//! Library view state: what the grid shows and what is selected.

use lightcraft_catalog::{AlbumId, Catalog, Filter, PhotoId};
use serde::{Deserialize, Serialize};

/// The "My Photos" source in the left panel.
#[derive(Clone, Copy, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
#[serde(tag = "kind", content = "id", rename_all = "camelCase")]
pub enum LibrarySource {
    #[default]
    All,
    /// Imported in the last import session (we treat "recent" as the latest import date).
    RecentlyAdded,
    Album(AlbumId),
    RecentlyDeleted,
    /// Photos with picks.
    Picks,
    /// A folder on disk ([`crate::Session::browse`]): its files, added to the library or not.
    Folder,
    /// Photos whose original file can't be found (`library.missing`).
    Missing,
}

/// The folder a [`LibrarySource::Folder`] view shows.
#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
#[serde(default)]
pub struct Browse {
    pub path: String,
    pub subfolders: bool,
}

/// How far back Recently Added reaches from the latest import.
pub const RECENT_DAYS: i64 = 30;

impl LibrarySource {
    pub fn to_filter(&self, f: &Filter, cat: &Catalog) -> Filter {
        let mut f = f.clone();
        match self {
            LibrarySource::All => {}
            // everything imported in the 30 days up to the latest import (by import, newest first)
            LibrarySource::RecentlyAdded => {
                let latest = cat.photos().filter(|p| p.in_library()).map(|p| p.imported.clone()).max().unwrap_or_default();
                let from = lightcraft_catalog::stacks::iso_seconds(&latest)
                    .map(|s| lightcraft_catalog::dates::civil(s - RECENT_DAYS * 86_400))
                    .unwrap_or_else(|| latest.get(..10).unwrap_or("").to_string());
                f.imported_from = Some(from);
            }
            LibrarySource::Album(a) => f.album = Some(*a),
            LibrarySource::RecentlyDeleted => f.deleted = true,
            LibrarySource::Picks => f.flag = Some(lightcraft_catalog::Flag::Pick),
            // the folder itself is filled in by the session (it holds the path)
            LibrarySource::Folder | LibrarySource::Missing => {}
        }
        f
    }

    pub fn label(&self, cat: &Catalog) -> String {
        match self {
            LibrarySource::All => "All Photos".into(),
            LibrarySource::RecentlyAdded => "Recently Added".into(),
            LibrarySource::Album(a) => cat.album(*a).map(|a| a.name.clone()).unwrap_or_else(|| "Album".into()),
            LibrarySource::RecentlyDeleted => "Recently Deleted".into(),
            LibrarySource::Picks => "Picks".into(),
            LibrarySource::Folder => "Folder".into(),
            LibrarySource::Missing => "Missing Photos".into(),
        }
    }
}

/// Selected photos (ordered) and the active (most-selected) one.
#[derive(Clone, Debug, Default, PartialEq, Eq, Serialize, Deserialize)]
pub struct Selection {
    pub ids: Vec<PhotoId>,
    pub active: Option<PhotoId>,
}

impl Selection {
    pub fn single(id: PhotoId) -> Selection {
        Selection { ids: vec![id], active: Some(id) }
    }
    pub fn contains(&self, id: PhotoId) -> bool {
        self.ids.contains(&id)
    }
    pub fn toggle(&mut self, id: PhotoId) {
        if let Some(i) = self.ids.iter().position(|x| *x == id) {
            self.ids.remove(i);
            if self.active == Some(id) {
                self.active = self.ids.last().copied();
            }
        } else {
            self.ids.push(id);
            self.active = Some(id);
        }
    }
    /// Shift-click: select the range between the active photo and `id` in `order`.
    pub fn extend_to(&mut self, id: PhotoId, order: &[PhotoId]) {
        let anchor = self.active.unwrap_or(id);
        let (Some(a), Some(b)) = (order.iter().position(|x| *x == anchor), order.iter().position(|x| *x == id)) else {
            *self = Selection::single(id);
            return;
        };
        let (lo, hi) = (a.min(b), a.max(b));
        for x in &order[lo..=hi] {
            if !self.ids.contains(x) {
                self.ids.push(*x);
            }
        }
        self.active = Some(id);
    }
}

/// One active filter, shown as a removable chip above the grid.
#[derive(Clone, Debug, PartialEq)]
pub struct FilterChip {
    pub label: String,
    /// `library.filter` patch that clears just this filter.
    pub clear: serde_json::Value,
}

/// The chips for every constraint in the filter bar / search / sidebar (not the source itself).
pub fn filter_chips(f: &Filter, cat: &Catalog) -> Vec<FilterChip> {
    use lightcraft_catalog::{MediaKind, RatingOp};
    use serde_json::{Value::Null, json};
    let mut v = Vec::new();
    let mut add = |label: String, clear: serde_json::Value| v.push(FilterChip { label, clear });
    if !f.text.trim().is_empty() {
        add(format!("Search: “{}”", f.text.trim()), json!({"text": ""}));
    }
    if f.rating > 0 {
        let op = match f.rating_op {
            RatingOp::AtLeast => "≥",
            RatingOp::Exactly => "=",
            RatingOp::AtMost => "≤",
        };
        add(format!("Rating {op} {}★", f.rating), json!({"rating": 0}));
    }
    if let Some(fl) = f.flag {
        add(format!("Flag: {}", format!("{fl:?}").to_lowercase()), json!({"flag": Null}));
    }
    let mut labels = f.labels.clone();
    labels.extend(f.label.filter(|l| !labels.contains(l)));
    if !labels.is_empty() {
        let names: Vec<String> = labels.iter().map(|l| cat.label_name(*l)).collect();
        add(format!("Label: {}", names.join(" or ")), json!({"label": Null, "labels": []}));
    }
    if let Some(k) = f.kind {
        let n = match k {
            MediaKind::Image => "Photos",
            MediaKind::Raw => "Raw",
            MediaKind::Video => "Videos",
        };
        add(format!("Type: {n}"), json!({"kind": Null}));
    }
    if let Some(m) = &f.merged {
        let n = match m.as_str() {
            "hdr" => "HDR",
            "panorama" => "Panoramas",
            "hdrPanorama" => "HDR panoramas",
            _ => "Merged",
        };
        add(format!("Type: {n}"), json!({"merged": Null}));
    }
    if let Some(e) = f.edited {
        add(if e { "Edited".into() } else { "Unedited".into() }, json!({"edited": Null}));
    }
    for (name, key, val) in
        [("Camera", "camera", &f.camera), ("Lens", "lens", &f.lens), ("Keyword", "keyword", &f.keyword), ("Person", "person", &f.person)]
    {
        if let Some(x) = val {
            add(format!("{name}: {x}"), json!({key: Null}));
        }
    }
    if let Some(d) = &f.date {
        add(format!("Date: {}", date_label(d)), json!({"date": Null}));
    }
    if let Some(d) = &f.imported {
        add(format!("Imported: {}", date_label(d)), json!({"imported": Null}));
    }
    match (&f.date_from, &f.date_to) {
        (Some(a), Some(b)) => add(format!("Captured {a} – {b}"), json!({"dateFrom": Null, "dateTo": Null})),
        (Some(a), None) => add(format!("Captured from {a}"), json!({"dateFrom": Null})),
        (None, Some(b)) => add(format!("Captured until {b}"), json!({"dateTo": Null})),
        _ => {}
    }
    if let Some(rs) = f.rule_set.as_ref().filter(|r| !r.rules.is_empty()) {
        add(format!("Rules: {}", rs.describe()), json!({"ruleSet": Null}));
    }
    if !f.only.is_empty() {
        add(format!("Only {} photos", f.only.len()), json!({"only": []}));
    }
    v
}

/// `2026-01-16` → "January 16, 2026"; `2026-01` → "January 2026"; anything else as is.
fn date_label(d: &str) -> String {
    const MONTHS: [&str; 12] =
        ["January", "February", "March", "April", "May", "June", "July", "August", "September", "October", "November", "December"];
    let parts: Vec<&str> = d.split('-').collect();
    let month = parts.get(1).and_then(|m| m.parse::<usize>().ok()).filter(|m| (1..=12).contains(m)).map(|m| MONTHS[m - 1]);
    match (parts.as_slice(), month) {
        ([y, _, day], Some(m)) => format!("{m} {}, {y}", day.trim_start_matches('0')),
        ([y, _], Some(m)) => format!("{m} {y}"),
        _ => d.to_string(),
    }
}