//! The command line, opened with `:` like in vim. Handy for things that
//! need a few words: `:pause 17:30`, `:export csv lastmonth`,
//! `:set time_format=12h`.

use jiff::Timestamp;
use jiff::civil::Date;
use ratatui::Frame;
use ratatui::crossterm::event::KeyEvent;
use ratatui::layout::Rect;
use ratatui::style::Style;
use ratatui::text::{Line, Span};
use ratatui::widgets::{Clear, Paragraph};

use super::export_dialog::named_ranges;
use crate::action::Action;
use crate::export::ExportFormat;
use crate::export::timesheet::CopyPreset;
use crate::settings::{Choice, FIELDS, Kind};
use crate::time::DateRange;
use crate::time::format::parse_time;
use crate::time::resolve::latest_until;
use crate::ui::keymap::{Binding, Command};
use crate::ui::widgets::text_input::{InputEvent, TextInput};
use crate::ui::{Component, Context, Tab};

/// Every command, for the help screen.
pub const COMMANDS: &[(&str, &str)] = &[
    (":start [time]", "start now, or at an earlier time"),
    (":pause [time]", "pause now, or at an earlier time"),
    (":end [time]", "end the work day, now or at an earlier time"),
    (":copy [format] [week]", "copy; formats: clock decimal segments inout custom"),
    (":export [format] [dates]", "csv json md; week lastweek month lastmonth 30d year all"),
    ("", "   dates can also be 2026-09 or 2026-09-01..2026-09-15"),
    (":set name=value", "change a setting (name? shows it, name& resets it)"),
    (":set name  :set noname", "turn an on/off setting on or off (name! flips it)"),
    (":undo  :redo", "undo / redo"),
    (":snooze", "snooze the break reminder"),
    (":break", "take a pomodoro break / back from it"),
    (":tracker :days :insights :settings", "go to a screen"),
    (":help", "all keys"),
    (":q", "quit"),
];

#[derive(Default)]
pub struct CommandLine {
    input: TextInput,
    error: Option<String>,
}

impl CommandLine {
    pub fn new() -> CommandLine {
        CommandLine::default()
    }
}

impl Component for CommandLine {
    fn keys(&self) -> &'static [&'static [Binding]] {
        &[]
    }

    /// Drawn over the status line at the bottom of the window.
    fn render(&mut self, frame: &mut Frame, area: Rect, ctx: &Context) {
        let bottom = Rect { y: area.bottom().saturating_sub(1), height: 1, ..area };
        frame.render_widget(Clear, bottom);
        let mut line = self.input.line(true, Style::new());
        line.spans.insert(0, Span::styled(":", ctx.theme.title()));
        frame.render_widget(Paragraph::new(line), bottom);

        if let Some(error) = &self.error {
            let above = Rect { y: bottom.y.saturating_sub(1), ..bottom };
            frame.render_widget(Clear, above);
            frame.render_widget(
                Paragraph::new(Line::styled(error.clone(), Style::new().fg(ctx.theme.error))),
                above,
            );
        }
    }

    fn command(&mut self, command: Command, _count: Option<usize>, _ctx: &Context) -> Option<Action> {
        (command == Command::Close).then_some(Action::ClosePopup)
    }

    fn inserting(&self) -> bool {
        true
    }

    fn insert_key(&mut self, key: KeyEvent, ctx: &Context) -> Option<Action> {
        self.error = None;
        match self.input.insert_key(key) {
            InputEvent::Submit => match parse(self.input.text(), ctx) {
                Ok(action) => Some(action),
                Err(error) => {
                    self.error = Some(error);
                    None
                }
            },
            InputEvent::Exit => Some(Action::ClosePopup),
            _ => None,
        }
    }
}

/// Turns a command line into an action.
pub fn parse(text: &str, ctx: &Context) -> Result<Action, String> {
    let mut words = text.split_whitespace();
    let Some(name) = words.next() else { return Ok(Action::ClosePopup) };
    let rest: Vec<&str> = words.collect();

    // An optional time after the command, as the latest moment it happened.
    let moment = || -> Result<Option<Timestamp>, String> {
        match rest.first() {
            None => Ok(None),
            Some(text) => {
                let time = parse_time(text).map_err(|error| error.to_string())?;
                Ok(Some(latest_until(time, ctx.now).timestamp()))
            }
        }
    };

    match name {
        "q" | "q!" | "quit" | "wq" | "x" | "qa" => Ok(Action::Quit),
        "w" => Ok(Action::Notify("skyshift saves every change right away".into())),
        "start" => Ok(moment()?.map_or(Action::Start, Action::StartAt)),
        "pause" => Ok(moment()?.map_or(Action::Pause, Action::PauseAt)),
        "end" => Ok(moment()?.map_or(Action::EndDay, Action::EndDayAt)),
        "undo" | "u" => Ok(Action::Undo),
        "redo" => Ok(Action::Redo),
        "snooze" => Ok(Action::Snooze),
        "break" => Ok(Action::TakeBreak),
        "tracker" => Ok(Action::GoTo(Tab::Tracker)),
        "days" => Ok(Action::GoTo(Tab::Days)),
        "insights" => Ok(Action::GoTo(Tab::Insights)),
        "settings" => Ok(Action::GoTo(Tab::Settings)),
        "help" | "h" => Ok(Action::ShowHelp),
        "copy" | "y" => copy(&rest, ctx),
        "export" => export(&rest, ctx),
        "set" | "se" => set(&rest.join(" "), ctx),
        other => Err(format!("unknown command :{other} (:help lists them)")),
    }
}

fn copy(words: &[&str], ctx: &Context) -> Result<Action, String> {
    let mut preset = ctx.settings.copy_preset;
    let mut week = false;
    for word in words {
        match *word {
            "week" => week = true,
            "day" => week = false,
            "clock" | "hm" | "total" => preset = CopyPreset::TotalClock,
            "decimal" => preset = CopyPreset::TotalDecimal,
            "segments" => preset = CopyPreset::Segments,
            "inout" => preset = CopyPreset::InOutBreak,
            "custom" | "template" => preset = CopyPreset::Custom,
            other => {
                preset = CopyPreset::from_name(other).ok_or(format!("unknown copy format \"{other}\""))?
            }
        }
    }
    let day = ctx.current_day();
    let days = if week { ctx.week_days(day) } else { vec![day] };
    Ok(Action::Copy { days, preset })
}

fn export(words: &[&str], ctx: &Context) -> Result<Action, String> {
    let mut format = ctx.settings.export_format;
    let today = ctx.now.date();
    let named = named_ranges(today, ctx.settings.week_start, ctx.days);
    let mut range = named[0].2;
    for word in words {
        if let Some(found) = ExportFormat::from_name(word) {
            format = found;
        } else if *word == "md" {
            format = ExportFormat::Markdown;
        } else if let Some((_, _, found)) = named.iter().find(|(_, name, _)| name == word) {
            range = *found;
        } else {
            range = parse_dates(word)?;
        }
    }
    Ok(Action::Export { format, range })
}

/// "2026-09" (a month), "2026-09-24" (a day) or "2026-09-01..2026-09-15".
fn parse_dates(text: &str) -> Result<DateRange, String> {
    let error =
        || format!("\"{text}\" isn't a format or dates (try week, month, 2026-09 or 2026-09-01..2026-09-15)");
    let date = |text: &str| text.parse::<Date>().map_err(|_| error());
    if let Some((first, last)) = text.split_once("..") {
        return Ok(DateRange::new(date(first)?, date(last)?));
    }
    if text.len() == 7 {
        return Ok(DateRange::month_of(date(&format!("{text}-01"))?));
    }
    let day = date(text)?;
    Ok(DateRange::new(day, day))
}

/// `name=value`, `name value`, `name?` (show), `name&` (reset), and for
/// on/off settings `name`, `noname` and `name!` (flip), like vim.
fn set(text: &str, ctx: &Context) -> Result<Action, String> {
    let text = text.trim();
    if text.is_empty() {
        return Err("usage: :set name=value (the names are in config.toml)".into());
    }
    let (name, value) = match text.split_once(['=', ' ']) {
        Some((name, value)) => (name.trim(), Some(value.trim())),
        None => (text, None),
    };
    let find = |name: &str| FIELDS.iter().find(|field| field.key == name);

    if let Some(name) = name.strip_suffix('?') {
        let field = find(name).ok_or(format!("no setting named {name}"))?;
        return Ok(Action::Notify(format!("{} = {}", field.key, (field.get)(ctx.settings))));
    }
    if let Some(name) = name.strip_suffix('&') {
        let field = find(name).ok_or(format!("no setting named {name}"))?;
        return Ok(Action::ResetSetting { key: field.key });
    }
    if let Some(value) = value {
        let field = find(name).ok_or(format!("no setting named {name}"))?;
        return Ok(Action::SetSetting { key: field.key, value: value.to_string() });
    }

    // On/off settings: `mouse`, `nomouse`, `mouse!`.
    let (name, value) = if let Some(name) = name.strip_suffix('!') {
        let field = find(name).ok_or(format!("no setting named {name}"))?;
        let on = (field.get)(ctx.settings) == "true";
        (name, (!on).to_string())
    } else if let Some(name) = name.strip_prefix("no").filter(|name| find(name).is_some()) {
        (name, "false".to_string())
    } else {
        (name, "true".to_string())
    };
    let field = find(name).ok_or(format!("no setting named {name}"))?;
    if !matches!(field.kind, Kind::Toggle) {
        return Err(format!("{name} isn't an on/off setting: use :set {name}=value"));
    }
    Ok(Action::SetSetting { key: field.key, value })
}