//! Tracks the per-date daily challenge: a deterministic seed every player
//! sees on a given calendar day, plus completion bookkeeping.
//!
//! When the player wins a game whose seed matches today's daily seed and
//! today's date hasn't been completed yet, this plugin:
//!   - calls `PlayerProgress::record_daily_completion`
//!   - awards a fixed XP bonus (`DAILY_BONUS_XP`)
//!   - persists progress
//!   - emits `DailyChallengeCompletedEvent`
//!
//! Pressing **C** fires a `NewGameRequestEvent` with today's daily seed so
//! the player can start a fresh attempt.

use bevy::input::ButtonInput;
use bevy::prelude::*;
use chrono::{Local, NaiveDate};
use solitaire_data::{daily_seed_for, save_progress_to};

use crate::events::{GameWonEvent, NewGameRequestEvent};
use crate::game_plugin::GameMutation;
use crate::progress_plugin::{ProgressResource, ProgressStoragePath, ProgressUpdate};
use crate::resources::GameStateResource;

/// Bonus XP awarded for completing today's daily challenge.
pub const DAILY_BONUS_XP: u64 = 100;

/// The active daily challenge — date + RNG seed for that date's deal.
#[derive(Resource, Debug, Clone, Copy)]
pub struct DailyChallengeResource {
    pub date: NaiveDate,
    pub seed: u64,
}

impl DailyChallengeResource {
    pub fn for_today() -> Self {
        let date = Local::now().date_naive();
        Self {
            date,
            seed: daily_seed_for(date),
        }
    }
}

/// Fired when the player has just completed today's daily challenge.
#[derive(Event, Debug, Clone, Copy)]
pub struct DailyChallengeCompletedEvent {
    pub date: NaiveDate,
    pub streak: u32,
}

pub struct DailyChallengePlugin;

impl Plugin for DailyChallengePlugin {
    fn build(&self, app: &mut App) {
        app.insert_resource(DailyChallengeResource::for_today())
            .add_event::<DailyChallengeCompletedEvent>()
            .add_event::<GameWonEvent>()
            .add_event::<NewGameRequestEvent>()
            // record/award after the base ProgressUpdate so we don't fight
            // ProgressPlugin's add_xp on the same frame.
            .add_systems(Update, handle_daily_completion.after(ProgressUpdate))
            .add_systems(Update, handle_start_daily_request.before(GameMutation));
    }
}

fn handle_daily_completion(
    mut wins: EventReader<GameWonEvent>,
    daily: Res<DailyChallengeResource>,
    game: Res<GameStateResource>,
    mut progress: ResMut<ProgressResource>,
    path: Res<ProgressStoragePath>,
    mut completed: EventWriter<DailyChallengeCompletedEvent>,
) {
    for _ in wins.read() {
        if game.0.seed != daily.seed {
            continue;
        }
        if !progress.0.record_daily_completion(daily.date) {
            // Already counted today — no-op.
            continue;
        }
        progress.0.add_xp(DAILY_BONUS_XP);
        if let Some(target) = &path.0 {
            if let Err(e) = save_progress_to(target, &progress.0) {
                warn!("failed to save progress after daily completion: {e}");
            }
        }
        completed.send(DailyChallengeCompletedEvent {
            date: daily.date,
            streak: progress.0.daily_challenge_streak,
        });
    }
}

fn handle_start_daily_request(
    keys: Res<ButtonInput<KeyCode>>,
    daily: Res<DailyChallengeResource>,
    mut new_game: EventWriter<NewGameRequestEvent>,
) {
    if keys.just_pressed(KeyCode::KeyC) {
        new_game.send(NewGameRequestEvent {
            seed: Some(daily.seed),
            mode: None,
        });
    }
}

#[cfg(test)]
mod tests {
    use super::*;
    use crate::game_plugin::GamePlugin;
    use crate::progress_plugin::ProgressPlugin;
    use crate::table_plugin::TablePlugin;
    use solitaire_core::game_state::{DrawMode, GameState};

    fn headless_app() -> App {
        let mut app = App::new();
        app.add_plugins(MinimalPlugins)
            .add_plugins(GamePlugin)
            .add_plugins(TablePlugin)
            .add_plugins(ProgressPlugin::headless())
            .add_plugins(DailyChallengePlugin);
        app.init_resource::<ButtonInput<KeyCode>>();
        app.update();
        app
    }

    #[test]
    fn resource_uses_today() {
        let app = headless_app();
        let r = app.world().resource::<DailyChallengeResource>();
        assert_eq!(r.date, Local::now().date_naive());
        assert_eq!(r.seed, daily_seed_for(r.date));
    }

    #[test]
    fn winning_with_daily_seed_completes_and_fires_event() {
        let mut app = headless_app();
        let daily_seed = app.world().resource::<DailyChallengeResource>().seed;

        // Replace the GameState with one whose seed matches the daily seed.
        app.world_mut().resource_mut::<GameStateResource>().0 =
            GameState::new(daily_seed, DrawMode::DrawOne);

        app.world_mut().send_event(GameWonEvent {
            score: 500,
            time_seconds: 200,
        });
        app.update();

        let progress = &app.world().resource::<ProgressResource>().0;
        assert_eq!(progress.daily_challenge_streak, 1);
        // +100 from the daily bonus
        assert!(progress.total_xp >= DAILY_BONUS_XP);

        let events = app.world().resource::<Events<DailyChallengeCompletedEvent>>();
        let mut cursor = events.get_cursor();
        let fired: Vec<_> = cursor.read(events).copied().collect();
        assert_eq!(fired.len(), 1);
        assert_eq!(fired[0].streak, 1);
    }

    #[test]
    fn winning_with_unrelated_seed_does_not_complete_daily() {
        let mut app = headless_app();
        let daily_seed = app.world().resource::<DailyChallengeResource>().seed;
        // Use a deliberately different seed.
        app.world_mut().resource_mut::<GameStateResource>().0 =
            GameState::new(daily_seed.wrapping_add(7777), DrawMode::DrawOne);

        app.world_mut().send_event(GameWonEvent {
            score: 500,
            time_seconds: 200,
        });
        app.update();

        let progress = &app.world().resource::<ProgressResource>().0;
        assert_eq!(progress.daily_challenge_streak, 0);

        let events = app.world().resource::<Events<DailyChallengeCompletedEvent>>();
        let mut cursor = events.get_cursor();
        assert!(cursor.read(events).next().is_none());
    }

    #[test]
    fn second_win_same_day_is_idempotent() {
        let mut app = headless_app();
        let daily_seed = app.world().resource::<DailyChallengeResource>().seed;
        app.world_mut().resource_mut::<GameStateResource>().0 =
            GameState::new(daily_seed, DrawMode::DrawOne);

        app.world_mut().send_event(GameWonEvent {
            score: 500,
            time_seconds: 200,
        });
        app.update();
        // Re-send win.
        app.world_mut().send_event(GameWonEvent {
            score: 500,
            time_seconds: 200,
        });
        app.update();

        let progress = &app.world().resource::<ProgressResource>().0;
        assert_eq!(progress.daily_challenge_streak, 1, "streak does not double-count");
    }

    #[test]
    fn pressing_c_fires_new_game_with_daily_seed() {
        let mut app = headless_app();
        let daily_seed = app.world().resource::<DailyChallengeResource>().seed;

        app.world_mut()
            .resource_mut::<ButtonInput<KeyCode>>()
            .press(KeyCode::KeyC);
        app.update();

        let events = app.world().resource::<Events<NewGameRequestEvent>>();
        let mut cursor = events.get_cursor();
        let fired: Vec<_> = cursor.read(events).copied().collect();
        assert_eq!(fired.len(), 1);
        assert_eq!(fired[0].seed, Some(daily_seed));
    }
}