#![allow(dead_code)]

use anyhow::{Context, Result};
use rusqlite::Connection;

use crate::message::{EntityKey, EntityKind, TimelineEvent, TimelineEventKind};
use crate::state::timeline::TimelineScope;

/// Internal filter resolved from a [`TimelineScope`].
///
/// Translates the user-facing scope (which uses `EntityKey` with project_id + iid)
/// into internal DB ids for efficient querying.
enum TimelineFilter {
    /// No filtering — return all events.
    All,
    /// Filter to events for a specific issue (internal DB id).
    Issue(i64),
    /// Filter to events for a specific MR (internal DB id).
    MergeRequest(i64),
    /// Filter to events by a specific actor.
    Actor(String),
}

/// Resolve a [`TimelineScope`] into a concrete [`TimelineFilter`].
fn resolve_timeline_scope(conn: &Connection, scope: &TimelineScope) -> Result<TimelineFilter> {
    match scope {
        TimelineScope::All => Ok(TimelineFilter::All),
        TimelineScope::Entity(key) => {
            let (table, kind_label) = match key.kind {
                EntityKind::Issue => ("issues", "issue"),
                EntityKind::MergeRequest => ("merge_requests", "merge request"),
            };
            let sql = format!("SELECT id FROM {table} WHERE project_id = ?1 AND iid = ?2");
            let id: i64 = conn
                .query_row(&sql, rusqlite::params![key.project_id, key.iid], |r| {
                    r.get(0)
                })
                .with_context(|| {
                    format!(
                        "resolving {kind_label} #{} in project {}",
                        key.iid, key.project_id
                    )
                })?;
            match key.kind {
                EntityKind::Issue => Ok(TimelineFilter::Issue(id)),
                EntityKind::MergeRequest => Ok(TimelineFilter::MergeRequest(id)),
            }
        }
        TimelineScope::Author(name) => Ok(TimelineFilter::Actor(name.clone())),
    }
}

/// Fetch timeline events from raw resource event tables.
///
/// Queries `issues`/`merge_requests` for Created events, plus
/// `resource_state_events`, `resource_label_events`, and
/// `resource_milestone_events` for lifecycle events. Results are sorted
/// by timestamp descending (most recent first) and truncated to `limit`.
pub fn fetch_timeline_events(
    conn: &Connection,
    scope: &TimelineScope,
    limit: usize,
) -> Result<Vec<TimelineEvent>> {
    let filter = resolve_timeline_scope(conn, scope)?;
    let mut events = Vec::new();

    // Each collector is given the full limit. After merge-sorting, we truncate
    // to `limit`. Worst case we hold 4*limit events in memory (bounded).
    collect_tl_created_events(conn, &filter, limit, &mut events)?;
    collect_tl_state_events(conn, &filter, limit, &mut events)?;
    collect_tl_label_events(conn, &filter, limit, &mut events)?;
    collect_tl_milestone_events(conn, &filter, limit, &mut events)?;

    // Sort by timestamp descending (most recent first), with stable tiebreak.
    events.sort_by(|a, b| {
        b.timestamp_ms
            .cmp(&a.timestamp_ms)
            .then_with(|| a.entity_key.kind.cmp(&b.entity_key.kind))
            .then_with(|| a.entity_key.iid.cmp(&b.entity_key.iid))
    });

    events.truncate(limit);
    Ok(events)
}

/// Collect Created events from issues and merge_requests tables.
fn collect_tl_created_events(
    conn: &Connection,
    filter: &TimelineFilter,
    limit: usize,
    events: &mut Vec<TimelineEvent>,
) -> Result<()> {
    // Issue created events.
    if !matches!(filter, TimelineFilter::MergeRequest(_)) {
        let (where_clause, mut params) = match filter {
            TimelineFilter::All => (
                "1=1".to_string(),
                Vec::<Box<dyn rusqlite::types::ToSql>>::new(),
            ),
            TimelineFilter::Issue(id) => (
                "i.id = ?1".to_string(),
                vec![Box::new(*id) as Box<dyn rusqlite::types::ToSql>],
            ),
            TimelineFilter::Actor(name) => (
                "i.author_username = ?1".to_string(),
                vec![Box::new(name.clone()) as Box<dyn rusqlite::types::ToSql>],
            ),
            TimelineFilter::MergeRequest(_) => unreachable!(),
        };

        let limit_param = params.len() + 1;
        let sql = format!(
            "SELECT i.created_at, i.iid, i.title, i.author_username, i.project_id, p.path_with_namespace
             FROM issues i
             JOIN projects p ON p.id = i.project_id
             WHERE {where_clause}
             ORDER BY i.created_at DESC
             LIMIT ?{limit_param}"
        );
        params.push(Box::new(limit as i64));

        let mut stmt = conn
            .prepare(&sql)
            .context("preparing issue created query")?;
        let param_refs: Vec<&dyn rusqlite::types::ToSql> =
            params.iter().map(AsRef::as_ref).collect();
        let rows = stmt
            .query_map(param_refs.as_slice(), |row| {
                Ok((
                    row.get::<_, i64>(0)?,
                    row.get::<_, i64>(1)?,
                    row.get::<_, Option<String>>(2)?,
                    row.get::<_, Option<String>>(3)?,
                    row.get::<_, i64>(4)?,
                    row.get::<_, String>(5)?,
                ))
            })
            .context("querying issue created events")?;

        for row in rows {
            let (created_at, iid, title, author, project_id, project_path) =
                row.context("reading issue created row")?;
            let title_str = title.as_deref().unwrap_or("(untitled)");
            events.push(TimelineEvent {
                timestamp_ms: created_at,
                entity_key: EntityKey::issue(project_id, iid),
                event_kind: TimelineEventKind::Created,
                summary: format!("Issue #{iid} created: {title_str}"),
                detail: title,
                actor: author,
                project_path,
            });
        }
    }

    // MR created events.
    if !matches!(filter, TimelineFilter::Issue(_)) {
        let (where_clause, mut params) = match filter {
            TimelineFilter::All => (
                "1=1".to_string(),
                Vec::<Box<dyn rusqlite::types::ToSql>>::new(),
            ),
            TimelineFilter::MergeRequest(id) => (
                "mr.id = ?1".to_string(),
                vec![Box::new(*id) as Box<dyn rusqlite::types::ToSql>],
            ),
            TimelineFilter::Actor(name) => (
                "mr.author_username = ?1".to_string(),
                vec![Box::new(name.clone()) as Box<dyn rusqlite::types::ToSql>],
            ),
            TimelineFilter::Issue(_) => unreachable!(),
        };

        let limit_param = params.len() + 1;
        let sql = format!(
            "SELECT mr.created_at, mr.iid, mr.title, mr.author_username, mr.project_id, p.path_with_namespace
             FROM merge_requests mr
             JOIN projects p ON p.id = mr.project_id
             WHERE {where_clause}
             ORDER BY mr.created_at DESC
             LIMIT ?{limit_param}"
        );
        params.push(Box::new(limit as i64));

        let mut stmt = conn.prepare(&sql).context("preparing MR created query")?;
        let param_refs: Vec<&dyn rusqlite::types::ToSql> =
            params.iter().map(AsRef::as_ref).collect();
        let rows = stmt
            .query_map(param_refs.as_slice(), |row| {
                Ok((
                    row.get::<_, i64>(0)?,
                    row.get::<_, i64>(1)?,
                    row.get::<_, Option<String>>(2)?,
                    row.get::<_, Option<String>>(3)?,
                    row.get::<_, i64>(4)?,
                    row.get::<_, String>(5)?,
                ))
            })
            .context("querying MR created events")?;

        for row in rows {
            let (created_at, iid, title, author, project_id, project_path) =
                row.context("reading MR created row")?;
            let title_str = title.as_deref().unwrap_or("(untitled)");
            events.push(TimelineEvent {
                timestamp_ms: created_at,
                entity_key: EntityKey::mr(project_id, iid),
                event_kind: TimelineEventKind::Created,
                summary: format!("MR !{iid} created: {title_str}"),
                detail: title,
                actor: author,
                project_path,
            });
        }
    }

    Ok(())
}

/// Helper: build WHERE clause and params for resource event tables.
///
/// Resource event tables have `issue_id` and `merge_request_id` columns
/// (exactly one is non-NULL per row), plus `actor_username`.
fn resource_event_where(filter: &TimelineFilter) -> (String, Vec<Box<dyn rusqlite::types::ToSql>>) {
    match filter {
        TimelineFilter::All => ("1=1".to_string(), Vec::new()),
        TimelineFilter::Issue(id) => (
            "e.issue_id = ?1".to_string(),
            vec![Box::new(*id) as Box<dyn rusqlite::types::ToSql>],
        ),
        TimelineFilter::MergeRequest(id) => (
            "e.merge_request_id = ?1".to_string(),
            vec![Box::new(*id) as Box<dyn rusqlite::types::ToSql>],
        ),
        TimelineFilter::Actor(name) => (
            "e.actor_username = ?1".to_string(),
            vec![Box::new(name.clone()) as Box<dyn rusqlite::types::ToSql>],
        ),
    }
}

/// Resolve a resource event row's entity to an EntityKey.
fn resolve_event_entity(
    issue_id: Option<i64>,
    mr_id: Option<i64>,
    issue_iid: Option<i64>,
    mr_iid: Option<i64>,
    issue_project_id: Option<i64>,
    mr_project_id: Option<i64>,
) -> Option<(EntityKey, i64)> {
    if let (Some(iid), Some(pid)) = (issue_iid, issue_project_id) {
        Some((EntityKey::issue(pid, iid), pid))
    } else if let (Some(iid), Some(pid)) = (mr_iid, mr_project_id) {
        Some((EntityKey::mr(pid, iid), pid))
    } else {
        // Orphaned event — entity was deleted.
        let _ = (issue_id, mr_id); // suppress unused warnings
        None
    }
}

/// Collect state change events from `resource_state_events`.
fn collect_tl_state_events(
    conn: &Connection,
    filter: &TimelineFilter,
    limit: usize,
    events: &mut Vec<TimelineEvent>,
) -> Result<()> {
    let (where_clause, mut params) = resource_event_where(filter);
    let limit_param = params.len() + 1;

    let sql = format!(
        "SELECT e.created_at, e.state, e.actor_username,
                e.issue_id, e.merge_request_id,
                i.iid, mr.iid, i.project_id, mr.project_id,
                COALESCE(pi.path_with_namespace, pm.path_with_namespace) AS project_path
         FROM resource_state_events e
         LEFT JOIN issues i ON i.id = e.issue_id
         LEFT JOIN merge_requests mr ON mr.id = e.merge_request_id
         LEFT JOIN projects pi ON pi.id = i.project_id
         LEFT JOIN projects pm ON pm.id = mr.project_id
         WHERE {where_clause}
         ORDER BY e.created_at DESC
         LIMIT ?{limit_param}"
    );
    params.push(Box::new(limit as i64));

    let mut stmt = conn.prepare(&sql).context("preparing state events query")?;
    let param_refs: Vec<&dyn rusqlite::types::ToSql> = params.iter().map(AsRef::as_ref).collect();
    let rows = stmt
        .query_map(param_refs.as_slice(), |row| {
            Ok((
                row.get::<_, i64>(0)?,
                row.get::<_, String>(1)?,
                row.get::<_, Option<String>>(2)?,
                row.get::<_, Option<i64>>(3)?,
                row.get::<_, Option<i64>>(4)?,
                row.get::<_, Option<i64>>(5)?,
                row.get::<_, Option<i64>>(6)?,
                row.get::<_, Option<i64>>(7)?,
                row.get::<_, Option<i64>>(8)?,
                row.get::<_, Option<String>>(9)?,
            ))
        })
        .context("querying state events")?;

    for row in rows {
        let (
            created_at,
            state,
            actor,
            issue_id,
            mr_id,
            issue_iid,
            mr_iid,
            issue_pid,
            mr_pid,
            project_path,
        ) = row.context("reading state event row")?;

        let Some((entity_key, _pid)) =
            resolve_event_entity(issue_id, mr_id, issue_iid, mr_iid, issue_pid, mr_pid)
        else {
            continue;
        };

        let (event_kind, summary) = if state == "merged" {
            (
                TimelineEventKind::Merged,
                format!("MR !{} merged", entity_key.iid),
            )
        } else {
            (
                TimelineEventKind::StateChanged,
                format!("State changed to {state}"),
            )
        };

        events.push(TimelineEvent {
            timestamp_ms: created_at,
            entity_key,
            event_kind,
            summary,
            detail: Some(state),
            actor,
            project_path: project_path.unwrap_or_default(),
        });
    }

    Ok(())
}

/// Collect label change events from `resource_label_events`.
fn collect_tl_label_events(
    conn: &Connection,
    filter: &TimelineFilter,
    limit: usize,
    events: &mut Vec<TimelineEvent>,
) -> Result<()> {
    let (where_clause, mut params) = resource_event_where(filter);
    let limit_param = params.len() + 1;

    let sql = format!(
        "SELECT e.created_at, e.action, e.label_name, e.actor_username,
                e.issue_id, e.merge_request_id,
                i.iid, mr.iid, i.project_id, mr.project_id,
                COALESCE(pi.path_with_namespace, pm.path_with_namespace) AS project_path
         FROM resource_label_events e
         LEFT JOIN issues i ON i.id = e.issue_id
         LEFT JOIN merge_requests mr ON mr.id = e.merge_request_id
         LEFT JOIN projects pi ON pi.id = i.project_id
         LEFT JOIN projects pm ON pm.id = mr.project_id
         WHERE {where_clause}
         ORDER BY e.created_at DESC
         LIMIT ?{limit_param}"
    );
    params.push(Box::new(limit as i64));

    let mut stmt = conn.prepare(&sql).context("preparing label events query")?;
    let param_refs: Vec<&dyn rusqlite::types::ToSql> = params.iter().map(AsRef::as_ref).collect();
    let rows = stmt
        .query_map(param_refs.as_slice(), |row| {
            Ok((
                row.get::<_, i64>(0)?,
                row.get::<_, String>(1)?,
                row.get::<_, String>(2)?,
                row.get::<_, Option<String>>(3)?,
                row.get::<_, Option<i64>>(4)?,
                row.get::<_, Option<i64>>(5)?,
                row.get::<_, Option<i64>>(6)?,
                row.get::<_, Option<i64>>(7)?,
                row.get::<_, Option<i64>>(8)?,
                row.get::<_, Option<i64>>(9)?,
                row.get::<_, Option<String>>(10)?,
            ))
        })
        .context("querying label events")?;

    for row in rows {
        let (
            created_at,
            action,
            label_name,
            actor,
            issue_id,
            mr_id,
            issue_iid,
            mr_iid,
            issue_pid,
            mr_pid,
            project_path,
        ) = row.context("reading label event row")?;

        let Some((entity_key, _pid)) =
            resolve_event_entity(issue_id, mr_id, issue_iid, mr_iid, issue_pid, mr_pid)
        else {
            continue;
        };

        let (event_kind, summary) = match action.as_str() {
            "add" => (
                TimelineEventKind::LabelAdded,
                format!("Label added: {label_name}"),
            ),
            "remove" => (
                TimelineEventKind::LabelRemoved,
                format!("Label removed: {label_name}"),
            ),
            _ => continue,
        };

        events.push(TimelineEvent {
            timestamp_ms: created_at,
            entity_key,
            event_kind,
            summary,
            detail: Some(label_name),
            actor,
            project_path: project_path.unwrap_or_default(),
        });
    }

    Ok(())
}

/// Collect milestone change events from `resource_milestone_events`.
fn collect_tl_milestone_events(
    conn: &Connection,
    filter: &TimelineFilter,
    limit: usize,
    events: &mut Vec<TimelineEvent>,
) -> Result<()> {
    let (where_clause, mut params) = resource_event_where(filter);
    let limit_param = params.len() + 1;

    let sql = format!(
        "SELECT e.created_at, e.action, e.milestone_title, e.actor_username,
                e.issue_id, e.merge_request_id,
                i.iid, mr.iid, i.project_id, mr.project_id,
                COALESCE(pi.path_with_namespace, pm.path_with_namespace) AS project_path
         FROM resource_milestone_events e
         LEFT JOIN issues i ON i.id = e.issue_id
         LEFT JOIN merge_requests mr ON mr.id = e.merge_request_id
         LEFT JOIN projects pi ON pi.id = i.project_id
         LEFT JOIN projects pm ON pm.id = mr.project_id
         WHERE {where_clause}
         ORDER BY e.created_at DESC
         LIMIT ?{limit_param}"
    );
    params.push(Box::new(limit as i64));

    let mut stmt = conn
        .prepare(&sql)
        .context("preparing milestone events query")?;
    let param_refs: Vec<&dyn rusqlite::types::ToSql> = params.iter().map(AsRef::as_ref).collect();
    let rows = stmt
        .query_map(param_refs.as_slice(), |row| {
            Ok((
                row.get::<_, i64>(0)?,
                row.get::<_, String>(1)?,
                row.get::<_, String>(2)?,
                row.get::<_, Option<String>>(3)?,
                row.get::<_, Option<i64>>(4)?,
                row.get::<_, Option<i64>>(5)?,
                row.get::<_, Option<i64>>(6)?,
                row.get::<_, Option<i64>>(7)?,
                row.get::<_, Option<i64>>(8)?,
                row.get::<_, Option<i64>>(9)?,
                row.get::<_, Option<String>>(10)?,
            ))
        })
        .context("querying milestone events")?;

    for row in rows {
        let (
            created_at,
            action,
            milestone_title,
            actor,
            issue_id,
            mr_id,
            issue_iid,
            mr_iid,
            issue_pid,
            mr_pid,
            project_path,
        ) = row.context("reading milestone event row")?;

        let Some((entity_key, _pid)) =
            resolve_event_entity(issue_id, mr_id, issue_iid, mr_iid, issue_pid, mr_pid)
        else {
            continue;
        };

        let (event_kind, summary) = match action.as_str() {
            "add" => (
                TimelineEventKind::MilestoneSet,
                format!("Milestone set: {milestone_title}"),
            ),
            "remove" => (
                TimelineEventKind::MilestoneRemoved,
                format!("Milestone removed: {milestone_title}"),
            ),
            _ => continue,
        };

        events.push(TimelineEvent {
            timestamp_ms: created_at,
            entity_key,
            event_kind,
            summary,
            detail: Some(milestone_title),
            actor,
            project_path: project_path.unwrap_or_default(),
        });
    }

    Ok(())
}

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

    /// Create the minimal schema needed for timeline queries.
    fn create_dashboard_schema(conn: &Connection) {
        conn.execute_batch(
            "
            CREATE TABLE projects (
                id INTEGER PRIMARY KEY,
                gitlab_project_id INTEGER UNIQUE NOT NULL,
                path_with_namespace TEXT NOT NULL
            );
            CREATE TABLE issues (
                id INTEGER PRIMARY KEY,
                gitlab_id INTEGER UNIQUE NOT NULL,
                project_id INTEGER NOT NULL,
                iid INTEGER NOT NULL,
                title TEXT,
                state TEXT NOT NULL,
                author_username TEXT,
                created_at INTEGER NOT NULL,
                updated_at INTEGER NOT NULL,
                last_seen_at INTEGER NOT NULL
            );
            CREATE TABLE merge_requests (
                id INTEGER PRIMARY KEY,
                gitlab_id INTEGER UNIQUE NOT NULL,
                project_id INTEGER NOT NULL,
                iid INTEGER NOT NULL,
                title TEXT,
                state TEXT,
                author_username TEXT,
                created_at INTEGER,
                updated_at INTEGER,
                last_seen_at INTEGER NOT NULL
            );
        ",
        )
        .expect("create dashboard schema");
    }

    fn insert_issue(conn: &Connection, iid: i64, state: &str, updated_at: i64) {
        conn.execute(
            "INSERT INTO issues (gitlab_id, project_id, iid, title, state, created_at, updated_at, last_seen_at)
             VALUES (?1, 1, ?2, ?3, ?4, ?5, ?5, ?5)",
            rusqlite::params![iid * 100, iid, format!("Issue {iid}"), state, updated_at],
        )
        .expect("insert issue");
    }

    fn insert_mr(conn: &Connection, iid: i64, state: &str, updated_at: i64) {
        conn.execute(
            "INSERT INTO merge_requests (gitlab_id, project_id, iid, title, state, created_at, updated_at, last_seen_at)
             VALUES (?1, 1, ?2, ?3, ?4, ?5, ?5, ?5)",
            rusqlite::params![iid * 100 + 50, iid, format!("MR {iid}"), state, updated_at],
        )
        .expect("insert mr");
    }

    /// Add resource event tables to an existing schema.
    fn add_resource_event_tables(conn: &Connection) {
        conn.execute_batch(
            "
            CREATE TABLE IF NOT EXISTS resource_state_events (
                id INTEGER PRIMARY KEY,
                gitlab_id INTEGER NOT NULL,
                project_id INTEGER NOT NULL,
                issue_id INTEGER,
                merge_request_id INTEGER,
                state TEXT NOT NULL,
                actor_gitlab_id INTEGER,
                actor_username TEXT,
                created_at INTEGER NOT NULL,
                source_commit TEXT,
                source_merge_request_iid INTEGER
            );
            CREATE TABLE IF NOT EXISTS resource_label_events (
                id INTEGER PRIMARY KEY,
                gitlab_id INTEGER NOT NULL,
                project_id INTEGER NOT NULL,
                issue_id INTEGER,
                merge_request_id INTEGER,
                action TEXT NOT NULL,
                label_name TEXT NOT NULL,
                actor_gitlab_id INTEGER,
                actor_username TEXT,
                created_at INTEGER NOT NULL
            );
            CREATE TABLE IF NOT EXISTS resource_milestone_events (
                id INTEGER PRIMARY KEY,
                gitlab_id INTEGER NOT NULL,
                project_id INTEGER NOT NULL,
                issue_id INTEGER,
                merge_request_id INTEGER,
                action TEXT NOT NULL,
                milestone_title TEXT NOT NULL,
                milestone_id INTEGER,
                actor_gitlab_id INTEGER,
                actor_username TEXT,
                created_at INTEGER NOT NULL
            );
            ",
        )
        .expect("create resource event tables");
    }

    /// Create a full timeline test schema (dashboard schema + resource events).
    fn create_timeline_schema(conn: &Connection) {
        create_dashboard_schema(conn);
        add_resource_event_tables(conn);
        // Insert a project for test entities.
        conn.execute(
            "INSERT INTO projects (id, gitlab_project_id, path_with_namespace) VALUES (1, 100, 'group/project')",
            [],
        )
        .expect("insert test project");
    }

    fn insert_state_event(
        conn: &Connection,
        gitlab_id: i64,
        issue_id: Option<i64>,
        mr_id: Option<i64>,
        state: &str,
        actor: &str,
        created_at: i64,
    ) {
        conn.execute(
            "INSERT INTO resource_state_events (gitlab_id, project_id, issue_id, merge_request_id, state, actor_username, created_at)
             VALUES (?1, 1, ?2, ?3, ?4, ?5, ?6)",
            rusqlite::params![gitlab_id, issue_id, mr_id, state, actor, created_at],
        )
        .expect("insert state event");
    }

    #[allow(clippy::too_many_arguments)]
    fn insert_label_event(
        conn: &Connection,
        gitlab_id: i64,
        issue_id: Option<i64>,
        mr_id: Option<i64>,
        action: &str,
        label: &str,
        actor: &str,
        created_at: i64,
    ) {
        conn.execute(
            "INSERT INTO resource_label_events (gitlab_id, project_id, issue_id, merge_request_id, action, label_name, actor_username, created_at)
             VALUES (?1, 1, ?2, ?3, ?4, ?5, ?6, ?7)",
            rusqlite::params![gitlab_id, issue_id, mr_id, action, label, actor, created_at],
        )
        .expect("insert label event");
    }

    #[test]
    fn test_fetch_timeline_scoped() {
        let conn = Connection::open_in_memory().unwrap();
        create_timeline_schema(&conn);

        // Create two issues.
        let now = 1_700_000_000_000_i64;
        insert_issue(&conn, 1, "opened", now - 100_000);
        insert_issue(&conn, 2, "opened", now - 50_000);

        // Get internal IDs.
        let issue1_id: i64 = conn
            .query_row("SELECT id FROM issues WHERE iid = 1", [], |r| r.get(0))
            .unwrap();
        let issue2_id: i64 = conn
            .query_row("SELECT id FROM issues WHERE iid = 2", [], |r| r.get(0))
            .unwrap();

        // State events: issue 1 closed, issue 2 label added.
        insert_state_event(
            &conn,
            1,
            Some(issue1_id),
            None,
            "closed",
            "alice",
            now - 80_000,
        );
        insert_label_event(
            &conn,
            2,
            Some(issue2_id),
            None,
            "add",
            "bug",
            "bob",
            now - 30_000,
        );

        // Fetch scoped to issue 1.
        let scope = TimelineScope::Entity(EntityKey::issue(1, 1));
        let events = fetch_timeline_events(&conn, &scope, 100).unwrap();

        // Should only have issue 1's events: Created + StateChanged.
        assert_eq!(events.len(), 2);
        for event in &events {
            assert_eq!(event.entity_key.iid, 1, "All events should be for issue #1");
        }
        // Most recent first.
        assert!(events[0].timestamp_ms >= events[1].timestamp_ms);
    }

    #[test]
    fn test_fetch_timeline_all_scope() {
        let conn = Connection::open_in_memory().unwrap();
        create_timeline_schema(&conn);

        let now = 1_700_000_000_000_i64;
        insert_issue(&conn, 1, "opened", now - 100_000);
        insert_issue(&conn, 2, "opened", now - 50_000);

        let events = fetch_timeline_events(&conn, &TimelineScope::All, 100).unwrap();

        // Should have Created events for both issues.
        assert_eq!(events.len(), 2);
    }

    #[test]
    fn test_fetch_timeline_author_scope() {
        let conn = Connection::open_in_memory().unwrap();
        create_timeline_schema(&conn);

        let now = 1_700_000_000_000_i64;
        insert_issue(&conn, 1, "opened", now - 100_000); // default: no author_username in insert_issue

        let issue1_id: i64 = conn
            .query_row("SELECT id FROM issues WHERE iid = 1", [], |r| r.get(0))
            .unwrap();

        // State events by different actors.
        insert_state_event(
            &conn,
            1,
            Some(issue1_id),
            None,
            "closed",
            "alice",
            now - 80_000,
        );
        insert_state_event(
            &conn,
            2,
            Some(issue1_id),
            None,
            "reopened",
            "bob",
            now - 60_000,
        );

        let scope = TimelineScope::Author("alice".into());
        let events = fetch_timeline_events(&conn, &scope, 100).unwrap();

        // Should only get alice's state event (Created events don't have author set via insert_issue).
        assert!(events.iter().all(|e| e.actor.as_deref() == Some("alice")));
    }

    #[test]
    fn test_fetch_timeline_respects_limit() {
        let conn = Connection::open_in_memory().unwrap();
        create_timeline_schema(&conn);

        let now = 1_700_000_000_000_i64;
        for i in 1..=10 {
            insert_issue(&conn, i, "opened", now - (i * 10_000));
        }

        let events = fetch_timeline_events(&conn, &TimelineScope::All, 3).unwrap();
        assert_eq!(events.len(), 3);
    }

    #[test]
    fn test_fetch_timeline_sorted_most_recent_first() {
        let conn = Connection::open_in_memory().unwrap();
        create_timeline_schema(&conn);

        let now = 1_700_000_000_000_i64;
        insert_issue(&conn, 1, "opened", now - 200_000);
        insert_issue(&conn, 2, "opened", now - 100_000);
        insert_issue(&conn, 3, "opened", now - 300_000);

        let events = fetch_timeline_events(&conn, &TimelineScope::All, 100).unwrap();

        for window in events.windows(2) {
            assert!(
                window[0].timestamp_ms >= window[1].timestamp_ms,
                "Events should be sorted most-recent-first"
            );
        }
    }

    #[test]
    fn test_fetch_timeline_state_merged_is_merged_kind() {
        let conn = Connection::open_in_memory().unwrap();
        create_timeline_schema(&conn);

        let now = 1_700_000_000_000_i64;
        insert_mr(&conn, 1, "merged", now - 100_000);

        let mr_id: i64 = conn
            .query_row("SELECT id FROM merge_requests WHERE iid = 1", [], |r| {
                r.get(0)
            })
            .unwrap();

        insert_state_event(&conn, 1, None, Some(mr_id), "merged", "alice", now - 50_000);

        let scope = TimelineScope::Entity(EntityKey::mr(1, 1));
        let events = fetch_timeline_events(&conn, &scope, 100).unwrap();

        let merged_events: Vec<_> = events
            .iter()
            .filter(|e| e.event_kind == TimelineEventKind::Merged)
            .collect();
        assert_eq!(merged_events.len(), 1);
        assert_eq!(merged_events[0].summary, "MR !1 merged");
    }

    #[test]
    fn test_fetch_timeline_empty_db() {
        let conn = Connection::open_in_memory().unwrap();
        create_timeline_schema(&conn);

        let events = fetch_timeline_events(&conn, &TimelineScope::All, 100).unwrap();
        assert!(events.is_empty());
    }
}