a/src/stdlib/tui/prompts.rs

//! The interactive prompts (`tui.confirm`, `tui.prompt*`), backed by the
//! `inquire` crate.
//!
//! inquire prompts block their thread (crossterm raw mode), so each one runs
//! under `spawn_blocking` like sqlite's I/O — the calling Lua coroutine
//! suspends while timers and sibling coroutines keep running. A process-wide
//! mutex serializes prompts so two coroutines under `task.join` can't fight
//! over the terminal.
//!
//! Each Lua binding validates its arguments into a `Send` config struct
//! *before* spawning, so malformed calls error deterministically even without
//! a terminal; the `run_*` workers then build and drive the inquire prompt on
//! the blocking pool.

use std::fmt;
use std::sync::Mutex;

use chrono::NaiveDate;
use inquire::autocompletion::{Autocomplete, Replacement};
use inquire::error::CustomUserError;
use inquire::list_option::ListOption;
use inquire::validator::Validation;
use inquire::{
    Confirm, CustomType, DateSelect, Editor, InquireError, MultiSelect, Password,
    PasswordDisplayMode, Select, Text,
};
use mlua::prelude::{LuaResult, LuaTable, LuaValue};
use mlua::Lua;

use super::ext_err;
use super::opts::{
    bounds_message, check_bounds, default_string, int_of, lua_value_brief, parse_date, text_arg,
    Opts, DATE_FMT,
};

/// Serializes terminal ownership across concurrent Lua coroutines. Locked
/// inside the blocking closure, so a waiting prompt parks a blocking-pool
/// thread, never the tokio event loop. Shared with `term`'s cursor-position
/// query and the fs module's permission prompt, which also read from the
/// terminal (re-exported as `stdlib::tui::PROMPT_LOCK`).
pub(crate) static PROMPT_LOCK: Mutex<()> = Mutex::new(());

/// `Send`-safe error carried out of the blocking prompt worker; the Lua-side
/// wrapper prepends the `tui.<fn>:` prefix.
enum PromptError {
    Interrupted,
    NotTty,
    Other(String),
}

impl fmt::Display for PromptError {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        match self {
            PromptError::Interrupted => f.write_str("interrupted"),
            PromptError::NotTty => f.write_str("not a terminal"),
            PromptError::Other(msg) => f.write_str(msg),
        }
    }
}

/// Fold an inquire outcome into the module's cancellation model:
/// Esc → `Ok(None)` (surfaces as `nil`), Ctrl-C / no-tty / everything else →
/// error.
fn map_inquire_result<T>(r: Result<T, InquireError>) -> Result<Option<T>, PromptError> {
    match r {
        Ok(v) => Ok(Some(v)),
        Err(InquireError::OperationCanceled) => Ok(None),
        Err(InquireError::OperationInterrupted) => Err(PromptError::Interrupted),
        Err(InquireError::NotTTY) => Err(PromptError::NotTty),
        Err(e) => Err(PromptError::Other(e.to_string())),
    }
}

/// Run a blocking prompt worker on the blocking pool, holding the prompt
/// lock, and translate its error with the `tui.<fn>:` prefix.
async fn run_prompt<T, F>(fname: &'static str, worker: F) -> LuaResult<Option<T>>
where
    T: Send + 'static,
    F: FnOnce() -> Result<Option<T>, PromptError> + Send + 'static,
{
    tokio::task::spawn_blocking(move || {
        let _guard = PROMPT_LOCK.lock().unwrap_or_else(|e| e.into_inner());
        worker()
    })
    .await
    .unwrap_or_else(|e| Err(PromptError::Other(format!("background task failed: {e}"))))
    .map_err(|e| ext_err!("{fname}: {e}"))
}

fn find_option_index(fname: &str, options: &[String], value: &str) -> LuaResult<usize> {
    options
        .iter()
        .position(|o| o == value)
        .ok_or_else(|| ext_err!("{fname}: default '{value}' is not one of the options"))
}

/// Ensure an editor file extension has its leading dot (`md` → `.md`).
fn normalize_extension(ext: &str) -> String {
    if ext.starts_with('.') {
        ext.to_string()
    } else {
        format!(".{ext}")
    }
}

/// Static-list autocompleter for `promptText`'s `suggestions` option:
/// case-insensitive substring filter, Tab completes the highlighted entry.
#[derive(Clone)]
struct StaticSuggester(Vec<String>);

impl Autocomplete for StaticSuggester {
    fn get_suggestions(&mut self, input: &str) -> Result<Vec<String>, CustomUserError> {
        let needle = input.to_lowercase();
        Ok(self
            .0
            .iter()
            .filter(|s| s.to_lowercase().contains(&needle))
            .cloned()
            .collect())
    }

    fn get_completion(
        &mut self,
        _input: &str,
        highlighted_suggestion: Option<String>,
    ) -> Result<Replacement, CustomUserError> {
        Ok(highlighted_suggestion)
    }
}

struct ConfirmCfg {
    text: String,
    default: Option<bool>,
    help: Option<String>,
    placeholder: Option<String>,
}

fn run_confirm(cfg: &ConfirmCfg) -> Result<Option<bool>, PromptError> {
    let mut p = Confirm::new(&cfg.text);
    if let Some(d) = cfg.default {
        p = p.with_default(d);
    }
    if let Some(h) = &cfg.help {
        p = p.with_help_message(h);
    }
    if let Some(ph) = &cfg.placeholder {
        p = p.with_placeholder(ph);
    }
    map_inquire_result(p.prompt())
}

struct TextCfg {
    text: String,
    initial: Option<String>,
    default: Option<String>,
    help: Option<String>,
    placeholder: Option<String>,
    min_len: Option<usize>,
    max_len: Option<usize>,
    suggestions: Option<Vec<String>>,
    page_size: Option<usize>,
}

fn run_text(cfg: &TextCfg) -> Result<Option<String>, PromptError> {
    let mut p = Text::new(&cfg.text);
    if let Some(v) = &cfg.initial {
        p = p.with_initial_value(v);
    }
    if let Some(v) = &cfg.default {
        p = p.with_default(v);
    }
    if let Some(h) = &cfg.help {
        p = p.with_help_message(h);
    }
    if let Some(ph) = &cfg.placeholder {
        p = p.with_placeholder(ph);
    }
    if cfg.min_len.is_some() || cfg.max_len.is_some() {
        let (min, max) = (cfg.min_len, cfg.max_len);
        let msg = bounds_message("length", &min, &max);
        p = p.with_validator(move |s: &str| {
            let len = s.chars().count();
            let ok = min.is_none_or(|m| len >= m) && max.is_none_or(|m| len <= m);
            if ok {
                Ok(Validation::Valid)
            } else {
                Ok(Validation::Invalid(msg.clone().into()))
            }
        });
    }
    if let Some(sugg) = &cfg.suggestions {
        p = p.with_autocomplete(StaticSuggester(sugg.clone()));
    }
    if let Some(n) = cfg.page_size {
        p = p.with_page_size(n);
    }
    map_inquire_result(p.prompt())
}

struct LongtextCfg {
    text: String,
    predefined: Option<String>,
    help: Option<String>,
    extension: Option<String>,
    editor: Option<String>,
}

fn run_longtext(cfg: &LongtextCfg) -> Result<Option<String>, PromptError> {
    let mut p = Editor::new(&cfg.text);
    if let Some(v) = &cfg.predefined {
        p = p.with_predefined_text(v);
    }
    if let Some(h) = &cfg.help {
        p = p.with_help_message(h);
    }
    if let Some(e) = &cfg.extension {
        p = p.with_file_extension(e);
    }
    if let Some(cmd) = &cfg.editor {
        p = p.with_editor_command(std::ffi::OsStr::new(cmd));
    }
    map_inquire_result(p.prompt())
}

struct SelectCfg {
    text: String,
    options: Vec<String>,
    help: Option<String>,
    page_size: Option<usize>,
    vim_mode: Option<bool>,
    filter: bool,
    // single mode
    starting_cursor: Option<usize>,
    // multiple mode
    default_indices: Vec<usize>,
    all_selected: bool,
    min_selected: Option<usize>,
    max_selected: Option<usize>,
}

fn run_select_single(cfg: &SelectCfg) -> Result<Option<String>, PromptError> {
    let mut p = Select::new(&cfg.text, cfg.options.clone());
    if let Some(idx) = cfg.starting_cursor {
        p = p.with_starting_cursor(idx);
    }
    if let Some(h) = &cfg.help {
        p = p.with_help_message(h);
    }
    if let Some(n) = cfg.page_size {
        p = p.with_page_size(n);
    }
    if let Some(v) = cfg.vim_mode {
        p = p.with_vim_mode(v);
    }
    if !cfg.filter {
        p = p.without_filtering();
    }
    map_inquire_result(p.prompt())
}

fn run_select_multiple(cfg: &SelectCfg) -> Result<Option<Vec<String>>, PromptError> {
    let mut p = MultiSelect::new(&cfg.text, cfg.options.clone());
    if !cfg.default_indices.is_empty() {
        p = p.with_default(&cfg.default_indices);
    }
    if cfg.all_selected {
        p = p.with_all_selected_by_default();
    }
    if let Some(h) = &cfg.help {
        p = p.with_help_message(h);
    }
    if let Some(n) = cfg.page_size {
        p = p.with_page_size(n);
    }
    if let Some(v) = cfg.vim_mode {
        p = p.with_vim_mode(v);
    }
    if !cfg.filter {
        p = p.without_filtering();
    }
    if cfg.min_selected.is_some() || cfg.max_selected.is_some() {
        let (min, max) = (cfg.min_selected, cfg.max_selected);
        let msg = bounds_message("number of selected options", &min, &max);
        p = p.with_validator(move |sel: &[ListOption<&String>]| {
            let n = sel.len();
            let ok = min.is_none_or(|m| n >= m) && max.is_none_or(|m| n <= m);
            if ok {
                Ok(Validation::Valid)
            } else {
                Ok(Validation::Invalid(msg.clone().into()))
            }
        });
    }
    map_inquire_result(p.prompt())
}

struct PasswordCfg {
    text: String,
    help: Option<String>,
    confirm: bool,
    display: PasswordDisplayMode,
    toggle: bool,
    min_len: Option<usize>,
}

fn run_password(cfg: &PasswordCfg) -> Result<Option<String>, PromptError> {
    let mut p = Password::new(&cfg.text).with_display_mode(cfg.display);
    if !cfg.confirm {
        p = p.without_confirmation();
    }
    if cfg.toggle {
        p = p.with_display_toggle_enabled();
    }
    if let Some(h) = &cfg.help {
        p = p.with_help_message(h);
    }
    if let Some(min) = cfg.min_len {
        let msg = bounds_message("length", &Some(min), &None);
        p = p.with_validator(move |s: &str| {
            if s.chars().count() >= min {
                Ok(Validation::Valid)
            } else {
                Ok(Validation::Invalid(msg.clone().into()))
            }
        });
    }
    map_inquire_result(p.prompt())
}

struct NumberCfg<T> {
    text: String,
    default: Option<T>,
    help: Option<String>,
    placeholder: Option<String>,
    min: Option<T>,
    max: Option<T>,
    parse_error: &'static str,
}

fn run_number<T>(cfg: &NumberCfg<T>) -> Result<Option<T>, PromptError>
where
    T: Clone + Copy + PartialOrd + fmt::Display + std::str::FromStr + Send + Sync + 'static,
{
    let mut p = CustomType::<T>::new(&cfg.text).with_error_message(cfg.parse_error);
    if let Some(d) = cfg.default {
        p = p.with_default(d);
    }
    if let Some(h) = &cfg.help {
        p = p.with_help_message(h);
    }
    if let Some(ph) = &cfg.placeholder {
        p = p.with_placeholder(ph);
    }
    if cfg.min.is_some() || cfg.max.is_some() {
        let (min, max) = (cfg.min, cfg.max);
        let msg = bounds_message("value", &min, &max);
        p = p.with_validator(move |v: &T| {
            let ok = min.is_none_or(|m| *v >= m) && max.is_none_or(|m| *v <= m);
            if ok {
                Ok(Validation::Valid)
            } else {
                Ok(Validation::Invalid(msg.clone().into()))
            }
        });
    }
    map_inquire_result(p.prompt())
}

struct DateCfg {
    text: String,
    default: Option<NaiveDate>,
    help: Option<String>,
    min: Option<NaiveDate>,
    max: Option<NaiveDate>,
    week_start: Option<chrono::Weekday>,
}

fn run_date(cfg: &DateCfg) -> Result<Option<NaiveDate>, PromptError> {
    let mut p = DateSelect::new(&cfg.text)
        // Show the answer as ISO too, not inquire's "Month Day, Year".
        .with_formatter(&|d| d.format(DATE_FMT).to_string());
    if let Some(d) = cfg.default {
        p = p.with_default(d);
    }
    if let Some(h) = &cfg.help {
        p = p.with_help_message(h);
    }
    if let Some(d) = cfg.min {
        p = p.with_min_date(d);
    }
    if let Some(d) = cfg.max {
        p = p.with_max_date(d);
    }
    if let Some(w) = cfg.week_start {
        p = p.with_week_start(w);
    }
    map_inquire_result(p.prompt())
}

/// Register the prompt functions on the `tui` table. Each binding validates
/// its arguments into the matching `*Cfg` struct above, then drives the
/// blocking worker through [`run_prompt`].
pub(super) fn install(lua: &Lua, tui: &LuaTable) -> LuaResult<()> {
    tui.raw_set(
        "confirm",
        lua.create_async_function(
            |_, (text, default, opts): (LuaValue, LuaValue, Option<LuaTable>)| async move {
                const F: &str = "tui.confirm";
                let opts = Opts::parse(F, opts, &["help", "placeholder"])?;
                let cfg = ConfirmCfg {
                    text: text_arg(F, text)?,
                    default: match default {
                        LuaValue::Nil => None,
                        LuaValue::Boolean(b) => Some(b),
                        other => {
                            return Err(ext_err!(
                                "{F}: default must be a boolean (got {})",
                                other.type_name()
                            ))
                        }
                    },
                    help: opts.string("help")?,
                    placeholder: opts.string("placeholder")?,
                };
                run_prompt(F, move || run_confirm(&cfg)).await
            },
        )?,
    )?;

    tui.raw_set(
        "promptText",
        lua.create_async_function(
            |_, (text, default, opts): (LuaValue, LuaValue, Option<LuaTable>)| async move {
                const F: &str = "tui.promptText";
                let opts = Opts::parse(
                    F,
                    opts,
                    &["help", "placeholder", "default", "minLen", "maxLen", "suggestions", "pageSize"],
                )?;
                let cfg = TextCfg {
                    text: text_arg(F, text)?,
                    initial: default_string(F, default)?,
                    default: opts.string("default")?,
                    help: opts.string("help")?,
                    placeholder: opts.string("placeholder")?,
                    min_len: opts.count("minLen")?,
                    max_len: opts.count("maxLen")?,
                    suggestions: opts.string_array("suggestions")?,
                    page_size: opts.count("pageSize")?,
                };
                check_bounds(F, &cfg.min_len, &cfg.max_len)?;
                run_prompt(F, move || run_text(&cfg)).await
            },
        )?,
    )?;

    tui.raw_set(
        "promptLongText",
        lua.create_async_function(
            |_, (text, default, opts): (LuaValue, LuaValue, Option<LuaTable>)| async move {
                const F: &str = "tui.promptLongText";
                let opts = Opts::parse(F, opts, &["help", "extension", "editor"])?;
                let cfg = LongtextCfg {
                    text: text_arg(F, text)?,
                    predefined: default_string(F, default)?,
                    help: opts.string("help")?,
                    extension: opts.string("extension")?.map(|e| normalize_extension(&e)),
                    editor: opts.string("editor")?,
                };
                run_prompt(F, move || run_longtext(&cfg)).await
            },
        )?,
    )?;

    tui.raw_set(
        "promptSelect",
        lua.create_async_function(
            |lua, (text, default, opts): (LuaValue, LuaValue, Option<LuaTable>)| async move {
                const F: &str = "tui.promptSelect";
                if opts.is_none() {
                    return Err(ext_err!("{F}: opts table with 'options' is required"));
                }
                let opts = Opts::parse(
                    F,
                    opts,
                    &[
                        "options", "multiple", "help", "pageSize", "vimMode", "filter",
                        "minSelected", "maxSelected", "allSelected",
                    ],
                )?;
                let options = opts
                    .string_array("options")?
                    .ok_or_else(|| ext_err!("{F}: opts table with 'options' is required"))?;
                if options.is_empty() {
                    return Err(ext_err!("{F}: options must not be empty"));
                }
                let multiple = opts.boolean("multiple")?.unwrap_or(false);

                let mut cfg = SelectCfg {
                    text: text_arg(F, text)?,
                    help: opts.string("help")?,
                    page_size: opts.count("pageSize")?,
                    vim_mode: opts.boolean("vimMode")?,
                    filter: opts.boolean("filter")?.unwrap_or(true),
                    starting_cursor: None,
                    default_indices: Vec::new(),
                    all_selected: opts.boolean("allSelected")?.unwrap_or(false),
                    min_selected: opts.count("minSelected")?,
                    max_selected: opts.count("maxSelected")?,
                    options,
                };
                check_bounds(F, &cfg.min_selected, &cfg.max_selected)?;
                if !multiple {
                    for key in ["minSelected", "maxSelected", "allSelected"] {
                        if !opts.raw(key)?.is_nil() {
                            return Err(ext_err!("{F}: option '{key}' requires multiple = true"));
                        }
                    }
                }

                // The default is matched against the options *by value*; a
                // stale default is a script bug, so it errors rather than
                // being silently ignored.
                match (multiple, default) {
                    (_, LuaValue::Nil) => {}
                    (false, LuaValue::String(s)) => {
                        let s = s
                            .to_str()
                            .map_err(|_| ext_err!("{F}: default must be valid UTF-8"))?;
                        cfg.starting_cursor = Some(find_option_index(F, &cfg.options, &s)?);
                    }
                    (false, other) => {
                        return Err(ext_err!(
                            "{F}: default must be a string (got {})",
                            other.type_name()
                        ))
                    }
                    (true, LuaValue::String(s)) => {
                        let s = s
                            .to_str()
                            .map_err(|_| ext_err!("{F}: default must be valid UTF-8"))?;
                        cfg.default_indices = vec![find_option_index(F, &cfg.options, &s)?];
                    }
                    (true, LuaValue::Table(t)) => {
                        for i in 1..=t.raw_len() {
                            match t.raw_get::<LuaValue>(i)? {
                                LuaValue::String(s) => {
                                    let s = s.to_str().map_err(|_| {
                                        ext_err!("{F}: default[{i}] must be valid UTF-8")
                                    })?;
                                    cfg.default_indices
                                        .push(find_option_index(F, &cfg.options, &s)?);
                                }
                                other => {
                                    return Err(ext_err!(
                                        "{F}: default[{i}] must be a string (got {})",
                                        other.type_name()
                                    ))
                                }
                            }
                        }
                    }
                    (true, other) => {
                        return Err(ext_err!(
                            "{F}: default must be a string or an array of strings (got {})",
                            other.type_name()
                        ))
                    }
                }

                if multiple {
                    let chosen = run_prompt(F, move || run_select_multiple(&cfg)).await?;
                    match chosen {
                        Some(items) => Ok(LuaValue::Table(lua.create_sequence_from(items)?)),
                        None => Ok(LuaValue::Nil),
                    }
                } else {
                    let chosen = run_prompt(F, move || run_select_single(&cfg)).await?;
                    match chosen {
                        Some(s) => Ok(LuaValue::String(lua.create_string(&s)?)),
                        None => Ok(LuaValue::Nil),
                    }
                }
            },
        )?,
    )?;

    tui.raw_set(
        "promptSecret",
        lua.create_async_function(
            |_, (text, opts): (LuaValue, Option<LuaTable>)| async move {
                const F: &str = "tui.promptSecret";
                let opts = Opts::parse(F, opts, &["help", "confirm", "display", "toggle", "minLen"])?;
                let cfg = PasswordCfg {
                    text: text_arg(F, text)?,
                    help: opts.string("help")?,
                    confirm: opts.boolean("confirm")?.unwrap_or(false),
                    display: match opts.string("display")?.as_deref() {
                        None | Some("masked") => PasswordDisplayMode::Masked,
                        Some("hidden") => PasswordDisplayMode::Hidden,
                        Some("full") => PasswordDisplayMode::Full,
                        Some(other) => {
                            return Err(ext_err!(
                                "{F}: option 'display' must be one of 'masked', 'hidden', 'full' (got '{other}')"
                            ))
                        }
                    },
                    toggle: opts.boolean("toggle")?.unwrap_or(false),
                    min_len: opts.count("minLen")?,
                };
                run_prompt(F, move || run_password(&cfg)).await
            },
        )?,
    )?;

    tui.raw_set(
        "promptNumber",
        lua.create_async_function(
            |_, (text, default, opts): (LuaValue, LuaValue, Option<LuaTable>)| async move {
                const F: &str = "tui.promptNumber";
                let opts = Opts::parse(F, opts, &["help", "placeholder", "min", "max"])?;
                let cfg = NumberCfg::<f64> {
                    text: text_arg(F, text)?,
                    default: match &default {
                        LuaValue::Nil => None,
                        LuaValue::Integer(i) => Some(*i as f64),
                        LuaValue::Number(n) => Some(*n),
                        other => {
                            return Err(ext_err!(
                                "{F}: default must be a number (got {})",
                                other.type_name()
                            ))
                        }
                    },
                    help: opts.string("help")?,
                    placeholder: opts.string("placeholder")?,
                    min: opts.number("min")?,
                    max: opts.number("max")?,
                    parse_error: "please enter a valid number",
                };
                check_bounds(F, &cfg.min, &cfg.max)?;
                run_prompt(F, move || run_number(&cfg)).await
            },
        )?,
    )?;

    tui.raw_set(
        "promptInt",
        lua.create_async_function(
            |_, (text, default, opts): (LuaValue, LuaValue, Option<LuaTable>)| async move {
                const F: &str = "tui.promptInt";
                let opts = Opts::parse(F, opts, &["help", "placeholder", "min", "max"])?;
                let cfg = NumberCfg::<i64> {
                    text: text_arg(F, text)?,
                    default: match int_of(&default) {
                        _ if default.is_nil() => None,
                        Some(i) => Some(i),
                        None => {
                            return Err(ext_err!(
                                "{F}: default must be an integer (got {})",
                                lua_value_brief(&default)
                            ))
                        }
                    },
                    help: opts.string("help")?,
                    placeholder: opts.string("placeholder")?,
                    min: opts.integer("min")?,
                    max: opts.integer("max")?,
                    parse_error: "please enter a whole number",
                };
                check_bounds(F, &cfg.min, &cfg.max)?;
                run_prompt(F, move || run_number(&cfg)).await
            },
        )?,
    )?;

    tui.raw_set(
        "promptDate",
        lua.create_async_function(
            |_, (text, default, opts): (LuaValue, LuaValue, Option<LuaTable>)| async move {
                const F: &str = "tui.promptDate";
                let opts = Opts::parse(F, opts, &["help", "min", "max", "weekStart"])?;
                let cfg = DateCfg {
                    text: text_arg(F, text)?,
                    default: match default_string(F, default)? {
                        None => None,
                        Some(s) => Some(parse_date(F, "default", &s)?),
                    },
                    help: opts.string("help")?,
                    min: opts.date("min")?,
                    max: opts.date("max")?,
                    week_start: match opts.string("weekStart")? {
                        None => None,
                        Some(s) => Some(s.parse::<chrono::Weekday>().map_err(|_| {
                            ext_err!("{F}: option 'weekStart' must be a weekday name like 'monday' (got '{s}')")
                        })?),
                    },
                };
                check_bounds(F, &cfg.min, &cfg.max)?;
                let picked = run_prompt(F, move || run_date(&cfg)).await?;
                Ok(picked.map(|d| d.format(DATE_FMT).to_string()))
            },
        )?,
    )?;

    Ok(())
}

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

    #[test]
    fn find_option_index_matches_by_value() {
        let opts = vec!["red".to_string(), "green".to_string()];
        assert_eq!(find_option_index("tui.promptSelect", &opts, "green").unwrap(), 1);
        let err = find_option_index("tui.promptSelect", &opts, "blue").unwrap_err();
        assert!(
            err.to_string()
                .contains("tui.promptSelect: default 'blue' is not one of the options"),
            "got: {err}"
        );
    }

    #[test]
    fn normalize_extension_adds_dot() {
        assert_eq!(normalize_extension("md"), ".md");
        assert_eq!(normalize_extension(".md"), ".md");
    }

    #[test]
    fn static_suggester_filters_case_insensitively() {
        let mut s = StaticSuggester(vec!["Apple".into(), "banana".into(), "Cherry".into()]);
        assert_eq!(s.get_suggestions("an").unwrap(), vec!["banana".to_string()]);
        assert_eq!(
            s.get_suggestions("A").unwrap(),
            vec!["Apple".to_string(), "banana".to_string()]
        );
        assert_eq!(s.get_suggestions("").unwrap().len(), 3);
        assert_eq!(s.get_suggestions("xyz").unwrap(), Vec::<String>::new());
    }
}