-sm font-medium border border-gray-200 bg-white text-blue-600 hover:border-blue-400 hover:bg-blue-50 transition no-underline">下一页 ›</a>"#,
            escape_html(&mail_list_url(query, page + 1, per_page))
        )
    } else {
        r#"<span class="inline-flex items-center gap-1 px-4 py-2 rounded-lg text-sm border border-gray-200 bg-white text-gray-300 cursor-default">下一页 ›</span>"#.to_string()
    };

    let nums = render_page_numbers(query, page, last_page, per_page);

    format!(
        r#"<nav class="flex items-center justify-between gap-3 mt-5">
  {prev}
  <div class="hidden sm:flex gap-1 items-center">{nums}</div>
  <span class="sm:hidden text-sm text-gray-400">{page} / {last_page}</span>
  {next}
</nav>"#
    )
}

fn render_page_numbers(query: &MailListQuery, page: i64, last_page: i64, per_page: i64) -> String {
    let start = (page - 2).max(1);
    let end = (page + 2).min(last_page);
    let mut nums = Vec::new();

    if start > 1 {
        nums.push(format!(
            r#"<a href="{}" class="inline-flex items-center justify-center w-8 h-8 rounded-lg text-sm text-blue-600 hover:bg-blue-50 transition no-underline">1</a>"#,
            escape_html(&mail_list_url(query, 1, per_page))
        ));
        if start > 2 {
            nums.push(r#"<span class="text-gray-300 px-1 text-sm">…</span>"#.to_string());
        }
    }

    for p in start..=end {
        if p == page {
            nums.push(format!(r#"<span class="inline-flex items-center justify-center w-8 h-8 rounded-lg text-sm font-semibold bg-blue-600 text-white">{p}</span>"#));
        } else {
            nums.push(format!(
                r#"<a href="{}" class="inline-flex items-center justify-center w-8 h-8 rounded-lg text-sm text-blue-600 hover:bg-blue-50 transition no-underline">{p}</a>"#,
                escape_html(&mail_list_url(query, p, per_page))
            ));
        }
    }

    if end < last_page {
        if end < last_page - 1 {
            nums.push(r#"<span class="text-gray-300 px-1 text-sm">…</span>"#.to_string());
        }
        nums.push(format!(
            r#"<a href="{}" class="inline-flex items-center justify-center w-8 h-8 rounded-lg text-sm text-blue-600 hover:bg-blue-50 transition no-underline">{last_page}</a>"#,
            escape_html(&mail_list_url(query, last_page, per_page))
        ));
    }

    nums.join("\n")
}

fn mail_list_url(query: &MailListQuery, page: i64, per_page: i64) -> String {
    let mut params = Vec::new();
    if let Some(ref q) = query.q {
        if !q.trim().is_empty() {
            params.push(format!("q={}", url_encode(q)));
        }
    }
    if let Some(account_id) = query.account_id {
        params.push(format!("account_id={account_id}"));
    }
    if let Some(ref mailbox) = query.mailbox {
        if !mailbox.trim().is_empty() {
            params.push(format!("mailbox={}", url_encode(mailbox)));
        }
    }
    if let Some(ref source_key) = query.source_key {
        if !source_key.trim().is_empty() {
            params.push(format!("source_key={}", url_encode(source_key)));
        }
    }
    if let Some(seen) = query.seen {
        params.push(format!("seen={seen}"));
    }
    params.push(format!("page={}", page.max(1)));
    params.push(format!("per_page={}", per_page.clamp(1, 100)));
    format!("/mail?{}", params.join("&"))
}

fn url_encode(s: &str) -> String {
    let mut out = String::with_capacity(s.len());
    for b in s.bytes() {
        if b.is_ascii_alphanumeric() || matches!(b, b'-' | b'.' | b'_' | b'~') {
            out.push(b as char);
        } else {
            out.push_str(&format!("%{b:02X}"));
        }
    }
    out
}

// ═══════════════════════════════════════════════════════════
//  HTML 页面：邮件详情（移动端友好）
// ═══════════════════════════════════════════════════════════

async fn show_mail_message(
    Extension(state): Extension<MailRouteState>,
    Path(id): Path<i64>,
) -> Result<Html<String>, HtmlError> {
    let message = MailRepository::find(&state.db, id)
        .await
        .map_err(html_internal_error("读取邮件失败"))?
        .ok_or_else(|| html_not_found("邮件不存在", "没有找到对应的邮件记录"))?;

    let (prev_id, next_id) = MailRepository::find_adjacent_ids(&state.db, id)
        .await
        .map_err(html_internal_error("查询相邻邮件失败"))?;

    Ok(Html(render_mail_detail(&message, prev_id, next_id)))
}

fn render_mail_detail(msg: &MailMessage, prev_id: Option<i64>, next_id: Option<i64>) -> String {
    let subject = if msg.subject.trim().is_empty() {
        "无主题"
    } else {
        &msg.subject
    };
    let received = msg
        .received_at
        .as_ref()
        .map(|t| format_mail_time(t))
        .unwrap_or_else(|| "-".to_string());
    let account = msg
        .mail_account_id
        .map(|id| format!("账户 #{id}"))
        .unwrap_or_else(|| "环境配置".to_string());
    let mid_short = msg
        .message_id
        .as_deref()
        .map(|m| truncate(m, 72))
        .unwrap_or_else(|| "-".to_string());
    let preview_url = msg
        .preview_url
        .as_deref()
        .map(render_preview_url)
        .unwrap_or_else(|| "-".to_string());

    let is_html = content_is_html(&msg.content);
    let content_html = if is_html {
        let (body, styles) = extract_body_and_styles(&msg.content);
        let wrapped = render_sandboxed_html_email(&body, &styles);
        format!(
            r#"<div class="bg-white rounded-xl border border-gray-200 overflow-hidden">
  <iframe sandbox srcdoc="{}" class="w-full min-h-[420px] border-0 block bg-white" loading="lazy" title="邮件内容"></iframe>
</div>"#,
            escape_srcdoc(&wrapped)
        )
    } else {
        format!(
            r#"<article class="bg-white rounded-xl border border-gray-200 p-4 md:p-6 text-sm md:text-base leading-relaxed whitespace-normal break-words">{}</article>"#,
            render_text(&msg.content)
        )
    };

    let headers_html = msg.raw_headers.as_deref().filter(|h| !h.trim().is_empty()).map(|h| {
        format!(r#"<details class="bg-white rounded-xl border border-gray-200 overflow-hidden mb-4">
  <summary class="px-4 md:px-5 py-3 cursor-pointer text-sm font-semibold text-blue-600 hover:bg-gray-50 transition select-none">📋 原始头信息</summary>
  <pre class="m-0 px-4 md:px-5 py-4 text-xs leading-relaxed font-mono text-gray-700 whitespace-pre-wrap break-all border-t border-gray-100 max-h-80 overflow-y-auto">{}</pre>
</details>"#, escape_html(h))
    }).unwrap_or_default();

    // 导航按钮
    let prev_btn = match prev_id {
        Some(pid) => format!(r#"<a href="/mail/messages/{pid}" class="inline-flex items-center gap-1 px-3 md:px-4 py-2 rounded-lg text-sm font-medium border border-gray-200 bg-white text-blue-600 hover:border-blue-400 hover:bg-blue-50 transition no-underline">← 上一封</a>"#),
        None => r#"<span class="inline-flex items-center gap-1 px-3 md:px-4 py-2 rounded-lg text-sm border border-gray-200 bg-white text-gray-300 cursor-default">← 上一封</span>"#.to_string(),
    };
    let next_btn = match next_id {
        Some(nid) => format!(r#"<a href="/mail/messages/{nid}" class="inline-flex items-center gap-1 px-3 md:px-4 py-2 rounded-lg text-sm font-medium border border-gray-200 bg-white text-blue-600 hover:border-blue-400 hover:bg-blue-50 transition no-underline">下一封 →</a>"#),
        None => r#"<span class="inline-flex items-center gap-1 px-3 md:px-4 py-2 rounded-lg text-sm border border-gray-200 bg-white text-gray-300 cursor-default">下一封 →</span>"#.to_string(),
    };

    let body = format!(
        r#"<div class="flex items-center justify-between flex-wrap gap-2 mb-5">
  <a href="/mail" class="inline-flex items-center gap-1 text-sm text-blue-600 hover:text-blue-800 transition">← 邮件列表</a>
  <div class="flex gap-2">{prev_btn}{next_btn}</div>
</div>

<div class="bg-white rounded-xl border border-gray-200 p-4 md:p-6 mb-4 shadow-sm">
  <h1 class="text-lg md:text-xl font-bold leading-snug break-words mb-3">{subject}</h1>
  <div class="flex flex-wrap gap-x-4 gap-y-1.5 text-sm text-gray-500">
    <span class="inline-flex items-center gap-1"><span class="font-semibold text-gray-700">发件人</span>{from}</span>
    <span class="inline-flex items-center gap-1"><span class="font-semibold text-gray-700">时间</span>{received}</span>
    <span class="inline-flex items-center gap-1"><span class="font-semibold text-gray-700">来源</span>{source}</span>
  </div>
</div>

<details class="bg-white rounded-xl border border-gray-200 overflow-hidden mb-4">
  <summary class="px-4 md:px-5 py-3 cursor-pointer text-sm font-semibold text-blue-600 hover:bg-gray-50 transition select-none">📎 详细信息</summary>
  <dl class="grid grid-cols-1 md:grid-cols-[auto,1fr] gap-x-5 gap-y-2.5 p-4 md:p-5 pt-2 md:pt-3 border-t border-gray-100 text-sm">
    <dt class="text-gray-400 md:text-right">邮箱目录</dt><dd class="text-gray-700 break-all">{mailbox}</dd>
    <dt class="text-gray-400 md:text-right">状态</dt><dd class="text-gray-700">{seen_status}</dd>
    <dt class="text-gray-400 md:text-right">账户</dt><dd class="text-gray-700">{account}</dd>
    <dt class="text-gray-400 md:text-right">UID</dt>
    <dd class="text-gray-700 break-all"><code class="text-xs bg-gray-100 px-1.5 py-0.5 rounded">{uid}</code></dd>
    <dt class="text-gray-400 md:text-right">Message-ID</dt>
    <dd class="text-gray-700 break-all"><code class="text-xs bg-gray-100 px-1.5 py-0.5 rounded">{mid}</code></dd>
    <dt class="text-gray-400 md:text-right">缓存 ID</dt><dd class="text-gray-700">{id}</dd>
    <dt class="text-gray-400 md:text-right">原始大小</dt><dd class="text-gray-700">{size}</dd>
    <dt class="text-gray-400 md:text-right">入库时间</dt><dd class="text-gray-700">{created}</dd>
    <dt class="text-gray-400 md:text-right">提醒预览</dt><dd class="text-gray-700">{preview}</dd>
  </dl>
</details>

{content_html}
{headers_html}

<script>
  document.addEventListener('keydown', function(e) {{
    if (e.target.tagName === 'INPUT' || e.target.tagName === 'TEXTAREA') return;
    if (e.key === 'ArrowLeft') {{ var b = document.querySelector('a[href*="/mail/messages/"]:not([href="/mail"])'); if (b && b.textContent.includes('上一封')) b.click(); }}
    if (e.key === 'ArrowRight') {{ var links = document.querySelectorAll('a[href*="/mail/messages/"]:not([href="/mail"])'); links.forEach(function(l) {{ if (l.textContent.includes('下一封')) l.click(); }}); }}
  }});
</script>"#,
        subject = escape_html(subject),
        from = escape_html(&msg.from_label),
        received = escape_html(&received),
        source = escape_html(&msg.source_key),
        mailbox = escape_html(&msg.mailbox),
        seen_status = if msg.seen { "已读" } else { "未读" },
        account = escape_html(&account),
        uid = escape_html(&msg.uid),
        mid = escape_html(&mid_short),
        id = msg.id,
        size = format_bytes(msg.raw_size),
        created = format_mail_time(&msg.created_at),
        preview = preview_url,
        content_html = content_html,
        headers_html = headers_html,
        prev_btn = prev_btn,
        next_btn = next_btn,
    );

    html_shell(&format!("{subject} — 邮件"), &body)
}

// ── 辅助函数 ─────────────────────────────────────────────

fn content_is_html(content: &str) -> bool {
    let trimmed = content.trim();
    if trimmed.is_empty() {
        return false;
    }
    let lower = trimmed
        .chars()
        .take(1024)
        .collect::<String>()
        .to_lowercase();
    lower.contains("<html")
        || lower.contains("<!doctype")
        || lower.contains("<body")
        || lower.contains("<div")
        || lower.contains("<table")
        || lower.contains("<meta")
        || lower.contains("<head")
        || lower.contains("<a href")
        || lower.contains("<p ")
        || lower.contains("<br")
        || lower.contains("<img")
        || lower.contains("<span")
}

fn extract_body_and_styles(html: &str) -> (String, String) {
    let lower = html.to_lowercase();

    // 提取 head 中的 style 标签内容
    let styles = if let Some(head_start) = lower.find("<head") {
        let head_content_start = lower[head_start..]
            .find('>')
            .map(|i| head_start + i + 1)
            .unwrap_or(head_start);
        if let Some(head_end) = lower[head_content_start..].find("</head>") {
            let head_html = &html[head_content_start..head_content_start + head_end];
            extract_style_tags(head_html)
        } else {
            String::new()
        }
    } else {
        String::new()
    };

    // 提取 body 内容，没有 body 则返回全部
    let body = if let Some(body_start) = lower.find("<body") {
        let tag_end = lower[body_start..]
            .find('>')
            .map(|i| body_start + i + 1)
            .unwrap_or(body_start);
        if let Some(body_end) = lower[tag_end..].find("</body>") {
            html[tag_end..tag_end + body_end].to_string()
        } else {
            html[tag_end..].to_string()
        }
    } else {
        html.to_string()
    };

    (body, styles)
}

fn extract_style_tags(head_html: &str) -> String {
    let lower = head_html.to_lowercase();
    let mut styles = String::new();
    let mut pos = 0;
    while let Some(style_start) = lower[pos..].find("<style") {
        let abs_start = pos + style_start;
        let content_start = lower[abs_start..]
            .find('>')
            .map(|i| abs_start + i + 1)
            .unwrap_or(abs_start);
        if let Some(style_end) = lower[content_start..].find("</style>") {
            let style_content = &head_html[content_start..content_start + style_end];
            if !styles.is_empty() {
                styles.push('\n');
            }
            styles.push_str(style_content);
            pos = content_start + style_end + "</style>".len();
        } else {
            break;
        }
    }
    styles
}

fn render_preview_url(url: &str) -> String {
    let url = url.trim();
    if !is_safe_http_url(url) {
        return escape_html(url);
    }

    let escaped = escape_html(url);
    format!(
        r#"<a href="{escaped}" target="_blank" rel="noopener noreferrer" class="text-blue-600 hover:underline break-all">{escaped}</a>"#
    )
}

fn is_safe_http_url(url: &str) -> bool {
    let normalized = url.trim_start().to_ascii_lowercase();
    normalized.starts_with("http://") || normalized.starts_with("https://")
}

fn render_sandboxed_html_email(body: &str, styles: &str) -> String {
    let styles = if styles.is_empty() {
        String::new()
    } else {
        format!("<style>{styles}</style>")
    };

    format!(
        r#"<!doctype html><html><head><meta charset="utf-8"><meta http-equiv="Content-Security-Policy" content="default-src 'none'; img-src data: cid: https: http:; style-src 'unsafe-inline'; base-uri 'none'; form-action 'none'">{styles}</head><body>{body}</body></html>"#
    )
}

/// 转义 HTML 使其安全放入 srcdoc 属性。
fn escape_srcdoc(html: &str) -> String {
    escape_html(html)
}

fn render_text(content: &str) -> String {
    // 清理 \r 并规范化换行
    let cleaned = content.replace("\r\n", "\n").replace('\r', "\n");
    let paragraphs: Vec<&str> = cleaned.split("\n\n").collect();

    paragraphs
        .iter()
        .map(|p| {
            let p = p.trim();
            if p.is_empty() {
                return String::new();
            }
            let lines: Vec<String> = p
                .lines()
                .map(|line| {
                    let line = line.trim();
                    if line.is_empty() {
                        "<br>".to_string()
                    } else {
                        escape_html(line)
                    }
                })
                .collect();
            format!("<p class=\"mb-2 last:mb-0\">{}</p>", lines.join("<br>\n"))
        })
        .filter(|s| !s.is_empty())
        .collect::<Vec<_>>()
        .join("\n")
}

fn truncate(s: &str, max: usize) -> String {
    let count = s.chars().count();
    if count <= max {
        s.to_string()
    } else {
        let truncated: String = s.chars().take(max - 1).collect();
        format!("{truncated}…")
    }
}

fn format_mail_time(t: &chrono::DateTime<chrono::Utc>) -> String {
    t.format("%Y-%m-%d %H:%M UTC").to_string()
}

fn relative_time(t: &chrono::DateTime<chrono::Utc>) -> String {
    let delta = chrono::Utc::now().signed_duration_since(*t);
    if delta.num_seconds() < 60 {
        "刚刚".to_string()
    } else if delta.num_minutes() < 60 {
        format!("{} 分钟前", delta.num_minutes())
    } else if delta.num_hours() < 24 {
        format!("{} 小时前", delta.num_hours())
    } else if delta.num_days() < 30 {
        format!("{} 天前", delta.num_days())
    } else {
        String::new()
    }
}

fn format_bytes(bytes: i64) -> String {
    if bytes < 1024 {
        format!("{bytes} B")
    } else if bytes < 1024 * 1024 {
        format!("{:.1} KB", bytes as f64 / 1024.0)
    } else {
        format!("{:.2} MB", bytes as f64 / (1024.0 * 1024.0))
    }
}

// ── 错误处理 ─────────────────────────────────────────────

fn html_not_found(title: &str, msg: &str) -> HtmlError {
    let body = format!(
        r#"<h1 class="text-2xl font-bold">{title}</h1>
<p class="mt-2 text-gray-500">{msg}</p>
<p class="mt-4"><a href="/mail" class="text-blue-600 hover:text-blue-800">返回邮件列表</a></p>"#
    );
    (StatusCode::NOT_FOUND, Html(html_shell(title, &body)))
}

fn html_internal_error(msg: &str) -> impl Fn(anyhow::Error) -> HtmlError + use<> {
    let msg = msg.to_string();
    move |error: anyhow::Error| -> HtmlError {
        eprintln!("{msg}: {error}");
        let body = format!(
            r#"<h1 class="text-2xl font-bold">页面暂时不可用</h1>
<p class="mt-2 text-gray-500">{msg}，请稍后重试。</p>
<p class="mt-4"><a href="/mail" class="text-blue-600 hover:text-blue-800">返回邮件列表</a></p>"#
        );
        (
            StatusCode::INTERNAL_SERVER_ERROR,
            Html(html_shell("页面不可用", &body)),
        )
    }
}

fn api_not_found(message: impl Into<String>) -> ApiError {
    (
        StatusCode::NOT_FOUND,
        Json(json!({
            "success": false,
            "message": message.into(),
        })),
    )
}

fn api_internal_error(error: anyhow::Error) -> ApiError {
    eprintln!("mail 接口失败: {error}");
    (
        StatusCode::INTERNAL_SERVER_ERROR,
        Json(json!({
            "success": false,
            "message": "mail 接口失败",
        })),
    )
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn content_is_html_handles_long_unicode_prefix() {
        let content = format!("{}<html><body>ok</body></html>", "邮件".repeat(700));
        let _ = content_is_html(&content);
    }

    #[test]
    fn truncate_handles_unicode_boundaries() {
        let value = "邮件".repeat(80);
        let truncated = truncate(&value, 72);

        assert_eq!(truncated.chars().count(), 72);
        assert!(truncated.ends_with('…'));
    }

    #[test]
    fn render_preview_url_escapes_href_attribute() {
        let html = render_preview_url("https://example.test/?q=\" onmouseover=\"x");

        assert!(html.contains("https://example.test/?q=&quot; onmouseover=&quot;x"));
        assert!(!html.contains("q=\" onmouseover=\"x"));
    }

    #[test]
    fn render_preview_url_rejects_non_http_protocols() {
        let html = render_preview_url("javascript:alert(1)");

        assert_eq!(html, "javascript:alert(1)");
    }

    #[test]
    fn render_sandboxed_html_email_blocks_scripts_and_forms() {
        let html = render_sandboxed_html_email("<img src=\"https://example.test/pixel.png\">", "");

        assert!(html.contains("default-src 'none'"));
        assert!(html.contains("img-src data: cid: https: http:"));
        assert!(html.contains("form-action 'none'"));
    }
}