// SPDX-License-Identifier: GPL-3.0-only

use cosmic::Element;

use cosmic::iced::Length;

use cosmic::widget::{self, button, column, scrollable, text_input};

use crate::core::app::AppModel;

use crate::ui::languages::friendly_name;

use crate::ui::messages::{LanguageMessage, Message};

/// The language search sheet, in either of its two modes.

///

/// Both lists are the daemon's, never this app's. Which tags a model answers to

/// — whether it wants `en` or `en-US` — is a rule only the daemon's resolver

/// knows, and the global setting's vocabulary is the union of what the installed

/// models can speak, so it grows and shrinks as backends come and go. The

/// hard-coded table that used to fill the global half offered tags no model

/// served and, more quietly, never learned about the ones a freshly installed

/// backend added. `auto` is pinned rather than taken from either list, because

/// it is a control and not a language, and a search query must not be able to

/// filter it away.

pub fn sheet(app: &AppModel) -> Element<'_, Message> {

    let spacing = cosmic::theme::spacing();

    let q = app.language.language_picker_query.to_lowercase();

    // Build the candidate (tag, label) list for the active mode. Special

    // entries stay pinned at the top; the language entries are sorted

    // alphabetically by display name.

    let mut pinned: Vec<(Option<String>, String)> = Vec::new();

    let mut langs: Vec<(Option<String>, String)> = Vec::new();

    if let Some((ref src, ref mdl)) = app.language.language_picker_target {

        // Per-model sheet.

        pinned.push((None, "Follow global".to_string())); // clear → DELETE

        pinned.push((Some("auto".to_string()), friendly_name("auto"))); // "Auto-detect"

        // The tags this model can be pinned to — but only when the held list

        // belongs to this exact (source, model) pair (stale-list guard). An

        // empty list is a real answer for a monolingual model, and leaves the

        // sheet with nothing but the two pinned controls.

        if app.language.model_language_for.as_ref() == Some(&(src.clone(), mdl.clone())) {

            for tag in &app.language.model_languages {

                if tag.eq_ignore_ascii_case("auto") {

                    continue; // already pinned as "Auto-detect"

                }

                langs.push((Some(tag.clone()), friendly_name(tag)));

            }

        }

    } else {

        // Global sheet — "Auto-detect" only; the unset state is reached by not

        // choosing anything, so there is no explicit "No preference" entry.

        pinned.push((Some("auto".to_string()), friendly_name("auto"))); // "Auto-detect"

        for tag in &app.language.primary_languages {

            if tag.eq_ignore_ascii_case("auto") {

                continue; // the daemon always includes it; it is pinned above

            }

            langs.push((Some(tag.clone()), friendly_name(tag)));

        }

    }

    langs.sort_by(|a, b| a.1.cmp(&b.1));

    // The pinned controls always show; only the language list is narrowed by the

    // search query, so the user can never filter away "Auto-detect" / "Follow

    // global".

    let rows: Vec<(Option<String>, String)> = pinned

        .into_iter()

        .chain(langs.into_iter().filter(|(tag, label)| {

            if q.is_empty() {

                return true;

            }

            let hay = format!("{label} {}", tag.as_deref().unwrap_or("")).to_lowercase();

            hay.contains(&q)

        }))

        .collect();

    // Search field pinned at the top.

    let search = text_input("Search languages…", &app.language.language_picker_query)

        .on_input(|s| Message::Language(LanguageMessage::LanguagePickerQueryChanged(s)))

        .width(Length::Fill);

    let mut list = column::with_capacity(rows.len()).spacing(spacing.space_xxs);

    for (tag, label) in rows {

        let msg = if let Some((ref src, ref mdl)) = app.language.language_picker_target {

            Message::Language(LanguageMessage::ModelLanguageSelected {

                source: src.clone(),

                model: mdl.clone(),

                choice: tag,

            })

        } else {

            Message::Language(LanguageMessage::PrimaryLanguageSelected(tag))

        };

        list = list.push(button::text(label).width(Length::Fill).on_press(msg));

    }

    widget::column::with_capacity(2)

        .spacing(spacing.space_s)

        .push(search)

        .push(scrollable(list).height(Length::Fill))

        .width(Length::Fill)

        .into()

}