//! The saved characters: pick one up where you left them, or delete them.

use ratatui::Frame;
use ratatui::crossterm::event::{KeyCode, KeyEvent};
use ratatui::layout::{Constraint, Flex, Layout};
use ratatui::style::{Color, Style, Stylize};
use ratatui::text::{Line, Span};
use ratatui::widgets::{Block, Padding, Paragraph};

use super::flight;
use super::forge::colour;
use super::keys::{self, ACCENT, DIM};
use super::{Scene, Transition};
use crate::app::Ctx;
use crate::save::{self, Slot};

/// Lines each save takes in the list, the gap after it included.
const ROWS_EACH: u16 = 3;

pub struct Saves {
    slots: Vec<Slot>,
    selected: usize,
    /// Asking whether to delete the selected save.
    deleting: bool,
    problem: Option<String>,
}

impl Saves {
    pub fn new(ctx: &Ctx) -> Saves {
        let slots = ctx.saves.as_deref().map(save::list).unwrap_or_default();
        // Whoever you're playing is first, being the most recently saved.
        Saves { slots, selected: 0, deleting: false, problem: None }
    }

    fn playing(&self, ctx: &Ctx, i: usize) -> bool {
        ctx.slot.as_ref() == Some(&self.slots[i].path)
    }

    fn load(&mut self, ctx: &mut Ctx) -> Transition {
        let Some(slot) = self.slots.get(self.selected) else { return Transition::None };
        if let Err(why) = &slot.summary {
            self.problem = Some(format!("That save can't be read: {why}"));
            return Transition::None;
        }
        if !self.playing(ctx, self.selected) {
            ctx.autosave();
            if let Err(why) = save::load(&slot.path, ctx) {
                self.problem = Some(format!("That save can't be read: {why}"));
                return Transition::None;
            }
        }
        Transition::Replace(flight::resume(ctx))
    }

    fn delete(&mut self, ctx: &mut Ctx) {
        let path = self.slots[self.selected].path.clone();
        if let Err(why) = save::delete(&path) {
            self.problem = Some(format!("Couldn't delete it: {why}"));
            return;
        }
        // Delete who you're playing and there's no one left to save.
        if ctx.slot.as_ref() == Some(&path) {
            ctx.slot = None;
        }
        self.slots.remove(self.selected);
        self.selected = self.selected.min(self.slots.len().saturating_sub(1));
    }
}

/// "just now", "5 minutes ago", "3 days ago".
fn ago(seconds: u64) -> String {
    let (n, unit) = match seconds {
        0..60 => return "just now".into(),
        60..3600 => (seconds / 60, "minute"),
        3600..86_400 => (seconds / 3600, "hour"),
        _ => (seconds / 86_400, "day"),
    };
    match n {
        1 if unit == "hour" => "an hour ago".into(),
        1 => format!("a {unit} ago"),
        _ => format!("{n} {unit}s ago"),
    }
}

impl Scene for Saves {
    fn key(&mut self, key: KeyEvent, ctx: &mut Ctx) -> Transition {
        self.problem = None;
        if self.deleting {
            self.deleting = false;
            if matches!(key.code, KeyCode::Char('y' | 'Y')) {
                self.delete(ctx);
            }
            return Transition::None;
        }
        let last = self.slots.len().saturating_sub(1);
        match key.code {
            KeyCode::Esc | KeyCode::Char('q') => return Transition::Pop,
            KeyCode::Up | KeyCode::Char('k') => self.selected = self.selected.saturating_sub(1),
            KeyCode::Down | KeyCode::Char('j') => self.selected = (self.selected + 1).min(last),
            KeyCode::Enter => return self.load(ctx),
            KeyCode::Char('d') | KeyCode::Delete if !self.slots.is_empty() => self.deleting = true,
            _ => {}
        }
        Transition::None
    }

    fn render(&self, frame: &mut Frame, ctx: &Ctx) {
        let [area] =
            Layout::horizontal([Constraint::Length(84)]).flex(Flex::Center).areas(frame.area());
        let block = Block::bordered()
            .border_style(Style::new().fg(DIM))
            .title(Line::from(" SAVED CHARACTERS ").fg(ACCENT).bold())
            .padding(Padding::uniform(1));
        let inner = block.inner(area);
        frame.render_widget(block, area);
        let [list, _, footer] =
            Layout::vertical([Constraint::Fill(1), Constraint::Length(1), Constraint::Length(2)])
                .areas(inner);

        let mut lines = Vec::new();
        if self.slots.is_empty() {
            lines.push(
                Line::from("No one's saved yet. Make a new character from the title.").fg(DIM),
            );
        }
        // Enough of the list to keep the selected save in view.
        let shown = usize::from((list.height / ROWS_EACH).max(1));
        let first = (self.selected + 1).saturating_sub(shown);
        let now = save::now();
        for (i, slot) in self.slots.iter().enumerate().skip(first).take(shown) {
            let chosen = i == self.selected;
            let marker = if chosen { Span::raw("› ").fg(ACCENT).bold() } else { Span::raw("  ") };
            match &slot.summary {
                Ok(s) => {
                    let c = &s.character;
                    let mut who = vec![
                        marker,
                        Span::raw(c.name.clone()).fg(colour(c.origin)).bold(),
                        Span::raw(format!(", {}, of {}", c.calling(), c.ship_name())),
                    ];
                    if self.playing(ctx, i) {
                        who.push(Span::raw("  playing").fg(ACCENT));
                    }
                    lines.push(Line::from(who));
                    let boarded = match s.record.boarded {
                        1 => "1 wreck boarded".to_string(),
                        n => format!("{n} wrecks boarded"),
                    };
                    lines.push(
                        Line::from(format!(
                            "    day {:.1} at {} · {} ¤ · {boarded} · saved {}",
                            s.day,
                            s.place,
                            s.scrip,
                            ago(now.saturating_sub(s.saved))
                        ))
                        .fg(DIM),
                    );
                }
                Err(why) => {
                    let file = slot.path.file_name().unwrap_or_default().to_string_lossy();
                    lines.push(Line::from(vec![marker, Span::raw(file.into_owned()).fg(DIM)]));
                    lines.push(Line::from(format!("    can't be read: {why}")).fg(Color::LightRed));
                }
            }
            lines.push(Line::default());
        }
        frame.render_widget(Paragraph::new(lines), list);

        let name = |i: usize| match &self.slots[i].summary {
            Ok(s) => s.character.name.clone(),
            Err(_) => "this save".into(),
        };
        let mut help = Vec::new();
        if self.deleting {
            let who = name(self.selected);
            help.push(Line::from(format!("Delete {who} for good?")).fg(Color::LightRed));
            help.push(keys::line(&[("y", "delete"), ("any other key", "keep them")]));
        } else {
            if let Some(problem) = &self.problem {
                help.push(Line::from(problem.as_str()).fg(Color::LightRed));
            } else if let Some(dir) = &ctx.saves {
                help.push(Line::from(format!("saved in {}", dir.display())).fg(DIM));
            }
            help.push(keys::line(&[
                ("↑↓", "choose"),
                ("enter", "play"),
                ("d", "delete"),
                ("esc", "back"),
            ]));
        }
        frame.render_widget(Paragraph::new(help), footer);
    }
}

#[cfg(test)]
mod tests {
    use ratatui::crossterm::event::KeyModifiers;

    use super::*;
    use crate::names::Culture;
    use crate::save::Character;
    use crate::term::KeyboardCaps;

    fn press(scene: &mut Saves, ctx: &mut Ctx, code: KeyCode) -> Transition {
        scene.key(KeyEvent::new(code, KeyModifiers::NONE), ctx)
    }

    /// A saves folder with two characters in it, and the game playing the
    /// second.
    fn two(dir: &std::path::Path) -> Ctx {
        let mut ctx = Ctx::new(1, KeyboardCaps { key_release: false });
        ctx.saves = Some(dir.to_path_buf());
        for (name, universe, scrip) in [("Ada Vell", 11, 300), ("Bram Oskel", 22, 5)] {
            let character =
                Character { name: name.into(), origin: Culture::Cant, ship: "Bolt".into() };
            ctx.begin(universe, character);
            ctx.slot = Some(save::new_slot(dir, &ctx.character, universe));
            ctx.hold.scrip = scrip;
            ctx.autosave();
            assert!(ctx.save_error.is_none());
        }
        ctx
    }

    #[test]
    fn loading_picks_up_where_they_left_off() {
        let dir = save::scratch("saves-load");
        let mut ctx = two(&dir);
        let mut saves = Saves::new(&ctx);
        assert_eq!(saves.slots.len(), 2);
        // Both were saved within the same second, so either may come first.
        let ada = saves
            .slots
            .iter()
            .position(|s| s.summary.as_ref().unwrap().character.name == "Ada Vell")
            .unwrap();
        ctx.hold.scrip = 6;
        saves.selected = ada;
        assert!(matches!(press(&mut saves, &mut ctx, KeyCode::Enter), Transition::Replace(_)));
        assert_eq!((ctx.character.name.as_str(), ctx.seed, ctx.hold.scrip), ("Ada Vell", 11, 300));

        // Bram was saved as they were left, scrip and all.
        let bram = save::new_slot(
            &dir,
            &Character { name: "Bram Oskel".into(), origin: Culture::Cant, ship: "Bolt".into() },
            22,
        );
        save::load(&bram, &mut ctx).unwrap();
        assert_eq!(ctx.hold.scrip, 6);
        let _ = std::fs::remove_dir_all(dir);
    }

    #[test]
    fn deleting_asks_first() {
        let dir = save::scratch("saves-delete");
        let mut ctx = two(&dir);
        let mut saves = Saves::new(&ctx);
        press(&mut saves, &mut ctx, KeyCode::Char('d'));
        press(&mut saves, &mut ctx, KeyCode::Char('n'));
        assert_eq!(saves.slots.len(), 2, "anything but yes keeps it");
        let playing = saves.playing(&ctx, 0);
        press(&mut saves, &mut ctx, KeyCode::Char('d'));
        press(&mut saves, &mut ctx, KeyCode::Char('y'));
        assert_eq!((saves.slots.len(), save::list(&dir).len()), (1, 1));
        assert_eq!(ctx.slot.is_none(), playing, "delete who you're playing and nothing's saved");
        let _ = std::fs::remove_dir_all(dir);
    }

    #[test]
    fn saved_times_read_naturally() {
        assert_eq!(ago(5), "just now");
        assert_eq!(ago(60), "a minute ago");
        assert_eq!(ago(3 * 3600 + 5), "3 hours ago");
        assert_eq!(ago(3600), "an hour ago");
        assert_eq!(ago(86_400 * 2), "2 days ago");
    }
}