import json
import secrets
from datetime import datetime

from db import get_db, get_setting, set_setting, get_site_name, index_url, clean_url
from templates import esc, snippet, wrap_page, DEFAULT_TEMPLATE
from rns_client import fetch_remote_sites

_csrf_token = secrets.token_hex(32)


def _csrf_field():
    return f'<input type="hidden" name="_csrf" value="{_csrf_token}">'


def _check_csrf(body):
    token = body.get("_csrf", [""])[0]
    return secrets.compare_digest(token, _csrf_token)


def _sanitize_fts_query(query):
    """Escape user input for safe use in FTS5 MATCH."""
    escaped = query.replace('"', '""')
    return f'"{escaped}"'


def _respond(body_html, status=200, use_default=False):
    return {
        "status": status,
        "content_type": "text/html; charset=utf-8",
        "body": wrap_page(body_html, use_default=use_default),
        "headers": {},
    }


def _redirect(location):
    return {
        "status": 302,
        "content_type": "text/html; charset=utf-8",
        "body": "",
        "headers": {"Location": location},
    }


def _json_response(data, status=200, headers=None):
    return {
        "status": status,
        "content_type": "application/json",
        "body": json.dumps(data, indent=2),
        "headers": headers or {},
    }


def _text_response(text, status=200, headers=None):
    return {
        "status": status,
        "content_type": "text/plain",
        "body": text,
        "headers": headers or {},
    }


def _error(status):
    return _respond(f"<h1>{status}</h1>", status)


# --- Tag helpers ---


def _get_page_tags(page_id, db=None):
    close = False
    if db is None:
        db = get_db()
        close = True
    rows = db.execute(
        "SELECT t.name FROM tags t JOIN page_tags pt ON t.id = pt.tag_id "
        "WHERE pt.page_id = ? ORDER BY t.name", (page_id,)
    ).fetchall()
    if close:
        db.close()
    return [r["name"] for r in rows]


def _set_page_tags(page_id, tag_string, db=None):
    close = False
    if db is None:
        db = get_db()
        close = True
    db.execute("DELETE FROM page_tags WHERE page_id = ?", (page_id,))
    for name in (t.strip().lower() for t in tag_string.split(",") if t.strip()):
        db.execute("INSERT OR IGNORE INTO tags (name) VALUES (?)", (name,))
        tag_id = db.execute("SELECT id FROM tags WHERE name = ?", (name,)).fetchone()["id"]
        db.execute("INSERT OR IGNORE INTO page_tags (page_id, tag_id) VALUES (?, ?)", (page_id, tag_id))
    if close:
        db.commit()
        db.close()


# --- Route handlers ---


def handle_search(query):
    q = query.get("q", [""])[0].strip()
    db = get_db()
    count = db.execute("SELECT count(*) FROM pages").fetchone()[0]
    name = get_site_name()

    result_html = ""
    trusted_html = ""
    if q:
        try:
            rows = db.execute(
                "SELECT p.id, p.url, p.title, p.body, p.note "
                "FROM pages_fts f JOIN pages p ON f.rowid = p.id "
                "WHERE pages_fts MATCH ? ORDER BY rank LIMIT 50",
                (_sanitize_fts_query(q),),
            ).fetchall()
        except Exception:
            rows = []
        if rows:
            for r in rows:
                note_html = ""
                if r["note"]:
                    note_html = f'<div class="note"><em>{esc(r["note"])}</em></div>'
                tags = _get_page_tags(r["id"], db)
                tags_html = ""
                if tags:
                    tag_links = " ".join(f'<a href="/tags/{esc(t)}" class="tag">[{esc(t)}]</a>' for t in tags)
                    tags_html = f'<div class="tags">{tag_links}</div>'
                result_html += (
                    f'<div class="result">'
                    f'<a href="{esc(r["url"])}">{esc(r["title"])}</a><br>'
                    f'<small>{esc(r["url"])}</small><br>'
                    f'{esc(snippet(r["body"], q))}'
                    f'{note_html}{tags_html}'
                    f'</div>'
                )
        else:
            result_html = "<p>No results in your index.</p>"

        # search all linked pages from trusted sites
        words = q.lower().split()
        all_links = db.execute(
            "SELECT l.url, l.label, p.title AS source_title "
            "FROM links l JOIN pages p ON l.page_id = p.id",
        ).fetchall()
        indexed_urls = set(r["url"] for r in rows) if rows else set()
        seen = set()
        trusted = []
        for l in all_links:
            if l["url"] in indexed_urls or l["url"] in seen:
                continue
            if any(w in l["label"].lower() for w in words):
                seen.add(l["url"])
                trusted.append(l)
            if len(trusted) >= 20:
                break

        if trusted:
            items = ""
            for l in trusted:
                items += (
                    f'<li><a href="{esc(l["url"])}">{esc(l["label"])}</a> '
                    f'<small>— from {esc(l["source_title"])}</small></li>'
                )
            trusted_html = (
                f'<details class="trusted">'
                f'<summary>from your trusted sites ({len(trusted)})</summary>'
                f'<ul>{items}</ul>'
                f'</details>'
            )

        # search synced pages from subscriptions
        try:
            remote_rows = db.execute(
                "SELECT rp.url, rp.title, rp.note, s.name AS source_name "
                "FROM remote_pages_fts rpf "
                "JOIN remote_pages rp ON rpf.rowid = rp.id "
                "JOIN subscriptions s ON rp.subscription_id = s.id "
                "WHERE remote_pages_fts MATCH ? ORDER BY rank LIMIT 50",
                (_sanitize_fts_query(q),),
            ).fetchall()
        except Exception:
            remote_rows = []

    remote_html = ""
    if q and remote_rows:
        # group by source
        by_source = {}
        for r in remote_rows:
            source = r["source_name"] or "unknown"
            by_source.setdefault(source, []).append(r)
        for source, items in by_source.items():
            source_items = ""
            for r in items:
                note_html = f' — <em>{esc(r["note"])}</em>' if r["note"] else ""
                source_items += (
                    f'<li><a href="{esc(r["url"])}">{esc(r["title"])}</a>'
                    f'{note_html} <small>({esc(r["url"])})</small></li>'
                )
            remote_html += (
                f'<details class="remote" open>'
                f'<summary>from {esc(source)} ({len(items)})</summary>'
                f'<ul>{source_items}</ul>'
                f'</details>'
            )

    db.close()
    sub_count = ""
    if q and remote_rows:
        sub_count = f" + {len(remote_rows)} from subscriptions"
    return _respond(
        f'<form method="get" action="/">'
        f'<input name="q" value="{esc(q)}" placeholder="search your index" size="40">'
        f' <button type="submit">search</button>'
        f'</form>'
        f'<p class="meta">{count} pages indexed'
        f' · <a href="/add">+ add url</a></p>'
        f'{result_html}{trusted_html}{remote_html}'
    )


def handle_add_form(msg=""):
    return _respond(
        f"<h1>add url</h1>"
        f'<form method="post" action="/add">'
        f'{_csrf_field()}'
        f'<input name="url" placeholder="https://example.com" size="50"><br><br>'
        f'<input name="note" placeholder="why are you saving this? (optional)" size="50"><br><br>'
        f'<input name="tags" placeholder="tags (comma-separated, e.g. solarpunk, mesh)" size="50"><br><br>'
        f'<button type="submit">index</button>'
        f"</form>"
        f"<p>{msg}</p>"
        f'<a href="/">back</a>'
    )


def handle_add_submit(body):
    url = clean_url(body.get("url", [""])[0].strip())
    note = body.get("note", [""])[0].strip()
    tags = body.get("tags", [""])[0].strip()
    if not url:
        return handle_add_form("URL is required.")
    if not url.startswith(("http://", "https://")):
        return handle_add_form("URL must start with http:// or https://")
    try:
        title = index_url(url, note)
        if tags:
            db = get_db()
            row = db.execute("SELECT id FROM pages WHERE url = ?", (url,)).fetchone()
            if row:
                _set_page_tags(row["id"], tags, db)
                db.commit()
            db.close()
        return handle_add_form(f'Indexed: <a href="{esc(url)}">{esc(title)}</a>')
    except Exception as e:
        return handle_add_form(f"Error: {esc(str(e))}")


def handle_pages():
    db = get_db()
    rows = db.execute("SELECT id, url, title, note FROM pages ORDER BY id DESC").fetchall()
    items = ""
    for r in rows:
        note_html = f' — <em>{esc(r["note"])}</em>' if r["note"] else ""
        tags = _get_page_tags(r["id"], db)
        tags_html = ""
        if tags:
            tag_links = " ".join(f'<a href="/tags/{esc(t)}">[{esc(t)}]</a>' for t in tags)
            tags_html = f' {tag_links}'
        items += (
            f'<li>{esc(r["title"])}{note_html}{tags_html} '
            f'<small>(<a href="{esc(r["url"])}">{esc(r["url"])}</a>)</small> '
            f'<a href="/edit/{r["id"]}">edit</a> '
            f'<a href="/delete/{r["id"]}">remove</a></li>'
        )
    db.close()
    return _respond(
        f"<h1>indexed pages ({len(rows)})</h1>"
        f"<ul>{items}</ul>"
        f'<p><a href="/export">export</a> | <a href="/import">import</a></p>'
        f'<a href="/">back</a>'
    )


def handle_edit_form(page_id, msg=""):
    db = get_db()
    row = db.execute("SELECT id, url, title, note FROM pages WHERE id = ?", (page_id,)).fetchone()
    if not row:
        db.close()
        return _error(404)
    tags = ", ".join(_get_page_tags(page_id, db))
    db.close()
    return _respond(
        f"<h1>edit page</h1>"
        f"<p><b>{esc(row['title'])}</b><br>"
        f"<small>{esc(row['url'])}</small></p>"
        f'<form method="post" action="/edit/{row["id"]}">'
        f'{_csrf_field()}'
        f'<input name="note" value="{esc(row["note"])}" placeholder="why did you save this?" size="50"><br><br>'
        f'<input name="tags" value="{esc(tags)}" placeholder="tags (comma-separated)" size="50"><br><br>'
        f'<button type="submit">save</button>'
        f"</form>"
        f"<p>{msg}</p>"
        f'<a href="/pages">back</a>'
    )


def handle_edit_submit(page_id, body):
    note = body.get("note", [""])[0].strip()
    tags = body.get("tags", [""])[0].strip()
    db = get_db()
    db.execute("UPDATE pages SET note = ? WHERE id = ?", (note, page_id))
    _set_page_tags(page_id, tags, db)
    db.commit()
    db.close()
    return _redirect("/pages")


def handle_delete_confirm(page_id):
    db = get_db()
    row = db.execute("SELECT id, url, title FROM pages WHERE id = ?", (page_id,)).fetchone()
    db.close()
    if not row:
        return _error(404)
    return _respond(
        f"<h1>confirm delete</h1>"
        f"<p>Remove <b>{esc(row['title'])}</b><br>"
        f"<small>{esc(row['url'])}</small></p>"
        f'<form method="post" action="/delete/{row["id"]}">'
        f'{_csrf_field()}'
        f'<button type="submit">yes, delete</button>'
        f"</form>"
        f' <a href="/pages">cancel</a>'
    )


def handle_delete(page_id):
    db = get_db()
    db.execute("DELETE FROM links WHERE page_id = ?", (page_id,))
    db.execute("DELETE FROM pages WHERE id = ?", (page_id,))
    db.commit()
    db.close()
    return _redirect("/pages")


def handle_bookmark(query):
    url = clean_url(query.get("url", [""])[0].strip())
    if not url or not url.startswith(("http://", "https://")):
        return _text_response("error: invalid url", headers={"Access-Control-Allow-Origin": "*"})
    try:
        title = index_url(url)
        msg = f"ok: {title}"
    except Exception as e:
        msg = f"error: {e}"
    return _text_response(msg, headers={"Access-Control-Allow-Origin": "*"})


def handle_export():
    db = get_db()
    rows = db.execute("SELECT url, title, note FROM pages ORDER BY id").fetchall()
    db.close()
    data = [{"url": r["url"], "title": r["title"], "note": r["note"]} for r in rows]
    return _json_response(data, headers={"Content-Disposition": "attachment; filename=tinyweb-export.json"})


def handle_import_form(msg=""):
    return _respond(
        f"<h1>import</h1>"
        f"<p>Paste the contents of a tinyweb export file (JSON).</p>"
        f'<form method="post" action="/import">'
        f'{_csrf_field()}'
        f'<textarea name="data" rows="12" cols="60" placeholder=\'[{{"url": "...", "note": "..."}}]\'></textarea><br><br>'
        f'<button type="submit">import</button>'
        f"</form>"
        f"<p>{msg}</p>"
        f'<a href="/pages">back</a>'
    )


def handle_import_submit(body):
    raw = body.get("data", [""])[0].strip()
    if not raw:
        return handle_import_form("Paste JSON data.")
    try:
        data = json.loads(raw)
    except json.JSONDecodeError:
        return handle_import_form("Invalid JSON.")
    if not isinstance(data, list):
        return handle_import_form("Expected a JSON array.")

    imported = 0
    errors = 0
    for entry in data:
        url = entry.get("url", "").strip()
        note = entry.get("note", "").strip()
        if not url:
            continue
        try:
            index_url(url, note)
            imported += 1
        except Exception:
            errors += 1

    return handle_import_form(f"Imported {imported} page(s). {errors} error(s).")


def handle_style_form(msg="", query=None):
    if query and "reset" in query:
        set_setting("custom_template", "")
        msg = "Template reset to default."
    template = get_setting("custom_template") or DEFAULT_TEMPLATE
    name = get_site_name()
    sharing = get_setting("sharing_enabled", "0")
    checked = " checked" if sharing == "1" else ""
    return _respond(
        f"<h1>customize</h1>"
        f"<h2>name your search engine</h2>"
        f'<form method="post" action="/style">'
        f'{_csrf_field()}'
        f'<input name="site_name" value="{esc(name)}" placeholder="tinyweb" size="30"><br><br>'
        f"<h2>sharing</h2>"
        f'<label><input type="checkbox" name="sharing_enabled" value="1"{checked}>'
        f" share your site list publicly at /api/sites</label><br><br>"
        f"<h2>custom html</h2>"
        f"<p>Edit the full page template. Use <code>{esc('{{content}}')}</code> "
        f"where page content should appear.</p>"
        f'<textarea name="template" rows="20" cols="60">{esc(template)}</textarea><br><br>'
        f'<button type="submit">save</button>'
        f"</form>"
        f"<h2>bookmarklet</h2>"
        f"<p>Drag this link to your bookmarks bar. Click it on any page to index it instantly.</p>"
        f'<p><a href="javascript:void(fetch(\'http://localhost:8080/bookmark?url=\'+encodeURIComponent(location.href)).then(r=>r.text()).then(t=>alert(t)).catch(()=>alert(\'tinyweb not running\')))">+ save to {esc(name)}</a></p>'
        f"<p>{msg}</p>"
        f'<a href="/">back</a>',
        use_default=True,
    )


def handle_style_submit(body):
    template = body.get("template", [""])[0]
    name = body.get("site_name", ["tinyweb"])[0].strip()
    sharing = "1" if body.get("sharing_enabled") else "0"
    set_setting("custom_template", template if template.strip() != DEFAULT_TEMPLATE.strip() else "")
    set_setting("site_name", name or "tinyweb")
    set_setting("sharing_enabled", sharing)
    return handle_style_form("Saved.")


def handle_about():
    name = get_site_name()
    dest_hash = get_setting("dest_hash")
    sharing = get_setting("sharing_enabled", "0") == "1"
    db = get_db()
    page_count = db.execute("SELECT count(*) FROM pages").fetchone()[0]
    tag_count = db.execute("SELECT count(DISTINCT tag_id) FROM page_tags").fetchone()[0]
    sub_count = db.execute("SELECT count(*) FROM subscriptions").fetchone()[0]
    db.close()

    sharing_html = (
        '<p>This instance shares its index publicly. Subscribe to join the network.</p>'
        if sharing else
        '<p>This instance is private.</p>'
    )

    hash_html = ""
    if dest_hash:
        hash_html = (
            f'<h2>subscribe</h2>'
            f'<p>To subscribe to this instance, add this destination hash in your TinyWeb:</p>'
            f'<pre>{esc(dest_hash)}</pre>'
        )

    return _respond(
        f'<h1>{esc(name)}</h1>'
        f'<p>A personal search engine, built for the slow web.</p>'
        f'<p>TinyWeb is about taking back the internet. No algorithms, no ads, no tracking. '
        f'Just human-curated pages shared freely across a mesh network.</p>'
        f'<ul>'
        f'<li><b>{page_count}</b> page(s) indexed</li>'
        f'<li><b>{tag_count}</b> tag(s)</li>'
        f'<li><b>{sub_count}</b> subscription(s)</li>'
        f'</ul>'
        f'{sharing_html}'
        f'{hash_html}'
        f'<h2>what is the slow web?</h2>'
        f'<p>The slow web is a movement for intentionality over speed, '
        f'human curation over algorithmic feeds, privacy over surveillance, '
        f'and community over corporations. Every page in this index was saved by a person '
        f'because they found it valuable — not because an algorithm told them to click.</p>'
        f'<h2>how it works</h2>'
        f'<ul>'
        f'<li>Save pages you find valuable with the bookmarklet or /add</li>'
        f'<li>Search your personal index — queries never leave your machine</li>'
        f'<li>Subscribe to friends over Reticulum — encrypted, decentralized, works without the internet</li>'
        f'<li>Tag and organize your collection into curated lists</li>'
        f'</ul>'
        f'<p><a href="/">search</a> | <a href="/pages">browse</a> | <a href="/tags">tags</a></p>'
    )


def handle_tags():
    db = get_db()
    rows = db.execute(
        "SELECT t.name, COUNT(pt.page_id) AS cnt FROM tags t "
        "JOIN page_tags pt ON t.id = pt.tag_id "
        "GROUP BY t.id ORDER BY t.name"
    ).fetchall()
    db.close()
    items = ""
    for r in rows:
        items += f'<li><a href="/tags/{esc(r["name"])}">{esc(r["name"])}</a> ({r["cnt"]})</li>'
    return _respond(
        f"<h1>tags</h1>"
        f"<ul>{items}</ul>" if items else "<p>No tags yet. Add tags when saving or editing pages.</p>"
        f'<a href="/">back</a>'
    )


def handle_tag_browse(tag_name):
    db = get_db()
    rows = db.execute(
        "SELECT p.id, p.url, p.title, p.note FROM pages p "
        "JOIN page_tags pt ON p.id = pt.page_id "
        "JOIN tags t ON t.id = pt.tag_id "
        "WHERE t.name = ? ORDER BY p.id DESC",
        (tag_name,),
    ).fetchall()
    items = ""
    for r in rows:
        note_html = f' — <em>{esc(r["note"])}</em>' if r["note"] else ""
        tags = _get_page_tags(r["id"], db)
        tag_links = " ".join(f'<a href="/tags/{esc(t)}">[{esc(t)}]</a>' for t in tags)
        items += (
            f'<li>{esc(r["title"])}{note_html} {tag_links} '
            f'<small>(<a href="{esc(r["url"])}">{esc(r["url"])}</a>)</small></li>'
        )
    db.close()
    return _respond(
        f'<h1>tag: {esc(tag_name)}</h1>'
        f'<p>{len(rows)} page(s)</p>'
        f'<ul>{items}</ul>'
        f'<a href="/tags">all tags</a> | <a href="/">back</a>'
    )


def handle_api_sites():
    if get_setting("sharing_enabled", "0") != "1":
        return _json_response(
            {"error": "sharing disabled"},
            status=403,
            headers={"Access-Control-Allow-Origin": "*"},
        )
    db = get_db()
    rows = db.execute("SELECT id, url, title, note FROM pages ORDER BY id DESC").fetchall()
    sites = []
    for r in rows:
        tags = _get_page_tags(r["id"], db)
        sites.append({"url": r["url"], "title": r["title"], "note": r["note"], "tags": tags})
    db.close()
    data = {"name": get_site_name(), "sites": sites}
    return _json_response(data, headers={"Access-Control-Allow-Origin": "*"})


def handle_subscriptions(msg=""):
    db = get_db()
    subs = db.execute("SELECT * FROM subscriptions ORDER BY id DESC").fetchall()
    db.close()
    items = ""
    for s in subs:
        auto_label = "on" if s["auto_sync"] else "off"
        last = s["last_sync"] or "never"
        items += (
            f'<tr>'
            f'<td><b>{esc(s["name"] or "unknown")}</b><br><small>{esc(s["dest_hash"])}</small></td>'
            f'<td>{esc(last)}</td>'
            f'<td>'
            f'<form method="post" action="/subscriptions/autosync/{s["id"]}" style="display:inline">'
            f'{_csrf_field()}<button>auto-sync: {auto_label}</button></form>'
            f'</td>'
            f'<td>'
            f'<a href="/subscriptions/browse/{s["id"]}">browse</a> '
            f'<form method="post" action="/subscriptions/sync/{s["id"]}" style="display:inline">'
            f'{_csrf_field()}<button>sync now</button></form> '
            f'<form method="post" action="/subscriptions/delete/{s["id"]}" style="display:inline">'
            f'{_csrf_field()}<button>remove</button></form>'
            f'</td>'
            f'</tr>'
        )
    table = ""
    if subs:
        table = (
            f'<table><tr><th>instance</th><th>last sync</th><th>auto-sync</th><th>actions</th></tr>'
            f'{items}</table>'
            f'<form method="post" action="/subscriptions/syncall">'
            f'{_csrf_field()}<button>sync all</button></form>'
        )
    return _respond(
        f"<h1>subscriptions</h1>"
        f'<form method="post" action="/subscriptions/add">'
        f'{_csrf_field()}'
        f'<input name="dest_hash" placeholder="destination hash" size="40"> '
        f'<button>subscribe</button>'
        f'</form>'
        f'<p>{msg}</p>'
        f'<hr>{table}'
        f'<br><a href="/">back</a>'
    )


def handle_subscription_add(body):
    dest_hash = body.get("dest_hash", [""])[0].strip().replace("<", "").replace(">", "")
    if not dest_hash or len(dest_hash) != 32:
        return handle_subscriptions("Enter a valid 32-character destination hash.")
    try:
        int(dest_hash, 16)
    except ValueError:
        return handle_subscriptions("Invalid destination hash (must be hex).")
    try:
        data = fetch_remote_sites(dest_hash)
        name = data.get("name", "")
    except PermissionError:
        return handle_subscriptions("That instance has sharing disabled.")
    except Exception as e:
        return handle_subscriptions(f"Could not reach that instance: {esc(str(e))}")
    db = get_db()
    try:
        db.execute(
            "INSERT INTO subscriptions (dest_hash, name) VALUES (?, ?) "
            "ON CONFLICT(dest_hash) DO UPDATE SET name=excluded.name",
            (dest_hash, name),
        )
        db.commit()
    finally:
        db.close()
    return handle_subscriptions(f"Subscribed to {esc(name or dest_hash)}.")


def handle_subscription_browse(sub_id):
    db = get_db()
    sub = db.execute("SELECT * FROM subscriptions WHERE id = ?", (sub_id,)).fetchone()
    if not sub:
        db.close()
        return _error(404)
    local_urls = set(r["url"] for r in db.execute("SELECT url FROM pages").fetchall())

    # Use locally synced data if available, otherwise fetch live
    remote_rows = db.execute(
        "SELECT url, title, note, tags FROM remote_pages WHERE subscription_id = ?",
        (sub_id,),
    ).fetchall()
    db.close()

    if remote_rows:
        sites = []
        for r in remote_rows:
            tags = [t for t in r["tags"].split(",") if t] if r["tags"] else []
            sites.append({"url": r["url"], "title": r["title"], "note": r["note"], "tags": tags})
    else:
        try:
            data = fetch_remote_sites(sub["dest_hash"])
            sites = data.get("sites", [])
        except PermissionError:
            return handle_subscriptions("That instance has sharing disabled.")
        except Exception as e:
            return handle_subscriptions(f"Could not fetch sites: {esc(str(e))}")

    new_items = ""
    existing_items = ""
    new_count = 0
    for s in sites:
        if s["url"] in local_urls:
            existing_items += (
                f'<li style="opacity:0.5">{esc(s["title"])} '
                f'<small>({esc(s["url"])})</small> — already indexed</li>'
            )
        else:
            new_count += 1
            note_html = f' — <em>{esc(s["note"])}</em>' if s.get("note") else ""
            tags_html = ""
            if s.get("tags"):
                tags_html = " " + " ".join(f'[{esc(t)}]' for t in s["tags"])
            new_items += (
                f'<li><label><input type="checkbox" name="urls" value="{esc(s["url"])}">'
                f' {esc(s["title"])}{note_html}{tags_html}'
                f' <small>({esc(s["url"])})</small></label></li>'
            )

    buttons = ""
    if new_count:
        buttons = '<button>import selected</button> <button name="import_all" value="1">import all new</button>'
    return _respond(
        f'<h1>browsing: {esc(sub["name"] or sub["dest_hash"])}</h1>'
        f'<p>{len(sites)} site(s) available, {new_count} new</p>'
        f'<form method="post" action="/subscriptions/pick">'
        f'{_csrf_field()}'
        f'<input type="hidden" name="sub_id" value="{sub_id}">'
        f'<ul>{new_items}</ul>'
        f'{buttons}'
        f'</form>'
        f'<h3>already indexed</h3><ul>{existing_items}</ul>'
        f'<a href="/subscriptions">back</a>'
    )


def handle_subscription_pick(body):
    sub_id = body.get("sub_id", [""])[0]
    import_all = body.get("import_all", [""])[0]

    # Build a url->tags map from remote_pages for this subscription
    db = get_db()
    remote_rows = db.execute(
        "SELECT url, tags FROM remote_pages WHERE subscription_id = ?", (sub_id,)
    ).fetchall()
    remote_tags = {r["url"]: r["tags"] for r in remote_rows}

    if import_all:
        local_urls = set(r["url"] for r in db.execute("SELECT url FROM pages").fetchall())
        urls = [r["url"] for r in remote_rows if r["url"] not in local_urls]
    else:
        urls = body.get("urls", [])
    db.close()

    if not urls:
        return handle_subscriptions("No sites selected.")

    imported = 0
    errors = 0
    for url in urls:
        try:
            index_url(url)
            # Import tags from the remote page
            tags_str = remote_tags.get(url, "")
            if tags_str:
                db = get_db()
                row = db.execute("SELECT id FROM pages WHERE url = ?", (url,)).fetchone()
                if row:
                    _set_page_tags(row["id"], tags_str, db)
                    db.commit()
                db.close()
            imported += 1
        except Exception:
            errors += 1
    return handle_subscriptions(f"Imported {imported} page(s). {errors} error(s).")


def handle_subscription_sync(sub_id):
    db = get_db()
    sub = db.execute("SELECT * FROM subscriptions WHERE id = ?", (sub_id,)).fetchone()
    if not sub:
        db.close()
        return handle_subscriptions("Subscription not found.")
    try:
        data = fetch_remote_sites(sub["dest_hash"])
        sites = data.get("sites", [])
        remote_name = data.get("name", sub["name"])
    except PermissionError:
        db.close()
        return handle_subscriptions("That instance has sharing disabled.")
    except Exception as e:
        db.close()
        return handle_subscriptions(f"Could not sync: {esc(str(e))}")

    # Clear old remote pages for this subscription and re-insert
    db.execute("DELETE FROM remote_pages WHERE subscription_id = ?", (sub_id,))
    synced = 0
    for s in sites:
        try:
            tags_str = ",".join(s.get("tags", []))
            db.execute(
                "INSERT INTO remote_pages (subscription_id, url, title, note, tags) VALUES (?, ?, ?, ?, ?)",
                (sub_id, s["url"], s["title"], s.get("note", ""), tags_str),
            )
            synced += 1
        except Exception:
            pass
    now = datetime.now().strftime("%Y-%m-%d %H:%M")
    db.execute("UPDATE subscriptions SET last_sync = ?, name = ? WHERE id = ?", (now, remote_name, sub_id))
    db.commit()
    db.close()
    return handle_subscriptions(f"Synced {synced} site(s) from {esc(remote_name)}.")


def handle_subscription_autosync(sub_id):
    db = get_db()
    db.execute("UPDATE subscriptions SET auto_sync = 1 - auto_sync WHERE id = ?", (sub_id,))
    db.commit()
    db.close()
    return _redirect("/subscriptions")


def handle_subscription_delete(sub_id):
    db = get_db()
    db.execute("DELETE FROM remote_pages WHERE subscription_id = ?", (sub_id,))
    db.execute("DELETE FROM subscriptions WHERE id = ?", (sub_id,))
    db.commit()
    db.close()
    return _redirect("/subscriptions")


def handle_subscription_syncall():
    db = get_db()
    subs = db.execute("SELECT * FROM subscriptions WHERE auto_sync = 1").fetchall()
    db.close()
    if not subs:
        return handle_subscriptions("No subscriptions have auto-sync enabled.")
    total = 0
    for sub in subs:
        try:
            data = fetch_remote_sites(sub["dest_hash"])
            sites = data.get("sites", [])
            remote_name = data.get("name", sub["name"])
            db = get_db()
            db.execute("DELETE FROM remote_pages WHERE subscription_id = ?", (sub["id"],))
            for s in sites:
                try:
                    tags_str = ",".join(s.get("tags", []))
                    db.execute(
                        "INSERT INTO remote_pages (subscription_id, url, title, note, tags) VALUES (?, ?, ?, ?, ?)",
                        (sub["id"], s["url"], s["title"], s.get("note", ""), tags_str),
                    )
                except Exception:
                    pass
            now = datetime.now().strftime("%Y-%m-%d %H:%M")
            db.execute("UPDATE subscriptions SET last_sync = ?, name = ? WHERE id = ?", (now, remote_name, sub["id"]))
            db.commit()
            db.close()
            total += 1
        except Exception:
            pass
    return handle_subscriptions(f"Synced {total} subscription(s).")


# --- Dispatcher ---


def dispatch_request(data):
    method = data.get("method", "GET")
    path = data.get("path", "/")
    query = data.get("query", {})
    body = data.get("body", {})
    gateway_host = data.get("gateway_host", "")

    def extract_id(prefix):
        try:
            return int(path[len(prefix):])
        except (ValueError, IndexError):
            return None

    if method == "GET":
        if path == "/":
            return handle_search(query)
        elif path == "/add":
            return handle_add_form()
        elif path == "/pages":
            return handle_pages()
        elif path.startswith("/edit/"):
            pid = extract_id("/edit/")
            return handle_edit_form(pid) if pid is not None else _error(400)
        elif path.startswith("/delete/"):
            pid = extract_id("/delete/")
            return handle_delete_confirm(pid) if pid is not None else _error(400)
        elif path == "/bookmark":
            return handle_bookmark(query)
        elif path == "/style":
            return handle_style_form(query=query)
        elif path == "/about":
            return handle_about()
        elif path == "/export":
            return handle_export()
        elif path == "/import":
            return handle_import_form()
        elif path == "/tags":
            return handle_tags()
        elif path.startswith("/tags/"):
            tag_name = path[len("/tags/"):]
            return handle_tag_browse(tag_name) if tag_name else _error(400)
        elif path == "/api/sites":
            return handle_api_sites()
        elif path == "/subscriptions":
            return handle_subscriptions()
        elif path.startswith("/subscriptions/browse/"):
            sid = extract_id("/subscriptions/browse/")
            return handle_subscription_browse(sid) if sid is not None else _error(400)
    elif method == "POST":
        if not _check_csrf(body):
            return _respond("<h1>403 Forbidden</h1><p>Invalid or missing CSRF token.</p>", status=403)
        if path == "/add":
            return handle_add_submit(body)
        elif path.startswith("/edit/"):
            pid = extract_id("/edit/")
            return handle_edit_submit(pid, body) if pid is not None else _error(400)
        elif path.startswith("/delete/"):
            pid = extract_id("/delete/")
            return handle_delete(pid) if pid is not None else _error(400)
        elif path == "/style":
            return handle_style_submit(body)
        elif path == "/import":
            return handle_import_submit(body)
        elif path == "/subscriptions/add":
            return handle_subscription_add(body)
        elif path == "/subscriptions/pick":
            return handle_subscription_pick(body)
        elif path.startswith("/subscriptions/sync/"):
            sid = extract_id("/subscriptions/sync/")
            return handle_subscription_sync(sid) if sid is not None else _error(400)
        elif path.startswith("/subscriptions/autosync/"):
            sid = extract_id("/subscriptions/autosync/")
            return handle_subscription_autosync(sid) if sid is not None else _error(400)
        elif path.startswith("/subscriptions/delete/"):
            sid = extract_id("/subscriptions/delete/")
            return handle_subscription_delete(sid) if sid is not None else _error(400)
        elif path == "/subscriptions/syncall":
            return handle_subscription_syncall()

    return _error(404)