// Settings module (#627)
// Persistent settings via SQLite on the server side.
// Architecture: settings live on the SERVER in a SQLite database with per-player
// tables. The client sends ChangeSettings commands over IPC, same as any other
// player action. The client never touches the database directly.
//
// Scope: keybindings, audio volume, display preferences, accessibility options,
// AI-Enhanced Dialogue toggle (#646).

pub mod store;
pub mod types;

use bevy_app::prelude::*;
use bevy_ecs::prelude::*;
use std::sync::Mutex;

pub use store::SettingsStore;
pub use types::{SettingEntry, SettingValue, SettingsResponseWire};

/// Bevy resource wrapping the SQLite settings store.
///
/// Initialized at server startup with a path derived from the save directory.
/// v0.1: single player, player_id = "default".
/// Multiplayer-ready: per-player isolation via player_id column (D-010).
///
/// Uses Mutex because rusqlite::Connection is !Sync. The lock is held only
/// for the duration of each operation (sub-millisecond for SQLite).
#[derive(Resource)]
pub struct SettingsStoreResource {
    store: Mutex<SettingsStore>,
    /// Player ID for settings isolation. v0.1: always "default".
    player_id: String,
}

impl SettingsStoreResource {
    pub fn new(store: SettingsStore, player_id: String) -> Self {
        Self {
            store: Mutex::new(store),
            player_id,
        }
    }

    /// Get a single setting.
    pub fn get(&self, key: &str) -> Option<SettingValue> {
        let store = self.store.lock().expect("settings mutex poisoned");
        match store.get(&self.player_id, key) {
            Ok(val) => val,
            Err(e) => {
                tracing::error!("settings get({}) failed: {}", key, e);
                None
            }
        }
    }

    /// Set a single setting. Returns true on success.
    pub fn set(&self, key: &str, value: &SettingValue) -> bool {
        let store = self.store.lock().expect("settings mutex poisoned");
        match store.set(&self.player_id, key, value) {
            Ok(()) => {
                tracing::debug!("settings set: {} = {}", key, value);
                true
            }
            Err(e) => {
                tracing::error!("settings set({}) failed: {}", key, e);
                false
            }
        }
    }

    /// Delete a single setting. Returns true if it existed.
    pub fn delete(&self, key: &str) -> bool {
        let store = self.store.lock().expect("settings mutex poisoned");
        match store.delete(&self.player_id, key) {
            Ok(deleted) => deleted,
            Err(e) => {
                tracing::error!("settings delete({}) failed: {}", key, e);
                false
            }
        }
    }

    /// Get all settings as wire entries.
    pub fn get_all_entries(&self) -> Vec<SettingEntry> {
        let store = self.store.lock().expect("settings mutex poisoned");
        match store.get_all_entries(&self.player_id) {
            Ok(entries) => entries,
            Err(e) => {
                tracing::error!("settings get_all failed: {}", e);
                vec![]
            }
        }
    }
}

/// Buffer for pending settings commands received via IPC.
/// Drained by `process_settings_commands` each tick.
#[derive(Resource, Debug, Default)]
pub struct SettingsCommandBuffer {
    commands: Vec<SettingsCommand>,
}

impl SettingsCommandBuffer {
    pub fn push(&mut self, cmd: SettingsCommand) {
        self.commands.push(cmd);
    }

    pub fn drain(&mut self) -> Vec<SettingsCommand> {
        std::mem::take(&mut self.commands)
    }
}

/// Settings command variants queued from PlayerAction.
#[derive(Debug, Clone)]
pub enum SettingsCommand {
    /// Change a single setting.
    Change { key: String, value: SettingValue },
    /// Request a full settings dump.
    RequestAll,
    /// Delete a single setting (restore to default).
    Delete { key: String },
}

/// Process settings commands from the IPC buffer.
/// Reads SettingsCommandBuffer, writes to SettingsStoreResource,
/// and stages a response in SnapshotBuffer.pending_settings_response.
pub fn process_settings_commands(
    settings_store: Option<Res<SettingsStoreResource>>,
    mut cmd_buffer: ResMut<SettingsCommandBuffer>,
    mut snapshot_buffer: ResMut<crate::bridge::types::SnapshotBuffer>,
) {
    let commands = cmd_buffer.drain();
    if commands.is_empty() {
        return;
    }

    let Some(store) = settings_store else {
        tracing::warn!("settings commands received but SettingsStoreResource not registered");
        return;
    };

    // Process all commands, last response wins (same tick batching).
    // If multiple settings commands arrive in one tick, only the final response
    // reaches the client. This is acceptable: the client sends one action per tick
    // in normal use, and batch changes via RequestAll after bulk updates.
    for cmd in commands {
        match cmd {
            SettingsCommand::Change { ref key, ref value } => {
                if store.set(key, value) {
                    snapshot_buffer.pending_settings_response = Some(SettingsResponseWire {
                        success: true,
                        kind: "ack".into(),
                        settings: vec![SettingEntry {
                            key: key.clone(),
                            value: value.clone(),
                        }],
                        error: None,
                    });
                } else {
                    snapshot_buffer.pending_settings_response = Some(SettingsResponseWire {
                        success: false,
                        kind: "ack".into(),
                        settings: vec![],
                        error: Some(format!("failed to set setting: {}", key)),
                    });
                }
            }
            SettingsCommand::RequestAll => {
                let entries = store.get_all_entries();
                snapshot_buffer.pending_settings_response = Some(SettingsResponseWire {
                    success: true,
                    kind: "full".into(),
                    settings: entries,
                    error: None,
                });
            }
            SettingsCommand::Delete { ref key } => {
                // Idempotent: deleting a non-existent key is a silent no-op.
                let _deleted = store.delete(key);
                snapshot_buffer.pending_settings_response = Some(SettingsResponseWire {
                    success: true,
                    kind: "ack".into(),
                    settings: vec![],
                    error: None,
                });
            }
        }
    }
}

/// Settings plugin. Registers resources and the processing system.
pub struct SettingsPlugin;

impl Plugin for SettingsPlugin {
    fn build(&self, app: &mut App) {
        app.init_resource::<SettingsCommandBuffer>().add_systems(
            Update,
            process_settings_commands
                .after(crate::simulation::input::process_player_input)
                .before(crate::perception::observer::compute_observer_snapshot),
        );
        tracing::debug!("SettingsPlugin initialized");
    }
}