//! The local SQLite store: every operation the repository seam needs, as plain
//! functions over a `&Connection`. The Tauri commands (commands.rs) lock the shared
//! connection and call these; keeping the SQL here (off the command layer) makes it
//! unit-testable against an in-memory database.
//!
//! Timestamps are emitted exactly like JS `Date.toISOString()`
//! ("YYYY-MM-DDTHH:MM:SS.sssZ") so string ordering and date-range comparisons line
//! up with the values the frontend sends.

use chrono::{DateTime, Duration, SecondsFormat, Utc};
use rusqlite::{params, params_from_iter, Connection, OptionalExtension};
use serde_json::{json, Value};
use uuid::Uuid;

use crate::local::derive;
use crate::local::models::*;
use crate::local::recur;

fn now() -> String {
    Utc::now().to_rfc3339_opts(SecondsFormat::Millis, true)
}

fn new_id() -> String {
    Uuid::new_v4().to_string()
}

/// The note's NAME: the first line of its body that says anything.
///
/// Mirrors `derive_display_title` in the server's notes/helpers.py — one rule written
/// twice, and they have to agree or a synced note is called different things on either
/// side of the wire.
///
/// It no longer needs the items, because the items ARE lines of the body now (M304).
/// What it needs instead is to strip the task marker off: a list-only note is still
/// named by its first item, and calling that note "- [ ] milk" would be showing
/// someone the storage rather than the note. An empty item is skipped rather than
/// naming the note "", which is what a half-typed list would otherwise do.
fn display_title(body: &str) -> String {
    for line in body.lines() {
        let text = derive::strip_marker(line.trim()).trim();
        if !text.is_empty() {
            return text.to_string();
        }
    }
    String::new()
}

fn escape_like(s: &str) -> String {
    s.replace('\\', "\\\\")
        .replace('%', "\\%")
        .replace('_', "\\_")
}

// ---- note assembly ----------------------------------------------------------

fn load_labels(conn: &Connection, note_id: &str) -> rusqlite::Result<Vec<NoteLabel>> {
    let mut stmt = conn.prepare(
        "SELECT l.id, l.name, l.color, nl.via_tag
         FROM note_labels nl JOIN labels l ON l.id = nl.label_id
         WHERE nl.note_id = ?1 ORDER BY l.name COLLATE NOCASE",
    )?;
    let rows = stmt.query_map([note_id], |r| {
        Ok(NoteLabel {
            id: r.get(0)?,
            name: r.get(1)?,
            color: r.get(2)?,
            via_tag: r.get(3)?,
        })
    })?;
    rows.collect()
}

/// The note's checklist, read out of its body. No query, because there is no table.
///
/// A `- [ ] milk` line IS the item (M304). The id is the item's ORDINAL rather than a
/// uuid — which is all it ever amounted to anyway, since `push.rs` sent text and
/// checked and never an id, and both sides replaced the whole list on every sync. It
/// is also exactly what the rewriters in `derive` take, so a UI holding an id can act
/// on it directly.
fn items_of(body: &str) -> Vec<ChecklistItem> {
    derive::extract_items(body)
        .into_iter()
        .enumerate()
        .map(|(i, item)| ChecklistItem {
            id: i.to_string(),
            text: item.text,
            checked: item.checked,
            position: i as i64,
        })
        .collect()
}

fn load_attachments(conn: &Connection, note_id: &str) -> rusqlite::Result<Vec<Attachment>> {
    let mut stmt = conn.prepare(
        "SELECT id, url, filename, mime, size, sha256 FROM attachments WHERE note_id = ?1 ORDER BY position ASC",
    )?;
    let rows = stmt.query_map([note_id], |r| {
        let server_url: String = r.get(1)?;
        let mime: String = r.get(3)?;
        let sha256: Option<String> = r.get(5)?;
        Ok(Attachment {
            id: r.get(0)?,
            // Point at the LOCAL bytes, not the server's route. The stored url is the
            // server's relative path, which resolves against the app origin in the
            // webview and 404s — and even absolute it would need a bearer token the
            // webview never sends. Rewriting here rather than at each render site
            // means NoteCard and NoteEditor stay untouched and can't drift.
            //
            // Without a hash there's nothing to address the blob by (an older server
            // that predates the sha256 column), so the original url is left alone:
            // still broken, but no more broken than it already was.
            url: match sha256.as_deref() {
                Some(hash) if !hash.is_empty() => crate::sync::blobs::url_for(hash, &mime),
                _ => server_url,
            },
            filename: r.get(2)?,
            mime,
            size: r.get(4)?,
            sha256,
        })
    })?;
    rows.collect()
}

fn load_previews(conn: &Connection, note_id: &str) -> rusqlite::Result<Vec<LinkPreview>> {
    let mut stmt = conn.prepare(
        "SELECT id, url, title, description, image_url, site_name FROM link_previews WHERE note_id = ?1 ORDER BY position ASC",
    )?;
    let rows = stmt.query_map([note_id], |r| {
        Ok(LinkPreview {
            id: r.get(0)?,
            url: r.get(1)?,
            title: r.get(2)?,
            description: r.get(3)?,
            image_url: r.get(4)?,
            site_name: r.get(5)?,
        })
    })?;
    rows.collect()
}

fn load_note(conn: &Connection, id: &str) -> rusqlite::Result<Note> {
    let mut note = conn.query_row(
        "SELECT id, body, position, pinned, archived, trashed, remind_at, recurrence, created_at, updated_at, trashed_at
         FROM notes WHERE id = ?1",
        [id],
        |r| {
            let body: String = r.get(1)?;
            Ok(Note {
                id: r.get(0)?,
                display_title: String::new(), // filled below — it may need a query
                body,
                position: r.get(2)?,
                pinned: r.get(3)?,
                archived: r.get(4)?,
                trashed: r.get(5)?,
                deleted_at: r.get(10)?,
                remind_at: r.get(6)?,
                recurrence: r.get(7)?,
                labels: Vec::new(),
                items: Vec::new(),
                attachments: Vec::new(),
                previews: Vec::new(),
                created_at: r.get(9)?,
                updated_at: r.get(10)?,
            })
        },
    )?;
    note.labels = load_labels(conn, id)?;
    note.items = items_of(&note.body);
    note.attachments = load_attachments(conn, id)?;
    note.previews = load_previews(conn, id)?;
    note.display_title = display_title(&note.body);
    Ok(note)
}

fn touch(conn: &Connection, id: &str) -> rusqlite::Result<()> {
    conn.execute(
        "UPDATE notes SET updated_at = ?1, dirty = 1 WHERE id = ?2",
        params![now(), id],
    )?;
    Ok(())
}

// ---- #tag -> label derivation ----------------------------------------------

fn find_or_create_label(conn: &Connection, name: &str) -> rusqlite::Result<String> {
    let existing: Option<String> = conn
        .query_row(
            "SELECT id FROM labels WHERE lower(name) = lower(?1)",
            [name],
            |r| r.get(0),
        )
        .optional()?;
    if let Some(id) = existing {
        return Ok(id);
    }
    let id = new_id();
    let ts = now();
    conn.execute(
        "INSERT INTO labels (id, name, color, created_at, updated_at, dirty) VALUES (?1, ?2, 'default', ?3, ?3, 1)",
        params![id, name, ts],
    )?;
    Ok(id)
}

/// Attach the note's tag labels, LIFT its standalone tags out of the body, and write
/// the shortened body back.
///
/// NAMED FOR THE MUTATION. It used to be `sync_tags` and only touched label rows; it
/// now rewrites `notes.body`, and every caller writes the body just before calling —
/// so this overwrites what they wrote, on purpose.
///
/// `display_title` needs no attention here, unlike on the server: the core derives it
/// on READ (see `display_title` above, called from `load_note`) rather than storing
/// it, so there is no persisted copy to go stale.
///
/// The two kinds of tag are handled differently, and that difference IS what `via_tag`
/// means from here on — backed by text still in the body:
///
///   standalone  lifted out, attached as an ORDINARY label. Nothing derives it any
///               more, and the way to remove it becomes the chip's ×.
///   inline      left in place, attached via_tag = 1, still detached when its text
///               goes. Unchanged from before.
///
/// Mirrors `_lift_and_reconcile_tags` in the server's `notes/tags.py`.
fn lift_and_sync_tags(conn: &Connection, note_id: &str, body: &str) -> rusqlite::Result<()> {
    let (standalone, inline, lifted) = derive::lift_standalone_tags(body);

    let mut standalone_ids: Vec<String> = Vec::with_capacity(standalone.len());
    for name in &standalone {
        standalone_ids.push(find_or_create_label(conn, name)?);
    }
    let mut inline_ids: Vec<String> = Vec::with_capacity(inline.len());
    for name in &inline {
        inline_ids.push(find_or_create_label(conn, name)?);
    }

    let current: Vec<(String, bool)> = {
        let mut stmt =
            conn.prepare("SELECT label_id, via_tag FROM note_labels WHERE note_id = ?1")?;
        let rows = stmt.query_map([note_id], |r| {
            Ok((r.get::<_, String>(0)?, r.get::<_, bool>(1)?))
        })?;
        rows.collect::<rusqlite::Result<Vec<(String, bool)>>>()?
    };

    for (lid, via_tag) in &current {
        if !*via_tag {
            continue; // manual already: a #tag of the same name changes nothing
        }
        if standalone_ids.contains(lid) {
            // It GRADUATED. The text backing it is about to go, so the row has to
            // become the record instead — and BEFORE the delete below, or the same row
            // is dropped for no longer being in the body. That is the bug a naive lift
            // has, and it silently loses the tag.
            conn.execute(
                "UPDATE note_labels SET via_tag = 0 WHERE note_id = ?1 AND label_id = ?2",
                params![note_id, lid],
            )?;
        } else if !inline_ids.contains(lid) {
            conn.execute(
                "DELETE FROM note_labels WHERE note_id = ?1 AND label_id = ?2 AND via_tag = 1",
                params![note_id, lid],
            )?;
        }
    }

    // OR IGNORE leaves a label already attached in ANY form alone, which is what keeps
    // a manually-added label of the same name manual.
    for lid in &standalone_ids {
        conn.execute(
            "INSERT OR IGNORE INTO note_labels (note_id, label_id, via_tag) VALUES (?1, ?2, 0)",
            params![note_id, lid],
        )?;
    }
    for lid in &inline_ids {
        conn.execute(
            "INSERT OR IGNORE INTO note_labels (note_id, label_id, via_tag) VALUES (?1, ?2, 1)",
            params![note_id, lid],
        )?;
    }

    if lifted != body {
        conn.execute(
            "UPDATE notes SET body = ?1 WHERE id = ?2",
            params![lifted, note_id],
        )?;
    }
    Ok(())
}

// ---- notes: read ------------------------------------------------------------

pub fn list_notes(conn: &Connection, q: &ListQuery) -> rusqlite::Result<Vec<Note>> {
    let mut sql = String::from("SELECT id FROM notes WHERE ");
    sql.push_str(match q.view.as_str() {
        "trash" => "trashed = 1",
        "archived" => "trashed = 0 AND archived = 1",
        _ => "trashed = 0 AND archived = 0",
    });

    let mut binds: Vec<String> = Vec::new();

    // Label filters (sidebar label + facet labels) are ANDed: a note must carry all.
    let mut label_ids: Vec<String> = Vec::new();
    if let Some(l) = q.label_id.as_deref().filter(|s| !s.is_empty()) {
        label_ids.push(l.to_string());
    }
    if let Some(f) = &q.facets {
        if let Some(ls) = &f.label {
            for l in ls.iter().filter(|s| !s.is_empty()) {
                label_ids.push(l.clone());
            }
        }
    }
    for lid in &label_ids {
        sql.push_str(" AND EXISTS (SELECT 1 FROM note_labels nl WHERE nl.note_id = notes.id AND nl.label_id = ?)");
        binds.push(lid.clone());
    }

    if let Some(f) = &q.facets {
        if let Some(text) = f.q.as_deref().filter(|s| !s.is_empty()) {
            sql.push_str(" AND body LIKE ? ESCAPE '\\'");
            let pat = format!("%{}%", escape_like(text));
            binds.push(pat.clone());
            binds.push(pat);
        }
        if f.has_reminder == Some(true) {
            sql.push_str(" AND remind_at IS NOT NULL");
        }
        if f.has_attachment == Some(true) {
            sql.push_str(" AND EXISTS (SELECT 1 FROM attachments a WHERE a.note_id = notes.id)");
        }
        if let Some(a) = f.created_after.as_deref().filter(|s| !s.is_empty()) {
            sql.push_str(" AND created_at >= ?");
            binds.push(a.to_string());
        }
        if let Some(b) = f.created_before.as_deref().filter(|s| !s.is_empty()) {
            sql.push_str(" AND created_at < ?");
            binds.push(b.to_string());
        }
    }

    sql.push_str(if q.sort.as_deref() == Some("created") {
        " ORDER BY created_at DESC"
    } else {
        " ORDER BY pinned DESC, position DESC, updated_at DESC"
    });

    let ids: Vec<String> = {
        let mut stmt = conn.prepare(&sql)?;
        let rows = stmt.query_map(params_from_iter(binds.iter()), |r| r.get::<_, String>(0))?;
        rows.collect::<rusqlite::Result<Vec<String>>>()?
    };
    ids.iter().map(|id| load_note(conn, id)).collect()
}

pub fn get_note(conn: &Connection, id: &str) -> rusqlite::Result<Note> {
    load_note(conn, id)
}

pub fn reminders(conn: &Connection) -> rusqlite::Result<Vec<Note>> {
    let ids: Vec<String> = {
        let mut stmt =
            conn.prepare("SELECT id FROM notes WHERE trashed = 0 AND remind_at IS NOT NULL ORDER BY remind_at ASC")?;
        let rows = stmt.query_map([], |r| r.get::<_, String>(0))?;
        rows.collect::<rusqlite::Result<Vec<String>>>()?
    };
    ids.iter().map(|id| load_note(conn, id)).collect()
}

pub fn titles(conn: &Connection) -> rusqlite::Result<Vec<TitleEntry>> {
    // Names come from `load_note` rather than from a bare row, because a note whose
    // body is empty is named by its first checklist item — which a row here doesn't
    // have. The command palette reads this; correctness beats one query per note at
    // personal scale.
    let ids: Vec<String> = {
        let mut stmt = conn.prepare("SELECT id FROM notes WHERE trashed = 0")?;
        let rows = stmt.query_map([], |r| r.get(0))?;
        rows.collect::<rusqlite::Result<Vec<String>>>()?
    };
    ids.iter()
        .map(|id| {
            let note = load_note(conn, id)?;
            Ok(TitleEntry {
                id: note.id,
                title: note.display_title,
            })
        })
        .collect()
}

pub fn search(conn: &Connection, q: &str) -> rusqlite::Result<Vec<Note>> {
    let pat = format!("%{}%", escape_like(q));
    let ids: Vec<String> = {
        let mut stmt = conn.prepare(
            "SELECT id FROM notes WHERE trashed = 0 AND body LIKE ?1 ESCAPE '\\' ORDER BY updated_at DESC",
        )?;
        let rows = stmt.query_map([&pat], |r| r.get::<_, String>(0))?;
        rows.collect::<rusqlite::Result<Vec<String>>>()?
    };
    ids.iter().map(|id| load_note(conn, id)).collect()
}

// ---- notes: write -----------------------------------------------------------

pub fn create_note(conn: &Connection, input: &NoteCreateInput) -> rusqlite::Result<Note> {
    let id = new_id();
    let ts = now();
    let position: i64 = conn.query_row(
        "SELECT COALESCE(MAX(position), 0) + 1 FROM notes",
        [],
        |r| r.get(0),
    )?;
    // Items fold into the body rather than into rows of their own. Callers still hand
    // them over separately — the importer has a list, not a blob — but where they end
    // up is one place.
    let mut body = input.body.clone();
    if let Some(items) = &input.items {
        for text in items {
            body = derive::append_item(&body, text, false);
        }
    }
    conn.execute(
        "INSERT INTO notes (id, body, position, created_at, updated_at, dirty)
         VALUES (?1, ?2, ?3, ?4, ?4, 1)",
        params![id, body, position, ts],
    )?;
    // The FOLDED body, not the input one: an item can carry a #tag too.
    lift_and_sync_tags(conn, &id, &body)?;
    load_note(conn, &id)
}

/// How long one editing session is assumed to last.
///
/// Inside this window a note's body may be written any number of times and only the
/// FIRST write snapshots. That is what makes an idle-debounced autosave affordable:
/// a write costs a write, not a write plus a revision.
const REVISION_WINDOW_MINUTES: i64 = 10;

/// Whether a body change earns a snapshot of the pre-edit body.
///
/// Two conditions. The body must actually differ — re-saving identical text is not a
/// version of anything. And the note must not already carry a revision from this
/// editing session.
///
/// The session rule is what keeps version history worth reading. Because
/// [`snapshot_revision`] stores the body as it was BEFORE the edit, the first write
/// of a session captures the note as you found it, and every write after it inside
/// the window adds nothing. One revision per sitting falls out of the window on its
/// own — no "commit" the client has to declare, and no protocol surface to carry it,
/// which matters because sync-apply takes this same path.
fn should_snapshot(conn: &Connection, id: &str, new_body: &str) -> rusqlite::Result<bool> {
    let current: String =
        conn.query_row("SELECT body FROM notes WHERE id = ?1", [id], |r| r.get(0))?;
    if current == new_body {
        return Ok(false);
    }
    // String comparison, not date maths: timestamps are RFC3339 UTC with a fixed
    // millisecond field (see the module header), so lexical order IS chronological.
    let cutoff = (Utc::now() - Duration::minutes(REVISION_WINDOW_MINUTES))
        .to_rfc3339_opts(SecondsFormat::Millis, true);
    let recent: i64 = conn.query_row(
        "SELECT COUNT(*) FROM note_revisions WHERE note_id = ?1 AND created_at >= ?2",
        params![id, cutoff],
        |r| r.get(0),
    )?;
    Ok(recent == 0)
}

fn snapshot_revision(conn: &Connection, id: &str) -> rusqlite::Result<()> {
    let body: String =
        conn.query_row("SELECT body FROM notes WHERE id = ?1", [id], |r| r.get(0))?;
    conn.execute(
        "INSERT INTO note_revisions (id, note_id, body, created_at) VALUES (?1, ?2, ?3, ?4)",
        params![new_id(), id, body, now()],
    )?;
    Ok(())
}

/// PATCH semantics: apply exactly the fields present in `changes`.
pub fn update_note(conn: &Connection, id: &str, changes: &Value) -> rusqlite::Result<Note> {
    let obj = changes
        .as_object()
        .ok_or_else(|| rusqlite::Error::InvalidParameterName("changes must be an object".into()))?;

    // Snapshot the pre-edit body before changing it (version history) — but only
    // once per editing session, and only if it actually changed. See should_snapshot.
    if let Some(body) = obj.get("body").and_then(|v| v.as_str()) {
        if should_snapshot(conn, id, body)? {
            snapshot_revision(conn, id)?;
        }
    }

    for (k, v) in obj {
        match k.as_str() {
            "body" => {
                let body = v.as_str().unwrap_or("");
                conn.execute(
                    "UPDATE notes SET body = ?1 WHERE id = ?2",
                    params![body, id],
                )?;
                lift_and_sync_tags(conn, id, body)?;
            }
            "pinned" => {
                if let Some(b) = v.as_bool() {
                    conn.execute("UPDATE notes SET pinned = ?1 WHERE id = ?2", params![b, id])?;
                }
            }
            "archived" => {
                if let Some(b) = v.as_bool() {
                    conn.execute(
                        "UPDATE notes SET archived = ?1 WHERE id = ?2",
                        params![b, id],
                    )?;
                }
            }
            "remind_at" => {
                let val = v.as_str().map(|s| s.to_string());
                conn.execute(
                    "UPDATE notes SET remind_at = ?1 WHERE id = ?2",
                    params![val, id],
                )?;
            }
            "recurrence" => {
                let val = v.as_str().map(|s| s.to_string());
                conn.execute(
                    "UPDATE notes SET recurrence = ?1 WHERE id = ?2",
                    params![val, id],
                )?;
            }
            _ => {}
        }
    }

    touch(conn, id)?;
    load_note(conn, id)
}

/// Mark a reminder handled.
///
/// A recurring reminder advances to its next occurrence; a one-off clears both
/// `remind_at` AND `recurrence`. Clearing the rule as well matters: without it a
/// note whose recurrence is a value we do not recognise would keep that value
/// forever, invisible in every UI (they only render known rules) and waiting to
/// mean something the day the vocabulary grows.
///
/// Same behaviour as the server's `POST /<id>/reminder/complete`, deliberately —
/// the same note can be completed from a browser or from a client, and a
/// disagreement here would move a reminder depending on which one you used.
pub fn complete_reminder(conn: &Connection, id: &str) -> rusqlite::Result<Note> {
    let note = load_note(conn, id)?;
    let next = note
        .remind_at
        .as_deref()
        .and_then(|at| DateTime::parse_from_rfc3339(at).ok())
        .and_then(|at| {
            let rule = recur::normalize(note.recurrence.as_deref())?;
            recur::next_occurrence(at.with_timezone(&Utc), rule, Utc::now())
        });

    match next {
        Some(at) => conn.execute(
            "UPDATE notes SET remind_at = ?1 WHERE id = ?2",
            params![at.to_rfc3339_opts(SecondsFormat::Millis, true), id],
        )?,
        None => conn.execute(
            "UPDATE notes SET remind_at = NULL, recurrence = NULL WHERE id = ?1",
            [id],
        )?,
    };
    touch(conn, id)?;
    load_note(conn, id)
}

pub fn snooze_reminder(conn: &Connection, id: &str, minutes: i64) -> rusqlite::Result<Note> {
    let t = (Utc::now() + Duration::minutes(minutes)).to_rfc3339_opts(SecondsFormat::Millis, true);
    conn.execute(
        "UPDATE notes SET remind_at = ?1 WHERE id = ?2",
        params![t, id],
    )?;
    touch(conn, id)?;
    load_note(conn, id)
}

pub fn set_labels(conn: &Connection, id: &str, label_ids: &[String]) -> rusqlite::Result<Note> {
    // Manual labels are replaced wholesale; #tag (via_tag) labels are managed by text.
    conn.execute(
        "DELETE FROM note_labels WHERE note_id = ?1 AND via_tag = 0",
        [id],
    )?;
    for lid in label_ids {
        conn.execute(
            "INSERT OR IGNORE INTO note_labels (note_id, label_id, via_tag) VALUES (?1, ?2, 0)",
            params![id, lid],
        )?;
    }
    touch(conn, id)?;
    load_note(conn, id)
}

// ---- checklist items: every one of these is a body edit ---------------------
//
// They keep their own names and signatures because the FFI, the Tauri commands and
// the REST shape all speak in items, and a checklist is still a thing a note HAS.
// What changed is where it is kept. Routing all three through `update_note` rather
// than writing the body directly is what gives them revision snapshotting, `#tag`
// re-derivation and the dirty/updated_at bookkeeping without any of it being
// written a second time here.

fn note_body(conn: &Connection, id: &str) -> rusqlite::Result<String> {
    conn.query_row("SELECT body FROM notes WHERE id = ?1", [id], |r| r.get(0))
}

/// An item's id is its ordinal (see [items_of]). Anything else is a stale id from a
/// UI that has not reloaded, and the right answer to those is to do nothing.
fn item_index(item_id: &str) -> Option<usize> {
    item_id.parse::<usize>().ok()
}

fn set_body(conn: &Connection, id: &str, body: String) -> rusqlite::Result<Note> {
    update_note(conn, id, &json!({ "body": body }))
}

pub fn add_item(conn: &Connection, id: &str, text: &str) -> rusqlite::Result<Note> {
    let body = note_body(conn, id)?;
    set_body(conn, id, derive::append_item(&body, text, false))
}

pub fn update_item(
    conn: &Connection,
    id: &str,
    item_id: &str,
    changes: &Value,
) -> rusqlite::Result<Note> {
    let index = match item_index(item_id) {
        Some(i) => i,
        None => return load_note(conn, id),
    };
    let mut body = note_body(conn, id)?;
    if let Some(text) = changes.get("text").and_then(Value::as_str) {
        body = derive::set_item_text(&body, index, text);
    }
    if let Some(checked) = changes.get("checked").and_then(Value::as_bool) {
        body = derive::set_item_checked(&body, index, checked);
    }
    set_body(conn, id, body)
}

pub fn delete_item(conn: &Connection, id: &str, item_id: &str) -> rusqlite::Result<Note> {
    let index = match item_index(item_id) {
        Some(i) => i,
        None => return load_note(conn, id),
    };
    let body = note_body(conn, id)?;
    set_body(conn, id, derive::remove_item(&body, index))
}

pub fn delete_attachment(conn: &Connection, id: &str, att_id: &str) -> rusqlite::Result<Note> {
    conn.execute(
        "DELETE FROM attachments WHERE id = ?1 AND note_id = ?2",
        params![att_id, id],
    )?;
    touch(conn, id)?;
    load_note(conn, id)
}

pub fn delete_preview(conn: &Connection, id: &str, preview_id: &str) -> rusqlite::Result<Note> {
    conn.execute(
        "DELETE FROM link_previews WHERE id = ?1 AND note_id = ?2",
        params![preview_id, id],
    )?;
    touch(conn, id)?;
    load_note(conn, id)
}

pub fn reorder(conn: &Connection, ordered_ids: &[String]) -> rusqlite::Result<()> {
    let total = ordered_ids.len() as i64;
    for (i, id) in ordered_ids.iter().enumerate() {
        conn.execute(
            "UPDATE notes SET position = ?1, dirty = 1 WHERE id = ?2",
            params![total - i as i64, id],
        )?;
    }
    Ok(())
}

pub fn trash(conn: &Connection, id: &str) -> rusqlite::Result<Note> {
    // COALESCE, so trashing an already-trashed note doesn't restart its retention
    // clock. The server keeps its `deleted_at` the same way — a note shouldn't earn
    // another 30 days because something touched it twice.
    conn.execute(
        "UPDATE notes SET trashed = 1, trashed_at = COALESCE(trashed_at, ?1) WHERE id = ?2",
        params![now(), id],
    )?;
    touch(conn, id)?;
    load_note(conn, id)
}

pub fn restore(conn: &Connection, id: &str) -> rusqlite::Result<Note> {
    conn.execute(
        "UPDATE notes SET trashed = 0, trashed_at = NULL WHERE id = ?1",
        [id],
    )?;
    touch(conn, id)?;
    load_note(conn, id)
}

pub fn delete_forever(conn: &Connection, id: &str) -> rusqlite::Result<()> {
    record_pending_delete(conn, "note", id)?;
    conn.execute("DELETE FROM notes WHERE id = ?1", [id])?;
    Ok(())
}

/// Remember that a row was permanently deleted, so the sync engine can tell the
/// server. Without this the deleted row leaves no trace at all, and the next pull
/// would resurrect it — a delete that quietly undoes itself.
///
/// Harmless when the app is unlinked: the row is simply never read, and a later push
/// gets a `noop` for an id the server never had.
pub fn record_pending_delete(conn: &Connection, entity: &str, id: &str) -> rusqlite::Result<()> {
    conn.execute(
        "INSERT OR REPLACE INTO pending_deletes (entity, id, deleted_at) VALUES (?1, ?2, ?3)",
        params![entity, id, now()],
    )?;
    Ok(())
}

// ---- device-local preferences (schema v5) -----------------------------------

/// A stored preference, or `None` if it was never set. Callers supply their own
/// default rather than one being invented here — the meaning of "unset" belongs
/// with the setting, not with the storage.
pub fn pref(conn: &Connection, key: &str) -> rusqlite::Result<Option<String>> {
    conn.query_row("SELECT value FROM prefs WHERE key = ?1", [key], |r| {
        r.get(0)
    })
    .optional()
}

pub fn set_pref(conn: &Connection, key: &str, value: &str) -> rusqlite::Result<()> {
    conn.execute(
        "INSERT INTO prefs (key, value) VALUES (?1, ?2)
         ON CONFLICT(key) DO UPDATE SET value = excluded.value",
        params![key, value],
    )?;
    Ok(())
}

pub fn revisions(conn: &Connection, id: &str) -> rusqlite::Result<Vec<NoteRevision>> {
    let mut stmt = conn
        .prepare("SELECT id, body, created_at FROM note_revisions WHERE note_id = ?1 ORDER BY created_at DESC")?;
    let rows = stmt.query_map([id], |r| {
        Ok(NoteRevision {
            id: r.get(0)?,
            body: r.get(1)?,
            created_at: r.get(2)?,
        })
    })?;
    rows.collect()
}

pub fn restore_revision(conn: &Connection, id: &str, rev_id: &str) -> rusqlite::Result<Note> {
    let body: String = conn.query_row(
        "SELECT body FROM note_revisions WHERE id = ?1 AND note_id = ?2",
        params![rev_id, id],
        |r| r.get(0),
    )?;
    snapshot_revision(conn, id)?;
    conn.execute(
        "UPDATE notes SET body = ?1 WHERE id = ?2",
        params![body, id],
    )?;
    lift_and_sync_tags(conn, id, &body)?;
    touch(conn, id)?;
    load_note(conn, id)
}

// ---- labels -----------------------------------------------------------------

fn load_label(conn: &Connection, id: &str) -> rusqlite::Result<Label> {
    conn.query_row(
        "SELECT l.id, l.name, l.color,
                (SELECT COUNT(*) FROM note_labels nl JOIN notes n ON n.id = nl.note_id
                 WHERE nl.label_id = l.id AND n.trashed = 0)
         FROM labels l WHERE l.id = ?1",
        [id],
        |r| {
            Ok(Label {
                id: r.get(0)?,
                name: r.get(1)?,
                color: r.get(2)?,
                count: Some(r.get(3)?),
            })
        },
    )
}

pub fn list_labels(conn: &Connection) -> rusqlite::Result<Vec<Label>> {
    let mut stmt = conn.prepare(
        "SELECT l.id, l.name, l.color,
                (SELECT COUNT(*) FROM note_labels nl JOIN notes n ON n.id = nl.note_id
                 WHERE nl.label_id = l.id AND n.trashed = 0)
         FROM labels l ORDER BY l.name COLLATE NOCASE",
    )?;
    let rows = stmt.query_map([], |r| {
        Ok(Label {
            id: r.get(0)?,
            name: r.get(1)?,
            color: r.get(2)?,
            count: Some(r.get(3)?),
        })
    })?;
    rows.collect()
}

pub fn create_label(conn: &Connection, name: &str) -> rusqlite::Result<Label> {
    let id = find_or_create_label(conn, name)?;
    load_label(conn, &id)
}

pub fn rename_label(conn: &Connection, id: &str, name: &str) -> rusqlite::Result<Label> {
    conn.execute(
        "UPDATE labels SET name = ?1, updated_at = ?2, dirty = 1 WHERE id = ?3",
        params![name, now(), id],
    )?;
    load_label(conn, id)
}

pub fn set_label_color(conn: &Connection, id: &str, color: &str) -> rusqlite::Result<Label> {
    conn.execute(
        "UPDATE labels SET color = ?1, updated_at = ?2, dirty = 1 WHERE id = ?3",
        params![color, now(), id],
    )?;
    load_label(conn, id)
}

pub fn remove_label(conn: &Connection, id: &str) -> rusqlite::Result<()> {
    record_pending_delete(conn, "label", id)?;
    conn.execute("DELETE FROM labels WHERE id = ?1", [id])?;
    Ok(())
}

pub fn merge_labels(
    conn: &Connection,
    source_id: &str,
    target_id: &str,
) -> rusqlite::Result<Label> {
    conn.execute(
        "INSERT OR IGNORE INTO note_labels (note_id, label_id, via_tag)
         SELECT note_id, ?2, 0 FROM note_labels WHERE label_id = ?1",
        params![source_id, target_id],
    )?;
    // The notes that carried the source now have a different label set, and that set
    // only reaches the server via the note itself (push sends label_ids per note).
    // Without this the merge would look done locally and never sync. Marked BEFORE
    // the delete, which cascades the membership rows away.
    conn.execute(
        "UPDATE notes SET dirty = 1
          WHERE id IN (SELECT note_id FROM note_labels WHERE label_id = ?1)",
        [source_id],
    )?;
    record_pending_delete(conn, "label", source_id)?;
    conn.execute("DELETE FROM labels WHERE id = ?1", [source_id])?;
    load_label(conn, target_id)
}

// ---- saved filters ----------------------------------------------------------

pub fn list_saved_filters(conn: &Connection) -> rusqlite::Result<Vec<SavedFilter>> {
    let mut stmt =
        conn.prepare("SELECT id, name, params, position FROM saved_filters ORDER BY position ASC, name COLLATE NOCASE")?;
    let rows = stmt.query_map([], |r| {
        let params_str: String = r.get(2)?;
        let params = serde_json::from_str(&params_str).unwrap_or_else(|_| serde_json::json!({}));
        Ok(SavedFilter {
            id: r.get(0)?,
            name: r.get(1)?,
            params,
            position: r.get(3)?,
        })
    })?;
    rows.collect()
}

pub fn create_saved_filter(
    conn: &Connection,
    name: &str,
    params: &Value,
) -> rusqlite::Result<SavedFilter> {
    let id = new_id();
    let position: i64 = conn.query_row(
        "SELECT COALESCE(MAX(position), 0) + 1 FROM saved_filters",
        [],
        |r| r.get(0),
    )?;
    let params_str = serde_json::to_string(params).unwrap_or_else(|_| "{}".to_string());
    conn.execute(
        "INSERT INTO saved_filters (id, name, params, position, created_at) VALUES (?1, ?2, ?3, ?4, ?5)",
        params![id, name, params_str, position, now()],
    )?;
    Ok(SavedFilter {
        id,
        name: name.to_string(),
        params: params.clone(),
        position,
    })
}

pub fn remove_saved_filter(conn: &Connection, id: &str) -> rusqlite::Result<()> {
    conn.execute("DELETE FROM saved_filters WHERE id = ?1", [id])?;
    Ok(())
}

pub fn rename_saved_filter(
    conn: &Connection,
    id: &str,
    name: &str,
) -> rusqlite::Result<SavedFilter> {
    conn.execute(
        "UPDATE saved_filters SET name = ?1 WHERE id = ?2",
        params![name, id],
    )?;
    conn.query_row(
        "SELECT id, name, params, position FROM saved_filters WHERE id = ?1",
        [id],
        |r| {
            let params_str: String = r.get(2)?;
            let params =
                serde_json::from_str(&params_str).unwrap_or_else(|_| serde_json::json!({}));
            Ok(SavedFilter {
                id: r.get(0)?,
                name: r.get(1)?,
                params,
                position: r.get(3)?,
            })
        },
    )
}