//! Read-side views of the true-instant date contract (ADR-0001).
//!
//! [`crate::date_resolver`] is the ingest-side counterpart: it *writes* the
//! `(date_utc, camera_offset_minutes, date_taken_tz_source)` triple. This
//! module is what *reads* it. For a row — converted or not yet — it answers:
//!
//! 1. **What true instant does the row name?** — [`row_true_instant`].
//!    Anchors time-window queries (SMS messages, location history, calendar
//!    events) with zero offset arithmetic: the window is centered on the
//!    instant, never on a wall clock.
//! 2. **What wall clock does the owner see?** — [`row_display_wall`].
//!    The date insight prompts tell the model (camera wall clock when the
//!    row carries an offset, display-zone rendering when it doesn't). Must
//!    equal the wall the metadata endpoint reports, so prompt and UI agree.
//! 3. **Which owner day does the row land on?** — [`row_display_day`].
//!    The grouping rule for memories buckets and reels: a photo taken in
//!    Japan at 21:00 JST lands in the *owner's* day, not the camera's.
//!
//! Converted rows read the new triple directly. Unconverted rows (the
//! `backfill_utc_dates` drain has not reached them yet) fall back to the
//! legacy `date_taken` under its per-source convention (ADR-0001):
//!
//! | source | legacy holds |
//! |---|---|
//! | `exif` | camera wall clock, reinterpreted as UTC |
//! | `exiftool` (video) | the container's UTC-rendered naive, rendered in the server zone |
//! | `exiftool` (image) | camera wall clock, rendered in the server zone |
//! | `filename` (wall patterns) | wall clock, reinterpreted as UTC |
//! | `filename` (unix-timestamp) | a true instant |
//! | `fs_time` | a true instant |
//! | `manual` | the display-zone wall the operator picked, reinterpreted as UTC |
//!
//! so mixed rows mid-drain still group into the right day and the insight
//! prompts stay correct row-by-row as the drain converts.

use chrono::{NaiveDate, NaiveDateTime, TimeZone};
use chrono_tz::Tz;

use crate::camera_tz;
use crate::database::models::ImageExif;

/// Best-effort true instant (unix seconds) the row names.
///
/// `date_utc` when the drain has converted the row; otherwise derived from
/// the legacy value under its per-source convention. `server_zone` is the
/// fallback rung the drain would use without offset-tag or GPS evidence
/// (the camera was probably carried in the operator's zone); `display_zone`
/// interprets manual rows.
pub fn row_true_instant(row: &ImageExif, display_zone: Tz, server_zone: Option<Tz>) -> Option<i64> {
    let legacy = row.date_taken?;

    // Converted rows name their instant directly.
    if let Some(utc) = row.date_utc {
        return Some(utc);
    }

    match row.date_taken_source.as_deref() {
        // Camera wall reinterpreted as UTC: the wall is the legacy value
        // itself; the instant is that wall in the assumed zone.
        Some("exif") => wall_in_zone(legacy, server_zone),

        // exiftool rendered a naive string in the server zone. Videos hold
        // the container's UTC-rendered creation time (a true instant behind
        // one server-zone render); photos hold the camera wall.
        Some("exiftool") => {
            if crate::file_types::is_video_file(std::path::Path::new(&row.file_path)) {
                // legacy = server.render(naive_utc) → recover naive_utc and
                // read it back as UTC.
                let naive = render_in_zone_fallback(legacy, server_zone);
                Some(naive.and_utc().timestamp())
            } else {
                // legacy = server.render(wall); the instant is that wall in
                // the server zone, which is `legacy` by construction.
                Some(legacy)
            }
        }

        // Filename class: wall patterns name a wall clock, the
        // unix-timestamp pattern names a true instant directly.
        Some("filename") => match crate::memories::match_filename_date(&row.file_path) {
            Some(m) if matches!(m.date, crate::memories::FilenameDate::Wall(_)) => {
                wall_in_zone(legacy, server_zone)
            }
            _ => Some(legacy),
        },

        Some("fs_time") => Some(legacy),

        // The operator picked a display-zone wall; interpret it there.
        Some("manual") => camera_tz::manual_date_resolution(Some(display_zone.name()), legacy)
            .map(|(instant, _)| instant),

        // Unknown / absent source: treat the legacy value as a true instant
        // (the most common convention) rather than a wall clock.
        _ => Some(legacy),
    }
}

/// The wall clock the owner sees for this row — camera wall when the row
/// carries an offset (a Japan photo shows the Japan wall), display-zone
/// rendering when it doesn't. Unconverted rows use their per-source
/// convention (see module docs).
pub fn row_display_wall(
    row: &ImageExif,
    display_zone: Tz,
    server_zone: Option<Tz>,
) -> Option<NaiveDateTime> {
    if let Some(utc) = row.date_utc {
        // Converted: wall = instant + camera offset (offset = local − UTC).
        if let Some(offset_min) = row.camera_offset_minutes {
            let wall = chrono::DateTime::from_timestamp(utc + offset_min as i64 * 60, 0)?;
            return Some(wall.naive_utc());
        }
        return render_in_zone_opt(utc, display_zone);
    }

    let legacy = row.date_taken?;
    match row.date_taken_source.as_deref() {
        // The wall clock itself, stored as naive-as-UTC.
        Some("exif") => Some(legacy_as_naive(legacy)),

        Some("exiftool") => {
            if crate::file_types::is_video_file(std::path::Path::new(&row.file_path)) {
                // No camera wall exists for a container; show the owner's
                // zone rendering of the recovered instant.
                let naive = render_in_zone_fallback(legacy, server_zone);
                let instant = naive.and_utc().timestamp();
                render_in_zone_opt(instant, display_zone)
            } else {
                // The camera wall, recovered from the server-zone render.
                Some(render_in_zone_fallback(legacy, server_zone))
            }
        }

        Some("filename") => match crate::memories::match_filename_date(&row.file_path) {
            Some(m) if matches!(m.date, crate::memories::FilenameDate::Wall(_)) => {
                Some(legacy_as_naive(legacy))
            }
            _ => render_in_zone_opt(legacy, display_zone),
        },

        Some("fs_time") => render_in_zone_opt(legacy, display_zone),

        Some("manual") => Some(legacy_as_naive(legacy)),

        _ => render_in_zone_opt(legacy, display_zone),
    }
}

/// The true instant a filename-class date names, for callers that fall
/// back to the filename when the row carries no date at all: wall patterns
/// are read in `server_zone` (the zone the camera was probably in),
/// unix-timestamp patterns are true instants outright.
pub fn filename_true_instant(
    fd: &crate::memories::FilenameDate,
    server_zone: Option<Tz>,
) -> Option<i64> {
    match fd {
        crate::memories::FilenameDate::Utc(dt) => Some(dt.timestamp()),
        crate::memories::FilenameDate::Wall(wall) => match server_zone {
            Some(z) => z
                .from_local_datetime(wall)
                .single()
                .map(|dt| dt.timestamp()),
            None => Some(wall.and_utc().timestamp()),
        },
    }
}

/// The owner's calendar day for this row: the day of the true instant in
/// the owner's display zone. This is the grouping key — a photo taken in
/// Japan at 21:00 JST lands in the owner's day, not the camera's.
pub fn row_display_day(
    row: &ImageExif,
    display_zone: Tz,
    server_zone: Option<Tz>,
) -> Option<NaiveDate> {
    let instant = row_true_instant(row, display_zone, server_zone)?;
    Some(
        display_zone
            .timestamp_opt(instant, 0)
            .single()?
            .date_naive(),
    )
}

/// Wire format for a wall clock: naive ISO-8601, no zone designator
/// (`2018-09-29T14:00:00`). Clients render it verbatim — no zone math —
/// so the UI shows exactly the wall [`row_display_wall`] computed and
/// insight prompts use (ADR-0001: consumers never re-anchor).
pub fn format_wall_clock(wall: NaiveDateTime) -> String {
    wall.format("%Y-%m-%dT%H:%M:%S").to_string()
}

/// The owner's display zone for a request: prefs `display_tz`, else the
/// app default (never fails — an unreadable prefs row is the default).
pub fn owner_display_zone(
    prefs_dao: &std::sync::Mutex<Box<dyn crate::database::UserAiPrefsDao>>,
    context: &opentelemetry::Context,
) -> Tz {
    use std::str::FromStr;
    let stored = prefs_dao
        .lock()
        .ok()
        .and_then(|mut dao| dao.get_prefs(context).ok().flatten())
        .and_then(|p| p.display_tz);
    Tz::from_str(&camera_tz::display_zone_for(stored.as_deref()))
        .unwrap_or(chrono_tz::Tz::America__New_York)
}

/// [`row_display_wall`] in wire format.
pub fn row_wall_clock(
    row: &ImageExif,
    display_zone: Tz,
    server_zone: Option<Tz>,
) -> Option<String> {
    row_display_wall(row, display_zone, server_zone).map(format_wall_clock)
}

/// Wall clock for a file that may have no `image_exif` row yet (not yet
/// ingested, or excluded): the row's wall when it has one, else the
/// filename-class date (a wall pattern *is* the wall; a unix-timestamp
/// pattern renders in the display zone), else the file's earliest
/// filesystem time rendered in the display zone. The same precedence the
/// ingest waterfall applies, so the value doesn't jump once the row lands.
pub fn file_wall_clock(
    row: Option<&ImageExif>,
    rel_path: &str,
    fs_earliest: Option<i64>,
    display_zone: Tz,
    server_zone: Option<Tz>,
) -> Option<String> {
    if let Some(wall) = row.and_then(|r| row_display_wall(r, display_zone, server_zone)) {
        return Some(format_wall_clock(wall));
    }
    let wall = match crate::memories::extract_date_from_filename(rel_path) {
        Some(crate::memories::FilenameDate::Wall(wall)) => Some(wall),
        Some(crate::memories::FilenameDate::Utc(dt)) => {
            render_in_zone_opt(dt.timestamp(), display_zone)
        }
        None => fs_earliest.and_then(|t| render_in_zone_opt(t, display_zone)),
    };
    wall.map(format_wall_clock)
}

/// Render a unix instant as a naive wall in `zone`.
fn render_in_zone_opt(instant: i64, zone: Tz) -> Option<NaiveDateTime> {
    zone.timestamp_opt(instant, 0)
        .single()
        .map(|dt| dt.naive_local())
}

/// Render a unix instant as a naive wall in `zone`, falling back to the
/// naive-as-UTC reading when the zone is unknown.
fn render_in_zone_fallback(instant: i64, zone: Option<Tz>) -> NaiveDateTime {
    match zone {
        Some(z) => z
            .timestamp_opt(instant, 0)
            .single()
            .map(|dt| dt.naive_local())
            .unwrap_or_else(|| legacy_as_naive(instant)),
        None => legacy_as_naive(instant),
    }
}

/// Read a stored wall-as-UTC epoch back as its naive wall.
fn legacy_as_naive(legacy: i64) -> NaiveDateTime {
    chrono::DateTime::from_timestamp(legacy, 0)
        .expect("valid epoch")
        .naive_utc()
}

/// The true instant of a wall clock assumed to have been read in `zone`;
/// naive-as-UTC when the zone is unknown.
fn wall_in_zone(legacy_wall_epoch: i64, zone: Option<Tz>) -> Option<i64> {
    let wall = legacy_as_naive(legacy_wall_epoch);
    match zone {
        Some(z) => z
            .from_local_datetime(&wall)
            .single()
            .map(|dt| dt.timestamp()),
        None => Some(legacy_wall_epoch),
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use chrono::{NaiveDate, TimeZone};
    use chrono_tz::Tz;

    fn ny() -> Tz {
        Tz::America__New_York
    }

    /// Build a minimal `ImageExif` row for date-field tests.
    fn row(
        path: &str,
        date_taken: Option<i64>,
        source: Option<&str>,
        date_utc: Option<i64>,
        offset: Option<i32>,
    ) -> ImageExif {
        ImageExif {
            id: 1,
            library_id: 1,
            file_path: path.to_string(),
            camera_make: None,
            camera_model: None,
            lens_model: None,
            width: None,
            height: None,
            orientation: None,
            gps_latitude: None,
            gps_longitude: None,
            gps_altitude: None,
            focal_length: None,
            aperture: None,
            shutter_speed: None,
            iso: None,
            date_taken,
            created_time: 0,
            last_modified: 0,
            content_hash: None,
            size_bytes: None,
            phash_64: None,
            dhash_64: None,
            duplicate_of_hash: None,
            duplicate_decided_at: None,
            date_taken_source: source.map(str::to_string),
            original_date_taken: None,
            original_date_taken_source: None,
            clip_embedding: None,
            clip_model_version: None,
            date_utc,
            camera_offset_minutes: offset,
            date_taken_tz_source: None,
            original_date_utc: None,
            original_camera_offset_minutes: None,
            original_date_taken_tz_source: None,
        }
    }

    fn utc_epoch(y: i32, mo: u32, d: u32, h: u32, mi: u32) -> i64 {
        NaiveDate::from_ymd_opt(y, mo, d)
            .unwrap()
            .and_hms_opt(h, mi, 0)
            .unwrap()
            .and_utc()
            .timestamp()
    }

    /// The AC-3 fixture: three rows naming the same true instant
    /// (2024-07-05 01:30 UTC = 2024-07-04 21:30 EDT — the owner's day is
    /// July 4), one per source convention. Server zone = display zone = NY.
    fn ac3_fixtures() -> (ImageExif, ImageExif, ImageExif, i64) {
        let instant = utc_epoch(2024, 7, 5, 1, 30);
        let exif = row(
            "photos/IMG_1234.jpg",
            Some(utc_epoch(2024, 7, 4, 21, 30)), // wall 21:30 as naive-as-UTC
            Some("exif"),
            None,
            None,
        );
        let fs = row(
            "photos/scan.pdf.jpg",
            Some(instant),
            Some("fs_time"),
            None,
            None,
        );
        // Container: exiftool rendered the UTC naive "2024-07-05 01:30" in
        // the server zone (EDT) → instant + 4h.
        let container = row(
            "videos/clip.mp4",
            Some(instant + 4 * 3600),
            Some("exiftool"),
            None,
            None,
        );
        (exif, fs, container, instant)
    }

    #[test]
    fn ac3_same_instant_three_sources_group_into_one_owner_day() {
        let (exif, fs, container, instant) = ac3_fixtures();
        let d = ny();

        for (name, r) in [
            ("exif", &exif),
            ("fs_time", &fs),
            ("exiftool-video", &container),
        ] {
            assert_eq!(
                row_true_instant(r, d, Some(d)),
                Some(instant),
                "{name}: wrong instant"
            );
            assert_eq!(
                row_display_day(r, d, Some(d)).map(|dt| dt.to_string()),
                Some("2024-07-04".to_string()),
                "{name}: wrong owner day"
            );
        }
    }

    #[test]
    fn ac3_old_client_offset_grouping_would_have_misplaced_the_container() {
        // Regression guard for the double-shift: rendering the container's
        // legacy value in the client (NY) offset lands on July 5, a day
        // after the owner's.
        let (_, _, container, _) = ac3_fixtures();
        let legacy = container.date_taken.unwrap();
        let old_grouping_day = chrono::FixedOffset::east_opt(-4 * 3600)
            .unwrap()
            .timestamp_opt(legacy, 0)
            .single()
            .unwrap()
            .date_naive();
        assert_eq!(old_grouping_day.to_string(), "2024-07-05");
    }

    #[test]
    fn converted_row_with_offset_shows_camera_wall() {
        // Japan (UTC+9) photo: instant 2024-07-05 12:00 UTC, wall 21:00 JST.
        let r = row(
            "japan/IMG_0001.jpg",
            Some(utc_epoch(2024, 7, 5, 21, 0)),
            Some("exif"),
            Some(utc_epoch(2024, 7, 5, 12, 0)),
            Some(9 * 60),
        );
        let d = ny();
        assert_eq!(
            row_display_wall(&r, d, Some(d)).map(|w| w.to_string()),
            Some("2024-07-05 21:00:00".to_string())
        );
        // ...but groups into the owner's (NY) day: 12:00 UTC = 08:00 EDT.
        assert_eq!(
            row_display_day(&r, d, Some(d)).map(|dt| dt.to_string()),
            Some("2024-07-05".to_string())
        );
        assert_eq!(
            row_true_instant(&r, d, Some(d)),
            Some(utc_epoch(2024, 7, 5, 12, 0))
        );
    }

    #[test]
    fn converted_row_without_offset_renders_in_display_zone() {
        // fs_time row, no camera offset: wall = display-zone rendering.
        // 2024-01-15 04:30 UTC = 23:30 Jan 14 EST (DST-aware).
        let r = row(
            "fs/IMG_9.jpg",
            Some(utc_epoch(2024, 1, 15, 4, 30)),
            Some("fs_time"),
            Some(utc_epoch(2024, 1, 15, 4, 30)),
            None,
        );
        let d = ny();
        assert_eq!(
            row_display_wall(&r, d, Some(d)).map(|w| w.to_string()),
            Some("2024-01-14 23:30:00".to_string())
        );
        assert_eq!(
            row_display_day(&r, d, Some(d)).map(|dt| dt.to_string()),
            Some("2024-01-14".to_string())
        );
    }

    #[test]
    fn unconverted_exif_wall_is_the_legacy_naive_and_instant_uses_server_zone() {
        // Wall 2024-01-15 21:30 (EST era), legacy = 21:30 naive-as-UTC.
        // Instant = 21:30 EST = 2024-01-16 02:30 UTC (DST-aware, not +4h).
        let r = row(
            "photo.jpg",
            Some(utc_epoch(2024, 1, 15, 21, 30)),
            Some("exif"),
            None,
            None,
        );
        let d = ny();
        assert_eq!(
            row_display_wall(&r, d, Some(d)).map(|w| w.to_string()),
            Some("2024-01-15 21:30:00".to_string())
        );
        assert_eq!(
            row_true_instant(&r, d, Some(d)),
            Some(utc_epoch(2024, 1, 16, 2, 30))
        );
        assert_eq!(
            row_display_day(&r, d, Some(d)).map(|dt| dt.to_string()),
            Some("2024-01-15".to_string())
        );
    }

    #[test]
    fn unconverted_exiftool_photo_wall_is_server_zone_render() {
        // Camera wall 2024-07-04 12:00 rendered in server zone EDT →
        // legacy = 16:00 UTC. The wall comes back out the other side.
        let r = row(
            "raw/IMG_5.NEF",
            Some(utc_epoch(2024, 7, 4, 16, 0)),
            Some("exiftool"),
            None,
            None,
        );
        let d = ny();
        assert_eq!(
            row_display_wall(&r, d, Some(d)).map(|w| w.to_string()),
            Some("2024-07-04 12:00:00".to_string())
        );
        // Instant = that wall in the server zone = the legacy value itself.
        assert_eq!(
            row_true_instant(&r, d, Some(d)),
            Some(utc_epoch(2024, 7, 4, 16, 0))
        );
    }

    #[test]
    fn unconverted_manual_row_interprets_wall_in_display_zone() {
        // Operator picked 2024-07-04 21:30 in their display zone (NY/EDT):
        // legacy = 21:30 naive-as-UTC, instant = 01:30 UTC July 5.
        let r = row(
            "manual.jpg",
            Some(utc_epoch(2024, 7, 4, 21, 30)),
            Some("manual"),
            None,
            None,
        );
        let d = ny();
        assert_eq!(
            row_display_wall(&r, d, Some(d)).map(|w| w.to_string()),
            Some("2024-07-04 21:30:00".to_string())
        );
        assert_eq!(
            row_true_instant(&r, d, Some(d)),
            Some(utc_epoch(2024, 7, 5, 1, 30))
        );
        assert_eq!(
            row_display_day(&r, d, Some(d)).map(|dt| dt.to_string()),
            Some("2024-07-04".to_string())
        );
    }

    #[test]
    fn unconverted_filename_wall_and_utc_patterns_diverge() {
        // Wall pattern (screenshot): legacy = wall as naive-as-UTC.
        let wall = row(
            "Screenshot_2024-07-04-21-30-00.png",
            Some(utc_epoch(2024, 7, 4, 21, 30)),
            Some("filename"),
            None,
            None,
        );
        // Unix-timestamp pattern: legacy is the true instant itself.
        let ts = row(
            "1720128600.jpg",
            Some(utc_epoch(2024, 7, 5, 1, 30)),
            Some("filename"),
            None,
            None,
        );
        let d = ny();
        assert_eq!(
            row_true_instant(&wall, d, Some(d)),
            Some(utc_epoch(2024, 7, 5, 1, 30)),
            "wall 21:30 EDT → 01:30 UTC"
        );
        assert_eq!(
            row_true_instant(&ts, d, Some(d)),
            Some(utc_epoch(2024, 7, 5, 1, 30)),
            "timestamp pattern is already the instant"
        );
        // Both land on the owner's July 4.
        for r in [&wall, &ts] {
            assert_eq!(
                row_display_day(r, d, Some(d)).map(|dt| dt.to_string()),
                Some("2024-07-04".to_string())
            );
        }
    }

    #[test]
    fn display_day_is_dst_correct_across_the_year() {
        // Same UTC instant, winter vs summer: the owner's day differs by
        // the DST shift. 04:30 UTC = 23:30 previous day EST, 00:30 same
        // day EDT.
        let winter = row(
            "w.jpg",
            Some(utc_epoch(2024, 1, 15, 4, 30)),
            Some("fs_time"),
            Some(utc_epoch(2024, 1, 15, 4, 30)),
            None,
        );
        let summer = row(
            "s.jpg",
            Some(utc_epoch(2024, 7, 15, 4, 30)),
            Some("fs_time"),
            Some(utc_epoch(2024, 7, 15, 4, 30)),
            None,
        );
        let d = ny();
        assert_eq!(
            row_display_day(&winter, d, Some(d)).map(|dt| dt.to_string()),
            Some("2024-01-14".to_string())
        );
        assert_eq!(
            row_display_day(&summer, d, Some(d)).map(|dt| dt.to_string()),
            Some("2024-07-15".to_string())
        );
    }

    #[test]
    fn display_day_respects_a_non_new_york_display_zone() {
        // Owner in Tokyo: 2024-07-05 01:30 UTC = 10:30 JST July 5 (not
        // the July 4 a NY owner sees).
        let (_, fs, _, instant) = ac3_fixtures();
        let tokyo = Tz::Asia__Tokyo;
        assert_eq!(
            row_display_day(&fs, tokyo, Some(ny())).map(|dt| dt.to_string()),
            Some("2024-07-05".to_string())
        );
        assert_eq!(row_true_instant(&fs, tokyo, Some(ny())), Some(instant));
    }

    #[test]
    fn wall_clock_is_the_camera_wall_for_a_travel_zone_photo() {
        // 14:00 in Tokyo (+09:00) = 05:00Z. The owner is in New York, but
        // the wall clock is the camera's: 14:00, not 01:00.
        let r = row(
            "otd.jpg",
            Some(utc_epoch(2018, 9, 29, 14, 0)),
            Some("exif"),
            Some(utc_epoch(2018, 9, 29, 5, 0)),
            Some(540),
        );
        assert_eq!(
            row_wall_clock(&r, ny(), Some(ny())),
            Some("2018-09-29T14:00:00".to_string())
        );
    }

    #[test]
    fn wall_clock_without_offset_renders_the_instant_in_the_display_zone() {
        // Container date (utc_direct): 12:30Z is 08:30 in New York (EDT).
        let r = row(
            "summit.mp4",
            None,
            Some("exiftool"),
            Some(utc_epoch(2022, 8, 20, 12, 30)),
            None,
        );
        assert_eq!(
            row_wall_clock(&r, ny(), Some(ny())),
            Some("2022-08-20T08:30:00".to_string())
        );
    }

    #[test]
    fn wall_clock_serves_unconverted_rows_by_their_legacy_convention() {
        // The drain's permanent floor never gets date_utc; an `exif` legacy
        // value is the wall stored as UTC and must come back unshifted.
        let r = row(
            "edited.jpg",
            Some(utc_epoch(2021, 5, 12, 10, 30)),
            Some("exif"),
            None,
            None,
        );
        assert_eq!(
            row_wall_clock(&r, ny(), Some(ny())),
            Some("2021-05-12T10:30:00".to_string())
        );
    }

    #[test]
    fn file_wall_clock_prefers_the_row() {
        let r = row(
            "Screenshots/Screenshot_20220315-101500.png",
            Some(utc_epoch(2022, 3, 15, 10, 15)),
            Some("filename"),
            Some(utc_epoch(2022, 3, 15, 14, 15)),
            Some(-240),
        );
        assert_eq!(
            file_wall_clock(Some(&r), &r.file_path, Some(0), ny(), Some(ny())),
            Some("2022-03-15T10:15:00".to_string())
        );
    }

    #[test]
    fn file_wall_clock_without_a_row_uses_the_filename_wall() {
        assert_eq!(
            file_wall_clock(
                None,
                "Screenshots/Screenshot_20220315-101500.png",
                Some(0),
                ny(),
                Some(ny())
            ),
            Some("2022-03-15T10:15:00".to_string())
        );
    }

    #[test]
    fn file_wall_clock_without_a_row_or_filename_date_uses_fs_time_in_display_zone() {
        // 2015-03-01 17:00Z = 12:00 in New York (EST).
        assert_eq!(
            file_wall_clock(
                None,
                "Undated/scan_01.jpg",
                Some(utc_epoch(2015, 3, 1, 17, 0)),
                ny(),
                Some(ny())
            ),
            Some("2015-03-01T12:00:00".to_string())
        );
        assert_eq!(
            file_wall_clock(None, "Undated/scan_01.jpg", None, ny(), Some(ny())),
            None
        );
    }
}