//! TRACES: FR-CULL-10 | FR-CULL-11 | FR-CULL-12 | NFR-SEC-5
//! The Identity screen's model: who the library knows, and how the user fixes it.
//!
//! A third top-level screen beside the library and develop, because it is a
//! *place you go to work*, not a panel you glance at: naming a cluster, pulling
//! a stranger out of it, and merging two halves of the same person are tasks
//! with their own rhythm, and they need the whole window.
//!
//! # The screen exists because the clustering is wrong
//!
//! That is not pessimism, it is FR-CULL-10: clustering will over-merge on
//! siblings, on parents and children, and on the same person a decade apart. A
//! tool that could only merge would make its own errors permanent, so
//! **splitting is as prominent as merging here**, and every suggestion is
//! visibly a suggestion until the user says otherwise.
//!
//! # What this module is, and is not
//!
//! It builds a view model from the catalog and applies the user's decisions
//! back to it. It holds no Slint types, so the whole of it is testable against
//! an in-memory catalog with no window open — which matters because the
//! operations it performs are the ones that touch user data.

use dr_catalog::faces::{self, FaceId, PersonId};
use dr_catalog::Catalog;
use dr_thumbs::ThumbStore;
use dr_types::ImageId;

use crate::faces::{crop_face, FaceCrop, FACE_TIER};

/// Edge of a face crop in the grid, in pixels.
///
/// Generous for a thumbnail because the judgement being asked for — *is this
/// the same person* — is one the user cannot make from a postage stamp.
pub const FACE_CROP_EDGE: u32 = 128;

/// A row in the people rail.
#[derive(Debug, Clone, PartialEq)]
pub struct PersonRow {
    pub id: PersonId,
    /// Empty for a cluster the system found and the user has not named.
    pub name: String,
    pub confirmed_faces: u64,
    pub suggested_faces: u64,
    /// The face to show as this person's portrait, if any is loaded.
    pub cover: Option<FaceId>,
}

impl PersonRow {
    /// What to draw when the person has no name yet.
    ///
    /// Deliberately not a guessed name. FR-CULL-10 has the *user* name a group,
    /// and a system-chosen name would be an inference wearing a fact's clothes
    /// — the exact conflation the confirmed/suggested split exists to prevent.
    pub fn display_name(&self) -> String {
        if self.name.is_empty() {
            format!("Unnamed ({} faces)", self.confirmed_faces + self.suggested_faces)
        } else {
            self.name.clone()
        }
    }

    /// Whether this group is still entirely the system's opinion.
    pub fn is_unconfirmed(&self) -> bool {
        self.confirmed_faces == 0
    }
}

/// One face in the grid.
#[derive(Debug, Clone, PartialEq)]
pub struct FaceCell {
    pub face: FaceId,
    pub image: ImageId,
    /// `None` while the crop is still being cut.
    pub crop: Option<FaceCrop>,
    /// The user asserted this, as against the system guessing it.
    pub confirmed: bool,
    /// Calibrated P(this face is this person).
    pub probability: f32,
    /// Whether that probability means anything — false when the library's
    /// calibration has not been fitted (FR-CULL-9).
    pub probability_known: bool,
    /// Source pixels across the aligned crop. Small faces embed worse, and the
    /// user deserves to know which of a bad suggestion's causes is in play.
    pub crop_px: f32,
}

impl FaceCell {
    /// Confidence as text, or why there is none.
    ///
    /// The FR-CULL-9 rule made concrete: where the calibration is not fitted,
    /// this says so rather than printing an untuned number that looks measured.
    pub fn confidence_label(&self) -> String {
        if self.confirmed {
            "Confirmed".into()
        } else if !self.probability_known {
            "Confidence unavailable".into()
        } else {
            format!("{:.0}% likely", self.probability * 100.0)
        }
    }
}

/// Everything the Identity screen draws.
#[derive(Debug, Clone, Default, PartialEq)]
pub struct IdentityView {
    pub people: Vec<PersonRow>,
    pub selected: Option<PersonId>,
    pub faces: Vec<FaceCell>,
    /// Faces belonging to nobody — the pool the user can pull a new person out
    /// of, and the honest answer to "why is this photo not under anyone".
    pub unassigned: usize,
    /// Whether the library's similarity calibration has been fitted.
    pub calibrated: bool,
}

/// Read the people rail.
pub fn load_people(catalog: &Catalog, model_id: &str) -> Result<IdentityView, dr_catalog::CatalogError> {
    let conn = catalog.connection();
    let people = faces::people(conn)?
        .into_iter()
        .map(|p| PersonRow {
            id: p.id,
            name: p.name,
            confirmed_faces: p.confirmed_faces,
            suggested_faces: p.suggested_faces,
            cover: None,
        })
        .collect();

    Ok(IdentityView {
        people,
        selected: None,
        faces: Vec::new(),
        unassigned: faces::unassigned(conn, model_id)?.len(),
        calibrated: faces::calibration(conn, model_id)?.is_some_and(|(c, _)| c.valid),
    })
}

/// Read one person's faces, cutting a crop for each.
///
/// Suggestions are included and marked, never hidden: the whole purpose of this
/// screen is ruling on them, and a screen that showed only confirmed faces
/// would give the user nothing to do.
///
/// Crops come from the proxy the grid already built. An image whose proxy has
/// been evicted yields a cell with no crop rather than being dropped — the face
/// is still real, still counted, and still confirmable from its filename.
pub fn load_faces(
    catalog: &Catalog,
    store: &ThumbStore,
    person: PersonId,
    calibrated: bool,
) -> Result<Vec<FaceCell>, dr_catalog::CatalogError> {
    let conn = catalog.connection();
    let rows = faces::for_person(conn, person, true)?;

    // One decode per *image*, not per face: a group photograph holding six
    // faces of one family is one JPEG, and decoding it six times is the kind of
    // waste that only shows up on a slow machine.
    let mut decoded: std::collections::HashMap<ImageId, Option<(u32, u32, Vec<u8>)>> =
        std::collections::HashMap::new();

    let mut out = Vec::with_capacity(rows.len());
    for f in rows {
        let entry = decoded
            .entry(f.image_id)
            .or_insert_with(|| decode_proxy(catalog, store, f.image_id));

        let crop = entry
            .as_ref()
            .and_then(|(w, h, rgba)| crop_face(rgba, *w, *h, &f, FACE_CROP_EDGE));

        out.push(FaceCell {
            face: f.id,
            image: f.image_id,
            crop,
            confirmed: f.confirmed,
            probability: f.probability,
            probability_known: calibrated,
            crop_px: f.crop_px,
        });
    }

    Ok(out)
}

fn decode_proxy(
    catalog: &Catalog,
    store: &ThumbStore,
    image: ImageId,
) -> Option<(u32, u32, Vec<u8>)> {
    let file_id: i64 = catalog
        .connection()
        .query_row(
            "SELECT file_id FROM remote WHERE image_id = ?1",
            [image.0 as i64],
            |r| r.get(0),
        )
        .ok()?;
    let thumb = store.get(file_id as u64, FACE_TIER).ok()??;
    dr_thumbs::codec::decode_rgba(&thumb.bytes).ok()
}

// ── the user's decisions ──────────────────────────────────────────────────

/// Name a group, or rename a person.
///
/// The identity is untouched: FR-CULL-12 makes a *name* the user data that
/// travels to the sidecar, while the person's UUID is what a cross-device merge
/// keys on, and renaming must not create a second person on the other device.
pub fn rename(
    catalog: &Catalog,
    person: PersonId,
    name: &str,
) -> Result<(), dr_catalog::CatalogError> {
    faces::rename_person(catalog.connection(), person, name.trim())
}

/// Confirm every suggestion in a group at once.
///
/// The operation the screen exists to make cheap. A cluster that is simply
/// right — the common case for a well-photographed person — should cost one
/// click, not forty.
pub fn confirm_all(
    catalog: &Catalog,
    person: PersonId,
) -> Result<usize, dr_catalog::CatalogError> {
    let conn = catalog.connection();
    let mut n = 0;
    for f in faces::for_person(conn, person, true)? {
        if !f.confirmed {
            faces::confirm(conn, f.id, person)?;
            n += 1;
        }
    }
    Ok(n)
}

/// The user says this face is this person.
pub fn confirm(
    catalog: &Catalog,
    face: FaceId,
    person: PersonId,
) -> Result<(), dr_catalog::CatalogError> {
    faces::confirm(catalog.connection(), face, person)
}

/// The user says this face is not this person.
///
/// Remembered, so the next clustering pass does not put it straight back —
/// which is the difference between a correction and a recurring argument.
pub fn reject(
    catalog: &Catalog,
    face: FaceId,
    person: PersonId,
) -> Result<(), dr_catalog::CatalogError> {
    faces::reject(catalog.connection(), face, person)
}

/// Fold one person into another.
pub fn merge(
    catalog: &Catalog,
    target: PersonId,
    source: PersonId,
) -> Result<u64, dr_catalog::CatalogError> {
    faces::merge_people(catalog.connection(), target, source)
}

/// What a split would produce, without performing it.
///
/// Offered as a preview because a split is the destructive-feeling half of
/// FR-CULL-10 and the user should see the groups before agreeing to them. It
/// re-agglomerates this person's faces at a stricter threshold; a person who is
/// genuinely one person comes back as one group and the UI can say so instead
/// of splitting nothing.
pub fn preview_split(
    catalog: &Catalog,
    store: &ThumbStore,
    person: PersonId,
    model_id: &str,
    strictness: f32,
) -> Result<Vec<Vec<FaceCell>>, dr_catalog::CatalogError> {
    let conn = catalog.connection();
    let cal = faces::calibration(conn, model_id)?
        .map(|(c, _)| c)
        .unwrap_or_default();
    let calibrated = cal.valid;

    let cells = load_faces(catalog, store, person, calibrated)?;
    if cells.len() < 2 {
        return Ok(vec![cells]);
    }

    let model = dr_face::ModelId::new(model_id.to_string());
    let stored: std::collections::HashMap<_, _> = faces::embeddings(conn, model_id)?
        .into_iter()
        .map(|(id, image, blob, crop_px)| (id, (image, blob, crop_px)))
        .collect();

    let mut candidates = Vec::with_capacity(cells.len());
    let mut order = Vec::with_capacity(cells.len());
    for c in &cells {
        let Some((image, blob, crop_px)) = stored.get(&c.face) else {
            continue;
        };
        let Some(emb) = dr_face::Embedding::from_f16_bytes(model.clone(), blob) else {
            continue;
        };
        candidates.push(dr_face::Candidate {
            face: c.face.0,
            image: image.0,
            embedding: emb.v.to_vec(),
            crop_px: *crop_px,
            confirmed_person: None,
        });
        order.push(c.clone());
    }

    let groups = dr_face::split(&candidates, &cal, strictness);
    Ok(groups
        .into_iter()
        .map(|g| g.members.into_iter().map(|m| order[m].clone()).collect())
        .collect())
}

/// Pull a set of faces out of a person and onto a new one.
///
/// The commit half of [`preview_split`], and also what "these three are
/// actually someone else" does. The faces are **confirmed** onto the new
/// person, because the user has just asserted they belong together — leaving
/// them as suggestions would invite the next clustering pass to undo the
/// correction.
pub fn split_off(
    catalog: &Catalog,
    from: PersonId,
    members: &[FaceId],
    name: &str,
) -> Result<PersonId, dr_catalog::CatalogError> {
    let conn = catalog.connection();
    let new_person = faces::create_person(conn, name.trim())?;
    for &face in members {
        // Rejecting first is what stops the split being undone: without it the
        // next pass sees a face that looks like `from` and suggests it straight
        // back, and the user's correction becomes an argument they keep having.
        faces::reject(conn, face, from)?;
        faces::confirm(conn, face, new_person)?;
    }
    Ok(new_person)
}

/// Detach a face from everyone, asserting nothing.
///
/// Distinct from [`reject`]: this is "I do not know", and the face returns to
/// the pool for the next clustering pass to place. Needed for the case where
/// the user can see a crop is a lamp, not a person — rejecting it from *this*
/// person would leave it free to be suggested for the next one.
pub fn unassign(catalog: &Catalog, face: FaceId) -> Result<(), dr_catalog::CatalogError> {
    faces::unassign(catalog.connection(), face)
}

/// Delete every face, person and embedding in the library (NFR-SEC-5).
///
/// Surfaced from this screen because this is where the user's face data
/// visibly lives, and a control to remove it that is hidden in a settings page
/// three levels down is a control that does not really exist.
pub fn delete_all(catalog: &Catalog) -> Result<u64, dr_catalog::CatalogError> {
    faces::delete_all_face_data(catalog.connection())
}

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

    fn catalog() -> Catalog {
        let dir = std::env::temp_dir().join(format!(
            "dr-identity-{}-{:?}",
            std::process::id(),
            std::thread::current().id()
        ));
        std::fs::create_dir_all(&dir).unwrap();
        let path = dir.join("catalog.db");
        let _ = std::fs::remove_file(&path);
        Catalog::open(&path).unwrap()
    }

    fn image(c: &Catalog, n: i64) -> ImageId {
        let conn = c.connection();
        conn.execute(
            "INSERT OR IGNORE INTO roots(id, kind, label) VALUES (1, 'local', 'lib')",
            [],
        )
        .unwrap();
        conn.execute(
            "INSERT INTO images(id, root_id, source_ref, added_at) VALUES (?1, 1, ?2, 0)",
            rusqlite::params![n, format!("IMG_{n}.CR3")],
        )
        .unwrap();
        ImageId(n as u64)
    }

    fn face(seed: u8) -> DetectedFace {
        DetectedFace {
            x: 0.1,
            y: 0.1,
            w: 0.2,
            h: 0.3,
            landmarks: [(0.1, 0.1); 5],
            confidence: 0.9,
            embedding: vec![seed; 1024],
            crop_px: 180.0,
            model_id: "w600k_mbf".into(),
        }
    }

    #[test]
    fn an_unnamed_group_says_how_many_faces_it_holds_rather_than_guessing_a_name() {
        let row = PersonRow {
            id: PersonId(1),
            name: String::new(),
            confirmed_faces: 0,
            suggested_faces: 12,
            cover: None,
        };
        assert_eq!(row.display_name(), "Unnamed (12 faces)");
        assert!(row.is_unconfirmed());
    }

    #[test]
    fn a_named_person_shows_their_name() {
        let row = PersonRow {
            id: PersonId(1),
            name: "Anna".into(),
            confirmed_faces: 4,
            suggested_faces: 2,
            cover: None,
        };
        assert_eq!(row.display_name(), "Anna");
        assert!(!row.is_unconfirmed());
    }

    /// FR-CULL-9's rule at the point it becomes visible: an unfitted
    /// calibration must not print a number that looks measured.
    #[test]
    fn an_uncalibrated_library_says_so_instead_of_showing_a_percentage() {
        let cell = FaceCell {
            face: FaceId(1),
            image: ImageId(1),
            crop: None,
            confirmed: false,
            probability: 0.87,
            probability_known: false,
            crop_px: 120.0,
        };
        assert_eq!(cell.confidence_label(), "Confidence unavailable");

        let calibrated = FaceCell {
            probability_known: true,
            ..cell.clone()
        };
        assert_eq!(calibrated.confidence_label(), "87% likely");

        let confirmed = FaceCell {
            confirmed: true,
            probability_known: false,
            ..cell
        };
        assert_eq!(confirmed.confidence_label(), "Confirmed");
    }

    #[test]
    fn the_people_rail_reports_the_unassigned_pool() {
        let c = catalog();
        let i1 = image(&c, 1);
        let i2 = image(&c, 2);
        let a = faces::record_detections(c.connection(), i1, "w600k_mbf", 1024, &[face(1)]).unwrap();
        faces::record_detections(c.connection(), i2, "w600k_mbf", 1024, &[face(2)]).unwrap();

        let anna = faces::create_person(c.connection(), "Anna").unwrap();
        faces::confirm(c.connection(), a[0], anna).unwrap();

        let view = load_people(&c, "w600k_mbf").unwrap();
        assert_eq!(view.people.len(), 1);
        assert_eq!(view.people[0].name, "Anna");
        assert_eq!(view.unassigned, 1);
        assert!(!view.calibrated, "a fresh library has no fitted calibration");
    }

    #[test]
    fn confirm_all_promotes_every_suggestion_and_nothing_else() {
        let c = catalog();
        let i1 = image(&c, 1);
        let i2 = image(&c, 2);
        let i3 = image(&c, 3);
        let a = faces::record_detections(c.connection(), i1, "w600k_mbf", 1024, &[face(1)]).unwrap();
        let b = faces::record_detections(c.connection(), i2, "w600k_mbf", 1024, &[face(2)]).unwrap();
        let d = faces::record_detections(c.connection(), i3, "w600k_mbf", 1024, &[face(3)]).unwrap();

        let anna = faces::create_person(c.connection(), "Anna").unwrap();
        faces::confirm(c.connection(), a[0], anna).unwrap();
        faces::suggest(c.connection(), b[0], anna, 0.8).unwrap();
        faces::suggest(c.connection(), d[0], anna, 0.7).unwrap();

        assert_eq!(confirm_all(&c, anna).unwrap(), 2);
        assert_eq!(confirm_all(&c, anna).unwrap(), 0, "should be idempotent");
        assert_eq!(faces::for_person(c.connection(), anna, false).unwrap().len(), 3);
    }

    /// The correction must stick. Splitting a face off and then re-running
    /// clustering must not put it back where the user took it from.
    #[test]
    fn a_split_face_is_not_suggested_back_to_the_person_it_left() {
        let c = catalog();
        let i1 = image(&c, 1);
        let i2 = image(&c, 2);
        let a = faces::record_detections(c.connection(), i1, "w600k_mbf", 1024, &[face(1)]).unwrap();
        let b = faces::record_detections(c.connection(), i2, "w600k_mbf", 1024, &[face(2)]).unwrap();

        let anna = faces::create_person(c.connection(), "Anna").unwrap();
        faces::confirm(c.connection(), a[0], anna).unwrap();
        faces::suggest(c.connection(), b[0], anna, 0.95).unwrap();

        let bob = split_off(&c, anna, &[b[0]], "Bob").unwrap();
        assert_eq!(faces::for_person(c.connection(), bob, false).unwrap().len(), 1);
        assert_eq!(faces::for_person(c.connection(), anna, true).unwrap().len(), 1);

        // The next clustering pass tries again and is refused.
        assert!(
            !faces::suggest(c.connection(), b[0], anna, 0.99).unwrap(),
            "the split was undone by the next inference pass"
        );
    }

    #[test]
    fn renaming_trims_and_keeps_the_person() {
        let c = catalog();
        let anna = faces::create_person(c.connection(), "").unwrap();
        rename(&c, anna, "  Anna Smith  ").unwrap();
        let people = faces::people(c.connection()).unwrap();
        assert_eq!(people[0].name, "Anna Smith");
        assert_eq!(people[0].id, anna);
    }

    #[test]
    fn merging_folds_one_person_into_the_other() {
        let c = catalog();
        let i1 = image(&c, 1);
        let i2 = image(&c, 2);
        let a = faces::record_detections(c.connection(), i1, "w600k_mbf", 1024, &[face(1)]).unwrap();
        let b = faces::record_detections(c.connection(), i2, "w600k_mbf", 1024, &[face(2)]).unwrap();
        let anna = faces::create_person(c.connection(), "Anna").unwrap();
        let annie = faces::create_person(c.connection(), "Annie").unwrap();
        faces::confirm(c.connection(), a[0], anna).unwrap();
        faces::confirm(c.connection(), b[0], annie).unwrap();

        assert_eq!(merge(&c, anna, annie).unwrap(), 1);
        assert_eq!(load_people(&c, "w600k_mbf").unwrap().people.len(), 1);
    }

    #[test]
    fn deleting_everything_empties_the_screen() {
        let c = catalog();
        let i1 = image(&c, 1);
        let a = faces::record_detections(c.connection(), i1, "w600k_mbf", 1024, &[face(1)]).unwrap();
        let anna = faces::create_person(c.connection(), "Anna").unwrap();
        faces::confirm(c.connection(), a[0], anna).unwrap();

        assert_eq!(delete_all(&c).unwrap(), 1);
        let view = load_people(&c, "w600k_mbf").unwrap();
        assert!(view.people.is_empty());
        assert_eq!(view.unassigned, 0);
    }
}